Bond Strength Of Composite Restorations Research Articles

Influence of different endodontic irrigants on shear bond strength of composite resin to coronal dentin: An in vitro study

Objectives: Endodontic irrigants are critical in root canal treatments, but their influence on the coronal dentin bond strength of composite restorations is a key concern for a favorable clinical prognosis. The present in vitro study explores the effect of different endodontic irrigants on shear bond strength of composite resin. Material and Methods: Fifty permanent human mandibular molars were sectioned to expose coronal dentin and divided into five groups. Each group received a specific irrigant treatment before composite resin bonding. Shear bond strength was examined using Instron Universal testing machine, and statistical analysis was conducted using post hoc Tukey’s test and analysis of variance. Results: Group A (Saline) showed a mean shear bond strength of 18.5 Megapascal (MPa). Group B [sodium hypochlorite (NaOCl)] had mean shear bond strength of 15.2 MPa. Group C [Chlorhexidine (CHX) Gluconate] exhibited mean shear bond strength of 20.3 MPa. Group D ethylenediaminetetraacetic acid (EDTA) recorded mean shear bond strength of 14.8 MPa, while Group E [citric acid (CA)] had the highest mean shear bond strength at 22.7 MPa. Conclusion: The type of endodontic irrigant used significantly affected the shear bond strength of composite restorations to coronal dentin. CHX gluconate and CA displayed superior bond strengths compared to Saline, NaOCl, and EDTA. This underscores the importance of irrigant selection in achieving successful composite restorations in endodontically treated teeth.

Phycocyanin-loaded silver nanoparticles activated with photodynamic therapy and Nd: YAG laser for caries-affected dentin disinfection: Impact on Streptococcus mutans survival rate and shear bond strength to the tooth-colored restorative material

AimsTo assess the impact of various cavity disinfectants PC-PDT (Phycocyanin activated by Photodynamic therapy), PC@AgNPs-PDT (Phycocyanin and silver nanoparticles activated by PDT), and Nd: YAG laser on the survival rate of S.mutans and the bond integrity of composite restoration MethodsSixty human mandibular molars that scored 4 and 5 based on ICDAS criteria were included. The infected dentin was removed while the CAD was preserved based on visual, tactile, and staining assessment. S.mutans were cultured on the CAD of twenty samples. All the specimens were indiscriminately distributed into four groups based on cavity disinfection (n=20 each includes n = 5 each group incubated with S.mutans) Group 1: CHX, Group 2: Nd:YAG laser, Group 3: PC-PDT and Group 4: PC@AgNPs-PDT. S.mutans survival rate was assessed for each group(n = 5). Forty samples underwent composite bonding for SBS and failure mode assessment using universal testing machine (UTM) and stereomicroscope. The calculations for the mean and standard deviation (SD) and their comparison among different groups were performed using a one-way analysis of variance (ANOVA) and the Tukey post hoc test (p ≤ 0.05) ResultsCAD surface treated disinfected with PC@AgNPs-PDT yielded the lowest survival rates (0.13 ± 0.05 CFU/ml) and highest SBS (17.23 ± 1.45 MPa). Group 1 (CHX) unveiled the highest survival rate of S.mutans (0.33 ± 0.12 CFU/ml). However, Group 2 (Nd:YAG Laser) (11.87 ± 0.67 MPa) presented the lowest SBS ConclusionThe combination of Phycocyanin loaded with silver nanoparticles and activated with Photodynamic therapy demonstrates the highest antimicrobial potential and bond strength of composite restorations.

Effect of bioactive glass-containing dentin adhesives on microshear bond strength of composite restorations

Effect of bioactive glass-containing dentin adhesives on microshear bond strength of composite restorations

