The adverse effect of commercial dentine‐bonding systems on the skin of guinea pigs

It was widely known that 2‐hydroxyethyl methacrylate (2‐HEMA) can cause contact dermatitis. Commercially available dentine primers and dentine bonding agents that contain 2‐HEMA are widely used. The purpose of this study was to investigate the cumulative irritation and delayed hypersensitivity caused by commercial dentine bonding systems when applied to the skin of guinea pigs. We have concluded that almost no dentine bonding systems cause cumulative irritation, but some commercially available dentine bonding systems may produce delayed hypersensitivity.     

Bonding of restorative materials to dentine

The potential advantages of bonding a filling material to dentine have long been recognized by the dental profession. Such bonding would prevent recurrent decay and would provide a long-lasting restoration. Bonding of suitable filling materials to enamel can be easily accomplished by first etching the enamel with acid. This opens up areas in the enamel and permits filling materials to flow into the openings and form mechanical locks. It is not possible to do this with dentine since the acid used to etch enamel would harm the pulp when applied to dentine. The present status of dentine bonding is that a small number of products are now being marketed with claims of bonding to dentine. In addition, research is being conducted on some experimental products. Results in the laboratory show that the bond strengths achieved by composite resins, using the commercially available materials on dentine, do not reach those obtained with acid etched enamel. The correlation of these results with clinical performance is unknown. Therefore, the amount of available information is at present insufficient to make recommendations on the effectiveness or ineffectiveness of commercially available dentine bonding systems. However, it appears that caution should be employed when using any product requiring an etchant or acidic cleansing agent. There is a need for further research to gain better understanding of the biological safety and effectiveness of both the present commercial and experimental dentine bonding systems.     

An update on the use of resin-based dental adhesives.

The introduction of the acid-tech technique and the development of dentine bonding agents have been major steps forward in adhesive dentistry. However, the adhesion provided by the current dentine bonding resins is still inadequate to withstand many of the stresses encountered in clinical practice. The authors review the adhesive agents currently available, and the published evidence about their performance.     

Adhesion of composite to dentin. Mechanical and clinical results

Although an efficient bond of resin composites to enamel can be realized since quite a long time, reliable dentine bonding is nowadays still a clinical problem. After the failure of the dentine-etch technique, followed by the misfortunes of the chemical dentine adhesion technique, modern dentine adhesive systems are believed to function by a micromechanical attachment mechanism. Based on a morphological study of the resin-dentine interface, a broad selection of dentine adhesive systems was classified following their adhesion-strategy. In a second part, eight dentine adhesive systems were clinically tested in terms of retention.     

Dentine bonding systems: 1. Mode of action

The achievement of a reliable bond to dentine has been more difficult than bonding to enamel, due principally to the anatomy of the dentine substrate. The mechanisms of bonding are now much better understood than a decade ago and clinically-viable bond strengths to dentine are now achieved with many dentine bonding systems.     

Effect of delayed light curing of a resin composite on marginal integrity in cylindrical dentine cavities

The effect of delayed light curing of resin composite on marginal adaptation has been examined by measuring the wall-to-wall polymerization contraction gap when using a commercial resin composite together with experimental dentine bonding systems to restore cylindrical preparations in dentine. Morphological changes in dentine during dentine bonding procedures were observed using a scanning electron microscope. In a previous report, the contraction gap width for a resin composite increased when irradiation of the resin system was delayed, despite the use of a dentine bonding system considered to be ‘contraction’ gap free. Such deterioration in marginal adaptation was minimized by use of an experimental dentine primer, 40% erythritol methacrylate aqueous solution (EM), followed by the use of a commercial dual- or autocured dentine bonding agent. Under scanning electron microscopy, the dentine surface microstructure became unclear after EM priming, and a polymer film was detected after polymerization of the dual-cured dentine bonding agent. The hydrogelled primer and the formation of a polymer network on the dentine surface may prevent the flow of fluid from the pulp through the dentine tubules, and maintain marginal integrity if there is delay in light curing of light-activated resin composite systems.     

An investigation into the quality of dentine bonding systems for accomplishing a durable bond

For a wide variety of dentine bonding systems the bond strength before and after thermocycling was determined on dentine with and without hydraulic tubular pressure. The importance of the hydrophillic nature of several bonding systems could be demonstrated. The dentine smear layer could not prevent a negative effect of water in the tubulus on hydrophobic systems. Removal of the smear layer had a positive effect on the durability of the bond. When loaded until fracture, some bonding systems resisted adhesive failure.     

