The effect of thermocycling on the bonding of different restorative materials to access opening through porcelain fused to metal restorations

Abstract

PURPOSEPorcelain fused to metal (PFM) crowns provide the best treatment option for teeth that have a large or defective restoration. More than 20% of teeth with PFM crowns or bridges require non-surgical root canal treatment (NSRCT). This may be due to the effect of restorative procedures and the possible leakage of bacteria and or their by-products, which leads to the demise of the tooth pulp. Thus, this study was planned to compare the ability of the restorative materials to seal perforated PFM specimens.MATERIALS AND METHODSThe study evaluates the ability of amalgam, composite or compomer restorative materials to close perforated PFM specimen's in-vitro. Ninety PFM specimens were constructed using Ni-Cr alloys and feldspathic porcelain, and then they were divided into 3 groups: amalgam (A), composite + Exite adhesive bond (B) and compomer + Syntac adhesive bond (C). All the PFM samples were embedded in an acrylic block to provide complete sealing of the hole from the bottom side. After the aging period, each group was further divided into 3 equal subgroups according to the thermocycling period (one week for 70 cycles, one month for 300 cycles and three months for 900 cycles). Each subgroup was put into containers containing dye (Pelikan INK), one maintained at 5℃ and the other at 55℃, each cycle for 30 sec time. The data obtained was analyzed by SPSS, 2006 using one way ANOVA test and student t-test and significant difference level at (P<.01).RESULTSThe depth of dye penetration was measured at the interfaces of PFM and filling materials using Co-ordinate Vernier Microscope. The lowest levels of the dye penetration for the three groups, as well as subgroups were during the first week. The values of dye leakage had significantly increased by time intervals in subgroups A and C.CONCLUSIONIt was seen that amalgam showed higher leakage than composite while compomer showed the lowest level of leakage.

Surface roughness and color measurements of glazed or polished hybrid, feldspathic, and Zirconia CAD/CAM restorative materials after hot and cold coffee immersion

“…One subgroup was obtained as glazed from the laboratory, and further measurements were carried out without any surface treatments. Another subgroup (16 each) was polished with an OptraFine polishing kit (Ivoclar, Vivadent, Germany), as per the manufacturer’s instructions under constant load (2 ± 0.25 kg) using an equal number of grinders in a single direction [ 27 ]. Polishing steps are first, finishing = F (light blue), second polishing = P (dark blue).…”

Assessment of Color Stainability of Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) Ceramic Materials After Hot and Cold Coffee Immersion at Different Time Intervals

“…The proper arrangement of this kit is using the Dura-White Stones HP each CN1, FL3, and RE1 for adjusting and finishing, then Ceramisté Points HP each of KN7, PC2, and WH6 in standard, ultra, or ultra II grits for intraoral polishing of all ceramic prosthesis. The recommended average speed for Dura-White Stones is from 5000 to 20 000 rpm while the speed for Ceramisté Points is 10 000 to 12 000 rpm, using equal numbers of grindings in one direction with light, controlled pressure [ 27 ]. Then, all specimens were measured using a VEVOR laboratory analytical balance (Schuler Scientific SLB-124, Milan, ITALY), and a Mettler Toledo Excellence XS 11106015 Model XS64 analytical balance, 61 g capacity, 0.1 mg. readability, and the measured weight was considered as the specimen’s weight before coffee staining and aging.…”

Effects of Khat on Surface Roughness and Color of Feldspathic and Zirconia Porcelain Materials under Simulated Oral Cavity Conditions

“…A feldspathic ceramic VITA VM (R) 13 (VITA, Zahnfabrik, Germany) was used for porcelain build-up. The opaque layer on the metal substrate had a thickness of 0.3 ± 0.1 mm, while the body porcelain had a thickness of 2.0 ± 0.3 mm [37]. The feldspathic MC samples were packed and glazed following the manufacturer's recommendations Figure 1B.…”

“…The first subgroup samples (10 samples from each group) were obtained from the laboratory with glazed surfaces without further treatment, whereas the samples in the second subgroup (10 samples from each group) were polished with a porcelain polishing kit (Figure 3) to represent the clinical situation for the prostheses by using the protocol recommended by the company. The sequential polishing of every 10 samples from each ceramic material was done with polishing burs at equal number of grinding at one direction at constant speed and under control pressure at 5 ± 0.25 kg [37]. every 10 samples from each ceramic material was done with polishing burs at equal number of grinding at one direction at constant speed and under control pressure at 5 ± 0.25 kg [37].…”

“…The sequential polishing of every 10 samples from each ceramic material was done with polishing burs at equal number of grinding at one direction at constant speed and under control pressure at 5 ± 0.25 kg [37]. every 10 samples from each ceramic material was done with polishing burs at equal number of grinding at one direction at constant speed and under control pressure at 5 ± 0.25 kg [37].…”