Interfacial fracture toughness of universal adhesive systems treated with an antioxidant

Background: Secondary caries, degradation of the dentin-resin interface and fracture of the restoration are the most common forms of failure. The aim of this study was to assess the interfacial fracture toughness of three different adhesive approaches and to compare their fracture toughness after surface treatment with antioxidant. Material and Methods: Seventy two dentin blocks with 3×4mm dimension and 3mm thickness were prepared and attached to precured 3×4×12mm composite blocks from both sides. Six adhesive groups (N=12), All-bond universal, Scotchbond universal and Clearfil SE bond with or without antioxidant treatment (Sodium Ascorbate 10% )were applied to dentin surfaces, a 160? polyethylene paper formed the chevron in adhesive-dentin interfaces. Chevron-notched beam fracture toughness was measured following a modified ISO 24370 standard. The uniform composite-dentin-composite block was subjected to a 4-point test in universal machine. Data were analyzed by Kruskal-Wallis, Wilcoxon signed-rank and Mann-Whitney tests (? =0.05). Results: Different adhesive approaches yielded different significant in fracture toughness rates. A significant increase of fracture toughness was observed between adhesive groups after antioxidant surface treatment. The difference in fracture toughness between Scotchbond universal and All-bond universal were significant. Conclusions: The highest value of fracture toughness was reported for Clearfil SE bond and the lowest value was found for All-bond universal. Sodium ascorbate as antioxidant surface treatment had a significant effect in increasing the fracture toughness

Assessment of Microleakage of Class V Composite Resin Restoration Following Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) Laser Conditioning and Acid Etching with Two Different Bonding Systems

INTRODUCTION: The use of laser for cavity preparation or conditioning of dentin and enamel surfaces as an alternative for dental tissue acid-etch have increased in recent years. The aim of this in vitro study was to compare microleakage at enamel-composite and dentincomposite interfaces following Erbium-Doped Yttrium Aluminum Garnet(Er:YAG) laser conditioning or acid-etching of enamel and dentin, hybridized with different bonding systems.METHODS: Class V cavities were prepared on the lingual and buccal surfaces of 50 recently extracted intact human posterior teeth with occlusal margin in the enamel and gingival margin in the dentin. The cavities were randomly assigned to five groups: group1:conditioned with laser (Energy=120mJ, Frequency=10Hz, Pulse duration=100μs for Enamel and Energy=80mJ, Frequency=10Hz, Pulse duration=100μs for Dentin) + Optibond FL, group2:conditioned with laser + etching with 35% phosphoric acid + Optibond FL, group3:conditioned with laser + Clearfil SE Bond, group 4 (control):acid etched with 35% phosphoric acid + Optibond FL, group 5 (control): Clearfil SE Bond. All cavities were restored using Point 4 composite resin. All samples were stored in distilled water at 37°c for 24 h, then were thermocycled for 500 cycles and immersed in 50% silver nitrate solution for 24 h. The teeth were sectioned bucco-lingually to evaluate the dye penetration. Kruskal-Wallis & Mann-Whitney tests were used for statistical analysis.RESULTS: In occlusal margins, the least microleakage showed in groups 2, 4 and 5. The maximum microleakage was observed in group 3 (P=0.009). In gingival margins, the least microleakage was recorded in group2, while the most microleakage was found in group 5 (P=0.001). Differences between 5 study groups were statistically significant (P<0.05). The microleakage scores were higher at the gingival margins.CONCLUSION: The use of the Er:YAG laser for conditioning with different dentin adhesive systems influenced the marginal sealing of composite resin restorations

Bond strength of composite resin to enamel: assessment of two ethanol wet-bonding techniques.

