Relationships between periodontal biotype and anatomical bone features of placement sites for orthodontic anchoring screw: a cross-sectional study

Objectives: This study investigated relationships between bone thickness at the insertion sites of orthodontic anchoring screws (OASs) and periodontal biotype (PB) using cephalograms and cone-beam computer tomography (CBCT). Materials and methods: The PB at the maxillary central incisors was evaluated to differentiate into three categories. In total, 71 patients were examined to determine the relationship between PB and palatal bone thickness using cephalograms. Of these, 57 patients with CBCT were investigated further to explore the relationship between PB and bone thickness at the palatal and buccal regions. Mann-Whitney U-test and t-test were performed for comparisons in each PB group. Results: The thickness of the palatal bone (p = 0.010) and cortex (p = 0.006) in patients with thick biotype in posteroanterior (PA) cephalograms was significantly greater than that those with thin biotype. CBCT evaluations showed that the paramedian bone thickness in the section between premolars in thick biotype (8.38 ± 2.61 mm) was significantly greater than that in thin biotype (6.41 ± 2.95 mm, p = 0.000). Regarding the buccal alveolar area, the cortical bone thickness in thick biotype was greater than those in medium and thin biotypes (p < 0.0167). Conclusions: Thick biotype had thicker paramedian bones and palatal cortexes than with thin biotype in PA cephalograms. From CBCT images, the paramedian bone thickness in the section between premolars significantly differed according to PB. Cortical bone thickness in the buccal area from the first premolar to the second molar in the maxilla demonstrated statistically significant differences among PBs. Clinical relevance: PB is a potentially useful preoperative screening test for OAS placement.