Differential effect of in vitro degradation on resin-dentin bonds produced by self-etch versus total-etch adhesives

OBJECTIVE: To evaluate the effect of an in vitro challenge (NaOCl immersion) on microtensile bond strength (MTBS) of five adhesive systems to dentin. METHODS: Flat dentin surfaces from 40 molars were bonded with three total-etch adhesives (Single Bond, Prime&Bond NT and the experimental Prime&Bond XP), and two self-etching agents (Clearfil SE Bond and Etch&Prime 3.0). Composite build-ups were constructed with Tetric Ceram. Teeth were then sectioned into beams of 1.0 mm2 cross-sectional area. Half of the beams were immersed in 10% NaOCl aqueous solution for 5 h. Each beam was tested in tension in an Instron machine at 0.5 mm/min. Data were analyzed by 2-way ANOVA and multiple comparisons tests (p < 0.05). RESULTS: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime resulted in the lowest MTBS. After NaOCl immersion, MTBS decreased in all groups. The highest MTBS values were obtained for Clearfil SE Bond and Prime&Bond XP. Scaning electron microscopy observation of debonded sticks evidenced dissolution and microstructural alterations of intertubular dentin, except when Clearfil SE Bond was used. CONCLUSIONS: Resin-dentin bonds are prone to chemical degradation. The extent of the resin degradation is adhesive system specific. Chemical degradation of the nonresin infiltrated collagen fibers does also exist in total-etch adhesives. Both processes may reduce long-term resin-dentin bond strength.     

Characterisation of resin-dentine interfaces by compressive cyclic loading

The aims of this in vitro study were to evaluate the ultra-morphological changes in resin-dentine interfaces after different amounts of thermomechanical load (TML), and to determine the corresponding microtensile bond strengths (microTBS). Enamel/dentine discs with a thickness of 2 mm were cut from 24 human third molars and bonded with four adhesives involving different adhesion approaches: Syntac (Ivoclar Vivadent; used as multi-step etch-and-rinse adhesive), Clearfil SE Bond (Kuraray; two-step self-etch adhesive), Xeno III (Dentsply DeTrey; mixed all-in-one self-etch primer adhesive system), and iBond (Heraeus Kulzer; non-mixed all-in-one self-etch adhesive). The resin-dentine discs were cut into beams (width 2 mm; 2 mm dentine, 2 mm resin composite) and subsequently subjected to cyclic TML using ascending amounts of mechanical/thermal cycles (20 N at 0.5 Hz of mechanical load and 5-55 degrees C of thermal cycles: for 0/0, 100/3, 1,000/25, 10,000/250, 100,000/2,500 cycles). Loaded specimens were either cut perpendicularly in order to measure microTBS (n=20; crosshead speed: 1 mm/min) or were immersed in an aqueous tracer solution consisting of 50 wt% ammoniacal silver nitrate and processed for ultra-morphological nanoleakage examination using transmission electron microscopy (TEM). microTBS were significantly decreased by increasing amounts of TML for all adhesives (p<0.05). Bond strengths after 0 vs. 100,000 thermomechanical cycles were: Syntac: 41.3/30.1 MPa; Clearfil SE Bond 44.8/32.5 MPa; Xeno III 27.5/13.7 MPa; iBond 27.0/6.2 MPa. Relatively early, a certain amount of nanoleakage was observed in all groups by TEM, which was more pronounced for Xeno III and iBond. The incidence of nanoleakage remained stable or was even reduced with increasing load cycles for all adhesives except iBond, where exact failure origins were detected within the adhesive and at the top of the hybrid layer.     

