Impact of adhesive application to wet and dry dentin on long-term resin-dentin bond strengths

Clinical performance of posterior restorations using a universal adhesive over moist and dry dentin: A 36-month double-blind split-mouth randomized clinical trial

OBJECTIVES

To evaluate the influence of dentin moisture on the clinical behavior of a universal adhesive on posterior teeth after 36 months of follow-up.

METHODS

Forty-five patients participated in this study. Following a split-mouth design, three operators placed 90 Class I/Class II restorations over moist dentin (MD) or dry (DD) (n = 45) with resin composite (Filtek Bulk Fill) and a universal adhesive used in the etch-and-rinse mode (Single Bond Universal). Each restoration was evaluated according to the FDI and USPHS criteria (postoperative sensitivity, fracture and retention, marginal staining, marginal adaptation, and recurrence of caries) at baseline and after 6-, 12-, and 36 months. For statistical analysis, Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used.

RESULTS

No significant difference between groups was observed in each FDI criterion after 36 months of clinical evaluation (p > 0.05). The retention rates (confidence interval 95 %) were 97.37 % (86.5 - 99.5) for both MD and DD without significant difference between them (p > 0.05). Eight restorations (MD = 4; DD = 4) showed minimal marginal staining defects (p > 0.05). Two restorations were lost (MD = 1; DD = 1). Fifteen restorations (MD = 8; DD = 7) presented minor marginal discrepancies according to the FDI criteria (p > 0.05).

CONCLUSION

The clinical performance of the universal adhesive when applied in etch-and-rinse mode was not influenced by dentin moisture in posterior bulk-fill composite restorations.

CLINICAL SIGNIFICANCE

The level of dentin moisture appears not to influence the clinical efficacy of a universal adhesive when applied using the etch-and-rinse technique in posterior composite resin restorations.

Clinical evaluation of posterior restorations over wet and dry dentin using an etch-and-rinse adhesive: A 36-month randomized clinical trial

OBJECTIVES

To evaluate the clinical performance of posterior restorations over wet and dry dentin with an etch-and-rinse adhesive after 36 months of clinical service.

METHODS

Forty-five participants were recruited, each one had at least two posterior teeth that needed restoration. Ninety restorations were placed on Class I or Class II cavities. For the restoration protocol, a simplified etch-and-rinse adhesive (Adper Single Bond 2) was applied over wet (WD) or dry dentin (DD) and later restored with a bulk-fill composite (Filtek Bulk Fill) under rubber dam isolation. Each restoration was evaluated using the World Dental Federation (FDI) criteria after 6, 12, and 36 months of clinical service, regarding the following principal restoration characteristics: postoperative sensitivity, marginal discoloration, marginal adaptation, fracture of material and retention, and recurrence of caries. Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used for statistical analysis.

RESULTS

After 36 months of clinical evaluation, no significant difference between groups was observed in each FDI criterion (p > 0.05). Twenty restorations (WD=10, DD=10) showed minor marginal staining, and twenty-two restorations (WD=11, DD=11) presented small marginal adaptation defects (p > 0.05). Four restorations were lost (WD = 2, DD = 2) and the fracture rates (95% confidence interval) were 94.9% for each one, without significant difference between wet and dry dentin (p > 0.05).

SIGNIFICANCE

The degree of dentin moisture does not seem to affect the clinical performance of a simplified etch-and-rinse adhesive in posterior restorations when the adhesive is applied vigorously over the dentine surface.

Clinical performance of non-carious cervical lesions restored with using self-etch mode of adhesives according to the FDI criteria

AIM

The purpose of this study was to evaluate the 18-month retrospective study of self-etch adhesive (Prime&Bond One Select) and self-etch mode of universal adhesives (Single Bond Universal, Gluma Bond Universal) applied to non-carious cervical lesions according to the World Dental Federation criteria.

MATERIALS AND METHODS

Thirty patients without any systemic disease, good oral hygiene, having at least 20 teeth and six non-carious cervical lesions treated using a self-etch mode of adhesives operated between January and March 2017. Accordingly, 335 restorations were evaluated according to the World Dental Federation criteria at 3, 6, 12 and 18 months. Pillai's Trace test was used to determine the interaction of criteria with time and adhesive systems. IBM SPSS Statistics 21.0 program was used in the analysis. Value of P < 0.05 was accepted as a criterion for statistical significance.

RESULTS

At the end of 18 months, participation was 100%. There was a statistically significant difference P < 0.05 between Prime&Bond One Select and Single Bond Universal, Prime&Bond One Select and Gluma Bond Universal in the 18-month period. In terms of marginal staining, fracture of material and retention, recurrence of caries, erosion and abfraction, tooth integrity criteria at the end of the 18 months, Prime&Bond One Select performed clinically very good, Single Bond Universal and Gluma Bond Universal performed clinically good according to World Dental Federation criteria. Marginal adaptation criteria, Prime&Bond One Select, Single Bond Universal and Gluma Bond Universal performed clinically good. Retention loss rate was found to be the lowest in Prime&Bond One Select and the highest in Gluma Bond Universal.

CONCLUSION

Accordingly, 18-month evaluation of all adhesives used in the study showed clinically acceptable results in all of the World Dental Federation criteria.

Etch-and-rinse versus self-etch strategy of a universal adhesive in different application methods at the bonding interface of fiber post cementation

OBJECTIVE

To evaluate the effect of etch-and-rinse (ER) versus self-etch (SE) strategies of a universal adhesive applied with a manual brush (MB) or rotary brush (RB) on the bonding interface of fiber post cementation.

METHODS

Forty bovine incisor roots were prepared and divided into four groups according to the methods of application and strategy of universal adhesive use (MB-ER, RB-ER, MB-SE and RB-SE). After 6 months, specimens from different thirds of the post space were evaluated of push-out strength, analysis of adhesive failure patterns, and extent of tags.

RESULTS

The RB-ER and RB-SE groups showed the highest bond strength values in the cervical and middle thirds of the post space. Cohesive adhesive failure had the highest incidence in the different thirds of the post space in the ER strategy, regardless of the adhesive application method. The RB-ER group showed the highest tag extensions.

CONCLUSIONS

The protocols of universal adhesive application with RB provided the greater bond strength, but only the ER strategy favored the formation of a greater extension of tags at the adhesive interface.

CLINICAL SIGNIFICANCE

The application of universal adhesive with RB into the post space increases the strength of the post-cemented fiber bond.

Concentration effect of DMSO-dry bonding on the stability of etch-and-rinse bonds

OBJECTIVES

To examine whether lower dimethyl sulfoxide (DMSO) concentrations would affect long-term bond stability of simplified or multistep water-based adhesives to dry-etched dentin.

METHODS

H3PO4-etched mid-coronal dentin surfaces from human molars were randomly blot- or air-dried for 30 s and pretreated or not with 5 or 50 % (v/v) ethanolic DMSO solutions. Untreated samples served as control. Samples were bonded with a two-step or a three-step etch-and-rinse adhesive. Restored crown segments (n = 5/group) were stored in distilled water for 24 h and sectioned for microtensile bond strength testing. Resin-dentin beams (0.8 mm2) were tested under tension until fracture (0.5 mm/min) after 24 h and one year of storage in artificial saliva at 37 °C. Nanoleakage evaluation and hybrid layer characterization were performed by SEM. Bond strength data was examined by three-way ANOVA followed by the Tukey test (α = 0.05).

RESULTS

Dry bonding produced significantly lower bond strengths than conventional wet bonding for both water-based adhesive systems (p < 0.05). DMSO-dry bonding restored bond strengths and reduced nanoleakage levels, regardless of adhesive type or DMSO concentration (p < 0.05). Bond strengths of DMSO-dry bonded samples were not significantly affected by long-term ageing regardless of adhesive type or DMSO concentration (p < 0.05).

SIGNIFICANCE

Although bonding methacrylate-based resins to etched dentin is normally performed under wet conditions, hybridization of air-dried collagen can outperform conventional wet bonding by employing water-free DMSO solutions with concentrations as low as 5 %. Reduced moisture-related technique sensitivity, higher bonding performance and improved hybrid layer stability may contribute to extend the service life of resin-dentin bonding.

