IADR Abstract Archives
Anatomical Assessment of Mandibular Buccal Shelf for Miniscrew Insertion
Objectives: The objective of this study was to anatomically assess the mandibular buccal shelf as insertion site for orthodontic mini implants by investigating the cortical bone thickness and the bone depth.
Methods: Buccal-lingual bone width was assessed at 3 different possible insertion sites at the buccal shelf on CBCT scans of 30 caucasian patients (18 female and 12 male, mean age 14.5 ± 2 years). Two dimensional slices bisecting the sites of interest were generated and cortical bone thickness was measured adjacent to distal root of first molar, mesial and distal roots of the second molar. Bone depth was measured at same sites at 4 and 8 mm from CEJ. STL models of patients were superimposed on the CBCT volumes to virtually create an outline of the soft tissue on the CBCT image to allow identification of the purchase point height (muco-gingival junction). The inferior alveolar nerve was digitally traced. Miniscrews (1.6 x 10 mm) were virtually placed at the buccal shelf and their insertion depth and relationship to the nerve were assessed.
Results: Insertion sites and measurement level had a significant impact on both cortical bone thickness and bone depth. Cortical bone thickness was typically greatest at the distal root of second molar. Bone depth was greatest at the distal surface of second molar 8mm from CEJ. The greatest bone insertion depth was found disto-buccal to the second molar, while the mini implants had greatest proximity to the nerve at this site also.
Conclusions:
The disto-buccal cusp level of the mandibular 2nd molar is the most appropriate site for miniscrew insertion at the buccal shelf.
Methods: Buccal-lingual bone width was assessed at 3 different possible insertion sites at the buccal shelf on CBCT scans of 30 caucasian patients (18 female and 12 male, mean age 14.5 ± 2 years). Two dimensional slices bisecting the sites of interest were generated and cortical bone thickness was measured adjacent to distal root of first molar, mesial and distal roots of the second molar. Bone depth was measured at same sites at 4 and 8 mm from CEJ. STL models of patients were superimposed on the CBCT volumes to virtually create an outline of the soft tissue on the CBCT image to allow identification of the purchase point height (muco-gingival junction). The inferior alveolar nerve was digitally traced. Miniscrews (1.6 x 10 mm) were virtually placed at the buccal shelf and their insertion depth and relationship to the nerve were assessed.
Results: Insertion sites and measurement level had a significant impact on both cortical bone thickness and bone depth. Cortical bone thickness was typically greatest at the distal root of second molar. Bone depth was greatest at the distal surface of second molar 8mm from CEJ. The greatest bone insertion depth was found disto-buccal to the second molar, while the mini implants had greatest proximity to the nerve at this site also.
Conclusions:
The disto-buccal cusp level of the mandibular 2nd molar is the most appropriate site for miniscrew insertion at the buccal shelf.