A challenge to the conventional wisdom that simultaneous etching and resin infiltration always occurs in self-etch adhesives

This study provided morphological evidence that discrepancies between the depth of demineralisation and the depth of resin infiltration can occur in some mild self-etch adhesives. Sound dentine specimens derived from extracted human third molars were bonded with 5 one-step and 5 two-step self-etch adhesives. One millimeter thick slabs containing the resin-dentine interfaces were immersed in 50 wt% aqueous ammoniacal silver nitrate and processed for TEM examination. A zone of partially etched but uninfiltrated dentine was identified beneath the hybrid layers in the milder versions of both one-step and two-step self-etch adhesives. This zone was characterised by the occurrence of silver deposits along the interfibrillar spaces of mineralised collagen fibrils. The silver infiltrated interfibrillar spaces were clearly identified from the one-step self-etch adhesives Xeno III, iBond, Brush&Bond and the experimental adhesive, and were thinner and only occasionally observed in the two-step self-etch adhesives Clearfil SE Bond and Clearfil Protect Bond. The more aggressive one-step and two-step adhesives that exhibit more abrupt transitions from completely demineralised to mineralised dentin were devoid of these silver-infiltrated interfibrillar spaces beneath the hybrid layers. Incomplete resin infiltration observed in some self-etch adhesives may be caused by the reduced etching potential of the acidic monomers toward the base of hybrid layers, or the presence of acidic but non-polymerisable hydrolytic adhesive components, creating potential sites for the degradation of the bonded created by these self-etch adhesives.     

Effects of two multi-step self-etch primer/adhesives on apoptosis in human gingival fibroblasts in vitro

Various in vitro studies have shown induction of apoptosis by monomers incorporated to dental restorative materials and adhesive resins, while information regarding the effect of monomer combinations as commercially available products on apoptosis is limited. The aim of this study was to investigate the effects of two multi-step self-etch primer/adhesive systems on apoptosis of cultured primary human gingival fibroblasts. Cells were treated up to 48 h with Clearfil SE Bond (Kuraray, Japan) and FL Bond (Shofu, Japan) at 1:1000 v:v ratio to determine cell proliferation, using 0.02 mM staurosporine as positive control. Apoptosis was assessed using propidium iodide/acridine orange (PI/AO) staining, compared to nontreated controls. When compared to FL Bond, exposure of gingival fibroblasts to Clearfil SE Primer and Clearfil SE Bond resulted in a higher degree of cell proliferation. PI/AO staining revealed typical morphological features of apoptosis in FL Bond and Staurosporine groups, while some cells cultured in the presence of primer and adhesive components of Clearfil SE Bond showed nuclear fragmentation, indicative of early apoptosis. Our results indicate that apoptotic potential of the multi-step self-etch adhesives were material-dependent within the 48 h test period.     

Influence of organic acids present in the oral biofilm on the microtensile bond strength of adhesive systems to human dentin

This study evaluated the influence of organic acids present in the oral biofilm on the microtensile bond strength (μTBS) of adhesive systems to human dentin. Sixty occlusal dentin surfaces were wet ground with 600 grit SiC abrasive paper and divided into four groups according to the adhesive systems: Scotchbond Multipurpose (SMP), Adper Single Bond 2, Adper Scotchbond SE (ASE), and Clearfill SE Bond (CSE). After the adhesive systems were applied, a block of resin composite was built up on the dentin surfaces. After 24 h storage in distilled water at 37°C, the teeth were perpendicularly cut to obtain beams (1 mm(2)). For each adhesive system, the beams were divided into three groups according to storage media: artificial saliva (AS); propionic acid (PA), and lactic acid (LA). After 7 days storage at 37°C, the beams were submitted to μTBS testing. The μTBS ranged from 36.0 ± 1.6 (ASE-PA) to 52.5 ± 1.2 (CSE-AS). For all adhesive systems, the μTBS values after storage in PA were lower than those in AS. Except for the SMP, the values of μTBS after storage in LA were lower than those in AS. The adhesive ASE presented the lowest values of μTBs in the three media. The acids present in the oral biofilm may affect the bond strength of adhesive systems to human dentin.     