Effectiveness of Different Application Modalities on the Bond Performance of Four Polymeric Adhesive Systems to Dentin

One of the major goals of adhesive dentistry is to improve the interaction of the already-existing adhesives with different substrates by using different application techniques. Thus, the objective of the present in vitro study was to assess the bond performance of four adhesive systems, Prime&Bond Universal (PBU), Clearfil SE Bond (CSE), OptiBond Universal (OBU), and OptiBond FL (OBFL), to dentin using various application modes: passive application (PA), active application (AA), Compo-Vibes modified application (CVM), and Compo-Vibes application (CV). Eighty extracted human molars were allocated into four groups based on the application modalities tested. The micro-tensile bond strength as well as fracture mode were tested in accordance with ISO/TS 11.405 after 24 h and 6 months of aging. Adhesive contact angle (CA) and scanning electron microscope analysis were also performed (n = 3). Statistical tests were performed with α = 0.05. After 24 h, a significant difference with a higher bond strength value was found for PBU in the AA modality and for CSE in the CVM modality (p < 0.05). However, no significant difference was shown between the techniques used among the other adhesives (OBFL and OBU). Moreover, at 24 h, only the PA demonstrated significant differences between the tested materials (p < 0.05). After 6 months, CSE, PBU, and OBU demonstrated significant differences between the techniques (p < 0.05), with a higher bond strength for CSE in AA and CVM modalities, for PBU in AA modality, and for OBU in AA and PA modalities. No significant differences were found between the techniques used among the OBFL (p > 0.05). In addition, only the CVM technique demonstrated significant differences between the tested materials after 6 months. CV and CVM showed a decreased value after aging for CSE and PBU, respectively. However, all the modalities decreased for OBU and OBFL after aging. All the adhesives showed marked resin infiltration into dentinal tubules in AA among all the modalities tested. Both universal adhesive systems (OBU and PBU) demonstrated statistically lower CA when compared to the other systems (CSE and OBFL) (p < 0.05) when applied in the PA mode. Concerning the AA mode, only CSE and OBFL were tested. The AA demonstrated lower CA values compared to the same adhesives in PA (p < 0.05). It could be concluded that the bond strength could be influenced by both materials and application techniques. It seems that the AA technique could be recommended as a gold standard for the application of an adhesive system to dentin. Plus, the CV and CVM modalities after 6 months of aging were considered stable for PBU and CSE, respectively. Consequently, the performance of these adhesive systems might vary when applied to other modalities. Future studies are needed to test this hypothesis.

The Use of Warm Air for Solvent Evaporation in Adhesive Dentistry: A Meta-Analysis of In Vitro Studies

Any excess solvent from dental adhesive systems must be eliminated prior to material photopolymerization. For this purpose, numerous approaches have been proposed, including the use of a warm air stream. This study aimed to investigate the effect of different temperatures of warm air blowing used for solvent evaporation on the bond strength of resin-based materials to dental and nondental substrates. Two different reviewers screened the literature in diverse electronic databases. In vitro studies recording the effect of warm air blowing to evaporate solvents of adhesive systems on the bond strength of resin-based materials to direct and indirect substrates were included. A total of 6626 articles were retrieved from all databases. From this, 28 articles were included in the qualitative analysis, and 27 remained for the quantitative analysis. The results of the meta-analysis for etch-and-rinse adhesives revealed that the use of warm air for solvent evaporation was statistically significantly higher (p = 0.005). For self-etch adhesives and silane-based materials, this effect was observed too (p < 0.001). The use of a warm air stream for solvent evaporation enhanced the bonding performance of alcohol-/water-based adhesive systems for dentin. This effect seems to be similar when a silane coupling agent is submitted to a heat treatment before the cementation of a glass-based ceramic.

Some Myths in Dentin Bonding: An Evidence-Based Perspective

Laboratory investigations are essential models responsible for science development. However, laboratory discoveries must be confirmed in a clinical environment where many known and unknown variables and complex mechanisms are involved. Using conclusions from laboratory studies to make clinical recommendations can lead to widespread "unreliable truths" or so-called myths in any field of knowledge. These myths may increase the costs (financial and time) or even cause harm (side effects) that would be unnecessary, given that the current protocol or conduct was previously evaluated in a more complex and complete clinical setting. This article will discuss certain myths in dentin bonding that may influence clinical decision-making, bringing some principles of evidence-based practice to allow a more critical evaluation of the literature findings.

A randomized clinical study of the performance of self-etching adhesives containing HEMA and 10-MDP on non-carious cervical lesions: A 2-year follow-up study

OBJECTIVE

To evaluate the association of HEMA and 10-MDP in the clinical performance of self-etching adhesives in the restoration of NCCLs during 2-years.

MATERIALS AND METHODS

60 restorations were performed in 17 volunteers and randomized into three groups: G1 (n = 20) - Prime and Bond Universal (10-MDP); G2 (n = 20) - Optibond All-in-One (HEMA); and G3 (n = 20) - Clearfil SE (10-MDP and HEMA). No cavity preparation was performed. After 2 years, the restorations were evaluated using the modified USPHS criteria for retention, marginal adaptation/ staining, postoperative sensitivity and secondary caries. The results were analyzed using Fisher's exact test and Kruskal-Wallis test.

RESULTS

All groups showed 100% retention rate, except G1, who lost two restorations (p > 0.05). Regarding marginal adaptation, G1 showed greater deficiency, as only eight restorations (40%) remained intact (p < 0.05). Regarding marginal staining, G1 and G2 showed higher rate, as only 12 restorations (65%) in each one were free of staining (p < 0.05). All groups showed similar results for postoperative sensitivity and secondary caries (p > 0.05).

CONCLUSION

The association of HEMA and 10-MDP monomers in the self-etching adhesives did not influence the clinical performance of the NCCL restorations with respect to retention, postoperative sensitivity, and incidence of secondary caries. However, positively influenced the marginal adaptation and marginal staining at the 2-year follow-up.

CLINICAL SIGNIFICANCE

The association of HEMA and 10-MDP monomers in the self-etching adhesives positively influence the clinical performance of the NCCL restorations with respect to marginal adaptation and marginal staining.

Noncarious cervical lesions: Morphology and progression, prevalence, etiology, pathophysiology, and clinical guidelines for restoration

PURPOSE

To synthesize the literature regarding noncarious cervical lesions (NCCLs) and propose clinical guidelines when lesion restoration is indicated.

MATERIAL AND METHODS

A PubMed search was performed related to NCCL morphology, progression, prevalence, etiology, pathophysiology, and restoration.

RESULTS

NCCLs form as either rounded (saucerlike) depressions with smooth, featureless surfaces that progress mainly in height or as V-shaped indentations that increase in both height and depth. Prevalence ranges from less than 10% to over 90% and increases with age. Common locations are the facial surfaces of maxillary premolars. They have a multifactorial etiology due to personal habits such as excessive horizontal toothbrushing and consumption of acidic foods and drinks. Occlusal factors have been identified as contributing to the prevalence of NCCLs in some studies, whereas other studies indicate there is no relationship. The concept of abfraction has been proposed whereby mechanical stress from occlusal loading plays a role in the development and progression of NCCLs with publications supporting the concept and others indicating it lacks the required clinical documentation. Regardless of the development mechanism, demineralization occurs and they are one of the most common demineralization diseases in the body. Treatment should be managed conservatively through preventive intervention with restorative treatment delayed until it becomes necessary due to factors such as lesion progression, impact on patient's quality of life, sensitivity, poor esthetics, and food collection may necessitate restoration. Composite resins are commonly used to restore NCCLs although other materials such as glass ionomer and resin-modified glass ionomer are also used. Sclerotic dentin does not etch like normal dentin and therefore it has been recommended to texture the dentin surface with a fine rotary diamond instrument to improve restoration retention. Some clinicians use mechanical retention to increase retention. Beveling of enamel is used to increase the bonding area and retention as well as enhance the esthetic result by gradually creating a color change between the restoration and tooth. Both multistep and single-step adhesives have been used. Dentin etching should be increased to 30 seconds due to the sclerotic dentin with the adhesive agent applied using a light scrubbing motion for 20 seconds but without excessive force that induces substantial bending of a disposable applicator. Both flowable and sculptable composite resins have been successfully used with some clinicians applying and polymerizing a layer of flowable composite resin and then adding an external layer of sculptable composite resin to provide enhanced resistance to wear. When caries is present, silver diamine fluoride has been used to arrest the caries rather than restore the lesion.

