Resin-dentin Bond Research Articles

Graphene oxide nano-filler based experimental dentine adhesive. A SEM / EDX, Micro-Raman and microtensile bond strength analysis.

The study aimed to assess graphene oxide (GO) adhesive and its dentin interaction using scanning electron microscopy (SEM), MicroRaman spectroscopy and Microtensile bond strength (μTBS). Experimental GOA and control adhesives (CA) were fabricated. Presence of GO within the experimental adhesive resin was assessed using SEM and Micro-Raman spectroscopy. Ninety specimens were prepared, sixty teeth were utilized for μTBS, twenty for SEM analysis of interface for CA and GOA and ten were assessed using microRaman spectroscopy. Each specimen was sectioned and exposed dentine was conditioned (35% phosphoric acid) for 10 s. The surface was coated twice with adhesive (15 s) and photopolymerized (20 s). Composite build-up on specimen was photo-polymerized. Among the bonded specimens, thirty specimen were assessed using Micro-Raman spectrometer, SEM and energy dispersive X-ray spectroscopy (EDX), whereas remaining specimens were divided in to three sub-groups (n = 10) based on the storage of 24 h, 8 weeks and 16 weeks. μTBS testing was performed at a crosshead speed of 0.5 mm/min using a microtensile tester. The means of μ-tbs were analyzed using ANOVA and post hoc Tukey multiple comparisons test. No significant difference in μTBS of CA and GOA was observed. Storage time presented a significant interaction on the μTBS (p < 0.01). The highest and lowest μTBS was evident in CA (30.47 (3.55)) at 24 h and CA (22.88 (3.61)) at 18 weeks. Micro-Raman analysis identified peaks of 1200 cm-1 to 1800 cm1, D and G bands of GO nanoparticles in the resin. Uniform distribution of graphene oxide nanoparticles was present at the adhesive and hybrid layer. GO showed interaction within adhesive and tooth dentin similar to CA, along with formation of hybrid layer. In ideal conditions (absence of nanoleakage), graphene oxide modified adhesive shows comparable bond strength and durability of resin dentine bond.

Development of an antibacterial and anti-metalloproteinase dental adhesive for long-lasting resin composite restorations.

Despite all the advances in adhesive dentistry, dental bonds are still fragile due to degradation events that start during application of adhesive agents and the inherent hydrolysis of resin-dentin bonds. Here, we combined two outstanding processing methods (electrospinning and cryomilling) to obtain bioactive (antimicrobial and anti-metalloproteinase) fiber-based fillers containing a potent matrix metalloproteinase (MMP) inhibitor (doxycycline, DOX). Poly(ε)caprolactone solutions containing different DOX amounts (0, 5, 25, and 50 wt%) were processed via electrospinning, resulting in non-toxic submicron fibers with antimicrobial activity against Streptococcus mutans and Lactobacillus. The fibers were embedded in a resin blend, light-cured, and cryomilled for the preparation of fiber-containing fillers, which were investigated with antibacterial and in situ gelatin zymography analyzes. The fillers containing 0, 25, and 50 wt% DOX-releasing fibers were added to aliquots of a two-step, etch-and-rinse dental adhesive system. Mechanical strength, hardness, degree of conversion (DC), water sorption and solubility, bond strength to dentin, and nanoleakage analyses were performed to characterize the physico-mechanical, biological, and bonding properties of the modified adhesives. Statistical analyses (ANOVA; Kruskal-Wallis) were used when appropriate to analyze the data (α = 0.05). DOX-releasing fibers were successfully obtained, showing proper morphological architecture, cytocompatibility, drug release ability, slow degradation profile, and antibacterial activity. Reduced metalloproteinases (MMP-2 and MMP-9) activity was observed only for the DOX-containing fillers, which have also demonstrated antibacterial properties against tested bacteria. Adhesive resins modified with DOX-containing fillers demonstrated greater DC and similar mechanical properties as compared to the fiber-free adhesive (unfilled control). Concerning bonding performance to dentin, the experimental adhesives showed similar immediate bond strengths to the control. After 12 months of water storage, the fiber-modified adhesives (except the group consisting of 50 wt% DOX-loaded fillers) demonstrated stable bonds to dentin. Nanoleakage was similar among all groups investigated. DOX-releasing fibers showed promising application in developing novel dentin adhesives with potential therapeutic properties and MMP inhibition ability; antibacterial activity against relevant oral pathogens, without jeopardizing the physico-mechanical characteristics; and bonding performance of the adhesive.

