Color stability of lithium disilicate ceramics after aging and immersion in common beverages.

STATEMENT OF PROBLEM: The color of an esthetic restoration and its color stability are important for long-term success. However, the impact of common beverages on lithium disilicate ceramic is not well known. PURPOSE: The purpose of this in vitro study was to investigate color variations of lithium disilicate ceramics after thermocycling (TC) and immersion in commonly consumed beverages. MATERIAL AND METHODS: A total of 288 specimens (1×10×10 mm) were fabricated from IPS e-max computer-aided design (CAD) (n=72), IPS e-max CERAM ([CER] n=72), IPS e-max Press with glazing ([PG] n=72), and IPS e-max Press without glazing ([PNG] n=72) according to the manufacturer's instructions. Each group was divided into 4 subgroups (n=18): TC, coffee, black tea, and red wine. Thermocycling was performed at 21 900 cycles at 5°C, 37°C, 55°C, and 37°C (3 years' clinical simulation), whereas the specimens were soaked in the staining solutions for up to 54 hours (3 years' clinical simulation). Color parameters L*, a*, and b* were assessed with an ultraviolet-visible spectroscopy recording spectrophotometer. Color difference (ΔE) was calculated using the equation [ΔΕ= [(ΔL*)2 + (Δa*)2 + (Δb*)2]½]. Intraexaminer reliability was assessed by using the intraclass correlation coefficient. Two-way analysis of variance was used for the analysis of ΔΕ, and the parameters L*, a*, and b* were analyzed with linear mixed models for repeated measurements and the Bonferroni pair-wise comparison test (α=.05). RESULTS: Parameters ΔΕ, L*, a*, and b* were significantly affected by the interaction between material and treatment (P<.001). A ΔΕ >1 was recorded for PG with tea, wine, and coffee, PG after TC and CER after TC. For L*, greater reduction was observed for PNG with tea and CER after TC, whereas for a* significant changes were positive (to red shades), except for PNG with TC, where PNG with wine showed the greatest positive change. For b*, significant changes were negative (to blue shades) except for PNG with tea and coffee and CAD with tea. CONCLUSIONS: All groups demonstrated color changes below the clinically perceptible level (ΔΕ<3.7), except PNG in tea which showed statistically significant color differences (ΔΕ>4). CAD presented higher color stability compared with the nonglazed Press specimens.

Soft denture liners' effect on the masticatory function in patients wearing complete dentures: A systematic review.

OBJECTIVES: To explore the effect of soft denture liners on the masticatory performance and muscle activity of edentulous patients wearing complete dentures, as determined by using objective measurement methods. DATA: Randomized controlled clinical trials and Cross-over studies that evaluated the masticatory capacity and muscle activity in denture wearers with and without soft denture liners were included in this systematic review. SOURCES: A comprehensive literature search was performed via electronic databases using the appropriate key words. The last search took place in September 2014. STUDY SELECTION: The potentially appropriate articles were identified and evaluated for eligibility through a predefined review process conducted by two examiners. Six out of the 176 identified records were included for quality and systematic assessment. CONCLUSIONS: The observed clinical and methodological diversity determined the narrative approach for the pooling of the findings. According to the studies brought together for the current systematic review, soft denture liners provided denture wearers with increased masticatory function compared to conventional denture base materials. Specifically, the use of long-term silicone liners significantly improved the mastication parameters. The observed intervention effects suggest further studies of higher quality to allow reliable conclusions to be drawn and to strengthen the clinical significance of these materials to patient's functionality. CLINICAL SIGNIFICANCE: Soft denture lining materials have been suggested to address functional problems arising during complete denture function. This study was designed to systematically review the impact of soft liners' use on the masticatory efficiency in denture wearers.