CONCLUSIONS

Noncarious cervical lesions (NCCLs) form as smooth saucerlike depressions or as V-shaped notches. Prevalence values as high as 90% and as low as 10% have been reported due to habits such as excessive toothbrushing and an acidic diet. Occlusal factors have been proposed as contributing to their presence but it remains controversial. Publications have both supported and challenged the concept of abfraction. They are one of the most common demineralization diseases in the body. Conservative treatment through prevention is recommended with restorative treatment delayed as long as possible. When treatment is needed, composite resins are commonly used with proposed restorative guidelines including texturing the sclerotic dentin, beveling the enamel, potential use of mechanical retention, 30 seconds of acid etching, and use of either multistep or single-step adhesives in conjunction with a light scrubbing motion for 20 seconds without excessive force placed on disposable applicators.

Effect of Different Application Modalities on the Bonding Performance of Adhesive Systems to Dentin: A Systematic Review and Meta-Analysis

Diverse types of dental adhesives exhibit different cytotoxic outcomes on cells in vitro. Currently, no standard adhesive application technique has so far been decisive for clinicians for better durability of resin-dentin bonds of adhesive systems. The purpose of this study was to systematically review the literature to evaluate the bonding performance of adhesive systems to dentin by using different application modalities. The systematic research strategy was conducted by two reviewers among multiple databases: PubMed, Scopus, Web of Science, Embase, and Scielo. In vitro studies reporting the effects of additional steps for the application of adhesive systems on the bond strength to dentin were selected. Meta-analysis was performed using Review Manager Software version 5.3.5 using the random effects model. The methodological quality of each in vitro study was assessed according to the parameters of a previous systematic review. The electronic research through different databases generated a total of 8318 references. After the examination of titles and abstracts, a total of 106 potentially relevant studies accessed the full-text evaluation phase. After full-text examination, 78 publications were included for the qualitative analysis, and 68 studies were included in the meta-analysis. Regarding the etch-and-rinse adhesive systems, the application modalities that improved the overall bond strength were the application of a hydrophobic resin layer (p = 0.005), an extended application time (p < 0.001), an application assisted by an electric current (p < 0.001), a double-layer application (p = 0.05), the agitation technique (p = 0.02), and the active application of the adhesive (p < 0.001). For self-etch adhesive systems, the techniques that improved the overall bond strength were the application of a hydrophobic resin layer (p < 0.001), an extended application time (p = 0.001), an application assisted by an electric current (p < 0.001), a double-layer application (p < 0.001), the agitation technique (p = 0.01), and the active application of the adhesive (p < 0.001). The in vitro evidence suggests that the application of adhesive systems using alternative techniques or additional strategies may be beneficial for improving their bond strength to dentin. The application modalities that favored the overall bond strength to dentin were an extended application time, a double-layer application, an application assisted by an electric current, the active application of the adhesive, and the application of a hydrophobic resin layer. Worth mentioning is that some techniques are intended to increase the degree of the conversion of the materials, and therefore, improvements in the biocompatibility of the materials can be expected.

How Water Content Can Influence the Chemomechanical Properties and Physical Degradation under Aging of Experimental Adhesives

Objective

To evaluate the physicochemical (sorption (SOR), solubility (SOL), and degree of conversion (DC)) and mechanical (flexural strength (FS), modulus of elasticity (ME), and compressive strength (CS)) properties of adhesives with different water contents (D₂O).

Materials and Methods

An adhesive was formulated: 55 wt% BisGMA, 45 wt% HEMA, 0.5 wt% camphorquinone, 0.5 wt% EDMAB, and 1.0 wt% DPIHP. D₂O was added into the adhesives (0 wt%, 10 wt%, and 16 wt%). DC was monitored through the FTIR. FS, ME, CS, SOR, and SOL were tested. The adhesive samples were aged in deionized water, ethanol, and acetone. Data were submitted to ANOVA and Tukey's tests (5%).

Results

For DC, the 0 wt% group showed a significant reduction (68.09 ± 0.14_A) compared with the 10 wt% (87.07 ± 0.81_B) and 16 wt% groups (89.87 ± 0.24_B); 10 wt% showed the highest FS (MPa) mean values (141.6 ± 6.71_B) compared with the 0 wt% (109.4 ± 20.5_A) and 16 wt% (107.8 ± 15.8_A). For the CS (MPa) and ME (GPa), the 16 wt% showed the lowest mean values (98.8 ± 18.0_B and 2.2 ± 0.3_B, respectively) compared with the 10 wt% and 0 wt%. For the SOR, 16 wt% of water showed the highest mean values and the ethanol showed the lowest mean values of SOL regardless of water content.

Conclusion

The amount of water content and the types of aging solvents significantly affect the adhesive properties.

Dry bonding to dentin: Broadening the moisture spectrum and increasing wettability of etch-and-rinse adhesives

OBJECTIVE

To determine whether the effect of dentin moisture on the etch-and-rinse bonding may be minimized by dry-bonding protocols utilizing aqueous or ethanolic dimethyl sulfoxide (DMSO) pretreatments.

METHODS

H₃PO₄-etched mid-coronal dentin surfaces from human molars were randomly blot- or air-dried for 30 s and pretreated with DMSO/H₂O or DMSO/EtOH solutions. Untreated samples served as control. Moisture control was performed by either blot- or air-drying. Samples were bonded with a multistep etch-and-rinse adhesive. Restored crown segments (n = 8/group) were stored in distilled water for 24 h and sectioned for microtensile bond strength testing. Resin-dentin beams (0.8 mm²) were tested under tension until fracture (0.5 mm/min) after 24 h and two years of storage in artificial saliva at 37 °C. SEM nanoleakage evaluation was performed on aged samples. Collagen wettability was also measured by sessile drops of the hydrophilic and hydrophobic bonding resins (n = 8/group). Data were examined by factorial ANOVA followed by the Tukey test (α = 0.05).

RESULTS

Dry bonding to untreated collagen produced inferior immediate and long-term bond strengths than wet bonding (p < 0.05). Regardless of initial hydration and moisture control, DMSO-dry bonding produced initially higher and stable bond strengths after aging (p < 0.05). DMSO-pretreated groups presented improved collagen wettability with lower silver uptake (p < 0.05).

SIGNIFICANCE

Despite the common belief that etch-and-rinse adhesives must be applied onto moist collagen, DMSO-dry bonding protocols not only improved bonding performance and hybrid layer integrity, but also brought more versatility to collagen hybridization by reducing overdrying-related issues.

Bond Strength of Universal Adhesives to Dentin: A Systematic Review and Meta-Analysis

Currently, the availability of a wide variety of universal adhesives makes it difficult for clinicians to choose the correct system for specific bonding situations to dentin substrate. This study aimed to determine whether there are any alternative techniques or additional strategies available to enhance the bond strength of universal adhesives to dentin through a systematic review and meta-analysis. Two reviewers executed a literature search up to September 2020 in four electronic databases: PubMed, ISI Web of Science, Scopus, and EMBASE. Only in vitro studies that reported the dentin bond strength of universal adhesives using additional strategies were included. An analysis was carried out using Review Manager Software version 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). The methodological quality of each in vitro study was assessed according to the parameters of a previous systematic. A total of 5671 potentially relevant studies were identified. After title and abstract examination, 74 studies remained in systematic review. From these, a total of 61 studies were included in the meta-analysis. The bond strength of universal adhesives to dentin was improved by the use of one of the following techniques: Previous application of matrix metalloproteinases (MMP) inhibitors (p < 0.001), prolonged application time (p = 0.007), scrubbing technique (p < 0.001), selective dentin etching (p < 0.001), non-atmospheric plasma (p = 0.01), ethanol-wet bonding (p < 0.01), prolonged blowing time (p = 0.02), multiple layer application (p = 0.005), prolonged curing time (p = 0.006), and hydrophobic layer coating (p < 0.001). On the other hand, the use of a shortened application time (p = 0.006), and dentin desensitizers (p = 0.01) impaired the bond strength of universal adhesives to dentin. Most of the analyses performed showed a high heterogenicity. The in vitro evidence suggests that the application of universal adhesives using some alternative techniques or additional strategies may be beneficial for improving their bonding performance to dentin. This research received no external funding. Considering that this systematic review was carried out only with in vitro studies, registration was not performed.

