Three-year clinical performance of a HEMA-free one-step self-etch adhesive in non-carious cervical lesions

Despite the fact that one-step adhesives are currently used routinely in clinical practice, long-term studies on their clinical performance are scarce. The objective of this randomized controlled clinical trial was to test the hypothesis that a 2-hydroxyethyl methacrylate (HEMA)-free one-step self-etch adhesive performs worse than a conventional multistep etch-and-rinse adhesive. Two-hundred and seventy-six non-carious cervical lesions in 52 patients were restored with a micro-hybrid composite (Gradia Direct; GC). These restorations were bonded in random order either with the HEMA-free one-step adhesive G-Bond (GC) or with the 'gold-standard' (control) three-step adhesive Optibond FL (Kerr). The restorations were evaluated after 6, 12, 24, and 36 months of clinical service regarding retention, marginal adaptation, microleakage, caries occurrence, and sensitivity. After a medium-long period of 3 yr, similar success in clinical performance was observed for the simplified all-in-one adhesive and the conventional three-step adhesive. However, the one-step adhesive exhibited significantly more incisal marginal defects and discolorations. Whereas marginal degradation appeared to arrest for the multistep etch-and-rinse adhesive after 12 months, the enamel margins of the restorations bonded with the one-step self-etch adhesive continued to deteriorate. These incisal marginal defects were, however, small and could easily be removed by polishing. For both adhesives, large and sclerosed lesions appeared to be at higher risk of retention loss.     

One-day bonding effectiveness of new self-etch adhesives to bur-cut enamel and dentin

Self-etch adhesives try to solve difficulties commonly associated with the clinical application of etch-and-rinse adhesives. Their application procedure is considered less time-consuming and, more importantly, less technique-sensitive. The main objective of this study was to determine the bonding effectiveness to and the interaction with enamel/dentin of three contemporary one- and two-step self-etch adhesives by microtensile bond strength testing (microTBS), Fe-SEM and TEM when compared to a control two-step self-etch and a three-step etch-and-rinse adhesive. The one-step self-etch adhesive, Adper Prompt (3M ESPE), scored the lowest microTBS of all experimental and control adhesives tested. Conversely, the two-step self-etch adhesives Clearfil SE (Kuraray) and OptiBond Solo Plus Self-Etch (Kerr) approached the values obtained by the three-step etch-and-rinse control (OptiBond FL, Kerr) when bonded to enamel and dentin. Ultramorphological characterization showed that interfacial morphology and the pH of the self-etch primer/adhesive are strongly associated. The interaction with dentin varied from the formation of a submicron, hydroxyapatite-containing hybrid layer for the "mild" self-etch adhesive Clearfil SE to a 3-5 microm thick, hydroxyapatite-depleted hybrid layer for the "strong" self-etch adhesive Adper Prompt. The two-step self-etch adhesives AdheSE and OptiBond Solo Plus Self-Etch presented with a hybrid layer with a hydroxyapatite-depleted top part and a hydroxyapatite-containing base part and were therefore classified into a new group of self-etch adhesives, namely "intermediary strong" self-etch adhesives.     

Adhesives for the restoration of non-carious cervical lesions: a systematic review

ObjectivesTo establish whether simplified adhesives (self-etch) are as clinically effective as conventional adhesives (etch-and-rinse) with multiple application steps for treatment of non-carious cervical lesions (NCCLs).Null hypothesis: there is no difference in the clinical effectiveness of the four different bonding strategies: Three-step etch-and-rinse; Two-step etch-and-rinse; Two-step self-etch; One-step self-etch for treatment of NCCLs.SourcesElectronic databases were searched including: Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. In addition, studies were identified by handsearching of selected journals.Study selectionRandomised controlled trials (RCTs) comparing at least two adhesives in non-carious cervical lesions (NCCLs), with at least 18 months follow-up were selected. The primary outcome was loss of retention/restoration loss, with marginal adaptation and marginal discolouration as secondary outcomes. Criteria for quality assessment included: random sequence generation; allocation concealment; blinding of outcome assessment; and information on withdrawals. Twenty six studies were identified that met the inclusion criteria. In general, studies were not of sufficient quality to fully address the objectives of this review.ConclusionThere is not enough evidence to support one adhesive or bonding strategy over another for treatment of NCCLs. Consequently, the null hypothesis of no difference cannot be supported or rejected with the data currently available. There is a need for better standardisation and reporting of randomised controlled trials investigating adhesive performance.Clinical significanceStudies with low overall risk of bias demonstrated good clinical performance for adhesives with all four bonding strategies. However, included studies showed wide variation between adhesives of the same category.     

