Objective This clinical study aimed to evaluate the accuracy of a fully digital technique for mea-suring sagittal condylar inclination(SCI),as well as vali-dating whether differences existed between the left and right SCI values of the same participant,to provide a ref-erence for clinical practice.Methods Ten participants with good occlusal relationship and normal temporomandibular joint were recruited.Three methods were used to mea-sure the SCI values of the participants,namely,A(mechanical facebow transferring and mechanical articulator-based measuring method with physical protrusive interocclusal registration),B(face scan-based virtual facebow and virtual ar-ticulator-based measuring method with digital protrusive interocclusal registration),and C(jaw motion tracking system-based measuring method).With the group subjected to methods A and C as the control,the SCI values obtained by the three methods were statistically analyzed.The left and right SCI values of the same participant were also compared.Re-sults The left and right SCI values measured by method A were 41.70°±7.09° and 42.80°±8.62°,those by method B were 35.09°±12.49° and 37.63°±12.10°,and those by method C were 39.43°±8.72° and 38.45°±6.91°.No significant dif-ference existed among the SCI values measured by the three methods(P>0.05).Meanwhile,no statistical difference existed between the SCI values on the left and right sides of the same participant(P>0.05).Conclusion The accuracy of the virtual facebow and digital protrusive occlusal registration based SCI measuring method was the same as that of mechanical facebow based and jaw motion tracking system-based methods.The SCI values on the left and right sides of the same participant were similar.Clinically,an appropriate SCI measurement and setting strategy can be selected based on the actual situations.

Objective This clinical study aimed to as-sess the trueness of three intraoral scanners for the recor-ding of the maximal intercuspal position(MIP)to provide a reference for clinical practice.Methods Ten participants with good occlusal relationship and healthy temporomandibular joint were recruited.For the control group,facebow transferring procedures were performed,and bite registrations at the MIP were used to transfer maxillary and mandibular casts to a mechanical articulator,which were then scanned with a laboratory scanner to obtain digital cast data.For the experimental groups,three intraoral scanners(Trios 3,Carestream 3600,and Aoralscan 3)were used to obtain digital casts of the participants at the MIP following the scanning workflows endorsed by the corresponding manufacturers.Sub-sequently,measurement points were marked on the control group's digital casts at the central incisors,canines,and first molars,and corresponding distances between these points on the maxillary and mandibular casts were measured to calcu-late the sum of measured distances(DA).Distances between measurement points in the incisor(DI),canine(DC),and first molar(DM)regions were also calculated.The control group's maxillary and mandibular digital casts with the added mea-surement points were aligned with the experimental group's casts,and DA,DI,DC,and DM values of the aligned control casts were determined.Statistical analysis was performed on DA,DI,DC,and DM obtained from both the control and ex-perimental groups to evaluate the trueness of the three intraoral scanners for the recording of MIP.Results In the con-trol group,DA,DI,DC,and DM values were(39.58±6.40),(13.64±3.58),(14.91±2.85),and(11.03±1.56)mm.The Trios 3 group had values of(38.99±6.60),(13.42±3.66),(14.55±2.87),and(11.03±1.69)mm.The Carestream 3600 group showed values of(38.57±6.36),(13.56±3.68),(14.45±2.85),and(10.55±1.41)mm,while the Aoralscan 3 group had val-ues of(38.16±5.69),(13.03±3.54),(14.23±2.59),and(10.90±1.54)mm.Analysis of variance revealed no statistically sig-nificant differences between the experimental and control groups for overall deviation DA(P=0.96),as well as local devi-ations DI(P=0.98),DC(P=0.96),and DM(P=0.89).Conclusion With standardized scanning protocols,the three intra-oral scanners demonstrated comparable trueness to traditional methods in recording MIP,fulfilling clinical requirements.