Effect of Non-Thermal Atmospheric Plasma on Micro-Tensile Bond Strength at Adhesive/Dentin Interface: A Systematic Review

Objective: The objective of this review was to evaluate the effect of non-thermal atmospheric plasma (NTAP) on adhesives resin–dentin micro-tensile bond strength (μTBS) in previously published studies. Methods: Electronic search was conducted using the Medline, Cochrane library, and Scopus databases. The included studies were laboratory studies that investigated the effect of NTAP on adhesives μTBS to coronal dentin. Studies that evaluated the effect of NTAP on bond strength to indirect substrates, enamel or root dentin, were excluded. The methodological quality of included studies was assessed. Results: Thirteen studies were included in this systematic review. All the included studies were considered to have a medium risk of bias. NTAP significantly improved μTBS at 24 h or after short-term aging in five studies (38.5%) and both immediate and after long-term aging in 5 studies (38.5%). In two studies (15.4%), NTAP resulted in a short-term material-dependent effect that was not stable after long-term aging. Interestingly, in one study (7.7%), NTAP had a positive effect only in the etch-and-rinse (ER) mode after long-term aging. Conclusion: Within the limitations of this systematic review, NTAP application could enhance resin–dentin μTBS of ER adhesives or universal adhesives (UAs) applied in the ER mode. In the ER mode, the rewetting step after NTAP seems to be unnecessary. Because of the limited information currently available in the literature, further studies are required to evaluate the effect of the NTAP application on self-etch (SE) adhesives or UAs applied in the SE mode.

Effect of ultrasonic activation of the adhesive system on dentin tubule penetration and the pushout bond strength of fiber posts

STATEMENT OF PROBLEM

Whether ultrasonic activation of the adhesive system improves dentin tubule penetration and the bond strength of fiber posts to root dentin is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of ultrasonic activation of 2 adhesive systems (etch-and-rinse and self-etch) and 1 glass ionomer cement on the dentin tubule penetration and pushout bond strength of fiber posts to root dentin.

MATERIAL AND METHODS

Sixty maxillary central incisors were endodontically treated and divided into 6 groups (n=10) as per the post cementation strategy: etch-and-rinse, etch-and-rinse and ultrasonic, self-etch, self-etch and ultrasonic, glass ionomer cement, and glass ionomer cement and ultrasonic. The primers, the adhesives, and the glass ionomer cement were activated for 20 seconds each, and the fiber posts were cemented with a resin cement. Dentin tubule penetration was evaluated by confocal laser scanning microscopy and the pushout bond strength measured at 3 post locations: cervical, middle, and apical. The failure patterns were also described after pushout testing.

RESULTS

Self-etch and ultrasonic showed higher dentin tubule penetration than the other cementation strategies (P<.05) and improved the bond strength values (P<.05), which were higher than etch-and-rinse and ultrasonic and glass ionomer cement and ultrasonic (P<.05). Adhesive failures at the cement and dentin interface were predominant in the etch-and-rinse, self-etch, and self-etch and ultrasonic groups.

CONCLUSIONS

Ultrasonic activation improved the dentin tubule penetration of a self-etch adhesive system. The bond strength of fiber posts cemented with a self-etch adhesive system and a resin cement was improved after ultrasonic activation.

Current perspectives on dental adhesion: (3) Adhesion to intraradicular dentin: Concepts and applications

Adhesion science is one of the greatest contributions to restorative dentistry. Adhesion not only established the current principles of tissue preservation, but also allowed for the production of more hermetic and long-lasting restorations. Although adhesive strategies are routinely used in most clinical situations, adhesion to root dentin is still a major challenge. The presence of humidity together with less intertubular dentin are factors that limit the adhesive potential of root dentin. This situation is more unfavorable in endodontically treated teeth prepared for prefabricated or custom-made intraradicular posts; these procedures may alter the mechanical properties of teeth by modifying the viable dentin surface for adhesion. Also, contaminants deposited on the dentin surface are difficult to remove through conventional techniques. Moreover, root canal morphology has a very unfavorable C-factor, bringing undesirable effects resulting from polymerization contraction of resin-based materials. However, the differences between coronal and root dentin are not a barrier for dentin adhesion. Standardization of procedures and care during clinical steps are fundamental to the success of adhesion to coronal or intraradicular dentin. Thus, it is essential to know the anatomy of the root structure, the factors that interfere with intraradicular adhesion, as well as the current adhesive materials and techniques.

Adhesive Dentistry: Understanding the Science and Achieving Clinical Success

Successful adhesive dentistry begins with correct placement and polymerization of the bonding agent. Although numerous agents exist, all abide by certain key principles, including the newest group, the universal adhesives. Fundamental steps also exist in the application process that require the operator to understand the chemistry of the adhesive being used. Modalities exist that can help preserve the durability of the bond achieved, thus slowing down the degradation process. However, no material or agent can overcome poor technique. Thus, it is of the utmost importance that the practitioner respects the technique sensitivity of adhesives, and follows the manufacturer's instructions.

A New Dual-cure Universal Simplified Adhesive: 18-month Randomized Multicenter Clinical Trial

CLINICAL RELEVANCE

Non-carious cervical lesion restorations using a dual-cure universal adhesive in self-etch and etch-and-rinse mode showed satisfactory clinical performance after 18 months.

SUMMARY

Objectives: The objective of this multicenter, double-blind, split-mouth randomized clinical trial was to evaluate the clinical performance of a new dual-cure universal adhesive system (Futurabond U, Voco GmBH) when applied using different strategies over a period of 18 months.Methods and Materials: Fifty patients participated in this study. Two hundred non-carious cervical lesions were restored using the adhesive Futurabond U according to four adhesive strategies (n=50 per group): only self-etch (SEE), selective enamel etching + self-etch (SET), etch-and-rinse with dry dentin (ERDry), and etch-and-rinse with wet dentin (ERWet). After the adhesive application, cavities were restored using Admira Fusion composite resin. These restorations were evaluated according to FDI World Dental Federation criteria for the following characteristics: retention/fracture, marginal adaptation, marginal staining, postoperative sensitivity, and caries recurrence.Results: After 18 months, only four patients (12 months: one patient, n=4 restorations; and 18 months: three patients, n=12 restorations) were not evaluated. Fourteen restorations were lost after 18 months of clinical evaluation (four for SEE, three for SET, three for ERDry, and four for ERWet). The retention rates for 18 months (95% confidence interval) were 92% (81%-97%) for SEE, 94% (83%-97%) for SET, 94% (83%-97%) for ERDry, and 92% (81%-97%) for ERWet (p>0.05). Thirty-eight restorations were considered to have minor discrepancies in marginal adaptation at the 18-month recall (13 for SEE, 13 for SET, six for ERDry, and six for ERWet; p>0.05). Fourteen restorations were detected as a minor marginal discoloration at the 18-month recall (six for SEE, six for SET, one for ERDry, and one for ERWet; p>0.05). However, all were considered clinically acceptable. No restorations showed postoperative sensitivity or caries recurrence at the time.Conclusion: The clinical performance of the Futurabond U did not depend on the bonding strategy used, and it was considered reliable after 18 months of clinical evaluation, although more marginal discrepancy was observed in the self-etch group.

Microtensile Bond Strength of Composite Resin Following the Use of Bromelain and Papain as Deproteinizing Agents on Etched Dentin: An In Vitro Study

Aim and objectives

The aim of this study was to evaluate and compare the deproteinizing effect of sodium hypochlorite, bromelain, and papain on microtensile bond strength of composite resin to etched dentin.