Clinical effectiveness of a one-step self-etch adhesive in non-carious cervical lesions at 2 years

A 2-year randomized, controlled prospective study evaluated the clinical effectiveness of a one-step self-etch adhesive and a “gold-standard” three-step etch-and-rinse adhesive in non-carious Class-V lesions. The null hypothesis tested was that the one-step self-etch adhesive does perform clinically equally well as the three-step etch-and-rinse adhesive. A total of 161 lesions in 26 patients were restored with Clearfil AP-X (Kuraray). The restorations were bonded either with the “all-in-one” adhesive Clearfil S3 Bond (Kuraray) or with the three-step etch-and-rinse adhesive Optibond FL (Kerr). The restorations were evaluated at baseline and after 6 months, 1 and 2 years, regarding their retention, marginal adapation, marginal discoloration, caries occurrence, preservation of tooth vitality and post-operative sensivity. Retention loss, severe marginal defects and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. The recall rate at 2 years was 93.8%. Only one Clearfil S3 Bond restoration was lost at the 2-year recall. All other restorations were clinically acceptable. The number of restorations with defect-free margins decreased severely during the 2-year study period (to 6.7% and 25.3% for Clearfil S3 Bond and Optibond FL, respectively). The Clearfil S3 Bond restorations presented significantly more small marginal defects at the enamel side than the Optibond FL restorations (Clearfil S3 Bond: 93.3%; Optibond FL: 73.3%; p = 0.000). Superficial marginal discoloration increased in both groups (to 53.3% and 36% for Clearfil S3 Bond and Optibond FL, respectively) and was also more pronounced in the Clearfil S3 Bond group (p = 0.007). After 2 years, the simplified one-step self-etch adhesive Clearfil S3 Bond and the three-step etch-and-rinse adhesive Optibond FL were clinically equally successful, even though both adhesives were characterized by progressive degradation in marginal integrity. Clearfil S3 Bond exhibited more small enamel marginal defects and superficial marginal discolorations.

     

Retention of tooth-colored restorations in non-carious cervical lesions—a systematic review

Objectives

The aim of this review was to assess the effect of different adhesive systems and tooth preparation on the retention of tooth-colored restorative materials placed in non-carious cervical lesions (NCCLs).

Methods

Randomized clinical trials with a minimum of 3 years of follow-up that evaluated the effectiveness of tooth-colored materials, adhesive systems, and preparation techniques for the restoration of NCCLs were selected. The Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE (OVID), the Latin American and Caribbean Health Sciences Literature database (LILACS), and Medline (OVID) electronic databases were searched from 1990 to 2013.

Results

Twenty-seven randomized clinical trials were included and reviewed. Meta-analysis was used to determine the relative risk of loss of tooth-colored NCCL restorations between different categories of adhesive systems. The effect of tooth preparation could not be similarly analyzed.

Conclusion

The current best evidence indicates that a glass ionomer cement has a significantly lower risk of loss of a NCCL restoration compared to either a three-step etch-and-rinse or a two-step etch-and-rinse adhesive system; a three-step etch-and-rinse adhesive system has a significantly lower risk of loss of a NCCL restoration compared to a two-step etch-and-rinse adhesive system. No significant difference could be observed in the risk of loss of a tooth-colored NCCL restoration between a three-step etch-and-rinse adhesive system and either a two-step self-etch or a one-step self-etch adhesive system.     

