Three-dimensional finite element analysis of removable partial denture with periodontally compromised abutments / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate three-dimensional (3D) finite element (FE) modeling of different periodontally compromised unilateral distal extension removable partial denture (RPD) abutments using the data of a 3D non-contact digitizing scanner.</p><p><b>METHODS</b>FE models were established, and the following structures were simulated in the models: alveolar bone, mucosa, abutments, periodontal ligaments, framework and artificial teeth. The alveolar bone and periodontal ligaments around the distal abutment in the three models were designed as normal, with bone defect and with periodontal ligaments defect respectively.Vertical or buccally inclined forces of 50, 100, 100 N were applied on the artificial teeth of the RPD and the stress distributions on the supporting tissues were calculated.</p><p><b>RESULTS</b>Under vertical loading, the maximal stress on the alveolar bone of the abutment were as follows: periodontal ligaments defect model (3.57 MPa) > bone defect model (3.21 MPa) > normal model (2.63 MPa). Under buccally inclined loading, the maximal stress on the alveolar bone of the abutment were as follows: periodontal ligaments defect model (2.50 MPa) > bone defect model (2.41 MPa) > normal model (1.79 MPa). Under buccally inclined loading, the stresses on distal aspects of the residual alveolar ridge were higher than that of the vertical loading model.</p><p><b>CONCLUSIONS</b>3D non-contact digitalizing scanner was useful for the finite element modeling process of removable partial denture.</p>

Effects of try-in paste and luting agent on the resultant color of all-ceramic veneers / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purposes of this study was to investigate the effects of luting agents on the resultant color of IPS e.max all-ceramic veneer restorations, and to evaluate the similarity of try-in pastes and the corresponding luting agents on the final color.</p><p><b>METHODS</b>Disc-shaped ceramic specimens were fabricated and seated on four shades of resin specimens to mimic the complex of ceramic veneer laying on tooth substrates. Try-in pastes and luting agents (Shades of TR, B0.5, A1, A3, W0) were applied into the inter-layer of ceramic and resin specimens, respectively. The color of the combinations was measured using a spectrophotometer and subsequently converted to CIE L*a*b* values. Color changes after luting agent applied, and between try-in paste and corresponding luting agent were calculated and registered as DeltaEresin and DeltaEpaste-resin.</p><p><b>RESULTS</b>DeltaEresin value of A2, A3 backgrounds was more than 1.0. DeltaEresin value of A4, A5 backgrounds was less than 1.0. The DeltaEpaste-resin value of A3 backgrounds was more than 1.0, whereas, A2 was less than 1.0 (except for shade W0). The DeltaEpaste-resin value of shade W0 was significantly different from other shades of luting agents.</p><p><b>CONCLUSION</b>The color of ceramic veneer restorations were affected by luting agents with A2, and A3 background colors. The agreement of the try-in paste and the corresponding luting agent was excellent for A2 background (except for W0).</p>