29 - Influence of Bromelain and Biosilicate on Adhesive Bond Strength

This study evaluated the effect of bromelain associated with Biosilicate on the bond strength (BS) of composite restorations to sound and caries-affected dentin. 360 sound human molars were selected, and occlusal cavities (6 mm×6 mm x 3 mm) were prepared using carbide burs. Half of them were submitted to cariogenic challenge with Streptococcus mutans strain ATCC25175. All the teeth were separated into nine groups (n = 20), according to the treatment received before the adhesive system (Single Bond Universal, 3 M ESPE): Control group Adhesive System (two coats in self-etch mode); CHX group 0,12% chlorhexidine; NaOCl group 5% sodium hypochlorite; Bio group 10% Biosilicate; Br5 group - 5% bromelain; Br10 group - 10% bromelain; Br5Bio group 5% bromelain + 10% Biosilicate; Br10Bio group 10% bromelain + 10% Biosilicate; NaOClBio group 5% sodium hypochlorite + 10% Biosilicate. After restorative procedures (Filtek Z350XT, 3 M ESPE), the samples were sectioned into sticks, separated, and stored in distilled water at 37 C for 24 h. After that, the sticks were submitted to microtensile test (0.5 mm/min). Data were analyzed using 2-way ANOVA and Bonferronis test (p <.05). The fracture pattern was observed with digital microscope (VH-M100). The caries-affected dentin presented higher BS (p <.05) than the sound substrate under control conditions and when the surface was treated with Biosilicate. Among the sound samples, there was no difference (p >.05), regardless of the treatment employed. In the caries-affected samples, Control and Br10 groups resulted in higher (p <.05) BS than Br5Bio group, with no difference (p >.05) between them. Br10 group also demonstrated higher values (p <.05) than Br10Bio group. The other groups showed no difference (p >.05). Both substrates presented higher incidence of non-adhesive fractures irrespective of the treatment. The pre-treatments with bromelain and bioactive glass-ceramic can affect the bond strength of composite restorations to sound and caries-affected dentin.

Effect of Contamination with Hemostatic Agent on Shear Bond Strength of Composite to Dentin Using G-Premio and Single Bond Universal Adhesives.

Objectives: Bond strength of composite restorations plays an important role in their success. This in vitro study evaluated the effect of a hemostatic agent on shear bond strength of universal adhesives. Materials and Methods: Thirty-six extracted human molars were used in this study. Buccal and lingual surfaces were reduced to obtain flat dentin surfaces and were ground with a silicone paper. The samples were randomly divided into three groups (n=12) based on the application of hemostatic agent: group 1: no contamination (control), group 2: aluminum chloride application, and group 3: ferric sulfate application. Each group was then divided into two subgroups (n=6) for using G-Premio and Single Bond Universal. Resin cylinders (Filtek Z550) were bonded to dentin surfaces according to the manufacturer’s instructions. After 1000 thermal cycles, shear load was applied to the specimens using a universal testing machine at a crosshead speed of 1 mm/min until failure. Data were statistically analyzed using two-way ANOVA and Tukey’s post-hoc test (α=0.05). Results: There were statistically significant differences in shear bond strength of the three main groups for both G-Premio and Single Bond Universal (P<0.05). When the adhesive systems were compared with each other, G-Premio showed higher shear bond strength than Single Bond Universal (P<0.05). Conclusion: Contamination with hemostatic agents had an adverse effect on the shear bond strength of universal adhesives. Moreover, G-Premio yielded a higher bond strength than Single Bond Universal.

Efficacy of photodynamic therapy, photobiomodulation and antimicrobial agent on the shear bond strength of composite restorations to hypomineralized teeth

The aim of this study was to investigate the adhesive bond strength and fracture analysis of resin based restorations to carious dentin of hypomineralized molars (HMs) after disinfecting with photodynamic therapy (PDT), Nd:YAG and chlorhexidine (CHX). Sixty carious HM molars were investigated. After removal of all carious infected tissue, the cavities were condition with methylene blue initiated PDT, a 1064 nm wavelength Nd:YAG laser or 2.0% CHX gel. Non-carious dentin from HM was used as a control without performing any disinfection or conditioning technique. All samples were bonded using a one-step one-coat adhesive bond over the dentin surface, packed with composite and light cured. All specimens were subjected to thermocycling at 5°C and 60°C with a dwell time of 30 s for 10,000 cycles. Bonded specimens were placed on a universal testing machine with a flat loading head. The debonded surface were viewed under light optical microscope to estimate the type of failure including adhesive, cohesive, and admixed. The highest mean SBS was seen in the non-carious HM (control group). The mean score for control group was 17.64 ± 2.96 MPa. The lowest bond strength value was displayed for Group-PDT (11.37 ± 3.66 MPa) and Group-Nd:YAG (12.69 ± 2.45 MPa). Affected dentin disinfected with the Group-CHX (15.71 ± 3.04 MPa) bonded with composite showed statistically significantly higher SBS values compared to the laser groups (p < 0.05). No statistically significant difference was noted with specimens disinfected with PDT and Nd:YAG laser showed comparable SBS scores (p > 0.05). Fracture analysis showed equal incidence of adhesive and cohesive failures in control group and Group-CHX. Moreover, a significant number of failures in group-PDT were related to adhesive. Whereas in group 4, admixed type failures were common. Caries infected hypomineralized teeth demonstrated lower bond strength values compared to non-carious hypomineralized teeth. Adhesive bond strength of hypomineralized teeth was highest with chlorhexidine compared to other laser treatment strategies.

