Immediate human pulp response to ethanol-wet bonding technique

Equivalence study of the resin-dentine interface of internal tunnel restorations when using an enamel infiltrant resin with ethanol-wet dentine bonding

This preregistered ex vivo investigation examined the dentinal hybrid layer formation of a resinous infiltrant (Icon), with reference to both thickness (HLT) and homogeneity when combined with modified tunnel preparation (occlusal cavity only) and internal/external caries infiltration. The adhesives Syntac and Scotchbond MP were used as controls (Groups 1 and 3) or in combination with Icon (Groups 2 and 4). A split-tooth design using healthy third molars from 20 donors resulted in 20 prepared dentine cavities per experimental group. The cavity surfaces (n = 80) were etched (37% H3PO4), rinsed, and air-dried. Rewetting with ethanol was followed by application of the respective primers. After labeling with fluorescent dyes, either Syntac Adhesive/Heliobond or Scotchbond MP Adhesive was used alone or supplemented with Icon. HLT, as evaluated by scanning electron microscopy, did not significantly differ (P > 0.05), and confocal laser scanning microscopy revealed homogeneously mixed/polymerized resin-dentine interdiffusion zones in all groups. Icon can be successfully integrated into an ethanol-wet dentine bonding strategy, and will result in compact and homogeneous hybrid layers of comparable thickness considered equivalent to the non-Icon controls, thus allowing for preservation of the tooth's marginal ridge and interdental space in the case of internal/external infiltration of proximal caries.

Wet-bonding technique with ethanol may reduce protease activity in dentin-resin interface following application of universal adhesive system

Background

Greater degradation of the hybrid layer is expected when a universal adhesive system is used, especially in the conventional application strategy. Therefore, it would important to evaluate the effect of the ethanol (ETH) and a potential matrix protease inhibitor (caffeic acid phenethyl ester/ CAPE) to maximize the ability to achieve stable dentin bond strength. The aim of this study was to evaluated the effect of ETH on a wet-bonding technique, and dentin pretreatments with different concentrations of CAPE in ethanolic solution, followed by application of a universal adhesive system (Single Bond Universal) to inhibit proteolytic activity.

Material and Methods

Dentin blocks were allocated to eight experimental groups according to the strategy (total-etch our self-etch) and treatments: ETH, or dentin pretreatment with CAPE (at 0.5%, 2.5%; and 5.0%). Half of each block (each hemiblock) served as the control (without dentin pretreatments) for the same group. The bonding strategy was performed (adhesive system/ restoration with composite resin). Two slices were obtained from each hemiblock and evaluated using in situ zymography. The proteolytic activity was analyzed by quantifying the green photons of the images obtained under a fluorescence microscope in three dentin locations close to the dentin-resin interface: hybrid layer (HL), underlying dentin (UD) and deep dentin (DD).

Results

Wilcoxon tests (for comparison between experimental and control groups) and Friedman and Nemenyi tests (for comparisons between interface locations) showed that there was no difference between the groups with different CAPE concentrations and the respective control groups (p>0.05). ETH reduced the proteolytic activity at the HL and UD (p<0.05).

Conclusions

The wet-bonding technique with ETH proved effective in reducing the proteolytic activity. The use of CAPE in different concentrations solubilized in ethanol did not have a favorable effect on proteolytic inhibition. Key words:Adhesives, Hybrid layer, Dentin, Metalloproteinases.

The effect of ethanol wet bonding technique on postoperative hypersensitivity of Class II composite restorations: A randomized trial

Background

To evaluate the effect of Ethanol Wet Bonding Technique (EWBT) on postoperative hypersensitivity (POH) of composite restorations in premolar teeth.

Materials and Methods

In this randomized trial, 24 patients with at least three proximal carious lesions with similar axial depth and position of gingival floor in their premolars were enrolled. Following cavity preparation, the teeth were randomly assigned to one of three groups: (1) Class II resin-based composite (RBC) restoration using an etch-and-rinse adhesive + wet bonding technique (Control); (2) RBC restoration using EWBT + hydrophobic adhesive; and (3) RBC restoration using EWBT + hydrophilic adhesive. Tooth hypersensitivity was evaluated before and 1, 3, 7, 14 and 30 days after treatment according to the Visual Analog Scale. Data were analyzed statistically with Kruskal-Wallis and Friedman tests (P = 0.05).