Application of natural crosslinkers on tooth surface: an in-vitro comparative evaluation of resin-dentin bond strength.

To investigate the effect of natural crosslinkers proanthocyanidin, genipin and glutaraldehyde on shear bond strength at the composite resin-dentin interface . The in-vitro study was conducted at the Postgraduate Medical Institute, Lahore, Pakistan, from June to September 2018. Exposed dentin surfaces of extracted teeth were conditioned and randomly divided into proanthocyanidin, genipin, glutaraldehyde and control groups according to the type of surface treatment. The dentin surfaces were treated with 6.5% of primers proanthocyanidin, genipin, glutaraldehyde in the relevant groups, while teeth in the control group did not receive any primer application. After thorough rinsing, surfaces of all teeth were restored with a bonding agent and a restorative composite. After 24h, shear bond strength was tested at the Pakistan Council of Scientific and Industrial Research laboratories in Lahore. Pattern of fractures and quality of interface were investigated microscopically at the Lahore campus of COMSATS University, Islamabad. Data was analysed using SPSS 22. Of the 80 teeth, there were 20(25%) in each of the 4 groups. Surface treatment in the three intervention groups significantly raised the shear bond strength at the composite resin-dentin interface compared to the control group (p<0.05). Chemical modification with collagen crosslinkers improved bond strength at the composite resin-dentin interface.

Improving Resin-dentin Bond Durability and a Novel Ultra-high-speed Videography

Improving Resin-dentin Bond Durability and a Novel Ultra-high-speed Videography

Enhancing the Resin-Dentin Bond with DMSO: A Narrative Review

Enhancing the Resin-Dentin Bond with DMSO: A Narrative Review

Influence of collagen cross-linkers addition in phosphoric acid on dentin biomodification and bonding of an etch-and-rinse adhesive

ObjectiveTo investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (μTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive. MethodsExperimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15s etching to detect collagen cross-linking. Extracted third molars were used for μTBS (n=7) and fracture mode analysis of Optibond S (Kerr), tested after 24h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey’s test (p<0.05). ResultsFTIR confirmed cross-linking for all agents. μTBS of CC was the highest (46.6±6.2MPa), but reduced significantly after aging (35.7±5.2MPa) (p<0.001). LIG (30.6±3.7MPa) and CARD (28.3±1.8MPa) attained similar μTBS which were stable after aging (p>0.05). Fracture mode was predominantly adhesive. At 24h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer. SignificanceAltogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.

Effect of polyvinylphosphonic acid on resin-dentin bonds and the cytotoxicity of mouse dental papilla cell-23