Extension of a one-step self-etch adhesive into a multi-step adhesive.

One-step self-etch adhesives are undoubtedly the most user-friendly adhesives, but have been associated with lower bonding effectiveness as compared to two-step and three-step adhesives. Conversion of a one-step self-etch system into a two-step self-etch adhesive by adding a bonding step, or into a three-step etch&rinse adhesive by adding a beforehand etching step and a bonding step might be tempting in order to improve bond strength. OBJECTIVES: The objective of this study was to investigate whether adding application steps influences the bond strength of a one-step self-etch adhesive. METHODS: In this study, the bonding effectiveness of two experimental one-step self-etch adhesives and three different commercial adhesives to enamel and dentin was determined using a micro-tensile bond-strength protocol. This procedure was repeated for the experimental adhesives transformed into two-step self-etch and three-step etch&rinse adhesives. In addition, their interaction with tooth tissue was investigated using TEM and Feg-SEM. RESULTS: Transforming a one-step into a two-step self-etch adhesive did improve the bond strength to enamel and dentin, though not significantly. By adding a preceding etching step, the bond strength to enamel was significantly improved, but that to dentin was decreased considerably. The latter must be attributed to hampered resin infiltration of the one-step self-etch adhesive within the relatively deeply exposed collagen fibril network. SIGNIFICANCE: Additional application of a hydrophobic bonding agent slightly improved bonding effectiveness. Adding a preceding etching step is beneficial for enamel but should be avoided for dentin as this will decrease bond strengths, and may even jeopardize the bonding durability.     

Current aspects on bonding effectiveness and stability in adhesive dentistry

Improved dental adhesive technology has extensively influenced modern concepts in restorative dentistry. In light of minimal-invasive dentistry, this new approach promotes a more conservative cavity design, which basically relies on the effectiveness of current enamel-dentine adhesives. Nowadays, the interaction of adhesives with the dental substrate is based on two different strategies, commonly described as an etch-and-rinse and a self-etch approach. In an attempt to simplify the bonding technique, manufacturers have decreased the number of steps necessary for the accomplishment of the bonding procedure. As a consequence, two-step etch-and-rinse and one-step (self-etch) adhesives were introduced and gained rapid popularity in the dental market due to their claimed user-friendliness and lower technique sensitivity. However, many concerns have been raised on the bonding effectiveness of these simplified adhesives, especially in terms of durability, although this tends to be very material dependent. In order to blend all the adhesive components into one single solution, one-step adhesives were made more acidic and hydrophilic. Unfortunately, these properties induce a wide variety of seemingly unrelated problems that may jeopardize the effectiveness and stability of adhesion to the dental substrate. Being more susceptible to water sorption and thus nanoleakage, these adhesives are more prone to bond degradation and tend to fail prematurely as compared to their multi-step counterparts. Incidentally, another factor that may interfere with the bonding effectiveness of adhesives is the technique used for caries removal and cavity preparation. Several tools are on the market today to effectively remove carious tissue, thereby respecting the current trend of minimum intervention. Despite their promising performance, such techniques modify the tooth substrate in different aspects, possibly affecting bonding effectiveness. Altogether, we may conclude that not only the adhesive formulation, but also substrate nature must be taken into account to achieve a stable bonding interface, rendering the restorative treatment more predictable in terms of clinical performance. In this review, we analyse the current theoretical and clinical aspects of adhesion to enamel and dentine, and discuss the diverse possibilities to overcome problems which nowadays still challenge clinicians in their achievement of a more stable and effective bond to tooth enamel and dentine.     

Clinical long-term retention of etch-and-rinse and self-etch adhesive systems in non-carious cervical lesions. A 13 years evaluation.