Materials and methods

Eighty freshly extracted permanent molars were wet grounded into a flat surface using a diamond disk to expose the superficial dentinal surface. Teeth were etched with 37% phosphoric acid for 15 seconds and rinsed with water and blot dried. Teeth were divided into four groups (n = 20) based on the method of dentin deproteinization. Group I: only etching; group II: deproteinized with 5.25% sodium hypochlorite for 1 minute; group III: deproteinized with 8% bromelain enzyme for 1 minute; and group IV: deproteinized with 8% papain enzyme for 1 minute. All the samples were washed off with distilled water to remove deproteinizing agents. Sample surfaces were blot dried and bonding of the dentin surface was performed and restored with light cure bulk fill composite. Samples were stored in distilled water (37°C/24 hours) and thermocycled. Then, the teeth were longitudinally sectioned and individually fixed to a sectioning block using acrylic resin. The block was mounted on hard tissue microtome and sectioned to get one to three slabs of 1 mm thick sections. The beam was then attached to a custom-made jig using screws subjected to the Instron universal testing machine. A tensile load was applied at a crosshead speed of 0.5 mm/minute until the beam fractured.

Results

Higher mean bond strength was recorded in group IV followed by group III, group II, and group I, respectively. Group III presented a statistically significant highest mean score compared to other study groups with group I and group II (p < 0.001), followed by group IV having significantly higher mean score compared to group I and group II (p < 0.001) and finally a significant difference was observed between group II and group I (p < 0.001). However, the mean microtensile bond strength score did not differ significantly between group III and group IV (p = 0.20).

Conclusion

Within the limitations of this present in vitro study, the following conclusions were drawn. The microtensile bond strength of dentine tested in various deproteinizing agents is as follows: 8% bromelain > 8% papain > 5.25% NaOCl > control group. Naturally occurring deproteinizing agents, such as bromelain and papain, used in this study have resulted in greater bond strength values when compared to that of traditionally used chemical agent such as NaOCl.

How to cite this article

Khatib MS, Devarasanahalli SV, Aswathanarayana RM, et al. Microtensile Bond Strength of Composite Resin Following the Use of Bromelain and Papain as Deproteinizing Agents on Etched Dentin: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(1):43–47.

The inhibitory effect of carboxyl-terminated polyamidoamine dendrimers on dentine host-derived matrix metalloproteinases in vitro in an etch-and-rinse adhesive system

The biomimetic remineralization of collagen fibrils has increased interest in restoring the demineralized dentine generated by dental caries. Carboxyl-terminated polyamidoamine dendrimers (PAMAM-COOH), hyperbranched polymeric macromolecules, can act as non-collagenous proteins to induce biomimetic remineralization on a dentine organic matrix. However, in vivo remineralization is an extremely time-consuming process; before complete remineralization, demineralized dentine collagen fibrils are susceptible to degradation by host-derived matrix metalloproteinases (MMPs). Therefore, we examined the effect of fourth-generation PAMAM-COOH (G4-PAMAM-COOH) on the collagenolytic activities of endogenous MMPs, the interaction between G4-PAMAM-COOH and demineralized dentine collagen and the influence of G4-PAMAM-COOH pre-treatment on resin-dentine bonding. G4-PAMAN-COOH not only inhibited exogenous soluble rhMMP9 but also hampered the proteolytic activities of dentine collagen-bound MMPs. Cooperated with the results of G4-PAMAM-COOH absorption and desorption, FTIR spectroscopy provided evidence for the exclusive electrostatic interaction rather than hydrogen or covalent bonding between G4-PAMAM-COOH and dentine collagen. Furthermore, G4-PAMAM-COOH pre-treatment showed no damage to resin-dentine bonding because it did not significantly decrease the elastic modulus of the demineralized dentine, degree of conversion, penetration of the adhesive into the dentinal tubules or ultimate tensile strength. Thus, G4-PAMAM-COOH can effectively inactivate MMPs, retard the enzymolysis of collagen by MMPs and scarcely influence the application of resin-dentine bonding.

The effect of warm air-blowing on the microtensile bond strength of one-step self-etch adhesives to root canal dentin

PURPOSE

The use of warm air-blowing to evaporate solvents of one-step self-etch adhesive systems (1-SEAs) has been reported to be a useful method. The purpose of this study was to evaluate the effect of warm air-blowing on root canal dentin.

METHODS

Four 1-SEAs (Clearfil Bond SE ONE, Unifil Core EM self-etch bond, Estelink, BeautiDualbond EX) were used. Each 1-SEA was applied to root canal dentin according to the manufacturers' instructions. After the adhesives were applied, solvent was evaporated using either normal air (23±1°C) or warm air (80±1°C) for 20s, and resin composite was placed in the post spaces. The air from the dryer, which could be used in normal- or hot-air-mode, was applied at a distance of 5cm above the root canal cavity in the direction of tooth axis. The temperature of the stream of air from the dryer in the hot-air-mode was 80±1°C, and in the normal mode, 23±1°C. After water storage of the specimens for 24h, the μTBS were evaluated at the coronal and apical regions. The μTBSs were statistically analyzed using three-way ANOVA and Student's t-test with Bonferroni correction (α=0.05).

RESULTS

The warm air-blowing significantly increased the μTBS of all 1-SEAs at the apical regions, and also significantly increased the μTBS of two adhesives (Estelink and BeautiDualBond EX) at coronal regions.

CONCLUSIONS

The μTBS of 1-SEAs to root canal dentin was improved by using warm air-blowing.

Bond Strength and Cytotoxicity of a Universal Adhesive According to the Hybridization Strategies to Dentin

Abstract This study evaluated application protocol (etch-and-rinse/ER and self-etching/SE) and dentin wettability (wet and dry) on microtensile bond strength (μTBS) and transdentinal cytotoxicity of ScotchbondTM Universal (SU) adhesive system. The μTBS values and fracture mode were registered 24 h after adhesive system application and resin composite block build-up (n=5). For analysis of transdentinal cytotoxicity, odontoblast-like MDPC-23 cells were seeded on pulpal surface of dentin discs (0.4 mm thick) adapted to artificial pulp chambers (n=8). The adhesive system was applied to occlusal surface, followed by 24-h incubation time. Cell viability (Alamar Blue) and morphology (SEM) were assessed. Adper Single Bond 2 and Clearfil SE Bond were used as positive controls of the ER and SE application protocols, respectively. No treatment was performed on negative control (NC) group. Data were analyzed by ANOVA and Tukey’s tests (α=5%). Higher μTBS values were found for ER mode in comparison with SE protocol (p<0.05). Dentin wettability had no effect on bond strength of SU in both the ER and SE techniques (p>0.05). Most fractures involved hybrid layer and/or adhesive layer. Neither variable prevented the intense toxic effects of adhesive systems on MDPC-23 cultured cells, since intense reduction in cell viability (±88%) and severe alterations in cell morphology were observed for all groups compared to NC, with no differences among them (p>0.05). Therefore, it was concluded that application of SU following the ER protocol had better adhesive performance. However, this adhesive system featured intense transdentinal cytotoxicity to pulp cells, regardless of application protocol and dentin wettability.

Effect of rubbing force magnitude on bond strength of universal adhesives applied in self-etch mode

This study investigated the effect of rubbing force magnitude on dentin bond strengths of multi-mode adhesives applied in self-etch mode. Seventy-two extracted human molar teeth were used. Two different universal adhesives Single Bond Universal (SB) and Clearfil Universal (CL) were applied onto dentin surfaces in three different modes: without rubbing (NR), rubbing with 40 gf (gram-force) (40) or 80 gf (80) load. Teeth were restored with a resin composite. Half of the specimens were subject to thermal aging (10,000 cycles). Microtensile bond strength was measured and data were statistically analyzed with two-way analysis of variance and Tukey's test (α=0.05). Baseline bond strength values for CL adhesive were improved by rubbing (40 and 80 gf) as compared to no rubbing (p<0.05). Rubbing did not significantly improve bond strength values for SB, regardless of aging (p>0.05). Rubbing improves bonding performance of some universal adhesives to dentin when applied in self-etch mode.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey's post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives.

