Journal of Dental Medicine

Statement of Problem: Ceramics and resins belong to the earliest tooth restorative materials. Nowadays new generations of these materials have provided a revolution in cosmetic dentistry. Ceramic Optimized polymer (Ceromer) is a newly made product that the bond between this material and base metal alloys, which are used widely today, is paid too much attention.

Purpose: The aim of this study was to evaluate the bond strength of targis (Ceromer) to three types of base metal alloys through three different surface treatment methods.

Materials and Methods: In this experimental study, ninety plates of Rexillium III, Silver cast and super cast alloys (3050.4) were prepared and surface treated through three different methods (air oxidation, vaccum oxidation and sandblast). All samples were then veneered with 1.mm thickness of Targis. After thermocycling, three-point bending test was performed by universal testing machine (Instron) to evaluate the amount of forces at crack or fracture times in Targis. The type of failure (cohesive or adhesive) was also evaluated microscopically. Statistical analyses were made using 2-factor ANOVA and Duncan tests.

Results: The type of surface treatment method caused a statistically significant difference in force rate required for crack and fracture in Targis. Sandblasting was found as the best method. The type of alloys, in all three methods, had a significant effect just on crack creation attributing the largest amount of force to Rexillium III. Adhesive type of failure occurred mostly in super-cast alloys through air-oxidation method, and cohesive type was more among silver cast alloys and sandblast method.

Conclusion: According to the results of this study, bond strength between Ceromer materials and base metal alloys is significantly great and Rexillium III alloy associated with sandblast technique the best combination.

Background and Aim: As central incisors have a prominent role in esthetics, appropriate preparation, considering natural tooth anatomy and proper planes have always been considered. The aim of this study was to determine the number of planes in labial surface of maxillary central incisors using image processing and mathematical analysis.

Materials and Methods: This pilot study was performed on 32 intact maxillary central incisors in dental students of Tehran university of medical sciences. Photographs were taken from profile view of each tooth by a digital camera. Images were processed and number of planes was obtained using SigmaScan Pro. version 5.00 software and a customized program. Data were analyzed by t-test and regression tests with p<0.05 as the level of significance.

Results: 96.9% of central incisors had three planes and 3.1% had two planes in labial surface. The angle between middle-cervical and middle-incisal planes showed statistically significant difference (p< 0.01).

Conclusion: Based on the results of this study, a few percentage of maxillary central incisors had two planes and most of them had three planes in their labial surfaces. Thus, considering three planes for restoring maxillary central teeth is closer to principles of tooth preparation and esthetics.

Background and Aim: Various studies have shown that reliable bond at the root - post - core interfaces are critical for the clinical success of post - retained restorations. Severe stress concentration at post - cement interface increases post debonding from the root. To form a bonded unit that reduces the risk of fracture, it is important to optimize the adhesion. Therefore, some post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of tooth - colored posts on the bonding of resin cement.

Materials and Methods: In this interventional study, 144 tooth colored posts were used in 18 groups (8 samples in each group). The posts included quartz fiber (Matchpost), glass fiber (Glassix), and zirconia ceramic (Cosmopost) and the resin cement was Panavia F 2.0. The posts received the following surface treatments: 1- No surface treatment (control group), 2- Etching with HF and silane, 3- Sandblasting with Cojet sand, 4- Sandblasting with Cojet sand and application of silane, 5- Sandblasting with alumina particles, 6- Sandblasting with alumina particles and application of silane. Then, posts were cemented into acrylic molds with Panavia F 2.0 resin cement. The specimens were placed in water for 2 days and debonded in pull - out test. Statistical analysis was performed using ANOVA followed by Tamhane and Tukey HSD. Failure modes were observed under a stereomicroscope (10 ). P<0.05 was considered as the significant level.

Results: Surface treatments (sandblasting with Cojet and alumina particles ,with or without silane) resulted in improved bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost) [p<0/05], but not to the quartz fiber post (Matchpost). In general, higher bond strengths resulted in a to higher percentage of cohesive failures within the cement.

Conclusion: Based on the results of this study, sandblasting with cojet and alumina particles increases bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost).Generally, the bond strength of resin cement to the posts is affected by the post's composition and surface treatment.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. Surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.

Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.

Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005). There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).

Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

  Background and Aims: Hepatitis B is an important infection route in dentistry requiring different disinfectants to prevent its transmission. The aim of this study was to compare the effects of chemical disinfectants (FD366, ISORAPID and 5% sodium hypochlorite 2/100) to remove Hepatitis B infections from the dental surfaces.

  Materials and Methods: In this experimental laboratory trial, serum of 10 HBV patients was poured into microtubes, FD366, ISORAPID and hypochlorite disinfectants were added to them. PCR experiments with viral diagnostic kits were used to diagnose the virus genome. Real time PCR was used to evaluate after incubation with the disinfectants. The reductions occurred in the viral load of Hepatitis B were statistically analyzed using Kruskal-wallis and Mann-Whitney U tests .

  Results: No significant antiviral efficacy was noted following the application of FD366 and ISORAPID disinfectants (P=0/07). However, hypochlorite showed the most efficacy to disinfect Hepatitis B and a significant difference was found among them (P<0.0001).

  Conclusion: Under the study limitations, FD366 and ISORAPID disinfectants did not show adequate efficacy to remove Hepatitis B virus. Hypochlorite was the most effective disinfectant.