OBJECTIVES: The aim of this study was to evaluate the clinical long-term retention to dentin of seven adhesive systems. METHODS: A total of 337 Class V restorations of three three-step etch-and-rinse, one two-step etch-and-rinse and three self-etch adhesive systems were placed in non-carious cervical lesions without intentional enamel involvement. The restorations were evaluated at baseline and then every 6 months during a 13 years follow-up. Dentin bonding efficiency was determined by the percentage of lost restorations. RESULTS: During the 13 years, 275 restorations could be evaluated. The cumulative loss rate at 13 years was 60.3%, with significant different failures rates for the different systems varying between 26.3 and 94.7%. Three materials fulfilled the ADA 18 months full acceptance criteria. Three systems showed already at 18 months or earlier catastrophical debonding rates. The annual failure rates for the three-step etch-and-rinse systems were: Allbond 2 4.1%, Clearfil LB 2.0% and Denthesive 7.3%. For the two-step etch-and-rinse Gluma 2000 6.5%, and for the self-etch systems ART 3.2%, Denthesive 2 5.7% and PUB 3 4.5% CONCLUSION: A continuous degradation of the resin-dentin bond was observed for all bonding systems during the follow-up expressed by the increasing loss rates. A wide variation of dentin bonding effectiveness was seen between the systems independent to adhesion strategy.     

A randomized controlled clinical trial of a HEMA-free all-in-one adhesive in non-carious cervical lesions at 1 year

OBJECTIVES: One-step self-etch adhesives are the most recent generation of adhesives introduced onto the market. The objective of this randomized controlled clinical trial was to test the hypothesis that a one-step self-etch adhesive performs equally well as a conventional three-step etch&rinse adhesive (gold standard). METHODS: Fifty-two patients had 267 non-carious cervical lesions restored with Gradia Direct Anterior (GC). These composite restorations were bonded either with the 'all-in-one' adhesive G-Bond (GC) or with the three-step etch&rinse adhesive Optibond FL (Kerr). The restorations were evaluated after 6 and 12 months clinical service regarding their retention, marginal integrity and discoloration, caries occurrence, preservation of tooth vitality and post-operative sensitivity. Retention loss, severe marginal defects and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. A logistic regression analysis with generalized estimating equations was used to account for the clustered data (multiple restorations per patient). RESULTS: The recall rate at 1 year was 98%. The statistical analysis revealed a relatively low patient factor, indicating that supplementary information could be obtained from the additional restorations placed per patient. The retention rate for G-Bond was 98.5% compared to 99.3% for Optibond FL, due to the retention loss of two and one restorations, respectively. There were no significant differences between the two adhesives regarding the evaluated parameters except for the presence of small enamel marginal defects with G-Bond. CONCLUSIONS: After 12 months, the simplified one-step G-Bond and the three-step Optibond FL were clinically equally successful, even though both adhesives were characterized by progressive degradation of marginal adaptation, and G-Bond exhibited more small enamel marginal defects.     

Four-year clinical evaluation of Class II nano-hybrid resin composite restorations bonded with a one-step self-etch and a two-step etch-and-rinse adhesive

Objective

The objective of this prospective clinical trial was to evaluate the 4-year clinical performance of an ormocer-based nano-hybrid resin composite (Ceram X; Dentsply/DeTrey) in Class II restorations placed with a one-step self-etch (Xeno III; Dentsply/DeTrey) and two-step etch-and-rinse adhesive (Ivoclar Vivadent).

Methods

Seventy-eight participants received at random at least two, as similar as possible, Class II restorations of the nano-hybrid resin composite bonded with either a single step self-etch adhesive or a control 2-step etch-and-rinse adhesive. The 165 restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 4 years.

Results

162 restorations were evaluated at 4 years. Postoperative sensitivity was observed in 6 patients (3 Xeno III, 3 Exite) between 1 and 3 weeks. Eleven failed restorations (6.8%) were observed during the follow up. Seven in the one-step self-etch adhesive group (7.7%) and four in the 2-step etch-and-rinse group (5.6%). This resulted in non-significant different annual failure rates of 1.9% and 1.4%, respectively. Fracture of restoration was the main reason for failure.

