Tensile and microindentation properties of maxillofacial elastomers after different disinfecting procedures

Abstract

Statement of problem: Daily disinfection of maxillofacial prosthesis may reduce their service-life and lead to replacement.

Purpose: The purpose of this study was to evaluate possible alterations in the mechanical behavior of two maxillofacial elastomers after application of four different disinfection procedures.

Material and methods: The materials tested were two maxillofacial elastomers, a commercially available polydimethylsiloxane (PDMS) and an experimental chlorinated polyethylene (CPE). Different disinfection procedures such as microwave exposure, hypochlorite solution, neutral soap and a commercially antimicrobial solution, were applied for a period which simulates one year of a real service life. Mechanical behavior was investigated through tensile and microindentation tests in various depths. Mathematical models were fitted to tensile curves. Alterations in tensile parameters (maximum stress, maximum strain, elasticity and viscoelasticity parameter) were subjected to two way ANOVA and Tukey's post hoc tests (α=.05).

Results: Most of the tensile parameters presented significant alterations among different disinfection procedures and maxillofacial materials which became also harder. Microwave exposure caused greater changes in PDMS and CPE elastomer whereas commercial antimicrobial solution and neutral soap did not significantly affect them. Microindentation and tensile tests revealed similar changes in materials' elastic modulus and hardness whereas the observed changes were greater into smaller depths.

Conclusions: Tensile and microindentation properties of PDMS and CPE elastomers presented changes after disinfected with four different procedures. Changes in the surface of both materials were more intense than in the bulk of the materials. Microwave exposure affected most the two elastomers, so concerning the findings of this study is not recommended for the disinfection of the examined PDMS and CPE elastomers. Moreover, microwave exposure and hypochlorite solution caused greater changes in the surface (3μm) of CPE samples as indicated by microindentation results. PDMS affected less from the commercial antimicrobial agent and CPE from neutral soap, which seems to be the most suitable disinfection techniques.

Keywords: Antimicrobial solution; CPE; Hypochlorite solution; Microindentation; Microwave exposure; Neutral soap; PDMS; Tensile.