Statement of problemPolyvinylphosphonic acid (PVPA) could be used as a biomimetic remineralization analog and a matrix metalloproteinases (MMPs) inhibitor. However, studies are lacking regarding the performance of PVPA in dental bonding systems for maintaining the durability of the resin-dentin bond. PurposeThe purpose of this in vitro study was to investigate the effect of PVPA on the durability of resin-dentin bonds and the viability of mouse dental papilla cell-23 (MDPC-23). The mechanical properties of resin-dentin interfaces during long-term storage were analyzed, and the potential application of PVPA as a biomimetic remineralization analog in adhesive dentistry was evaluated. Material and methodsSeventy-five extracted noncarious human third molars were collected and randomly divided into 5 groups, and then the microtensile bond strength (μTBS) data and scanning electron microscope (SEM) images were used to evaluate the preservation condition of resin-dentin bonds after 1 day, 6 months, and 1 year of storage. The cytotoxicity of PVPA was detected by cell proliferation assay and cell apoptosis assay. ResultsCompared with the control and chlorhexidine (CHX) groups, the combined group (treated with both 200-μg/mL PVPA and biomimetic remineralization) had excellent bond durability. The exposed collagen fibril from the PVPA-treated groups (included 200-μg/mL and 500-μg/mL PVPA groups and a combined group) still showed integrity after 1 year of storage when compared with the control group. PVPA up to 500 μg/mL showed no cytotoxicity to MDPC-23 and did not inhibit cell growth. ConclusionsThis study offered evidence that PVPA did not result in cytotoxicity at low concentrations as an MMP inhibitor and a biomimetic remineralization analog. In addition, the application of PVPA improved bond strength and preserved collagen integrity after 1 year of in vitro storage.

Bond stability of conventional adhesive system with MMP inhibitors to superficial and deep dentin

PurposeTo evaluate the microshear bond strength (μSBS) to deep (DD) or superficial (SD) dentin (μSBS) overtime, nanoleakage (AG%), degree of conversion (DC%), water sorption (WSp), and solubility (WSl) of an adhesive system [Adper Single Bond 2(ASB)] containing matrix metalloproteinases (MMP) inhibitors [GM1489 (ASB-GM), Batimastat (ASB-BAT), or Chlorhexidine diacetate (ASB-CHX)]. ASB without inhibitor was used as control (CONTROL). Materials and methodsWSp and WSL were calculated based on ISO4049. DC% was analyzed using FT-IR spectroscopy. Dentin discs were used for μSBS evaluation. For AG%, resin-dentin beams were analyzed under scanning electronic microscopy. Data were analyzed using three-way ANOVA (AG% and μSBS) or ANOVA (DC%, WSp, WSl) and Tukey’s HSD test. ResultsASB-CHX presented the lowest DC%, lowest WSp, and highest WSl. ASB-GM reached the highest immediate μSBS in SD, only different from ASB-CHX. In DD, ASB-BAT and ASB-GM had the highest μSBS, statistically different from ASB-CHX. After twelve months, ASB-GM and ASB-BAT presented higher μSBS in SD when compared to CONTROL and ASB-CHX. In DD, ASB-GM reached the highest value, which was statistically different from CONTROL and ASB-CHX. CONTROL at both dentin depths and ASB-CHX at DD did not maintain bond stability. In SD after 12 months, ASB-BAT and ASB-GM decreased AG%. In DD, only ASB-GM reduced AG%. ConclusionThe ASB containing Batimastat and GM1489 maintained resin-dentin bond stability after 12 months for both dentin depths, without jeopardizing WSp, WSl, or DC% of the adhesive system. The ASB-GM presented greater μSBS after 12 months when compared with ASB. Clinical significanceBatimastat and GM1489 could be suitable for inclusion as an MMP-inhibitor into Single Bond to improve the bond stability to superficial and deep dentin, without jeopardize the physic-mechanical proprieties.

Zinc oxide and copper nanoparticles addition in universal adhesive systems improve interface stability on caries-affected dentin