Conclusion

The ormocer-based nano-hybrid resin composite showed a good clinical performance in Class II cavities during the 4 year evaluation. No significant difference was seen in overall clinical effectiveness between the two adhesives.     

Dental adhesion review: aging and stability of the bonded interface.

OBJECTIVE: Most of current dental adhesive systems show favorable immediate results in terms of retention and sealing of bonded interface, thereby counteracting polymerization shrinkage that affects resin-based restorative materials. Despite immediate efficacy, there are major concerns when dentin bonded interfaces are tested after aging even for short time period, i.e. 6 months. METHODS: This study critically discusses the latest peer-reviewed reports related to formation, aging and stability of resin bonding, focusing on the micro and nano-phenomena related to adhesive interface degradation. RESULTS: Most simplified one-step adhesives were shown to be the least durable, while three-step etch-and-rinse and two-step self-etch adhesives continue to show the highest performances, as reported in the overwhelming majority of studies. In other words, a simplification of clinical application procedures is done to the detriment of bonding efficacy. Among the different aging phenomena occurring at the dentin bonded interfaces, some are considered pivotal in degrading the hybrid layer, particularly if simplified adhesives are used. Insufficient resin impregnation of dentin, high permeability of the bonded interface, sub-optimal polymerization, phase separation and activation of endogenous collagenolytic enzymes are some of the recently reported factors that reduce the longevity of the bonded interface. SIGNIFICANCE: In order to overcome these problems, recent studies indicated that (1) resin impregnation techniques should be improved, particularly for two-step etch-and-rinse adhesives; (2) the use of conventional multi-step adhesives is recommended, since they involve the use of a hydrophobic coating of nonsolvated resin; (3) extended curing time should be considered to reduce permeability and allow a better polymerization of the adhesive film; (4) proteases inhibitors as additional primer should be used to increase the stability of the collagens fibrils within the hybrid layer inhibiting the intrinsic collagenolytic activity of human dentin.     

Polymerization kinetics of dental adhesives cured with LED: correlation between extent of conversion and permeability.

OBJECTIVES: The aim of this study was to analyze the polymerization kinetics of different adhesive films in relation to their permeability after exposure to different LED curing units. METHODS: One adhesive from each class was analyzed: a three-step etch-and-rinse (OptiBond FL; Sybron-Kerr), a two-step etch-and-rinse (One-Step, Bisco), a two-step self-etch (Clearfil Protect Bond, Kuraray) and a one-step self-etch adhesive (Xeno III; Dentsply DeTrey). Adhesive films were prepared and cured with SmartLite IQ (Dentsply) or L.E.Demetron I (Demetron Kerr) up to complete curing. Polymerization kinetic curves of the tested adhesives were obtained with differential scanning calorimetry (DSC). In particular, total reaction time and extent of polymerization (Ep) at 20, 40 or 60s were compared. Permeability of the adhesive films was evaluated on flat dentin surfaces of human extracted teeth connected to a permeability device and statistically analyzed. RESULTS: Total reaction time differed among the adhesives tested: OptiBond FL相似文献   

A randomized controlled study evaluating the effectiveness of a two-step self-etch adhesive with and without selective phosphoric-acid etching of enamel.

