Maxillary Soft Tissue and Cortical Bone Thickness for Mini-implant Placement

The midpalatal suture area and maxillary interdental area are suitable site for the placement of orthodontic mini-implant. The purpose of this study was to provide a guideline to indicate the best location for mini-implant placement as it relates to the thickness of soft tissue and cortical bone. Fifteen maxilla from 15 cadavers were cut in midsagittal plane and buccopalatal plane to measure the thickness of soft tissue and cortical bone of midpalatal and maxillary posterior interdental areas. Sectioned samples were scanned and the thickness was measured. The thickness of soft tissue and cortical bone were measured at 6 points from the interdental papilla with 5-mm intervals in the mid-sagittal section. And, the thickness of soft tissue and cortical bone were also measured at 5 points from the alveolar crest with 1-mm intervals in the buccopalatal section. The mean and standard deviation of the measurement were calculated. Soft tissue thickness at the midpalatal suture area was 1.46 mm at 15 mm from the interdental papilla and remained uniformly thick posterior to this point, and steeply increased at 35 mm area posteriorly. Cortical bone thickness were greatest (2.13 mm) at 20 mm from the interdental papilla and remained uniformly thick posterior to this point, and decreased at 30 mm area posteriorly. Palatal soft tissues thickness in all groups was thinnest at the 1 mm from the alveolar crest and gradually increased from alveolar crest to apical portion. Cortical bone thickness in all groups was thickest at the 1 mm from the alveolar crest and slightly decreased from alveolar crest to apical portion. Buccal soft tissue thickness in all groups was thickest at the 1 mm from the alveolar crest and gradually decreased from alveolar crest to apical portion. Cortical bone thickness in all groups was thinnest at the 1 mm from the alveolar crest and slightly increased from alveolar crest to apical portion. Soft tissue thicknesses were greater on the palatal side than on the buccal side. Cortical bone thicknesses of the buccal side were thicker than the palatal side. These results provide anatomical data of soft tissue and cortical bone thickness to assist in the determination of safe location for the mini-implant placement in the midpalatal and maxillary interdental areasope