Results

All teeth showed similar levels of hypersensitivity after treatment (both P > 0.05). Furthermore, there was no difference between POH levels of the test and control groups at any control period (P < 0.05). Friedman test indicated that the POH significantly reduced within time in all groups (P < 0.05).

Conclusion

Application of ethanol-wet bonding technique, either with hydrophobic or hydrophilic adhesives did not affect the POH of Class II composite restorations in premolars.

Morphological analysis and immunohistochemical expression in restorations with self-adhesive resin: A randomized split-mouth design-controlled study

Background

To evaluate the morphology and immunohistochemical expression of MMP-9, TIMP-3, COL-I, TNF-alfa and COX-2 in the dentinopulp complex of restorations with self adhesive composite (Vertise Flow/Kerr) compared with conventional resin composite with self-etching adhesive (Filtek Z250/3M ESPE and Clearfil SE Bond/Kuraray-Noritake).

Material and Methods

A randomized, controlled, double-blind, split-mouth, two-arm clinical trial was conducted. Twenty-seven volunteers with third molars indicated for extraction received two deep class I restorations, one with each material. The morphology and immunohistochemical expression were measured at 15 days after the restorative procesures. The data were submitted to the Fisher`s Exct test (α=0.05).

Results

Through morphological analysis, a slight disorganization of the odontoblastic layer was visualized, along with a slight inflammatory infiltrate in the VERT and CSEB groups (p< 0.05). In immunohistochemical analysis, TNF-alpha, MMP-9, TIMP-3 and COX-2 demonstrated more cases of positive pulp labeling.

Conclusions

Self-adhesive resin composite and conventional resin composite with a self-etching bonding agent promoted slight alterations in the dentin-pulp complex, indicating a repair ability and reversibility of the inflammatory process against aggressions of the adhesive restorative procedure. Key words:Immunohistochemistry, inflammation, randomized clinical trial, self-adhering composite, dentistry.

Response of pulp cells to resin infiltration of enamel white spot-like lesions

OBJECTIVES

To investigate the trans-enamel and trans-dentinal biological effects of treating enamel white spot-like lesions (EWSLs) with resin infiltration components (RICs) on odontoblast-like cells (MDPC-23) and human dental pulp cells (HDPCs).

METHODS

EWSLs were induced in 60 enamel/dentin discs (4.0 ± 0.2 mm thick) using S. mutans. The discs were adapted into artificial pulp chambers and MDPC-23 were seeded on the dentin surface. The components of a resin infiltration system (Icon) were applied individually or in combination on the enamel surface as following (n = 10/treatment): Etch, Infiltrant, Etch+Infiltrant, or Etch+Dry+Infiltrant. The application of water or hydrogen peroxide served as negative and positive controls, respectively. After 72 h, MDPC-23 viability was evaluated. The extracts were exposed for 72 h to pre-cultured MDPC-23 and HDPCs in 96-well plates to evaluate cell viability, alkaline phosphatase activity (ALP), mineralized nodule formation (MN), and the expression of inflammatory cytokines (ICs) and mineralization-related genes (MRs). Data were analyzed by ANOVA complemented with Tukey or Games-Howell post-hocs (α = 5%).

RESULTS

Cell viability, ALP activity, and MN formation were significantly reduced in response to the RICs, presenting intermediate values compared to positive and negative controls. Likewise, ICs were upregulated, whereas MRs were downregulated. Among the RICs, the Etch component caused the most notorious detrimental effects.

SIGNIFICANCE

Resin infiltration of EWSLs negatively affected the metabolism of pulp cells in vitro. Therefore, even though resin infiltration is a micro-invasive therapy for non-cavitated caries in enamel, it should be closely followed up seen that components may diffuse and unbalance pulp homeostasis.