Characterization of photopolymerization of dentin adhesives as a function of light source and irradiance

Manufacturers have attempted to address the limitations associated with dentin bonding by eliminating as many steps as possible in the bonding protocol. Theoretically, this approach increases the efficiency of the procedure and reduces technique sensitivity. These trends are reflected in the introduction of all-in one, single-step adhesive systems; the increased concentration of acidic resin monomers in these systems allows for simultaneous etching and priming of the prepared dentin surface. Ideally, the degree of monomer conversion would be high enough that the acidic reaction would be self-limiting. The purpose of this study was to investigate the effect of light irradiance and source on the photopolymerization of three commercial dental adhesives by monitoring the double bond conversion as a function of time during and after irradiation. The photopolymerization curing efficiency of the commercial adhesives investigated in this study varied as a function of light source and distance. The use of LED performed better than the halogen light in terms of polymerization rate and degree of conversion for the commercial single-step, sixth generation adhesive, Adper Prompt. In contrast, polymerization of commercial single-bottle, fifth generation adhesive, Single Bond and One-Up Bond F, was mainly a function of exposure time, irrespective of the two light units or intensities.     

Induction of cyclooxygenase-2 mRNA and protein expression by dentin bonding agents in human gingival fibroblasts

An ideal dentin bonding agent should be nonirritating to surrounding tissues. Unfortunately, all histological investigations have demonstrated that dentin bonding agents can induce mild to severe inflammatory alterations. However, there is little information on the precise mechanisms about dentin bonding agents-induced inflammatory reaction. Cyclooxygenase-2 (COX-2) is an inducible enzyme believed to be responsible for prostaglandin synthesis at the site of inflammation. The aim of the present study was to investigate the effects of three dentin bonding agents, Clearfil SE Bond, Prime & Bond NT, and Single Bond on the expression of COX-2 mRNA gene and protein in cultured human gingival fibroblasts. The exposure of quiescent human gingival fibroblasts to dentin bonding agents resulted in the induction of COX-2 mRNA expression. The investigations of the time-dependent on COX-2 mRNA expression in dentin bonding agent-treated human gingival fibroblasts revealed different patterns. The influence of COX-2 mRNA depended on the tested materials. In addition, all dentin bonding agents also induced COX-2 protein expression in human gingival fibroblasts. Taken together, the activation of COX-2 expression may be one of the potential mechanisms of dentin bonding agent-induced gingival inflammation.     

Cytotoxicity evaluation of an antibacterial dentin adhesive system on established cell lines

Clearfil Protect Bond is a new dental bonding agent recently introduced into clinical practice. It contains an antibacterial monomer that contributes to its antibacterial profile. The aim of the present study was to evaluate cytotoxic effect of Clearfil Protect Bond against three established fibroblastic cell lines, in comparison with four commonly used adhesive materials (Adper Scotchbond 1, Excite, Tyrian SPE, and One Step plus). The experiments were performed using RPC-C2A, BHK21/C13, and MRC5 cell lines. Test specimens, either cured or uncured, were placed in a culture medium and the extraction media were used as experimental material. The effect of the bonding materials was assessed by a modified sulforhodamine-B assay after 24 and 48 h of exposure. All tested agents exhibited an antiproliferative effect on cells, the effect on RPC-C2A being the most marked. Extraction media from the uncured materials were without exception highly cytotoxic. In the experiments performed using extraction medium from cured material, Clearfil Protect Bond appeared to be the least toxic material, followed by Tyrian SPE and One Step plus. Adper Scotchbond 1 and Excite exhibited the strongest cytotoxic effect. The cell survival percentage ranged between 66 and 97% for Clearfil Protect bond, 15 and 82% for Tyrian SPE, 28 and 58% for One Step plus, 2 and 28% for Excite, and 1 and 6% for Adper Scotchbond 1. Taking into consideration the limitations of an in vitro study, our results indicate that the new antibacterial dental adhesive system is suitable for clinical application.     

