Optimal Sites For Orthodontic Mini-implant Placement In Maxillary Anterior Region Assessed By Cone Beam Computed Tomography

ObjectiveThe purpose of this study was aimed to analysis the appropriate clinical implantation site of mini-implant anchorage in maxillary anterior region by using cone-beam CT, to provide a reference for the clinicians to choose the diameter and length, and to determine the angle and the most appropriate implantation site of mini-implant anchorage. MethodsThirty samples from the affiliated Huizhou Stomatological Hospital of Jinan University patients 30, 15 men and 15 women, age 18 to 30 years old, the han nationality were selected. These samples were scanned by the CBCT and input the CT data into Ez3D2009 version 1.0 software(VATECH,Korea). The required cross-section was segment from the three-dimensional image reconstruction, then take the following measurements: To select 2 mm, 4 mm, 6 mm, 8 mm fault from the top of the alveolar crest in maxillary anterior region(between the incisor, between incisor and lateral incisor, between lateral incisor and canine), labial alveolar bone thickness, mesiodistal distance, labial cortical bone thickness and labial alveolar bone density of the corresponding cross-section were measured.Application SPSS 13.0 software for statistical analysis. Results1. The difference between before and after each measured value has no statistical significance(P> 0.05).2. The difference between male and female each measured value has no statistical significance(P > 0.05).3. The difference between left and right on both sides of the measured value has no statistical significance(P > 0.05).4. In maxillary anterior region, the largest part of the bone mass at the mesiodistal distance is between the incisor from the alveolar crest at 8 mm(3.54±0.40 mm mm), the smallest part is between incisor and lateral incisor from the alveolar crest at 2 mm(1.75±0.32 mm). The largest part of the bone mass at the labial alveolar bone thickness is between incisor and lateral incisor from the alveolar crest at 8 mm(7.62±0.14 mm), the smallest part is between the incisor from the alveolar crest at 2 mm(5.18±0.17 mm). The largest part of the bone mass at the labial alveolar bone density is between the incisor from the alveolar crest at 2 mm(845.57±96.10 HU), the smallest part is between the lateral incisor and canine from the alveolar crest at 8 mm(601.71±99.38 HU). The largest part of the bone mass at the labial cortical bone thickness is between the lateral incisor and canine from the alveolar crest at 6 mm(1.23±0.21 mm), the smallest part is between the incisor from the alveolar crest at 2 mm(0.81±0.24 mm). Conclusions1. In the maxillary anterior region, the measurements of the mesiodistal distance and labial alveolar bone thickness showed a consistent increase in the studied sites when moving apically. While the measurements of the labial alveolar bone density showed a consistent decrease in the studied sites when moving apically. The measurements of the labial cortical bone thickness showed a decrease between the lateral incisor and canine from the alveolar crest at 6 mm and 8 mm, but other implantation sites showed a consistent increase when moving apically.2. The most narrow mesiodistal distance is between the incisor and lateral incisor, when to implant the mini- implant anchorage, should choose smaller diameter mini-implant(≤1.2 mm).3. For all measurements, the results of this study showed that between the incisor the mesiodistal distance and the labial alveolar bone density are the biggest, but the labial cortical bone thickness is the smallest; between the lateral incisor and canine the labial cortical bone thickness and the labial alveolar bone thickness from the alveolar crest at 2 mm, 4 mm, 6 mm are the biggest, but the labial alveolar bone density is the smallest. Therefore, in this study the best implantation sites are 1-1 and 2-3.