# Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion: a three-dimensional study

Anaïs Martin, Mathilde Oyallon, Jean Philippe Perrin, Thomas Durand, Laurent Deumier, Pierre Corre, Stéphane Renaudin, Hélios Bertin

<figure><img src="image_1.png" /></figure>

## To cite this version:

Anaïs Martin, Mathilde Oyallon, Jean Philippe Perrin, Thomas Durand, Laurent Deumier, et al. "Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion: a three-dimensional study." Journal of Stomatology, Oral and Maxillofacial Surgery, 2023, 124 (1), pp.101331. 10.1016/j.jormas.2022.11.007. hal-04600597

HAL Id: hal-04600597

https://hal.science/hal-04600597

Submitted on 4 Jun 2024

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## TITLE

Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion:

a three-dimensional study

## AUTHORS NAME AND AFFILIATIONS

Anais Martin<sup>a</sup> (D.D.S.)
anais.martin@chu-nantes.fr

Mathilde Oyallon<sup>a</sup> (D.D.S.)
mathilde.oyallon@chu-nantes.fr

Jean Philippe Perrin<sup>b</sup> (M.D.)
jeanphilippe.perrin@chu-nantes.fr

Thomas Durand<sup>b</sup> (D.D.S.)
thomas.durand@chu-nantes.fr

Laurent Deumier<sup>b</sup> (D.D.S.)
laurent.deumier@chu-nantes.fr

Pierre Corre<sup>b,c</sup> (M.D., Ph.D.)
pierre.corre@chu-nantes.fr

Stéphane Renaudin<sup>a</sup> (D.D.S., Ph.D.)
stephane.renaudin@univ-nantes.fr

Hélios Bertin<sup>b,d*</sup> (M.D., Ph.D.)
helios.bertin@chu-nantes.fr

Tel: +33 (0)2 40 08 36 79

Fax: +33 (0)2 40 08 36 68

<footnote>* Corresponding author</footnote>
## TITLE

Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion:

a three-dimensional study

## AUTHORS NAME AND AFFILIATIONS

Anais Martin<sup>a</sup> (D.D.S.)
anais.martin@chu-nantes.fr

Mathilde Oyallon<sup>a</sup> (D.D.S.)
mathilde.oyallon@chu-nantes.fr

Jean Philippe Perrin<sup>b</sup> (M.D.)
jeanphilippe.perrin@chu-nantes.fr

Thomas Durand<sup>b</sup> (D.D.S.)
thomas.durand@chu-nantes.fr

Laurent Deumier<sup>b</sup> (D.D.S.)
laurent.deumier@chu-nantes.fr

Pierre Corre<sup>b,c</sup> (M.D., Ph.D.)
pierre.corre@chu-nantes.fr

Stéphane Renaudin<sup>a</sup> (D.D.S., Ph.D.)
stephane.renaudin@univ-nantes.fr

Hélios Bertin<sup>b,d*</sup> (M.D., Ph.D.)
helios.bertin@chu-nantes.fr

Tel: +33 (0)2 40 08 36 79

Fax: +33 (0)2 40 08 36 68

<footnote>* Corresponding author</footnote>
a Département d'orthopédie dento-faciale, Faculté dentaire de Nantes, CHU de Nantes, 1 place Alexis Ricordeau, 44093 Nantes, France

b Nantes Université, CHU Nantes, Service de chirurgie maxillo-faciale et stomatologie, F-44000 Nantes, France

c Nantes Université, Oniris, UnivAngers, CHU Nantes, INSERM, Regenerative Medicine and Skeleton, RMeS, UMR 1229, F-44000 Nantes, France

d Nantes Université, UnivAngers, CHU Nantes, INSERM, CNRS, CRCI2NA, F-44000 Nantes, France
a Département d'orthopédie dento-faciale, Faculté dentaire de Nantes, CHU de Nantes, 1 place Alexis Ricordeau, 44093 Nantes, France

b Nantes Université, CHU Nantes, Service de chirurgie maxillo-faciale et stomatologie, F-44000 Nantes, France

c Nantes Université, Oniris, UnivAngers, CHU Nantes, INSERM, Regenerative Medicine and Skeleton, RMeS, UMR 1229, F-44000 Nantes, France

d Nantes Université, UnivAngers, CHU Nantes, INSERM, CNRS, CRCI2NA, F-44000 Nantes, France
# Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion: a three-dimensional study

## ABSTRACT

**Introduction** – Surgically assisted rapid maxillary expansion (SARME) with a dental- anchorage appliance can induce dental and skeletal complications adjacent to the teeth supporting the device. The purpose of this study was to quantify the dentoskeletal changes observed after SARME using a tooth-borne device.

**Materials and methods** – Cone beam CT images from 39 patients were compared between the preoperative (T1) and the postoperative period (T2). The mean time to complete the second imaging was 13.8 ± 6.9 months after the SARME. Dental and bone parameters were assessed: the vestibular bone height (BH), the bone thickness (BT), the existence of fenestrations, and the root resorption at the level of first upper premolar (P1) and the first upper molar (M1). The maxillary expansion parameters were also collected.

**Results** – Both vertical and horizontal vestibular bone loss were observed mainly in the first upper molar sectors: The BT decreased from 0.93 ± 0.50 mm to 0.53 ± 0.51 mm (p<0.0001) and the BH decreased from 1.84 ± 1.05 mm to 0.93 ± 1.02 mm (p<0.0001) for tooth #16. The bone loss also affected the first upper premolars but in a more limited manner. Significant fenestrations were observed at the apex of the mesio-vestibular root of teeth #16 and #26. We noted significant root resorption affecting the mesio-, disto-vestibular and palatal roots of tooth #16 (mean reductions of 0.32, 0.35, and 0.55 mm, respectively; p<0.05), and the palatal root of tooth # 26 (loss of 0.58 mm; p=0.004). The mean bone expansion was 3.76 mm and 1.41 mm at the premolar and molar levels, respectively (p<0.0001), while a mean 6.24 mm and 4.23 mm inter-cuspid expansion was noted at the P1 and M1 levels (p<0.0001).

**Conclusion** – Our results document the vestibular bone changes and low root resorption, mostly in the molar sectors, associated with SARME using dental- anchorage devices.

## KEYWORDS

Maxillary expansion; SARME; surgical expansion; dentofacial deformities
# Alveolar bone changes after tooth-borne surgically assisted rapid maxillary expansion: a three-dimensional study

## ABSTRACT

**Introduction** – Surgically assisted rapid maxillary expansion (SARME) with a dental- anchorage appliance can induce dental and skeletal complications adjacent to the teeth supporting the device. The purpose of this study was to quantify the dentoskeletal changes observed after SARME using a tooth-borne device.

**Materials and methods** – Cone beam CT images from 39 patients were compared between the preoperative (T1) and the postoperative period (T2). The mean time to complete the second imaging was 13.8 ± 6.9 months after the SARME. Dental and bone parameters were assessed: the vestibular bone height (BH), the bone thickness (BT), the existence of fenestrations, and the root resorption at the level of first upper premolar (P1) and the first upper molar (M1). The maxillary expansion parameters were also collected.

**Results** – Both vertical and horizontal vestibular bone loss were observed mainly in the first upper molar sectors: The BT decreased from 0.93 ± 0.50 mm to 0.53 ± 0.51 mm (p<0.0001) and the BH decreased from 1.84 ± 1.05 mm to 0.93 ± 1.02 mm (p<0.0001) for tooth #16. The bone loss also affected the first upper premolars but in a more limited manner. Significant fenestrations were observed at the apex of the mesio-vestibular root of teeth #16 and #26. We noted significant root resorption affecting the mesio-, disto-vestibular and palatal roots of tooth #16 (mean reductions of 0.32, 0.35, and 0.55 mm, respectively; p<0.05), and the palatal root of tooth # 26 (loss of 0.58 mm; p=0.004). The mean bone expansion was 3.76 mm and 1.41 mm at the premolar and molar levels, respectively (p<0.0001), while a mean 6.24 mm and 4.23 mm inter-cuspid expansion was noted at the P1 and M1 levels (p<0.0001).

**Conclusion** – Our results document the vestibular bone changes and low root resorption, mostly in the molar sectors, associated with SARME using dental- anchorage devices.

## KEYWORDS

Maxillary expansion; SARME; surgical expansion; dentofacial deformities
# INTRODUCTION

Surgically-assisted rapid maxillary expansion (SARME) is indicated in skeletally mature patients to treat transverse discrepancies greater than 5 mm between the molars [1]. Patients with transverse maxillary deficiency usually have a narrow palatal vault, a unilateral or bilateral crossbite, a constricted maxillary arch, anterior crowding, and buccal corridors when smiling. Such anomalies may represent aesthetic and functional issues for patients [2,3]. The purpose of SARME is to remove skeletal impediments to allow transverse expansion of the maxilla by distraction osteogenesis [4]. The procedure is usually performed early during the orthodontic treatment, under general anesthesia. Although several surgical procedures have been described, most frequently, a sub-total Le Fort I osteotomy is combined with a midpalatal osteotomy and release of the nasal septum [5].

Three types of appliances can be used to expand the maxilla after the surgical procedure: tooth-borne, bone-borne, and hybrid devices. Tooth-anchored appliances have been associated with possible root resorption, vestibular version, periodontal ligament compression, and alveolar bone bending [1,6,7]. Dental complications are usually observed weeks or months after the SARME and mostly concern premolars and molars as these teeth anchor the device [8]. It is important to evaluate the periodontal condition of the anchor teeth to prevent complications. Indeed, excessive vestibular inclination can cause bone dehiscence and thus allow the formation of gingival recessions [2]. Bone-borne devices, by transmitting the forces directly to the bone, can avoid these undesirable effects [4].

