Comparative Study On Jaws Localization Accuracy Of Two Kinds Of Digital Bite Plates

Objective:To perform a deep research on the design and the production of digital bite plate and improve the jaws localization accuracy of the digital bite plates.Methods:Thirty patients with dental and maxillofacial deformities were selected,and the basic information of the patients was collected for clinical examination.Meanwhile,cranial anteroposterior,lateral radiographs,panoramic radiographs,maxillary and mandibular dentition models and cranio-maxillofacial CT scan were collected before surgery.CT data is stored and transmitted in DICOM file form.Two groups of digital full-tooth models were obtained by intraoral scanning of natural dentition and in vitro scanned plaster model.Afterwards,the digital full-tooth models and the cranio-maxillofacial CT data were imported into Mimics Medical 20.0 software.The two groups of digital occlusal models were fitted with the cranio-maxillofacial digital models reconstructed by CT data respectively,and the maxillofacial 3D digital models were used to perform virtual cutting and bone removal for the upper and lower mandibular bone respectively.The dental information in the craniofacial 3D digital model was replaced by the digital model obtained by oral scanning,and on this basis,the oral scanning occlusal guide plate(the middle occlusal guide plate and the terminal occlusal guide plate)were made.The dental information on the craniofacial 3D digital model was replaced by the digital model registration obtained from the invitro scanning,and on this basis,the occlusal guide plate of the in vitro scanning was made,including the middle occlusal guide plate and the terminal occlusal guide plate.Then the two groups of occlusal guide plates were 3D printed,and the virtual design position of maxilla was confirmed and verified by computer aided navigation system during the operation.Intraoperative navigation recorded the coordinates of the marking points of the two sets of occlusal guide plates for positioning the jaw,and calculated the distance deviation(DE)between the actual data and the design data of the seven jaw measurement points.The measurement points of the upper and lower jaw were:A(upper alveolar seat point),FPR(Front Punch Point-R),FPL(Front Punch Point-L),RPR(Rear Punch Point-R),RPL(Rear Punch Point-L),FR(Foramen-R),FL(Foramen-L).The corresponding accuracy of the two groups of digital bite plates was evaluated by the adaptability,deviation analysis(RMS)and volume of the occlusal guide plate and intraoperative navigation data analysis.Result:The marginal integrity of the bite plate from plaster model scanning is considerably lower than that from intraoral scanning.The difference of the adaptability between the two bite guide plate groups(χ~2=22.308,P<0.01)is statistically significant.Taking the CT bite plate a reference,the RMS of the bite plate from plaster model scanning=224.57±52.31μm,the RMS of the bite plate from intraoral scanning=189.20±35.91μm,the difference of the RMS between the two bite plate groups(t=2.086,P<0.05)is statistically significant.The difference of the volume among the two groups(P<0.01)is statistically significant.Pair analysis of navigation coordinates of upper and lower mandibular markers:On the X-axis,the difference between MDE and ODE in one study marker(A)was statistically significant(P<0.05),the absolute value of the median of MDE was greater than that of the median of ODE,and the accuracy of jaw relocation in the occlusal plate group from plaster model scanning was better than that from intraoral scanning;On the Y-axis,the difference between MDE and ODE in five study marker(A、FPR、FPL、RPR、RPL)was statistically significant(P<0.05),the absolute value of the median of MDE was greater than that of the median of ODE,and the accuracy of jaw relocation in the occlusal plate group from plaster model scanning was better than that from intraoral scanning;On the Z-axis,there was no statistically significant difference between MDE and ODE in 7 marker points(A、FPR、FPL、RPR、RPL、FR、FL)(P>0.05).Conclusion:The marginal integrity and the accuracy of the bite plate as well as the natural dentition from intraoral scanning is higher than that from plaster model scanning,resulting in its localization of the reduced upper and lower jaws superior to that of plaster model.The accuracy and positioning accuracy of the bite guide plate from intraoral scanning is better than that from plaster model scanning.