Examining the Effect of Laser Radiation on the Repair of Dental Composite Restorations: A Systematic Review

Background: This study aimed to determine the impact of laser radiation on the repair bond strength of dental composite restorations by gathering, assessing, and systematically reviewing previous articles referring to this issue. Methods: Several previous studies relevant to the objectives of this research were found in PubMed, Scopus, and Web of Science databases. All prior articles indexed in these databases according to the selected keywords until 2018 were gathered and assessed. Some article abstracts showed the necessary basic conditions for inclusion in the study. Therefore, the full texts of these relevant articles were further evaluated in terms of the study objectives. Results: A total of 300 relevant articles were obtained by searching the databases. Eight studies remained highly relevant after performing a title review, eliminating the duplicate articles, and implementing the selection criteria. The latest study was conducted in 2018. A statistically significant difference was observed between the impacts of laser and other methods in the seven of these final relevant studies. Of these articles, five indicated a better impact in the case of other methods, particularly the dental milling technique, and one study was related to the impacts of the laser method. Additionally, the Er,Cr: YSGG laser was considered the most adequate laser in these studies. Conclusions: According to the review of prior studies on the impact of laser radiation on the repair bond strength of composite restorations, Er: YAG and Er,Cr: YSGG lasers are advised for surface preparation of composites. However, surface preparation by adopting the milling technique remains the adequate choice for repairing composites.

Effect of Dentin Pretreatment with Chlorhexidine on Push-Out Bond Strength of Composite Restorations in Severely Damaged Primary Anterior Teeth

Objectives:Achieving durable restorations with adequate strength in severely damaged primary anterior teeth in children is a priority. The aim of this study was to investigate the effect of dentin pretreatment with chlorhexidine on push-out bond strength of composite restorations.Materials and Methods:In this in vitro experimental study, 56 extracted primary anterior teeth were randomly divided into 4 groups: (1) saline and total-etch bonding agent, (2) chlorhexidine and total-etch bonding agent, (3) saline and self-etch bonding agent, and (4) chlorhexidine and self-etch bonding agent. After the application of bonding agents, the post space was filled with Z250 composite resin. Following thermocycling of the samples, the push-out test was performed using a universal testing machine, and the results were analyzed with two-way ANOVA.Results:The mean push-out bond strength values in groups 1 to 4 were 5.7, 8.39, 5.35, and 7 MPa, respectively. Chlorhexidine groups had significant differences with saline groups in bond strength (P<0.05) but there was no statistically significant difference between the self-etch and total-etch bonding agents in the groups (P>0.05).Conclusion:Both types of bonding agents (self-etch and total-etch) exhibited favorable results in radicular dentin of primary anterior teeth; however, pre-treatment with chlorhexidine increased the push-out bond strength of composite restorations in primary anterior teeth.

Evaluation of Shear Bond Strength of Composite Restoration by Different Dentin Bonding Systems Under Different Cycling Conditions

Background: Adhesion of composite resins to dentin is crucial in restorative dentistry. The aim of this study was to evaluate shear bond strength of composite restorations to dentin under different cycling conditions. Methods: Ninety extracted premolar teeth were randomly divided into 9 groups (n=10). The samples were mounted in resin and sectioned to prepare dentin samples. Then the samples were polished with 600-grit silicon carbide sanding sheet, and adhesive types of bonding (5th generation/Ambar, 6th generation/Clearfil SE bond, 8th generation/G-Premio) were applied on them. Afterward, composite resin was bonded to the surface, and cycling was exerted (control: no cycling; thermal cycling: 3000 cycles, 5°C to 55°C; thermal/erosive cycling: thermal cycling and storage in hydrochloric acid, pH = 2.1, 5 minutes, 6 times a day, for 8 days). Shear bond test was done for the specimens. Finally, statistical analysis was done using a two-way analysis of variance (ANOVA) and Tukey test (P < 0.001). Results: G-Premio displayed the most bond strength. No significant differences were observed between Clearfil liner bond and Ambar bond. While significant differences were observed in different cycling conditions. Measured bond strength was reduced by thermal/erosive cycling. Conclusions: Thermal cycling and thermal/erosive cycling could affect the shear bond strength of composite to dentin. Universal bonding systems can also increase the shear bond strength of composite resin to dentin.

