Performance of a universal adhesive on etched and non-etched surfaces: Do the results match the expectations?

The Influence of Chlorhexidine Gluconate Dentine Pre-Treatment on Adhesive Interface and Marginal Sealing

Background and Objectives: The aim of this in vitro study was to evaluate the combined effect of a 2% chlorhexidine aqueous solution and a universal adhesive system applied in self-etch and etch-and-rinse strategies on the composite resin-dentin interface. Materials and Methods: Class V cavities were prepared on the facial and lingual surfaces of forty caries-free molars extracted for orthodontic reasons. The samples were randomly divided into two groups corresponding to the used etching protocol: I-etch-and-rinse; II-self-etch. In each tooth, one cavity was assigned for the control subgroups -IA (n = 20) and IIA (n = 20)-adhesive only, and the opposite cavity was pretreated with a 2% chlorhexidine solution-Gluco CHeX Cerkamed-subgroups IB (n = 20) and IIB (n = 20). Both sets of groups were restored using a universal adhesive system (Single Bond Universal Adhesive, 3M-ESPE) and a bulk-fill composite resin (Filtek One Bulk Fill Restorative, 3M-ESPE). The roots and the pulp tissue were then removed, and a needle connected to a perfusor with 100 mL saline solution was used for pulp pressure simulation with a hydrostatic pressure of 20 cm H₂O. Cariogenic attack was simulated using a demineralizing solution for 3 days at a constant temperature of 25 °C. The teeth were then sectioned in a facial-lingual direction and the microleakages at the occlusal and cervical margins were registered and scored using an optical Carl-Zeiss AXIO Imager A1m microscope (Carl-Zeiss). The composite resin-dentin interface was analyzed using a SEM Vega Tescan LMH II. Statistical analysis was performed using the Kruskal-Wallis test with a significance level of p < 0.05. Results: Microleakage evaluation showed no significant differences among the study groups (p > 0.05). In subgroup IA, significant differences were recorded between occlusal and cervical margins (p < 0.05). Conclusions: Application of chlorhexidine on tooth substrate before using a universal bonding system in total etch or self-etch mode has no influence on the adhesive interface in the condition of cariogenic attack. The thickness of the adhesive resin layer seems to be less uniform when using chlorhexidine, but the morphological differences at the adhesive interface have no influence on the sealing capacity of the universal bonding system, regardless of the etching strategy.

Impact of cleansing protocols to remove endodontic sealer residues on the adhesive interface: Bonding with universal adhesive systems

OBJECTIVE

The aim of this study was to evaluate the effectiveness of cleansing protocols to remove sealer residues using different cleaning strategies and the effect of bond strength of two universal adhesives to dentin impregnated with epoxy resin-based sealer.

MATERIALS AND METHODS

Fifty bovine dentin specimens were impregnated with epoxy resin-based sealer containing calcium hydroxide (Sealer Plus) and submitted to cleansing protocols (n = 10): negative control (NC), positive control (PC), 95% ethanol (ET), xylol (XI), and amyl acetate (AA). Specimens were evaluated by scanning electron microscope (SEM). Other 100 specimens were submitted to the same protocols (n = 20). Each protocol was divided into subgroups (n = 10) according to the universal adhesive system used: Scotchbond Universal (SU); Ambar Universal (AU). Bond strength was evaluated by micro-shear bond test (μSBT). Persistence of residues data were assessed with Kruskal-Wallis and Dunn's tests. μSBT data were analyzed with two-way ANOVA (α = 5%).

RESULTS

ET presented higher persistence of residues compared to AA and XI (p < 0.05). AA and XI were similar from each other (p > 0.05). AU and SU presented similar μSBT values, regardless of the cleansing solution (p > 0.05). SU-NC presented the highest μSBT among all conditions (p < 0.05).

CONCLUSION

The bond strength of universal adhesives was not affected by different amounts of sealer residues after different cleaning protocols.

