Received: 2 June 2020 | Revised: 11 August 2020 | Accepted: 22 September 2020 DOI: 10.1111/jcpe.13375 ORIGINAL ARTICLE CLINICAL PERIODONTOLOGY One- versus two-stage crown lengthening surgical procedure for aesthetic restorative purposes: A randomized controlled trial Oscar González-Martín1,2 | Georgina Carbajo1,2 | Marta Rodrigo1,2 | Eduardo Montero1,2,3 | Mariano Sanz1,3 1Faculty of Odontology, University Complutense of Madrid, Madrid, Spain Abstract 2Private Specialist Practice, Madrid, Spain Aim: This randomized controlled trial aimed to assess the efficacy of a two-stage 3 ETEP (Etiology and Therapy of crown lengthening intervention (SCL) in the aesthetic zone compared with a one- Periodontal and Peri-implant Diseases) Research Group, Faculty of Odontology, stage crown lengthening procedure (CCL). University Complutense of Madrid, Materials and methods: Thirty subjects were randomly assigned to either SCL (n = 15) Madrid, Spain or CCL (n = 15) groups. SCL consisted of full-thickness flaps followed by bone recon- Correspondence touring and gingivectomy 4 months postoperatively, if required. In CCL, osseous re- Oscar González-Martín, Private Practice Gonzalez + Solano Atelier Dental, c/Blanca contouring after submarginal incisions was performed, followed by flap repositioning. de Navarra 10, Bajo, 28010 Madrid, Spain. Records were obtained at baseline, 4 months (only in SCL), 6 months and 12 months. Email: [email protected] Primary outcome was the precision in achieving a pre-determined gingival margin position. Other outcomes considered were changes in the gingival margin position and keratinized tissue width (KTW) at 12 months, and patient-reported outcomes (PROMs). Results: Surgical precision was comparable between groups (0.2 ± 0.4 mm in the CCL group and −0.2 ± 0.5 mm in the SCL group). Four patients in the SCL group (27.7%) did not require a second-stage surgery. KTW was significantly higher in the SCL group (6.3 ± 1.4 mm versus 5.0 ± 1.4 mm, p = 0.017). SCL resulted in a lower impact on qual- ity of life when compared to the CCL group. Conclusions: Both approaches were highly accurate obtaining the desired crown length. SCL was associated with a lower reduction in KTW and more favourable oral health-related quality of life (OHIP-14). KEYWORDS aesthetic crown lengthening, crown lengthening, periodontal surgery, randomized clinical trial Trial registration: ClinicalTrials.gov Registration Number NCT04409366. © 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd J Clin Periodontol. 2020;00:1–11. wileyonlinelibrary.com/journal/jcpe | 1 2 | GONZÁLEZ-MARTÍN et al. 1 | INTRODUCTION Clinical Relevance Crown lengthening (CL) is a surgical procedure used to either fa- Scientific rationale for the study: Little is known regarding cilitate restorative dentistry or improve patient's aesthetic demands the efficacy of different aesthetic crown lengthening sur- when there is excessive gingival exposure during smile or when gin- gical interventions. gival enlargement prevents from adequate oral hygiene practices Principal findings: Both crown lengthening surgical ap- (Lee, 2004). In fact, crown lengthening surgical procedures have proaches (one- versus two-stage) demonstrated com- been estimated to represent approximately 10% of all periodontal parable clinical outcomes. However, patients receiving surgical procedures (AAP, 2004). the two-stage intervention reported a lower impact on Depending on their main objective, CL surgical interventions their quality of life. Additionally, a wider band of KTW have been categorized as aesthetic or functional, depending on if was observed in the group that received the two-stage they aim to improve aesthetic outcomes in situations of excessive intervention. gingival display and/or altered passive eruption, or for restorative Practical implications: Two-stage aesthetic crown length- purposes, in situations where subgingival caries or fractures require ening not only resulted in similar clinical outcomes when the exposure of subcrestal sound tooth structure. However, both compared with conventional (one-stage) crown lengthen- have in common the objective of the re-establishment of the supra- ing approach, but also had a higher acceptance by patients. crestal tissue attachment, since it is well known that the impinge- ment of this space, either with restoration margins or with apically positioned flaps, may result in bone resorption, gingival recession, chronic inflammation or gingival hypertrophy (Jepsen et al., 2018). recession. To overcome some of these limitations, an alternative CL Furthermore, functional and aesthetic objectives may converge in surgical approach in two stages was proposed (Sonick, 1997). This the restorative treatment of the anterior maxilla when the