Effects of sodium hypochlorite gel and sodium hypochlorite solution on dentin bond strength

The aim of this study was to determine the effect of 10% NaOCl gel and 10% NaOCl solution on dentin bond strengths of four adhesive systems. One hundred eighty bovine incisors were ground to achieve a flat polished surface, then divided into 12 groups: Gluma One Bond [G1-control; G2-NaOCl solution; G3-NaOCl gel]; Prime & Bond 2.1 [G4-control; G5-NaOCl solution; G6-NaOCl gel]; Single Bond [G7-control; G8-NaOCl solution; G9-NaOCl gel]; Prime & Bond NT [G10-control; G11-NaOCl solution; G12-NaOCl gel]. Dentin was etched, rinsed, and blot dried. For the experimental groups, after acid etching, 10% NaOCl solution or 10% NaOCl gel was applied for 60 s, rinsed, and blot dried. Composite resin was inserted and light cured. Shear bond strengths were tested with a crosshead speed of 0.5 mm/min. The mean values MPa (SD) were analyzed with two-way ANOVA and Tukey's tests (alpha < 0.01). Ten percent NaOCl solution significantly increased Gluma One Bond strength. No effect was observed for the other adhesives. The 10% NaOCl gel did not affect bond strengths. Ten percent NaOCl gel was less effective on collagen removal as compared to 10% NaOCl solution. The influence of collagen removal on bond strength is dependent on adhesive system, where both the solvent and the monomer can influence the results.     

第7代黏接剂与正常和龋损牙本质黏接强度的比较

背景：对于第1~6代牙本质黏接剂的黏接强度,国内外学者做了大量的研究并取得了满意的成果,但尚未见对第7代黏接剂Adper EasyTM one黏接性能的相关报道。 目的：比较3M第7代自酸蚀黏接剂对正常和龋损牙本质黏接强度的差异,并与传统全酸蚀黏接剂进行对比。 方法：取健康磨牙和牙合 面慢性龋磨牙各12颗,分为A、B(健康磨牙),C、D(牙合 面慢性龋磨牙)4组,其中A、C组用Adper EasyTM one黏接剂,B、D组用Single bond 2黏接剂。测试4组试件的微拉伸强度,观察断裂界面形态。 结果与结论：A、B组的黏接强度分别为(21.84±3.98) ,(27.10±4.85) MPa,C、D组的黏接强度分别为(16.44±3.46),(21.48±4.85) MPa,A组与B组、C组与D组、A组与C组、B组与D组之间的微拉伸强度差异均具有显著性意义(P < 0.05)。断裂多发生在树脂-牙本质黏接界面。提示无论在正常牙本质还是龋损影响牙本质,全酸蚀黏接剂的黏接强度强于第7代自酸蚀黏接剂;对于同一种黏接剂正常牙本质能获得比龋损牙本质更大的黏接强度。     

Vasorelaxant Effects of Clearfil SE Bond and Clearfil S3 Bond Mediated by Calcium Antagonistic Action

Dental adhesives can alter the contractility of vascular tissue via different mechanisms. The aim of this study was to investigate and compare the vascular action of two self-etch adhesive systems, Clearfil SE Bond (CSEB) and Clearfil S³ Bond (CS3B). Responses of isolated rat thoracic aorta rings were recorded isometrically by force displacement transducers. Following pre-contraction of aorta rings, relaxations to the independent and mixed components of CSEB and CS3B were recorded in the absence and presence of nitric oxide synthase (NOS) inhibitor (N ^ω -nitro-L-arginine methyl ester (N-LAME)), cyclooxygenase (COX) inhibitor (indomethacin) and K⁺ channel inhibitors (tetraethylammonium, glibenclamide and 4-aminopyridine). We also tested the effects of CSEB and CS3B in endothelium-intact and -denuded rat thoracic aorta rings. To investigate the Ca²⁺-channel antagonistic effect of adhesive components, concentration–response curves to CaCl₂ were obtained in the absence and presence of the components. The primer, the bond, and the mixture of CSEB and CS3B elicited concentration-dependent relaxations. Mechanical rubbing of the endothelium did not significantly modify the extent of vasorelaxation induced by the test materials. The vasorelaxant effect was mediated neither by NOS and COX inhibition nor by the tested K⁺ channel antagonists. Mechanical removal of the endothelium did not alter the vasodilatory effect induced by the self-etch adhesives. Both CSEB and CS3B significantly inhibited the contractions induced by CaCl₂. These results demonstrate the vasodilatory effect induced by the self-etch adhesive systems through a Ca²⁺-antagonistic effect.     

