Objective This study aims to compare the accuracy of self-developed universal implant guide(SDG),3D printed digital guide(DG),and free hand(FH)simulated implantation in the posterior tooth area of dental models.Methods Ten junior dentists were selected to place three implants in the 35,37,and 46 tooth sites of the mandibular models(35,36,37,and 46 missing teeth)by using SDG,DG,and FH,and the process was repeated again to take the av-erage value.Cone beam computed tomography(CBCT)was used to evaluate the global coronal deviation,global apical deviation,depth deviation,and angular deviation between the actual position and preoperative planned position.Re-sults The coronal deviation and apical deviation of the three implant sites in the SDG group were not significantly dif-ferent from those in the two other groups(P>0.05).The depth deviation and angular deviation in the SDG group were smaller than those in the DG group(P<0.05)and FH group(P<0.05),respectively.All deviations at site 37 in the SDG group were not different from those at site 35(P>0.05),while the depth and angular deviation at site 37 in the DG group were higher than those at site 35(P<0.05).Conclusion The precision of the self-developed universal dental im-plant guide can meet the requirements of clinical posteri-or implantation.

Transcrestal maxillary sinus floor elevation is an effective method to solve the problem of insufficient bone height in the posterior maxillary region.However,current methods,such as osteotome sinus floor elevation,cushioned grind-out technique,Smart Drill technique,etc.,require specialized surgical tool boxes.In this article,we introduce a new method of transcrestal maxillary sinus elevation that uses built-in reamers of various implant systems to scrap residu-al bone at the sinus floor and uses the implant to push the sinus membrane during implant placement.This technique is easy to operate and time saving and has a low rate of sinus membrane perforation.After a one-year follow-up observa-tion of 146 people and 175 implants,the endo-sinus bone gains were 5.00(4.70,5.30)mm and 2.10(1.40,2.70)mm in the group of 3 mm≤residual bone height(RBH)<5 mm and the group of 5 mm≤RBH<8 mm,respectively,which can meet the clinical requirements of implant stability.This technique is suitable in generalizing dental implantation.