CLINICAL SIGNIFICANCE

Non-polar substances such as amyl acetate and xylol are effective for removing residues from epoxy resin-based endodontic sealers.

Influence of acidic monomer concentration and application mode on the bond strength of experimental adhesives

The aim of this research was to evaluate the influence of MDP (10-methacryloyloxydecyl dihydrogen phosphate) concentration and application mode of experimental adhesives on microshear bond strength (μSBS) to dentin after storage in distilled water at 37°C for 24h and 6 months. Five experimental adhesives were prepared with: CQ, DABE, BHT, ethanol, HEMA, TEGDMA, Bis-EMA, UDMA, and Bis-GMA. Concentrations of 0 wt%, 3 wt%, 9 wt%, 12 wt% or 15 wt% of MDP were added to their composition. The adhesives were applied to flat dentin surfaces in etch-and-rinse or self-etching modes. Cylindrical molds filled with light-cured composite resin were placed above the dentin. The specimens were stored in distilled water at 37oC for 24h or 6 months and submitted to μSBS testing. The adhesives were also submitted to pH analysis. The data were analyzed by one-way ANOVA, three-way ANOVA and Tukey's test (α = 5%). All the adhesives used in the etch-and-rinse mode showed significantly higher bond strength than the adhesives applied in the self-etching approach. The 9 wt% adhesive showed the highest bond strength values, and 3 wt% was most stable after storage. A strong negative correlation between MDP concentration and pH was observed. It was concluded that the formulations with low concentrations of MDP (up to 9 wt%) showed better results for bond strength and bond strength degradation over time.

Influência do selamento dentinário imediato com sistema adesivo universal na resistência de união

Resumo Introdução O selamento dentinário imediato consiste na aplicação imediata de um sistema adesivo sobre exposições dentinárias após o preparo dental e previamente aos procedimentos de moldagem. Objetivo O objetivo do estudo foi avaliar a influência do selamento dentinário imediato (SDI) na resistência adesiva do sistema adesivo universal (Single Bond Universal, 3M ESPE) em dentina, na forma de aplicação autocondicionante. Material e método 30 incisivos bovinos foram divididos em 3 grupos (n = 10): grupo S (Sem Selamento Dentinário Imediato), grupo SDI (Selamento Dentinário Imediato) e grupo SDIF (Selamento Dentinário Imediato + Resina Flow). A superfície vestibular foi desgastada com pontas diamantadas até a exposição superficial de dentina. A simulação da lama dentinária foi realizada com lixa d’água por 30s e a dentina tratada de acordo com o respectivo grupo. Para simulação da restauração provisória, foram cimentados blocos de resina bisacrílica com cimento de óxido de zinco. Após 7 dias, foi realizada a cimentação definitiva de blocos de resina com cimento resinoso dual (RelyX ARC, 3M ESPE). Os espécimes foram seccionados para obtenção de filetes de 1mm2 e submetidos ao teste de microtração, em uma máquina universal de ensaios (Instron). Os resultados foram tabulados e submetidos a Análise de Variância (ANOVA) e teste de Tukey a 5% de significância. Resultado Observaram-se maiores valores de resistência de união para o grupo SDIF (23,53 MPa), diferindo estatisticamente do Grupo S (17,65 MPa) (p=0,008). O grupo SDI apresentou valor médio de resistência de união (19,25 MPa), não diferindo estatisticamente dos grupos S (p=0,68) e SDIF (p=0,07). Conclusão Recomenda-se a técnica de selamento dentinário imediato seguido da uma camada de resina flow, em exposições dentinárias ocasionadas pelo preparo dental para restaurações indiretas.

Influence of different application protocols of universal adhesive system on the clinical behavior of Class I and II restorations of composite resin - a randomized and double-blind controlled clinical trial

Background

Multimode adhesives incorporate the versatility of adapting to various clinical situations by its capacity to be used in different protocols. This study aimed to evaluate the clinical behavior of composite resin direct restorations (Class I and II) performed with different universal dentin adhesive application protocols comparing adapted FDI and adapted USPHS criteria.

