Framework Fracture of Zirconia Supported Full Arch Implant Rehabilitation: A Retrospective Evaluation of Cantilever Length and Distal Cross‐Sectional Connection Area in 140 Patients Over an Up‐To‐7 Year Follow‐Up Period

Abstract

Purpose:To evaluate the relationship between different dimensional parameters in implant-supported monolithic zirconia fixed complete dental prostheses (IFCDPs) and the incidence of framework fracture in a large sample of cases in vivo. Materials and Methods:This retrospective observational study evaluated all patients rehabilitated with screw-retained zirconia IFCDPs between January 2013 and April 2019 at a private practice. The minimum follow-up period was 1 year after occlusal loading. Fractures were classified as: type I-fractures that happened between but not involving the two most posterior screw-access openings (SAOs) and type IIfractures of the distal cantilever. Cantilever length, distal connector cross-sectional area, and screw access opening length were measured using data obtained from digital scans. Logistic regression was performed to evaluate the relationship between types I and II fractures and the independent variables (dimensional parameters). Using the receiver operating characteristic curves, two parameters were identified to be useful for establishing a cut-off and predicting type II fractures. Results: A total of 180 prostheses delivered to 140 patients were analyzed. Five implants failed in three patients: three before delivery of the definitive prostheses and two after. Ten prostheses failed (5.6% prosthetic failure rate): 2 because of implant failures, and 8 because of framework fractures. Five fractures were classified as type I and three as type II. Significant associations were found between cantilever length and type I fractures (Wald = 5.772, df = 1, p = 0.016), distal connector cross-sectional area and type II fractures (Wald = 3.806, df = 1, p = 0.051), and cantilever length and the total number of fractures (Wald = 6.117, df = 1, p = 0.013). Conclusion: Zirconia IFCDPs may be reliable medium-term solutions if some dimensional parameters are followed. The ratios between the cantilever length and cross-sectional connector area should be <0.51, while the ratio between the cantilever length and screw access opening length should be <1.48.

Fracture Resistance of CAD/CAM Implant-Supported 3Y-TZP-Zirconia Cantilevers: An In Vitro Study

“…Tirone et al reported on the CL or the thickness of the zirconia around the screw access opening (SAO) to the fracture of the structure [ 29 ], and their results were in line with those found in our study, because the SAO was the zone where there was a fracture in the zirconia structures. In order to overcome this problem, Alshiddi et al used a thickness increase of 0.5 mm around the distal SAO in order to reinforce it [ 9 ].…”

“…With regard to CL, the results obtained in this study corroborate what is described by several authors [ 2 , 9 , 29 ]. Bearing in mind that the ideal cantilever length should not exceed 9 mm, in this study, structures with 6 mm and 10 mm cantilevers were tested in order to test their resistance to fracture.…”

Prosthetic complications with monolithic or micro‐veneered implant‐supported zirconia single‐unit, multiple‐unit, and complete‐arch prostheses on titanium base abutments: A single center retrospective study with mean follow‐up period of 72.35 months

“…In addition, the difference in follow‐up periods between the present study and Diéguez‐Pereira and colleagues' 10 study may explain the variations in prevalence for complications. Previous studies on clinical success of complete‐arch implant‐supported zirconia prostheses were limited to 7 years of follow‐up 33,35–38 …”

“…Even though there are retrospective reports on implant‐supported zirconia prostheses, 3,8–10,28–38 the type of prosthetic complication that may be encountered depending on the prosthetic design is not clear, the design being a single‐unit, multi‐unit, or a complete‐arch fixed prosthesis. Clinicians can benefit from a long‐term retrospective study on clinical performance of implant‐supported zirconia prostheses with ti‐base abutments, focusing on the effect of prosthetic design.…”

“…27 However, considering high esthetic expectations of patients and clinicians, micro veneering of nonfunctional areas of zirconia prostheses is still common, particularly for those situations in the maxillary anterior region. 10 Even though there are retrospective reports on implantsupported zirconia prostheses, 3,[8][9][10][28][29][30][31][32][33][34][35][36][37][38] the type of prosthetic complication that may be encountered depending on the prosthetic design is not clear, the design being a single-unit, multi-unit, or a completearch fixed prosthesis. Clinicians can benefit from a long-term retrospective study on clinical performance of implant-supported zirconia prostheses with ti-base abutments, focusing on the effect of prosthetic design.…”