Abstract
Computer-aided design and Computer-aided manufacturing (CAD/CAM) has emerged as a new approach for the fabrication of removable prosthesis offering many advantages over the conventional fabrication methods. The pre-polymerized polymethyl Methacrylate (PMMA) pucks used for the fabrication of CAD/CAM removable prosthesis has a significantly enhanced physical and mechanical properties. This study aims to evaluate the effect of different salivary pH values on monomer leakage from heat-cured and CAD/CAM denture acrylic materials. Two groups of 60 discs were fabricated from heat-cured and CAD/CAM acrylic materials. These acrylic samples were subjected to mechanical brushing and thermocycling according to a standardized protocol. The discs of the two acrylic materials were immersed and incubated in three salivary solutions with different pH values (acidic, 5.7; neutral, 7; basic, 8.3) for 30 days, after which the amount of leaked monomer in the saliva solution in the two groups was determined using high-performance liquid chromatography (HPLC). Both the acrylic material type and salivary pH value had a significant effect on monomer leakage. An acidic salivary pH caused the most monomer leakage in both acrylic material groups (P < 0.05). The heat-cured acrylic material leaked less monomer than the CAD/CAM acrylic materials. The acidic salivary pH values were associated with higher amounts of monomer leakage in both heat-cured and CAD/CAM denture acrylic materials. In-laboratory immersion of newly fabricated heat-cured and CAD/CAM acrylic dentures in an acidic solution might be recommended to allow most unreacted monomers to leak before delivering the denture to the patient.