Dentin-bonding Agents Research Articles

Flexural strength of dental adhesives with different photoinitiator systems.

The aim of this study was to investigate the flexural strength of dental adhesives containing different combinations of photoinitiators systems. The organic matrix of the experimental adhesives was created using a blend of monomers: 50% by weight bisphenol-A glycidyl methacrylate (BisGMA) and 50% triethylene glycol dimethacrylate (TEGDMA). The photoinitiators utilized were camphorquinone (CQ) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), with diphenyliodonium hexafluorophosphate (DPIHFP) and 2-(Dimethylamino)ethyl methacrylate (DMAEMA) as co-initiators. These photoinitiators and co-initiators were integrated into the organic matrix at a concentration of 0.5% by mass, resulting in the formation of 6 groups (n=12): CQ/DMAEMA (control); CQ/DMAEMA/DPIHFP; BAPO; BAPO/DMAEMA; BAPO/DPIHFP and BAPO/DMAEMA/DPIHFP. Samples measuring 7 mm in length, 2 mm in width, and 1 mm in height were prepared and subjected to a three-point flexural test. Data were analyzed using one-way ANOVA with Tukey's post-hoc test (α=0.05). Results indicated that groups incorporating BAPO and DPIHFP exhibited higher flexural strength compared to those with CQ and DMAEMA. The BAPO/DPIHFP group achieved the highest mean flexural strength values (p<0.001). These findings suggest that using adhesive systems with alternative photoinitiators and co-initiators can lead to superior flexural strength compared to conventional systems. Key words:Photoinitiators, Dentin-bonding agents, Light-curing.

Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study.

The purpose of this study was to evaluate the effectiveness and strength of three various dentin-bonding agents used with adhesives on primary teeth. The study used 80 recently extracted, healthy human maxillary anterior primary teeth that had undergone physiologic resorption, or over-retention. Teeth were cut to expose a flat dentin surface at a depth of 1.5 mm. All samples were divided into four groups (20 samples in each group) as follows: Group I-Control group, Group II-Primary teeth bonding with 6th-generation bonding agent, Group III-Primary teeth bonding with 7th-generation bonding agent, Group IV-Primary teeth bonding with 8th-generation bonding agent. All of the samples' dentinal surfaces were covered with composite resin using a Teflon mold after adhesive had been applied. A universal testing machine (INSTRON) was used to assess the shear bond strength. Data were collected and statistically analyzed. The maximum mean shear bond strength was found in 8th-generation bonding agent (30.76 ± 0.16), followed by 7th-generation bonding agent (26.08 ± 0.21), 6th-generation bonding agent (25.32 ± 0.06), and control group (6.18 ± 0.09). Statistically significant difference was found between the three different bonding agents (p < 0.001). On conclusion, the 8th-generation bonding agent demonstrated a greater shear bond strength to dentin than the 7th and 6th-generation bonding agent. The emergence of different bonding techniques to the market improves the durability and quality of restorations. An effective bonding to the tooth would also reduce bacterial penetration, marginal microleakage, possibility of pulpal inflammation preserve tooth structure, and postoperative sensitivity by allowing less cavity preparation. How to cite this article: Alqarni AS, Al Ghwainem A. Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study. J Contemp Dent Pract 2024;25(4):342-345.

Comparative Analysis of Techniques for Pit and Fissure Sealant Application to Reduce Microleakage.

