Cortical Bone Thickness for Mini-implant Placement in Korean

Recently, mini-implant is popular in the orthodontic treatment due to its simplicity and convenient surgical procedure. The objective of this study is to provide the anatomical guideline for mini-implant placement by analysing the cortical bone thickness in Korean. Hemi-sections of sixteen maxillae and twenty-two mandibles with normal teeth were used. Interdental areas between the 1st premolar and the 2nd premolar (Group 1), the 2nd premolar and the 1st molar (Gruop 2), and the 1st molar and the 2nd molar (Group 3) were sectioned and then scanned. After setting the axis of teeth, the cortical bone thickness was measured at the distance of 2 mm, 4mm, 6 mm, and 8 mm from alveolar crest. The mean thickness of cortical bone in the maxilla according to distance from alveolar crest was 1.30 +/- 0.63 mm (2 mm), 1.49 +/- 0.62 mm (4mm), 1.72 +/- 0.64 mm (6mm), and 1.90 +/- 0.90 mm (8 mm) at the buccal side and 1.33 +/- 0.47 mm, 1.31 +/- 0.45 mm, 1.37 +/- 0.55 mm, and 1.39 +/- 0.58 mm at the palatal side. In the mandible, that was 3.14 +/- 1.71 mm, 4.31 +/- 2.22 mm, 4.23 +/- 1.94 mm, and 4.30 +/- 1.57 mm at the buccal side and 1.98 +/- 0.88 mm, 2.79 +/- 1.01 mm, 3.35 +/- 1.27 mm, and 3.93 +/- 1.38 mm at the lingual side. The buccal cortical bone thickness in the maxilla was decreased from Group 1 to Group 3, while the thickness of palatal side was no change. In the mandible, it did not show a tendency at the buccal side and it was decreased from Group 1 to Group 3 without significant difference at the lingual side. Therefore, the buccal side of the Group 1 and Group 2 in both the maxilla and mandible seems to be the most appropriate site for a mini-implant placement with taking the stability and retention.

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

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 areas.

Effect of NFI-C on the Expression of Smad and TGF-betaR1 / 대한해부학회지

NFI-C null mice demonstrate aberrant odontoblast differentiation and abnormal dentin formation, and thus develop molars lacking roots. However, other tissues and organs in the body including ameloblasts appear to be unaffected. Abnormal dentin in NFI-C null mice shares morphological similarities to the osteodentin that is formed in dental caries. However, little is known about the relationship between NFI-C and osteodentin formation. In this study, to elucidate the molecular characteristics of abnormal odontoblast in NFI-C null mice, we examined the levels of Ask-1, Cdc-2, Smad2/3, and TGF-betaR1 in cell culture and tissue sections from NFI-C null mice using immunofluorescence and immunohistochemistry. NFI-C protein was localized in the nucleus and cytoplasm of normal odontoblasts in vitro. Ask-1 and Cdc-2 proteins were shown in the perinuclear cytoplasm of both normal and NFI-C null mice. There were no differences in the pattern of production of Ask-1 and Cdc-2 proteins between normal and NFI-C null mice. Smad2/3 was not found in the odontoblast and subodontoblastic cells of the normal mice, whereas NFI-C null mice showed Smad2/3 immunoreactivity in the odontoblasts and subodontoblastic cells of the tooth pulp. TGF-betaR1 was weakly immunopositive in the odontoblast and subodontoblastic cells of normal mice, whereas it was detected strongly in the subodontoblastic cells of the NFI-C null mice. These results suggest that disruption of NFI-C increased the expression of Smad2/3 and TGF-betaR1 in developing odontoblasts and consequently caused abnormal dentin formation, similar to osteodentin.