Long-term microwaving of denture base materials: effects on dimensional, color and translucency stability

Abstract

While the combined effect of microwave irradiation with cleansing solutions on denture base materials has been investigated, the effects of only using microwave irradiation and, more importantly, in a long-term basis, was not studied yet. Objective The purpose of this study was to evaluate the effect of a long-term repeated microwaving on the dimensional, color and translucency stability of acrylic and polyamide denture base materials.Material and Methods Thirty two specimens (32 mm x 10 mm x 2.5 mm) from polyamide (Valplast) and PMMA (Vertex Rapid Simplified) denture base materials were made. Eight specimens from each material were immersed in distilled water (control) and 8 were subjected to microwave exposure at 450 W for 3 minutes for a period simulating 224 days of daily disinfection. Linear dimension, color change (ΔE*) and translucency parameter (TP) were measured at baseline and after certain intervals up to 224 cycles of immersion, using a digital calliper and a portable colorimeter. The results were analysed using two-way repeated measures ANOVA to estimate possible differences among predetermined cycles and material type. Regression analysis was also performed to estimate the trend of changes with time. Statistical evaluations performed at a significance level of 5%.Results Data analysis showed significant changes in length at baseline with an increasing number of cycles (p<0.05) and a significant interaction of cycle-material (p<0.001). The ΔΕ* parameter was significantly higher with a higher number of cycles (p<0.001), but it did not vary between materials (p>0.05). TP decreased similarly in both materials following microwave action but in a significantly higher level for Valplast (p<0.001).Conclusions The results indicated that long-term repeated microwaving affects linear dimensional, color and translucency changes of both materials. Differences between PMMA and polyamide material were noted only in dimension and translucency changes.

Evaluation and Comparison of the Influence of Microwave as a Disinfectant Method on the Colour Stability, Mechanical and Physical Properties of Thermoplastic (Breflex) and Acrylic Resins Denture Base Material

“…A recent study was performed by Polychronakis N et al ( 2018) (33) , to assessed the Influence of a long-term of repeated microwave (450 W for 3 minutes daily disinfection for 224 days) on the stability of color, translucency and dimension of thermoplastic (Valplast) and (Vertex Rapid Simplified) PMMA resins denture base materials.…”

Fibrin Biopolymer Incorporated with Antimicrobial Agents: A Proposal for Coating Denture Bases

“…Besides reinforcing oral hygiene, DS treatment usually involves the administration of local and systemic antifungals [ 2 , 19 , 20 ]. However, these approaches may have certain setbacks such as local and systemic side effects, and antifungal resistance, which can lead to a disease recurrence [ 2 , 20 ].…”

“…Besides reinforcing oral hygiene, DS treatment usually involves the administration of local and systemic antifungals [ 2 , 19 , 20 ]. However, these approaches may have certain setbacks such as local and systemic side effects, and antifungal resistance, which can lead to a disease recurrence [ 2 , 20 ]. Denture cleansers and oral mouth rinses are also used as antimicrobial agents; for the management and control of DS, however, their effectiveness depends directly on their continuous and proper use, following the manufacturer’s recommendations on the preparation and immersion period [ 21 , 22 , 23 ].…”

Measurements of surface scale changes in different denture base materials by stereophotogrammetric technique

“… 8 , 9 The dimensional stability of dentures during processing and in service is critical for denture fit and patient satisfaction. 10 Further developments in denture base materials and polymerization methods have led to the marketing of new types of resins: high-impact resins, rapid-cured acrylics, light-activated resins, and resins specially designed for microwave curing. 11 - 13 The dimensional stability of denture base materials has been extensively studied by estimating the changes occurring across the vertical, horizontal, and sagittal planes using various measurement methods.…”