Although SARME is commonly used to treat maxillary transverse deficiencies, there is no consensus in the literature regarding which type of expander to use. Furthermore, the results of different studies are sometimes contradictory. In a systematic review comparing bone-borne versus tooth-borne devices, Verstraaten et al. did not find any significant difference in terms of buccal tipping of the teeth [6]. In a comparative study of SARME with tooth-borne versus bone-borne devices, Zandi et al. did not find any significant difference in the incidence of complications between the two devices, and they noted comparable results in terms of skeletal and dental changes [9]. Recent studies have used cone beam computed tomography (CBCT) and validated landmarks as an accurate and reproducible tool to assess dentoskeletal changes after SARME [10].
# INTRODUCTION

Surgically-assisted rapid maxillary expansion (SARME) is indicated in skeletally mature patients to treat transverse discrepancies greater than 5 mm between the molars [1]. Patients with transverse maxillary deficiency usually have a narrow palatal vault, a unilateral or bilateral crossbite, a constricted maxillary arch, anterior crowding, and buccal corridors when smiling. Such anomalies may represent aesthetic and functional issues for patients [2,3]. The purpose of SARME is to remove skeletal impediments to allow transverse expansion of the maxilla by distraction osteogenesis [4]. The procedure is usually performed early during the orthodontic treatment, under general anesthesia. Although several surgical procedures have been described, most frequently, a sub-total Le Fort I osteotomy is combined with a midpalatal osteotomy and release of the nasal septum [5].

Three types of appliances can be used to expand the maxilla after the surgical procedure: tooth-borne, bone-borne, and hybrid devices. Tooth-anchored appliances have been associated with possible root resorption, vestibular version, periodontal ligament compression, and alveolar bone bending [1,6,7]. Dental complications are usually observed weeks or months after the SARME and mostly concern premolars and molars as these teeth anchor the device [8]. It is important to evaluate the periodontal condition of the anchor teeth to prevent complications. Indeed, excessive vestibular inclination can cause bone dehiscence and thus allow the formation of gingival recessions [2]. Bone-borne devices, by transmitting the forces directly to the bone, can avoid these undesirable effects [4].

Although SARME is commonly used to treat maxillary transverse deficiencies, there is no consensus in the literature regarding which type of expander to use. Furthermore, the results of different studies are sometimes contradictory. In a systematic review comparing bone-borne versus tooth-borne devices, Verstraaten et al. did not find any significant difference in terms of buccal tipping of the teeth [6]. In a comparative study of SARME with tooth-borne versus bone-borne devices, Zandi et al. did not find any significant difference in the incidence of complications between the two devices, and they noted comparable results in terms of skeletal and dental changes [9]. Recent studies have used cone beam computed tomography (CBCT) and validated landmarks as an accurate and reproducible tool to assess dentoskeletal changes after SARME [10].
The aim of this study was to precisely describe the dentoskeletal changes observed
on the maxillary first premolars (P1) and the first molars (M1) after tooth-borne
SARME using preoperative and postoperative CBCT analysis.
The aim of this study was to precisely describe the dentoskeletal changes observed
on the maxillary first premolars (P1) and the first molars (M1) after tooth-borne
SARME using preoperative and postoperative CBCT analysis.
# MATERIALS AND METHODS

## Study population

This monocentric, retrospective study included patients who had undergone a SARME to correct a transverse deficiency of the maxillary bone. All of the procedures were carried out in the Department of Maxillofacial and Stomatology Surgery of Nantes University Hospital (France) between January 2010 and January 2020. Throughout this retrospective study, there were no changes to the current clinical practice or the randomization. Due to the retrospective nature of the study, it was formally granted exemption from approval by the ethics committee of Nantes University Hospital in accordance with French legislation article L. 1121-1 paragraph 1 and R1121-2 of the Public Health Code.

The inclusion criteria were:

- a maxillary transverse deficiency of 5 mm or greater between the molar sectors,

- the presence of a posterior crossbite,

- availability of a complete medical file with preoperative CBCT (T1) and after the retention period, when the patient attended a follow-up appointment (T2).

The exclusion criteria were:

- patients with previous orthodontic treatment,

- the presence of a congenital craniofacial syndrome including cleft lip and palate,

- missing first molars.

The patient medical charts were reviewed, and data documenting the age of the patients, their gender, the mean follow-up duration, and potential complications were compiled.

## Treatment protocol

The surgical technique performed was similar to a conventional Le Fort I osteotomy as described by Bell [11], although there were a certain number of minor variations. An upper vestibular or sulcular incision was performed from one canine to the other. A subperiosteal flap then allowed exposure of the emergence of the infraorbital nerve and the pterygomaxillary junction. The nasal floor was lifted upward, and the piriform orifices were often enlarged and lowered to allow better nasal ventilation. After pterygomaxillary disjunction and release of the nasal septum, a horizontal bone
# MATERIALS AND METHODS

## Study population

This monocentric, retrospective study included patients who had undergone a SARME to correct a transverse deficiency of the maxillary bone. All of the procedures were carried out in the Department of Maxillofacial and Stomatology Surgery of Nantes University Hospital (France) between January 2010 and January 2020. Throughout this retrospective study, there were no changes to the current clinical practice or the randomization. Due to the retrospective nature of the study, it was formally granted exemption from approval by the ethics committee of Nantes University Hospital in accordance with French legislation article L. 1121-1 paragraph 1 and R1121-2 of the Public Health Code.

The inclusion criteria were:

- a maxillary transverse deficiency of 5 mm or greater between the molar sectors,

- the presence of a posterior crossbite,

- availability of a complete medical file with preoperative CBCT (T1) and after the retention period, when the patient attended a follow-up appointment (T2).

The exclusion criteria were:

- patients with previous orthodontic treatment,

- the presence of a congenital craniofacial syndrome including cleft lip and palate,

- missing first molars.

The patient medical charts were reviewed, and data documenting the age of the patients, their gender, the mean follow-up duration, and potential complications were compiled.

## Treatment protocol

The surgical technique performed was similar to a conventional Le Fort I osteotomy as described by Bell [11], although there were a certain number of minor variations. An upper vestibular or sulcular incision was performed from one canine to the other. A subperiosteal flap then allowed exposure of the emergence of the infraorbital nerve and the pterygomaxillary junction. The nasal floor was lifted upward, and the piriform orifices were often enlarged and lowered to allow better nasal ventilation. After pterygomaxillary disjunction and release of the nasal septum, a horizontal bone
osteotomy was carried out with an oscillating saw involving the anterior and lateral walls of the maxillary sinus and the pterygoid plates. In most cases, the inter-sinus- nasal septa were left in place, and no downward fracture of the maxilla was performed. A vertical osteotomy passing between the central upper incisors, and performed with thin osteotomes, completed the procedure.

Patients were then treated with two-banded tooth-borne appliances, cemented onto the first molars and premolars, and placed systematically in the days before the surgical procedure. Appliance activation was initiated 7 days postoperatively using two partial revolutions daily. Activation was continued for 2 to 3 weeks, depending on the total amount of expansion needed. A soft food diet was advised during this period.

## Radiographic analysis

Image acquisition was performed before the procedure (T1) and a few months later during the follow-up (T2) using a wide-field CBCT device (NewTom VGi, QR, Verona, Italy). The radiographic measurements were performed by the same examiner on multiplanar reconstruction (MPR) with 0.3 mm cuts using a picture archiving communication system (CARESTREAM® View PACS 12.1, Carestream Health, Inc. 2014, Rochester, USA).

Various parameters were measured on the images:

1. The bone height (BH) and the bone thickness (BT) for P1 and M1. For this analysis, we relied on the work of Chane-Fane and Darque, and Rungcharassaeng et al. [12,13]. In order to obtain a reproducible measurement, the coronal axis of the axial section was positioned perpendicular to the alveolar process (Figure 1). Depending on the tooth studied, the line was placed through the middle of the root for P1 and through the middle of the mesio-vestibular root for M1. On the coronal section obtained, a reference line (RL) was drawn from the vestibular apex to the vestibular cusp for P1, and from the mesio-vestibular apex to the mesio- vestibular cusp for M1. Then two lines were constructed perpendicularly to the RL: the first (PL1) going through the most coronal point of the intersection of the alveolar bone with the tooth; the second (PL2) going through the most vestibular point on the vestibular cortical bone. The distance between PL1 and
osteotomy was carried out with an oscillating saw involving the anterior and lateral walls of the maxillary sinus and the pterygoid plates. In most cases, the inter-sinus- nasal septa were left in place, and no downward fracture of the maxilla was performed. A vertical osteotomy passing between the central upper incisors, and performed with thin osteotomes, completed the procedure.

Patients were then treated with two-banded tooth-borne appliances, cemented onto the first molars and premolars, and placed systematically in the days before the surgical procedure. Appliance activation was initiated 7 days postoperatively using two partial revolutions daily. Activation was continued for 2 to 3 weeks, depending on the total amount of expansion needed. A soft food diet was advised during this period.

## Radiographic analysis

Image acquisition was performed before the procedure (T1) and a few months later during the follow-up (T2) using a wide-field CBCT device (NewTom VGi, QR, Verona, Italy). The radiographic measurements were performed by the same examiner on multiplanar reconstruction (MPR) with 0.3 mm cuts using a picture archiving communication system (CARESTREAM® View PACS 12.1, Carestream Health, Inc. 2014, Rochester, USA).

Various parameters were measured on the images:

1. The bone height (BH) and the bone thickness (BT) for P1 and M1. For this analysis, we relied on the work of Chane-Fane and Darque, and Rungcharassaeng et al. [12,13]. In order to obtain a reproducible measurement, the coronal axis of the axial section was positioned perpendicular to the alveolar process (Figure 1). Depending on the tooth studied, the line was placed through the middle of the root for P1 and through the middle of the mesio-vestibular root for M1. On the coronal section obtained, a reference line (RL) was drawn from the vestibular apex to the vestibular cusp for P1, and from the mesio-vestibular apex to the mesio- vestibular cusp for M1. Then two lines were constructed perpendicularly to the RL: the first (PL1) going through the most coronal point of the intersection of the alveolar bone with the tooth; the second (PL2) going through the most vestibular point on the vestibular cortical bone. The distance between PL1 and
PL2 on the RL was defined as the BH. The BT was defined as the distance
between the root surface and the vestibular cortical bone on PL2 (Figure 1).