This study evaluated the MMP inhibition of the zinc oxide and copper nanoparticles (ZnO/CuNp), and the effects of their addition into adhesives on antimicrobial activity (AMA), ultimate tensile strength (UTS), in vitro degree of conversion (in vitro-DC), as well as, resin–dentin bond strength (μTBS), nanoleakage (NL) and in situ-DC on caries-affected dentin. Anti-MMP activity was evaluated for several MMPs. ZnO/CuNp (0% [control]; 5/0.1 and 5/0.2 wt%) were added into Prime&Bond Active (PBA) and Ambar Universal (AMB). The AMA was evaluated against Streptococcus mutans. UTS were tested after 24 h and 28d. After induced caries, adhesives and composite were applied to flat dentin surfaces, and specimens were sectioned to obtain resin–dentin sticks. μTBS, NL, in vitro-DC and in situ-DC were evaluated after 24 h. ANOVA and Tukey's test were applied (α = 0.05). ZnO/CuNp demonstrated anti-MMP activity (p < 0.05). The addition of ZnO/CuNp increased AMA and UTS (AMB; p < 0.05). UTS for PBA, in vitro-DC, in situ-DC and μTBS for both adhesives were maintained with ZnO/CuNp (p > 0.05). However, lower NL was observed for ZnO/CuNp groups (p < 0.05). The addition of ZnO/CuNp in adhesives may be an alternative to provide antimicrobial, anti-MMP activities and improves the integrity of the hybrid layer on caries-affected dentin.

The Effect of poly Amido Amine Denderimer Pretreatment Alone or with Nano hydroxyapatite Containing Adhesive on the Integrity of Resin Dentin Bond after PH Cycling.

Purpose: The purpose of the current study was to evaluate the effect of poly amidoamine dendrimer pretreatment alone and with Nanohydroxy apatite containing adhesive on the integrity of resin dentin bond as affected by PH Cycling . Materials and Methods: A total of eighty dentin samples were divided into four main (A) groups according to the material used where in (A1) group: (PAMAM –NH2) alone, (A2) group: HA containing adhesive alone,(A3) group :Combination of (PAMAM-NH2 +HA adhesive),(A4) group: The control adhesive alone .And each of (A) groups were further subdivided into two (B) groups according to PH Cycling where (B1) exposed to PH Cycling while (B2) not exposed. After (21 days) the shear bond strength of the specimens was measured and the samples were examined by(ESM).Results: For both (B1) and (B2),the results revealed that the highest mean value was recorded in (A3B1) and (A3B2) group while the lowest mean value was recorded in (A4B1)and (A4B2). Conclusion: All the treatment materials used were effective in improving the bond strength and the PH Condition has a significant role in the efficacy of different materials in increasing the bond strength.

Effect of chitosan on resin-dentin interface durability: A 2 year in-vitro study

Aim: The aim of the current study was to evaluate immediate and long-term bonding effectiveness of chitosan-treated dentin, bonded using 2-step etch-and-rinse dental adhesive, after 2 years of ageing.Materials & Methods: Microtensile bond strength test and nanoleakage examination of resin-dentin interfaces, created by Adper Single Bond 2 with or without chitosan pre-treatment, were performed after 24 h, 12 mos and 24 mos of water storage. Stiffness of demineralized dentin sticks treated with chitosan for 1 or 10 min was evaluated. Matrix metalloproteinases (MMPs) activity was also assessed by measuring the amount of hydroxyproline release, indicating collagen degradation by MMPs, after chitosan treatment for 1 or 10 min. Data were collected, tabulated and statistically analysed.Results: Chitosan treatment of acid-etched dentin, before adhesive application, resulted in microtensile bond strength values which are significantly higher (40.7± 1.7 MPa and 37.2±1.9 MPa respectively) and nanoleakage values (56.5±3.8% and 62±3.6 % respectively) that are significantly lower than the untreated control group at 12 mos and 24 mos storage periods (P ≤ 0.05). The stiffness of demineralized dentin increased significantly after 1 min chitosan application (12.6±1.8 MPa) and further increased after 10 min chitosan application (22.4± 2.2 MPa). Hydroxyproline released decreased significantly (P-value <0.001) when completely demineralized dentin was treated with chitosan for 1 min (1.1 µg/mg dentin) with further significant decrease when chitosan was used for 10 min (0.8 µg/mg dentin). Conclusion: Chitosan treatment of acid-etched dentin, before adhesive application, was effective in improving durability of resin-dentin bonded interfaces. Clinical Significance: Despite of the great advances that have occurred in the field of adhesive dentistry, still, biodegradation of resin-dentin bonds over time continues to jeopardize the durability and success of resin composite restorations.

