Correlations of gingival biotype with clinical crown and periodontal parameters in maxillary and mandibular jaws

The gingival biotype (GB) influences treatment planning and clinical outcomes in several dental specialties. This study aimed to investigate the associations between the GB and various clinical crown and periodontal parameters, such as probing depth (PD), papillary height (PH), keratinized tissue width (KTW), crown width/crown length ratio (CW/CL), and gingival thickness (GT). The secondary objective was to evaluate the optimal cutoff values for all parameters to determine the GB in both the maxillary and mandibular anterior teeth.

This cross-sectional study included 50 healthy individuals (26 men and 24 women) aged between 20 and 35 years. The GB was determined as a binary variable based on the transparency of a periodontal probe through the buccal gingival margin (TRAN). The clinical crown and periodontal parameters, such as PH, PD, KTW, GT (free gingival thickness [FGT] and attached gingival thickness [AGT]), and the CW/CL ratio were measured. The associations between different variables were evaluated by the chi-square test. Correlations between various clinical parameters and GB were assessed using point-biserial correlation analyses. Receiver operating characteristic (ROC) analysis and the Youden index were used to calculate the optimal cutoff values for the PH, PD, KTW, FGT, AGT, and CW/CL ratio to discriminate GB. The statistical significance level was set at p < 0.05.

The mean age of the males was 28.23 ± 2.81 years, while that of the females was 27.08 ± 2.85 years. Thick GB was present in 56% of individuals, and thin GB was present in 44% of individuals. Compared with females, males had a predilection for thick GB compared with females. According to the ROC analysis, the cutoff values to discriminate GB for mandibular anterior teeth were 3.4 mm for PH, 1.96 mm for PD, 4.21 mm for KTW, 0.98 mm for FGT, 0.43 mm for AGT, and 0.91 for the CW/CL ratio. Similarly, the cutoff values for discriminating the GB for maxillary anterior teeth were 4.02 mm for PH, 1.92 mm for PD, 3.89 mm for KTW, 1.02 mm for FGT, 0.42 mm for AGT, and 0.83 for the CW/CL ratio. PH, PD, and FGT showed strong positive correlations with GB, whereas KTW, AGT, and the CW/CL ratio showed weak positive correlation with GB.

Within the limitations of the present study, a significant association between all clinical crown and periodontal parameters with the GB has been confirmed. FGT for mandibular anterior teeth and PH for the mandibular anterior teeth have emerged as the most reliable measurements to differentiate between thick and thin GB based on ROC analysis.

All the clinical parameters such as papillary height, probing depth, width of keratinized gingiva, gingival thickness, and crown width/height ratio were significantly associated with gingival biotype. Free gingival thickness for mandibular anterior teeth and papillary height for the maxillary anterior teeth have emerged as the most reliable measurement to differentiate between thick and thin gingival biotypes.