OBJECTIVES: The purpose of this randomized controlled clinical trial was to test the hypothesis that a two-step self-etch approach is equally effective to restore cervical class-V lesions as a self-etch approach with beforehand selective etching of enamel using phosphoric acid. METHODS: Twenty-nine patients received two or four restorations randomly following two experimental protocols ('paired-tooth' study design): (1) A 'mild' self-etch adhesive (Clearfil SE, Kuraray) was applied following a self-etch approach on both enamel and dentin (C-SE non-etch); (2) Similar application of Clearfil SE, but including beforehand selective acid-etching of the enamel cavity margins with 40% phosphoric acid (C-SE etch). Clearfil AP-X (Kuraray) was used as restorative composite for all 100 restorations. The clinical effectiveness was recorded in terms of retention, marginal integrity and clinical micro-leakage after 2 years of clinical service. RESULTS: No restoration losses were recorded. Clinical micro-leakage was slight and only rarely observed. No significant differences were found between both groups for the diverse parameters evaluated except for the number of small incisal marginal defects, which was significantly higher in the C-SE non-etch group (McNemar: p = 0.0391). SIGNIFICANCE: The clinical effectiveness of the mild two-step self-etch adhesive Clearfil SE was excellent after 2 years of clinical service. Although in general no difference in clinical performance was recorded when Clearfil SE was applied following either of the experimental protocols, more marginal defects at the enamel side were noticed when enamel was not beforehand etched with phosphoric acid. However, these defects were small and of clinically negligible relevance.     

Bonding effectiveness of a new 'multi-mode' adhesive to enamel and dentine

ObjectivesSelf-etch adhesives are well adopted in general practice, obviously primarily thanks to their ease of use and fast application time. Nevertheless, phosphoric acid is still often recommended to beforehand etch enamel following a so-called ‘selective’ enamel-etch technique, this in particular when most cavity margins end in enamel. The purpose of this study was to test if a new one-step adhesive can be applied in a multi-mode manner, this following different, either ‘full’ or ‘selective’, self-etch and etch-and-rinse approaches. Specific research hypotheses tested were that prior phosphoric-acid etching did not affect the bonding effectiveness of the one-step adhesive to enamel and dentine, and that the bonding effectiveness to dentine was also not affected when the adhesive was applied either following a ‘dry-bonding’ or ‘wet-bonding’ etch-and-rinse technique.MethodsThe micro-tensile bond strength (μTBS) of the one-step self-etch adhesive G-Bond Plus (GC, Tokyo, Japan; 1-SEA) was measured when it was bonded to bur-cut enamel following either a ‘self-etch’ or an ‘etch-and-rinse’ adhesive protocol, and to bur-cut dentine when applied following either a ‘self-etch’, a ‘dry-bonding’ or a ‘wet-bonding’ etch-and-rinse adhesive protocol. Bond-strength testing was corroborated by ultra-structural analysis of the interfacial interaction at enamel and dentine using transmission electron microscopy (TEM).ResultsPrior phosphoric-acid etching significantly increased the bonding effectiveness of the 1-SEA to enamel. A clearly enhanced micro-retentive surface was revealed by TEM. To dentine, no statistically significant difference in bonding effectiveness was recorded when the 1-SEA was either applied following a self-etch or both etch-and-rinse approaches. The ‘dry-bonding’ etch-and-rinse protocol was significantly more effective than its ‘wet-bonding’ version. TEM however revealed indications of low-quality hybridisation following both etch-and-rinse approaches, in particular in the form of a porous and poorly resin-infiltrated collagen mesh.ConclusionsWhile phosphoric-acid etching definitely improved bonding of the one-step self-etch adhesive to enamel, one should be more careful with additional phosphoric-acid etching of dentine. Although the bond strength was not reduced, the resultant adhesive interface appeared ultra-structurally more vulnerable to biodegradation.     

An 18-months' evaluation of self-etch and etch & rinse adhesive in non-carious cervical lesions

