The Influence Of Implants Spacings And Splinting Methods On The Accuracy Of Abutment-level Implant Impressions

Objective1.To compare the accuracy of implant impressions made by different implant spacing and different splinting methods;2.To evaluate the effect of different splinting methods and different implants spacings on the accuracy of multiple-unit abutment-level implant impressions.Materials and Methods:A resin edentulous model with material strength simulating to the bone density of grade Ⅱ to Ⅲ work as the reference model of this study.The model base and 4 tray limit slots were made with autopolymerizing acrylic resin.6 parallel implant holes At 1cm,2cm and 3cm intervals were prepared with a horizontal grinder at the alveolar ridge,then 6 implants(Nobel Active 4.3*11.5mm)were placed.Multiple-unit abutment were connected to each implant.The implants were located in: Group A(1cm: right upper jaw second premolar and first molar.Group B(2cm): right upper jaw central incisor and first premolar;Group C(3cm): left upper jaw lateral incisor and first molar.Making impressions with four different kind of splinting methods of impression copings(n = 10): 1.nonsplint;2.Dental floss resin splint;3.Prefabricated resin bar sectioned and resplint;4.Metal rod splint.Finally,a total of 40 experimental models were obtained.The reference model and the experimental models were scanned in a high-precision scanner(3shape D810)to get the digital models.The data was disposed by Geomagic Studio 2013,The cylinder of scanning rod in each spacing group is extracted.According to the characteristics of the cylinder,the scanning rods of the experimental groups and the control groups were superimposed to obtain the 3D deviation value.Evaluating the influence of different splinting methods and different implants spacings on the accuracy of multiple-unit abutment-level implant impressions.One Way AVONA and LSD multiple comparison analysis were performed,and p < 0.05 was statistically significant.Results:1.the accuracy of different implants spacings : Group A>Group B >Group C,Group A was the most accurate.However,when the splinting method of the impression copings was different,the statistical difference was different.When it was the nonsplint and the dental floss resin splint,the difference between A and C was statistically significant(p < 0.05).When it was the metal rod splint,there was statistical difference between A and B,and A and C(p < 0.05).When it was the Prefabricated resin bar cut off and resplint,there was no statistical difference in the spacing between AB,AC and BC(p=0.314,0.059 and 0.353).2.Method prefabricated resin bar cut off and resplint showed the highest accuracy followed by metal bar splint,dental floss resin splint,and nonsplint.When the spacing was A(1cm),there was significant statistical difference between the prefabricated resin bar sectioned and resplint and the dental floss resin splint(p < 0.01),but no significant statistical difference(p=0.08)between the the prefabricated resin bar sectioned and resplint and metal bar splint,there were significant statistical differences between metal bar splint and dental floss resin splint and nonsplint(p < 0.05).When the spacings ware B(2cm)and C(3cm),there were statistical differences between the prefabricated resin bar cut off and resplint and the other three splinting methods,but the differences between the other three groups was not statistically significant.Conclusions:1.The increase of implanting spacing will reduce the accuracy of the abutmentLevel implant impressions.2.Among the four splinting methods,the prefabricated resin bar sectioned and resplint is the most accurate,followed by metal bar splint,dental floss resin splint,nonsplint.3.when the implants spacing is relatively short(1cm),splinting the impression copings with metal bar、dental floss resin and prefabricated resin bar sectioned and resplint can get higher impression accuracy than nonsplint.when the implants spacing is 2cm and 3cm,the accuracy of implant impression made by splinting the impression copings with metal bar 、 dental floss resin reduced significantly.Thus,splinting impression copings with resin resplint can obtain more accurate abutment-level implant impressions,especially when the implant sites are far apart.