Effect of Polymeric Microparticles Loaded With Catechin on the Physicochemical Properties of an Adhesive System.

The objective of this study was to synthesize and characterize epigallocatechin-3-gallate (EGCG)-loaded/poly(D-L lactide-co-glycolide) acid (PLGA) microparticles, evaluate their effects on degree of conversion and release assay of adhesives, and subsequently to examine the resin-dentin bond strength of two EGCG formulations (free EGCG or loaded into PLGA microparticles) applied as a pretreatment or incorporated into an adhesive system. The formulations were prepared according to a PLGA:EGCG ratio of 16:1 using the spray-drying technique. The size and polydispersity index were determined by light scattering in aqueous dispersion. The degree of conversion (%DC) and release assay were assessed by Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer, respectively. Subsequently, 45 third molars were divided into five groups (n=9) according to the different EGCG application modes and prepared for bond strength testing in a universal testing machine. Results demonstrated no statistically significant difference among the DC means after the PLGA microparticles were loaded with EGCG. For the release assay, the 1.0% PLGA/EGCG group presented better results after being elected for use in the bond strength test. The resin-dentin bond strengths of the experimental groups after 12 months of water storage were significantly higher than in the control group. EGCG could improve the durability of the resin-dentin bond over time and promote a new era for adhesive dentistry with the concept of controlled release.

Effect of a novel cold atmospheric plasma jet treatment with different temperatures on resin-dentin bonding

To investigate the effect of different treatment temperatures of a novel cold atmospheric plasma jet treatment on the resin-dentin bonding. (1) Fifty-two freshly extracted, non-carious and intact third molars were collected. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. One dentin disc [(900 ±100) μm] was prepared for each tooth. The fifty-two dentin discs were randomly divided into control group and experimental groups, of which four were in control group, and forty-eight were divided into four experimental groups according to the different treatment temperatures (4 °C, 10 °C, 20 °C and 30 °C) of the novel radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet, twelve in each group. Each experimental group was divided into three subgroups according to different treatment time (10 s, 20 s and 30 s), with four in each subgroup. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. The morphology of demineralized dentin surfaces was analyzed using field emission scanning electron microscopy. (2) Twenty unerupted, non-carious and intact third molars were randomly divided into five groups, four in each group: control group, untreated; 4 °C, 10 °C, 20 °C and 30 °C experimental groups, each group was treated with the RF-APGD plasma jet for 20 s. The micro-tensile resin dentin bond strength was tested after 20 s RF-APGD plasma jet treatment with different temperatures, using a universal mechanical machine. (1) The field emission scanning electron microscopy results indicated that when compared with the control group, a 10 s RF-APGD plasma jet treatment with 30 °C and 20 °C collapsed the collagen scaffold. Collagen fibrils maintained an uncollapsed three-dimensional structure after the 4 °C RF-APGD plasma jet treatment for even 30 s treatment. (2) The microtensile resin dentin bond strength results of the 4 °C RF-APGD plasma jet treatment group (57.8±0.7) MPa were significantly higher than that of the control group [(47.4±0.5) MPa] and 10 s, 20 s and 30 s RF-APGD plasma treatment group [(51.9±0.7) MPa,(29.7±1.0) MPa and (22.2±1.5) MPa] with statistically significant difference (P<0.05). Compared with the control group, the micro-tensile bond strength increased about 21.9% and 9.5% after 4 °C and 10 °C RF-APGD plasma jet treatment, respectively. Compared with other treatment temperatures, this novel RF-APGD plasma jet treatment with the temperature of 4 °C can preserve the three-dimensional morphology of demineralized dentin better, and can improve the resin-dentin bonding.