A laboratory investigation of a composite resin/dentine bonding agent mixture used as a root canal sealer

The objective of this project was to determine the effectiveness of a dentine bonding agent, in conjunction with a composite resin, to act as an endodontic sealing material. The effectiveness was compared with that provided by a conventional sealer (AH26) by measuring dye penetration into the root canal. Two obturation techniques were used with each sealer; the single gutta-percha point technique, and lateral condensation with multiple gutta-percha points. Lateral condensation with the conventional sealer was found to be the superior procedure, by producing the least amount of linear leakage (coronally from the apex) on average. However, the single point technique with the composite resin/dentine bonding agent sealer provided the greatest number of 'no leakage' samples. Scanning electron microscope investigation of obturated roots revealed the presence of resin tags in dentine tubules only in those samples where the composite resin/dentine bonding agent sealer was used. The short working time provided by the composite resin/dentine bonding agent sealer prevented successful obturation using lateral condensation. The provision of an extended working time composition for this sealer may produce more favourable results in obturation with lateral condensation.     

A comparison of the effectiveness of dentine bonding agents

Tensile and shear bond strengths between prepared surfaces of coronal dentine and cores of composite materials using different bonding systems were determined. Control procedures demonstrated that tensile bond strengths were approximately doubled by the use of bonding agents in systems requiring initial cleansing or etching of dentine. Similar increases were found in shear bond strengths. When bonding to different depths of dentine was compared shear and tensile bond strengths to the more occlusal dentine were greater than to more pulpally placed dentine. The factors which appear to affect bond strength under laboratory conditions are: etching of dentine (but beware of this procedure clinically); the smear layer and its removal; polymerization shrinkage of composite materials; the depth and plane of bonded dentine; the use of fresh or stored dentine; and the structure of the treated dentine.     

Adhesive restorative materials: a review

'Adhesive' restorative dentistry originated with the work of Buonocore in 1955 in bonding resin to etched enamel. Since then, adhesive materials and techniques have developed at a rapid rate. The first chemically adhesive material (zinc polycarboxylate cement) was marketed in the late 1960s, and glass-ionomer cements and dentine bonding agents have since become available. This review focuses on the latter two products. Glass-ionomer cements have a particular role in adhesive dentistry because of their reliable chemical adhesion to enamel and dentine, and because of their apparent ability to promote the remineralization of 'affected' dentine. Dentine bonding agents have undergone marked changes in presentation over the last 15 years, but all have an essentially similar bonding system, that of hybrid layer formation. However, the most recent systems have limited clinical data supporting their use.     

Effect of provisional cements on the bond strength of various adhesive bonding systems on dentine

summary Temporization of prepared teeth is needed for protection of the pulp and the restoration of the patients'aesthetic and functional needs. When zinc-oxyphosphate cement is used, eugenol-containing provisional cements are preferred because of their sedative effect to the pulp and because of their acceptable compressive strength. However, prior to definitive adhesive cementation with composite luting resins and dentine bonding agents the use of eugenol-containing provisional cements has to be considered critical because eugenol severely disturbs the polymerization of resinous materials. The purpose of this study was to compare shear bond strength values of various adhesive luting systems on dentine which had been in contact with various provisional cements prior to dentine bonding. The results show that the provisional cements which were used considerably decreased some of the bond strength values of the dentine bonding systems tested. Freegenol® and Fermit®, however, seem to have beneficial effects on the SBS values of Syntac® and ART Bond®. The only bonding system which produces acceptably high average SBS values with a eugenol-containing provisional cement was P-Bond®.     

Treatment of dentinal hypersensitivity using a dentine bonding system

AIMS AND OBJECTIVES: Many agents have been used in treatment of dentinal hypersensitivity in the past, but dentine bonding systems have recently been suggested as being effective. This study examined the effectiveness of a dentine bonding system in the treatment of dentinal hypersensitivity in dental practice conditions. METHODS: Dentists in two dental practices agreed to carry out the project. One practice was in the UK, the other in India. A total of 34 patients who were diagnosed to have dentinal hypersensitivity were treated using the dentine bonding system. Patients were requested to record their perception of their pain on a 100mm linear scale, pre-treatment, one day and one week post-treatment. RESULTS: All patients experienced relief of pain, both 1 day and 1 week after treatment. Profile plots of the patients' perceived pain scores for the two practices separately indicated that there was a general trend across both practices for these to fall quite sharply one day after treatment and then generally level out one week post-treatment. There was evidence indicating a possible difference in pain perception in the two communities from which the patients were drawn. CONCLUSION: The dentine bonding system evaluated was successful in reducing the pain of dentinal hypersensitivity, at least in the short term.     

