BACKGROUNDThe wet-bonding technique is recommended for the one-bottle dentin adhesive systems, but the moisture concept varies widely among the instructions of manufacturers as well as among investigators. The aim of this study was to evaluate the effects of different dentin surface moisture on the microtensile bond strength(s) of an ethanol/water-based adhesive system and an acetone-based system to dentin.

METHODSForty intact human premolars extracted for orthodontic reasons were used. Superficial occlusal flat dentin surfaces of these premolars were exposed, finished with wet 600-grit silicon carbide paper. Under four wet and dry conditions (overwet, blot dry, one-second dry and desiccated), resin composite was bonded to dentin by using Single Bond (SB) or Prime & Bond NT (PB) according to the manufacturers' instructions. The teeth were longitudinally sectioned in the "x" and "y" directions to obtain bonded beams with a cross-sectional area of 0.81 mm(2) with a slow-speed diamond saw. The bonded specimens were tested in tension at a crosshead speed of 1 mm/min until failure of the bonds. Failure modes were observed with a scanning electron microscope. The mean bond strengths were analyzed by one-way ANOVA and Turkey's test.

RESULTSThe bond strength of the overwet/SB, blot dry/SB, one-second dry/SB and desiccated/SB groups was 10.87 MPa, 22.47 MPa, 24.91 MPa and 12.99 MPa, respectively. The bond strength of the overwet/PB, blot dry/PB, one-second dry/PB and desiccated/PB groups was 10.02 MPa, 20.67 MPa, 21.82 MPa and 10.09 MPa, respectively. For both SB and PB, the blot dry group and one-second dry group revealed significantly higher bond strengths than the overwet and desiccated groups (P < 0.05).

CONCLUSIONSIn order to achieve the highest bond strength to dentin, keeping the dentin surface in an appropriately moist condition is critical for the one-bottle dentin adhesive systems with ethanol/water or acetone solvent.

Adolescent ; Adult ; Dental Bonding ; Dentin-Bonding Agents ; pharmacology ; Humans ; Solvents ; Tensile Strength ; Water

Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.
Chlorhexidine ; pharmacology ; Collagen ; metabolism ; ultrastructure ; Dental Bonding ; Dentin ; enzymology ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Enzyme Inhibitors ; pharmacology ; Humans ; Hydrolysis ; Matrix Metalloproteinase Inhibitors ; Matrix Metalloproteinases ; metabolism ; Resin Cements ; chemistry

OBJECTIVETo examine, in vitro study, the ultrastructure of resin-infiltrated sclerotic dentine following the application of a two-step self-etching dentin adhesive.

METHODSNon-carious, natural cervical sclerotic lesions were bonded using Contax (DMG Hamburg, Germany), a self-etching dentin adhesive. Artificially prepared wedge-shaped lesions were also made in sound bicuspids and bonded using the same adhesive as controls. By SEM examination, the morphological change of the dentin surface treated by Contax Primer, and the hybrid layer and resin tag in the dentin-resin interface were studied.

RESULTSMost dentinal tubules were occluded by rod-like sclerotic casts in the sclerotic dentin surface. Both hybrid layer and resin tag were observed in sclerotic dentin. The hybrid layer was almost similar to that in the sound dentin, but the resin tags were shorter than those in controls.

CONCLUSIONSBonding to sclerotic dentin is different from sound dentin and may be compromised by occluded dentin tubules. Based on the present ultrastructural features of hybrid layer and resin tags, the Contax, a self-etching dentin adhesive with a low pH value primer, may have some bonding efficacy to sclerotic dentin.

Dentin ; drug effects ; ultrastructure ; Dentin-Bonding Agents ; pharmacology ; Humans ; Microscopy, Electron, Scanning ; Tooth Cervix ; drug effects ; ultrastructure

OBJECTIVETo investigate the potential effect of proanthocyanidins (PA), a natural cross-linker, on the stability of resin-dentin bonds against thermal cycling.

METHODSTen percent, 15% PA-based preconditioners, and 5% glutaraldehyde were prepared for the transient pretreatment of demineralized dentin before bonding. Specimens without pretreatment were used as negative controls (n = 4 teeth for each group). Microtensile bond strength, failure mode, micromorphologies of resin-dentin interface and the collagen degradation of bonded specimens after thermal cycling were evaluated.

