"The Effect of Repair Site Preparation on Color Matching and Blend Effect of Resin Composite on Polymer Infiltrated Ceramic"

Abstract

Color matching and blend effect of Resin Composite on Polymer Infiltrated Ceramic is affected by the repair site preparation. The present study assesed the effect of three preparation extensions on the color match and blending effect of repair resin on polymer infiltrated ceramic with two different types of composite resin. Materials and methods: Vita enamic blocks were cut into 2mm thickness, 7mm width and 10 mm length. Standardization of preparation for the specimens was done using Stainless steel mold. The guided part of the mold had 2 designs according to the preparation design. Design Sk: to form a uniform slots of depth cuts 1mm depth and 1mm length at the line angel of the slice called Skirting and design Bv: to guide the stone to form a 2mm bevel at the line angle with depth of the bevel 1mm.The specimens of total number 42; 14 specimen with skirting (design A), 14 specimen with beveling (design B) and 14 specimen with butt joint (needed no preparation due to the sectioning step of specimens).These groups were divided in to two subgroups according to type of composite; nanofilled and microfilled. Then the specimens were treated before composite application by air abrasion 45 μm aluminum oxide particles with 10 mm distance from the tip of the blasting device, 2.5 bar pressure, 90° angulation, for 10 seconds; cleaning of the specimens in ultrasonic bath in distilled water for 5 minutes. Followed by etching with hydrofluoric acid 9.5% for 60 seconds; washing with air-water spray for 60 seconds and air-drying for 5 seconds. Active application of the silane coupling agent for 20 seconds waiting for 5 minutes for volatilization of the ethanol. Finally active application of the All Bond Universal adhesive system for 10 seconds, followed by a light air jet for 5 seconds, and photo-activation for 10 seconds. Teflon mold was fabricated with 14 mm and 10mm to accommodate two halves; one half was the vita Enamic specimen and the other half the composite resin was filled with Teflon instrument and light cured. The resin composite restorations were finished and polished using silicon carbide disks with mild hand pressure. A Black paper with 6mm diameter circle was used to expose the part of the specimen to be evaluated, at the repaired site (line of demarcation).The circle was centralized on the repaired area with different designs; Butt preparation: the center at the repaired line, Bevel preparation: the center of the circle at the center of the bevel 1mm from the edge and Skirt preparation: the center 0.5mm from the edge. The color parameters of the specimens were measured using a spectrophotometer. The 3 observer function was used with the CIE Illuminant D65, ∆E between the main disc shade of the vita enamic and the repaired specimens at the line of repair were calculated according to the following equation : ΔE = [(L2n-L1) 2 + (a2n-a1)2+ (b2n-b1) 2]1\2 where L*, a*, and b* are the CIELAB color coordinates. The results were confirmed by Visual assessment was performed by seven normal color-vision-professional observers to determine the color-matching between the VE specimen and repaired specimens in all experimental groups shade, under Illuminant D65. Color-matching visual scoring (VS) values were expressed numerically (1–5). Results showed that the interaction between the two variables had a statistically significant effect on the mean color difference. In which the color difference (ΔE *) between Vita Enamic and all experimental groups showed that the least ΔE * values were produced by the Bevel Micro group.