Evaluation of the bond strength of posterior composites to the dentin, treated with four different desensitizing agents – An In vitro study

Background: Postrestorative sensitivity is frequently associated with composite restorations. Dentin desensitizers are used commonly for the management of postrestorative sensitivity. This study aimed to evaluate the effect of four desensitizing agents on the bond strength of composite restoration. Materials and Methods: Sixty-five human premolars are used for the study. The occlusal surface of each tooth is flattened using a diamond disk to expose the dentin. The specimens are then etched with 35% phosphoric acid for 15 s and divided into five groups (n = 13) Group I – VivaSens, Group II – MS Coat F, Group III – Gluma, Group IV – Systemp, and Group V – Control. Single-step adhesive (Single Bond Universal, 3M) will be applied on the specimens and restored with composite material (Filtek Z350XT, 3 M). Shear bond strength is tested using universal testing machine at a crosshead speed of 1 mm/min. Statistically multiple group comparison was done using one-way analysis of variance followed by Tukey's test for group-wise comparison analysis. Results: Systemp desensitizer showed improved bond strength values than others desensitizers and control group. Conclusions: Systemp desensitizer can be considered as a promising option for preventing postoperative sensitivity associated with resin composite restorations without altering its shear bond strength to dentin.

Evaluation of bond strength of one step and two steps self-etch adhesive agents with two different pulp-capping materials

Primary purpose of restorative dentistry is to preserve pulp vitality. Besides calcium hydroxide, the application of calcium silicate cements as a material for direct pulp capping has become used recently. The aim of our study was to investigate the influence of materials for direct and indirect pulp capping on the bond strength of composite restorations using two different self etch dentin adhesives. The test was performed on 60 intact molars extracted for periodontal or orthodontic reasons. The prepared samples were divided into the two groups and three subgroups depending on the adhesive and pulp cupping material. Two different calcium silicate based materials were used for pulp cupping. One step and two steps self etch dentin adhesive was applied to prepared specimens depending on the group and with the help of a specially made metal mold set up a composite post. The share bond strength was assessed using a universal testing machine. The results showed significant difference in the share bond strength between the samples treated with TheraCal LC and Biodentine with TheraCal LC being superior to Biodentine.

Comparison of Bromelain Enzyme, Sodium Hypochlorite, and Titanium Tetrafluoride on Shear Bond Strength of Restorative Composite to Dentin: An in vitro Study.

Statement of the Problem:Sufficient bond strength of composite restoration leads to its durability and survival; therefore, preparation of dentin surface for higher bond strength is essential. Purpose:Our aim is to assess the deproteinizing effect of 3% bromelain enzyme and compare it to 4% titanium tetrafluoride (TiF4) and 5% sodium hypochlorite (NaOCl) regarding the shear bond strength (SBS) of composite resin to dentin. Materials and Method: In this experimental study, 40 intact extracted human maxillary premolars were selected, and the occlusal surfaces of the teeth were sectioned at a depth of 2 mm from dentinoenamel junction. The teeth were divided into 4 groups (n=10). In Group 1, the teeth were etched with 37% phosphoric acid gel. In Group 2, the teeth were etched and deproteinized with 5% NaOCl. In Group 3, the teeth were etched and deproteinized with 4% TiF4. In Group 4, the teeth were etched and deproteinized with 3% bromelain enzyme. In each specimen, composites with 3 mm diameter and 2 mm height were prepared and cured. The test specimens were then stored in distilled water at room temperature for 7 days before conducting the SBS test (MPa). By universal testing machine at a crosshead speed of 1 mm/min, the results were analyzed using one-way ANOVA and Tukey test. Results:One-way ANOVA test demonstrated that pretreatment of dentin with a bromelain enzyme, TiF4 solution, or NaOCl was not statistically different regarding SBS to dentin (p= 0.790). Conclusion:3% bromelain enzyme can be as effective as TiF4 and NaOCl and phosphoric acid 37% in terms of the SBS of composite resin to dentin.