Introduction In modern dentistry, the focus is more on preventing caries than on treating it, which helps preserve the tooth structure. Pit and fissure sealants (PFS) are the most effective methods for providing a mechanical barrier and avoiding the accumulation of dental plaque in deep pits and fissures, thereby preventing occlusal caries. The present study was conducted to compare the efficiency of dentin bonding agents (DBA) with or without fissurotomy in reducing microleakage before PFS placement. Materials and methods A total of 48 freshly extracted premolars were randomly divided into four groups as follows: Group 1, the conventional technique of PFS (Clinpro, 3M ESPE sealant); Group 2, fissurotomy performed before PFS placement; Group 3, Scotchbond Universal Adhesive (3M ESPE DBA) applied before PFS placement; and Group 4, fissurotomy along with DBA was used before PFS placement. The teeth were subjected to thermocycling followed by dye penetration using a 1% solution of methylene blue for 24 hours. All teeth were then assessed for microleakage by a qualitative method using a stereomicroscope at 40X and depth of dye penetration by image analysis. The Kruskal-Wallis test followed by Dunn's test was used for intergroup comparisons of microleakage scores, and ANOVAfollowed by Tukey's test was used for intergroup comparisons of the depth of dye penetration. These analyses were conducted using statistical software (SPSS version 22, Chicago, IL, USA). Results Statistically significant differences were observed between the groups in terms of the microleakage scores and depth of dye penetration (p<0.05). The group 4 showed a minimum microleakage score (0.50±0.52), and maximum scores were observed in Group 1 (2.16±0.71). Group 2 showed insignificant differences with groups 3 and 4 for depth of dye penetration (p>0.05). Statistically significant differences were observed between groups 1 and 2, groups 1 and 4, and groups 3 and 4 for the microleakage score (p<0.05). Conclusion Fissurotomy with or without DBA significantly reduced microleakage before the PFS placement. Prior use of fourth-generation DBA significantly reduced microleakage compared with PFS placement without the use of DBA.

The Efficacy of Different Laser Applications on Dentin Sealing in Preventing Discoloration Induced by Mineral Trioxide Aggregate.

The aim of this in vitro study was to evaluate the effect of the pre-application of a dentin-bonding agent and the application of different lasers on the prevention of tooth discoloration caused by mineral trioxide aggregate (MTA) in the presence of blood. Sixty extracted human anterior teeth were selected, with root lengths standardized to 10 mm and root canals shaped using Gates-Glidden drills #3 to #5. The samples were divided into six groups (n = 10): Group 1 with no surface treatment and Groups 2 to 6 with Optibond universal adhesive and Neodymium yttrium aluminum garnet (Nd:YAG), Erbium yttrium aluminum garnet (Er:YAG), Erbium-chromium-yttrium-scandium-gallium-garnet (Er:Cr:YSGG), and diode laser applications, respectively. Root canals were filled with fresh human blood, and ProRoot MTA and a collagen barrier were then placed. Color changes were measured with a spectrophotometer at 0, 7, 30, 90, and 180 days post MTA placement. Color differences (∆E) were analyzed using a two-factor mixed-design ANOVA with the Sidak method (p = 0.05). All treatment groups exhibited discoloration above the acceptability threshold. Although all treatment approaches exhibited less color change compared to the control group (p < 0.05), there was no significant difference among them in terms of preventing color change (p > 0.05). It was determined that none of the methods could guarantee 100% prevention of discoloration caused by MTA-blood contact.

Spectrophotometric analysis of the effectiveness of different dentin tubule occlusion techniques in preventing discoloration caused by photosensitizers used in photodynamic therapy

AimThe efficacy of Copal Varnish (CV), dentin bonding agent (DBA), Nd:YAG laser and Er:YAG laser, which occludes dentin tubules by different mechanisms, was investigated in order to prevent unwanted coloration caused by methylene blue (MB) and phthalocyanine used in photodynamic therapy (PDT). Materials and methods165 upper incisors included in the study. Root canals were prepared up to 30/0.6 size for all teeth using Protaper Next rotary files. Then the teeth were randomly divided into 2 main groups (n = 60); MB and phthalocyanine. Each main group was randomly divided into 5 subgroups (n = 15); Positive control, DBA, CV, Er:YAG and Nd:YAG. Root canals were filled with photosensitizers (PS) and activated after the dentin tubule occlusion method was applied to all teeth. Then, the residual PSs were removed by irrigation. Color measurements of the samples were carried out 5 different time periods. ResultsClinically detectable color change was observed in all groups except for the negative control (ΔE≥3.3). It was determined that the positive control using MB caused more unwanted coloration in the CV on the 30th and 90th days compared to the phthalocyanine used in the 90th day (p < 0.05). While none of the dentin tubule occlusion methods were superior to each other in preventing undesirable coloration caused by phthalocyanine, Er:YAG caused less unwanetd coloration than CV only on the 90th day in preventing unwanted coloration caused by MB (p < 0.05). ConclusionsAll dentin tubule occlusion methods used in the present study were effective in preventing some degree of unwanted discoloration. However, it was found that no technique could completely prevent unwanted coloration.

