| Objective:to study the effects of polishing,glazing and sandblasting on two body wear ability of the zirconia all-ceramic crowns.In order to guide the clinical selection of better surface treatment on zirconia all-ceramic crowns to reduce the abrasion of zirconia all-ceramic crowns and natural teeth.Methods:1.Scanned preparation body model of the right mandibular first molars by3 Shape scanner,fifteen PMMA preparation dies were fabricated by CAM milling machine.2.Scanned preparation body model of the right mandibular first molars by3 Shape scanner,zirconia all-ceramic crowns were made by CAD/CAM system,fifteen specimens were randomly divided into three groups(polishing,glazing and sandblasting),there were 5 specimens for each group.ALL specimens were bonded to PMMA preparation body dies.3.Fifteen freshly removed maxillary first premolars with no difference in hardness(P>0.05,α= 0.05)were selected.The non-functional buccal part of the teeth was embedded in the resin to produce a cylindrical base with a diameter of 6.2 mm and a height of 10 mm.All specimens were polished for20s and randomly divided into three groups(five specimens for each group),and pared with zirconia all-ceramic crown.4.Three groups of specimens were tested by UMT-3 tribometer in the artificial saliva environment.The experimental frequency was 0.2Hz and the loading force was 10 N,and testing time was 1 hour.5.The quality of each sample was measured before and after the experiment.The dynamic friction coefficient of each sample were recorded by software.The results of the three experimental groups were compared and analyzed.6.One sample was selected from each of the 3 experimental groups.The surface morphology was observed by scanning electron microscope(SEM).Results:There was significant difference between the quality loss of three groups of zirconia all-ceramic crowns(P<0.05).The ranking of the quality loss of three groups from the least to the most was : sandblasting group,polishing group,glazing group.2.There was no significant difference between the quality loss of three groups of paired teeth(P>0.05).The ranking of the quality loss of three groups from the least to the most was: polishing group,sandblasting group,glazing group.3.There was difference between the dynamic friction coefficient of polishing group and glazing group,polishing group and sandblasting group,no difference between glazing group and sandblasting group.The ranking of the dynamic friction coefficient of three groups from the least to the most was: polishing group,sandblasting group,glazing group.4.The friction coefficient of the polishing group maintained a stable level of change,without increasing trend.The change of the friction coefficien t of the glazing group was stable at the initial stage,and turned into tempestuously inthe middle and late period.The coefficient of friction of the sandblasting group maintained a stable level,and increased slowly with time.5.The scanning electron microscopy showed that the surface of the polishing group could be seen seen with a flap hook-like wear,local microcracks,abrasive stripping and sticking.Untested area was seen some shallow scratches caused by polished.The surface of the glazing group was roughness and the abrasive surface had sharp edges,scattered many granular debris.Untested area was smooth,only a small amount of impurities attached.The surface of sandblasting group could be seen some shallow scratches,a few of debris attached,and pores was unconspicuous.Untested area surface was not smooth,there were many pores due to high pressure of sandblasting.Conclusion: Surface polishing treatment is more conducive to prevent the zirconia all-ceramic crown itself and the excessive wear of jaw natural teeth than glazing and sandblasting.Among three kinds of surface treatment,Polishing is the best surface treatment for zirconia all-ceramic crowns. |
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