The Effect Of PFM Crown Venting On The Residual Cement Of Cement-Retained Implant Denture .A Clinical Study

Objective:To observe the effect of the vent of PFM crown on the residual cement of the cement-retained implant restorations,.so as to provide some basis for the clinical application of how to reduce the residual cement.Method:From January 2018 to January 2019,15 patients in the second department of stomatology of jiangxi provincial people's hospital were selected for the upper restoration of single posterior tooth implantation.The same patient repaired 2 cobalt-chromium PFM crowns with venting on the occlusion surface and the same repair abutment.In the experimental group,the PFM crown venting was opened,the PFM crown venting was closed in the control group,the GIC I was routinely bonded.Then remove the bonding material of the vent and the screw hole,and remove the upper structure for evaluation.After removal of the restoration,a photograph of the implant and surrounding tissues was taken perpendicularly using an intraoralocclusal dental mirror for evaluation of cement remnant in the tissue,All four quadrants(mesial,distal,labial,and lingual)of the crown were photographed using a specially constructed device to fix between the photo camera and the restoration.The images were imported and analyzed using Adobe Photoshop.To calculate the area covered with cement remnants,the pen tool " and make path" options were used.The total surface area was marked and the number of pixels was recorded from the histogram option,the same was applied to the area covered with cement remnants.The ratio between the area covered with cement and the total surface area of the crown was calculated.Next,the perpendicularly taken photograph of occlusal view of the implant and surrounding tissues was evaluated.after the evaluation,the cement of crown were removed and polished.SPSS22.0 statistical software was used to analyze and process the data.P<0.05 was considered statistically significant.Results:1 Experimental goup,PFM crown residual cenment area/PFM crown area = 0.0632±0.0037,residual cement on soft tissue/soft tissue area = 0.0319±0.0070.2 Control goup,PFM crown residual cenment area/PFM crown area = 0.1080±0.0147,residual cement on soft tissue/soft tissue area = 0.0562±0.0106.3 SPSS 22.0 software analysis showed that the adhesive residual rate in the experimental group was significantly lower than that in the control group(P < 0.05),and the differences between the groups were statistically significant.The residual rate of soft tissue adhesive in the mouth of the experimental group was significantly lower than that of the control group(p < 0.05),and the difference between the groups was statistically significant.Conclusion: The PFM crown venting can reduce the residual cement effectively.