The effect of 2% chlorhexidine iontophoresis on dentin sealing ability of etch-and-rinse adhesive: An in vitro study

Background/purpose

Iontophoresis could enhance the delivery of chlorhexidine into oral tissue. This study aimed to determine the effect of 2% chlorhexidine iontophoresis (CHI) on the sealing ability of etch-and-rinse adhesive in human dentin using hydraulic conductance (HD) measurement, scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS).

Materials and methods

Thirty-nine sound dentin specimens were prepared from 39 extracted intact third molars. Thirty specimens were used for HD measurement and randomly divided into 3 equal-sized groups; (1) No chlorhexidine treatment (control), (2) passive chlorhexidine treatment (CHT) and (3) CHI on acid-etched dentin. Each dentin surface was treated with etch-and-rinse adhesive. HD of each specimen was measured before treatment, after immediate bonding and after 14 days. The other 9 specimens were subjected to SEM-EDS analysis of the acid-etched dentin and the dentin treated with CHT and CHI. ANOVA test and Student-Newman-Keuls method were used for statistical analysis.

Results

After bonding, there was no significant difference in percentage decrease of HD among the treatment groups (P > 0.05). After 14 days, CHI and CHT groups had greater percentage decrease of HD than the control (P < 0.001 and P = 0.009, respectively). Under SEM-EDS analysis, acid-etched dentin with CHI presented opened dentinal tubule orifices and more chlorhexidine precipitates on dentin than the dentin with CHT, which strongly related to a higher percentage of chloride ions on the CHI dentin surface (P < 0.001).

Conclusion

The use of CHI on acid-etched dentin had a positive effect on dentin sealing ability of etch-and-rinse adhesive.

Thirty-six-month follow-up of cervical composite restorations placed with an MDP-free universal adhesive system using different adhesive protocols: a randomized clinical trial

OBJECTIVES

To evaluate the influence of different application strategies on the clinical behavior of an MDP-free universal adhesive placed in non-carious cervical lesions (NCCLs) over the course of 36 months.

MATERIALS AND METHODS

Thirty-one patients participated in this study (N = 31). One hundred twenty-four restorations were assigned to four groups: We used the self-etch strategy on groups with (SE-et) and without (SET) selective enamel etching, and the etch-and-rinse strategy on groups with dry (ER-D) and moist (ER-M) dentin. After applying the MDP-free universal adhesive (Xeno Select universal adhesive, Dentsply Sirona), cavities were filled using EvoluX composite resin (Dentsply Sirona). The restorations were evaluated at baseline and after 36 months according to World Dental Federation (FDI) and US Public Health Service (USPHS) criteria. Friedman's repeated-measures analysis of variance rank (α = 0.05) was used for statistical analysis.

RESULTS

We evaluated the 31 patients after 36 months. Forty-two restorations were lost (ER-D = 5, ER-M = 7, SE-et = 14, SET = 16). The 36-month retention/fracture rates (95% confidence interval) were 83.9% for ER-D, 77.4% for ER-M, 54.9% for SE-et, and 48.4% for SET. ER strategy showed better retention rate than SE strategy (p < 0.05). Thirty-four restorations (ER-D = 6, ER-M = 10, SE-et = 10, SET = 8) showed marginal staining per FDI criteria and 15 restorations (ER-D = 1, ER-M = 2, SE-et = 6, SET = 6) showed marginal staining per USPHS criteria. No restorations showed postoperative sensitivity or recurrence of caries.

CONCLUSION

The retention rate of Xeno Select universal adhesive was poor, mainly in the self-etch strategy.

TRIAL REGISTRATION

REBEC clinical registry under protocol RBR-4wh4sh.

CLINICAL RELEVANCE

MDP-free universal adhesive behavior depends on the bonding strategy used.

Six-year clinical evaluation of bulk-fill and nanofill resin composite restorations

OBJECTIVES

This study aims to compare the performance of a bulk-fill and a nanofill resin composite in class II restorations after 6 years.

MATERIALS AND METHODS

Fifty patients having at least two class II carious lesions were recruited for the study. One lesion in each patient was randomly assigned to be restored using either the Tetric EvoCeram Bulk Fill (TB) or Filtek Ultimate (FU) resin composites with their respective adhesives. One hundred four restorations were placed by two calibrated operators. Restorations were evaluated at baseline and annually over the course of 6 years by two examiners using modified USPHS criteria. Data were statistically analyzed using the Chi-square and Cochran Q tests (p < 0.05).

RESULTS

Sixty-six restorations in 33 patients were evaluated after 6 years. Only one restoration was lost from FU group at 5 years. At the end of 6 years, marginal discoloration was observed in three (9.1%) TB and eight (36.4%) FU restorations creating a significant difference between the groups (p < 0.05). The FU group showed a significant increase in marginal discoloration at 6 years from the baseline (p < 0.05). Marginal adaptation was rated as Bravo for 9.1% and 24.2% of TB and FU restorations, respectively (p > 0.05). Significant degradation was observed within each group in terms of marginal adaptation (p < 0.05). There were no statistically significant differences between the groups for the other criteria tested (p > 0.05).