Effect of Different Protocols in Preconditioning With EDTA in Sclerotic Dentin and Enamel Before Universal Adhesives Applied in Self-etch Mode

Objectives:

The aim of this study was to investigate the effect of different protocols of 17% ethylene diamine tetra-acetic acid (EDTA) conditioning on the etching pattern and immediate bond strength of universal adhesives to enamel and sclerotic dentin.

Methods and Materials:

Forty bovine teeth with sclerotic dentin and 20 human third molars were randomly divided into eight groups resulting from the combination of the main factors surface treatment (none, two-minute EDTA conditioning manual application, 30-second EDTA manual application, 30-second EDTA sonic application) and adhesives systems (Scotchbond Universal Adhesive [SBU] and Prime & Bond Elect [PBE]). Resin-dentin and enamel-dentin bond specimens were prepared and tested under the microtensile bond strength (μTBS) and microshear bond strength (μSBS) tests, respectively. The etching pattern produced on the unground enamel and the sclerotic dentin surfaces under the different protocols and adhesive systems was evaluated under scanning electron microscopy.

Results:

For enamel, only the main factor adhesive was significant (p&lt;0.0001), with SBU showing the highest μSBS. In sclerotic dentin, the lowest mean was observed for the group without EDTA application and the highest mean in the group with EDTA application with the sonic device for 30 seconds. Regardless of the EDTA protocol, the highest means of μTBS were observed for SBU (p&lt;0.05).

Conclusions:

EDTA conditioning improves the bonding performance of universal adhesives in the self-etch mode on sclerotic dentin, mainly when applied for 30 seconds with the aid of a sonic device. EDTA pretreatment also improves the retentive etching pattern of enamel, but it does not result in higher enamel bond strength.

Cytotoxicity of Etch-and-Rinse, Self-Etch, and Universal Dental Adhesive Systems in Fibroblast Cell Line 3T3

The aim of this study was to evaluate in fibroblast cultures the direct cytotoxic effects of etch-and-rinse, self-etch, and universal adhesive systems. The sterile glass cover slips (n = 3) were then immersed in culture medium to obtain the eluates for the experimental groups: (1) Adper™ Single Bond 2; (2) Ambar; (3) Adper™ Scotchbond™ Multi-Purpose; (4) Scotchbond™ Universal; (5) Ambar Universal; and (6) OptiBond All-In-One. As a negative control, sterile glass cover slips were immersed in culture medium only. After 24 h, the eluate obtained was applied on fibroblast culture. Cell viability and cell morphology were evaluated by MTT assay and SEM, respectively. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). All adhesive systems except universal reduced cell viability in 3T3 cells to between 26.04% and 56.57%, and Scotchbond Universal and Ambar Universal reduced cell viability to 2.13% and 3.57%, respectively, when compared to the negative control. Cytoplasmic membrane shrinkage and cell-free areas with residual membrane fragments from dead cells were observed. In conclusion, improvements in universal adhesive system formulations and their mechanisms of action are not accompanied by increased toxicity compared with those in other systems, warranting commitment to the use of these dentin-pulp complexes.

Influence of Conditioning Time of Universal Adhesives on Adhesive Properties and Enamel-Etching Pattern

OBJECTIVES

To evaluate the effect of application protocol in resin-enamel microshear bond strength (μSBS), in situ degree of conversion, and etching pattern of three universal adhesive systems.

METHODS AND MATERIALS

Sixty-three extracted third molars were sectioned in four parts (buccal, lingual, and proximals) and divided into nine groups, according to the combination of the main factors-Adhesive (Clearfil Universal, Kuraray Noritake Dental Inc, Tokyo, Japan; Futurabond U, VOCO, Cuxhaven, Germany; and Scotchbond Universal Adhesive, 3M ESPE, St Paul, MN, USA)-and enamel treatment/application time (etch-and-rinse mode [ER], self-etch [SE] application for 20 seconds [SE20], and SE application for 40 seconds [SE40]). Specimens were stored in water (37°C/24 h) and tested at 1.0 mm/min (μSBS). The degree of conversion of the adhesives at the resin-enamel interfaces was evaluated using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a scanning electron microscope. Data were analyzed with two-way analysis of variance and Tukey test (α=0.05).

RESULTS

In general, the application of the universal adhesives in the SE40 produced μSBS and degree of conversion that were higher than in the SE20 (p<0.01) and similar to the ER mode. The deepest enamel-etching pattern was obtained in the ER mode, followed by the SE40.

CONCLUSIONS

The active and prolonged application of universal adhesives in the SE mode may be a viable alternative to increase the degree of conversion, etching pattern, and resin-enamel bond strength.

Comparison of Shear Bond Strength of Universal Adhesives on Etched and Nonetched Enamel

Background

The purpose of this study was to evaluate the effect of surface pretreatment with 37% phosphoric acid on the enamel bond strength of different universal adhesives.

Methods

One hundred and sixty bovine permanent mandibular incisors freshly extracted were used as a substitute for human teeth. The materials tested in this study included 6 universal adhesives, and 2 self-etch adhesives as control. The teeth were assigned into 2 groups: In the first group, etching was performed using 37% phosphoric acid for 30 seconds. In the second group, no pretreatment agent was applied. After adhesive application, a nanohybrid composite resin was inserted into the enamel surface by packing the material into cylindrical-shaped plastic matrices. After storing, the specimens were placed in a universal testing machine. The normality of the data was calculated using the Kolmogorov-Smirnov test. Analysis of variance (ANOVA) was applied to determine whether significant differences in debond strength values existed among the various groups.

Results

Groups with phosphoric acid pretreatment showed significantly higher shear bond strength values than groups with no enamel pretreatment (p<0.001). No significant variation in shear strength values was detected when comparing the different adhesive systems applied onto enamel after orthophosphoric acid application (p>0.05).

Conclusions

All adhesives provide similar bond strength values when enamel pretreatment is applied even if compositions are different. Bond strength values are lower than promised by manufacturers.

Does active application of universal adhesives to enamel in self-etch mode improve their performance?

OBJECTIVES

To evaluate the effect of adhesion strategy on the enamel microshear bond strengths (μSBS), etching pattern, and in situ degree of conversion (DC) of seven universal adhesives.

METHODS

84 extracted third molars were sectioned in four parts (buccal, lingual, proximal) and divided into 21 groups, according to the combination of the main factors adhesive (AdheSE Universal [ADU], All-Bond Universal [ABU], Clearfil Universal [CFU], Futurabond U [FBU], G-Bond Plus [GBP], Prime&Bond Elect (PBE), and Scotchbond Universal Adhesive [SBU]), and adhesion strategy (etch-and-rinse, active self-etch, and passive self-etch). Specimens were stored in water (37°C/24h) and tested at 1.0mm/min (μSBS). Enamel-resin interfaces were evaluated for DC using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a field-emission scanning electron microscope (direct and replica techniques). Data were analyzed with two-way ANOVA and Tukey's test (α=0.05).

RESULTS

Active self-etch application increased μSBS and DC for five out of the seven universal adhesives when compared to passive application (p<0.001). A deeper enamel-etching pattern was observed for all universal adhesives in the etch-and-rinse strategy. A slight improvement in etching ability was observed in active self-etch application compared to that of passive self-etch application. Replicas of GBP and PBE applied in active self-etch mode displayed morphological features compatible with water droplets. The DC of GBP and PBE were not affected by the application/strategy mode.

CONCLUSIONS

In light of the improved performance of universal adhesives when applied actively in SE mode, selective enamel etching with phosphoric acid may not be crucial for their adhesion to enamel.

CLINICAL SIGNIFICANCE

The active application of universal adhesives in self-etch mode may be a practical alternative to enamel etching in specific clinical situations.

Can 1% chlorhexidine diacetate and ethanol stabilize resin-dentin bonds?

OBJECTIVES

To examine the effects of the combined use of chlorhexidine and ethanol on the durability of resin-dentin bonds.