Methods

The current study is a randomized, double-blind, split-mouth, and convenience sample controlled clinical trial. The participants (age ≥ 18 years) had restorative need of Class I and/or II due to the presence of carious lesions and/or unsatisfactory restorations in at least three dental elements. Each participant received three application protocols for Scotchbond Universal adhesive (3M ESPE), one in each tooth to be restored: ER = etch-and-rinse + adhesive (n = 50); SEE = selective enamel etch + adhesive (n = 50) and SE = self-etch adhesive (n = 50). All teeth were restored in a similar way using Filtek™ Supreme composite resin (3M ESPE). Restorations were evaluated using the adapted FDI and adapted USPHS criteria, at baseline after 7 to 21 (12.02 ± 5.68) days (T1; n = 50 per group) and after 12 to 20 (15.8 ± 2.7) months (T2; n = 46 per group) by two previously calibrated evaluators (Kappa > 0.80). The statistical tests were performed between groups (Friedman), intragroup (Wilcoxon), and between the criteria considering acceptable and not acceptable restorations (McNemar), α = 0.05.

Results

A statistically significant difference was observed only for the property “superficial staining”, between groups at T2 (p = 0.01) for ER (n = 13 with score 2 or more) and SEE (n = 3 with score 2 or more) and intragroup for ER (T1, n = 1 with score 2 or more; T2, n = 13 with score 2 or more, p = 0.001) and SE (T1, n = 0 with score 2 or more; T2, n = 8 with score 2 or more p = 0.007). For the other comparisons between groups, intragroup, and between the adapted FDI and adapted USPHS criteria, there were no statistically significant differences (p ≥ 0.05).

Conclusions

It can be concluded that the different application protocols of the universal adhesive resulted in clinically “acceptable” restorations after 15.8 ± 2.7 months of follow-up. Adapted FDI and adapted USPHS criteria provided similar results to each other.

Trial registration.

Number in Brazilian Registry of Clinical Trials (ReBEC): RBR-9p3hdp. Registered 24 May 2015.

High Bond Durability of Universal Adhesives on Glass Ceramics Facilitated by Silane Pretreatment

Objective:

This study aimed to investigate the long-term effectiveness of ceramic–resin bonding with universal adhesives in non–silane-pretreated and silane-pretreated modes after 10,000 cycles of thermal aging.

Methods and Materials:

All Bond Universal, Adhese Universal, Clearfil Universal Bond, and Single Bond Universal were selected. Etched lithium disilicate glass ceramics were prepared, randomly assigned to groups, and pretreated with or without ceramic primer containing silane coupling agent prior to the application of universal adhesive (ie, silane-pretreated or non–silane-pretreated mode). The shear bond strength (SBS), microleakage, and field-emission scanning electron microscopy images of the ceramic–resin interfaces were examined after 24 hours of water storage or 10,000 thermal cycles. Light microscopy and confocal laser scanning microscopy (CLSM) were performed to analyze marginal sealing ability.

Results:

SBS and microleakage percentage were significantly affected by bonding procedure (non–silane-pretreated or silane-pretreated mode) and aging (24 hours or 10,000 thermal cycles). After the universal adhesives in the non–silane-pretreated mode were aged, SBS significantly decreased and microleakage percentage increased. By contrast, the SBS of Adhese Universal, Clearfil Universal Bond, and Single Bond Universal decreased, and the microleakage percentage of all of the adhesives increased in the silane-pretreated mode. However, after aging, the SBS of the silane-pretreated groups were higher and their microleakage percentages lower than those of the non–pretreated groups. In the non–silane-pretreated mode, adhesive failure was dominant and gaps between composite resin and the adhesive layer were significant when observed with CLSM.

Conclusions:

The simplified procedure reduced the ceramic–resin bonding effectiveness of universal adhesives after aging, and additional silane pretreatment helped improve the long-term durability.