Complimentary Staining of Caries Detector Dyes in Primary Teeth with or without the Application of a Dentine Bonding Agent

Background: Caries detector dyes are introduced to aid in identifying infected dentine. Many researchers claim that they are not specific in identifying infected dentine since dyes also stains sound tooth surfaces. The use of a dentine bonding agent could help in avoiding the penetration of caries detector dyes to some extent in less mineralized primary teeth. This study assesses caries detector dyes penetration in primary teeth with or without dentine bonding agent application. Methodology: Ninety primary extracted carious teeth were considered for the study. Teeth were divided in to two groups (45 teeth each group): group I with dye application without dentine bonding agent and group II with dye application after dentine bonding agent; in both groups three different types of dyes were used. All cavity walls and surfaces of samples in group 1 were stained with caries detector dyes for 10 s, subsequently washed with water for another 10 s and finally air-dried. A similar procedure was carried for teeth in group II after the application of a bonding agent on visibly sound tooth surfaces without the use of an etchant. Results: A statistically significant difference between two groups for staining of different tooth surfaces was noted. A Kruskal–Wallis one-way ANOVA revealed a statistically significant difference in stain removal among the different groups either by distilled water or sodium hypochlorite were observed. Conclusion: A dentine bonding agent can help in preventing caries detector dye penetration in noncarious tooth surfaces of deciduous teeth.

An in Vitro Study of the Effects of Different Dentin Bonding Agents on the Prevention of Tooth Discoloration and the Sealing Ability of Calcium Silicate-Based Cement in Regenerative Endodontic Procedures

This study aimed to compare the effects of applying different types of dentin bonding agents (DBAs) on tooth and on the sealing ability of CSC in regenerative endodontic procedures (REPs). Specimens were made from 120 human first premolars and categorized into the following groups based on the presence and the type of DBA: Group I, no bonding; Group II, One-Step; Group III, Clearfil SE Bond; and Group IV, Single Bond Universal. Subsequently, the groups were categorized into Subgroup a and Subgroup b, in which Endocem MTA® Premixed Regular and Biodentine were used, respectively. The CIE L*a*b* on the photos taken prior to TAP placement (S0), 1 week after TAP placement (S1), 2 weeks after TAP placement (S2), 4 weeks after TAP placement (S3) and 2 weeks after CSC placement (S4) was used to assess discoloration. The samples were submerged in a 2% methylene blue solution and magnified by 30 times under a stereomicroscope to assess microleakage. The application of DBA during REP reduced crown discoloration, while Biodentine showed minimal discoloration with or without DBA and regardless of the DBA type. Additionally, the application of DBA did not increase microleakage.

Evaluation of the effectiveness of different treatment approaches in preventing coronal discoloration caused by regenerative endodontic treatment.

This study aimed to evaluate the effectiveness of Teethmate desensitizer, a dentin bonding agent (DBA), Nd:YAG laser, and Er:YAG laser, which provides dentin tubule occlusion in the pulp chamber with different mechanisms, in preventing tooth discoloration due to regenerative endodontic treatment. One hundred five extracted maxillary human incisors with single roots and single canals were included in the study. The apical third of each tooth was resected below the enamel-cementum junction (CEJ) to obtain a standard root length as 10 ± 1mm. Root canal preparation was performed using the ProTaper Next files up to X5. Root canals were prepared with Gates Glidden (# 2-4) burs to simulate the immature root apex and an apical diameter of 1.1 ± 0.1mm was obtained. The teeth were randomly divided into 7 groups (n = 15): DBA, Teethmate, Nd:YAG, Er:YAG, Biodentine, Blood, and Negative Control. Relevant dentin tubule occlusion methods were applied to DBA, Teethmate, Nd:YAG, and Er:YAG groups. Following dentin tubule occlusion procedures, Biodentine was placed on the blood clot after filling the root canals with blood up to 4mm below the CEJ. No dentin tubule occlusion procedure was applied for Blood and Biodentine groups. Color measurement was performed with the spectrophotometer Vita Easyshade Advance before treatment, immediately after treatment, and at days 7, 30, and 90. Data were converted to L*a*b color values of Commission International de I'Eclairage (CIE L*a*b) and ΔE values were calculated. Two-way ANOVA and post hoc Tukey test (p = 0.05) were performed for statistical analysis. A clinically detectable color change was observed in all groups except for the negative control (ΔE ≥ 3,3). It was observed that Biodentine used alone has a potential for discoloration. It was determined that as the contact time with blood increased, tooth discoloration increased. However, no significant difference was found between dentin tubule occlusion methods in preventing color change (p > 0.05). It was determined that no dentin tubule occlusion method could 100% prevent discoloration caused by RET. DBA and Teethmate, which do not have a significant difference in terms of preventing color change, are considered to be suitable for dentin tubule occlusion due to their ease of application and low cost compared to Nd:YAG laser and Er:YAG laser.

