Randomized Clinical Trial of Implant‐Supported Ceramic–Ceramic and Metal–Ceramic Fixed Dental Prostheses: Preliminary Results

Abstract

Purpose The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52–75 years) were recruited for the study to receive a 3-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. Material: ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Results Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher’s exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure (p = 0.68), and connector height (p = 0.91). Conclusions Although there were no significant associations between connector height, curvature of gingival embrasure, core/veneer thickness ratio, and material system and the survival probability of implant-supported FDPs with zirconia as a core material, the small number of fractures precludes a definitive conclusion on the dominant controlling factor.

Randomized Controlled Clinical Trial to Compare Posterior Implant‐Supported Modified Monolithic Zirconia and Metal‐Ceramic Single Crowns: One‐Year Results

“…Increased complication rates of ceramic fracture has been reported in previous studies with metal‐ceramic implant‐supported FDPs, especially in screw‐retained FDPs . Compared with metal‐ceramic FDPs, zirconia‐based implant‐supported FDPs have also been reported to have a high fracture rate of the veneering porcelain . Regarding the MMZ group, the technical complication rate was 2.9% in this study.…”

“…Implant‐supported zirconia‐based FDPs have been reported to have high survival rates, indicating that the fracture resistance of zirconia frameworks was high enough to withstand general occlusal loading . One randomized clinical trial (RCT) with posterior implant‐supported metal‐ceramic vs. zirconia‐based FDPs reported outcomes with survival rates above 90% . However, high fracture rates of veneering porcelain ranging from 6.5% to 90% have also been observed with implant‐supported, zirconia‐based FDPs for partially and completely edentulous patients .…”

A systematic review and meta‐analysis of 3‐unit fixed dental prostheses: Are the results of 2 abutment implants comparable to the results of 2 abutment teeth?

“…Of the 66 publications included for analysis, 24 articles reported on a total of 765 implant‐supported 3‐unit FDP distributed over 27 groups of patients (Tables ) …”

Fracture behavior of single-structure fiber-reinforced composite restorations

“…[19] According to the visual inspection following the fracture test, the cracks in the crown restorations made of PFC and dental ceramics (Emp, XTE, and eMx groups) originated at a similar point, near the flat surface of the incisor edge area. This result may indicate that the fracture load was evenly applied on the flat surface of all of the experimental crown restorations.…”