Manufacturing And Accuracy Analysis Of Digital Occlusal Splint For Orthognathic Surgery

Objective:The purpose of this experiment was to made digital occlusal splint for orthognathic surgery under computer-assisted technology,it was based on the Cone Beam Computed Tomography(CBCT)data of the patient's skull and the laser scanning surface data of the dental arch plaster model.To evaluate the accuracy difference of digital occlusal splint between single software and multiple software,and to explore the clinical application value.Methods:1.Ten patients with dental and maxillofacial deformities who met the inclusion criteria were selected at the Department of Oral and Maxillofacial Surgery of Affiliated Stomatological Hospital of Kunming Medical University from June 2017 to February 2019.All patients undergo orthodontics before orthodontic surgery,and were scanned with the Italian New Tom CBCT,ranged from the top of the skull to the chin,and made a plaster model of dental arch for three-dimensional(3D)laser scanning.(1)All patients were subjected to 3D reconstruction of the craniofacial model used ProPlan CMF 1.4 and fused with the scan data of the dental arch plaster model to obtain a composite model with the accuracy of dental surface.After 3D measurement,simulate osteotomy,move bone segments and other operations.Finally,a one-time single sofi-ware digital occlusal splint was generated;(2)Mimics 19.0 was used for 3D reconstruction,the model was imported into Geomagic studio 2014 to repair the model,and then the scan data of the dental arch plaster model were fused with the model to obtain a composite model with the accuracy of dental surface,which was used to simulate osteotomy and move bone segments,etc.At the same time,Magics 21.1 generated a "blank occlusal splint" of the dental arch shape,and finally use the Boolean logic reduction tool to generate a multi-software digital occlusal splint in Mimics 19.0;(3)Mimics 19.0 was used to generate the information of dental impression as a reference standard,it was based on the scan data of dental arch plaster model and the shape was sinilar to digital occlusal splint;(4)Simultaneously,the traditional occlusal splint was manufactured by plaster model surgery.2.The single software digital occlusal splint and multi-software digital occlusal splint were imported into Geomagic studio 2014 to evaluate the accuracy of the two methods by fusing with dental impression information of dental arch plaster model.The single software digital occlusal splint and the traditional occlusal splint were disinfected,and then brought to the operating table together.The single software digital occlusal splint was used to perform the operation,and its clinical application value was evaluated by the traditional occlusal splint.Results:Ten patients were used to manufactured two kinds of digital occlusal splint,the traditional occlusal splint and dental impression information reference standard of dental arch plaster model.1.When the dental fossa was used as the reference marker,the average of maximum fusion error of the single software digital occlusal splint was 0.0111±0.003 8mm in maxilla and 0.0107±0.0037mm in mandible;The average of maximum fusion error of the multi-software digital occlusal splint was 0.1333±0.0208 mm in maxilla and 0.1288±0.0246 mm in mandible.The fusion degree between the digital occlusal splint and the reference standard,that made by single software was better than that made by multiple software(P<0.001).Whether it was single software digital occlusal splint or multi-software digital occlusal splint,there was no significant difference neither between maxilla and mandible(P>0.05),nor between middle and final splint(P>0.05).2.When the single software digital occlusal splint and the traditional occlusal splint were used to simulate the occlusal movement during the operation,the occlusion matches well,and there was no case that the occlusal splint can't be brought in.Conclusion:In this experiment,CBCT data and plaster model surface data were fiused to improve the accuracy of dental surface,and the whole manufacturing process of orthognathic digital occlusal splint was introduced,which made the steps of digital orthognathic surgery more complete.The results show that the accuracy of digital occlusal splint made by single software is higher than that made by multiple software,suggesting that doctors should minimize data conversion and reduce data loss during pre-operative simulation.