Yusuf Ismail Osman

A Clinical Study of the Effectiveness of a Light Emitting Diode System on Tooth Bleaching

The purpose of this study was to evaluate the efficacy of a Light Emitting Diode (LED) System (BriteWhite) on tooth bleaching. Method: eeth 11 and 21 of twenty one subjects were treated in the chair with a LED light and 44% carbamide peroxide gel, followed by an at-home treatment period of 14 days with 35% carbamide peroxide. The color of the teeth was measured with a spectrophotometer (L*; a*; b*) before treatment (control) and after the above mentioned two stages. The subjects were also instructed to note tooth and gingival sensitivity. Results: For the L* component a statistically significant difference (p<0.05) between base-line and directly after the LED treatment stage (whiter) was found and a complete relapse was found after the 14 day at-home treatment period. The b* component showed statistically significant differences (p<0.05) between base-line and the LED stage (less yellow more blue), with a further significant color improvement after the 14 day treatment period. For the a* component (green to red) no statistically significant change was (p>0.05) found throughout the study (Wilcox on Signed Rank Sum Test). A major color change of 1.8 units (ΔEab) was found after the LED treatment stage with only a further small 0.2 unit improvement after the 14 day at-home treatment stage. Tooth and gingival sensitivity scores were low (below mild) throughout the treatment stages. Conclusion: A major tooth color increase was found after the in-office LED/gel treatment stage and only an insignificant further improvement was noted after the additional 14 day at-home treatment period. Only low tooth and gingival sensitivity scores were found. A slight increase in both the sensitivity and gingival scores after the LED/gel activated stage could be observed. Overall the total color increase was low.

Volumetric change of flowable composite resins due to polymerization as measured with an electronic mercury dilatometer

Abstract Background: To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. Materials and methods: A specially