Analysis Of Bone Around Buccal Roots Of Maxillary Molars For Miniscrew Placement For Whole Dentition Distalization Using Cone Beam Computed Tomography

Distalization of molar group or the whole dentition is a new method which is different from the traditional method of molar distalization one by one. There have been several scholars at home and abroad trying to use a variety of anchorage devices for distal movement of molar group or the whole dentition to achieve non-extraction treatment for adults or young people. One certain scholar believes that miniscrews in the buccal bone around the mesial buccal roots of maxillary second molars will not prevent molar distal movement, which is a good new technology. Our study aimed to give a comprehensive analysis on the feasibility of miniscrew placement in the buccal bone around maxillary molar roots for whole dentition distalization.Security of implantation and the amount of distalization are two keys of whole dentition distalization using miniscrews in the buccal bone around buccal roots of maxillary molars. The percentages of safety placement of miniscrews in the buccal bone around buccal roots of maxillary molars in orthodontic patients can reflect the security of implantation, the anterior interradicular space along the arch of each site can reflect the amount of distalization. Pretreatment CBCT images of88orthodontic patients were selected according to certain inclusion criteria, which were divided into two groups according to the number of the buccal root of maxillary second molars. The actual buccal bone thickness around the buccal roots of maxillary molars and bone thickness necessary for miniscrew placement there with the angle of70°to the maxillary occlusal plane were measured. Upon comparison of the two data, the percentages of safety placement in patients were calculated. The interradicular space along the arch was measured for analysis of the available amount of distalization. The results indicate that in all the buccal areas there were certain percentages of patients could be inserted miniscrews safely. In the group of patients with two-buccal-root maxillary second molars, the highest safety rate of85.70%, was around the mesiobuccal root of maxillary second molars; in the group of patients with single-buccal-root or fused root maxillary second molars, the highest safety rate of91.38%, was around the maxillary second molar roots. The interradicular space along the arch in front of the mesial buccal roots was large, and that in front of the distal buccal roots was small.In conclusion, in all the buccal areas miniscrews can be inserted, and the best buccal area is around maxillary second molar roots. Nevertheless, there isn’t an absolutely safe area. The application of dentition distalization by miniscrews in the buccal area of maxillary molar roots needs individual analysis.