Degradation of the resin-dentin bonds after simulated and inhibited cariogenic challenge in an in situ model

The aim of this study was to evaluate the resin-dentin bonds of two simplified etch-and-rinse adhesive after simulated cariogenic and inhibited cariogenic challenge in situ. Dental cavities (4 mm wide, 4 mm long, and 1.5 mm deep) were prepared in 60 bovine teeth with enamel margins. Restorations were bonded with either adhesive Adper Single Bond 2 (3MESPE) or Optibond Solo Plus (Kerr). Forty restorations were included in an intra-oral palatal appliance that was used for 10 adult volunteers while the remaining 20 dental blocks were not submitted to any cariogenic challenge [NC group] and tested immediately. For the simulated cariogenic challenge [C+DA], each volunteer dropped 20% sucrose solution onto all blocks four times a day during 14 days and distilled water twice a day. In the inhibited cariogenic challenge group [C + FA], the same procedure was done, but slurry of fluoride dentifrice (1.100 ppm) was applied instead of water. The restored bovine blocks were sectioned to obtain a slice for cross-sectional Vickers microhardness evaluation and resin-dentin bonded sticks (0.8 mm(2)) for resin-dentin microtensile evaluation. Data were evaluated by two-way ANOVA and Tukey's tests (α = 0.05). Statistically lower microhardness values and degradation of the resin-dentin bonds were only found in the C + DW group for both adhesives. The in situ model seems to be a suitable short-term methodology to investigate the degradation of the resin-dentin bonds under a more realistic condition.     

Influence of adhesive systems and flowable composite lining on bond strength of class II restorations submitted to thermal and mechanical stresses

The purpose of this study was to evaluate the effect of adhesive systems and flowable composite lining on bond strength to gingival margins of Class II restorations after thermal/mechanical stresses. Proximal cavities were prepared in 90 bovine incisors. Teeth were assigned into nine groups (n = 10), according to the combination of bonding agent [Single Bond (SB), Optibond Solo Plus (OP), Prime & Bond NT (NT)] and layer (1 mm) of flowable composite Filtek Flow (FF) [absent, one layer, two layers]. Materials were applied according to manufacturers' instructions, and FF layers were photoactivated separately. Restorations were concluded with composite resin and were submitted to thermal (1000x, 5-55 degrees C) and mechanical stresses (100,000x, 80 N). For microtensile evaluation, slabs from the gingival bonded interface were obtained, tested under tension, and their failure mode was observed by scanning electron microscopy. Bond strength data were analyzed using two-way ANOVA/Tukey's test. No interaction was observed between adhesive systems and FF lining (p = 0.89). Also, no significant difference was found between bond strength values, whether or not FF layers were used (p = 0.33). However, bonding systems demonstrated significant differences (p = 0.01). SB and NT presented means higher than those observed with OP. Fracture modes varied considerably between experimental groups, and a greater frequency of cohesive failures was noted when FF layers were used.     

Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength

The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (μTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL-Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the μTS was determined (n=10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II (p>0.05). For Clearfil SE Bond, the μTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit (p<0.05). Spectrometry revealed that this marked difference must be attributed to a different light transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins.     

