ABSTRACT
Objective@#Objective To evaluate the effect of repairing posterior teeth with subgingival defects with onlays after deep margin elevation and to provide a reference for clinical application.@*Methods @#Eighty-six cases of posterior teeth with subgingival defects were treated with resin filling to elevate the subgingival margin to the superior gingival margin and were then restored with onlays of cast porcelain. Patients were followed up at 1 week, 6 months and 12 months. The wear and tear of the restorations, fractures of the restorations, loss of the restorations, marginal closeness, marginal staining, secondary caries and gingival health were examined. Assessment of efficacy with reference to American public health service standards was conducted.@*Results @#One week after the operation, there was no loss of follow-up. Eighty-six cases of onlays had no prosthetic wear, prosthetic fracture, prolapse of the prosthesis, edge adhesion, edge coloration, secondary caries, etc., and the gums were healthy. At 6 months after surgery, 2 patients were lost to follow-up and 4 of the remaining 84 onlays were detached. After re-adhesion, there was no shedding. At 12 months after surgery, 5 cases were lost to follow-up and 81 cases of onlays demonstrated no further prosthetic wear, prosthetic fracture, prolapse of the prosthesis, edge adhesion, edge coloration, secondary caries, etc., and the gums were healthy. The success rate after 12 months of repair was 95.1% (77/81).Conclusion For posterior teeth with a subgingival defect, onlays of cast porcelain have the advantages of a high success rate, co@*Conclusion@# For posterior teeth with a subgingival defect, onlays of cast porcelain have the advantages of a high success rate, convenient clinical operation and no influence on periodontal health to restore posterior teeth after deep margin elevation.
ABSTRACT
OBJECTIVE@#To investigate the influence of cuspal-coverage thickness on the stress distribution of all-ceramic onlay-restored premolars by using 3D finite element (FE) analysis and to provide references for the design of all-ceramic onlays for clinical application.@*METHODS@#3D FE models of all-ceramic onlays with three cuspal-coverage thicknesses (2, 3, and 4 mm) of endodontically treated maxillary premolar were constructed based on micro-CT images. Stress distributions in the onlay, adhesive resin cement layer, and dentin of models were analyzed under vertical load (600 N) and oblique load (200 N).@*RESULTS@#When the cuspal-coverage thickness increased, the peak maximum principal stress value decreased inside the onlay but increased in the margin of the adhesive resin cement layer. In addition, stress concentration areas increased in the coronal residual dentin on the palatal side under oblique load.@*CONCLUSIONS@#An increase in the cuspal-coverage thickness of all-ceramic onlays may reduce the risk of rupture of the restoration but may deteriorate the restoration and cause palatal dentin fracture.