OBJECTIVE. In this intra-individual comparison (an 18-months' randomized, controlled prospective study), we evaluated the clinical performance of one self-etch and one "etch & rinse" adhesive in non-carious cervical lesions. METHODS. Twenty-five patients with at least two pairs of similar-sized non-carious cervical lesions participated. Seventy-eight restorations were placed; 39 with etch & rinse (Single-Bond) and 39 with self-etch (Adper Prompt). Both adhesives were combined with the microfilled resin composite Filtek-A110. The restorations were evaluated at baseline, 6, 12, and 18 months according to slightly modified USPHS criteria. Statistical differences between the adhesives was tested with McNemar's test and clinical degradation over time for each material with the Fisher exact test (a=0.05). RESULTS. Thirty pairs were evaluated at 12 and 18 months. Two self-etch restorations were lost after 18 months. Nine Adper Prompt and four Single-Bond restorations scored bravo for marginal adaptation at 18 months (p<0.05). Nine Adper Prompt and three Single-Bond restorations scored bravo for marginal discoloration (p<0.05). CONCLUSIONS. Both adhesive systems showed acceptable clinical retention rates according to the ADA full acceptance criteria for enamel-bonding systems in class V non-carious lesions. The self-etch adhesive showed a faster progressive marginal degradation.     

New developments in dental adhesion

Numerous simplified adhesives have been introduced to the dental market within the last few years, sometimes without comprehensive testing to validate the performance claimed by the respective manufacturers. Mild self-etch adhesives are unable to etch enamel to provide adequate retention for bonded restorations. Although high early resin-dentin bond strength values can be achieved with some self-etch adhesives, their resistance to thermal and mechanical stresses over time is disappointing. In light of the current drawbacks attributed to all-in-one self-etch adhesives, etch-and-rinse adhesives are still the benchmark for dental adhesion in routine clinical use. This article summarizes current issues and factors related to the performance of adhesives.     

Five-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions

Objectives

The objective of this randomized controlled trial was to evaluate the clinical performance of a 2-hydroxyethyl methacrylate (HEMA)-free one-step adhesive.

Materials and methods

Two hundred sixty-seven cervical lesions in 52 patients were restored with the composite Gradia Direct (GC), bonded with either the one-step self-etch adhesive G-Bond (GC) or the three-step etch-and-rinse adhesive Optibond FL (Kerr) in a random order. The restorations were evaluated for retention, marginal integrity, marginal discoloration, and caries occurrence after 5 years. Specific statistics were used to account for the clustered data (multiple restorations per patient).

Results

The clinical success rate for G-Bond (87.4 %) was not significantly different from that of Optibond FL (90.9 %). Both adhesives showed progressive marginal deterioration, but G-Bond exhibited more small enamel defects and marginal discoloration, and unlike previous recalls, several restorations failed because of deep microleakage. Large sclerotic lesions were a significant risk factor for retention loss with G-Bond. Irrespective of the adhesive, almost all restorations with retention loss were located in the lower jaw.

Conclusion

After 5 years of clinical service, restorations bonded with the HEMA-free one-step adhesive did not need repair or replacement more often than those with the three-step etch-and-rinse adhesive, and both adhesives had a high retention rate (>90 %). There were indications that G-Bond did not (self-)etch enough in some clinical situations, as G-Bond exhibited more incisal defects and marginal discolorations, and sclerotic lesions were at higher risk of retention loss.

Clinical relevance

The clinical performance of the HEMA-free one-step adhesive was clinically acceptable after 5 years.     

Effect of cavity configuration and aging on the bonding effectiveness of six adhesives to dentin.

OBJECTIVES: The purpose of this study was to determine the effect polymerization contraction stress may have on bond durability. METHODS: Bonding effectiveness was assessed by micro-tensile bond strength testing (muTBS) and electron microscopy. The muTBS to flat dentin surfaces and in standardized cavities was determined (this after 1 day as well as 1 year water storage). Six adhesives representing all current classes were applied: two etch-and-rinse (OptiBond FL, Kerr; Scotchbond 1, 3M ESPE), two self-etch (Clearfil SE Bond, Kuraray; Adper Prompt, 3M ESPE) and two glass-ionomer (Fuji Bond LC, GC; Reactmer, Shofu) adhesives. RESULTS: The conventional 3-step etch-and-rinse adhesive OptiBond FL bonded most effectively to dentin, and appeared insensitive to polymerization shrinkage stress and water degradation. The 2-step self-etch adhesive Clearfil SE Bond most closely approached this superior bonding effectiveness and only slightly lost bond strength after 1-year water exposure. The 2-step etch-and-rinse adhesive Scotchbond 1 and the 'strong' 1-step self-etch adhesive Adper Prompt appeared very sensitive to cavity configuration and water-aging effects. The 2-step resin-modified glass-ionomer adhesive Fuji Bond LC only suffered from shrinkage stress, but not from 1-year water-exposure. Remarkable also is the apparent repairability of the 'mild' 1-step glass-ionomer adhesive Reactmer when stored for 1 year in water, in spite of the very low 1-day muTBS. SIGNIFICANCE: Simplified bonding procedures do not necessarily imply improved bonding performance, especially in the long term.     