Biological, mechanical and adhesive properties of universal adhesives containing zinc and copper nanoparticles

ObjectivesTo evaluate the effect of addition of zinc oxide and copper nanoparticles (ZnO/CuNp) into universal adhesives, on antimicrobial activity (AMA), cytotoxicity (CTX), water sorption (WS) and solubility (SO), microhardness (MH) and in vitro degree of conversion (DC), as well as resin-dentin microtensile bond strength (μTBS), nanoleakage (NL) and in situ DC. MethodsZnO/CuNp (0% [control]; 5/0.1 and 5/0.2 wt%) were added in Prime&Bond Active (PBA) and Ambar Universal (AMB). The AMA was evaluated against Streptococcus mutans. For CTX, Saos-2 cell-line was used. For WS and SO, specimens were tested for 28d. For MH, specimens were tested after 24 h and 28d and for in vitro DC, specimens were evaluated after 24 h. After, the adhesives were applied to flat dentine surfaces, composite resin build-ups, specimens were sectioned to obtain resin–dentine sticks. It was evaluated in μTBS, NL and in situ DC after 24 h of water storage. ANOVA and Tukey’s test were applied (α = 0.05). ResultsThe addition of 5/0.2 ZnO/CuNp increase AMA and WS, but decrease the SO when compared to control (p < 0.05). The CTX and μTBS were maintaining with adhesive-containing ZnO/CuNp (p > 0.05). MH, in vitro DC and in situ DC was significant increase (AMB) or maintaining (PBA) with ZnO/CuNp addition. However, significantly lower NL was observed for ZnO/CuNp groups (p < 0.05). ConclusionsThe addition of ZnO/CuNp in the tested concentrations in universal adhesive systems may be an alternative to provide antimicrobial activity and improves the integrity of the hybrid layer, without jeopardizing biological, adhesives and mechanical properties. SignificanceThis is the first study that demonstrates that the addition of zinc oxide and copper nanoparticles in concentrations up to 5/0.2 wt% in two universal adhesive systems is a feasible approach and may be an alternative to adhesive interfaces with antimicrobial properties and less defects in the resin-dentin interface.

Effects of Baicalein on the Expression of Collagenolytic Enzymes in Human Dental Pulp Cells and Durability of Resin-Dentin Bonding.

In order to provide an experimental basis for the use of baicalein (BAI) as an enzyme inhibitor to improve resin-dentin bonding durability, this study explored the effect of BAI on the expression of matrix metalloproteinases (MMPs) and cathepsins in human dental pulp cells (HDPCs). The effects of various concentrations of BAI on the viability and cell cycle arrest of HDPCs were investigated in vitro. qPCR and Western blot analysis were performed to determine the effects of BAI on the expression of MMP-2, MMP-9, cathepsin-B, and cathepsin-K in HDPCs. Thermocycling (aging) was performed to determine the effect of BAI on the microtensile bond strength of aged resin-dentin bonding. Our results showed that BAI at concentrations below 25 μmol/l did not affect cell viability in HDPCs. Moreover, low concentrations of BAI effectively inhibited the expression of MMP-2, MMP-9, cathepsin-B, and cathepsin-K in HDPCs and improved the strength of aged resin-dentin bonding. BAI is a promising preconditioner for improving the durability of resin-dentin bonding by protecting against collagen degradation via the inhibition of MMPs and cathepsins.

Influence of silver nanoparticles on resin-dentin bond strength durability in a self-etch and an etch-and-rinse adhesive system

ObjectivesThis study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (µSBS) durability of different adhesives to dentin.Materials and MethodsOcclusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent µSBS testing after 24 hours and the other half was tested after 6 months of water storage.ResultsSNP application was associated with a higher µSBS than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower µSBS was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The µSBS values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05).ConclusionsSNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.

