The Fracture Resistance of Additively Manufactured Monolithic Zirconia vs. Bi-Layered Alumina Toughened Zirconia Crowns When Cemented to Zirconia Abutments. Evaluating the Potential of 3D Printing of Ceramic Crowns: An In Vitro Study.

Amirali Zandinejad,Dean Morton,Marta Revilla-León,Mohammad Mujtaba Methani,Leila Nasiry Khanlar

doi:10.3390/dj9100115

Abstract

(1) Background: This study compared the fracture resistance of additively manufactured monolithic zirconia and bi-layered alumina toughened zirconia crowns on implants. (2) Methods: Maxillary model with a dental implant replacing right second bicuspid was obtained. Custom abutments and full-contour crowns for additively manufactured monolithic zirconia and bi-layered alumina reinforced zirconia crowns (n = 10) were fabricated. The crowns were cemented to implant-supported zirconia abutments and the assembly fixed onto resin blocks. Fracture resistance was measured using a universal testing machine at a crosshead speed of 2 mm/min. A Kruskal–Wallis test was used to analyze the data. (3) Results: Although additively manufactured monolithic zirconia crowns demonstrated a higher mean fracture resistance than bi-layered alumina toughened zirconia crowns, statistical analysis revealed no significant difference in fracture resistance between the two groups. All specimens fractured at the implant–abutment interface. (4) Conclusions: Additively manufactured bi-layered alumina toughened zirconia crowns demonstrated similar fracture resistance to additively manufactured monolithic zirconia crowns when cemented to implant-supported zirconia abutments.

Highlights

Due to their optical properties, ceramics have long been used to mimic the appearance of natural teeth in dental restorations [1]
Samples in both groups fractured at the abutment level near the interface of zirconia abutment and implant analog with no significant differences between two groups (Figure 7)
The bi-layered ceramic restorations were expected to demonstrate higher values for fracture resistance, owing to their tendency to mimic the structure of human enamel and dentin

Summary

Introduction

Due to their optical properties, ceramics have long been used to mimic the appearance of natural teeth in dental restorations [1]. Even though all ceramic restorations impart a phenomenal combination of biocompatibility and esthetics, different studies have demonstrated their higher incidence of fracture when compared to conventional metal–ceramic prostheses. Their higher tendency to develop fractures could be related to their brittleness [4,5]. Increasing demands for esthetic dentistry and tooth color restorations have led to utilizing ceramics in implant dentistry mostly for replacing missing teeth in the esthetic zone [6,7]. Ceramic abutments were developed to optimize the esthetic outcome in the esthetic zone with respect to final color of the restoration and soft tissue surrounding the crown [8,9,10]. All ceramic crowns, especially when supported by implants, will be more prone to fracture under occlusal forces [11,12]

Objectives

Methods

Results

Discussion

Conclusion