"Clinical Evaluation of Root Coverage in Miller Class III Gingival Labial Recessions Treated With Interdisciplinary Periodontic - Orthodontic Therapy: A Randomized Controlled Clinical Trial"

INTRODUCTION Gingival recession is defined as the displacement of the gingival margin apical to the cementoenamel junction with exposure of the root surface to the oral environment.The resulting root surface exposure often causes aesthetic concerns, dentin hypersensitivity and increased susceptibility to root caries.

In 1985, Miller proposed a classification of gingival recession and according to Miller, root coverage is more predictable and more successful with class I and class II defects (upto 100%). However, only partial coverage can be obtained with Miller class III (50-70%) and no coverage can be done in class IV defects (0-10%). Miller class III recession is defined as marginal tissue recession which extends to or beyond the mucogingival junction. There is bone or soft tissue loss interdentally or malpositioning of the tooth.

The two primary etiological factors in the pathogenesis of gingival recession are periodontal diseases and mechanical trauma. Other predisposing factors associated with this condition are labial orthodontic tooth movement, bone dehiscence and fenestration, thin gingival biotype and malpositioning of the teeth.Among the numerous orthodontic treatment procedures and modalities, the proclination of incisors outside their dentoalveolar envelop has been considered as a source of gingival recession for years. It has been assumed that presence of bony dehiscence before the beginning of orthodontic therapy is a prerequisite for the development of gingival recession.However, there are very few clinical studies that have actually investigated the relationship between orthodontic tooth movement and gingival recession. Some of them have shown gingival recession to be associated with proclination of mandibular incisors, whereas others have found no such correlation.

Successful coverage of exposed roots for aesthetic and functional reasons has been the objective of various mucogingival surgeries. Pedicle soft tissue grafts (double-papillae, coronally and laterally positioned flaps), free gingival grafts, subepithelial connective tissue grafts, guided tissue regeneration and acellular dermal matrix allografts combined with coronally positioned flaps are the main surgical techniques that have been used to obtained the root coverage. Certain orthodontic movements such as bodily movements have been found to be effective at improving gingival recession.However, it is necessary to have a sufficient amount of keratinised gingiva for orthodontic movement to contribute to reduction of gingival recession. According to Wennstrom et al., the width of keratinised tissue influences the outcome of root coverage; thick tissues and large amounts of keratinised tissue have a favourable prognosis.Historically, gingival augmentation was done to recreate the zone of attached gingiva. Many still believe that attached gingiva is more suitable to withstand the trauma of mastication and tooth brushing. Huang et al. concluded that the initial gingival thickness is the most decisive factor regarding the accomplishment of complete root coverage.Management of gingival recession in orthodontic patients remains unclear, since no higher level of evidence is available. According to Cortellini et al., there is no information as to whether tooth position (buccal or lingual) might influence the outcome of surgical mucogingival procedures.Esteibar et al. stated that it seems likely that the attainment of complete root coverage in cases traditionally classified as Miller class III and considered less severe would not occur by chance, but rather be a response to some preoperative clinical variables and intraoperative measures.Therefore, an interdisciplinary treatment approach is imperative for some of the challenging and complex dental situations in order to improve aesthetics and prognosis.

Predictable coverage of deep isolated Miller class III anterior gingival recessions is one of the most challenging endeavors in plastic-aesthetic periodontal surgery and limited data is available in the literature. Furthermore, most studies have only evaluated treatment of Miller class I and II isolated mandibular recessions, and limited information is available on the treatment of isolated mandibular Miller class III defects.A thorough search of literature revealed a very modest level of evidence -one study with prospective and retrospective data collection and the other one is a retrospective study. In both of the studies, gingival augmentation surgery was carried out before the orthodontic intervention. It is obvious that a well designed clinical trial needs to be conducted so as to explore this issue. Therefore, the current study has been designed so as to predict how much root coverage could be achieved by interdisciplinary orthodontic and periodontal surgical treatment approach in comparison to periodontal surgical procedure alone in Miller class III gingival recession.