Evaluation Of The Fit Of Pure Titanium Crown 3D-printed By Electron Beam Melting(EBM) Technology:in Vitro And Vivo Study

Electron beam melting(EBM) is a kind of 3D printing,making the material melt completely after cooling solidification molding,which is a manufacturing method of 3D entity parts and its processing uses electron beam as a heat source.Compared with the SLM technique based on laser energy, EBM has many advantages,such as high energy utilization rate, high power density, high efficiency, no reflection and vacuum environment pollution-free.Compared with the CAD/CAM technology,EBM saves the production cost and time, and can process a variety of complex structure parts. EBM technology avoids the cumbersome process and casting defects contrast to lost wax technique(LW).Electron beam melting, with its unique technical advantages will become a metal manufacturing technology of the future development prospects.At first,to evaluate the pure titanium crown fit of EBM technology in vitro,this research adopts the SLM, CAD/CAM technology and lost wax technique method as control.Secondly, I compare the roughnessand polishing effect of pure titanium specimens fabricated by EBM and the lost wax casting and choose some suitable patients in clinic, to compare the pure titanium single crown fit of EBM and casting in the mouth, comprehensively making a evaluation of the fit of EBM pure titanium crown, so as to provide the basis for the clinical application of EBM technology.Method1 An standard metal model was produced.Pure titanium respectively fabricated by five different techniques:electron beam melting(EBM),selective laser melting(SL M),CAD/CAM technology(DMG,R+K) and conventional lost wax(LW) method.The space between the crown and the abutment teeth was copied by a light-body silic one,which was cut into 1 mm thin specimen.The thickness of marginal gaps(MG) a nd internal gaps(IG) was measured using a stereomicroscope.The data were statistic aly analysed by ANOVA and SPSS statistical package version 17.0.2 Pure titanium specimen fabricated by electron beam melting(EBM) and the l ost wax casting(LW) technique for ten samples in each group,the roughness of whi ch was measured by three-dimensional topography measurement meter.The results w ere analysed by SPSS statistical package version 17.0.At the same time,comparing t he effect after the conventional polishing.3 One dentist prepared ten teeth that were from ten patients in clinic.Pure tita nium crowns were fabricated by electron beam melting(EBM) and the lost wax cas ting(LW) technique.Taking the crown in the patient after cleaning and polishing and making clearance thin film,which was measured by a stereomicroscope.The data we re analysed by two independent sample t-test.Results1.The measurement results of pure titanium single crowns,three units union crowns and six units union crowns fabricated by five methods show that marginal gap is least and internal gap is largest.2.There are statistically significant differences of marginal gap in five groups ofpure titanium single crowns(P<0.05).The marginal fit of CAD/CAM group is the best among the five groups,followed by EBM and SLM group. There are no statistically significant differences of marginal gap in EBM and SLM,DMG and R+K.And that there are no statistically significant differences of internal gap in five groups of pure titanium single crowns(P>0.05).3.There are statistically significant differences of marginal gap in five groups of three units union crowns(P<0.05).The marginal fit of CAD/CAM group is the best among the five groups,followed by SLM group,but the EBM group is the worst. There are no statistically significant differences of marginal gap in DMG and R+K.There are no statistically significant differences of internal gap in EBM and SLM,R+K.The internal gap of EBM is more poor than DMG and the lost wax casting method.4.There are statistically significant differences of marginal gap in five groups of six units union crowns(P<0.05).The marginal fit of CAD/CAM group is the best among the five groups,followed by SLM group,but the EBM group is the worst.There are no statistically significant differences of marginal gap in DMG and R+K(P>0.05).There are no statistically significant differences of internal gap in EBM,SLM,DMG and R+K.5.There are statistically significant differences of marginal gap in pure titanium single crowns,three units union crowns and six units union crowns of EBM and DMG;and that in six units union crowns and single crowns,three units union crowns of SLM and the lost wax casting method;and that in single crowns and three units union crowns, six units union crowns of R+K.6.The roughness of pure titanium specimen fabricated by EBM is larger than it in the cast group.There are no statistically significant differences in EBM and the cast group after polishing.7. The fit of pure titanium crown fabricated by electron beam melting in the clinic study showed that marginal and internal gap of two groups can satisfy the requirements.There are statistically significant differences of marginal gap,central axial plane and internal overall fit in EBM and cast.The fit of EBM group is worse than it of the cast group. There are no statistically significant differences of mean occlusal gap in twogroups.ConclusionThe pure titanium crowns made of EBM technology can meet the clinical requirements and it will hope to be a new technology of dental restoration system.