A comparative evaluation of the three different antioxidant treatments on the bond strength of composite resin to bleached enamel: An in vitro study.

Context:Natural antioxidants have capacity to neutralize the action of free radicles, therefore, effective in reversal of compromised bond strength.Aims:The aim of this study was to investigate the effect of three different antioxidant treatments on the bond strength of composite resin to bleached enamel.Materials and Methods:Ninety extracted human anterior teeth were divided into five groups: Group I (n = 10) – control group no bleaching, Group II (n = 20) – bleaching with 35% carbamide peroxide gel, Group III (n = 20): bleaching with application of 10% sodium ascorbate, Group IV (n = 20): bleaching with application of 6.5% proanthocyanidin, and Group V (n = 20) – bleaching with application of 50% Aloe vera. These groups were further subdivided into two subgroups based on whether composite buildup was done immediately (Subgroup A) or after a delay of 2 weeks (Subgroup B). Shear bond strength of the specimens was tested under universal testing machine.Statistical Analysis Used:Data were statistically analyzed using Student's unpaired t-test, ANOVA test, and Tukey's Kramer multiple comparison test.Results:The mean bond strength of Group IVA was significantly higher (4.27 ± 1.86) which indicated that immediate application of proanthocyanidin showed higher bond strength after bleaching (P < 0.05).Conclusion:Within the limitations of this study, it can be concluded that immediate application of antioxidants on bleached enamel before composite restoration reversed the bond strength of composite restoration. The immediate application of proanthocyanidin proved superior followed by A. vera.

Cavity Preparation by Laser in Primary Teeth: Effect of 2 Levels of Energy Output on the Shear Bond Strength of Composite Restoration to Dentin.

Introduction: One of the main applications of laser in dentistry is the removal of dental caries and preparation of restorative cavities. The morphology and wettability of laser prepared surfaces are different from that of those prepared with conventional method which may affect the quality of the adhesive potential of bonding agents in these surfaces. This study aimed to assess the shear bond strength of a total-etch and self-etch adhesive system to primary tooth dentin prepared by two different energy densities of Er:YAG laser in comparison with surfaces prepared by bur. Methods: A total of 60 human primary second molars extracted for orthodontic purposes were selected and randomly divided into 3 main groups of equal (n=20). Group A: Preparation of dentin surface by bur; group B: Preparation of dentin surface by laser with 300 mJ energy level; group C: Preparation of dentin surface by laser with 400 mJ energy level. In each of the main groups, the teeth were randomly assigned to 2 subgroups. Composite resin material was bonded with the total-etch adhesive system in subgroups A1, B1, and C1 and with the self-etch adhesive system in subgroups A2, B2, and C2. The samples were thermo-cycled, and composite restorations shear bond strength was measured in MPa. Data were analyzed using two-way analysis of variance (ANOVA), and P values less than 0.05 were considered statistically significant. Results: The highest and the lowest shear bond strength values were observed in group A2 (Preparation by bur- Composite resin material bonded by Clearfil SE Bond) and group C2 (Preparation by laser with 400 mJ energy level - Composite resin material bonded by Clearfil SE Bond), respectively. The results showed no statistically significant differences between the study subgroups (P > 0.05). Conclusion: It is concluded that in terms of shear bond strength to dentin, Single Bond and Clearfil SE Bond adhesive agents adequately perform in primary tooth dentin prepared by Er: YAG laser with energy levels of 300 and 400 mJ and frequency of 10 Hz.

Evaluation the effect of eugenol containing temporary fillings on shear bond strength of composite restoration

The purpose of this in-vitro study was to evaluate the effect of eugenol-containingtemporary fillings on shear bond strength of composite to dentin and determine theefficiency of dual bonding technique in improving the bond strength using AdperSingle Bond 2 adhesive with 3M composite. Thirty sound human upper firstpremolars were used in this study. The occlusal surface of each tooth was ground toexpose superficial dentin layer, and then dentin bonding agent was directly appliedonto freshly prepared dentin together with cylinder of 3M composite and light cured(group I, control group). Dentin surface pre-treated with zinc oxide eugenol temporaryfilling, then dentin bonding agent together with a cylinder of 3M composite (group II,single bonding technique). While in group III dentin bonding agent was applied firston the dentin surface and light cured, then zinc oxide eugenol temporary filling wasadded for one week, after removal of temporary filling dentin bonding agent togetherwith 3M composite was applied and light cured (dual bonding technique). The shearbond strength of all the specimens was determined using Zwick universal testingmachine. The results showed that all temporary filling treated groups (II and III) hadlower mean shear bond strength compared to control group (group I), whereascompared to single bonding technique, dual bonding technique significantly increasedthe shear bond strength.