Effect of water storage on the bonding effectiveness of 6 adhesives to Class I cavity dentin

Adhesive-dentin interfaces degrade with time. This study determined the effect water storage may have on the bonding effectiveness of adhesives to occlusal Class I cavity-bottom dentin. Six adhesives, all representing contemporary classes of adhesives, were applied: a 3-step (OptiBond FL, Kerr) and 2-step (Scotchbond 1*, 3M ESPE) etch-and-rinse adhesive, a 2-step (Clearfil SE, Kuraray) and 1-step (Adper prompt, 3M ESPE) self-etch adhesive and a 2-step (FujiBond LC, GC) and 1-step (Reactmer, Shofu) resin-modified glass-ionomer adhesive. Bonding effectiveness was assessed by microtensile bond strength testing (MTBS) and electron microscopy (Feg-SEM and TEM). The MTBS was determined after 1 day and 1 year water storage of the entire restored cavity (indirect exposure of the adhesive-dentin interface to water) and prepared microTBS-beams (direct exposure of the adhesive-dentin interface to water). The hypotheses tested were: (1) resin-dentin bonds formed at the bottom of Class I cavities resist 1-year water storage and (2) an adjacent composite-enamel bond protects the composite-dentin bond against degradation. Non-parametric Kruskal-Wallis analysis statistically analyzed the microTBSs. The first hypothesis was rejected, as only the microTBS of OptiBond FL and Clearfil SE did not significantly decrease after 1-year direct and/or indirect water storage. The second hypothesis was corroborated, as the bonding effectiveness of most simplified adhesives (Scotchbond 1, Adper Prompt, FujiBond LC and Reactmer) approached 0 (because of the frequent pre-testing failures) after 1-year direct water exposure. The second hypothesis concluded that the 3-step etch-and-rinse adhesive must still be regarded the "gold standard." Though microTBS decreased significantly, Clearfil SE, as a 2-step self-etch adhesive, was the only simplified adhesive to perform reliably after 1-year direct water exposure.     

Incompatibility of self-etch adhesives with chemical/dual-cured composites: two-step vs one-step systems

This study tested the null hypothesis that there no difference between two-step and one-step self-etch adhesives in their compatibility with these composites. The microtensile bond strengths (microTBS) of two two-step systems (Clearfil SE Bond, Kuraray and Tyrian SPE/One-Step Plus, BISCO) were compared with two one-step systems (Xeno III, Dentsply DeTrey and Brush&Bond, Parkell) for their coupling to a dual-cured composite. Silver tracer penetration of the four adhesives bonded to a light-cured or a chemical-cured composite was examined using TEM. Significant differences in microTBSs between composite curing modes were seen only in the one-step adhesives. For one-step self-etch adhesives bonded to the chemical-cured composite, TEM revealed signs of frank composite uncoupling along the adhesive-composite interface, which may be attributed to the adverse chemical interaction between the acidic adhesive and the composite. In addition, "water trees" that represent channels of increased permeability with the polymerized adhesive layer were also observed in the one-step adhesives. Both features were absent along the resin-dentin interfaces when chemical-cured composites were coupled to the two-step self-etch adhesives.