Influence of the incorporation of titanium dioxide nanofibers net on bond strength and morphology of a total etching adhesive system.

The aim of this study was to evaluate the nanoleakage and microtensile bond strength (μTBS) of an ethanol based-adhesive containing Titanium dioxide (TiO2) nanofibers to dentin. TiO2 nanofiber was produced by electrospinning and it was inserted in an ethanol-based adhesive in 0.5, 1.5 and 2.5% by weight. The original adhesive did not receive nanofiber. The middle dentin was exposed by diamond saw under water-cooling and dentin was polished with wet 600-grit SiC abrasive paper. Resin composite build-ups were applied incrementally to the dentin after adhesive application. After storage in distilled water (24 hours/37°C) the teeth were sectioned perpendicularly to the bonded interface and sticks were obtained. Twenty-five sticks per group were tested by μTBS with a crosshead speed of 0.5mm/minute. The average values (MPa) obtained in each substrate were subjected to one-way ANOVA (α=0,05) with the tooth being considered the experimental unit. The nanoleakage pattern was observed in ten sticks per group and analyzed by Chi-square test (α=0,05). There was no difference in μTBS among the experimental groups. However, there was a statistically significant difference among 2.5 % nanofiber adhesive, 0.5 % nanofibers and control groups, (p=0,028) in relation to nanoleakage. TiO2 nanofibers in 2.5% of weight inserted in dental adhesive reduced the nanoleakage, but did not improve the μTBS to dentin. Key words:Dentin-bonding agents, nanoleakage, tensile bond strength.

Influência do adesivo autocondicionante na resistência de união em dentes submetidos à radiação

ABSTRACT This study aimed to conduct a literature review about the influence of self-etching adhesives on the bond strength of restorative procedures for irradiated teeth. The search for articles was carried out on six databases (PubMed, Scopus, Web of Science, Embase, LILACS, Cochrane). Gray literature (Google Scholar) and reference lists of included studies were evaluated. The keywords used were: “Radiotherapy” OR “Radiation Therapy” OR “Radiation Treatment” OR “Radiation Effects” OR “Radioterapia” OR “Terapia por radiação” OR “Tratamento por radiação” OR “Efeitos da Radiação” OR “Terapia por Radiación” OR “Tratamiento por Radiación” OR “Efectos de Radiación” AND “Dentin-Bonding agent” OR “Adesivos Dentinários” OR “Recubrimientos Dentinarios”. The inclusion criteria were laboratory and clinical studies, dissertations, literary and systematic reviews, and no time and language restrictions. Three hundred and eighteen studies were identified in the databases, 30 in the gray literature, and 5 from the reference list of included articles. 40 were excluded for being duplicates. After reading the title and abstract, 28 articles remained for complete analysis. In the end, 21 articles were included in this study. Self-etching could be a good option for irradiated teeth restorations. However, further clinical studies are needed.

Influence of different adhesion strategies on glass fiber post retention.

