Bond strength of self-adhesive resin cements to dentin after antibacterial and chelating solution treatment

Micro Push-Out Bond Strength of Resin Composite to Dentin in Primary Dentition Using Three Universal Adhesives with Different pH: An In Vitro Study

To evaluate the bond strength of different universal adhesives on deciduous tooth dentineand their relationship with the composition and potential of hydrogen (pH). Methods: An in vitromicro push-out test on 150 samples (n = 50) per group per adhesive, namely, Adhese Universal(ADH; Ivoclar Vivadent), Futurabond U (FUT; Voco GmbH) (Test), and Scotchbond Universal withpre-conditioning (SCO; 3M) (Control), to record bond strength (BS) and type of adhesive failure.Results: The results of the different adhesives (megapascals (MPa)) varied, showing no statisticalsignificance. The corresponding averages are in MPa: ADH, 13.66 2.81; FUT, 14.48 2.88; SCO,14.98 3.96. Additionally, the frequency of type of failure was as follows: mixed (60.7%), adhesive(27.3%), and cohesive (12%). Conclusions: SCO, with a pH of 2.7, showed greater resistance tofracture, while FUT, with a pH of 2.3 and no pre-conditioning, approached the same values, being aone-step adhesive. No relationship was found between failure and type of adhesive.

Efficacy of different endodontic irrigation protocols on shear bond strength to coronal dentin

Aim

The purpose of this study was to evaluate the effect of etidronic acid on bond strength to coronal dentin.

Materials and Methods

A total of 75 human mandibular molars were sectioned 3 mm below the occlusal surface and then randomly divided into five groups according to irrigation solution used (n = 15): Group 1: 5 ml 2.5% sodium hypochlorite (NaOCl) +5 ml distilled water; Group 2: 5 ml 2.5% NaOCl + 5 ml 17% ethylenediaminetetraacetic acid (EDTA); Group 3: 10 ml mixture of 5% NaOCl and 18% 1-hydroxyethylidene-1,1-bisphosphonate (HEBP); Group 4: 5 ml mixture of 5% NaOCl and 18% HEBP + 5 ml 17% EDTA; and Group 5: 5 ml mixture of 5% NaOCl and 18% HEBP + 5 ml distilled water. Thereafter, Clearfil SE bond was applied to the dentin surfaces and then, composite build-ups were created using Tygon tubes for the microshear bond strength test. Data were analyzed using the one-way analysis of variance and Tukey test.

Results

When compared to Groups 3, 4, and 5, Groups 1 and 2 showed significantly higher bond strength values (P < 0.05). However, there was no statistically significant difference between Groups 1 and 2 and between Groups 3, 4, and 5 (P > 0.05).

Conclusion

HEBP adversely affected the bond strength of the tested adhesive to coronal dentin.

Influence of 2% chlorhexidine on pH, calcium release and setting time of a resinous MTA-based root-end filling material

The addition of chlorhexidine (CHX) to a resinous experimental Mineral Trioxide Aggregate (E-MTA) based root-end filling material is an alternative to boost its antimicrobial activity. However, the influence of chlorhexidine on the properties of this material is unclear. The aim of this study was to evaluate the influence of 2% chlorhexidine on the pH, calcium ion release and setting time of a Bisphenol A Ethoxylate Dimethacrylate/Mineral Trioxide Aggregate (Bis-EMA/MTA) based dual-cure experimental root-end filling material (E-MTA), in comparison with E-MTA without the addition of CHX and with conventional white MTA (W-MTA). The materials were placed in polyethylene tubes, and immersed in deionized water to determine pH (digital pH meter) and calcium ion release (atomic absorption spectrometry technique). The setting time of each material was analyzed using Gilmore needles. The data were statistically analyzed at a significance level of 5%. E-MTA + CHX showed an alkaline pH in the 3 h period of evaluation, the alkalinity of which decreased but remained as such for 15 days. The pH of E-MTA + CHX was higher than the other two materials after 7 days, and lower after 30 days (p < 0.05). All of the materials were found to release calcium ions throughout the 30 days of the study. The addition of CHX increased the calcium ion release of E-MTA to levels statistically similar to W-MTA. E-MTA showed shorter initial and final setting time, compared with W-MTA (p < 0.05). The addition of 2% CHX to MTA prevented setting of the material. The addition of CHX to E-MTA increased its pH and calcium ion release. However, it also prevented setting of the material.

Effects of different irrigating solutions and disinfection methods on push-out bond strengths of fiber posts

OBJECTIVE

The aim of this study was to evaluate the effects of various irrigating solutions and photoactivated disinfection (PAD) on the push-out bond strengths of fiber posts to root dentin.

MATERIALS AND METHODS

Thirty-two human teeth were divided into eight groups, as follows: (1) irrigation with physiologic saline (control), (2) NaOCl irrigation, (3) chlorhexidine (CHX) irrigation, (4) ethanol (EtOH) irrigation, (5) NaOCl followed by 17% EDTA irrigation, (6) NaOCl-EDTA supplemented with CHX irrigation, (7) NaOCl-EDTA supplemented with EtOH irrigation and (8) NaOCl-EDTA irrigation supplemented with PAD. After the posts were cemented, the roots were transversally sectioned to obtain four slices (1 mm thick) (n = 16). Push-out tests were conducted by applying a load at 0.5 mm/min, types of fracture failures were recorded and data were analyzed with one-way ANOVA and Tukey post-hoc tests (p = 0.05).

RESULTS

Push-out bond strength was significantly affected by the type of irrigating solution and the disinfection protocol (p < 0.05). The bond strength of the EtOH, NaOCl and NaOCl-EDTA-CHX irrigated groups was significantly higher than that of the other groups. The highest bond strength was observed in the EtOH irrigated group and the lowest was the NaOCl-EDTA irrigated group.

CONCLUSIONS

Irrigation with NaOCl and EDTA combined caused lower bond strength than observed in the control group. However, supplementing this combination with CHX improved the post-dentin bond strengths; supplementing with PAD did not.

Does inhibition of proteolytic activity improve adhesive luting?

Endogenous enzymes may be involved in the biodegradation of adhesive restoration-tooth interfaces. Inhibitors of matrix metalloproteinases (MMPs) have been suggested to retard the bond-degradation process. Limited data are available on whether composite cements may also benefit from MMP inhibitors. Therefore, the aim of this study was to determine the effect of two MMP inhibitors--chlorhexidine digluconate (CHX) and galardin--on the microtensile bond strength (μTBS) of two self-adhesive composite cements to dentin. Ceramic specimens were cemented to bur-cut dentin surfaces using the self-adhesive composite cements RelyX Unicem 2 (3M ESPE) or Clearfil SA (Kuraray), or the etch-and-rinse composite cement Nexus 3 (Kerr) that served as the control. The surfaces were left untreated or were pretreated with MMP inhibitors (2% CHX or 0.2 mM galardin). The μTBS was determined 'immediately' and upon ageing (water storage for 6 months). Statistical analysis revealed a significant effect of the factors 'composite cement' and 'storage', as well as all interactions, but no effect of the MMP inhibitors. After 6 months of ageing, the μTBS decreased for all cements, except for the multistep etch-and-rinse luting composite when it was applied without MMP inhibitors. The MMP inhibitors could not prevent the decrease in μTBS upon ageing and therefore do not improve the luting durability of the composite cements tested.