Reinforcement of poly(methyl methacrylate) denture base with glass flake.

OBJECTIVES: Since the introduction of poly(methyl methacrylate) as a denture base material, it has suffered from having relatively poor mechanical properties. Many methods of improving its strength and toughness have been investigated. Most of these have not been adopted due to: increased cost, the need for specialist processing equipment or increased laboratory time due to more complicated procedures. Glass flake has been used as a reinforcing agent in many industrial polymers, but is as yet untested with denture base acrylic materials. The aim of this study is to evaluate the effect of adding glass flake to denture base acrylic powder on the fracture toughness of the set material.
METHODS: Glass flake was added in 5, 10 or 20% w/w to Trevalon denture base powder. The material was mixed, flasked, packed and processed in a manner typical for a denture base material. Fracture toughness was determined using a double torsion test technique.
RESULTS: The addition of glass flake gave up to a 69% increase in fracture toughness compared to plain Trevalon material. The addition of 5% glass flake lead to an improvement in fracture toughness that was statistically significant compared to both plain Trevalon and the 10 and 20% groups. SIGNIFICANCE: The significant improvement in fracture toughness of a denture base acrylic material using glass flake is an extremely promising result. Other mechanical properties will require testing before glass flake can be recommended as a reinforcing agent for denture base acrylic materials.