Failures in glass fiber post (GFP) retention may be associated with low adhesion achieved in root dentin. 55 single-rooted premolars were endodontically treated and distributed according to different adhesion strategies (n=11): G1: RelyX ARC (3M ESPE; etch-rinse strategy); G2: Relyx Ultimate (3M ESPE; etch-rinse strategy); G3: AllCem (FGM; etch-rinse strategy); G4: Relyx Ultimate (3M ESPE; self-etching strategy); G5: RelyX U200 (3M ESPE; self-adhesive strategy). For Bonding Strength (BS) analysis, the roots were sectioned in slices (1.0mm thickness) corresponding to each root third and submitted to push-out test. The type of failure was assessed by scanning electron microscopy (SEM). The highest BS averages were found in G2 and G3. However, in the middle and apical root thirds, G3 showed statistically similar results to G4 and G5. In the cervical and middle third, G1 was statistically similar to G4 and G5. The mixed type of failure was the most common in all groups. Self-etching (G4) and self-adhesive resin (G5) cements, showed similar BS results of immediate bonding in the cementation of GFP compared to conventional resin cements (G1, G2, G3). Key words:Dental Cements, Dentin-Bonding Agents, Post and Core Technique, Dental Bonding.

The Repair of Resin-Modified Glass Ionomers with Bulk-Fill Flowable and Packable Composites using the Eight-Generation and Universal Dentin Bonding Agents

Background: To investigate shear bond strength regarding the repair of resin-modified glass ionomers (RMGIs) with bulk-fill flowable and packable composites using eighth-generation and universal dentin bonding agents. Materials and Methods: One-hundred-fifty specimens were prepared using polymethylmethacrylate-resin injected into preformed cylinders. Inverted recessed holes with convergent walls 4 mm deep and 4 mm wide were created using Operative Friction Grip 330L and inverted diamond burs. These holes were used as reservoirs for RMGI II LC. The resulting RMGI specimens were roughened with medium coarse diamond burs and placed in distilled water for 24 hours at 37o C to remove debris. RMGI surfaces were etched with 37% phosphoric acid for 20 seconds, rinsed with copious water, and air-dried without desiccation. Each RMGI specimen was placed in an Ultradent bonding clamp in preparation for adding the tested material. Specimens were divided into 6 groups: (1) Bulk-fill flowable composite (BFF) no adhesive (control), (2) Packable composite (PC) no adhesive (control), (3) BFF + iBond, (4) BFF + Futurabond-DC, (5) PC + iBond, and (6) PC + Futurabond-DC. Shear bond Strength was determined using an Ultra Tester Machine. Results: The SBS among and between groups were statistically assessed with repeated measures multivariate analysis of variance (MANOVA). The Tukey honestly significant difference test with an alpha level of 0.05 was used for post-hoc testing. Repeated measures MANOVA indicated that there were important differences between groups (Wilk’s lambda, P &lt; 0.0001), with BFF + Futurabond-DC resulting in the highest SBS. Conclusion: The study indicates that BFF combined with eighth-generation dentin bonding adhesive is a reliable method for the repair of RMGIs.

Inducing cathepsin L expression/production, lysosomal activation, and autophagy of human dental pulp cells by dentin bonding agents, camphorquinone and BisGMA and the related mechanisms