balance surgical approach involves two-staged surgical interventions. In the between the so-called pink and white aesthetics is not adequate. In first surgical phase, after raising a full-thickness flap following in- CL surgical interventions aimed to satisfy high aesthetic demands, tra-sulcular incisions, the space for supracrestal tissue attachment it is imperative to achieve an ideal position of the gingival margins is re-created by ostectomy and osteoplasty by direct visualization (Herrero et al., 1995) and maintain this position long term (Deas of the CEJ anatomy, and then the flap is re-positioned and sutured. et al., 2014). This outcome, however, is not always predictable, since Three to four months later, once the supracrestal tissue attachment factors such as the position of the gingival margin relative to the is re-established, a second minimally invasive surgical intervention bone crest (Deas et al., 2014; Lanning et al., 2003), the extent of is carried out, if needed, by only minor gingival recontouring to at- ostectomy performed (Deas et al., 2004), the patient's periodontal tain the ideal gingival margin contours. This approach is expected phenotype, the healing time (Pontoriero & Carnevale, 2001) and to reduce the risk associated with the initial removal of soft tissue the experience of the surgeon (Herrero et al., 1995) may influence based on anatomical landmarks that may be difficult to determine the result. A recent systematic review has evaluated the evidence with precision, such as the CEJ or the bone crest. Unfortunately, de- of CL performed for restorative reasons (Pilalas et al., 2016), iden- spite the claimed therapeutic advantages and theoretical improved tifying 4 non-randomized and 1 randomized controlled clinical trial. treatment outcomes, the efficacy of the two-stage intervention has These studies, however, were considered as high risk of bias, and not been assessed properly in controlled studies. It was, therefore, no study had more than 6-month follow-up or stated unequivocally the aim of this randomized clinical trial to assess the efficacy of a whether the postoperative outcome was adequate for the intended two-stage surgical crown lengthening procedure (SCL) compared restorative purposes. Furthermore, they did not identify any trial with the standard one-stage (CCL) intervention in clinical situations comparing surgical techniques. Therefore, there is minimal evidence where the objective of the CL procedure was aimed for aesthetic regarding the efficacy of these surgical interventions. restorative purposes. Conventional crown lengthening procedures are typically ac- complished by apically positioned flap (APF) with/without osseous resection (Palomo & Kopczyk, 1978). They are usually carried out 2 | MATERIALS AND METHODS as a one-stage procedure in which submarginal scalloped incisions and full-thickness flaps are followed by bone recontouring to re-cre- 2.1 | Study design ate the space for adequate supracrestal tissue attachment. Incision design and the amount of bone recontouring are usually guided by This study was designed as a parallel-arm, single-centre, randomized the pre-surgical assessment of the CEJ either through transgin- controlled clinical trial (RCT) with a 12-month follow-up. The study gival probing or by radiographic examination. However, this infor- protocol was approved by the institutional ethic committee (Internal mation may not be accurate (Christiaens et al., 2018) and result in Code 11/057-E, Hospital Clínico de San Carlos, Madrid) and regis- unfavourable outcomes, such as marginal tissue rebound or gingival tered at ClinicalTrials.gov (NCT04409366). GONZÁLEZ-MARTÍN et al. | 3 FIGURE 1 CONSORT flow chart 4 | GONZÁLEZ-MARTÍN et al. 2.2 | Patient population 2.4.2 | Conventional Crown Lengthening; CCL Patients were recruited in the Postgraduate Clinic of Periodontology Using the surgical guide, submarginal internal bevel incisions were at the University Complutense in Madrid (Spain), from among those performed on the buccal aspect of the affected teeth. A full-thick- in need of surgical CL in the anterior maxillary sextant for aesthetic ness flap was raised up to the mucogingival junction (Dominguez restorative purposes, if they fulfilled the following criteria: et al., 2020). Ostectomy and osteoplasty were carried out by means of rotatory instruments and surgical chisels, as necessary, to achieve 1. older than eighteen years of age; the necessary space between the bone crest and the restorative 2. more than 20 teeth in the mouth; margin according to the pre-surgical plan. The CEJ was not the ref- 3. with full-mouth plaque and bleeding scores lower than 15%; and erence point since, in many cases, the position of the final margin of 4. without probing