2. **Fenestrations.** On the same coronal sections, the presence of fenestration (F) was recorded when present on the vestibular roots of P1 and M1.

3. **External apical root resorption.** On the coronal sections, we measured the distance between the apex and the vestibular dental cusp (Figure 1):
   - of the vestibular root length (VRL) and the palatal root length (PRL) of P1,
   - of the mesio-vestibular root length (MVRL), the disto-vestibular root length (DVRL), and the palatal root length (PRL) of M1.

4. **Maxillary expansion parameters** (Figure 1):
   - The external maxillary width (EMW) was measured on a straight-line tangent to the palatal vault and corresponding to the distance between the external cortical bones with regard to the first upper premolars (EMW4) and the first upper molars (EMW6).
   - The inter-apex distance (IAD) was measured between the two P1 (IAD4) and the two M1 (IAD6)
   - The inter-cuspid distance (ICD) was measured between the two P1 (ICD4) and the two M1 (ICD6)
   - The angle (A4) formed by the straight lines passing through the vestibular cusps and the apex of the P1. The angle had a positive value when the lines converged upwards and a negative value when they converged downwards.
   - The angle (A6) formed by the straight lines passing through the disto-vestibular cusps and the palatal apex of the M1. The angle had a positive value when the lines converged upwards and a negative value when they converged downwards.

**Statistical analysis**

The statistical analysis was performed using GraphPad Prism 9.0 software for Mac (GraphPad Software, La Jolla, CA, USA). The quantitative data were analyzed using a paired t-test. A p-value of less than 0.05 was taken to indicate statistical significance. Fisher's test was used to assess fenestrations. Twenty randomly selected CBCTs were evaluated a second time by the same examiner. The methodical error of the cephalometric measurements was assessed using Dahlberg's formula (mean square error (S.E²) = d²/2n, where d is the difference between the
PL2 on the RL was defined as the BH. The BT was defined as the distance
between the root surface and the vestibular cortical bone on PL2 (Figure 1).

2. **Fenestrations.** On the same coronal sections, the presence of fenestration (F) was recorded when present on the vestibular roots of P1 and M1.

3. **External apical root resorption.** On the coronal sections, we measured the distance between the apex and the vestibular dental cusp (Figure 1):

- of the vestibular root length (VRL) and the palatal root length (PRL) of P1,

- of the mesio-vestibular root length (MVRL), the disto-vestibular root length (DVRL), and the palatal root length (PRL) of M1.

4. **Maxillary expansion parameters** (Figure 1):

- The external maxillary width (EMW) was measured on a straight-line tangent to the palatal vault and corresponding to the distance between the external cortical bones with regard to the first upper premolars (EMW4) and the first upper molars (EMW6).

- The inter-apex distance (IAD) was measured between the two P1 (IAD4) and the two M1 (IAD6)

- The inter-cuspid distance (ICD) was measured between the two P1 (ICD4) and the two M1 (ICD6)

- The angle (A4) formed by the straight lines passing through the vestibular cusps and the apex of the P1. The angle had a positive value when the lines converged upwards and a negative value when they converged downwards.

- The angle (A6) formed by the straight lines passing through the disto-vestibular cusps and the palatal apex of the M1. The angle had a positive value when the lines converged upwards and a negative value when they converged downwards.

**Statistical analysis**

The statistical analysis was performed using GraphPad Prism 9.0 software for Mac (GraphPad Software, La Jolla, CA, USA). The quantitative data were analyzed using a paired t-test. A p-value of less than 0.05 was taken to indicate statistical significance. Fisher's test was used to assess fenestrations. Twenty randomly selected CBCTs were evaluated a second time by the same examiner. The methodical error of the cephalometric measurements was assessed using Dahlberg's formula (mean square error (S.E²) = d²/2n, where d is the difference between the
relapses in the first and the second measurements, and n is the number of double measurements) [14].
relapses in the first and the second measurements, and n is the number of double measurements) [14].
# RESULTS

The medical records of 199 patients who underwent SARME in the Maxillofacial Surgery Department at Nantes University Hospital between 2010 and 2020 were collected. Ninety-one patients were eliminated based on the exclusion criteria: 83 patients had received orthodontic treatment, 7 were followed up for a craniofacial syndrome, and one presented with dental agenesis of the first upper molars. Sixty-nine patients were secondarily excluded due to a lack of radiological data (41 and 28 for missing postoperative and preoperative CBCT, respectively). Thirty-nine patients were ultimately included in the study (25 females and 14 males). The patients ranged from 12 to 48 years of age (mean 25.9 ± 9.2 years). The postoperative CBCT was carried out on average 13.8 ± 6.9 months after the surgical procedure.

## Efficacy of the SARME

The degree of maxillary expansion was determined by various parameters. Changes were observed in external maxillary width, particularly regarding the first premolars: bone expansion increased from 36.66 ± 4.31 mm to 40.42 ± 4.63 mm for EMW4 (p<0.0001). A more moderate variation was observed for EMW6 (Table 1). The inter-apex distance increased significantly between the preoperative and the postoperative period at both the premolar and the molar levels (Table 1). The inter-cuspid distance increased more (Table 1). The mean Dahlberg standard error for these measurements was 0.59 ± 1.23 for EMW and 2.00 ± 8.05 for the IAD and ICD, respectively.

<table><caption>Table 1. Changes in maxillary transversal dimension between T1 and T2. EMW, external maxillary width; IAD, inter-apex distance; ICD, inter-cuspid distance; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>External maxillary width, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>EMW4</td><td>36.66 ± 4.31</td><td>40.42 ± 4.63</td><td>&lt; 0.0001</td></tr><tr><td>EMW6</td><td>58.32 ± 4.85</td><td>59.73 ± 4.80</td><td>&lt; 0.0001</td></tr><tr><td>Inter-apex distance, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>IAD4</td><td>35.12 ± 4.26</td><td>38.07 ± 4.19</td><td>&lt; 0.0001</td></tr><tr><td>IAD6</td><td>31.27 ± 3.62</td><td>35.33 ± 4.39</td><td>&lt; 0.0001</td></tr><tr><td>Inter-cuspid distance, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>ICD4</td><td>37.71 ± 3.80</td><td>43.95 ± 2.70</td><td>&lt; 0.0001</td></tr><tr><td>ICD6</td><td>49.85 ± 3.80</td><td>54.08 ± 3.76</td><td>&lt; 0.0001</td></tr></tbody></table>
# RESULTS

The medical records of 199 patients who underwent SARME in the Maxillofacial Surgery Department at Nantes University Hospital between 2010 and 2020 were collected. Ninety-one patients were eliminated based on the exclusion criteria: 83 patients had received orthodontic treatment, 7 were followed up for a craniofacial syndrome, and one presented with dental agenesis of the first upper molars. Sixty-nine patients were secondarily excluded due to a lack of radiological data (41 and 28 for missing postoperative and preoperative CBCT, respectively). Thirty-nine patients were ultimately included in the study (25 females and 14 males). The patients ranged from 12 to 48 years of age (mean 25.9 ± 9.2 years). The postoperative CBCT was carried out on average 13.8 ± 6.9 months after the surgical procedure.

## Efficacy of the SARME

The degree of maxillary expansion was determined by various parameters. Changes were observed in external maxillary width, particularly regarding the first premolars: bone expansion increased from 36.66 ± 4.31 mm to 40.42 ± 4.63 mm for EMW4 (p<0.0001). A more moderate variation was observed for EMW6 (Table 1). The inter-apex distance increased significantly between the preoperative and the postoperative period at both the premolar and the molar levels (Table 1). The inter-cuspid distance increased more (Table 1). The mean Dahlberg standard error for these measurements was 0.59 ± 1.23 for EMW and 2.00 ± 8.05 for the IAD and ICD, respectively.

<table><caption>Table 1. Changes in maxillary transversal dimension between T1 and T2. EMW, external maxillary width; IAD, inter-apex distance; ICD, inter-cuspid distance; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>External maxillary width, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>EMW4</td><td>36.66 ± 4.31</td><td>40.42 ± 4.63</td><td>&lt; 0.0001</td></tr><tr><td>EMW6</td><td>58.32 ± 4.85</td><td>59.73 ± 4.80</td><td>&lt; 0.0001</td></tr><tr><td>Inter-apex distance, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>IAD4</td><td>35.12 ± 4.26</td><td>38.07 ± 4.19</td><td>&lt; 0.0001</td></tr><tr><td>IAD6</td><td>31.27 ± 3.62</td><td>35.33 ± 4.39</td><td>&lt; 0.0001</td></tr><tr><td>Inter-cuspid distance, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>ICD4</td><td>37.71 ± 3.80</td><td>43.95 ± 2.70</td><td>&lt; 0.0001</td></tr><tr><td>ICD6</td><td>49.85 ± 3.80</td><td>54.08 ± 3.76</td><td>&lt; 0.0001</td></tr></tbody></table>
### Radiographic changes (primary outcomes)

Significant changes occurred in the BH and BT between T1 and T2. We observed a 33% to 43% decrease in the BT in the molar sectors, ranging from 0.93 ± 0.50 mm to 0.53 ± 0.51mm for tooth #16 and from 0.95 ± 0.53 mm to 0.63 ± 0.60 mm for tooth #26 (p<0.0001). A mean of 21% to 23% of bone loss was noted for the premolar sectors (Table 2). The BH was also significantly reduced, particularly regarding the molar sectors, with a mean of 49.5% of bone loss for tooth #16 and 35.7% for tooth #26. The bone height loss was less significant for the premolars (Table 2). The mean Dahlberg standard errors for the BH and the BT were 0.219 ± 0.35 mm and 0.044 ± 0.55 mm, respectively.