Camphorquinone (CQ) and resin monomers are included in dentin bonding agents (DBAs) and composite resin to restore tooth defects due to abrasion, crown fracture, or dental caries. DBAs, CQ, and bisphenol A-glycidyl methacrylate (BisGMA) applications influence the biological activities of the dental pulp. The current investigation aimed to delineate the effect of DBAs, CQ, and BisGMA on cathepsin L production/expression, lysosomal activity, and autophagy induction in human dental pulp cells (HDPCs). HDPCs were exposed to DBAs, CQ, or BisGMA with/without inhibitors for 24 h. Enzyme-linked immunosorbent assay was employed to determine the cathepsin L level in culture medium. The cell layer was utilized to measure cell viability by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl -tetrazolium bromide (MTT) assay. Real-time PCR was used to evaluate the mRNA expression. Western blotting or immunofluorescent staining was used to study protein expression. Lysosomal density was evaluated by lysotracker red staining. We found that DBAs, CQ, and BisGMA stimulated cathepsin L mRNA, protein expression, and production in HDPCs. In addition, CQ and BisGMA induced lysosomal activity, Beclin1, ATG12, LC3B, Bax, and p53 expression in HDPCs, indicating the stimulation of autophagy. Glutathione (GSH) prevented CQ- and BisGMA-induced cytotoxicity. Moreover, E64d, cathepsin L inhibitor (two cathepsin inhibitors), and Pifithrin-α (a p53 inhibitor) showed little preventive effect toward CQ- and BisGMA-induced cytotoxicity. Autophagy inhibitors (NH4Cl, Lys05) mildly enhanced the CQ- and BisGMA-induced cytotoxicity. These results indicate that DBAs stimulated cathepsin L, possibly due to their content of CQ and BisGMA that may induce cathepsin L in HDPCs. CQ and BisGMA stimulated lysosomal activity, autophagy, and apoptosis, possibly via induction of Beclin 1, ATG12, LC-3B, Bax, and p53 expression. In addition, CQ and BisGMA cytotoxicity was related to redox change and autophagy. These events are important role in pulpal changes after the restoration of tooth decay using CQ- and BisGMA-containing DBAs and resin composite.

Evaluation of push-out bond strength of different concentrations of chitosan nanoparticles incorporated composite resin and eighth-generation bonding agent for class II restoration: An in vitro study.

The aim of this study is to evaluate the push-out bonding strength of class II cavities of maxillary molars restored with different concentrations of chitosan nanoparticles (CSN) incorporated in universal composite resin and eighth-generation dentin bonding agent (DBA). Seventy extracted human maxillary first molar teeth were cleaned and mounted in acrylic mold up to 2 mm below cementoenamel junction and mesio-occlusal Class II cavities with standard measurements were prepared. CSN 2% and 0.25% powder were added to the DBA and composite resin. The samples then arbitrarily divided into three groups for restoration: Group 1: composite restoration without CSN (control group) (n = 10), Group 2: 2% CSN (n = 30), and Group 3: 0.25% CSN (n = 30). Groups 2 and 3 were further subdivided into three subgroups (n = 10 each) subgroup A. CSN incorporated in composite resin. B. CSN incorporated in DBA and C. CSN incorporated in composite and DBA. After restoration, push-out bond strength was evaluated in each sample using a universal testing machine, and data collected were statistically analyzed by one-way analysis of variance and Post hoc Tukey tests (P ≤ 0.05). Subgroup 3A (0.25% CSN + composite) has shown an increase in bond strength among all experimental groups with no significant difference between group 1 (control group). CSN 0.25% incorporated in composite or DBA exhibits no harmful effect on the bond strength of class II restorations. Hence, it can be used to improve the antibacterial action and longevity of composite resin.

Effect of MDP concentration and addition of iodonium salt on the dentin bond strength of experimental adhesives

Objective: The aim was to evaluate the bond strength of six experimental adhesives containing binary or ternaryphotoinitiator systems, associated with three different MDP concentrations (0-12wt%) after 12 months ofstorage in distilled water. Material and Methods: Experimental adhesives were prepared with: bis-GMA, UDMA,bis-EMA, TEGDMA, HEMA, BHT, and ethanol, containing binary (CQ/amine) or ternary (CQ/amine/DPIHFP(diphenyliodonium hexafluorophosphate) – 0.5wt%) photoinitiator systems. It was added to this composition0wt%, 6wt%, or 12wt% of MDP. The adhesive systems were applied following the etch-and-rinse protocol.Transparent cylindrical molds were placed on the hybridized dentin, filled with composite resin and light-cured.The specimens were stored in distilled water at 37oC for 24h or 12 months and submitted to a microshear bondstrength test (n=6). Data were analyzed by three-way ANOVA and Tukey’s test (a =5%). Results: For the binarysystem, after 12 months of storage, all bond strength values were similar. Regarding bond strength degradationover time, 6wt% and 12wt% MDP formulations showed more stable bond strength than 0wt% MDP. For the ternarysystem, all formulations (0wt%, 6wt% and 12wt%) showed stable bond strength over time. Conclusion: For thebinary photoinitiator system, the 6wt% and 12wt% MDP concentrations were able to keep bond strength stableover time, while for the ternary system, bond strength stability was achieved regardless the MDP concentration. KEYWORDSDental bonding; Dental photoinitiators; Dentin-bonding agents; MDP.