RESULTSAfter thermal cycling, the microtensile bond strength values of resin-dentin bond in groups pretreated with 15% PA for 120 s and 60 s [(23.09 ± 3.19) and (21.88 ± 3.49) MPa] were significantly higher than that in control group [(15.47 ± 3.78) MPa] (P < 0.05). Mixed fractures were the most prevalent failure mode. Specimens with pretreatment presented compact hybrid layer, while some narrow gaps were found in hybrid layer of non-treated specimens. Collagen biodegradation rates in groups with pretreatment were significantly lower than that in control group (P < 0.05). Among them, specimens pretreated by 15% PA preconditioner for 120 s exhibited the lowest biodegradation rates [(0.316 ± 0.019) mg/g].

CONCLUSIONSThe application of natural cross-linker PA on demineralized dentin reduced the bond degradation against aging by thermal cycling, and can be helpful to create more durable bonds to dentin.

Collagen ; metabolism ; Dental Bonding ; Dental Stress Analysis ; Dentin ; Dentin-Bonding Agents ; Humans ; Proanthocyanidins ; pharmacology ; Resin Cements ; Temperature ; Tensile Strength ; drug effects

OBJECTIVETo observe the influence of chemomechanical caries removal on dentin adhesion by scanning electron microscope.

METHODSThe ultrastructure of dentin surfaces and adhesives-dentin bonding interfaces after caries removal by chemomechanical method or drilling were observed.

RESULTSLess smear layer in dentin surface, resin tags in the interface between dentin and Prime&Bond NT/compomer and numerous resin tags and more uniform and closer hybrid layer in the interface between dentin and Adper Prompt-L-Pop/composite were found in chemomechanical preparation than in drilling preparation.

CONCLUSIONSChemomechanical caries removal can benefit dentin adhesion.

Acid Etching, Dental ; Dental Bonding ; Dental Caries ; pathology ; therapy ; Dental High-Speed Equipment ; Dentin ; drug effects ; ultrastructure ; Dentin-Bonding Agents ; pharmacology ; Humans ; Microscopy, Electron, Scanning ; Surface Properties

OBJECTIVES: Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy. METHODS: Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed. RESULTS: Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all P<0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules increased after using ERY, but without significant difference (all P>0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, the scores of formation of resin tags under SEM gradually increased with the increase of concentration of NaOCl solution, while the score in the 5.25% NaOCl group decreased significantly compared with the score of the 2.5% NaOCl group (P<0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (all P>0.05). The scores of length of the tags under SEM in the 5.25% NaOCl group was significantly higher than the scores of DW, 0.5% NaOCl, and 1% NaOCl groups (all P<0.05), and it was also higher than the score of the 2.5% NaOCl group, but without significant difference (P>0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (P>0.05). The scores of formation of hybrid layer under SEM in the 2.5% NaOCl and 5.25% NaOCl groups significantly decreased compared with the score of the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). Microtensile bond strength was greater in the 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, but lower in the 5.25% NaOCl group than that in the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). The incidence of type "Adhesive" of failure modes in the 5.25% NaOCl group was significantly higher than that in other groups (all P<0.05), while the incidence of type "Adhesive" in the 5.25% NaOCl+10% ERY group was lower than that in the 5.25% NaOCl group (P<0.05). CONCLUSIONS The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.
Adolescent ; Adult ; Ascorbic Acid ; Dental Bonding ; Dentin ; Dentin-Bonding Agents/pharmacology* ; Diamond/pharmacology* ; Humans ; Materials Testing ; Microscopy, Electron, Scanning ; Resin Cements/pharmacology* ; Sodium Hypochlorite/pharmacology* ; Tensile Strength ; Water/pharmacology* ; Young Adult

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P < 0.05). The SBMP + MPC + DMAHDM group had protein adhesion that was only 1/20 of that of the SBMP control (P < 0.05). Incorporation of MPC and DMAHDM into SBMP provided a synergistic effect on biofilm reduction. The antibacterial effect and resistance to protein adsorption exhibited no decrease from 1 to 180 d (P > 0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.
Anti-Infective Agents ; chemistry ; pharmacology ; Biofilms ; drug effects ; Dental Bonding ; Dentin-Bonding Agents ; chemistry ; pharmacology ; Materials Testing ; Methacrylates ; chemistry ; pharmacology ; Phosphorylcholine ; analogs & derivatives ; chemistry ; pharmacology ; Resin Cements ; Shear Strength ; Surface Properties ; Water

Acid Etching, Dental ; adverse effects ; Chondroitin ABC Lyase ; chemistry ; Dental Bonding ; Dentin ; chemistry ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Humans ; Hydrolysis ; Matrix Metalloproteinase Inhibitors ; pharmacology ; Matrix Metalloproteinases ; metabolism ; Microscopy, Electron, Transmission ; Surface Properties

OBJECTIVEThis in vitro study was to evaluate the micro-tensile bond strength (microTBS) of three adhesives to sclerotic dentin in non-carious cervical lesions.

