This study assesses the effect of the material type (lithium disilicate, zirconia, and polymer-infiltrated ceramic) and dental bonding substrates (dentin, dentin with intra-coronal cavity, and dentin with composite filling) on the fracture resistance and failure mode of molars restored by occlusal veneers. Methods: Ninety occlusal veneers, fabricated from either lithium disilicate, zirconia, or polymer-infiltrated ceramic, were adhesively bonded to teeth prepared with either dentin, dentin with intra-coronal cavity, or dentin with composite filling. All specimens were thermally aged (5000 cycles), then load cycled (120,000 cycles). Each specimen was subjected to a compressive load through fracture, then was examined (×20) to identify the fracture type. Data were statistically analyzed. Results: Material type and dental substrate had no significant effect on the fracture resistance of adhesively retained occlusal veneer restorations. For each material, no significant differences were found between veneers bonded to dentin, dentin with intra-coronal cavity, and dentin with composite filling. Additionally, within each bonding substrate, there were no significant differences between lithium disilicate, zirconia, and polymer-infiltrated ceramic veneers. The adhesive failure was recorded mainly with zirconia occlusal veneer restorations. Conclusions: Considering the fracture results, lithium disilicate, zirconia, and polymer-infiltrated ceramic occlusal veneers perform well whatever the type of dental bonding surface. When the dental bonding surface varies, different occlusal veneer materials should be considered. Occlusal veneers bonded to dentin, dentin with composite filling, or dentin with an intra-coronal cavity exhibited a fracture resistance exceeding the average human masticatory forces in the molar area.

Background: The purpose of this in vitro study was to assess the influence of different cement systems with different ceramic primers on the retention strength of zirconia crowns. Methods: Thirty extracted molars were prepared with flat occlusal surfaces, 20 degrees taper, and 3 mm axial wall height. A zirconia crown with an occlusal bar was fabricated for each tooth. All specimens were divided (n = 10) into; Group M: Multilink Speed/Monobond N, Group P: Panavia V5/Clearfil Ceramic Primer Plus, Group D: Duo-Link universal/Z-Prime Plus. The intaglio surfaces of crowns were air-abraded using 50 µm alumina at 2.5 bar for 10 s. Then each crown was cemented onto its corresponding tooth. All specimens were thermocycled for 10,000 cycles between 5 and 55 °C. Each crown was subjected to gradually increasing vertical load along the path of insertion through hooks engaging the occlusal bar using a universal testing machine until failure. The force at dislodgment was recorded and retention strength was calculated for each specimen. The failure modes were recorded for each specimen. The data were statistically analyzed using one way ANOVA test followed by Tukey HSD test (α = .05). Results: Group D showed lowest strength (1.42 ± 0.23 MPa) and differed significantly (P < .001) from Group M (2.71 ± 0.45 MPa) and Group P (2.47 ± 0.41 MPa). There was no significant difference (P = .34) between Group M and Group P. The failure modes for Groups M and Group P were mainly cohesive, while Group D showed adhesive failure. Conclusions: The retention strength of zirconia crowns was improved with Multilink Speed and Panavia V5 cement systems, while the use of the Duo-Link Universal cement system only showed half of those retention strength values.

To evaluate the clinical and radiographic assessment of customized fusion-sputtered one-piece zirconia implants. Twenty-eight patients received either fusion sputtered one-piece zirconia implants (n = 14) or one-piece titanium implants (n = 14). All implants were one-piece designs. After 4 months of immediate loading, all implants were restored with a monolithic zirconia crown. All implants were evaluated at baseline, 6 months, 1 year, 2 years, and 5 years. Implant mobility, plaque index, and gingival index evaluations were performed. The measurements of marginal bone level were calculated radiographically. All implants were well maintained through the evaluation period with a 100% survival rate without any clinical complications. Regarding gingival index, there was no statistically significant difference (P = .364) between zirconia (3.3 ± 0.7 mm) and titanium (3.5 ± 0.6 mm) implants, after 5 years. There was no statistically significant difference (P = .470) between zirconia (1.77 ± 0.039 mm) and titanium (1.80 ± 0.28 mm) implants regarding marginal bone loss, after 5 years. One-piece fusion-sputtered zirconia implant represents a reliable treatment modality in replacing a missing tooth in the esthetic zone.

Background: Passivity of an implant-supported restoration is fundamental for its long-term survival. The aim of this study was to assess the accuracy of interface fit of screw-retained implant-supported zirconia fixed partial denture with different abutment angulations. Methods: 50 epoxy resin casts were randomly assigned into 5 groups (n=10) according to the implant placement angulations: group I; the casts received two non-tilted implants with two straight abutments, group II; the casts received a non-tilted implant with straight abutment and 17.5° tilted implant with 17.5° angled abutment, group III; the casts received a non-tilted implant with straight and 35°tilted implant with 35° angled abutment, group IV the casts received two 17.5-degree tilted implants with 17.5° angled abutments, and group V; the casts received two 35-degree tilted implants with 35° abutments. For each cast, a 3-unit zirconia fixed partial denture was fabricated. Titanium caps were bonded to corresponding zirconia fixed partial denture. For each specimen, the accuracy of fit was assessed by measuring the gap at the interface when one prosthetic screw was tightened, and when both prosthetic screws were tightened. The data were analyzed using Kruskal Wallis test followed by post-hoc dunn’s test (P<.05). Results: When the canine prosthetic screw was tightened, the median of the gab at central interface showed statistical significant difference (P=.037) between studied groups. Also, a significant difference was revealed between Group I and Group III (P=.002), Group III and Group IV (P=.026), and Group IV and V (P=.035). When central prosthetic screw was tightened, the median of the gab at canine interface showed statistical significant difference (P=.02) between studied groups. Also, there was a significant difference between Group I and Group II (P=.001), Group I and Group III (P=.02), and Group I and V (P=.04). However, there were no significant differences between studied groups when both prosthetic screws were tightened. Conclusions: The screw-retained zirconia fixed partial denture has interface fit within the clinical acceptable value regarding the precision of fit. The use of angled abutment endanger the accuracy of interface fit of screw-retained implant-supported zirconia fixed partial denture.