The Effect of Different Condition of Pulpal Pressure on Microtensile Bond Strength of Several Dentin Bonding Agents on Deep and Superficial Dentin.

The objective of this study was to examine the effect of different conditions of simulated hydrostatic pulpal pressure on the μTBS of HEMA-based and HEMA-free dentin bonding agents (DBAs). The influence of dentin location (deep and superficial) on μTBS was also evaluated. Flat coronal dentin surfaces of extracted human molars were prepared. Three groups of resin-bonded specimens were exposed to different pulpal pressures. Pulpal pressure was maintained for 20 min for each group. A flowable resin composite was used for coronal build-up. The bonded teeth were sectioned and, after 24 h of water storage, stressed to failure using the microtensile tester (μTBS). Failed samples were analyzed by SEM inspection. HEMA-based DBAs were much more sensitive to pulpal pressure conditions than non-HEMA-containing DBAs. Pulpal pressure had a greater influence in deep dentin. The HEMA-free DBA was insensitive to the presence or absence of pulpal pressure condition. SEM inspection confirmed a relationship between the presence of voids inside the HEMA-based DBAs layer and the lower μTBS results. HEMA-based DBAs are more sensitive to pulpal pressure conditions than HEMA-free DBAs. Interestingly, HEMA-free DBA showed a greater number of water droplets at resin–dentin interface in all tested conditions.

Dentin surface and hybrid layer morphological analysis after use of a copaiba oil- based dentin biomodifier

This study evaluated dentin surface and hybrid layer’s morphology, using copaíba (CO) emulsion as dentin biomodifier before traditional and self-etching adhesive, by environmental scanning electron microscopy (ESEM). Ninety-six third sound molars were divided into 16 groups, according to the dentin substrate, tested substances, and the adhesive system used. The conditioned dentin surface treated with clorexidina (CHX) 2% showed phosphate salts on two dentin substrates as well as the sound conditioned or not surface treated with calcium hydroxide solution (CHS), where the mineral precipitate deposition obstructs the tubules lumen. A significant difference (p &lt;0.0001) in dentin surface morphology was observed at the CHS group on conditioned and not conditioned sound dentin. The CO emulsion produced a regular and homogenous hybrid layer with many resin tags on both dentin surfaces, irrespective of the adhesive system used, with better performance than CHS and CHX 2% (p =0.0007) on caries-affected dentin at the self-etching group. CO emulsion showed no morphological changes on sound and caries-affected dentin and presented a regular hybrid layer, regardless of the adhesive system used.&#x0D; Keywords: Copaiba oleoresin; Emulsions; Dentin-bonding agents; Phytotherapy.

Nanoparticle incorporated dentin bonding agent to caries effected dentin treated by photodynamic therapy, laser or chlorhexidine

PurposeThis study aims to evaluate the microtensile bond strength (µTBS) and failure modes of graphene nanoplatelets doped with hydroxyapatite (GNP-HA) modified self-etch dentin bonding agent (DBA) to caries effected dentin (CAD) after various conventional and laser disinfection protocols. Materials and MethodsGraphene nanoplatelets and HA nanoparticles were doped and incorporated in DBA. Fifty carious human molar teeth were used for the experiment. CAD specimens were divided into five groups (n=10/group) into CAD undergoing no disinfection treatment (Group-CAD), 2% chlorhexidine disinfection (Group-CHX), 6% NaOCl disinfection (Group-NaOCl), methylene blue assisted PDT (Group-MB-PDT), and Er,Cr:YSGG laser application (Group-Er,Cr:YSGG). Following the respective disinfection techniques, the GNP-HA modified adhesive was applied to all treated CAD surface. Subsequently µTBS and failure modes were analyzed. ResultsRepresentative scanning electron microscope images (SEM images) of the synthesized GNP-HA indicated flakes of graphene with varying size lengthwise (>500 nm) with 1-2 nm width. The doped HA showed round and spherical morphology conjugated over the surface of the GNP measuring 40 -100 nm in diameter. CAD group that underwent no treatment represented the highest µTBS (29.43 MPa). Within the tested specimens, MB-PDT (22.37 MPa) and Er,Cr:YSGG (21.85 MPa) showed the highest µTBS values than CHX (15.69 MPa) and NaOCl (11.46 MPa). However, there was no significant difference between MB-PDT and Er,Cr:YSGG (p>0.05) and a significant difference existed between CHX and NaOCl (p<0.05). Equal distribution of cohesive and adhesive failures was noted for CAD, CHX and NaOCl treated specimens. A majority of adhesive failures existed in the MB-PDT groups. While admixed and adhesive failures were higher in Er,Cr:YSGG treated samples. ConclusionsThe outcome of this study suggests that CAD restored by GNP-HA modified self-etch adhesive showed highest bond strength after MB-PDT and Er,Cr:YSGG protocols with low amount of adhesive failure.