METHODSThe maxillary premolars extracted due to periodontitis and with non-carious cervical lesions were collected. The non-carious, natural cervical sclerotic lesions were bonded with a total-etching adhesive Scotchbond Multi-Purpose, a two-step self-etching adhesive Contax, and an all-in-one self-etching adhesive Adper Prompt L-Pop. Artificially prepared wedge-shaped lesions were also made in sound premolars and bonded with the same adhesives as the controls. MicroTBS of these three adhesives was measured.

RESULTSMicroTBS of Scotchbond and Contax to sclerotic dentin was significantly lower than to normal dentin. But microTBS of Adper Prompt L-Pop to normal dentin was significantly lower than to sclerotic dentin. MicroTBS to sclerotic dentin was Scotchbond 46.805 MPa, Adper Prompt L-Pop 39.045 MPa, and Contax 29.852 MPa.

CONCLUSIONSIn sclerotic dentin the microTBS was decreased because of the inferior micro-morphology of resin tags. Adhesives with low pH value might bond to sclerotic dentin effectively.

Bisphenol A-Glycidyl Methacrylate ; pharmacology ; Composite Resins ; pharmacology ; Dental Cements ; pharmacology ; Dentin ; drug effects ; physiology ; Dentin-Bonding Agents ; pharmacology ; Humans ; In Vitro Techniques ; Organophosphates ; pharmacology ; Resin Cements ; pharmacology ; Tensile Strength ; drug effects ; Tooth Abrasion ; therapy ; Tooth Cervix ; pathology

OBJECTIVETo investigate the effect of epigallocatechin-3-gallate (EGCG) on biomodification of demineralized dentine substrate, in its permeability, hydrophobicity, and inhibition ability to collagen enzymatic degradation.

METHODSThe dentine substrates were treated with simulated pulpal pressure created by mixtures of 0.02%, 0.1% EGCG/bovine serum albumin (BSA) in acidic environment (pH4.4) for 48 h. A fluid-transport model was used to measure the fluid permeability through demineralized dentine substrate. Positive replicas of dentine substrate were fabricated before and after being subjected to acidic environment for scanning electron microscope (SEM) examination. The blank group contained no EGCG and the positive group were treated with Gluma desensitizer. Static contact angle measurements on demineralized dentin and 0.1% EGCG primed dentin were performed by contact angle analyzer. The priming time were 60 s, 120 s, 0.5 h, 1 h. Dentine specimens bonded with Adper single bond 2 were subjected to 100 mg/L collagenase and observed under SEM. Resin-bonded specimens (with 0.02%, 0.1%, 0.5% EGCG priming, or without EGCG priming) were created for micro-tensile bond strength evaluation (MTBS). Resin-bonded specimens after thermol cycling were created for MTBS evaluation.

RESULTSThe fluid permeability in the blank control group increased ([151.3±22.3]%), the fluid permeability in 0.1% EGCG/BSA group decreased ([23.7±6.3]%). Compared to the blank control group, the contact angle of 120 s, 0.5 h, 1 h groups increased by 31.0%, 53.5%, 57.8% in deep dentin and 37.4%, 59.3%, 62.4% in shallow dentin. The SEM examination showed that 0.1% and 0.5% EGCG priming for 120 s significantly increased dentin collagen's resistance to collagenase. The immediate MTBS of 0.1% and 0.5% EGCG groups were (29.4±4.8) and (19.8± 4.9) MPa. After thermol cycling, the MTBS of 0.1% and 0.5% EGCG groups were (19.9±5.1) and (15.3± 6.3) MPa.

CONCLUSIONSUnder acidic environment (pH4.4), the 0.1% EGCG can reduce dentine permeability under acidic environment. The 0.1% EGCG can increase hydrophobicity of dentin substrate, and strengthen dentin substrate's resistance to collagenase hydrolysis, thus increased the resin-dentin bonding durability.

Acid Etching, Dental ; Catechin ; analogs & derivatives ; pharmacology ; Collagen ; chemistry ; drug effects ; Collagenases ; pharmacology ; Composite Resins ; Dental Bonding ; Dental Cements ; Dental Pulp ; Dentin ; chemistry ; drug effects ; Dentin Permeability ; drug effects ; Dentin-Bonding Agents ; Glutaral ; pharmacology ; Hydrogen-Ion Concentration ; Hydrolysis ; Methacrylates ; pharmacology ; Microscopy, Electron, Scanning ; Pressure ; Resin Cements ; Serum Albumin, Bovine ; pharmacology ; Tensile Strength ; Time Factors