Microbial Adhesion and Biofilm Formation on Denture Base Materials

Overview

Polymethylmethacrylate (PMMA) has been the material of choice for fabricating complete dentures for more than 80 years now.(1,2) As a material it is easy to handle and can be easily repaired and polished. PMMA while being a low-cost material has good esthetics. Some disadvantages of PMMA as a material are surface roughness and porosities which lead to staining, plaque accumulation and bacterial adhesion over time. Among the various factors that can influence microbial attachment to surfaces, surface roughness, hydrophilicity and free surface energy of PMMA are most important. Carboxylate and methyl ester groups found in PMMA make it a very hydrophilic material with a large amount of free surface energy. Despite the influence of the chemical composition, processing methods play the most important role in developing surface roughness.

PMMA for dentures may be processed by conventional techniques like compression moulding or injection moulding with the conventional pack and press technique being considered the 'gold standard' when it comes to processing methods as it has successfully withstood the test of time. With the advent of technology CAD/CAM milling is now being used to mill dentures from pre-polymerized blocks of acrylic resin. At the same time 3D printing/Rapid prototyping technology is also being used to print denture bases with acrylic resins. Both these technologies eliminate the need for conventional flasking and processing methods. The rapid prototyping technique involves serial apposition of resin layers on a custom designed support structure. These layers are hardened by curing with either visible light, UV Light, heat or laser depending upon the technique used. This process is repeated until the designed structure is completely formed. The milling or subtractive technique on the other hand uses pre-polymerized commercially manufactured PMMA blanks (Pucks) which are made under high pressure. This technique allows for the material to have superior mechanical properties. In reviewing the literature, no clinical studies were performed to compare which method of PMMA denture construction can reduce the amount of microbial colonization while there are a lot of invitro studies was performed.

Conditions