Comparison of Mechanical Properties of PMMA Disks for Digitally Designed Dentures.

Tamaki Hada,Awutsadaporn Katheng,Manabu Kanazawa,Shunsuke Minakuchi,Maiko Iwaki

doi:10.3390/polym13111745

Abstract

In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer’s recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials (p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

Highlights

Poly(methyl methacrylate) (PMMA) has conventionally been the most common and the is oldest material used for fabricating complete dentures, owing to its advantages, such as excellent dimensional stability in oral environments, low cost, light weight, acceptable aesthetics, and the ease of fabrication and repair [1,2]
There are many concerns related to the use of PMMA, including denture fracture caused by water sorption and impact, as well as the decrease in flexural strength, porosity, and polymerization shrinkage [3,4,5]
Al-Dwairi et al [17] investigated the mechanical properties, including the flexural strength, flexural modulus, and impact strength of PMMA-disks, and they were significantly higher than those of a conventional heat-polymerizing resin (Conventional PMMA); these results indicate the durability of PMMA-disks

Summary

Introduction

Poly(methyl methacrylate) (PMMA) has conventionally been the most common and the is oldest material used for fabricating complete dentures, owing to its advantages, such as excellent dimensional stability in oral environments, low cost, light weight, acceptable aesthetics, and the ease of fabrication and repair [1,2]. To solve the abovementioned problems, Soeda et al [20] manufactured a frame into which ready-made artificial teeth could be arranged in advance with a 3D printer; a commercially available self-polymerizing resin can be poured, and the frame can be used to develop a method for creating custom disks for CAD/CAM. A frame called the dedicated tray for the denture cutting time reduction kit (CA-DK1-TR; DGSHAPE, Hamamatsu, Japan), which is shown in Figure 1b [21], is commercially available This frame cuts a tooth mold for fitting artificial teeth into a tray. As shown, a commercially available silicone frame time reduction kit for cast denture bases (CA-DK1; DGSHAPE, Hamamatsu, Japan) is made to self-polymerize resin into a block.

Three-Point Bending Test

Staining Test

Statistical Analysis

Results

DDiiscussion

Conclusions