Visual and instrumental agreement in dental shade selection: three distinct observer populations and shade matching protocols.

OBJECTIVES: This study tested the hypothesis that the agreement between observer visual dental shade matches and instrumental shade identification is higher using the Vita 3D-Master (3D) shade guide than the Vita classical (VC) shade guide. METHODS: Three populations selected shade matches: non-dental observers (GP) matched shade tabs-to-tabs and dental students (DS) and dentists (DD) matched an in vivo natural right upper central incisor (RUCI). All observers (n=600) used both shade guides (3D and VC) in two lighting conditions, cool white fluorescent lighting (CWF) and natural sunlight (NSL). The shade tabs and natural teeth were identified using an intra-oral spectrophotometer (Vita Easyshade) to determine the instrumental agreement with the visual shade selection. The percent visual-instrumental shade agreement (PVIA) was analyzed statistically considering: observer population, shade guide set, and lighting condition. RESULTS: A "substantial" intra-examiner agreement (k=0.76) was observed. The PVIA ranged from 12% (DS) for the 3D-NSL condition to 42% (DD) with the VC-CWF condition, which also resulted in the highest PVIA for GP (38.5%) and DS (35%). Results indicated that the GP with neither dental knowledge nor shade guide experience had a significantly higher PVIA using the VC rather than the 3D shade guide. Dentists demonstrated the highest PVIA (42%) for both lighting conditions and shade guides, thereby rejecting the study hypothesis. SIGNIFICANCE: A significantly higher visual-instrumental shade agreement was demonstrated by the clinically experienced dentists (DD), regardless of shade guides and lighting conditions.

Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations

The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35 percent phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1 percent methylene blue dye solution at 24°C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations.

The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24 degrees C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.