Monolithic Lithium Disilicate Full-Contour Crowns Bonded on CAD/CAM Zirconia Complete-Arch Implant Bridges With 3 to 5 Years of Follow-Up
This study was carried on to assess the clinical performance of a novel restorative concept consisting in single monolithic lithium disilicate full-contour crowns bonded on computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia complete-arch implant bridges, to overcome the drawbacks related to the chipping of porcelain fused to zirconia restorations. Sixteen patients received 18 implant-supported hybrid screw-cement-retained complete-arch restorations, consisting of single monolithic lithium disilicate full-contour crowns bonded on CAD/CAM zirconia frameworks. The restorations were supported by 4–8 implants. All patients were followed up for at least 3 years on function (range 36 to 60 months, mean 49.3 months). Clinical controls were scheduled every 4 months. The outcomes were implant and prosthetic survival and success rates, any complications, patient satisfaction, and soft tissue parameters. No dropouts occurred. The overall implant and prosthesis survival rates were 100%. One of 18 restorations (1 of 236 dental units) showed a chip-off fracture of the veneering ceramic that was polished intraorally without any additional treatment, scoring a cumulative prosthetic success rate of 100%, according to the California Dental Association index. All patients were functionally and esthetically highly satisfied with their restorations. Successful soft tissue parameters were found around all implants. Single monolithic lithium disilicate full-contour crowns, bonded on CAD/CAM screw-retained complete-arch zirconia frameworks, showed favorable preliminary outcomes with medium-term follow-up. However, randomized controlled studies of this technique are required for further conclusive recommendations.
Figure 1. Radiographic acrylic resin templates without any vestibular prosthetic flanges, to assess the prosthetic emergence profile according to the smile line of the patient. Figure 2. The CAD design of the zirconia frameworks, customized to accommodate the single lithium disilicate full-contour crowns and to ensure the minimum thickness of the connectors recommended by the manufacturer: (a) in the upper jaws and (b) in the lower jaws. Figure 3. The single lithium disilicate full-contour crowns waxed up onto the zirconia framework. Figure 4. The lithium disilicate full-contour crowns, not involving the screw access holes of the zirconium dioxide framework, were cemented in the laboratory, and the remaining crowns were placed directly into the mouth after having screwed the restoration.
Figure 5. (a) Occlusal view of monolithic lithium disilicate full-contour crowns bonded on a CAD/CAM zirconia complete-arch implant bridge in the upper jaw. (b) Postinsertion panoramic radiograph, verifying accurate fit of the definitive restoration. Figure 6. (a) The clinical and (b) radiographic outcomes at the 5-year follow-up.
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