Effect of dentin biomodification techniques on the stability of the bonded interface.

AIM: The aim of this study is to evaluate the effect of different bonding techniques ethanol wet bonding and dimethyl sulfoxide (DMSO) wet bonding and a novel collagen cross-linker Quercetin application on the durability of resin-dentin bond and observe the bonded interface under the scanning electron microscope (SEM). MATERIALS AND METHODS: For shear bond strength testing, flat coronal dentin surfaces were prepared on 110 extracted human molars. Teeth were randomly divided into five experimental groups according to different surface pretreatments techniques. Group A was control group without any surface pretreatment. In Group B, ethanol wet bonding pretreatment was done before the application of adhesive. In Group C, DMSO wet bonding was done before the application of adhesive and in Groups D and E, Quercetin along with ethanol and Quercetin along with DMSO pretreatment, respectively, were done before adhesive application. Composite restorations were placed in all the samples. Twenty samples from each group were subjected to immediate and delayed (9 months) shear bond strength evaluation. In addition, two samples per group were subjected to the scanning electron microscopic analysis for the observation of resin-dentin interface. STATISTICAL ANALYSIS: Data collected were subjected to the statistical analysis using the one-way analysis of variance and post hoc Tukey's test at a significance level of P < 0.05. RESULTS: Dentin pretreatment with all the techniques resulted in significantly higher resin-dentin bond strength after 9 months storage with DMSO group showing the highest bond strength values. CONCLUSION: It can be concluded that these biomodification techniques can improve the durability of the resin-dentin bond.

Comparative evaluation of effect of chlorhexidine, Azadirachta indica (neem), and Aloe barbadensis miller (Aloe vera) on resin-dentin bond stabilization using shear bond testing: An in vitro study.

INTRODUCTION: Cavity disinfectants help to remove the microbial remnants; hence, its use prior to any restoration is valuable, and a search for alternative to chlorhexidine (CHX) is required which may be more efficacious and can overcome the drawbacks of CHX. OBJECTIVE: The aim of this study was to evaluate the effect of application of three different cavity disinfectants in a clinically relevant time period on the immediate and delayed shear bond strengths (SBSs) of an etch-and-rinse adhesive system to dentin. MATERIALS AND METHODS: For SBS testing, flat coronal dentin surfaces were prepared in two hundred extracted human molars. Specimens were randomly assigned to four groups according to the disinfectant used: Group I: Control (no disinfectant), Group II: 2% CHX solution, Group III: Aloe barbadensis miller (Aloe vera) solution, and Group IV: Azadirachta indica (neem) solution. Specimens were bonded using Prime and Bond NT adhesive which was employed according to the manufacturer's instructions. Resin composite cylinder buildups were done in all the samples. The modes of failure were noted after visual examination using a binocular stereomicroscope. Samples were also analyzed under scanning electron microscope for observation of resin-dentin interface. SBS results were analyzed using one-way ANOVA followed by Tukey's post hoc test. RESULTS: The results showed that CHX, Aloe vera, and neem had improved bond strengths as compared to the control group for both immediate and delayed SBSs. CONCLUSION: From the results of the study, the authors concluded that Aloe vera and neem can be used as alternative cavity disinfectants to CHX.

Comparative evaluation of the effect of different disinfecting agents on bond strength of composite resin to dentin using two-step self-etch and etch and rinse bonding systems: An in-vitro study.

OBJECTIVE: This study was carried out to examine the effect of the application of different disinfecting agents on the shear bond strength (SBS) of an etch-and-rinse system. MATERIALS AND METHODS: A total of 120 dentin surfaces of human molars were taken. Sixty samples were taken for immediate (testing was done after 24 h) and delayed (testing was done after 6 months) each. Further, they were divided into three subgroups (n = 20) according to the disinfectant used: Group I: control (no disinfectant); Group II: chlorhexidine based; and Group III: Aloe barbadensis miller (Aloe vera) based. Dentine bonding agent was applied, and resin composite build-ups were done for SBS testing. Samples were examined under scanning electron microscope for observing the gap formation for dentin-restoration interface. SBS results were statistically analyzed. RESULTS: The results of the study showed that both chlorhexidine and aloe vera had improved bond strength as compared to the control group both for immediate and delayed SBSs. CONCLUSION: Thus, aloe vera can be used as an alternative to chlorhexidine for cavity disinfection.