CaMKⅡ抑制剂抑制AngⅡ或电场刺激诱导的心肌成纤维细胞TNF-α、TGF-β_1及collagenⅠ、Ⅲ的表达

目的:观察钙-钙调素依赖性蛋白激酶(CaMK)Ⅱ在血管紧张素Ⅱ(AngⅡ)或电场刺激(EFS)诱导的大鼠心肌成纤维细胞增殖、分泌细胞因子及胶原酶表达中的作用及其机制。方法:培养新生1-3 d乳鼠心肌成纤维细胞(3代),分为正常对照组(control)、0.1μmol/L AngⅡ组、0.1μmol/L AngⅡ+0.5μmol/L CaMKⅡ抑制剂KN92组、0.1μmol/L AngⅡ+0.5μmol/L CaMKⅡ抑制剂KN93组、0.1μmol/L AngⅡ+0.5μmol/L CaMKⅡ抑制剂AIP组;10 V1.0 Hz EFS组、10 V 1.0 Hz EFS+0.5μmol/L KN92组、10 V 1.0 Hz EFS+0.5μmol/L KN93组、10 V1.0 Hz EFS+0.5μmol/L AIP组、10 V1.0 Hz EFS+0.1μmol/L AngⅡ组。MTT法测定心肌成纤维细胞增殖;ELISA法测定细胞因子(TGF-β1,TNF-α)分泌;RT-PCR检测TGF-β1、TNF-α、collagenⅠ、ⅢmRNA水平。结果:CaMKⅡ抑制剂(0.5μmol/L KN93,0.5μmol/L AIP)能预防AngⅡ或EFS诱导的心肌成纤维细胞增殖;CaMKⅡ抑制剂(0.5μmol/L KN93,0.5μmol/L AIP)可预防AngⅡ或EFS引起的细胞培养上清液TGF-β1、TNF-α含量及相应mRNA表达增加。CaMKⅡ抑制剂(0.5μmol/L AIP,1.0μmol/L AIP)预防0.1μmol/L AngⅡ引起的collagenⅠ、Ⅲ表达增加。结论:抑制CaMKⅡ对AngⅡ或EFS诱导的心肌成纤维细胞增殖具有预防作用,其机制可能与CaMKⅡ抑制剂抑制TGF-β1、TNF-α以及胶原的表达有关。     

An evaluation of the cytotoxic effects of orthodontic bonding adhesives upon a primary human oral gingival fibroblast culture and a permanent,human oral cancer-cell line

The purpose of this investigation was to determine the cytotoxic effects of three different kinds of orthodontic adhesive on a human primary gingival fibroblast culture (GF) and a human oral cancer-cell line (OC2). The adhesives comprised a self-cure bonding resin, a light-cure bonding resin, and a hybrid glass ionomer. Any differences between the cytotoxic potencies of eluates of the orthodontic materials on GF and OC2 cells were quantified colorimetrically (MTT test). The results are as follows: For the hybrid glass ionomer, the survival rate of GF cells exposed to the liquid component revealed a significant dose-dependent decrease (p < 0.05). The liquid component and the mixed hybrid glass-ionomer material reflected a significant dose-dependent decrease (p < 0.05) in exposed OC2 cell survival. Associated with an increase in the cell exposure concentration of Resin A, Resin B, Paste A, Paste B, Resin A + B, Paste A + B and the set material of the self-cure resin adhesive, was a significant decrease in survival rate for cultured GF and OC2 cells (p < 0.05). Associated with an increase in the concentration of the primer, paste, and mixed material of the light-cure resin adhesive to which test cells were exposed, the survival rate reflected a decrease for GF cells (p < 0.05). The survival rate of cells exposed to light-cure resin paste reflected no difference for OC2 cells. It is concluded that the liquid of the hybrid glass-ionomer cement, Resin A and Resin B and Resin A + B of the self-cure resin and the primer of the light-cure resin are toxic agents to the GF and OC2 cell lines. Primary human gingival fibroblasts were found to be more sensitive than the tested human oral carcinoma cell line from most of the substances.     

An innovative quaternary ammonium methacrylate polymer can provide improved antimicrobial properties for a dental adhesive system

A quaternary ammonium methacrylate polymer (QAMP) with antimicrobial potential was synthesized. The resulting product (QAMP) was characterized by FTIR spectroscopy, NMR spectroscopy, visible spectrophotometry, XRPD and TGA. The in vitro susceptibility tests against Streptococcus mutans of QAMP were investigated prior and after incorporation into a commercial adhesive system (Clearfil? SE Bond). The release of quaternary ammonium compounds from the experimental adhesive system (Clearfil? SE Bond?+?5% QAMP) was performed during 1, 7, 14, 21 and 30 days. Spectroscopic data confirmed that QAMP was successfully obtained. Thermogravimetric analysis indicated that QAMP was heat stable. Prior incorporation into the adhesive system, QAMP revealed an inhibition halo of 18.33?±?0.6?mm. By agar disk diffusion test, Clearfil? SE Bond containing 5% QAMP presented an inhibition halo (16.67?±?1.5?mm) similar to Clearfil? Protect Bond (positive control, 17.00?±?1.7, p?=?0.815) and significantly higher than Clearfil? SE Bond (negative control, 11.00?±?1.0, p?=?0.006). The minimum inhibitory/bactericidal concentrations for Clearfil? SE Bond containing 5% QAMP were 20?μL?mL^?1. The release of quaternary ammonium compounds from the experimental adhesive containing QAMP was very low (5.1%) when compared to Clearfil? Protect Bond that released 47.2% of its quaternary ammonium monomer (MDPB) after 30 days. The QAMP can offer enhanced antimicrobial properties for self-etching adhesive systems.     

