Comparative Analysis of Static and Viscoelastic Mechanical Behavior of Different Luting Material Categories after Aging.

Nicoleta Ilie

doi:10.3390/ma14061452

Abstract

The longevity of indirect restorations is primarily determined by the appropriate selection of the luting material. The function of a luting material is to seal the restoration and hold it in place for the time required for service. The mechanical behavior of luting materials and in particular their aging behavior, therefore, play a decisive role. The study provides a comparative analysis of the static and dynamic mechanical behavior of the most commonly used luting material categories—zinc phosphate cement, glass–ionomer cement, resin-modified glass–ionomer cement, resin-based composites, and self-adhesive resin-based composites—and their aging behavior. It also takes into account that luting materials are viscoelastic materials, i.e., materials that respond to external loading in a way that lies between an elastic solid and a viscous liquid. Flexural strength and modulus were determined in a three-point bending test followed by fractography analysis. The quasi-static and viscoelastic behavior was analyzed by a depth-sensing indentation test provided with a dynamic mechanical analysis (DMA) module at 20 different frequencies (1–50 Hz). The fracture toughness was evaluated in a notchless triangular prism (NTP) test. Material type exhibits the strongest influence on all measured properties, while the effect of aging becomes more evident in the material reliability. The variation of the viscoelastic parameters with aging reflects cement maturation or polymer plasticization.

Highlights

Important selection criteria encompass the material used for the inrestoration, the ability of the luting material to create a stable connection between the restoration and the tooth/implant abutment, the mechanical behavior of the luting direct restoration, the ability of the luting material to create a stable connection between the restoration and the tooth/implant abutment, the mechanical behavior of the luting materials, and even their color and translucency [1]
The present study has focused on one, albeit a very complex aspect within these selection criteria, namely, the mechanical behavior
The study takes into account that luting materials are viscoelastic materials, i.e., materials that react to external forces in a way that lies between the behavior of an elastic solid and a viscous liquid and must be analyzed [18]

Summary

Introduction

In addition to the functions of establishing a connection between restoration and tooth/abutment and not harm the tooth or tissue [2], luting materials have to withstand in the oral cavity high mechanical loads, fatigue, and chemical and enzymatic attacks. These complex tasks require high standards in the selection of a suitable luting material [1] and have led to the use of material categories that differ in their chemical composition [2,3], setting reaction, and physical and mechanical properties [1,4]

Objectives

Methods

Results

Discussion

Conclusion