Evaluation of antibacterial efficacy of Chitosan, Chlorhexidine, Propolis and Sodium hypochlorite on Enterococcus faecalis biofilm : An in vitro study.

BACKGROUND: Long term successful root canal treatment requires effective debridement and disinfection of root canal system. Persistent periradicular lesions are usually associated with Enterococccus faecalis. Prompt research for natural alternatives for irrigation is mainly due to the constant increase in antibiotic resistant strains and side effects caused by synthetic drugs. Sodium hypochlorite; the gold standard for irrigation has many disadvantages. Therefore, the present study was aimed to explore newer irrigants probably be as more effective and at the same time would be less irritating to the tissues than NaOCl. MATERIAL AND METHODS: Ninety extracted human mandibular premolars were biomechanically prepared, vertically sectioned, placed in tissue culture wells exposing the root canal surface to E. faecalis to form a biofilm. At the end of 3rd week, all groups were irrigated with 3 ml of test solutions and control for 10 minutes. The samples were then scraped with a scalpel, inoculated on tryptone soy agar plates and incubated for 24 hours at 37ºC. The plates were then subjected to digital colony counter and evaluated for E. faecalisgrowth. The growth was statistically analysed by ANOVA & Post Hoc Tukey tests. RESULTS: Chitosan + Chlorhexidine, NaOCl and Chlorhexidine showed no statistically significant difference, whereas all the other inter­group differences were statistically significant (P<0.05). CONCLUSIONS: Chitosan + Chlorhexidine, Chlorhexidine and Propolis were found to be as efficacious as sodium hypochlorite. The use of natural alternatives as root canal irrigation solutions might prove to be advantageous considering several unfavorable properties of NaOCl. Key words:Antibacterial efficacy, Chitosan, Enterococcus faecalis, Root canal irrigation.

Effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin.

OBJECTIVES: This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. MATERIALS AND METHODS: Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups (n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio­Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. RESULTS: At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only (p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resin-dentin bond strength with no significant fall. CONCLUSIONS: Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

Effect of carbodiimide on the structural stability of resin/dentin interface.

Clinical longevity of composite resin restorations is a significant problem in adhesive dentistry. Most of the current simplified adhesives present good immediate bonding, but the bond strength gradually falls over a period due to biodegradation at the resin-dentin interface. Various strategies have been proposed to improve the durability of resin-dentin bond including the use of matrix metalloproteinases inhibitors and collagen cross-linkers, biomimetic remineralization, ethanol wet bonding, to improve the physical and mechanical properties of the bonding substrate, i.e., dentin. However, all are under preliminary research and without any conclusive evidence. Therefore, this paper addresses the current challenge in dental adhesion, i.e., poor durability of resin-dentin bond and introduces the concept of dentin biomodification as an alternative way for improving the long-term bonding effectiveness of current adhesives to dentin and also provides an overview of a synthetic collagen cross-linking agent carbodiimide (EDC) including its mechanism of action, literature review of studies evaluating EDC, variables associated with its use and its cytotoxicity. Search was performed across the electronic databases (PubMed, Ebsco host, and Google search engine) to identify manuscripts for inclusion, using the keywords: carbodiimide, dentin bonding, durability, resin-dentin interface, and collagen cross-linking. Thirty-five articles were finally included, and the last search was made in February 2016.

The shear bond strength of MTA with three different types of adhesive systems: An in vitro study.

AIM: To evaluate the shear bond strength of MTA with three different types of adhesive systems- self-adhering flowable composite, etch and rinse adhesive system and self etch adhesive system. METHODOLOGY: MTA specimens (n = 60) were prepared using cylindrical acrylic blocks, having a central cavity with 4 mm diameter and 2 mm depth. MTA was mixed and placed in the prepared cavity, and was covered with a moist cotton pellet and temporary filling material. The specimens were divided into 3 groups which were further divided into 2 sub-groups (45 Minutes and 24 hours). After the application of bonding agents composite resin was placed over the MTA surface. The specimens were tested for shear bond strength and readings were statically analyzed. RESULT: After 24 hrs the mean value of etch and rinse group was significantly higher than self etch and the self adhering composite groups. Among the 45 minutes groups there were no significant difference. CONCLUSION: In single visit after 45 minutes self adhering flowable can be used successfully as a final restorative material in place of conventional flowable composite without using any alternative adhesive system over MTA.