Microleakage and Shear Bond Strength of Composite Restorations Under Cycling Conditions.

The aim of this study was to evaluate microleakage and shear bond strength of composite restorations under different cycling conditions. Class V cavities were prepared in the buccal and lingual surfaces of 30 human molars (n=60). A further 60 molars were used to prepare flat enamel and dentin specimens (n=60 each). Cavities and specimens were divided into six groups and pretreated with an adhesive (self-etch/Clearfil SE Bond or etch-and-rinse/Optibond FL). Composite was inserted in the cavities or adhered to the specimens' surfaces, respectively, and submitted to cycling (control: no cycling; thermal cycling: 10,000 cycles, 5°C to 55°C; thermal/erosive cycling: thermal cycling plus storage in hydrochloric acid pH 2.1, 5 minutes, 6×/day, 8 days). Microleakage was quantified by stereomicroscopy in enamel and dentin margins after immersion in silver nitrate. Specimens were submitted to shear bond strength testing. Statistical analysis was done by two-way analysis of variance and Kruskal-Wallis tests (p<0.05). Microleakage in enamel margins was significantly lower in the control group compared with thermal cycling or thermal/erosive cycling. Erosive conditions increased microleakage compared with thermal cycling (significant only for Clearfil SE Bond). No significant differences were observed in dentin margins. Bond strength of enamel specimens was reduced by thermal cycling and thermal/erosive cycling when Clearfil SE Bond was used and only by thermal/erosive cycling when Optibond FL was used. No differences were observed among dentin specimens. Thermal/erosive cycling can adversely affect microleakage and shear bond strength of composite resin bonded to enamel.

Influence of pH cycling and mechanical loading on the resin-dentin microtensile bond strength

The durability of adhesive interfaces is still a problem in adhesive restorations in dentistry. Laboratorial ageing methods have been proposed to predict the performance of materials, but they still require standardization. The objective of this study was to evaluate the resin-dentin microtensile bond strength of composite restorations subjected to pH cycling and different levels of mechanical loading. Resin blocks were built over a flat superficial dentin of bovine incisors (n = 40), using a three-step adhesive system. Half of the specimens were submitted to 10 cycles of pH cycling, followed by mechanical loading (0, 500,000; 1,000,000; 2,000,000 cycles – 98 N, 4 Hz). The other half was directly subjected to mechanical loading. After ageing, all groups were subjected to a microtensile bond test. Data were analyzed using two-way ANOVA and Tukey’s test (α = 0.05). The frequency of the early de-bonding was compared using the Chi-square test (α = 0.05). The statistical analysis revealed that the cross-product interaction ‘pH cycling’ vs. ‘number of mechanical loading cycles’ (p = 0.72) as well as the main factor ‘pH cycling’ (p = 0.49) was not statistically significant, and they were not able to reduce the resin–dentin bond strength values. Regarding the number of mechanical loading cycles, the groups subjected to 2,000,000 cycles showed lower bond strength values than the others (p = 0.003). The frequency of debonded specimens increased with mechanical loading. Therefore, it can be concluded that in this restorative model, at least 2,000,000 mechanical cycles are need to decrease the microtensile strength and simulate the ageing of the interface.

