Relationship between smile type and periodontal phenotype: A clinical and tomographic cross-sectional study

To evaluate the correlation between smile type (ST) and the periodontal phenotype (PP).

Clinical and photographic examinations of 164 participants (48 men and 116 women, mean age 22.9 ± 4.6 years) were performed, including an evaluation of ST (high, average, and low), gingival phenotype (GP) by transparency of the periodontal probe (TRAN), keratinized tissue width (KTW), gingival architecture (GA), tooth shape (TS), and papilla height (PH). A subgroup of 70 participants underwent soft-tissue cone-beam tomographic examinations (ST-CBCT), in which GP, gingival thickness (GT), buccal bone thickness (BBT), and the distances from the gingival margin and cementoenamel junction to the buccal bone crest (GM-BBC and CEJ-BBC) were evaluated. The data were analyzed using one-way ANOVA, Student's t-test, and chi-square tests, with the level of significance set at 0.05.

High, average, and low STs were found in 31.7%, 56.7%, and 11.6% of the participants, respectively. Sex (p=0.001), GP evaluated using TRAN (p=0.021) and ST-CBCT scans (p=0.009), GA (p<0.001), and TS (p=0.001), were associated with STs. The prevalence of thin GP was: 63% in low, 50% in average, and 38% in high smile types. KTW (p=0.004), PH (p<0.001), GT at different landmarks (p<0.05), CEJ-BBC (p=0.017), and GM-BBC (p=0.001) were significantly different among STs. The highest GT and KTW were found in the high-smile group, average-smile presented the higher CEJ-BBC while GM-BBC and PH, were higher in low-smile group.

Periodontal phenotype components presented important difference over the smile types.

A detailed examination of smile types is an essential part of treatment planning, especially when the patient has high esthetic demands. Clinical and tomographic individual analysis of periodontal phenotypes over the smile types may be helpful for a case-by-case approach, and for the development of well-defined treatment protocols.