Comparison of Vertical Releasing Incisions and Horizontal Extending Incisions for Periodontal Accelerated Osteogenic Orthodontics in the Anterior Region: A Randomized Controlled Trial With Surgical Time, Clinical and Radiographic Outcomes
Phase: NA
Conditions: Malocclusion
Sponsor: Second Affiliated Hospital, School of Medicine, Zhejiang University

Comparison of Vertical Releasing Incisions and
Horizontal Extending Incisions for Periodontal
Accelerated Osteogenic Orthodontics in the
Anterior Region: A Randomized Controlled Trial with
Surgical Time, Clinical and Radiographic Outcomes
ClinicalTrials.gov Identifier: NCT05441683
Document Date: 2020-05-11
Version: 2.0

Protocol and Statistical Analysis Plan
1. Background
In recent years, orthodontic treatment among adult patients has become increasingly
prevalent in clinical practice, accompanied by a rise in orthodontic complications.
Among these, labial bone plate resorption, gingival recession, and root exposure in
the
anterior
region
following
orthodontic
treatment
are
the
most
common
complications and a frequent source of clinical disputes. In 2001, Wilcko et al. [1]
introduced Periodontal Accelerated Osteogenic Orthodontics (PAOO). Initially
developed to accelerate tooth movement during orthodontics [2], this technique has
seen expanded indications and is now primarily utilized to increase alveolar bone
volume and enhance labial bone thickness
[3,4], thereby reducing the risk of
post-orthodontic root exposure. The standard PAOO protocol involves: reflecting a
flap, performing alveolar corticotomy, conducting particulate bone grafting, and
subsequently closing the flap without excessive tension.[5] This technique combines
corticotomy and bone grafting , not only accelerating orthodontic tooth movement but
also augmenting periodontal hard tissue volume, expanding the range of labiolingual
tooth displacement, and mitigating complications such as alveolar bone resorption,
attachment loss, and root exposure.[6]
Due to inherent flap contraction and the increased volume from grafting materials,
conventional PAOO requires periosteal releasing incisions at the flap base and
additional vertical releasing incisions (VRIs) mesiodistally to reduce tension during
flap repositioning.[6] Inadequate tension relief may lead to compromised healing,
including interdental papilla necrosis, gingival recession, root exposure, or graft
exposure with subsequent infection.[7] Beyond tension reduction, VRIs improve
surgical access and simplify the procedure.However, in the esthetically sensitive
anterior region, VRIs often result in visible scarring[8], frequently failing to meet
patients' esthetic expectations. Consequently, some clinicians advocate avoiding VRIs
in anterior periodontal surgeries.[8,9]

Drawing from experience in traditional periodontal soft tissue grafting, we observed
that adequate flap mobilization can be achieved without VRIs. Preliminary PAOO
cases further demonstrated that horizontal extending incisions (HEIs) without VRIs
provided sufficient space for graft placement and achieved favorable healing (Figures
1–2, spanning 1-2 teeth mesiodistally). Notably, during orthodontic movement, bone
resorption predominantly occurs at the cervical region[10], where VRIs offer limited
benefit as grafts tend to migrate apically[11].
Figure 2. Preliminary Case: A: Intraoral photograph at baseline; B: Intraoperative view showing flap
elevation with horizontally extended incisions (1–2 teeth mesiodistally); C: Excellent healing at 2
weeks postoperatively, with no wound dehiscence or graft exposure; D: CBCT comparison
demonstrating significant labial bone augmentation post-treatment.
Figure 1. Schematic diagram of two different releasing incisions for periodontal accelerated
osteogenesis orthodontics (PAOO) surgery: Vertical relaxation incisions (VRI) were made bilaterally on
the distal side of the first premolar; Horizontal extension incisions (HEI) were added one more tooth on
each side, extending to the distal of the second premolar.

2. Aim
Currently,
the
comparative
effects
of
VRIs
versus
HEIs
on
PAOO
outcomes—including surgical efficiency, healing kinetics, adverse events, and bone
augmentation efficacy—remain unclear, leaving the choice to individual operator
preference. This randomized controlled trial evaluates both incision designs in
anterior PAOO, comparing operative time, wound healing, complications, and bone
gain to establish evidence-based surgical guidelines.
3. Study Design and Methods
This is a single-center, simply randomized, parallel-group clinical trial with 1:1
allocation ratio. The study will be conducted at the Department of Periodontology,
Second Affiliated Hospital of Zhejiang University School of Medicine from ethics
approval date 2022 through June 2024.
3.1 Inclusion Criteria:
(1) Patients aged 18-40 years without systemic diseases who are undergoing or
planning orthodontic treatment
(2) Patients with thin alveolar bone and/or fenestration/dehiscence of labial bone
plates in anterior teeth
(3) Patients whose anticipated orthodontic tooth movement will exceed the labial
alveolar bone boundaries
3.2 Exclusion Criteria:
(1) Current smokers
(2) Pregnancy or lactation
(3) Untreated periodontitis
(4) Insufficient keratinized gingiva width (<2mm) or thin periodontal biotype
(assessed by probing) [12]
(5) History of orthodontic and/or orthognathic treatment
(6) Systemic diseases contraindicating surgery (diabetes, hypertension, cardiac