Effect of different desensitizing adhesive systems on the shear bond strength of composite resin to dentin surface

Objective The aim of this study was to evaluate the effect of different desensitizing agents, oxalate desensitizer and I-Bond, on the shear bond strength of composite resin to dentin surface. Materials and methods Occlusal surfaces of 80 sound human molars extracted were trimmed to expose a flat dentin surface. Each prepared sample was inserted in a metallic mold, which was designed with a Teflon mold having a hole (4 mm diameter ×3 mm height) for filling the restorative material. The samples were divided into four groups (20 each): group I (the control group), in which Adper Single Bond 2 and composite were applied; group II, in which oxalate desensitizer (D/Sense Crystal) was applied followed by Adper Single Bond 2 and composite; group III, in which oxalate desensitizer was applied, followed by re-etching and application of Adper Single Bond 2 and composite; and group IV, in which I-Bond and composite were used. All samples were thermocycled for 500 cycles (5–55°C). The samples in each group were subdivided into two subgroups (10 each) (A and B) according to storage time (24 h or 6 months, respectively). Shear bond strength of eight samples from each subgroup was measured. Debonded surfaces were examined under a stereomicroscope at magnification ×40 to determine the mode of failure. The remaining two samples were prepared to be examined under scanning electron microscope to reveal the resin penetration. Results Group I (the control group) recorded the highest shear bond strength values (11.838 ± 3.141 and 6.842 ± 3.912, respectively) in the two subgroups, followed by group IV (6.695 ± 3.164 and 6.217 ± 3.276, respectively) and group III (7.707 ± 3.845 and 3.681 ± 1.743, respectively), whereas the lowest values were found in group II (6.347 ± 3.208 and 3.240 ± 1.804, respectively). The incidence of adhesive mode of failure was higher in all tested groups, followed by mixed mode. Scanning electron microscope results confirmed the obtained statistical analysis of collected data. Clinical significance Both desensitizing agents and storage time had a negative significant effect on the shear bond strength of composite restoration to dentin surface.

Comparison of Shear Bond Strength of Composite Restoration to Intact Enamel of Primary Incisors using Different Conditioners, and Adhesive Systems

Background: Esthetic demands among patients have led to the introduction of tooth-colored restorations. Composite resins bond to enamel applying acid etch technique. Total etch adhesion systems are still considered as golden standard among bonding systems. However, clinicians have tendency towards using adhesive systems with a simplified application procedure. The aim of the present study is to compare the shear-bond strength of composite restoration to intact enamel of primary incisors using different conditioners, and adhesive systems.&#x0D; Materials and Methods: This experimental study was conducted in Shiraz University of Medical Sciences. 53 teeth were classified into 5 groups based on the bonding procedure. After composite build-up, specimens were placed in a universal testing machine at a cross-head speed of 1mm/min. Inter-group comparison of the shear-bond strength to enamel was analyzed employing One-way-ANOVA and Tukey post-hoc test. Data were statistically analyzed using SPSS (Version 17, Chicago, IL, USA).&#x0D; Results: The highest shear-bond strength was related to the second (37% phosphoric acid etching + Margin Bond adhesive system), and the fifth group (37% phosphoric acid etch + Tokuyama Bond Force adhesive system), and the lowest bond strength was related to the third group (Tokuyama Bond Force adhesive system alone) (p value = 0.00).&#x0D; Conclusion: Based on the results of the present study, surface pre-treatment with 37% PA accompanied with self-etching adhesive system, increased the shear-bond strength in vitro. This method can be further studied in clinical settings.

Effect of thermal cycling on micro-tensile bond strength of composite restorations bonded with multimode adhesive

Objective: The purpose of this in vitro study was to evaluate the effect of thermal cycling on the micro-tensile bond strength (Mtbs) of multimode adhesive agents. Materials and methods: Eight freshly extracted caries-free human third molars were used. The flat dentin surfaces were prepared and polished with 600-grit SiC abrasive paper for standard smear layer formation. The teeth were restored using Single Bond Universal Adhesive [(total etch (G1, G2)/self etch (G3, G4)] + Filtek Z550 and All-Bond Universal Adhesive [(total etch (G5, G6)/self etch (G7, G8)] + Aelite all-purpose. The specimens in groups G1, G3, G5, and G7 were subjected to thermal cycling (1000 cycles at 5–55 °C, for a 30 s dwell time), while the specimens in other groups were not exposed to an aging procedure. The Mtbs test was determined in all procedures. Data were submitted to three-way ANOVA and post hoc tests. The significance level was set at = 0.05. Results: Group five was highly affected by the thermal cycling following the total etch procedure, while group one was not significantly affected. Group seven was highly affected by thermal cycling, while group three was not significantly affected after the self etch procedure. Group eight exhibited a higher mean Mtbs value after the thermal cycling procedure. Conclusion: The bond strength of multimode (universal) adhesives was found to be material dependent. The total etch procedure showed a higher Mtbs value than the self etch procedure.