Facial, dental, periodontal, and tomographic characteristics of the etiology of excessive gingival display: a cross-sectional clinical study.

Purpose: In this study, we examined the facial, dental, periodontal, and tomographic features associated with excessive gingival display (EGD) when smiling in young adults self-reporting a "gummy smile," categorized by potential etiology.

Methods: The study included 25 healthy adults (18-42 years old; 23 women and 2 men) who self-reported EGD. Participants completed a health questionnaire and underwent a periodontal examination assessing probing depth, clinical attachment level, keratinized gingival width, and gingival thickness (GT). Extraoral and intraoral photographs were taken for smile analysis and to determine facial and dental characteristics. Cone-beam computed tomography (CBCT), performed with a lip retractor in place, was used to measure the distance from the gingival margin (GM) to the cementoenamel junction (CEJ), the distance from the CEJ to the alveolar crest, buccal bone thickness, and GT. The extent of EGD when smiling was quantified as the distance from the GM at the upper central incisor to the upper lip edge when smiling fully. The smile was categorized into 4 types based on gingival exposure characteristics observed during full smile.

Results: Most participants were female (92%), with a mean age of 28.77±6.56 years. The average EGD was 4.2±2.44 mm, extending bilaterally from the anterior to the posterior maxilla. Two primary etiological factors were identified, alone or in combination: vertical maxillary excess (VME), predominantly indicated by an anterior maxillary height greater than 29 mm and a large interlabial gap; and altered passive/active eruption (APE), primarily characterized by square teeth (64%), upper central incisor width-to-height ratio (CIW:CIH) exceeding 87.5%, and GM-CEJ distance on CBCT exceeding 2 mm.

Conclusions: These findings suggest a multifactorial etiology of EGD, primarily associated with VME and APE. Clinical periodontal examination, CBCT conducted with a lip retractor, CIW:CIH, and soft tissue facial cephalometric analysis may aid in identifying the etiological factors of EGD.