Ethanol wet-bonding (EWB) technique has been stated to decrease degradation of resin-dentin bond. This study evaluated the effect of two EWB techniques on composite resin-to-enamel bond strength.Silicon carbide papers were used to produce flat enamel surfaces on the buccal faces of forty-five molars. OptiBond FL (OFL) adhesive was applied on enamel surfaces in three groups of 15 namely: Enamel surface and OFL (control);Protocol 1 of the EWB technique: absolute ethanol was applied to water-saturated acid-etched enamel surfaces for 1 minute before the application of ethanol-solvated hydrophobic adhesive resin of OFL 3 times;Protocol 2: progressive ethanol replacement; water was gradually removed from the enamel matrix using ascending ethanol concentrations before OFL application. Composite build-ups were made and the specimens were stored for 24 hours at 37°C and 100% relative humidity. Shear bond strength test was performed using a universal testing machine at 1 mm/min crosshead speed. Fracture patterns were evaluated microscopically. Data were analyzed with one-way ANOVA and Fisher's exact test (α=0.05).There were no significant differences in bond strength between the groups (P=0.73). However, regarding failure patterns, the highest cohesive enamel fractures were recorded in groups 2 and 3.In this study, although both methods of EWB did not influence immediate bond strength of composite resin to enamel, the majority of failure patterns occurred cohesively in enamel

A review of adhesives and cements used in all-ceramic restorations and tooth-colored fiber posts

Introduction: The clinical success of indirect restorations is influenced by several factors, including selection of a suitable cement. The introduction of adhesive resin systems has led to increased use of bonded all-ceramic restorations. The aim of this study was to review adhesives, particularly adhesive resins and their clinical characteristics, considerations and requirements in an attempt to assist dentists in selecting appropriate adhesive cements in special clinical situations. Materials and Methods: This review paper used a scientific search for library resources, books and websites of Pubmed and ISI Web of Science in connection with articles published up to 2012 on classification and types of dental cements, their clinical applications, the mechanism of curing resin cements, bonding mechanisms and biocompatibility, adhesion principles, current issues in the field of fiber posts in root canal cementation and surface preparation of dental ceramics. In addition, a variety of surface preparation methods available for fiber posts and different dental ceramics were discussed. Conclusion: New materials are constantly marketed by manufacturers, making it difficult to select appropriate cements and to teach cement application. Selection of an appropriate cement is very important because the dentist will be able to apply a suitable surface treatment on the cemented surface. When optimal compressive strength, minimal film thickness and low solubility in water are desirable, conventional cement materials are desirable; however, these cements require ideal tooth surface preparation. Conventional cements are used for porcelains that are not etchable. On the other hand, due to the superior physical properties of resin cements and higher aesthetics compared to conventional cements, they are good choices for cementation of metal-free restorations

A randomized clinical trial evaluating the success rate of ethanol wet bonding technique and two adhesives

Background : Composite resin restorations may have a short lifespan due to the degradation of resin-dentin interface. Ethanol wet bonding technique may extend the longevity of resin-dentin bond. The purpose of this one year randomized clinical trial was to compare clinical performance of two adhesives with ethanol wet bonding technique. Materials and Methods: This randomized clinical trial was performed on 36 non-carious cervical lesions in 12 patients restored with composite resin using one of the following approaches: 1. OptiBond FL (Kerr, USA); 2. Clearfil SE Bond (Kuraray, Japan) with enamel etching and 3. Ethanol wet bonding technique with the part of adhesive of OptiBond FL. The clinical success rate was assessed after 24 h, 6, 9 and 12 months according to the United States Public Health Service (USPHS) criteria: Marginal discoloration, marginal defect, retention rate, caries occurrence, and postoperative sensitivity. The tooth vitality was also assessed. Results : The retention rate was 100% at baseline and at 6 months follow up for all types of bonding protocols and was 91.67% at 9 and 12 months follow up for ethanol wet bonding group. None of the restorations in three groups showed marginal defects, marginal discoloration or caries occurrence and were vital after 12 months. There was no statistically significant difference between three groups after 12 months follow up (p value = 0.358). Conclusions : Composite restorations placed using ethanol wet bonding technique presented equal performance to the other groups