Synthesis and characterization of new hydrolytic-resistant dental resin adhesive monomer HMTAF

ABSTRACTHydrolytic and enzymatic degradation of resin adhesives over time has been mainly attributed to secondary caries formation of methacrylate-based tooth-colored resin-based composite restorations. Ability of resin adhesive monomers to infiltrate into demineralized dentin forming stiff polymer matrix and potentially bonding to tooth structure is also a crucial property. The only commercially available antibacterial monomer, 12-methacryloyloxydodecyl pyridinium bromide (MDPB), is a quaternary ammonium methacrylate. This methacrylate monomer undergoes hydrolytic degradation, and could not bond to tooth structure. In this study, a new hydrolytic resistant monomer HMTAF was synthesized. It is methacrylamide-based monomer that, unlike methacrylate, is highly resistant to hydrolysis. Its molecular structure has particular functional groups; quaternary ammonium fluoride salt with potential antibacterial fluoride-releasing activity, hydroxyl and amide group with hydrogen bonding potential to dentin collagen. Hydroxyl group also increases monomer hydrophilicity for better penetration into water-saturated dentin and sufficient resin-dentin bond. The synthesized HMTAF and its polymer showed no hydrolytic degradation in acidic environment, while MDPB and its polymer were partially decomposed under this challenge. The conversion of monomer HMTAF to polymer was illustrated by FT-IR. The results indicated that HMTAF is highly resistant to hydrolysis, polymerizable and non-cytotoxic to Vero cell lines. It is a potential monomer to be incorporated into resin adhesives for improving hydrolytic and enzymatic resistance.

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.

Effect of Er:YAG laser irradiation and chitosan biomodification on the stability of resin/demineralized bovine dentin bond

ObjectiveThe purpose of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan on the microtensile bond strength (µTBS), adhesive interface, dry mass loss and hydroxyproline release (HYP). MethodsArtificial lesions were created in 104 bovine dentin blocks. Blocks were divided according to caries removal method: bur or Er:YAG laser. Seventy-six blocks were acid etched and subdivided according to dentin biomodification: no chitosan and 2.5% chitosan. Composite resin restorations were performed. Blocks were sectioned into beams and stored in water. After 24 h, 6 and 12 months, beams were submitted to μTBS test (n = 10) and analysis of adhesive interface by SEM (n = 3). The other 28 blocks were sectioned into beams and initial dry mass (DM) was determined (n = 7). Beams were stored and after 7 days, DM was redetermined. HYP release (n = 7) was evaluated by ELISA. Data were analyzed by ANOVA and Bonferroni's tests (α = 0.05). ResultsAfter 24 h, the highest µTBS was found for bur (p < 0.001). After 6 months, methods were similar (p = 0.432). After 12 months, laser-irradiated dentin showed the highest µTBS values (p = 0.025). Chitosan promoted higher µTBS values after 6 (p = 0.011) and 12 months (p < 0.001) preserving adhesive interface. Dry mass loss and HYP release were not influenced (p > 0.05) by caries removal method or by dentin biomodification. ConclusionThe bond strength to demineralized dentin reduced over 50% in all groups after water storage. From 6 months of water storage, Er:YAG laser irradiation and biomodification with chitosan maintained the stability of the resin-dentin bonds, but did not influence dry mass loss and HYP release.

Effect of smear layer and surface roughness on resin-dentin bond strength of self-etching adhesives.

The purpose of this study was to evaluate the effect of surface roughness and smear layer on the micro-shear bond strength (µSBS) of two self-etching adhesives, Clearfil SE Bond (SE) and Clearfil Tri-S Bond (S3). Flat dentin surfaces were prepared with SiC papers (600-, 180- and 120-grit) and diamond burs (extra fine, medium and coarse). They were further divided into smear-covered and smear-free surfaces and bonded with respective adhesives. µSBS test was performed after water storage at 37ºC for 24 h. Smear layer thickness measurement was evaluated by scanning electron microscope (SEM). Surface roughness was examined by contact stylus profilometer. Smear layer thickness and surface roughness were significantly different among all groups (p<0.05). No difference in µSBS was observed among surface prepared by SiC whereas bur-cut smear layer had negative effect on µSBS, especially for S3. Surface roughness from different surface preparations had no influence on µSBS (p<0.05).