Bond strengths of eight contemporary adhesives to enamel and to dentine: an in vitro study on bovine primary teeth

OBJECTIVES: The aim of this study was to compare the shear and tensile bond strengths of eight adhesive systems to the enamel and dentine of primary bovine teeth. METHODS: Two hundred and fifty-six noncarious bovine mandibular primary incisors were collected and stored in an aqueous 1% chloramine solution at room temperature for no longer than 3 months after extraction. The tested adhesives were: Clearfil SE bond (SE); Adper Prompt L Pop (LP); Optibond Solo Plus Self-etch (OB); AdheSE (AS); Xeno III (XE); Scotch Bond 1 (SB); Etch & Prime 3.0 (EP); and I Bond (IB). For the shear bonding test and the tensile bonding test, the labial surfaces of primary incisors were used. To obtain a flat surface, the labial surfaces of the teeth were sanded on wet silicon carbide paper, first with number 200 grit for 20 s and then with number 600 grit for 60 s (n = 128; 64 for shear bonding and 64 for tensile bonding). The results were compared with an analysis of variance and Bonferroni's multiple comparison test. RESULTS: Shear bond strength values ranged from 18.1 to 8.9 MPa on enamel (in decreasing order, SE, LP, OB, AS, XE, SB, EP and IB), and from 17.8 to 8.2 MPa on dentine (in decreasing order, SE, SB, OB, AS, XE, LP, IB and EP). Tensile bond strength values ranged from 13.1 to 6.7 MPa on enamel (in decreasing order, SE, OB, AS, LP, XE, IB, SB and EP), and from 12.1 to 5.7 MPa on dentine (in deceasing order, SE, SB, OB, AS, XE, LP, IB and EP). The differences in bond strengths between the eight systems on enamel and dentine were all statistically significant. This was true for both the shear and tensile bond strengths. CONCLUSIONS: The highest shear bond strength was achieved by SE on enamel and dentine, and the lowest by IB on enamel and EP on dentine. The highest tensile bond strength was obtained by SE on enamel and dentine, and the lowest by EP. Shear bond strengths were significantly higher on enamel when compared to dentine for five of the eight adhesives systems, and tensile bond strengths were significantly higher on enamel when compared to dentine for all but two systems.     

Microleakage of glass ionomer/composite resin restorations: a laboratory study. Part 2. The influence of bonding systems

Acid-etching and bonding of composite resin to bevelled enamel margins has been reported to produce a reliable seal. However, achieving a seal with dentine and cementum margins is more difficult. Four different dentine bonding systems were used in combination with Silux composite resin to restore cervical cavities in vitro. None of the bonding systems used completely sealed either the occlusal or gingival margins. Of the four systems, GLUMA provided the best seal at both the occlusal and gingival margins.     

ENAMEL BONDING WITH SELF-ETCH RESINS

Resin adhesion has revolutionized restorative dentistry because it allows conservative preparations and bonding of various substrates to the tooth structure. Until recently all adhesive systems used an etching agent prior to the priming and bonding steps. Despite excellent clinical and laboratory test results for these three-step systems, simplified adhesive systems were desired and consequently developed to reduce the number of steps during the bonding procedure. Currently there are essentially two philosophies of simplification: the total-etch systems, with a separate etchant and a primer/adhesive; and the self-etching systems, which combine etching and priming in one bottle and have a separate adhesive agent or which combine all three steps in a single solution and application. Unfortunately, despite simplification of bonding products, technique sensitivity, substrate variability, and concerns about enamel bonds have increased. This Critical Appraisal addresses a primary concern about self-etching primers: enamel bonding.     

Marginal gap formation of composites in dentine: effect of water storage

This study investigated the effects of water storage on the marginal adaptation of two composite resins (Spectrum TPH and Ariston AT), two polyacid-modified composite resins (Dyract AP and F2000) and a new PRG composite (Reactmer) to dentine over time. Two cylindrical dentine cavities (1.5 mm diameter and 1.5 mm deep) were prepared on the horizontally sectioned surfaces of freshly extracted teeth. In each tooth, one cavity was restored using composites with their respective bonding system and the other without the bonding system. The sample size for each material with/without bonding system was 6. The composites were placed in one increment, bulk-polymerized, immediately finished/polished with the Sof-lex discs system and fine polished on 30 microm silicon carbide/9 microm aluminium oxide lapping film discs in a microgrinding system. The specimens were then stored in distilled water at 37 degrees C and the maximum marginal gap width between the material and the dentine wall was determined at 24 h, 1 week, 2 weeks, 3 weeks and 4 weeks using a measurescope at x500 magnification. Results were subjected to statistical analysis using monva, anova/Scheffe's post hoc test and independent samples of t-test at significance level 0.05. At all time intervals, no significant difference in marginal gap formation was observed between materials. Where bonding systems were not used, a decrease in gap widths over time was observed with most materials but only Dyract AP exhibited a significant decrease. The latter was observed after 2 weeks storage in water. The use of bonding systems reduced dentine marginal gaps significantly and is therefore mandatory for all composites evaluated. Marginal gaps arising from polymerization contraction of conventional, polyacid-modified and PRG composites cannot be fully compensated by hydroscopic expansion. Clinical relevance Bonding systems are mandatory for all composites when bonding to dentin. In the event of a bond failure at placement, hygroscopic expansion of composites can reduce marginal gaps but not completely.     