<table><caption>Table 2. Comparison of the bone thickness and the bone height in the premolar and molar sectors between T1 and T2. BT, bone thickness; BH, bone height; 14, right upper first premolar; 24, left upper first premolar; 16, right first upper molar; 26, left first upper molar; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>Bone thickness, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>BT14</td><td>1.10 ± 0.48</td><td>0.87 ± 0.61</td><td>0.011</td></tr><tr><td>BT24</td><td>1.04 ± 0.48</td><td>0.8 ± 0.56</td><td>0.006</td></tr><tr><td>BT16</td><td>0.93 ± 0.50</td><td>0.53 ± 0.51</td><td>&lt; 0.0001</td></tr><tr><td>BT26</td><td>0.95 ± 0.53</td><td>0.63 ± 0.60</td><td>&lt; 0.0001</td></tr><tr><td>Bone height, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>BH14</td><td>1.94 ± 0.85</td><td>1.59 ± 1.04</td><td>0.063</td></tr><tr><td>BH24</td><td>1.55 ± 0.64</td><td>1.26 ± 0.86</td><td>0.044</td></tr><tr><td>BH16</td><td>1.84 ± 1.05</td><td>0.93 ± 1.02</td><td>&lt; 0.0001</td></tr><tr><td>BH26</td><td>1.43 ± 0.83</td><td>0.92 ± 1.04</td><td>0.0007</td></tr></tbody></table>

With regard to the fenestrations, we noted a tendency for these to increase, particularly in the molar sectors at the apex of the meso-vestibular root of tooth #16 and tooth #26, with the mean number of impacted teeth ranging from 5 to 13 for MVF16 and from 3 to 11 for MVF26 (p₁=0.05 and p₂=0.03, respectively) (Table 3).

<table><caption>Table 3. Comparison of fenestrations at T1 and T2. F, fenestration: MV, meso-vestibular; DV, disto-vestibular.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>F14</td><td>3</td><td>9</td><td>0.114</td></tr><tr><td>F24</td><td>3</td><td>9</td><td>0.114</td></tr><tr><td>MVF16</td><td>5</td><td>13</td><td>0.058</td></tr><tr><td>DVF16</td><td>3</td><td>8</td><td>0.191</td></tr><tr><td>MVF26</td><td>3</td><td>11</td><td>0.036</td></tr><tr><td>DVF26</td><td>1</td><td>4</td><td>0.358</td></tr></tbody></table>
### Radiographic changes (primary outcomes)

Significant changes occurred in the BH and BT between T1 and T2. We observed a 33% to 43% decrease in the BT in the molar sectors, ranging from 0.93 ± 0.50 mm to 0.53 ± 0.51mm for tooth #16 and from 0.95 ± 0.53 mm to 0.63 ± 0.60 mm for tooth #26 (p<0.0001). A mean of 21% to 23% of bone loss was noted for the premolar sectors (Table 2). The BH was also significantly reduced, particularly regarding the molar sectors, with a mean of 49.5% of bone loss for tooth #16 and 35.7% for tooth #26. The bone height loss was less significant for the premolars (Table 2). The mean Dahlberg standard errors for the BH and the BT were 0.219 ± 0.35 mm and 0.044 ± 0.55 mm, respectively.

<table><caption>Table 2. Comparison of the bone thickness and the bone height in the premolar and molar sectors between T1 and T2. BT, bone thickness; BH, bone height; 14, right upper first premolar; 24, left upper first premolar; 16, right first upper molar; 26, left first upper molar; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>Bone thickness, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>BT14</td><td>1.10 ± 0.48</td><td>0.87 ± 0.61</td><td>0.011</td></tr><tr><td>BT24</td><td>1.04 ± 0.48</td><td>0.8 ± 0.56</td><td>0.006</td></tr><tr><td>BT16</td><td>0.93 ± 0.50</td><td>0.53 ± 0.51</td><td>&lt; 0.0001</td></tr><tr><td>BT26</td><td>0.95 ± 0.53</td><td>0.63 ± 0.60</td><td>&lt; 0.0001</td></tr><tr><td>Bone height, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>BH14</td><td>1.94 ± 0.85</td><td>1.59 ± 1.04</td><td>0.063</td></tr><tr><td>BH24</td><td>1.55 ± 0.64</td><td>1.26 ± 0.86</td><td>0.044</td></tr><tr><td>BH16</td><td>1.84 ± 1.05</td><td>0.93 ± 1.02</td><td>&lt; 0.0001</td></tr><tr><td>BH26</td><td>1.43 ± 0.83</td><td>0.92 ± 1.04</td><td>0.0007</td></tr></tbody></table>

With regard to the fenestrations, we noted a tendency for these to increase, particularly in the molar sectors at the apex of the meso-vestibular root of tooth #16 and tooth #26, with the mean number of impacted teeth ranging from 5 to 13 for MVF16 and from 3 to 11 for MVF26 (p₁=0.05 and p₂=0.03, respectively) (Table 3).

<table><caption>Table 3. Comparison of fenestrations at T1 and T2. F, fenestration: MV, meso-vestibular; DV, disto-vestibular.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>F14</td><td>3</td><td>9</td><td>0.114</td></tr><tr><td>F24</td><td>3</td><td>9</td><td>0.114</td></tr><tr><td>MVF16</td><td>5</td><td>13</td><td>0.058</td></tr><tr><td>DVF16</td><td>3</td><td>8</td><td>0.191</td></tr><tr><td>MVF26</td><td>3</td><td>11</td><td>0.036</td></tr><tr><td>DVF26</td><td>1</td><td>4</td><td>0.358</td></tr></tbody></table>
To investigate the root resorption associated with SARME, we measured the distance between the dental apex and the vestibular/palatal cusps of P1 and M1 on both sides. We did not observe any significant difference in the root length in the premolar regions (Table 4). Whereas significant root shortening was observed in the mesio-, disto-vestibular, and palatal roots of tooth #16 (Table 4). The mean Dahlberg standard error for the root measurement was 0.163 ± 0.31.

<table><caption>Table 4. Comparison of the root length in the premolar and molar sectors between T1 and T2. VRL, vestibular root length; PRL, palatal root length; MVRL, mesio-vestibular root length; DVRL, disto-vestibular root length; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>Premolar root length, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>VRL14</td><td>20.54 ± 2.22</td><td>20.34 ± 2.08</td><td>0.170</td></tr><tr><td>PRL14</td><td>18.81 ± 2.42</td><td>18.56 ± 2.32</td><td>0.260</td></tr><tr><td>VRL24</td><td>20.61 ± 2.04</td><td>20.43 ± 2.30</td><td>0.300</td></tr><tr><td>PRL24</td><td>18.93 ± 2.16</td><td>18.85 ± 2.37</td><td>0.710</td></tr><tr><td>Molar root length, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>MVRL16</td><td>19.24 ± 1.86</td><td>18.92 ± 1.75</td><td>0.032</td></tr><tr><td>DVRL16</td><td>18.82 ± 1.79</td><td>18.47 ± 1.72</td><td>0.027</td></tr><tr><td>PRL16</td><td>20.66 ± 2.09</td><td>20.11 ± 2.17</td><td>0.002</td></tr><tr><td>MVRL6</td><td>18.84 ± 1.56</td><td>18.79 ± 1.73</td><td>0.673</td></tr><tr><td>DVRL26</td><td>18.7 ± 1.59</td><td>18.50 ± 1.54</td><td>0.160</td></tr><tr><td>PRL26</td><td>20.56 ± 2.01</td><td>19.98 ± 2.16</td><td>0.004</td></tr></tbody></table>

### Others results

A significant change was observed in angle A4, which increased from 7.38 ± 14.98 degrees to 17.61 ± 13.19 degrees (p<0.0001). A slight increase was noted regarding angle A6 formed by the first upper molars (increasing from 52.96 ± 11.97 degrees to 54.52 ± 10.43 degrees; p=0.34). The mean Dahlberg error for the angle measurement was 2.16 ± 4.96 degrees.

Five minor complications were noted after the surgical procedure: Three patients complained of hypoesthesia of the superior lip or loss of dental sensitivity in the central upper incisors, with total recovery at 6 months. One patient suffered from signs of dental necrosis of tooth #11, with permanent dyschromia. One patient presented immediate postoperative epistaxis, with spontaneous recovery.
To investigate the root resorption associated with SARME, we measured the distance between the dental apex and the vestibular/palatal cusps of P1 and M1 on both sides. We did not observe any significant difference in the root length in the premolar regions (Table 4). Whereas significant root shortening was observed in the mesio-, disto-vestibular, and palatal roots of tooth #16 (Table 4). The mean Dahlberg standard error for the root measurement was 0.163 ± 0.31.