Influence of double application technique on the bonding effectiveness of self-etch adhesive systems.

AIM: To evaluate and compare the effect of double-application of single-step self-etch adhesives using microleakage study and to analyze the dentin-adhesive interfacial micromorphology. METHODS: In total, 72 extracted human premolars were divided into three groups for different self-etch adhesives (G Bond, GC [GB], Optibond, Kerr [OB], and Xeno V Plus, Dentsply [XV]). Class V cavities were prepared. Each group was further divided into two subgroups (n = 10) according to the placement technique of the adhesive, using the single-application [subgroup (a)] or double-application method [subgroup (b)]. Resin composite (Z 250, 3M ESPE, St. Paul, MN) was used to restore the cavities and light cured for 40 s. Twenty samples from each group were subjected to microleakage study. Two samples from both the subgroups of the three adhesives were used for scanning electron microscopic examination of the resin-dentin interfacial ultrastructure. Dye leakage scores were subjected to statistical analysis using Kruskal-Wallis and Mann-Whitney U-tests at significance level of P < 0.05. RESULTS: GB depicted significantly more microleakage which was significantly greater than OB and XV. The double application led to significant decrease in microleakage of GB with no significant effect on the microleakage scores of other two all-in-one adhesives, that is OB and XV. CONCLUSION: Double application of all-in-one self-etch adhesives improves the marginal sealing ability in dentin although it appears to be product dependent.

Influence of cervical preflaring using different rotary instruments on the accuracy of apical file size determination: A comparative in-vitro study.

AIM: To investigate the influence of cervical preflaring using different rotary instruments on apical file size determination. MATERIALS AND METHODS: Extracted human molar teeth were randomly divided in to eight groups (N = 10): Control group (CG); LA Axxess group (LA); HyFLex group (HF); GatesGlidden group (GG); ProTaper group (PT); Race group(RC); FlexMaster group (FM); and K3 group (K3). Patency was maintained and working length was established under magnification. All instruments were used according to manufacturer's instructions. Steriomicroscopic images were taken to determine the discrepancies in diameters. ProPlus software (USA) was used to determine the diameter of the root canal. ANOVA test and Post Hoc Tests-Bonferroni Multiple Comparisons were used for statistical analysis. RESULTS: Canals preflared with LA Axxess burs showed the best results. Control group that is, the canals with no cervical preflaring showed the maximum discrepancy between the initial apical file diameter and apical canal diameter. CONCLUSION: Cervical preflaring plays an important role in reducing the discrepancy between initial apical file diameter and apical canal diameter.

In vitro bonding effectiveness of three different one-step self-etch adhesives with additional enamel etching.

AIM: To evaluate the effect of additional enamel etching on the shear bond strength of three self-etch adhesives. METHODS: Class II box type cavities were made on extracted human molars. Teeth were randomly divided into one control group of etch and rinse adhesive and three test groups of self-etch adhesives (Clearfil S3 Bond, Futurabond NR, Xeno V). The teeth in the control group (n = 10) were treated with Adper™ Single Bond 2. The three test groups were further divided into two subgroups (n = 10): (i) self-etch adhesive was applied as per the manufacturer's instructions; (ii) additional etching of enamel surfaces was done prior to the application of self-etch adhesives. All cavities were restored with Filtek Z250. After thermocycling, shear bond strength was evaluated using a Universal testing machine. Data were analyzed using anova independent sample's 't' test and Dunnett's test. The failure modes were evaluated with a stereomicroscope at a magnification of 10×. RESULTS: Additional phosphoric acid etching of the enamel surface prior to the application of the adhesive system significantly increased the shear bond strength of all the examined self-etch adhesives. CONCLUSIONS: Additional phosphoric acid etching of enamel surface significantly improved the shear bond strength.

Comparison of antimicrobial efficacy of propolis, Morinda citrifolia, Azadirachta indica (Neem) and 5% sodium hypochlorite on Candida albicans biofilm formed on tooth substrate: An in-vitro study.

