The Research On Denture Forming Based On Stereolithography For An Aqueous-Based Ceramic Suspension

At present,the casting and CAD/CAM methods are the main methods for ceramic denture molding.The casting process is time-consuming and laborious,and it is difficult to ensure the accuracy of the complex surface morphology of the denture.The surface and subsurface damage of porcelain is easily caused by CAD/CAM machining.SLA rapid prototyping technology,however,adopts the method of line-plane-body progressive prototyping,which requires no mold or machining,and has high molding speed and precision.Therefore,SLA technology was applied to broad prospects for denture molding field,UV curing characteristics of the ceramic slurry is the basis of molding denture,curing characteristics determine whether denture curing,degreasing and sintering process of the ceramic green body affects the surface quality and performance of the denture,in this paper,UV-curable aqueous ceramic slurry characteristics,curing characteristics and sintering for denture forming was studied the following aspects:?1?In view of the high viscosity of ceramic paste and the agglomeration of ceramic nanoparticles in the liquid phase,the viscosity of the ceramic paste was reduced by adjusting the viscosity of the premix,and the nano 3Y-ZrO₂ powder was modified by silane coupling agent KH570 to disperse evenly.The experimental results showed that all the active monomers could increase the viscosity of premix.Among them,TMPTA,which was soluble with PUA,had the least impact on the viscosity of premix,followed by HDDA and TPGDA.The curing thickness curve of premix was obtained through different mass ratios of HDDA and TMPTA,and the mass ratio of active monomer HDDA and TMPTA in premix was 1:2after comprehensive consideration.After powder modified by transmission electron microscope found that the surface coated with a organic molecules layer of about 5nm thick,and found narrow particle size distribution,modified powder slurry in ultrasonic 60min,the average particle size was 108.8nm,minimum value.Meanwhile,thermogravimetric analysis found that after 350?,the modified particle weightlessness,and modified slurry RSH value is higher.?2?In view of the curing characteristics of aqueous ceramic slurry,the effects of different parameters on the contour of single curing line were studied from the perspective of single scanning curing line.It was found that the higher the solid content of ceramic slurry was,the smaller the linear shrinkage and volume shrinkage were.The curing width and curing thickness of ceramic pastes increased with the increase of TPO concentration,decreased with the increase of solid content,increased with the increase of particle size,and decreased with the increase of scanning speed.When the concentration of TPO was higher than 1.1wt%,there was no significant change in the width and thickness,and there was a linear relationship between the curing thickness and curing width of a single scanning curing line and the particle size of powder.And the scanning speed showed a negative exponential relationship.?3?In view of the degreasing and sintering of denture blanks,the degumming temperature of the ceramic body was determined by thermogravimetric analysis to be 550?.When the final firing temperature was 1500?,the hardness of the sample was 1022HV,and the bulk density was 5.71 g/cm³,the relative density is 93.61%,the flexural strength of the sample is 562.6MPa,which satisfies the mechanical properties of ZrO₂ ceramics as an oral implant material.The cross-sectional energy spectrum analysis shows that only O and Zr elements exist in the sample,which meet the requirements of as human implants.Through in vitro friction and wear experiments,it was found that the depth,width and wear loss of SLA dentures were smaller than those of natural teeth.