<table><caption>Table 4. Comparison of the root length in the premolar and molar sectors between T1 and T2. VRL, vestibular root length; PRL, palatal root length; MVRL, mesio-vestibular root length; DVRL, disto-vestibular root length; SD, standard deviation.</caption><thead><tr><th></th><th>T1</th><th>T2</th><th>p-value</th></tr></thead><tbody><tr><td>Premolar root length, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>VRL14</td><td>20.54 ± 2.22</td><td>20.34 ± 2.08</td><td>0.170</td></tr><tr><td>PRL14</td><td>18.81 ± 2.42</td><td>18.56 ± 2.32</td><td>0.260</td></tr><tr><td>VRL24</td><td>20.61 ± 2.04</td><td>20.43 ± 2.30</td><td>0.300</td></tr><tr><td>PRL24</td><td>18.93 ± 2.16</td><td>18.85 ± 2.37</td><td>0.710</td></tr><tr><td>Molar root length, mean ± SD</td><td></td><td></td><td></td></tr><tr><td>MVRL16</td><td>19.24 ± 1.86</td><td>18.92 ± 1.75</td><td>0.032</td></tr><tr><td>DVRL16</td><td>18.82 ± 1.79</td><td>18.47 ± 1.72</td><td>0.027</td></tr><tr><td>PRL16</td><td>20.66 ± 2.09</td><td>20.11 ± 2.17</td><td>0.002</td></tr><tr><td>MVRL6</td><td>18.84 ± 1.56</td><td>18.79 ± 1.73</td><td>0.673</td></tr><tr><td>DVRL26</td><td>18.7 ± 1.59</td><td>18.50 ± 1.54</td><td>0.160</td></tr><tr><td>PRL26</td><td>20.56 ± 2.01</td><td>19.98 ± 2.16</td><td>0.004</td></tr></tbody></table>

### Others results

A significant change was observed in angle A4, which increased from 7.38 ± 14.98 degrees to 17.61 ± 13.19 degrees (p<0.0001). A slight increase was noted regarding angle A6 formed by the first upper molars (increasing from 52.96 ± 11.97 degrees to 54.52 ± 10.43 degrees; p=0.34). The mean Dahlberg error for the angle measurement was 2.16 ± 4.96 degrees.

Five minor complications were noted after the surgical procedure: Three patients complained of hypoesthesia of the superior lip or loss of dental sensitivity in the central upper incisors, with total recovery at 6 months. One patient suffered from signs of dental necrosis of tooth #11, with permanent dyschromia. One patient presented immediate postoperative epistaxis, with spontaneous recovery.
DISCUSSION

Very few studies to date have focused on vestibular bone changes in posterior teeth after SARME [15-17]. The purpose of this study was to accurately quantify the effects of maxillary expansion on the alveolar bone involving the use of dental anchorage devices. The accuracy and reproducibility of measurements on CBCT images have been shown to be greater than on conventional 2D radiographs [18]. Moreover, CBCT analysis is a reliable method for evaluation of dental and skeletal changes in the maxilla after SARME, through specific landmarks, without the superimposition of structures or distortion [19]. For this reason, we based our study on radiographic analysis of different bone and dental landmarks. We included 39 patients, which is more than most of the studies that have reported on this issue [15-17]. Most of the patients in our observation period had to be excluded because of previous orthodontic treatment, mostly in childhood, with recurrence of the dentofacial deformities. The other reason for excluding patients was the lack of pre-or post-operative imaging because, although cone beam CT is now widely used and performed pre-operatively, there is no consensus on whether to perform a post-operative examination. The mean age of the patients was 25.9 years, which is in line with the literature, which reports that patients submitted to SARME are often between 19 and 29 years of age [20]. Indeed, SARME is generally indicated for transverse maxillary hypoplasia and/or crowding of teeth in skeletally mature patients [1]. We observed a significant decrease in bone thickness at the P1 and M1 levels, reaching 0.40 mm for tooth #16. Our results are in agreement with the literature, which reports bone loss of 0.4 to 1 mm on molar sectors [15-17]. The bone height was also reduced after the surgical procedure, particularly regarding the first upper molars; in coherence with other publications [16,17]. We can assume that vestibular bone resorption, either horizontally or vertically, is more pronounced on the molar sectors because they support the appliance and are, therefore subject, to expansion forces. However, we did not observe complete bone loss, and no correlation with a clinical outcome (tooth mobility, gingival retraction) could be established at this stage.

Alveolar fenestration can be defined by a circumscribed defect of the cortical plate that exposes the underlying root surface but does not involve the alveolar margin of the bone [21]. Although fenestrations are encountered in patients without orthodontic treatment, it is widely assumed that application of an orthopedic appliance increases the risk of fenestration, particularly regarding the maxilla [22,23]. Therefore, we
DISCUSSION

Very few studies to date have focused on vestibular bone changes in posterior teeth after SARME [15–17]. The purpose of this study was to accurately quantify the effects of maxillary expansion on the alveolar bone involving the use of dental- anchorage devices. The accuracy and reproducibility of measurements on CBCT images have been shown to be greater than on conventional 2D radiographs [18]. Moreover, CBCT analysis is a reliable method for evaluation of dental and skeletal changes in the maxilla after SARME, through specific landmarks, without the superimposition of structures or distortion [19]. For this reason, we based our study on radiographic analysis of different bone and dental landmarks. We included 39 patients, which is more than most of the studies that have reported on this issue [15– 17]. Most of the patients in our observation period had to be excluded because of previous orthodontic treatment, mostly in childhood, with recurrence of the dentofacial deformities. The other reason for excluding patients was the lack of pre- or post-operative imaging because, although cone beam CT is now widely used and performed pre-operatively, there is no consensus on whether to perform a post- operative examination. The mean age of the patients was 25.9 years, which is in line with the literature, which reports that patients submitted to SARME are often between 19 and 29 years of age [20]. Indeed, SARME is generally indicated for transverse maxillary hypoplasia and/or crowding of teeth in skeletally mature patients [1]. We observed a significant decrease in bone thickness at the P1 and M1 levels, reaching 0.40 mm for tooth #16. Our results are in agreement with the literature, which reports bone loss of 0.4 to 1 mm on molar sectors [15–17]. The bone height was also reduced after the surgical procedure, particularly regarding the first upper molars; in coherence with other publications [16,17]. We can assume that vestibular bone resorption, either horizontally or vertically, is more pronounced on the molar sectors because they support the appliance and are, therefore subject, to expansion forces. However, we did not observe complete bone loss, and no correlation with a clinical outcome (tooth mobility, gingival retraction) could be established at this stage.