Resinous adhesive systems differentially affect the expression of cytokines by human monocytes stimulated or not with Streptococcus mutans in vitro

OBJECTIVES

The polymerization of adhesive systems is incomplete and the residual monomers that have been released have a cytotoxic capacity. Some teeth develop into pulp necrosis after composite resin restorations. Considering frequent pulpal inflammation in response to cariogenic bacteria, substances released from the patches could affect the cells of the inflammatory infiltrate and interfere with the mechanisms of defense against microorganisms and protection of pulpal tissue. The aim of this study was to evaluate the effect of substances released by different resinous adhesive systems on cell viability and cytokine expression by human monocytes stimulated in vitro with Streptococcus mutans.

DESIGN

Peripheral blood mononuclear cells from 10 healthy subjects were stimulated with S. mutans and then incubated with supernatants obtained from the Single Bond Universal (SBU) or Clearfil SE Bond (CSEB) adhesive systems for eight hours. Staining with Annexin V and 7AAD for analysis of apoptosis were performed and detection of monocytes expressing cytokines IL-1α, IL-6, IL-8, IL-10, IL-12 and TNF-α were performed by flow cytometry.

RESULTS

No treatment significantly affected apoptosis in monocytes. SBU supernatant increased the frequency of monocytes expressing IL-8 and decreased the monocytes expressing IL-10. Considering S. mutans-stimulated cells, while SBU increased the frequency of IL-8⁺ monocytes, CSEB reduced the frequency of IL-6 and TNF-α positive monocytes.

CONCLUSIONS

Products released from SBU seem to induce proinflammatory effects on monocytes while those from CSEB show an anti-inflammatory outcome. These effects may interfere in the control of cytokine-mediated immunoinflammatory pulp reactions, both in the presence and absence of stimulation by cariogenic bacteria.

Six-month performance of restorations produced with the ethanol-wet-bonding technique: a randomized trial

This double-blind randomized controlled clinical trial evaluated the effectiveness of dentin pretreatment with 100% ethanol (EWBT - ethanol wet bonding technique) and different adhesive protocols in noncarious cervical lesions (NCCL) after 6 months. Patients presenting at least one NCCL were included. NCCLs (n=148) were randomly assigned to 4 groups: NE (Non-EWBT + three-step etch-and-rinse (Scotchbond Multi Purpose, 3M ESPE [MP]), E (EWBT + MP); EB (EWBT + [Bond - third step of MP]), and EU (EWBT + universal adhesive (Single Bond Universal, 3M ESPE). Conventional acid-etching (Condac 37%, FGM) and nanohybrid resin composite (Z350, 3M ESPE) were used. Trained and calibrated examiners (Kappa = 0.61) evaluated the restorations at baseline (7 days) and 6-month recall using the USPHS modified criteria. Data were subjected to Chi square (α = 0.05). Differences in the success rate were found for the treatments (p = 0.003). EB presented the lowest success rate compared with the other groups (p < 0.02). No significant differences were detected among NE, E, and EU (p > 0.49). The survival rates were 97.23%, 97.30%, 78.95%, and 97.30% for NE, E, EB, and EU, respectively. Regarding postoperative sensitivity, a significant reduction was found for groups E (p = 0.027) and EU (p < 0.01) after 6 months. After 6 months, EWBT associated to the hydrophobic adhesive system had the highest failure rate.

Influence of ethanol-wet dentin, adhesive mode of application, and aging on bond strength of universal adhesive

The aim of this study was to evaluate the effect of ethanol on the bond longevity of a universal adhesive system to bovine dentin, under different modes of adhesive application and artificial aging. Bovine dentin was exposed, and the smear layer was standardized by sandpaper polishing. Specimens were randomly divided into 2 groups: ethanol (E) and non-ethanol (N). Groups were subdivided according to adhesive mode of application into etch-and-rinse (Er) and self-etching (S). Resin blocks were built onto the treated surface, and the specimens were stored in deionized water at 37°C for 48 h. Half of the specimens (n = 10) were subjected to thermomechanical aging (A for aged and Na for non-aged). Resin/dentin beams were obtained and subjected to microtensile test in a universal testing machine. Data were analyzed using a three-way ANOVA and Tukey's tests (α = 5%). There was interaction among the three factors (p=0.0003). The use of ethanol resulted in higher values, except for the Er and Na groups (E_Er_Na = N_Er_Na). The mode of application was similar, except for the N and A groups (N_S_A > N_Er_A). For the A groups, the values were lower, except in the cases using ethanol, in which the results were not affected. The study concluded that the use of ethanol resulted in higher microtensile bond strength values, even after aging. The mode of adhesive application did not influence the results.

