Prevalence of the Gingival Phenotype in Adults and Associated Risk Factors: A Systematic Review of the Literature

The relevance of assessing the gingival phenotype prior to the initiation of periodontal, orthodontic, or prosthetic therapy has been clearly demonstrated. However, publications on this subject are either old or concerned with the means of assessing the gingival phenotype or the main factors likely to modify it. The main objective of this systematic review of the literature was therefore to investigate the prevalence of different gingival phenotypes in adults in good general health and with a healthy periodontium. A systematic review of the literature was performed following the guidelines of PRISMA recommendations using an electronic search strategy on four databases (PubMed, Scopus, Cochrane Library, and Embase) complemented by a manual search. Three independent authors were involved in study selection, data extraction, and bias assessment. Results: Of 807 articles, 17 of them, published between 2012 and 2023, involving 3277 subjects from 11 countries and 9766 dental sites, fulfilled the inclusion criteria. The prevalence of the gingival phenotype could not be determined at the level of an individual or a dental arch because all the publications assessed this phenotype only at the level of certain dental sectors, and were not chosen at random. The maxillary central incisors and maxillary or mandibular first molar sectors were associated with a high and thick gingival phenotype, independently of the dental morphology, gender, and age of adult subjects. Furthermore, in these regions, this gingival phenotype tended to be associated with a thick vestibular bone table. In contrast, maxillary and mandibular incisors and premolars more often had a thin gingival phenotype. For other teeth, the results were less conclusive. It is important not to rely solely on the overall appearance of the dentition but to independently assess the thickness and height of the gingiva at each dental site requiring intervention. Finally, this study highlights a key point, namely the need for further longitudinal studies to determine the prevalence in healthy adults. For practicality and feasibility reasons, these studies should be designed according to therapeutic needs, dental sector by dental sector, and within homogeneous source populations. PROSPERO registration: CRD 42023392602.