Alveolar fenestration can be defined by a circumscribed defect of the cortical plate that exposes the underlying root surface but does not involve the alveolar margin of the bone [21]. Although fenestrations are encountered in patients without orthodontic treatment, it is widely assumed that application of an orthopedic appliance increases the risk of fenestration, particularly regarding the maxilla [22,23]. Therefore, we
excluded patients who had previously undergone orthodontic treatment. Our study
revealed an increase in the number of cases of fenestration on the postoperative
observation, particularly regarding the mesio-vestibular root of the first upper molars.
In a radiographic comparative study, Romano et al. did not find evidence of an
increase in fenestrations after SARME, irrespective of the teeth studied (canines,
premolars, and molars) [22]. The authors further showed that the presence of
fenestrations on the preoperative evaluation was a significant predictor for the
development of dehiscence in the postoperative and the after-retention periods [22].
While this was not measured in our study, it is commonly accepted that assessment
of alveolar defects is necessary before commencing any orthodontic or surgical
treatment [23,24]. However, other causes, such as insufficient oral hygiene, may
contribute to fenestrations and dehiscence. Furthermore, some authors argue that
fenestrations are hard to diagnose or may be overestimated in CBCT images [25,26].
One of the biases in the measurement of bone defects is that the postoperative cone
beam imaging was sometimes performed after the start of the retention phase. So,
we can assume that some fenestrations healed if the dental apex were repositioned
in the cortex if orthodontic movements were initiated, thus underestimating the
number of fenestrations. Although the root length of the premolars was not impacted
by SARME, those of the upper first molars were significantly reduced after the
procedure. Our results are at the lower range of those observed by Kayalar et al.,
who noted a loss of 0.3 to 1mm in the maxillary molar sector [15]. These authors also
reported more resorption on the palatal root of the maxillary molars [15]. While these
root resorptions are significant, they appear to be too small to have a discernible
clinical impact. In comparison, resorptions related to orthodontic treatment are
considered to be low to moderate when less than 2.5 mm, which may concern 48%
to 66% of the teeth treated orthodontically [27]. Our results could be distorted
because orthodontic movements could have started by the time the second CBCT
was performed. In a systematic review of root resorption, Alqahtani et al. highlighted
that the percentage of teeth affected by root resorption varied between 1% and 36%,
with a higher risk found after SARME [28]. While most studies use 2D imaging to
assess root resorption, we chose to use CBCT imaging for greater accuracy. It is well
established that the risks of human error and observer variability are influenced most
by the landmark-line-based measurement than the imaging modality [29]; for this
reason, we used the Dahlberg standard error on double measurements to express
this measurement error.
excluded patients who had previously undergone orthodontic treatment. Our study
revealed an increase in the number of cases of fenestration on the postoperative
observation, particularly regarding the mesio-vestibular root of the first upper molars.
In a radiographic comparative study, Romano et al. did not find evidence of an
increase in fenestrations after SARME, irrespective of the teeth studied (canines,
premolars, and molars) [22]. The authors further showed that the presence of
fenestrations on the preoperative evaluation was a significant predictor for the
development of dehiscence in the postoperative and the after-retention periods [22].
While this was not measured in our study, it is commonly accepted that assessment
of alveolar defects is necessary before commencing any orthodontic or surgical
treatment [23,24]. However, other causes, such as insufficient oral hygiene, may
contribute to fenestrations and dehiscence. Furthermore, some authors argue that
fenestrations are hard to diagnose or may be overestimated in CBCT images [25,26].
One of the biases in the measurement of bone defects is that the postoperative cone
beam imaging was sometimes performed after the start of the retention phase. So,
we can assume that some fenestrations healed if the dental apex were repositioned
in the cortex if orthodontic movements were initiated, thus underestimating the
number of fenestrations. Although the root length of the premolars was not impacted
by SARME, those of the upper first molars were significantly reduced after the
procedure. Our results are at the lower range of those observed by Kayalar et al.,
who noted a loss of 0.3 to 1mm in the maxillary molar sector [15]. These authors also
reported more resorption on the palatal root of the maxillary molars [15]. While these
root resorptions are significant, they appear to be too small to have a discernible
clinical impact. In comparison, resorptions related to orthodontic treatment are
considered to be low to moderate when less than 2.5 mm, which may concern 48%
to 66% of the teeth treated orthodontically [27]. Our results could be distorted
because orthodontic movements could have started by the time the second CBCT
was performed. In a systematic review of root resorption, Alqahtani et al. highlighted
that the percentage of teeth affected by root resorption varied between 1% and 36%,
with a higher risk found after SARME [28]. While most studies use 2D imaging to
assess root resorption, we chose to use CBCT imaging for greater accuracy. It is well
established that the risks of human error and observer variability are influenced most
by the landmark-line-based measurement than the imaging modality [29]; for this
reason, we used the Dahlberg standard error on double measurements to express
this measurement error.
The other results of our study related to the skeletal expansion obtained with SARME which was a mean of 3.8 mm between the first upper premolars and reduced to 1.4 mm with regard to the external maxillary width on the first upper molars sectors. In a systematic review of stability after SARME, Gogna et al. reported a mean skeletal expansion of 2.3 to 3.1 mm [30]. In the same study, the authors reported an expansion at the inter-canine level of 4–6 mm and 6–8.9 mm at the inter-molar region [30]. Our results are in line with these data, as we found an increase of 6.2 mm in the inter-cuspid diameter on P1 and 4.2 mm on M1. Another study reported a 1.47 ± 0.64 mm expansion at P1 and 3.70 ± 1.52 mm at M1 after SARME [31]. Other results indicate a V-shaped expansion pattern, with greater expansion at the nasal level than in the posterior sectors [32,33]. One of the factors explaining the diversity of results is the numerous osteotomy techniques used, some with lowering of the maxilla allowing splitting of the posterior wall of the maxilla, some passing through the nasal cavities on both sides of the septum to increase the maxillary enlargement. What is certain is that despite the pterygomaxillary osteotomy, the maxilla remains strongly attached in its posterior portion, which may partially explain the lack of transverse expansion at this level. Furthermore, dental or dentoalveolar points are generally used to measure posterior expansion. However, these points are affected by buccal alveolar bending and do not reflect the skeletal expansion, making comparison difficult between the studies [34]. Relapse was not investigated in our study, although our second imaging procedure was often performed during the retention phase. The relapse rate is estimated to be 0.1 to 2.3 mm at the inter-canine dimension and 0.2 to 3 mm at the inter-molar level [30]. The stability appears to be highly influenced by the post-orthodontic phase in which arch coordination is achieved, and alignment and final vertical adjustments are carried out [35]. Regarding dental movements, the distance between the cusps of P1 increased twice as much as the distance between their apexes. In addition, the angle formed by the first upper premolars increased significantly between the preoperative and the postoperative period. The coronovestibular version of the anchored teeth is a classical effect observed with tooth-borne devices [15]. Gradual straightening of the teeth is usually achieved with the retention phase. We reported a low rate of surgical complications, mostly consisting of sensory disorders in the operated area, with spontaneous recovery. In a systematic review, Muños-Pereira et al. highlighted a higher risk of bone resorption with tooth-borne devices compared to bone-borne appliances [35]. Other frequent
The other results of our study related to the skeletal expansion obtained with SARME which was a mean of 3.8 mm between the first upper premolars and reduced to 1.4 mm with regard to the external maxillary width on the first upper molars sectors. In a systematic review of stability after SARME, Gogna *et al.* reported a mean skeletal expansion of 2.3 to 3.1 mm [30]. In the same study, the authors reported an expansion at the inter-canine level of 4–6 mm and 6–8.9 mm at the inter-molar region [30]. Our results are in line with these data, as we found an increase of 6.2 mm in the inter-cuspid diameter on P1 and 4.2 mm on M1. Another study reported a 1.47 ± 0.64 mm expansion at P1 and 3.70 ± 1.52 mm at M1 after SARME [31]. Other results indicate a V-shaped expansion pattern, with greater expansion at the nasal level than in the posterior sectors [32,33]. One of the factors explaining the diversity of results is the numerous osteotomy techniques used, some with lowering of the maxilla allowing splitting of the posterior wall of the maxilla, some passing through the nasal cavities on both sides of the septum to increase the maxillary enlargement. What is certain is that despite the pterygomaxillary osteotomy, the maxilla remains strongly attached in its posterior portion, which may partially explain the lack of transverse expansion at this level. Furthermore, dental or dentoalveolar points are generally used to measure posterior expansion. However, these points are affected by buccal alveolar bending and do not reflect the skeletal expansion, making comparison difficult between the studies [34]. Relapse was not investigated in our study, although our second imaging procedure was often performed during the retention phase. The relapse rate is estimated to be 0.1 to 2.3 mm at the inter-canine dimension and 0.2 to 3 mm at the inter-molar level [30]. The stability appears to be highly influenced by the post-orthodontic phase in which arch coordination is achieved, and alignment and final vertical adjustments are carried out [35]. Regarding dental movements, the distance between the cusps of P1 increased twice as much as the distance between their apexes. In addition, the angle formed by the first upper premolars increased significantly between the preoperative and the postoperative period. The coronovestibular version of the anchored teeth is a classical effect observed with tooth-borne devices [15]. Gradual straightening of the teeth is usually achieved with the retention phase. We reported a low rate of surgical complications, mostly consisting of sensory disorders in the operated area, with spontaneous recovery. In a systematic review, Muños-Pereira *et al.* highlighted a higher risk of bone resorption with tooth-borne devices compared to bone-borne appliances [35]. Other frequent
surgical complications include pain, nasal bleeding, tooth discoloration, and gingival recession [35,36].

Our study suffers from some limitations. The first relates to the retrospective nature of the study, including the different time points for CBCT imaging, which ranged from 6 to 25 months after the surgical procedure. Only one examiner performed the measurements, but the intra-observer error was assessed by the Dahlberg score. Another limitation relates to the landmarks that we chose for measurement of the EMW, as the highest point of the hard palate, the nasal septum, and the shape of the palatal arch can be modified by the procedure. Finally, the lack of simultaneous clinical evaluation of the results regarding occlusion, inter-arch concordance, and signs of bone resorption (tooth mobility, periodontium) precludes assessment of the clinical consequences of the dentoskeletal changes after SARME.

We have noted very heterogeneous methods for measurement of the changes in skeletal parameters after SARME. This represents an obvious obstacle to the comparison of results. Further randomized control trials with long-term results are needed to address the main question related to SARME: 1/ Which appliance allows the best results to be achieved with the least amount of bone and dental resorption? 2/ What is the best activation protocol? 3/ Which surgical technique allows for maximum expansion while also reducing complications?
surgical complications include pain, nasal bleeding, tooth discoloration, and gingival recession [35,36].

Our study suffers from some limitations. The first relates to the retrospective nature of the study, including the different time points for CBCT imaging, which ranged from 6 to 25 months after the surgical procedure. Only one examiner performed the measurements, but the intra-observer error was assessed by the Dahlberg score. Another limitation relates to the landmarks that we chose for measurement of the EMW, as the highest point of the hard palate, the nasal septum, and the shape of the palatal arch can be modified by the procedure. Finally, the lack of simultaneous clinical evaluation of the results regarding occlusion, inter-arch concordance, and signs of bone resorption (tooth mobility, periodontium) precludes assessment of the clinical consequences of the dentoskeletal changes after SARME.

We have noted very heterogeneous methods for measurement of the changes in skeletal parameters after SARME. This represents an obvious obstacle to the comparison of results. Further randomized control trials with long-term results are needed to address the main question related to SARME: 1/ Which appliance allows the best results to be achieved with the least amount of bone and dental resorption? 2/ What is the best activation protocol? 3/ Which surgical technique allows for maximum expansion while also reducing complications?
CONCLUSION

Our study adds to the limited data in the literature related to objective measurement
of the dentoskeletal changes after SARME using dental-anchorage devices. Our
results support the trend of vestibular bone resorption and root resorption mostly in
the upper molar sectors.
CONCLUSION

Our study adds to the limited data in the literature related to objective measurement
of the dentoskeletal changes after SARME using dental-anchorage devices. Our
results support the trend of vestibular bone resorption and root resorption mostly in
the upper molar sectors.
BIBLIOGRAPHY

[1] Koudstaal MJ, Poort LJ, van der Wal KGH, Wolvius EB, Prahl-Andersen B, Schulten AJM. Surgically assisted rapid maxillary expansion (SARME): a review of the literature. Int J Oral Maxillofac Surg 2005;34:709-14.
https://doi.org/10.1016/j.ijom.2005.04.025.

[2] Suri L, Taneja P. Surgically assisted rapid palatal expansion: A literature review. Am J Orthod Dentofacial Orthop 2008;133:290-302.
https://doi.org/10.1016/j.ajodo.2007.01.021.

[3] McNamaraa JA. Maxillary transverse deficiency. Am J Orthod Dentofacial Orthop 2000;117:567-70. https://doi.org/10.1016/S0889-5406(00)70202-2.

[4] Mommaerts MY. Transpalatal distraction as a method of maxillary expansion. Br J Oral Maxillofac Surg 1999;37:268-72. https://doi.org/10.1054/bjom.1999.0127.

[5] Betts NJ, Vanarsdall RL, Barber HD, Higgins-Barber K, Fonseca RJ. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:75-96.

[6] Verstraaten J, Kuijpers-Jagtman AM, Mommaerts MY, Bergé SJ, Nada RM, Schols JGJH, et al. A systematic review of the effects of bone-borne surgical assisted rapid maxillary expansion. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2010;38:166-74.
https://doi.org/10.1016/j.jcms.2009.06.006.

[7] Harzer W, Schneider M, Gedrange T, Tausche E. Direct bone placement of the hyrax fixation screw for surgically assisted rapid palatal expansion (SARPE). J Oral Maxillofac Surg Off J Am Assoc Oral Maxillofac Surg 2006;64:1313-7.
https://doi.org/10.1016/j.joms.2005.11.061.