Effect of Three Different Cooling and Insulation Techniques on Pulp Chamber Temperature during Direct Temporization with Polymethyl methacrylate-based Resin

This in vitro study evaluates and compares the changes in pulp chamber temperature during direct fabrication of provisional restorations in maxillary central incisors after using three different cooling techniques. Total of 60 samples of maxillary central incisors along with their putty indices were divided into four groups (one control and three experimental) and were prepared using a surveyor cum milling machine. Teeth were sectioned 2 mm below cementoenamel junction and a K-type thermocouple wire was inserted in the tooth and secured at the pulpal roof using amalgam. Putty index filled with DPI tooth molding resin material [polymethyl methacrylate (PMMA)] was placed on the tooth and temperature changes per 5 seconds were recorded by temperature indicating device for the control, on-off, precooled putty, and dentin bonding agent (DBA) group. The highest mean obtained was of the control (11.04°C), followed by DBA group (9.53°C), precooled putty group (6.67°C), and on-off group (1.94°C). Precooled putty index group took maximum time to reach the baseline temperature (847.5 seconds). On-off technique is the most effective method to reduce the intrapulpal temperature during polymerization, as compared to the other techniques used in the study. Retardation in the polymerization process was seen in precooled putty group, which may make this technique clinically inadvisable. Thermal protection of pulp must always be considered during direct fabrication of provisional restoration when a PMMA-based resin is used. By using on-off technique, not only the thermal insult to the pulp can be effectively minimized but also the harmful effects of residual monomer (poor marginal fit and pulpal irritation) can be eliminated.

Immunoxpression of MMPs -9, -13 and TIMP-3 after Using Etch-and-rinse Adhesive

The aim of the present study was to determine the expression of MMP-9, MMP-13 and TIMP-3 after using the XP Bond ™ (Dentsply) dentin-bonding agent on 21 human teeth. Class I deep cavities were prepared and restored. After 01, 07, 14, 21, 30, 90 and 120 days, the teeth were extracted and processed for an immunohistochemical assessment (n=3). Immunohistochemical staining was performed using the monoclonal antibody anti-MMP-9, and polyclonal antibodies anti-MMP-13 and anti-TIMP-3. The immunoreactivity of metalloproteinases 9 and 13 was considered intense and moderate in the first storage intervals, before decreasing over time. In contrast, the immunoreactivity of TIMP-3 was considered absent in dentin and weak in pulp in the first time intervals, and completely absent in the subsequent intervals. MMP-9 expression in dentin and in pulp was prevalent in the dentinal tubules and odontoblastic layer, respectively. MMP-13 expression in dentin and in pulp was predominant in the pre-dentine region and odontoblastic layer, respectively. TIMP-3 expression was absent in dentin and predominantly located in the odontoblastic layer for pulp. In conclusion, the expression patterns of MMP-9, MMP-13 and TIMP-3 altered in the different time intervals studied. The increased expression of TIMP-3 in the first time intervals could suggest a synchronous response to the increased expression of MMPs in the same periods. The results confirmed the low performance of TIMP-3 in the physiological processes of the pulp-dentin complex for the conditions and materials tested herein.