Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region.

Guerino Paolantoni,Gaetano Marenzi,Gilberto Sammartino,Jolanda Mignogna,Andrea Blasi

doi:10.1155/2016/8767845

Abstract

The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces); in 45 cases the restoration was a screw-retained restoration (one piece). Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

Highlights

The clinical advantages of ceramic abutment led to a development of their use in implant-supported restorations [1]
Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment
At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the Plaque Index (PI), Bleeding Index (BI), and marginal bone loss (MBL)

Summary

Introduction

The clinical advantages of ceramic abutment led to a development of their use in implant-supported restorations [1]. Zirconia (ZrO2) has probably been the most widely studied material in the last twenty years following the discovery of the stress-assisted tetragonal-to-monoclinic transformation in partially stabilized zirconia alloys [2]. This phase transformation, usually referred to as martensitic transformation, is accompanied by a 3–5% volume expansion, which helps to arrest (or at least to minimize) the propagation of cracks [2]. A customized zirconia abutment can accommodate a nonideal implant position while simultaneously supporting the morphological features of the soft tissues and overlying restoration [6]

Methods

Results

Conclusion