Application Of Integrated Digital Maxillodental Model In Computer Aided Design And Manufacturing Of Individualizsd Miniscrew Surgical Guides

Objectives:Due to the lack of clear understanding on implant regional anatomy,the failure rate of implantation is high.The miniscrews contact with the adjacent tooth roots is the main factor.The aims of this article were to establish a high-precision three-dimensional(3D)integrated maxillodental model by matching CBCT model with 3D digital maxillodental model using 3D automatic registration method,based on which,we designed and manufactured individualized miniscrew surgical guides,then apply it to clinical miniscrews placement,in order to improve the precision of implant,avoid root injury and reduce the failure rate.Methods:Part one:From July 2016 to May 2017,6 patients in Guangxi Medical University Stomatological Hospital with malocclusion were scanned by CBCT,and the silicon models scanned by laser,which then created the 3D dental models.The digital integrated dental models were established by integration of these models by Geomagic studio 12.0.Based on this integrated model,we designed the digital miniscrews analogue and precisely implant it by digital.Then,Individualized miniscrew surgery guides were designed by 3-matic 8.0 software.Finally,all data we obtained were output to make the resin template using rapid proto-typing technology.The inner diameter of the guide track was detected by a vernier caliper.Part two:From July 2016 to July 2017,12 patients in Guangxi Medical University Stomatological Hospital with malocclusion were selected.One side of each patients' maxillary(experimental group,n = 12)was randomly selected to implant miniscrew by using individualized miniscrew surgery guides.The other side(control group,n = 12)located the miniscrew by X-ray film.By overlapping preoperative and postoperative CBCT scanning 3D model,the deviation between actual and planned placements were measured as 3D angular deviations and distance(coronal and apical)deviations.The security and stability of miniscrews implantation was evaluated.Results:1 We have established a high-precision integrated 3D dental and maxillary models including crown,root and gingiva.Based on the integrated model,we have completed the computer aided design and manufacturing of the individualized miniscrew surgical guides.2 The inner diameter of the guide track was(1.799±0.23)mm.3 All the resin surgical guides were suitable.The implant was fit with the buccal side.4 In the surgical guides group,the angular deviation was a mean of(4.97± 1.79)°,and the distance deviations in the coronal and apical areas were mean of(0.98±0.30)mm and(1.03±0.22)mm.All of the measurement error was not statistically significant(P>0.05).5 In the experimental group,83.3%of the miniscrews were located in the middle of the two teeth,there was no root damage from miniscrew placement.And all the miniscrews did not fall off.While in the control group,only 33.3%of the microimplant was located in the middle of the root of the tooth,and two miniscrews loosed.Conclusions:The accuracy of individualized miniscrew surgical guides were high.Miniscrews were placed more accurately when using surgical guides than when using a direct method reference to the periapical X-ray.This research provides guidance and help to improve safety,stability and success rate of miniscrews implantation.