Non-invasive management of fused upper incisors

The union of two different dental sprouts which can happen in any phase of dental development is commonly called fusion. This developmental anomaly may cause clinical problems including esthetic impairment, which are mainly treated by endodontic and surgical treatments. There are a few reports of conservative not invasive treatment of fused incisors teeth through restorative or prosthetic techniques. They are rarely reported in mandibular posterior teeth. This paper presents an unusual case of fusion of 7 and 8, and also 9 and 10 teeth which was treated with a nonendodontic and nonsurgical conservative approach. Patient was a healthy18-year-old female with chief complaint of bad-looking teeth that in intraoral examination revealed the fusion of 7 and 8, and also 9 and 10 teeth. The space between the mesial of the 6 and 11 teeth was reconstructed. Diastema between the fused teeth was closed. A new lateral tooth was replaced between the fused teeth (7 and 8) and 6 tooth with direct fiber-reinforced composite. The space between the fused teeth (9 and 10) and also tooth 11 was partially closed. Gingival papillas were reconstructed using pink composite. The mandibular anterior missing teeth were replaced with rochett bridge. At the end of treatment the esthetic of the patient was improved. As the treatment was not invasive, major complications are not expected; however, there is potential for eventual long-term periodontal problems due to poor oral hygiene. Debonding of the rochett bridge may happen as well

Fracture toughness of bleached enamel: Effect of applying three different nanobiomaterials by nanoindentation test

Background: Despite the absence of dispute about the efficacy of bleaching agents, a prime concern is about their compromising effect on the enamel structure. This in vitro study investigated whether the addition of three different biomaterials, including nano-bioactive glass (n-BG)/nano-hydroxy apetite (n-HA)/nano-amorphous calcium phosphate (n-ACP), to bleaching agents can affect the fracture toughness (FT) and vickers hardness number (VHN) of bovine enamel. Materials and Methods: The crowns of the newly extracted permanent bovine incisors teeth were separated from the root and sectioned along their central line; one half serving as the control specimen and the other half as the test specimen. After mounting and polishing procedure, all the control specimens (C) were subjected to nano-indentation test to obtain the baseline values of FT. Then, the control specimens were exposed to a 38% hydrogen peroxide for four times, each time for 10 min. The test specimens were divided into three groups and treated as follows, with the same protocol used for the control specimens: Group 1; ACP + hydrogen peroxide (HP) mixed gel; Group 2 BG + HP mixed gel; and Group 3 HA + HP mixed gel. FT measurements with nano-indentation were carried out subsequent to bleaching experiments. Data were analyzed using SPSS and Kruskal–Wallis test (α = 0.05). Results: A significant difference in young's modulus (YM), VHN, and FT at baseline and subsequent to bleaching in control group was observed. However, no significant differences were found in YM, VHN, and FT between the test groups, compared to the respective baseline values. Conclusion: Under the limitations of the current study, it can be concluded that the n-HA, n-ACP, and n-BG could be potential biomaterials used to reduce the adverse effects of tooth bleaching

Comparison of the Dentin Bond Strength of two Self-Etch Adhesives after Prolonged Air-Drying and Additional Light-Curing

Objectives: It has been reported that the water, solvents, or the primer incorporated into adhesive resins decrease the polymerization, compromise the mechanical properties, reduce the bond strength, and lead to a poor bonding performance of self-etch adhesives. This article evaluated the effect of air-drying and light-curing duration of self-etch adhesives on the micro-shear bond strength between composite resin and dentin. Materials and Methods: A total of 120 extracted sound human third molars were randomly divided into twelve groups (n=10). The occlusal dentin in each tooth was exposed. Clearfil SE Bond (CSEB) and Clearfil S3 Bond (CS3B) were used according to the manufacturer’s instructions, followed by air-drying for 3 and 10 seconds in different groups. The adhesives were light-cured for 10, 20 and 40 seconds in different subgroups. Next, the composite resin (Clearfil AP-X) was placed on the dentin surface and was polymerized for 40 seconds. The micro-shear bond strength values were determined using a universal testing machine, and the results were statistically analyzed by three-way ANOVA and Tukey's post-hoc test (α=0.05). Results: CSEB exhibited a significantly higher dentin bond strength than CS3B. Increasing the curing time of CSEB resulted in an increase in the bond strength, whereas an increase in the air-drying time did not affect the bond strength of the two adhesives. Conclusions: Within the limitations of this study, an increase in the curing time improved the bond strength of CSEB, whereas the air-drying time did not affect the bond strength of the evaluated adhesives

