One- Versus Two-Stage Aesthetic Crown Lengthening

Study Overview
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Brief Summary
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This randomized controlled trial was aimed at assessing the efficacy of a two-stage crown lengthening intervention (SCL) for restorative purposes in the aesthetic zone compared with a one-stage crown lengthening procedure (CCL).

Detailed Description
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Subjects were randomly allocated to receive SCL or CCL. SCL consisted of full thickness flaps followed by bone recontouring and minor gingivectomy 4 months postoperatively, if required. In CCL, osseous recontouring after sub-marginal incisions was performed, followed by flap repositioning. Records were obtained at baseline, 4 months (only in SCL), 6 and 12 months. Primary outcome was the precision in achieving a predetermined gingival margin position. Other outcomes were changes in the gingival margin position and keratinized tissue width (KTW) at 12 months, and patient-reported outcomes (PROMs) using the OHIP-14 tool.

Official Title
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One- Versus Two-Stage Aesthetic Crown Lengthening for Restorative Purposes: A Randomized Controlled Trial.

Conditions
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Patients in Need of Surgical CL in the Anterior Maxillary Sextant for Restorative Purposes

Intervention / Treatment
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* Other: Conventional Crown Lengthening (CCL)
* Other: Two-stage Crown Lengthening (SCL)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: older than eighteen years of age; more than 20 teeth in the mouth; with full mouth plaque and bleeding scores lower than 15%; and without probing pocket depth and/or attachment loss >4 mm Exclusion Criteria: Pregnant women or breastfeeding smokers treated with antimicrobial and/or anti-inflammatory drugs within two months prior to entering the study currently undergoing orthodontic therapy

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Conventional Crown Lengthening; CCL<br>Using the surgical guide, submarginal internal bevel incisions were performed on the buccal aspect of the affected teeth. A full-thickness flap was raised up to the mucogingival junction (Dominguez et al., 2020). Ostectomy and osteoplasty were carried out by means of rotatory instruments and surgical chisels, as necessary, to achieve the necessary space between the bone crest and the restorative margin according to the presurgical plan. The CEJ was not the reference point since, in many cases, the position of the final margin of the restoration was planned apical to the actual position of the CEJ. Exposed root surfaces were carefully instrumented manually with curettes and, finally, vertical internal mattress sutures were placed to position the gingival margin at the level of the margin of the planned restoration. Sutures were removed after 7 days. | Other: Conventional Crown Lengthening (CCL)<br>* Using the surgical guide, submarginal internal bevel incisions were performed on the buccal aspect of the affected teeth. A full-thickness flap was raised up to the mucogingival junction (Dominguez et al., 2020). Ostectomy and osteoplasty were carried out by means of rotatory instruments and surgical chisels, as necessary, to achieve the necessary space between the bone crest and the restorative margin according to the presurgical plan. The CEJ was not the reference point since, in many cases, the position of the final margin of the restoration was planned apical to the actual position of the CEJ. Exposed root surfaces were carefully instrumented manually with curettes and, finally, vertical internal mattress sutures were placed to position the gingival margin at the level of the margin of the planned restoration. Sutures were removed after 7 days<br>|
| Experimental: Two-stage Crown Lengthening (SCL)<br>In the first surgical intervention, intrasulcular incisions were performed and a full thickness flap was raised up to the mucogingival junction. Ostectomy and osteoplasty were performed to establish the space for supracrestal tissue attachment, following the restorative plan and using the presurgical blueprint as the reference to determine the final position of the restoration margin, instead of the CEJ (Lee, 2004). Then the flaps were repositioned and secured with internal mattress sutures, placing the gingival margin at the original level. Sutures were removed at 7 days. In the second stage, after 3-4 months, minor gingival recontouring was performed, if necessary, to attain the desired gingival margin position according to the presurgical plan | Other: Two-stage Crown Lengthening (SCL)<br>* In the first surgical intervention, intrasulcular incisions were performed and a full thickness flap was raised up to the mucogingival junction. Ostectomy and osteoplasty were performed to establish the space for supracrestal tissue attachment, following the restorative plan and using the presurgical blueprint as the reference to determine the final position of the restoration margin, instead of the CEJ (Lee, 2004). Then the flaps were repositioned and secured with internal mattress sutures, placing the gingival margin at the original level. Sutures were removed at 7 days. In the second stage, after 3-4 months, minor gingival recontouring was performed, if necessary, to attain the desired gingival margin position according to the presurgical plan.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| T1-T4 | The difference in mm between the ideal gingival margin (T1) and the position of the gingival margin at 12 months (T4). | Baseline-12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Clinical Crown Length | Distance from the gingival margin to the incisal edge on the midbuccal.Measured in mm. | At baseline, 6- and 12-month | 
| Amount of keratinized tissue | Distance from the gingival margin to the mucogingival junction on the midbuccal.Measured in mm. | At baseline, 6- and 12-month | 
| Gingival display upon smiling | Distance from the gingival margin of the central incisors to the lower edge of the upper lip. Measured in mm. | At baseline, 6- and 12-month | 
| Supracrestal tissue dimension | Distance from the gingival margin to the alveolar bone crest (GM-ABC) as determined by bone sounding following local anesthesia. Measured in mm. | At baseline, 6- and 12-month |