The effect of dental pulp-capping materials on hard-tissue barrier formation: A systematic review and meta-analysis

BACKGROUND

The authors of this systematic review aimed to compare the effects of pulp-capping materials on hard-tissue barrier formation using histologic assessments.

TYPE OF STUDIES REVIEWED

The authors included randomized controlled trials and controlled clinical trials in humans, with vital therapies performed on healthy permanent teeth undergoing experimental mechanical pulp exposures. They searched electronically in the PubMed, Cochrane, Embase, and Summon databases and carried out a manual search. Twenty-seven full-text articles were eligible for inclusion in the systematic review. After data extraction, the authors performed 2 sets of meta-analyses with odds ratios (OR) and their 95% confidence intervals (CI) on 22 studies. Ten studies compared mineral trioxide aggregate (MTA) with calcium hydroxide (CH), and 12 compared bonding agents with CH. The authors assessed bias by means of Cochrane Collaboration's tool for assessing risk, funnel plots, and Harbord test.

RESULTS

The use of MTA was associated with a higher rate of hard-tissue barrier formation than CH. The OR comparing the 2 groups was 2.45 (95% CI, 1.39 to 4.29; P = .002). Use of bonding agents was associated with a lower rate of hard-tissue barrier formation than CH. The OR comparing the 2 groups was 0.02 (95% CI, 0.01 to 0.05; P < .001).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The results suggest that MTA and CH have positive effects on hard-tissue barrier formation. On the basis of the evidence, the authors conclude that MTA has better effects than CH regarding dental pulp protection in the capping of mechanical pulp exposures. Conversely, bonding agents are inferior to CH.

Biological Effects of Provisional Resin Materials on Human Dental Pulp Stem Cells

OBJECTIVES

This study investigated the in vitro cytotoxicity as well as the proinflammatory cytokine expression of provisional resin materials on primary cultured human dental pulp stem cells (hDPSCs).

METHODS

Five commercially available provisional resin materials were chosen (SNAP [SN], Luxatemp [LT], Jet [JE], Revotek LC [RL], and Vipi block [VB]). Eluates that were either polymerizing or already set were added to hDPSCs under serially diluted conditions divided into three different setting times (25% set, 50% set, and 100% set) and incubated for 24 hours with 2× concentrated culture media. Cell cytotoxicity tests were performed by LDH assay and live and dead confocal microscope images. The expression of proinflammatory cytokines in SN and VB was measured using cytokine antibody arrays. Data were analyzed using repeated measures analysis of variance (ANOVA) or ANOVA followed by the Tukey post hoc test at a significance level of p<0.05.

RESULTS

Cytotoxicity greater than 30% was observed in the 50% diluted culture in SN, LT, and JE in the already set stage (p<0.05), while it was detected in SN and LT in early or intermediate stage samples. The cytotoxicity of SN, JE, and LT was greater with eluates from the polymerizing phase compared to that from already set samples (p<0.05), as observed by live and dead images. On the other hand, RL and VB did not exhibit cytotoxicity greater than 30%. Proinflammatory cytokines were not detected in 12.5% diluted culture with eluates from VB and early set stage SN.

CONCLUSIONS

The eluates from chemical-activated provisional resin materials during polymerization (SN, LT, and JE) were cytotoxic to hDPSCs and may adversely affect pulp tissue.

Cytotoxicity and proinflammatory cytokine expression induced by interim resin materials in primary cultured human dental pulp cells

STATEMENT OF PROBLEM

Acrylic resin materials for interim restoration may adversely affect pulp tissue during the polymerization phase.

PURPOSE

The purpose of this in vitro study was to determine the cytotoxic and proinflammatory cytokine production effects induced by interim resin materials in primary cultured human dental pulp cells (hDPCs).