Evaluation of the fatigue behavior of the resin-dentin bond with the use of different methods

The clinical performance of directly bonded resin composites is fundamentally dependent on durable adhesion to prevent gap formation over time. The goal of this investigation was to evaluate the effectiveness of various dentin adhesives by means of quasistatic and dynamic dentin bond strengths, and also to determine marginal and internal gap formation after loading in an artificial oral environment. Three hundred thirty human third molars were used within four weeks of extraction. Adhesives used were A.R.T. Bond, OptiBond FL, Scotchbond Multi-Purpose Plus, Single Bond, Prime & Bond NT, and One Up Bond F for bonding of one resin composite (Z 250). Buccal and lingual aspects of 90 teeth were ground flat to expose dentin, then resin composite cylinders were bonded. Initial bond strengths (n = 10) and adhesive fatigue limits (n = 20) were determined with the use of a shear test apparatus. One hundred eighty conical cavities were prepared into dentin discs and filled with the same materials. After 21 days of storage, initial push-out bond strengths (n = 10) and adhesive fatigue limits (n = 20) were measured. Sixty molars with MO cavities (n = 10) with margins below the cement-enamel junction were filled. Before and after thermomechanical loading (100000 x 50 N and 2500 x thermocycling between + 5 and + 55 degrees C), marginal gap formation and internal adaptation (only after loading) were analyzed under a SEM (x 200). The one-bottle systems showed higher shear bond strengths when evaluated statically and dynamically. However, cyclic fatigue push-out bond strengths resulted in higher values for older multistep systems. Marginal and internal gap analysis confirmed the results, in favor of older adhesive systems (p <.05; Mann-Whitney U test).     

Exploration and preliminary clinical investigation of an adhesive approach for primary tooth restoration

The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength (SBS) of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H₃PO₄. SBS and marginal microleakage tests were conducted with Single Bond Universal (SBU)/Single Bond 2 (SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H₃PO₄ pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H₃PO₄ etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12- and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12- and 18-month follow-up assessments. Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.     

Glycosaminoglycan mimetics (RGTA) modulate adult skeletal muscle satellite cell proliferation in vitro

Confocal Raman microspectroscopy (CRM) provides an important and novel means of analyzing the chemical composition of the adhesive/dentin (a/d) interface. The purpose of this study was to develop a method for quantitative determination of the degree of adhesive penetration at the a/d interface using CRM. Three commercial dentin adhesive systems [Scotchbond Multipurpose Plus (SBMP+), Single Bond (SB), and Primer Bond NT (PBNT)] based on the total etch and "wet" bonding technique were examined in this study. Human dentin specimens treated with these adhesives were analyzed with CRM mapping across the a/d interface. Also, Raman spectra were collected on model mixtures of adhesive and type I collagen, and the ratios of the relative intensities of the Raman bands corresponding to adhesive and collagen were used for the construction of calibration curves. By comparing the Raman band ratios of interface specimens to the calibration curves, the percent of adhesive as a function of spatial position across the a/d interface was determined. The results show that there is a gradual decrease in penetration as a function of position for all three adhesive systems while the adhesive concentration gradient decreases in the order of SBMP+ > SB > PBNT. These differences in penetration of the three adhesives at the a/d interface also are discussed relative to the composition and phase segregation in adhesives. Additionally, our results indicate that confocal Raman microspectroscopy is a reliable in situ analytical technique for simple and rapid quantitative determination of adhesive penetration at its interface with prepared dentin.