Comparison Of Accuracy Of Casts Fabricated By Different Impression Methods

Objective:This study in vitro aimed to compare the accuracy of traditional stone models,intraoral digital models and 3D printing models made by different impression methods.It provides references for the selection and application of different impression techniques in clinical practice.Methods:A standard dental study model(Dental Study Model 500 A,Nissin,Japan)was prepared with 12-22 for veneers restoration,the prepared model was scanned using an extraoral scanner(3shape D2000)and established as reference.Then the reference model was fastened to adental simulator,do it separately for the reference mode to obtain the corresponding work model:(1)8 digital impresions were taken with 3shape Trios intraoral scanne to obtain 8 intraoral digital modelsr;(2)8 silicone rubber impression was taken,poure with type IV plaster to obtain 8 stone models;(3)the 8 scan data generated by the intraoral scanner were printed with a 3D printer(lian tai S300,China),and 8 3D printed resin models were obtained.The 8 stone models and 3D printed models were scanned again with an extraoral scanner to obtain their three-dimensional data.Geomagic Qualify 2015 software was used for image analysis.The one-way variance analysis meyhod,LSD tests and independent sample t test were used to analyze the accuracy differences among the three groups of data.(Test leve α=0.05)Results:1.For the 12-22 veneer model,the truness of the intraoral scan group,the 3D printing model group,and the stone model group are 32.47±4.66μm,33.62±3.01μm,22.68±1.85μm,respectively;the precision is 20.61±7.94μm,21.82±5.71μm,23.70±3.51μm respectively.There was no significant difference in the precision of the three groups of models(P>0.05).There was no significant difference in the truness of the intraoral digital model group and the 3D printing model group,but they were all lower than the stone model group(P<0.05).2.For the full arch model,the truness of the intraoral scan group,the 3D printing model group,and the stone model group are 97.65±6.89μm,105.07±8.78μm,65.65±3.63μm respectively;the precision is 37.87±12.26μm,76.82±9.91μm,37.98±8.47μm respectively.The accuracy of the stone model group> the intraoral scanning group> the3 D printing model group(P<0.05);the precision of the intraoral digital printing module=the stone model group> the 3D printing model group(P<0.05).Conclusions:1.Among the three groups of models in this experiment,the stone model has the highest truness and precision.2.For the veneer model,the accuracy of the intraoral digital impression is comparable to that of the 3D printed model,but for the full arch model,the accuracy of the 3D printed model is not as accurate as the intraoral digital model.3.For veneer restorations,digital impression and 3D printing models can be considered.The digital impression method should be used with caution when it comes to precise restoration of the whole dentition.