METHODS

Forty-eight flat dentin surfaces were etched (32% phosphoric acid), rinsed (15 s) and kept wet until bonding procedures. Dentin surfaces were blot-dried with absorbent paper and re-wetted with water (water, control), 1% chlorhexidine diacetate in water (CHD/water), 100% ethanol (ethanol), or 1% chlorhexidine diacetate in ethanol (CHD/ethanol) solutions for 30 s. They were then bonded with All Bond 3 (AB3, Bisco) or Excite (EX, Ivoclar-Vivadent) using a smooth, continuous rubbing application (10 s), followed by 15 s gentle air stream to evaporate solvents. The adhesives were light-cured (20 s) and resin composite build-ups constructed for the microtensile method. Bonded beams were obtained and tested after 24-h, 6-months and 15-months of water storage at 37°C. Storage water was changed every month. Effects of treatment and testing periods were analyzed (ANOVA, Holm-Sidak, p<0.05) for each adhesive.

RESULTS

There were no interactions between factors for both etch-and-rinse adhesives. AB3 was significantly affected only by storage (p=0.003). Excite was significantly affected only by treatments (p=0.048). AB3 treated either with ethanol or CHD/ethanol resulted in reduced bond strengths after 15 months. The use of CHD/ethanol resulted in higher bond strengths values for Excite.

CONCLUSIONS

Combined use of ethanol/1% chlorhexidine diacetate did not stabilize bond strengths after 15 months.

Effects of sonic application of adhesive systems on bonding fiber posts to root canals

INTRODUCTION

Luting posts inside the root canal is still a challenge because of the difficulty of bonding adhesive materials in the apical third of roots. This study evaluated the effect of the application mode of 3 simplified etch-and-rinse adhesives on the push-out bond strength (PBS), nanoleakage (NL), and in situ degree of conversion (DC) of fiber posts in the root canal.

METHODS

The roots of human premolars were endodontically prepared and divided into 6 groups according to the combination of the main factors: adhesive (Ambar, FGM, Joinville, SC, Brazil; Adper Single Bond 2, 3MESPE, St Paul, MN; and XP Bond+self-cure activator, DeTrey Dentsply, Konstanz, Germany) and application mode (manual or sonic). The posts were cemented and the PBS tested at 0.5 mm/min. The NL was evaluated by scanning electron microscopy after the immersion of specimens in 50% silver nitrate. Micro-Raman spectroscopy was used to measure the in situ DC. Root third was also considered in the statistical evaluation. Data were analyzed by 3-way repeated measures analysis of variance and Tukey tests (5%).

RESULTS

Under sonic application, the PBS and the in situ DC increased, whereas NL decreased significantly for all groups in the middle and apical thirds (P < .05).

CONCLUSIONS

The application of simplified adhesives by sonic mode in the root canal is a feasible tool to increase the fiber post bond to root canals.

Effect of sonic application mode on the resin-dentin bond strength and nanoleakage of simplified self-etch adhesive

OBJECTIVES

This study aims to evaluate the effect of different application modes on the immediate and 6-month resin-dentin bond strength (μTBS) and nanoleakage in the hybrid and adhesive layers.

MATERIALS AND METHODS

Three 1-step self-etch adhesives (One Coat 7.0 (OC), Clearfil S(3) Bond (CS), and FuturaBond NR (FB)) were applied on a flat superficial dentin surface of 30 human molars under manual mode or sonic vibration at a frequency of 170 Hz (SV). Composite build-ups were constructed incrementally; specimens were sectioned to obtain resin-dentin sticks with cross-sectional area of 0.8 mm(2) and tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6M) of water storage. Two bonded sticks, from each tooth at each storage time, were immersed in a silver nitrate solution, photo-developed, and analyzed under scanning electron microscopy. The amount of nanoleakage was measured using the ImageTool 3.0 software. Data, from each adhesive, were analyzed by two-way ANOVA and Tukey's test (α = 0.05).

RESULTS

OC and CS showed higher μTBS and lower nanoleakage in the IM period when applied with SV groups. For FB, no significant difference was observed between the two modes of application. All materials showed lower nanoleakage in the SV groups. Higher nanoleakage was observed after 6M for OC and FB.

CONCLUSIONS

The sonic application mode at an oscillating frequency of 170 Hz can improve the resin-dentin μTBS, reduce the nanoleakage, and retard the degradation of the resin-dentin μTBS of Clearfil S(3) Bond and One Coat 7.0 adhesives.

CLINICAL SIGNIFICANCE

Sonic application mode at an oscillating frequency of 170 Hz can be helpful and easy to use in dental practice to guaranty long-lasting restorations.

Overview of Clinical Alternatives to Minimize the Degradation of the Resin-dentin Bonds

The incorporation of hydrophilic and acidic resin monomers substantially improved the initial bonding of contemporary etch-and-rinse (ER) and self-etch (SE) adhesives to intrinsically wet dental substrates, providing quite favorable immediate results, regardless of the bonding approach used. However, in the long term, the bonding effectiveness of most simplified ER and SE adhesives drop dramatically. This review examines the fundamental processes that are responsible for the aging mechanisms involved in the degradation of the resin-bonded interfaces and some possible clinical approaches that have been effective in minimizing or even preventing the degradation of the adhesive interfaces produced with simplified adhesives. The incorporation of some of the feasible approaches - described in this review - may improve the quality of the adhesive restorations performed in clinical practice, while manufacturers develop bonding materials that are less susceptible to the aging mechanisms present in the oral environment.

Bond strength of adhesive systems with different solvents to dry and wet dentin

AIM

This study evaluates bond strength between dentin and composite using adhesives with different solvents to dry and wet dentin.

MATERIALS AND METHODS

Ninety bovine incisors were used; the vestibular surfaces were worn by the exposure of an area with a diameter of 4 mm of dentin. The specimens were divided into 6 groups, according to the type of adhesive used and hydratation stals: Group SB-wet: Single Bond 2 in wet dentin, Group SBdry: Single Bond 2 in dry dentin, Group SL-wet: Solobond M in wet dentin, Group SL-dry: Solobond M in dentin dry. Group XPwet: XP Bond in wet dentin, Group XP-dry: XP Bond in dentin dry. They were cut to obtain specimens in the shape of stick with 1 × 1 mm and subjected to microtensile test in universal testing machine with a cross speed of 1mm/min. The data were analyzed with ANOVA and Tukey's tests (5%).

RESULTS

ANOVA showed significant differences for surface treatment and interaction, but no difference was found for adhesive factor. The Tukey's test showed that the samples with wet dentin shown higher values of bond strength.

CONCLUSION

The adhesive did not influence in the bond strength. The groups with wet dentin showed higher values of bond strength than groups with dry dentin.

The role of dentin moisture in the degradation of resin-dentin interfaces under clinical and laboratory conditions

BACKGROUND

The authors conducted a study to evaluate the influence of dentin moisture on the degradation of the resin-dentin interface in primary teeth under clinical and laboratory conditions.

METHODS

The authors prepared 40 Class I restorations (five teeth per group) by using a cylindrical diamond bur, leaving a flat dentin surface on the pulpal floor. They vigorously rubbed two coats of a simplified etch-and-rinse adhesive on either dry or wet demineralized dentin under clinical or laboratory conditions. After performing restorative procedures, the authors extracted teeth prepared under clinical conditions after 20 minutes (immediately) or the teeth exfoliated after six months. The authors also tested the teeth prepared under laboratory conditions immediately or after six months of being stored in water. They sectioned the teeth to obtain resin-dentin bonded specimens for microtensile testing and for silver nitrate uptake (SNU) under scanning electron microscopy. They performed a three-way analysis of variance and Tukey test (α = .05) on the SNU bond strength data.

RESULTS

Statistically higher bond strength values (megapascals [standard deviation]) were observed when bonding was performed under laboratory conditions (clinical = 25.2 [3.6] MPa versus laboratory = 28.5 [4.4] MPa; P < .05). Degradation occurred only in the wet dentin groups under both experimental conditions (immediately = 31.3 [4.5] MPa versus after six months = 21.3 [2.1] MPa; P < .05). SNU occurred in all groups and was statistically higher after six months of clinical function or water storage (immediately = 13.9 [4.9 SD] percent versus after six months = 34.1 [4.5 SD] percent; P < .05).