[8] Williams BJD, Currimbhoy S, Silva A, O'Ryan FS. Complications following surgically assisted rapid palatal expansion: a retrospective cohort study. J Oral Maxillofac Surg Off J Am Assoc Oral Maxillofac Surg 2012;70:2394-402.
https://doi.org/10.1016/j.joms.2011.09.050.

[9] Zandi M, Miresmaeili A, Heidari A. Short-term skeletal and dental changes following bone-borne versus tooth-borne surgically assisted rapid maxillary expansion: A randomized clinical trial study. J Cranio-Maxillofac Surg 2014;42:1190-5. https://doi.org/10.1016/j.jcms.2014.02.007.

[10] Scarfe WC, Farman AG, Sukovic P. Clinical applications of cone-beam computed tomography in dental practice. J Can Dent Assoc 2006;72:75-80.

[11] Bell WH. Le Forte I osteotomy for correction of maxillary deformities. J Oral Surg Am Dent Assoc 1965 1975;33:412-26.

[12] Chane-Fane C, Darqué F. Rapid maxillary expansion assisted by palatal mini-implants in adolescents - preliminary study. Int Orthod 2015;13:96-111.
https://doi.org/10.1016/j.ortho.2014.12.001.

[13] Rungcharassaeng K, Caruso JM, Kan JYK, Kim J, Taylor G. Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion. Am J Orthod Dentofacial Orthop 2007;132:428.e1-428.e8.
https://doi.org/10.1016/j.ajodo.2007.02.052.

[14] Dahlberg G. Statistical methods for medical and biological students. Stat Methods Med Biol Stud 1940.

[15] Kayalar E, Schauseil M, Kuvat SV, Emekli U, Fıratlı S. Comparison of tooth-borne and hybrid devices in surgically assisted rapid maxillary expansion: A randomized clinical cone-beam computed tomography study. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2016;44:285-93.
https://doi.org/10.1016/j.jcms.2015.12.001.
BIBLIOGRAPHY

[1] Koudstaal MJ, Poort LJ, van der Wal KGH, Wolvius EB, Prahl-Andersen B, Schulten AJM. Surgically assisted rapid maxillary expansion (SARME): a review of the literature. Int J Oral Maxillofac Surg 2005;34:709-14.
https://doi.org/10.1016/j.ijom.2005.04.025.

[2] Suri L, Taneja P. Surgically assisted rapid palatal expansion: A literature review. Am J Orthod Dentofacial Orthop 2008;133:290-302.
https://doi.org/10.1016/j.ajodo.2007.01.021.

[3] McNamaraa JA. Maxillary transverse deficiency. Am J Orthod Dentofacial Orthop 2000;117:567-70. https://doi.org/10.1016/S0889-5406(00)70202-2.

[4] Mommaerts MY. Transpalatal distraction as a method of maxillary expansion. Br J Oral Maxillofac Surg 1999;37:268-72. https://doi.org/10.1054/bjom.1999.0127.

[5] Betts NJ, Vanarsdall RL, Barber HD, Higgins-Barber K, Fonseca RJ. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:75-96.

[6] Verstraaten J, Kuijpers-Jagtman AM, Mommaerts MY, Bergé SJ, Nada RM, Schols JGJH, et al. A systematic review of the effects of bone-borne surgical assisted rapid maxillary expansion. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2010;38:166-74.
https://doi.org/10.1016/j.jcms.2009.06.006.

[7] Harzer W, Schneider M, Gedrange T, Tausche E. Direct bone placement of the hyrax fixation screw for surgically assisted rapid palatal expansion (SARPE). J Oral Maxillofac Surg Off J Am Assoc Oral Maxillofac Surg 2006;64:1313-7.
https://doi.org/10.1016/j.joms.2005.11.061.

[8] Williams BJD, Currimbhoy S, Silva A, O'Ryan FS. Complications following surgically assisted rapid palatal expansion: a retrospective cohort study. J Oral Maxillofac Surg Off J Am Assoc Oral Maxillofac Surg 2012;70:2394-402.
https://doi.org/10.1016/j.joms.2011.09.050.

[9] Zandi M, Miresmaeili A, Heidari A. Short-term skeletal and dental changes following bone-borne versus tooth-borne surgically assisted rapid maxillary expansion: A randomized clinical trial study. J Cranio-Maxillofac Surg 2014;42:1190-5. https://doi.org/10.1016/j.jcms.2014.02.007.

[10] Scarfe WC, Farman AG, Sukovic P. Clinical applications of cone-beam computed tomography in dental practice. J Can Dent Assoc 2006;72:75-80.

[11] Bell WH. Le Forte I osteotomy for correction of maxillary deformities. J Oral Surg Am Dent Assoc 1965 1975;33:412-26.

[12] Chane-Fane C, Darqué F. Rapid maxillary expansion assisted by palatal mini-implants in adolescents - preliminary study. Int Orthod 2015;13:96-111.
https://doi.org/10.1016/j.ortho.2014.12.001.

[13] Rungcharassaeng K, Caruso JM, Kan JYK, Kim J, Taylor G. Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion. Am J Orthod Dentofacial Orthop 2007;132:428.e1-428.e8.
https://doi.org/10.1016/j.ajodo.2007.02.052.

[14] Dahlberg G. Statistical methods for medical and biological students. Stat Methods Med Biol Stud 1940.

[15] Kayalar E, Schauseil M, Kuvat SV, Emekli U, Fıratlı S. Comparison of tooth-borne and hybrid devices in surgically assisted rapid maxillary expansion: A randomized clinical cone-beam computed tomography study. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2016;44:285-93.
https://doi.org/10.1016/j.jcms.2015.12.001.
[16] Sygouros A, Motro M, Ugurlu F, Acar A. Surgically assisted rapid maxillary expansion: cone-beam computed tomography evaluation of different surgical techniques and their effects on the maxillary dentoskeletal complex. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2014;146:748-57. https://doi.org/10.1016/j.ajodo.2014.08.013.

[17] Gauthier C, Voyer R, Paquette M, Rompré P, Papadakis A. Periodontal effects of surgically assisted rapid palatal expansion evaluated clinically and with cone-beam computerized tomography: 6-month preliminary results. Am J Orthod Dentofacial Orthop 2011;139:S117-28. https://doi.org/10.1016/j.ajodo.2010.06.022.

[18] van Vlijmen OJC, Bergé SJ, Bronkhorst EM, Swennen GRJ, Katsaros C, Kuijpers-Jagtman AM. A comparison of frontal radiographs obtained from cone beam CT scans and conventional frontal radiographs of human skulls. Int J Oral Maxillofac Surg 2009;38:773-8. https://doi.org/10.1016/j.ijom.2009.02.024.

[19] Camps-Perepérez I, Guijarro-Martínez R, Peiró-Guijarro MA, Hernández-Alfaro F. The value of cone beam computed tomography imaging in surgically assisted rapid palatal expansion: a systematic review of the literature. Int J Oral Maxillofac Surg 2017;46:827-38. https://doi.org/10.1016/j.ijom.2017.01.017.

[20] Laudemann K, Petruchin O, Mack MG, Kopp S, Sader R, Landes CA. Evaluation of surgically assisted rapid maxillary expansion with or without pterygomaxillary disjunction based upon preoperative and post-expansion 3D computed tomography data. Oral Maxillofac Surg 2009;13:159-69. https://doi.org/10.1007/s10006-009-0167-3.

[21] Edel A. Alveolar bone fenestrations and dehiscences in dry Bedouin jaws. J Clin Periodontol 1981;8:491-9. https://doi.org/10.1111/j.1600-051x.1981.tb00898.x.

[22] Romano FL, Sverzut CE, Trivellato AE, Saraiva MCP, Nguyen TT. Alveolar defects before and after surgically assisted rapid palatal expansion (SARPE): a CBCT assessment. Dent Press J Orthod 2022;27:e2219299. https://doi.org/10.1590/2177-6709.27.2.e2219299.oar.

[23] Evangelista K, Vasconcelos K de F, Bumann A, Hirsch E, Nitka M, Silva MAG. Dehiscence and fenestration in patients with Class I and Class II Division 1 malocclusion assessed with cone-beam computed tomography. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2010;138:133.e1-7; discussion 133-135. https://doi.org/10.1016/j.ajodo.2010.02.021.

[24] Enhos S, Uysal T, Yagci A, Veli İ, Ucar FI, Ozer T. Dehiscence and fenestration in patients with different vertical growth patterns assessed with cone-beam computed tomography. Angle Orthod 2012;82:868-74. https://doi.org/10.2319/111211-702.1.

[25] Sun L, Zhang L, Shen G, Wang B, Fang B. Accuracy of cone-beam computed tomography in detecting alveolar bone dehiscences and fenestrations. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2015;147:313-23. https://doi.org/10.1016/j.ajodo.2014.10.032.

[26] van Leeuwen BJ, Dijkstra PU, Dieters JA, Verbeek HPJ, Kuijpers-Jagtman AM, Ren Y. Effect of voxel size in cone-beam computed tomography on surface area measurements of dehiscences and fenestrations in the lower anterior buccal region. Clin Oral Invest 2022. https://doi.org/10.1007/s00784-022-04521-x.

[27] Sondeijker CFW, Lamberts AA, Beckmann SH, Kuitert RB, van Westing K, Persoon S, et al. Development of a clinical practice guideline for orthodontically induced external apical root resorption. Eur J Orthod 2020;42:115-24. https://doi.org/10.1093/ejo/cjz034.
[16] Sygouros A, Motro M, Ugurlu F, Acar A. Surgically assisted rapid maxillary expansion: cone-beam computed tomography evaluation of different surgical techniques and their effects on the maxillary dentoskeletal complex. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2014;146:748-57. https://doi.org/10.1016/j.ajodo.2014.08.013.

