Virtual Placement of The Mandibular Buccal Shelf Bone Screw: A CBCT Evaluation

• Author Details:   
• Minu C Mathews ^*
• Bejoy P.U

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Background & objectives: Buccal shelf area of mandible is a recent addition to temporary anchorage device. The purpose of this study for the assessment of mandibular buccal shelf area for miniscrew insertion using CBCT.
Methods: 24 CBCT images were collected and analysed using ONDEMAND software. Mini screws of 2 x 10 mm, 2 x 12 mm were customised digitally in the software and virtually placed it in particular angles and positions. 4 areas considered are Buccal to the distobuccal cusp of first molar (P1), Buccal to the Interdental area of first and second molar (P2), Buccal to mesiobuccal cusp of second molar (P3), Buccal to distobuccal cusp of second molar (P4). Miniscews are inserted in 00 (A1), 200 (A2), 300 (A3) angulation to the vertical axis of the tooth and 4mm (H1) and 6mm (H2) apical to cemento Enamel Junction of first and second molar. The cortical bone
thickness, the distance from molar root and distance from digitally traced inferior alveolar nerve were measured.
Statistical analyses were performed using Statistical Package for Social Sciences software (SPSS version 26, USA). Normality was checked using the Shapiro Wilk test. As data were not normal Kruskal Wallis ANOVA test was used to compare the data between groups. Bonferroni post hoc tests were used to find out pairwise comparisons. A p-value of <0> Results and discussion: Cortical bone thickness increases as it moves distally from the first
molar to the second molar. As insertion depth increases both cortical bone thickness and root
clearance become greater. The implant can be placed parallel to the long axis of the tooth
adjacent to it as it gives more cortical bone engagement and enough clearance from the root.
There is sufficient clearance from the mandibular nerve in all sites and depth at all angulation, so
implant insertion is safe at MBS. Root proximity is a limiting factor as there is no enough
clearance for root at many sites. Mesiobuccal area of second molar is considered as safe place
for insertion of miniscrew.

Conclusion: The suitable site for miniscrew insertion for the south Indian population, considered as buccal to the mesiobuccal area of the second molar at 6mm from CEJ and parallel to the long axis of the buccal cusp of the second molar and the implant size is 2x10mm or less.

Keywords: Mandibular buccal shelf; Miniscrew; Cortical bone thickness; CBCT.