Study On Trueness And Influencing Factors Of Impression Technology Of Scannable Healing Abutment

Objective:Passive fit was crucial to the long-term success rate of implant protheses,and impression was the most critical link to the passive fit of implant protheses.This study aimed to compare trueness of impression technology of scannable healing abutment with that of scan body and conventional open-tray method,and to evaluate effects of the four factors（implant number,implant angulation,multiple use and surface modification of the abutment）on trueness and precision of impression technology of scannable healing abutment.It was available to select the applicable implant impression technology.Materials and methods:This study included two parts,both using 3D printing resin models with analogs as reference models,and reference data were obtained with the rainbow^TM scanner.In the first part:trueness comparisons among different impression technologies,scannable healing abutments and scan bodies were respectively connected to analogs in the reference model,scanned with the TRIOS 3scanner,and then 3D printing resin models with analogs were made as test models.Impression posts were also connected to analogs in the reference model,and then gypsum models with analogs were made by open tray and vinyl polysiloxane material as test models.All 30 test models（n=10 each group）with scan bodies were scanned with the TRIOS 3 scanner to obtain test data.In the second part:effects of implant number（1,2,4）,implant angulation（0°,10°,20°）and multiple use of the abutment（1,5,10,15,20 times）on trueness and precision,test data were obtained by scanning every reference model with scannable healing abutments 10 times with TRIOS 3scanner;in experiment of the effect of surface modification of the abutment（modification,non-modification）on trueness and precision,test data were obtained by scanning reference model with scannable healing abutment 10 times with TRIOS 3and CS 3600 scanners,respectively.All data were imported into the Geomagic Qualify 2013 software,and the 3D deviation compare was used to calculate accuracy（trueness and precision）.Test data were superimposed onto the corresponding reference data for trueness,while test data in the same group were superimposed onto each other for precision.Data were statistically analyzed by one-way ANOVA or independent samples t-test.Results:1.Trueness of impression technology of scannable healing abutment,scan body and conventional open-tray method was 65.6±23.8μm,64.7±25.3μm and 60.0±21.1μm,respectively（P>0.05）.2.Trueness of 1,2 and 4 implants was 24.5±9.7μm,47.1±14.7μm and 105.7±28.3μm,respectively（P<0.05）,with precision of 11.1±1.6μm,19.1±7.9μm and 33.1±7.8μm,respectively（P<0.05）.3.Trueness of the implant tilted at 0°,10°and 20°was 18.5±8.4μm,21.9±9.8μm and 36.3±14.4μm,respectively,with precision of 11.3±2.6μm,16.0±3.1μm and 17.1±4.7μm,respectively.Trueness was significantly better under 0°and 10°conditions than 20°（P<0.05）,with no significant difference between 0°and 10°（P>0.05）.Meanwhile,precision was significantly worse under 10°and 20°conditions than 0°（P<0.05）,with no significant difference between 10°and 20°（P>0.05）.4.Trueness of the abutment reused 1,5,10,15 and 20 times was 13.8±0.5μm,14.7±1.5μm,17.2±1.1μm,19.7±3.0μm and 32.4±11.3μm,respectively,with precision of 11.3±1.0μm,12.0±1.3μm,14.1±2.2μm,21.5±1.4μm and 21.5±1.6μm,respectively.Trueness decreased significantly when the abutment was reused20 times（P<0.05）.Precision decreased significantly when the abutment was reused15 and 20 times（P<0.05）,with no significant difference between 15 and 20 times（P>0.05）.5.When scanned with TRIOS 3 scanner,trueness of the surface-modified and non-surface-modified abutment was 24.8±6.3μm and 24.4±10.0μm,respectively（P>0.05）,with precision of 11.9±3.6μm and 10.4±2.3μm,respectively（P>0.05）.When scanned with CS 3600 scanner,trueness of the surface-modified and non-surface-modified abutment was 14.0±3.3μm and 34.7±13.7μm,respectively（P<0.05）,with precision of 14.7±4.4μm and 32.2±10.6μm,respectively（P<0.05）.Conclusions:1.Trueness of impression technology of scannable healing abutment was similar to that of scan body and conventional open-tray method.The emerging technology could avoid the frequent installation and dismantlement of accessories,so it could be used as an alternative to the implant impression technology.2.The impression technology of scannable healing abutment could be affected by the four factors（implant number,implant angulation,multiple use and surface modification of the abutment）.Trueness and precision of this technology decreased as implant number increased.It was recommended that the inclination of the implant should not exceed 20°.Reusability of the abutment should be limited to 15 times.The surface-modified abutment exhibited better trueness and precision when scanned with the specific scanner.