Mechanical and optical properties of machined, printed, and conventional dental polymers

OBJECTIVE: This study aims to compare the flexural strength and color stability of conventional, machined, and printed dental polymers. Secondarily, the effects of aging, fatigue, coffee, distilled water, and UV light on the color stability and flexural strength of the different dental polymers will be evaluated. MATERIALS AND METHODS: Sixty disks 14mm in diameter and 2mm in thickness were fabricated from each of the following polymers: Jet Tooth Shade (Lang Dental), ProTemp (3M-ESPE), Telio CAD Temp (Ivoclar Vivadent), Vita CAD Temp (Vita), Temporary CB (FormLab), Dentca (Dentca), and Bego VarseoSmile Crown Plus (Bego). The sixty disks from each polymer were then divided into the six following groups: no treatment, thermocycling, fatigue, thermocycling and coffee, distilled water and finally UV Light. Prior to any treatment, the color coordinates CIE L*a*b*, were registered first. The non-treated groups were fractured using the Instron Universal Testing Machine to obtain flexural strength values. Thermocycling consisted of placing the specimens in 30 seconds 5°C water and then 30 seconds in 55°C water for 5,000 cycles. Fatigue testing consisted of cyclic loading the disk specimens by calculating 60% of the mean load to failure from the non-treated group and subjecting them to 50,000 cycles. The third group was placed under thermocycling for 1,500 cycles and then placed in coffee for 15 days. Another group was placed in distilled water for 15 days. Finally, the UV light treatment consisted of exposing the disk specimens to UV light for ten hours over the course of five days. After treatment, the color coordinates were recorded again and fractured using the Instron Universal Testing Machine. The data was analyzed for any statistically significant differences using ANOVA with a<0.05. RESULTS: The flexural strength values were highest for Telio CAD Temp, that was affected only by UV light via a statistical analysis. ProTemp was second highest followed by Bego VarseoSmile Crown Plus, Dentca, Temporary CB, Vita ...