diseases, malignancies, severe psychiatric disorders, etc.)
(7) Long-term use of immunosuppressants, bisphosphonates, or other relevant
medications
(8) Poor compliance (unable to complete 1-year follow-up)
3.3 Withdrawal Criteria
(1) Development of exclusion criterion-related conditions requiring intervention
(2) Loss to follow-up during study period (excluding migration/death)
3.4 Ethical Considerations
This study will recruit orthodontic patients (either currently undergoing treatment or
scheduled to begin treatment) from the Department of Orthodontics at the Second
Affiliated Hospital of Zhejiang University School of Medicine. After being assessed
by investigators and meeting the inclusion criteria, eligible participants will be
referred to the Department of Periodontology where researchers will explain the
clinical trial in detail and review the informed consent documents. All enrolled
participants must provide written informed consent before participation. This study
explicitly excludes vulnerable populations including individuals with mental disorders,
critically ill patients, pregnant women, illiterate persons, minors (<18 years old),
cognitively impaired individuals, students of principal investigators or research staff,
subordinates of principal investigators or collaborating investigators, and employees
of the research institution or study sponsor. The study protocol has been reviewed and
approved by the Institutional Review Board/Ethics Committee of the Second
Affiliated Hospital of Zhejiang University School of Medicine.
3.5 Preoperative Preparation:
Enrolled patients will complete cone beam computed tomography (CBCT) and
routine tests (complete blood count, coagulation profile, and four infectious disease
markers). Researchers will provide oral hygiene education and perform supragingival
ultrasonic scaling before scheduling the surgery.
On the surgery day, Researcher J will conduct preoperative baseline measurements

including: probing depth (PD), clinical attachment level (CAL), keratinized gingival
width (KGW), gingival recession depth (GRD), and gingival thickness. Preoperative
CBCT measurements will include alveolar vertical height and alveolar ridge
horizontal width (measured below the cemento-enamel junction at 2mm, 4mm and
6mm, recorded as BW2, BW4 and BW6 respectively). The bone graft material will be
weighed with its container before surgery (recorded as W0+1) and the container will
be weighed after surgery (W0). The net weight of graft material before surgery is
recorded as W1 (W1=W0+1-W0). The remaining bone graft material will be collected
after surgery, dried and weighed (recorded as W2). The actual amount of bone graft
material used during surgery ( Δ W) equals W1-W2. All measurements will be
performed in duplicate and averaged. Prior to actual measurements, the researchers
have passed consistency testing with Kappa value >0.4.
3.6 Surgical procedures:
The surgical duration will be timed from initial gingival incision (post-anesthesia) to
final suture placement, with measurements recorded by an external observer receiving
signals from the circulating nurse.
A sulcular incision will be made on the labial aspect of anterior teeth. For the
experimental group, horizontally extended incisions spanning 1-2 teeth will be added
bilaterally to the sulcular incision, while the control group will receive vertical
releasing incisions bilaterally. A full-thickness flap will be elevated extending 5mm
beyond the root apex. Linear corticotomies parallel to the root axis will be created
using piezoelectric surgery to access the medullary cavity. Geistlich Bio-Oss®
(Switzerland) bone graft material will be placed on the alveolar bone surface and
covered with a resorbable collagen membrane. A partial-thickness flap will be
elevated at the apical region to achieve tension-free flap closure and suturing.
Postoperative instructions will be provided by the researchers, along with follow-up
appointment scheduling.
3.7 Postoperative Follow-up:

Weeks 1 and 2: Assess facial swelling, pain, mucosal color, edema, and membrane
exposure. Sutures removed at 2 weeks.
Months 3, 6 and 12 (CBCT evaluations at 6 and 12 months): recording PD, CAL,
KGW, GRD, scar formation, and alveolar dimensions.
3.8 Sample Size Calculation:
Based on the study by Zucchelli et al. [8], in the treatment of multiple-tooth gingival
recession with coronally advanced flaps, the addition of vertical releasing incisions
showed no significant effect on PD, CAL, GRD, or KTH changes at 12 months
postoperatively. However, the group with vertical releasing incisions required
significantly longer operative time (34.6 ± 3.9 min) compared to the group without
(28.7 ± 2.2 min; P < 0.01). Using these data as reference, this study adopted an

independent samples t-test model with the following parameters: significance level (α)
= 0.05 (two-tailed), power (1 - β) = 0.95, allocation ratio = 1:1. The required sample
size was calculated using G*Power 3.1 software, yielding 9 patients per group. To
account for a potential 20% dropout rate, the final sample size was adjusted to 11
patients per group (total N = 22).
3.9 Data Management and Confidentiality
A simple randomization method was employed: generated a list of 22 IDs (1-22) in
Excel 2013, created a corresponding column of random numbers (0-1) and sorted IDs
accordingly, first 11 IDs assigned to the test group (PAOO with horizontal extending
incisions), remaining 11 IDs assigned to the control group (PAOO with vertical
releasing incisions). Researcher A prepared sealed, opaque envelopes labeled with
IDs 1-11, each containing a card specifying the assigned surgical approach. After
sealing, Researcher A handed the envelopes to Researcher B and withdrew from
further involvement. Researcher B enrolled participants based on inclusion criteria,
assigned IDs sequentially by enrollment order, delivered sealed envelopes to the
surgeon (W) intraoperatively, and conducted all postoperative measurements. All data
underwent dual entry with third-party verification. Access required approval from the
principal investigator. All identifiable records were kept confidential and disclosed
only as legally permitted.
3.10 Statistical methods
Statistical analysis was performed using SPSS software (IBM Corp., Armonk, NY).
Categorical
variables
were
expressed
as
frequencies
and
percentages,
with
comparisons between groups using the Chi-square test or Fisher's exact test.
Quantitative data including periodontal and radiographic measurements were
expressed as mean, standard deviation (SD), median, and interquartile range (IQR).
Intergroup
comparisons
utilized
independent
t-tests
(normal
distribution)
or
Mann-Whitney U tests (non-normal). The median differences and 95% confidence
intervals (CIs) for the skewed data were estimated using the Hodges-Lehmann

method. Changes over time were evaluated using paired t-tests or Wilcoxon
signed-rank tests. All tests were conducted with a two-tailed hypothesis, and
statistical significance was set at set at P < 0.05. Measurement reliability was
confirmed by intraclass correlation coefficient (ICC) from duplicate assessments (40
sites, 2-week interval) by a single examiner.
4. Informed Consent
This trial excluded vulnerable populations. Written informed consent was mandatory
prior to study procedures, with details provided in the consent form. The consent
process included: orthodontic patients at the study center were screened for PAOO
eligibility by researchers; eligible candidates were referred to the Periodontology
Department, where the study team explained the trial's risks/benefits in lay terms;
after ensuring comprehension, participants voluntarily signed the consent form to
proceed. Throughout the study (preoperative to follow-up), researchers addressed
participant queries promptly.
5. Adverse Event Reporting
Participants in this study may face risks associated with periodontal surgery, with
prevention, management and reporting procedures being identical to standard clinical
protocols for periodontal surgical adverse events. Should any discomfort, new
symptoms, or unexpected incidents occur during the study period - regardless of
perceived relation to the research - the attending physician will evaluate and provide
appropriate
medical
intervention.
The
following
reporting
protocols
will
be
implemented for adverse events:
•All Adverse Events (AEs): Immediate management measures will be taken and
properly documented in the case report forms.
•Serious Adverse Events (SAEs): In addition to immediate management and
documentation in case report forms, the investigator will determine whether to
discontinue or adjust treatment. SAEs must be immediately reported to:the Ethics
Committee, Clinical Trial Institution, Study Sponsor and National and Provincial

Food and Drug Administration (within 24 hours). All SAEs must be additionally
reported through the hospital's "Non-Punitive Internal Reporting System for Adverse
Events and Near Misses".
References
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Full-thickness flap/subepithelial connective tissue grafting with intramarrow penetrations: three case
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[2] Kamal AT, Malik DES, Fida M, Sukhia RH. Does periodontally accelerated osteogenic
orthodontics improve orthodontic treatment outcome? A systematic review and meta-analysis.
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[3] Mandelaris GA, Richman C, Kao RT. Surgical Considerations and Decision Making in Surgically
Facilitated Orthodontic Treatment/Periodontally Accelerated Osteogenic Orthodontics. ClinAdv
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10.3390/ma14226967.
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