Effect of thermocycling on the bond strength of a glass-infiltrated ceramic and a resin luting cement

Evaluation and Comparison of Two Different Cleaning Procedures on Mechanical Properties for Recemented Restoration Using Two Conventional Glass Ionomer Cement Types: An In Vitro Study

Background In modern dentistry, fixed dental prostheses are often the preferred and the most complex treatment procedures. However, the success of these procedures depends to a great extent on the durability and consistency of the ongoing reconstruction. This paper aimed to compare the shear bond characteristics of conventional glass ionomer cement types, namely, Vivaglass luting cement and GC fuji 1 cement, after being subjected to two different dentin-cleaning techniques: the tungsten carbide bur and the prophy jet. This would help determine whether the castings that have been cleaned and recemented are just as tenacious as when they were initially placed. Methodology A total of 60 human teeth extracted due to periodontal disease were collected for this study. The teeth were cleaned and stored in a thymol arrangement after carefully removing any leftover fragile tissue. They were randomly grouped as follows: luted with Vivaglass cement (N = 30) in group A and GC fuji 1 cement (N = 30) in group B. Each group's debonded surfaces were arbitrarily split into three subgroups, with each containing 10 samples. This was done to comply with dentin-cleaning techniques for recementation. Results The intergroup bond strengths calculated were compared among the subgroups. The mean strength for subgroup IA was 2.78 ± 0.24 MPa, subgroup IB was 2.60 ± 0.30 MPa, subgroup IIA was 4.39 ± 0.19 MPa, subgroup IIB was 3.80 ± 0.23 MPa, subgroup III A was 4.52 ± 0.22 MPa, and subgroup IIIB was 3.63 ± 0.17 MPa. An analysis of variance test showed there was a significant difference between the subgroups (F = 117.60; P = 0.001). The results revealed that there was a significant difference between the subgroups. Shear bond strength testing was performed using common testing equipment. The results indicated that there was not any significant difference between the mean increases in the shear bond strength of the two luting cement types. However, the GC fuji 1 cement showed greater initial shear bond strength than the Vivaglass cement. Additionally, when the tungsten carbide bur was used as a cleaning technique before recementing, it showed greater shear bond strength compared to the prophy jet. Conclusions The initial shear bond strength of GC fuji 1 (Group B) luting cement was slightly higher than that of Vivaglass (Group A), and the bond strength achieved after recementation with GC fuji 1 and surface cleaning with the carbide bur was the highest among the other three groups.

Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials

PURPOSE

The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials.

METHODS

CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no. 1000. In Group 2, 9.6% hydrofluoric acid gel was applied to ceramics. Three different resin cements (RelyX, Variolink Esthetic and G-CEM LinkAce) were applied to the tubes in 1.2-mm thick increments and light-cured for 40s using LED light curing unit. Half of the specimens (n=10) were submitted to thermal cycling (5000 cycles, 5-55°C). The strength measurements were accomplished with a universal testing machine (Lloyd Instruments) at a cross-head speed of 0.5mm/min until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with multivariate analysis of variance (MANOVA) and Tukey's post hoc tests (α=0.05).

RESULTS

There were significant differences between ceramics and resin cements (p<0.001). However, hydrofluoric acid gel treatment had no effect on bond strength values (p=0.073). In addition, thermal cycling significantly decreased bond strength values of resin cements to ceramics (p<0.001).

CONCLUSIONS

Use of appropriate resin cement systems with different ceramic/glass-polymer materials might promote the bonding capacity of these systems.

The effect of IDS (immediate dentin sealing) on dentin bond strength under various thermocycling periods

PURPOSE

The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system).

MATERIALS AND METHODS

Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (α=.05).

RESULTS

There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis.

CONCLUSION

In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

Enamel deproteinization before acid etching and its effect on the shear bond strength--an in vitro study

OBJECTIVE

This study was undertaken to assess the effect of enamel deproteinization with 5.25% sodium hypochlorite (NaOCl) before phosphoric acid (H3PO4) etching on the shear bond strength ofAdperTM Single Bond 2 adhesive and Filtek Z-350 XT composite resin.

STUDY DESIGN

Forty human sound permanent molars which were extracted for periodontal reasons were used in the experimental protocol as under: Group-A (20 teeth):-A 5X4 mm window of the enamel surface was etched with 37% H3PO4 gel for 15 seconds, washed with distilled water and air dried. A single coat of Adper Single Bond 2 adhesive was applied and photo polymerized for 20 seconds and Filtek Z-350 XT composite resin block of length 5 mm, width 4 mm and height 5mm respectively was built and photo polymerized in increments for 20 seconds each. Group-B (20 teeth):--Similarly the enamel surface was treated with 5.25% NaOCl for 60 seconds, washed with distilled water and then etched with 37% H3PO4 gel for 15 seconds, washed with distilled water and air dried. A single coat of Adper Single Bond 2 adhesive was applied and photo polymerized for 20 seconds and Filtek Z-350 XT composite resin block of length 5 mm, width 4 mm and height 5 mm respectively was built and photo polymerized in increments for 20 seconds each. The shear bond strength of all the samples were measured (in MPa) on Instron Mechanical Testing Machine.

RESULTS

The mean shear bond strength value for Group-A was 13.51 +/- 5.726 MPa and for Group-B being 15.06 +/- 6.220 MPa. No statistically significant difference in the shear bond strengths was observed between the two groups.

CONCLUSIONS

No significant effect of sodium hypochlorite enamel deproteinization on the shear bond strength of Adper Single Bond 2 adhesive and Filtek Z-350 XT composite resin before acid etching was observed in this study.

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures.

OBJECTIVES

The aim of this study was to compare the biaxial flexural strength of three core ceramic materials.

MATERIAL AND METHODS

Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872.

RESULTS

The mean biaxial flexural strength values were: Turkom-Cera: 506.8 ± 87.01 MPa, In-Ceram: 347.4 ± 28.83 MPa and Vitadur-N: 128.7 ± 12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N.

CONCLUSIONS

Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.