Effect of coffee thermocycling on the surface roughness and stainability of denture base materials with different chemical compositions manufactured with additive and subtractive technologies.

OBJECTIVE

To evaluate the effect of coffee thermocycling (CTC) on the surface roughness (R ) and stainability of denture base materials with different chemical compositions fabricated by using additive and subtractive manufacturing.

MATERIALS AND METHODS

Disk-shaped specimens were additively (FREEPRINT denture, AM) or subtractively (G-CAM, GSM and M-PM, SM) fabricated from three pink denture base materials in different chemical compositions (n = 10). R was measured before and after polishing, while color coordinates were measured after polishing. Specimens were subjected to CTC (5000 cycles) and measurements were repeated. Color differences (ΔE ) after CTC were calculated. R among different time intervals within materials was evaluated by using repeated measures analysis of variance (ANOVA), while 1-way ANOVA was used to evaluate the R of different materials within each time interval and the ΔE values. Color coordinates within each material were compared by using paired samples t-tests (α = 0.05).

RESULTS

R before polishing was the highest for all materials (p < 0.001), while SM had its lowest R after CTC and AM had its lowest R after polishing (p ≤ 0.008). Before polishing, AM had the highest R among the materials (p < 0.001). After polishing, SM had higher R than AM (p < 0.001). After CTC, GSM had the lowest R (p ≤ 0.048). SM had the lowest (p ≤ 0.031) and AM had the highest (p < 0.001) ΔE . CTC decreased the a* and b* values of SM and AM (p ≤ 0.017), and increased the L* values of AM (p < 0.001).

CONCLUSIONS

Polishing significantly reduced the surface roughness of all materials. CTC did not increase the surface roughness of materials above the clinically acceptable threshold. Only AM had perceptible color change when previously reported threshold values for denture base materials were considered.

CLINICAL SIGNIFICANCE

Tested denture base materials may have similar surface stability after coffee thermocycling. However, subtractively manufactured denture base materials may have improved color stability when subjected to long-term coffee consumption.