CONCLUSIONS

The bonding of adhesives to dry demineralized dentin produces adhesive interfaces that are more resistant to degradation regardless of the bonding condition.

CLINICAL IMPLICATIONS

Resin-dentin bond strengths produced under laboratory conditions in primary teeth may be higher than those obtained under clinical circumstances, although both conditions (clinical and laboratory) seemed to yield similar results. Bonding to dry demineralized primary tooth dentin produced resin-dentin interfaces that were more resistant to degradation.

Effect of application mode on interfacial morphology and chemistry between dentine and self-etch adhesives

OBJECTIVE

To investigate the influence of application mode on the interfacial morphology and chemistry between dentine and self-etch adhesives with different aggressiveness.

METHODS

The occlusal one-third of the crown was removed from un-erupted human third molars, followed by abrading with 600 grit SiC under water. Rectangular dentine slabs were prepared by sectioning the tooth specimens perpendicular to the abraded surfaces. The obtained dentine slabs were treated with one of the two one-step self-etch adhesives: Adper Easy Bond (AEB, pH∼2.5) and Adper Prompt L-Pop (APLP, pH∼0.8) with (15s, active application) or without (15s, inactive application) agitation. The dentine slabs were fractured and the exposed adhesive/dentine (A/D) interfaces were examined with micro-Raman spectroscopy and scanning electron microscopy (SEM).

RESULTS

The interfacial morphology, degree of dentine demineralization (DD) and degree of conversion (DC) of the strong self-etch adhesive APLP showed more significant dependence on the application mode than the mild AEB. APLP exhibited inferior bonding at the A/D interface if applied without agitation, evidenced by debonding from the dentine substrate. The DDs and DCs of the APLP with agitation were higher than those of without agitation in the interface, in contrast to the comparable DD and DC values of two AEB specimen groups with different application modes. Raman spectral analysis revealed the important role of chemical interaction between acid monomers of self-etch adhesives and dentine in the above observations.

CONCLUSION

The chemical interaction with dentine is especially important for improving the DC of the strong self-etching adhesive at the A/D interface. Agitation could benefit polymerization efficacy of the strong self-etch adhesive through enhancing the chemical interaction with tooth substrate.

Layering composites for ultimate aesthetics in direct restorations

A number of modern materials are available which allow placement of highly aesthetic anterior restorations. However, some systems are complex and technique sensitive. The authors describe a layering technique for the provision of direct aesthetic anterior composite restorations suitable for a general practice setting.

CLINICAL RELEVANCE

Aesthetic restorations can be provided directly and in a conservative manner using composite resin, often avoiding the need for more destructive indirect techniques.

Effect of the regional variability of dentinal substrate and modes of application of adhesive systems on the mechanical properties of the adhesive layer

Aim:

This study assessed the effect of the dentin depth and the application mode on the hardness and elastic modulus of the adhesive layer.

Materials and Methods:

Occlusal surfaces of 48 caries-free human third molars were removed, at two levels: Superficial and deep dentin. For each type of surface, the test specimens were randomly divided into groups which underwent the application: A conventional two-step adhesive system (Adper™ Single Bond [SB]) and self-etch adhesives system (Adper™ SE Plus [SE] and AdheSE^® [AD]). The adhesives applied were active or passive. Composite build-ups were constructed incrementally. The teeth were sectioned, embedded, and polished. The nanoindentation test was performed in the adhesive layer. The results were analyzed by ANOVA and Tukey tests.

Results:

In the adhesive layer, the higher hardness (0.307 ± 0.006 GPa) and elastic modulus (4.796 ± 0.165 GPa) of SE were obtained in superficial dentin in passive application. The elastic modulus of SE (4.115 ± 0.098 GPa) was lowest in active application in superficial dentin. The active application significantly increased the hardness of the SB in the deep dentin (0.011 ± 0.314 GPa) compared the superficial dentin (0.280 ± 0.010 GPa). For the AD, only the mode of application was statistically significant (P=0.0041) for the hardness, active application (0.289 ± 0.015 GPa) being higher than passive application (0.261 ± 0.013 GPa) (P=0.0042) in deep dentin.

Conclusion:

The experimental results reveal that the mechanical properties were influenced for the application mode of adhesive systems and dentin depth.

Durability of bonds and clinical success of adhesive restorations

Resin-dentin bond strength durability testing has been extensively used to evaluate the effectiveness of adhesive systems and the applicability of new strategies to improve that property. Clinical effectiveness is determined by the survival rates of restorations placed in non-carious cervical lesions (NCCL). While there is evidence that the bond strength data generated in laboratory studies somehow correlates with the clinical outcome of NCCL restorations, it is questionable whether the knowledge of bonding mechanisms obtained from laboratory testing can be used to justify clinical performance of resin-dentin bonds. There are significant morphological and structural differences between the bonding substrate used in in vitro testing versus the substrate encountered in NCCL. These differences qualify NCCL as a hostile substrate for bonding, yielding bond strengths that are usually lower than those obtained in normal dentin. However, clinical survival time of NCCL restorations often surpass the durability of normal dentin tested in the laboratory. Likewise, clinical reports on the long-term survival rates of posterior composite restorations defy the relatively rapid rate of degradation of adhesive interfaces reported in laboratory studies. This article critically analyzes how the effectiveness of adhesive systems is currently measured, to identify gaps in knowledge where new research could be encouraged. The morphological and chemical analysis of bonded interfaces of resin composite restorations in teeth that had been in clinical service for many years, but were extracted for periodontal reasons, could be a useful tool to observe the ultrastructural characteristics of restorations that are regarded as clinically acceptable. This could help determine how much degradation is acceptable for clinical success.

Effect of 3-year water storage on the performance of one-step self-etch adhesives applied actively on dentine

OBJECTIVES

To evaluate the effect of the application method on the immediate and 3-year resin-dentine bond strength (μTBS) and nanoleakage (NL) for 3 one-step self-etch adhesives (Adper Prompt L-Pop; Clearfil S(3) Bond and Xeno III).

METHODS

The occlusal enamel of 42 human molars were removed to expose a flat dentine surface. The adhesives were applied under inactive or active application. After light-curing (600mW/cm(2) for 10s), composite buildups were constructed incrementally and sectioned to obtain bonded sticks (0.8mm(2)) to be tested in tension immediately or after 3 years of water storage of water storage. For NL, 2 bonded sticks from each tooth at each time were coated with nail varnish, placed in silver nitrate and polished down with SiC paper. The μTBS data was submitted to a two-way repetead mesures ANOVA and Tukey's test for each adhesive (α=0.05).

RESULTS

The active application showed higher immediate and 3-year μTBS than the inactive application (p<0.05). An increase in the silver nitrate deposition was seen for all conditions after 3 years; however this was more pronounced for all materials under inactive application (p<0.05).

CONCLUSIONS

The active application improves the immediate bonding performance of the adhesive systems. Reductions of the bond strength were observed for all materials after 3 years, however reduced degradation rate was observed when the materials are applied actively in dentine.

Use of micro-Raman spectroscopy to investigate hybrid layer quality in demineralized root dentine

Treatment of early root caries using resin adhesives to stabilize demineralized dentine and deprive bacteria of nutrients is a recognized and conservative treatment option. Essential to its success is a stable resin-dentine interface, with effective infiltration of demineralized dentine and adequate resin curing. The objective of this study was therefore to examine degree of cure (DoC) and depth of penetration of dentine adhesives in demineralized dentine using micro-Raman spectroscopy. Three commercially available adhesives were applied essentially according to manufacturers' instructions to visibly wet demineralized dentine, with two coats of primer to reduce dilution. Specimens were sectioned perpendicular to the bonded interface and micro-Raman spectroscopy performed on the cross section. Molecules associated with the adhesive were detected to depths greater than 100 μm indicating a thicker hybrid layer than seen in sound dentine. The hybrid layer showed an increase in proportion of aliphatic C=C double bonds at the base of the hybrid layer, which may be a consequence of reduced DoC or phase separation. Micro-Raman spectra suggest deep zones contain an increased concentration of HEMA and a lower concentration of BisGMA, which is likely to be less stable and may contribute to early breakdown of the dentine adhesive interface.