Date of Degree
Access restricted until 09/04/2021
MS (Master of Science)
Maia, Rodrigo Rocha
First Committee Member
Vidal, Cristina D.
Second Committee Member
Third Committee Member
OBJECTIVE: To evaluate the effects of different times and temperatures of coffee exposures on the color stability of three types of dental composites (DC).
METHODS: Three types of DC were used to fabricate standardized discs (n=288; n=96/DC): microfill (Durafill VS), microhybrid (Z100TM), and nanofill (Estelite OMEGA) of shade A2. Each disc was 2mm in thickness and 9mm in diameter. After being light cured with a Quarts tungsten halogen (QTH) unit at the energy level recommended for each DC, discs were polished using sand paper under water irrigation. All samples were initially stored in an incubator in distilled water for 24-hours at 37 65ºC and each DC group was further divided into 6 subgroups (n=16/per group): 65ºC coffee, 37ºC coffee, 4ºC coffee, 65ºC distilled water, 37ºC distilled water, 4ºC distilled water (control group with water media). Baseline color was measured by spectrophotometer (Easy VITA shade compact) with color changes (ΔE*) recorded after 1-day, 3.5-days, and 7-days. The statistical analysis revealed no interactions between DC, temperature, and time of incubation and the main effects were examined using one-way ANOVA followed by the post-hoc Tukey’s HSD test or a Bonferroni adjustment (alpha=0.05).
RESULTS: Mean (ΔE*) observed with coffee exposures for the microfill DC (11.58±6.37) was statistically significant higher than for the nanofill DC (10.64±6.77; p<0.001), and mean (ΔE*) for the nanofill DC was significantly higher than for the microhybrid DC (9.26±5.83; p<0.001). For all DC, mean (ΔE*) observed with coffee exposure at 65ºC (18.33±4.32) was significantly higher than at 37°C (7.03±2.05; p<0.001), and mean (ΔE*) at 37ºC was significantly higher than at 4ºC (6.11±2.67; p<0.001). Mean (ΔE*) after coffee exposure for 1 day (8.64±5.35) was significantly lower than for 3.5-days (11.07±6.50; p<0.001) and 7-days (11.76±6.84; p<0.001); while no difference was observed between 3.5-days and 7-days of incubation (p=0.0769).
CONCLUSION: The findings of this study indicated that exposure time, temperature, and composite type affect the color stability of DC, with higher temperature affecting the color stability more than lower temperatures. Also, color stability was affected more by increasing the exposure time.
Beverages, Color stability, Dental composites, Temperature
xv, 115 pages
Includes bibliographical references (pages 111-115).
Copyright © 2019 Arwa Ali Alhakami
Alhakami, Arwa Ali. "Effect of time and temperature on the color stability of dental composite." MS (Master of Science) thesis, University of Iowa, 2019.
Available for download on Saturday, September 04, 2021