Nutrient canals and porosity of the bony palate: A basis for the biological plausibility of the anterior middle superior alveolar nerve block.

BACKGROUND: The authors investigated morphologic parameters of the palatal cortex that affect the diffusion of local anesthetic solution in the region of the anterior middle superior alveolar (AMSA) nerve block injection site.

METHODS: The authors used computed tomographic (CT) and micro-CT imaging to assess 20 human skulls from an anatomic collection. Analysis of the CT images included frequency, distribution, and width of the nutrient canals in the bony palate, according to to the person's sex and age. Micro-CT analysis involved measuring the thickness and porosity of palatal cortical bone in the area of the AMSA injection site in relation to the thickness and porosity of the opposite buccal cortical bone.

RESULTS: There was a statistically significant difference (P = .042) in the location of the nutrient canals between male specimens (> 50% in the border region) and female specimens (> 50% in the palatal process). Furthermore, the female skulls had significantly wider nutrient canal foramina (P = .042) than did the male skulls. Despite greater thickness, the palatal cortex in the area of the AMSA injection site had slightly greater porosity than did the buccal cortex. A significantly greater number of microcanals penetrated the whole cortical thickness in palatal than in buccal cortical bone (P = .001).

CONCLUSIONS: The distribution and width of nutrient canals differed between male and female skulls. At the microscopic level, structural characteristics of the palatal cortex provide a good anatomic basis for the potential of a satisfactory AMSA injection success rate.

PRACTICAL IMPLICATIONS: The AMSA technique success rate might be increased if the clinician adjusts the injection site to the distribution of nutrient canals, depending on the sex of the patient.