MATERIAL AND METHODS

Five interim resin materials were evaluated: 3 types of chemically activated products, 1 light-activated product, and 1 computer-aided design and computer-aided manufacturing (CAD-CAM) product. After obtaining eluates from interim resin materials that either were in the process of polymerizing or were already polymerized, these extracts were cocultured with hDPCs under serially diluted conditions (50%, 25%, 12.5%, 6.25%, and 3.125%) for 24 hours with positive (1% phenol) and negative (distilled water) controls. A cell viability assay with tetrazolium was used to evaluate toxic effects on the cells, and images of both live and dead cells were captured using confocal microscopy. Proinflammatory cytokine levels were measured using cytokine antibody arrays. All experiments were independently repeated 3 times, and data were analyzed using 1-way ANOVA and post hoc Tukey honest significant differences test (α=.05).

RESULTS

Cell viabilities less than 70% were observed from the eluates of the 3 chemically activated products under the 50% conditions. Among the chemically activated products, the adverse effects were significantly greater with eluates derived from the polymerizing phase compared than those that had already polymerized, as shown by confocal microscopy images of live and dead cells. However, the light-activated and CAD-CAM-fabricated products did not adversely affect the hDPCs. Significantly increased levels of proinflammatory cytokines were not detected in 12.5% of extract from polymerizing compared with distilled water control.

CONCLUSIONS

The 50% eluates derived from chemically activated interim resin during the polymerizing phase were cytotoxic to hDPCs and may adversely affect pulp tissue. Recommendations such as excess washing are necessary during fabrication.

Inhibition of hybrid layer degradation by cavity pretreatment: Meta- and trial sequential analysis

OBJECTIVES

Inhibition of hybrid layer degradation, for example via inhibition of matrix-metallo-proteinases (MMP) could reduce risk of retention loss and failure of adhesively placed restorations. This systematic review investigated such inhibitory pretreatment qualitatively and via meta- and trial-sequential-analysis.

DATA SOURCES

We included randomized clinical trials comparing degradation inhibitory cavity pretreatment versus no, placebo or alternative treatments prior adhesive placement of resin-based restorations. Trials reporting retention loss or failure (graded bravo-delta in USPHS or similar criteria) were included. Trial selection, data extraction, and risk of bias assessment were conducted independently by two reviewers. Fixed- or random-effects intention-to-treat, per-protocol, and scenario meta-analyses were performed, and trial-sequential-analysis used to control for risk of random errors. Electronic databases (PubMed, Embase, Cochrane CENTRAL) were systematically screened, and hand searches and cross-referencing performed.

STUDY SELECTION

The ten included trials involved 208 patients (695 cavities) and used chlorhexidine (seven trials), ethanol-wet-bonding (two trials), and quaternary ammonium compounds for degradation inhibition. All but one trial had high risk of bias. Follow-up ranged from 6 to 36 months. Risk of retention loss was not significantly decreased after pretreatment (per-protocol OR [95% CI] 1.37 [0.68/2.77], intention-to-treat: 1.25 [0.76/2.04]). This was found for risk of restoration failure as well (per-protocol: 0.86 [0.56/1.34], intention-to-treat: 1.22 [0.83/1.80]). Scenario analyses found great uncertainty introduced by attrition. According to trial sequential analysis, no firm evidence was reached.

CONCLUSIONS

There is insufficient evidence to recommend or refute degradation inhibitory cavity pretreatment prior adhesively placing resin-based restorations. This may change if teeth are followed-up for longer.

CLINICAL SIGNIFICANCE

Dentists can perform cavity pretreatments for inhibition of hybrid layer degradation, but a beneficial effect is not supported by sufficient evidence. The impact of further effects (e.g. disinfection, pulp-irritation) remains unclear.

A review of ethanol wet-bonding: Principles and techniques

Conventional water wet-bonding technique has been advocated by many scientists, but the excess water will induce suboptimal polymerization of dental adhesives, phase separation, and nanoleakage, which will influence the longevity of resin-dentin interfaces. Recent studies have put forward a new concept, ethanol wet-bonding. This technique can increase in dentin bond durability. This review focuses on the principles of ethanol wet-bonding, its surface treatment methods.