| Objective:To study the marginal and internal adaptation of two imported and two domestic CAD / CAM zirconia copings,by using the cobalt-chromium metal copings fabricated by traditional artificial wax mold lost wax casting method as a control group,compare the domestic zirconia copings with the imported zirconia copings,so as to have a preliminary understanding of the differences between the two items of marginal and internal adaptation,and provide a reference for the clinical application of CAD / CAM all-ceramic restorations.Methods: Select the left mandibular first molar on the standard super anhydrite model,prepare the super anhydrite model according to the preparation requirements of the zirconia all-ceramic crown,make 50 silicone rubber(DMG)impressions,infuse and make 50 super anhydrite molds.The molds were randomly divided into 5 groups,of which Group A was the cobalt-chromium metal copings fabricated by traditional artificial wax mold lost wax casting method,and the remaining four groups were two imported CAD / CAM zirconia copings(Group B and Group C)and two domestic CAD / CAM zirconia copings(Group D and Group E).Try the copings on after making,check them in place,shake and clean them in an ultrasonic cleaner.After cleaning,blow dry with compressed air,place the copings on the corresponding super anhydrite molds with the glass-ionomer cement,and then use the personalized base made of self-setting dental tray water and self-setting dental tray powder and the personalized cushion made of silicone rubber as fixed system.Move the entire system to a universal testing machine to maintain a 50 N vertical load for 10 minutes to make it stick,remove extra cement,and leave it at room temperature for 24 hours to make it completely stick.Then use a SYJ-150 low-speed diamond cutting machine to cut each test piece along the buccal-lingual direction parallel to the long axis of the tooth body,respectively embed it with epoxy resin on the XQ-2B metallographic specimen inlaying machine,and grind and polish the test pieces with 80 Cw,180Cw,500 Cw and 1000 Cw water sandpapers.Rinse the large particle impurities on the observation surface with running water,and then place them in an ultrasonic cleaner to shake and clean.After cleaning,blow dry for use.Place the test pieces in an ion coating instrument for vacuum gold spraying operation.Under the scanning electron microscope,magnify 50 times and 100 times to observe the thickness of the cement at the buccal margins,lingual margins,the center of the buccal surfaces and the lingual surfaces,the buccal tips the lingual tips,the center of the occlusal surface and the central fossa,and take photos.Use the image analysis software Image J to measure the OG values(Occlusal Gap),AG values(Axial Gap)、AMD values(Absolute Marginal Discrepancy)、MG values(Marginal Gap)and AOT values(Axial-occlusal transition area)of these sites.SPSS 22.0 software was used to perform a one-way analysis of variance on the measurement data(p<0.05 was considered statistically significant).Results:In the comparison of marginal adaptation,the average MG value of the copings in Group A was 45.56±8.95μm,and the average value of AMD was 97.26±8.65 μm.The average MG value of the copings in Group B was 44.07±6.96μm,and the average value of AMD was 85.56±9.13μm.The average MG value of the copings in Group C was 46.57±9.65μm,and the average value of AMD was 85.94±8.86μm.The average MG value of the copings in Group D was 43.06±9.32μm,and the average value of AMD was 95.99±9.78μm.The average MG value of the copings in Group E was 63.56±8.88μm,and the average value of AMD was 91.14±8.45μm.The average MG value of the vertical marginal gap in each group was less than 120 μm,which were all within the clinically acceptable range.There was no statistical difference in the AMD values and the MG values of the copings in each group(p>0.05).In the comparison of internal adaptation,the average AG value of the copings in Group A was 75.30±7.67μm,and the average value of OG was 60.95±5.30μm and the average value of AOT was 98.25±7.91μm.The average AG value of the copings in Group B was 64.97±9.12μm,and the average value of OG was 107.07±9.94μm and the average value of AOT was 62.26±6.54μm.The average AG value of the copings in Group C was 69.47±7.76μm,and the average value of OG was 119.58±8.84μm and the average value of AOT was 61.09±3.99μm.The average AG value of the copings in Group D was 54.45±6.91μmμm,and the average value of OG was 105.57±8.26μm and the average value of AOT was 66.63±4.15μm.The average AG value of the copings in Group E was 61.05±7.31μm,and the average value of OG was 84.70±6.36μm and the average value of AOT was 68.69±5.3μm.The average values of the internal adaptation of other groups are less than 150 μm,which are all within the clinically acceptable range.There was no statistical difference in the AG values、OG values and AOT values of the copings in each group(p> 0.05).Conclusions: In the experiment,the marginal and internal adaptation of the cobalt-chromium metal copings fabricated by traditional artificial wax mold lost wax casting method,two kinds of CAD / CAM domestic and two kinds of CAD / CAM imported zirconia base crowns were within the clinically acceptable range,and no statistical difference.The marginal and internal adaptation of domestic zirconia copings and imported zirconia copings are not significantly different.The cutting observation method is reliable for evaluating the adaptation of the restoration. |
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