Systematic review and meta-analysis of welding procedures in one-piece cast implant-supported frameworks.

Jéssica Marcela De Luna Gomes,Ronaldo Silva Cruz,Sandra Lúcia Dantas De Moraes,Hiskell Francine Fernandes E Oliveira,Cleidiel Aparecido Araujo Lemos,Eduardo Piza Pellizzer

doi:10.1590/1807-3107bor-2019.vol33.0110

Jéssica Marcela De Luna Gomes, Ronaldo Silva Cruz + Show 4 more

Open Access

https://doi.org/10.1590/1807-3107bor-2019.vol33.0110

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Abstract

The objective of this systematic review and meta-analysis was to evaluate the effect of welding techniques on implant-supported prostheses and determine whether they contribute to a better adaptation compared with a one-piece cast. A search was conducted using the PubMed/MEDLINE, Embase, and Cochrane Library databases, and articles published until November 2017 were obtained from these databases. This review followed the PRISMA criteria and is registered on the PROSPERO platform (CRD42017081865). The PICO question was "Do welding procedures in one-piece cast implant-supported frameworks influence implant/abutment-framework marginal misfits?" Eleven studies were selected for a qualitative analysis, and seven studies were selected for a quantitative analysis. A total of 189 specimens were fabricated using different materials (cp-Ti, Ni-Cr, Cr-Co, and noble alloys), and welding techniques such as laser welding, conventional welding, tungsten inert gas, and brazing were applied. A vertical marginal misfit was measured using an optical microscope, a stereomicroscope, and/or a scanning electron microscopy. The qualitative analysis in the studies demonstrated a positive effect of the welding techniques on the adaptation of the infrastructures. The meta-analysis confirmed the results (p < 0.00001; MD: -36.14; 95%CI: -48.69 to -23.59). Within the limitations of this study and regarding the heterogeneity of the samples, we conclude that the soldering point technique is effective for obtaining relatively low values of marginal misfit, with laser welding as the most effective technique. However, additional studies were recommended due to the heterogeneity of different variables (alloys, connection, and misfit evaluation) in the included studies.

Highlights

The accuracy of fitting between a prosthesis and an implant is a prerequisite for the long-term success of implant-supported rehabilitations.[1]
In relation to the quantitative analysis, a relatively low value of marginal misfit for groups was observed with the welding technique compared with the one-piece cast technique (p < 0.00001; mean difference (MD): -36.14; 95%confidence interval (CI): -48.69 to -23.59) (Figure 2)
The results showed that the welding of the cp Ti structures is able to lower the levels of misfit and to improve the passivity levels for the same frameworks when compared to one-piece cast frameworks

Summary

Introduction

The accuracy of fitting between a prosthesis and an implant is a prerequisite for the long-term success of implant-supported rehabilitations.[1] Misfits formed at the interface between the implant and the infrastructure transfer stresses to the prosthesis and the peri-implant bone, with consequent adverse biological responses and prosthetic complications.[2,3]. Several fabrication methods of implant frameworks are proposed to minimize distortion, and they reduce the marginal misfit.[4]. Studies affirm that distortion is inevitable during the fabrication process of frameworks (stone cast, inclusion in coating material, and casting in metallic alloy) since it is inherent to the process.[5,6,7] New technologies, such as CAD/CAM systems, demonstrate substantial accuracy of the pieces that constitute the infrastructures in a one-piece cast,[8,9] and certain manufacturing stages are omitted compared with the conventional technique of lost-wax.[3]

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