[17] Gauthier C, Voyer R, Paquette M, Rompré P, Papadakis A. Periodontal effects of surgically assisted rapid palatal expansion evaluated clinically and with cone-beam computerized tomography: 6-month preliminary results. Am J Orthod Dentofacial Orthop 2011;139:S117-28. https://doi.org/10.1016/j.ajodo.2010.06.022.

[18] van Vlijmen OJC, Bergé SJ, Bronkhorst EM, Swennen GRJ, Katsaros C, Kuijpers-Jagtman AM. A comparison of frontal radiographs obtained from cone beam CT scans and conventional frontal radiographs of human skulls. Int J Oral Maxillofac Surg 2009;38:773-8. https://doi.org/10.1016/j.ijom.2009.02.024.

[19] Camps-Perepérez I, Guijarro-Martínez R, Peiró-Guijarro MA, Hernández-Alfaro F. The value of cone beam computed tomography imaging in surgically assisted rapid palatal expansion: a systematic review of the literature. Int J Oral Maxillofac Surg 2017;46:827-38. https://doi.org/10.1016/j.ijom.2017.01.017.

[20] Laudemann K, Petruchin O, Mack MG, Kopp S, Sader R, Landes CA. Evaluation of surgically assisted rapid maxillary expansion with or without pterygomaxillary disjunction based upon preoperative and post-expansion 3D computed tomography data. Oral Maxillofac Surg 2009;13:159-69. https://doi.org/10.1007/s10006-009-0167-3.

[21] Edel A. Alveolar bone fenestrations and dehiscences in dry Bedouin jaws. J Clin Periodontol 1981;8:491-9. https://doi.org/10.1111/j.1600-051x.1981.tb00898.x.

[22] Romano FL, Sverzut CE, Trivellato AE, Saraiva MCP, Nguyen TT. Alveolar defects before and after surgically assisted rapid palatal expansion (SARPE): a CBCT assessment. Dent Press J Orthod 2022;27:e2219299. https://doi.org/10.1590/2177-6709.27.2.e2219299.oar.

[23] Evangelista K, Vasconcelos K de F, Bumann A, Hirsch E, Nitka M, Silva MAG. Dehiscence and fenestration in patients with Class I and Class II Division 1 malocclusion assessed with cone-beam computed tomography. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2010;138:133.e1-7; discussion 133-135. https://doi.org/10.1016/j.ajodo.2010.02.021.

[24] Enhos S, Uysal T, Yagci A, Veli İ, Ucar FI, Ozer T. Dehiscence and fenestration in patients with different vertical growth patterns assessed with cone-beam computed tomography. Angle Orthod 2012;82:868-74. https://doi.org/10.2319/111211-702.1.

[25] Sun L, Zhang L, Shen G, Wang B, Fang B. Accuracy of cone-beam computed tomography in detecting alveolar bone dehiscences and fenestrations. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2015;147:313-23. https://doi.org/10.1016/j.ajodo.2014.10.032.

[26] van Leeuwen BJ, Dijkstra PU, Dieters JA, Verbeek HPJ, Kuijpers-Jagtman AM, Ren Y. Effect of voxel size in cone-beam computed tomography on surface area measurements of dehiscences and fenestrations in the lower anterior buccal region. Clin Oral Invest 2022. https://doi.org/10.1007/s00784-022-04521-x.

[27] Sondeijker CFW, Lamberts AA, Beckmann SH, Kuitert RB, van Westing K, Persoon S, et al. Development of a clinical practice guideline for orthodontically induced external apical root resorption. Eur J Orthod 2020;42:115-24. https://doi.org/10.1093/ejo/cjz034.
[28] Alqahtani KA, Shaheen E, Morgan N, Shujaat S, Politis C, Jacobs R. Impact of orthognathic surgery on root resorption: A systematic review. J Stomatol Oral Maxillofac Surg 2022;S2468-7855(22)00100-8.
https://doi.org/10.1016/j.jormas.2022.04.010.

[29] Katkar RA, Kummet C, Dawson D, Moreno Uribe L, Allareddy V, Finkelstein M, et al. Comparison of observer reliability of three-dimensional cephalometric landmark identification on subject images from Galileos and i-CAT cone beam CT. Dento Maxillo Facial Radiol 2013;42:20130059.
https://doi.org/10.1259/dmfr.20130059.

[30] Gogna N, Johal AS, Sharma PK. The stability of surgically assisted rapid maxillary expansion (SARME): A systematic review. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2020;48:845-52.
https://doi.org/10.1016/j.jcms.2020.07.003.

[31] Zandi M, Miresmaeili A, Heidari A, Lamei A. The necessity of pterygomaxillary disjunction in surgically assisted rapid maxillary expansion: A short-term, double-blind, historical controlled clinical trial. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2016;44:1181-6.
https://doi.org/10.1016/j.jcms.2016.04.026.

[32] Kilic E, Kilic B, Kurt G, Sakin C, Alkan A. Effects of surgically assisted rapid palatal expansion with and without pterygomaxillary disjunction on dental and skeletal structures: a retrospective review. Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:167-74. https://doi.org/10.1016/j.oooo.2012.02.026.

[33] Perepérez IC, Guijarro-Martínez R, da Rosa BM, Haas OL, Hernández-Alfaro F. Three-dimensional dentoskeletal changes following minimally invasive surgically assisted rapid palatal expansion: a prospective study. Int J Oral Maxillofac Surg 2022;S0901-5027(22)00304-6. https://doi.org/10.1016/j.ijom.2022.07.004.

[34] Karabiber G, Yılmaz HN, Nevzatoğlu Ş, Uğurlu F, Akdoğan T. Three-dimensional evaluation of surgically assisted asymmetric rapid maxillary expansion. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2019;155:620-31.
https://doi.org/10.1016/j.ajodo.2018.05.024.

[35] Muñoz-Pereira ME, Haas-Junior OL, Da Silva Meirelles L, Machado-Fernández A, Guijarro-Martínez R, Hernández-Alfaro F, et al. Stability and surgical complications of tooth-borne and bone-borne appliances in surgical assisted rapid maxillary expansion: a systematic review. Br J Oral Maxillofac Surg 2021;59:e29-47. https://doi.org/10.1016/j.bjoms.2020.08.017.

[36] Carvalho PHA, Moura LB, Trento GS, Holzinger D, Gabrielli M a. C, Gabrielli MFR, et al. Surgically assisted rapid maxillary expansion: a systematic review of complications. Int J Oral Maxillofac Surg 2020;49:325-32.
https://doi.org/10.1016/j.ijom.2019.08.011.
[28] Alqahtani KA, Shaheen E, Morgan N, Shujaat S, Politis C, Jacobs R. Impact of orthognathic surgery on root resorption: A systematic review. J Stomatol Oral Maxillofac Surg 2022;S2468-7855(22)00100-8. https://doi.org/10.1016/j.jormas.2022.04.010.

[29] Katkar RA, Kummet C, Dawson D, Moreno Uribe L, Allareddy V, Finkelstein M, et al. Comparison of observer reliability of three-dimensional cephalometric landmark identification on subject images from Galileos and i-CAT cone beam CT. Dento Maxillo Facial Radiol 2013;42:20130059. https://doi.org/10.1259/dmfr.20130059.

[30] Gogna N, Johal AS, Sharma PK. The stability of surgically assisted rapid maxillary expansion (SARME): A systematic review. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2020;48:845-52. https://doi.org/10.1016/j.jcms.2020.07.003.

[31] Zandi M, Miresmaeili A, Heidari A, Lamei A. The necessity of pterygomaxillary disjunction in surgically assisted rapid maxillary expansion: A short-term, double-blind, historical controlled clinical trial. J Cranio-Maxillo-Fac Surg Off Publ Eur Assoc Cranio-Maxillo-Fac Surg 2016;44:1181-6. https://doi.org/10.1016/j.jcms.2016.04.026.

[32] Kilic E, Kilic B, Kurt G, Sakin C, Alkan A. Effects of surgically assisted rapid palatal expansion with and without pterygomaxillary disjunction on dental and skeletal structures: a retrospective review. Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:167-74. https://doi.org/10.1016/j.oooo.2012.02.026.

[33] Perepérez IC, Guijarro-Martínez R, da Rosa BM, Haas OL, Hernández-Alfaro F. Three-dimensional dentoskeletal changes following minimally invasive surgically assisted rapid palatal expansion: a prospective study. Int J Oral Maxillofac Surg 2022;S0901-5027(22)00304-6. https://doi.org/10.1016/j.ijom.2022.07.004.

[34] Karabiber G, Yılmaz HN, Nevzatoğlu Ş, Uğurlu F, Akdoğan T. Three-dimensional evaluation of surgically assisted asymmetric rapid maxillary expansion. Am J Orthod Dentofac Orthop Off Publ Am Assoc Orthod Its Const Soc Am Board Orthod 2019;155:620-31. https://doi.org/10.1016/j.ajodo.2018.05.024.

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FIGURE LEGEND

Figure 1: Methods for measurement of the radiographic parameters. Orientation of the coronal axis of the axial section perpendicular to the alveolar process (a). Method for measurement of the BT and the BH on a coronal section of P1 and M1 (b). Measurement of the maxillary expansion on a coronal section of the maxillary bone (c). Measurement of the root resorption between the apex and the mesio-vestibular cusp of M1 and the vestibular cusp of P1 (d).

<figure><img src="image_1.png" /></figure>
FIGURE LEGEND

Figure 1: Methods for measurement of the radiographic parameters. Orientation of the coronal axis of the axial section perpendicular to the alveolar process (a). Method for measurement of the BT and the BH on a coronal section of P1 and M1 (b). Measurement of the maxillary expansion on a coronal section of the maxillary bone (c). Measurement of the root resorption between the apex and the mesio-vestibular cusp of M1 and the vestibular cusp of P1 (d).

<figure><img src="image_3.png" /></figure>