INTRODUCTION: Endodontic infections are polymicrobial in nature. Candida albicans is the most common fungus isolated from failed endodontic cases. The constant increase in antibiotic resistant strains and side-effects caused by synthetic drugs has prompted researchers to look for herbal alternatives such as propolis, Morinda citrifolia and Azadirachta indica (Neem) etc., since, the gold standard for irrigation, i.e., sodium hypochlorite has many disadvantages. MATERIALS AND METHODS: Extracted human mandibular premolars were biomechanically prepared, vertically sectioned, placed in tissue culture wells exposing the root canal surface to C. albicans grown on Sabouraud Dextrose Agar to form a biofilm. At the end of 2 days, all groups were treated with test solutions and control for 10 min and evaluated for Candida growth and number of colony forming units. The readings were subjected to statistical analysis using analysis of variance and post hoc Tukey tests. RESULTS: Sodium hypochlorite and propolis groups exhibited highest antimicrobial efficacy against C. albicans with no statistically significant difference. It was followed by the A. indica (Neem) group. M. citrifolia had limited antifungal action followed by the negative control group of saline. CONCLUSION: According to the results of this study, propolis can be used as an effective antifungal agent similar to that of sodium hypochlorite, although long-term in vivo studies are warranted.

Long-term bonding effectiveness of simplified etch-and-rinse adhesives to dentin after different surface pre-treatments.

OBJECTIVE: To evaluate the effect of 2% chlorhexidine (CHX) and 30% proanthocyanidin (PA) application on the immediate and long-term bond strength of simplified etch-and-rinse adhesives to dentin. MATERIALS AND METHODS: One hundred twenty extracted human molar teeth were ground to expose the flat dentin surface. The teeth were equally divided into six groups according to the adhesives used, either Tetric N Bond or Solobond M and pretreatments given either none, CHX, or PA. Composite cylinder was bonded to each specimen using the respective adhesive technique. Half the samples from each group (n = 10) were then tested immediately. The remaining samples were tested after 6 month storage in distilled water. RESULTS: The mean bond strength of samples was not significantly different upon immediate testing being in the range of 8.4(±0.7) MPa. The bond strength fell dramatically in the control specimens after 6 month storage to around 4.7(±0.33) MPa, while the bond strength was maintained in the samples treated with both CHX and PA. CONCLUSION: Thirty percent PA was comparable to 2% CHX with respect to preservation of the resin dentin bond over 6 months.

Effect of different root canal irrigants on the sealing ability of two all-in-one self-etch adhesives: An in vitro study.

AIM: To evaluate the effect of different root canal irrigants on the sealing ability of two self-etch adhesives, using dye penetration method, within the pulp chamber. MATERIALS AND METHODS: 72 extracted human molars were divided into six groups, according to the irrigant and self-etch adhesives used. After de-roofing the pulp chamber with a carborundum disc, the pulp was extirpated using excavator and broaches. In 36 samples, pulp chambers were bonded with Xeno V after irrigation with either 2% CHX (Group1: Xe-CHX) ; 17% EDTA + 5.25% NaOCl (Group2: Xe- EDTA + NaOCl) or normal saline (Group3: Xe-NS) and in other half samples, pulp chambers were bonded with Adper Easy One after irrigation with either 2% CHX (Group 4: Ad-CHX); 17%EDTA + 5.25% NaOCl (Group5: Ad-EDTA+NaOCl) or normal saline (Group 6: Ad-NS). All the samples were restored with Filtek Z350. Ten teeth from each group were assessed for dye penetration. Two samples in each group were viewed under scanning electron microscope to observe resin-dentin interfacial adaptation. Data was statistically analyzed using Mann-Whitney and Kruskal Wallis tests at a significance level of P < 0.05. RESULTS: MEAN MICROLEAKAGE SCORES AND STANDARD DEVIATION OBSERVED WERE: Group 1 (Xe-CHX): 2.8 ± 0.42, Group 2 (Xe-EDTA + NaOCl): 2.3 ± 0.82, Group 3 (Xe-NS): 2.9 ± 0.31, Group 4 (Ad-CHX): 1.2 ± 0.91, Group 5 (Ad-EDTA + NaOCl): 0.8 ± 0.63, Group 6 (Ad-NS): 1.9 ± 0.99. CONCLUSIONS: Adper Easy One showed significantly less leakage than Xeno V when normal saline was used as an irrigant. EDTA treatment followed by NaOCl application significantly reduced microleakage and improved the interfacial adaptation with Adper Easy One. CHX did not significantly affect the sealing ability of both one-step self-etch adhesives tested.