In-vitro comparison of the effect of different bonding strategies on the micro-shear bond strength of a silorane-based composite resin to dentin

Background: The current study evaluated the micro-shear bond strengths of a new low-shrinkage composite resin to dentin. Materials and Methods: In this in-vitro study, 70 extracted premolars were assigned to one of seven groups (n = 10): Group 1: OptiBond Solo Plus (Opt; Kerr); Group 2: SE Bond (SE; Kuraray); Group 3: Silorane System Adhesive (SSA; 3M ESPE); Group 4: OptiBond Solo Plus + LS Bond (Opt LS); Group 5: SE Bond + LS Bond (SE LS); Group 6: OptiBond Solo Plus (Opt Po); and Group 7: SE Bond (SE Po). Occlusal dentin was exposed and restored with Filtek LS (3M ESPE) in groups 1 to 5 and Point 4 (Kerr) in groups 6 and 7. After thermocycling (1000 cycles at 5/55΀C), micro-shear bond test was carried out to measure the bond strengths. The results were submitted to analysis of variance and post hoc Tukeytests (P < 0.05). Results: Two-way ANOVA showed no significant differences between the two types of composite resin (P = 0.187), between bonding agents (P = 0.06) and between composite resin and bonding agents (P = 0.894). Because P value of bonding agents was near the significance level, one-way ANOVA was used separately between the two composite groups. This analysis showed significant differences between silorane composite resin groups (P = 0.045) and Tukey test showed a significant difference between Groups 4 and 5 (P = 0.03). Conclusion: The application of total-etch and self-etch methacrylate-based adhesives with and without use of a hydrophobic resin coating resulted in acceptable bond strengths

Effect of antioxidants on push-out bond strength of hydrogen peroxide treated glass fiber posts bonded with two types of resin cement

Objectives Hydrogen peroxide (H2O2) surface treatment of fiber posts has been reported to increase bond strength of fiber posts to resin cements. However, residual oxygen radicals might jeopardize the bonding procedure. This study examined the effect of three antioxidant agents on the bond strength of fiber posts to conventional and self-adhesive resin cements. Materials and Methods Post spaces were prepared in forty human maxillary second premolars. Posts were divided into five groups of 8 each: G1 (control), no pre-treatment; G2, 10% H2O2 pre-treatment; G3, G4 and G5. After H2O2 application, Hesperidin (HES), Sodium Ascorbate (SA) or Rosmarinic acid (RA) was applied on each group respectively. In each group four posts were cemented with Duo-Link conventional resin cement and the others with self-adhesive BisCem cement. Push-out test was performed and data were analyzed using 2-way ANOVA and tukey's post-hoc test (α = 0.05). Results There was a statistically significant interaction between the cement type and post surface treatment on push-out bond strength of fiber posts (p < 0.001, F = 16). Also it was shown that different posts' surface treatments significantly affect the push-out bond strength of fiber posts (p = 0.001). H2O2 treated posts (G2) and control posts (G1) cemented with Duo-link showed the highest (15.96 ± 5.07MPa) and lowest bond strengths (6.79 ± 3.94) respectively. Conclusions It was concluded that H2O2 surface treatment might enhance the bond strength of fiber posts cemented with conventional resin cements. The effect of antioxidants as post's surface treatment agents depends on the characteristics of resin cements used for bonding procedure