Bond strengths of nine current dentine adhesive systems to primary and permanent teeth

The aim of this study was to compare the shear bond strength (SBS) of nine dentine bonding systems (DBS) of different classes to human primary and permanent dentine. Flat dentine occlusal surfaces were produced on human molars (100 primary, 100 permanent) by wet grinding on a 800-grit SiC paper. Nine DBS were applied following the manufacturers' instructions: One total etch multi-step system: Scotchbond Multipurpose Plus (3M/ESPE); Four total etch one-bottle system: Prime &Bond 2.1 (Dentsply), One Step (Bisco), Scotchbond 1 (3M/ESPE), and OptibondSolo Plus (Kerr); Three two-step self-etching primer systems: Clearfil Liner Bond 2 (Kuraray), Clearfil SE Bond (Kuraray), and Prime &Bond NT with NRC (Dentsply); An 'all-in-one' self-etching system: Prompt L-Pop (3M/ESPE). Composite (Z100; 3M/ESPE) cylinders (2 mm diameter, 3 mm high) were polymerized on the treated dentine surfaces and the specimens were stored at 37 degrees C for 24 h prior to testing. Twenty experimental groups were produced and tested. Statistical analysis revealed both a substrate and a bonding system effect. Two adhesive systems (One Step, Prime &Bond NT) had significantly higher bond strengths on permanent than on primary dentine. There was an effect of dentine bonding system on the mode of fracture. Although eight of the 10 DBS tested exhibited higher median SBS values on permanent dentine than on primary dentine, the dependent pairwise comparison identified a significant difference only for two groups. The use of simplified bonding systems does not necessarily result in improved bond strength to primary or to permanent dentine.     

Influence of light irradiation of dentine primers on dentine-resin bond

Objective: The purpose of this study was to examine the influence of light irradiation of dentine primers that contain camphoroquinone (CQ) on the shear bond strength to dentine and their contact angle.

Method: Three dentine bonding systems which contain CQ, Imperva Bond, OptiBond and XR-Bond; and Light Bond, which does not contain CQ, were employed. Labial surfaces of freshly extracted lower bovine incisors were ground with no. 600 grit SiC paper. Dentine primers were applied to the dentine surfaces in two groups, irradiated and non-irradiated. A shear bond strength test was performed and the direct contact angle was measured.

Results: Statistical analysis (Newman-Keuls multiple comparison P < 0.05) of the data indicated that light irradiation of the dentine primer for systems containing CQ resulted in increased bond strength and decreased contact angle.

Conclusion: This study indicates that for these dentine bonding systems containing CQ in their primers, light irradiation of the dentine primer is effective in improving wettability and increasing the bond strength to dentine.     

Current perspectives on dental adhesion: (2) Concepts for operatively managing carious lesions extending into dentine using bioactive and adhesive direct restorative materials

This article reviews the current concepts for operatively managing carious lesions extending into dentine with minimal removal of tooth structure and restoring with dentine adhesives and direct composite resin. It looks sequentially at the operative steps involved including remineralisation with bioactive cements, bonding to caries-affected dentine including smear-layer modification using HOCl, creation of an acid-base resistance zone,steps to optimise the performance of all-in-one adhesives, and incremental placement of direct composite resin to improve bond strengths to cavity floor dentine. It explores how understanding the phenomenon of colour-shifting at the composite resin-enamel/dentine restoration borders can help in creating near “invisible” restoration margins through a “chameleon” effect. With the increased risks of transmission of Covid-19 when aerosol generating procedures are carried out in Dentistry, following a minimally invasive approach to managing dental caries should be given serious consideration.     

Bonding of restorative resins to dentine: status of dentine adhesives and impact on cavity design and filling techniques

In conjunction with the acid etch technique for bonding of restorative resins to enamel, an effective bonding to dentine would eliminate the need for retentive undercuts and ensure a tight marginal seal. Bonding to dentine can be achieved through dentine adhesives. These may be divided into Ca2+-bonding and collagen-bonding types. Several Ca2+-bonding adhesives are based on phosphate methacrylates. Adhesives of this type mediate a bond strength to dentine not exceeding 10 MPa. In contrast, Bowen's bonding system and the Gluma system yield bond strengths higher than 10 MPa. The two latter systems have recently been conceived in simplified versions. In general, the higher the bond strength to dentine mediated by an adhesive, the smaller are the marginal gaps formed by a composite resin polymerizing in a dentine cavity treated by the adhesive. The size and the shape of the cavity influence the width of the marginal gaps. A cavity having a V-shape gives rise to smaller gaps than box-shaped cavities. A filling technique with two 'inclining' layers reduces the width of marginal gaps. Combination of certain Ca2+-bonding and collagen-bonding adhesives results in increased bond strength and smaller marginal gaps.