In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study.

AIM: To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin-dentin interfacial ultrastructure under scanning electron microscope (SEM). MATERIALS AND METHODS: 100 extracted human premolars were divided into two groups for different adhesives (Clearfil S(3) and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin-dentin interface. RESULTS: At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin-dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied. CONCLUSIONS: In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage.

Contribution of CNS cells in NeuroAIDS.

NeuroAIDS is becoming a major health problem among AIDS patients and long-term HIV survivors. As per 2009 estimates of UNAIDS report, more than 34 million people have been infected with HIV out of which ≥ 50% show signs and symptoms of neuropsychiatric disorders. These disorders affect central nervous system (CNS) and peripheral nervous systems (PNS). CNS is one of the most protected organ systems in body which is protected by blood-brain barrier (BBB). Not only this, most of the cells of CNS are negative for receptors and co-receptors for HIV infections. Neurons have been found to be completely nonpermissive for HIV infection. These facts suggest that neurotoxicity could be an indirect mechanism responsible for neuropsychiatric complications. In this review, we will discuss the importance of different cell types of CNS and their contribution toward neurotoxicity.

DNA cleavage study using copper (II)-GlyAibHis: a tripeptide complex based on ATCUN peptide motifs.

Development of new chemical nucleases is a matter of great interest because of their extensive use in biotechnology and as therapeutic agents. The ATCUN (amino terminal Cu(II) and Ni(II) binding) is a peptide motif that occurs naturally in the serum albumins. The similar peptide motif (GlyAibHis) having unnatural amino acid Aib (alpha-aminoisobutyric acid) was synthesized and its Cu(II) complex was characterized by ESI-MS and spectrophotometry studies. The reactivity of this complex toward DNA cleavage has been investigated. Cu(II)-GlyAibHis shows the DNA cleavage only in presence of mild oxidizing agents like ascorbate by an oxidative mechanism rather than hydrolytic and follows the pseudo first order kinetics (K obs = 0.085 min(-1)). The non-hydrolytic mechanism was further supported by the hydrolysis of pNPP which followed the pseudo first order kinetics (K obs = 1.98 x 10(-2) min(-1)) having no pH effect.

Expression and cellular pattern of relaxin mRNA in porcine corpora lutea during pregnancy.

We developed an in situ hybridization method for detecting relaxin mRNA in the porcine corpus luteum (CL) by employing a non-radioactive probe and microwave fixation. We subsequently examined the expression and cellular patterns of relaxin mRNA in the CL during pregnancy and then evaluated whether relaxin mRNA was a factor limiting hormone production by the CL. Digoxigenin (DIG)-labeled RNA probes complementary to porcine relaxin mRNA were produced by in vitro transcription. The specificity was validated by showing, by Northern analysis, that the anti-sense probe hybridized to a 1.0-kb relaxin transcript in the CL. Microwave fixation (2-min irradiation in a conventional microwave oven) combined with DIG-labeled cRNA probes allowed precise and reliable analysis of relaxin mRNA, with superior retention of the mRNA and a higher resolving power. Application of this method to the porcine CL during pregnancy demonstrated that the relaxin mRNA level per cell and the percentage of mRNA-expressing cells increased as gestation progressed, with a marked decline near term. Northern analysis revealed the cellular pattern of relaxin mRNA localization, showing that the increase of relaxin mRNA with advancing pregnancy was attributable to an increase of both the cellular mRNA level and the percentage of mRNA-expressing cells. The present findings, taken together with known relaxin levels in the CL, reveal that changes of relaxin mRNA are correlated with changes of the hormone in the CL during pregnancy, suggesting that the relaxin level is determined by the amount of mRNA available for translation.

Neem in human and plant disease therapy.

As a therapeutic agent, neem is one of the most popular trees in traditional medicinal systems and is increasingly becoming important in herbal alternative therapy. The tree itself is considered a "village pharmacy" because of the well-established fact that every part of the tree has an application in curing human diseases. The tree has been a constant source of novel and structurally unique phytochemicals that can constitute the basis for the development of novel pharmaco-therapeutic agents against various human diseases. Being a prototype for the development of safer drugs and ecofriendly, pro-human health agrochemical agents against a vast variety of plant diseases, the tree always remains in the center of safe herbal drug and pesticide development in the service of mankind.