CONCLUSIONS

Bulk-fill restorations performed better for marginal discoloration. The remaining clinical performance criteria of bulk-fill and nanofill resin composite restorations were similar after 6 years.

CLINICAL RELEVANCE

Bulk-fill resin might be a better alternative to incrementally placed restorative in terms of marginal discoloration under clinical conditions.

Microleakage and characteristics of resin-tooth tissues interface of a self-etch and an etch-and-rinse adhesive systems

Objectives

This study was conducted to compare the microleakage and characteristics of the resin-tooth tissue interface between self-etch and etch-and-rinse adhesive systems after 48 hours and 3 months.

Materials and Methods

40 extracted premolar teeth were randomly divided into 2 groups: 1-step self-etch adhesive system – Optibond™ All-In-One, and 2-step etch-and-rinse adhesive system - Adper™ Single Bond 2. Both groups were subjected to 500 thermocycles (5°C–55°C) before scanning electron microscope (SEM) analysis or microleakage trial at 48-hour and 3-month time periods.

Results

SEM images showed the hybrid layer thickness, diameter, and length of resin tags of the self-etch adhesive (0.42 ± 0.14 µm; 1.49 ± 0.45 µm; 16.35 ± 14.26 µm) were smaller than those of the etch-and-rinse adhesive (4.39 ± 1.52 µm; 3.49 ± 1 µm; 52.81 ± 35.81 µm). In dentin, the microleakage scores of the 2 adhesives were not different in both time periods (48 hours/3 months). However, the microleakage score of etch-and-rinse adhesive increased significantly after 3 months (0.8 ± 0.63 and 1.9 ± 0.88, p < 0.05).

Conclusions

The self-etch adhesive exhibited better long-term sealing ability in dentin when compared to that of the etch-and-rinse adhesive. The greater hybrid layer thickness and dimensions of resin tags did not guarantee reliable, long-lasting sealing in the bonding area.

Effects of calcium-containing desensitizers on the bonding stability of an etch-and-rinse adhesive against long-term water storage and pH cycling

This study aimed to evaluate the effects of two calcium-containing desensitizing pastes on the bonding stability of an etch-and-rinse (E&R) adhesive to dentine. After dentine hypersensitivity model established, dentine surfaces were assigned one of the following pretreatment: Group 1, no desensitizer; Group 2, CPP-ACP; and Group 3, Novamin. Specimens were then bonded with an E&R adhesive. Beams from each tooth were randomly divided into three subgroups and then subjected to microtensile bond strength (MTBS) test after 24 h; 12 months of water storage; or 15 runs of pH cycling. Failure modes, nanoleakage, and tubule-occluding effectiveness were analyzed. Results showed that CPP-ACP- or Novamin-pretreated specimens mainly preserved the bonding strength after 12 months of water storage, while effective tubule occlusion could be observed. The results suggested that the calcium-containing desensitizers were compatible pretreatment for bonding with E&R adhesives to obtain reliable long-term bonding strength and prevention of post-operative sensitivity.

Effect of dimethyl sulfoxide on bond durability of fiber posts cemented with etch-and-rinse adhesives

PURPOSE

This study was undertaken to investigate whether use of an adhesive penetration enhancer, dimethyl sulfoxide (DMSO), improves bond stability of fiber posts to root dentin using two two-step etch-and-rinse resin cements.

MATERIALS AND METHODS

Forty human maxillary central incisor roots were randomly divided into 4 groups after endodontic treatment and post space preparation, based on the fiber post/cement used with and without DMSO pretreatment. Acid-etched root dentin was treated with 5% DMSO aqueous solution for 60 seconds or with distilled water (control) prior to the application of Excite DSC/Variolink II or One-Step Plus/Duo-link for post cementation. After micro-slicing the bonded root dentin, push-out bond strength (P-OBS) test was performed immediately or after 1-year of water storage in each group. Data were analyzed using three-way ANOVA and Student's t-test (α=.05).

RESULTS

A significant effect of time, DMSO treatment, and treatment × time interaction were observed (P<.001). DMSO did not affect immediate bonding of the two cements. Aging significantly reduced P-OBS in control groups (P<.001), while in DMSO-treated groups, no difference in P-OBS was observed after aging (P>.05).

CONCLUSION

DMSO-wet bonding might be a beneficial method in preserving the stability of resin-dentin bond strength over time when fiber post is cemented with the tested etch-and-rinse adhesive cements.

Effects of endodontic tri-antibiotic paste on bond strengths of dentin adhesives to coronal dentin

Objectives

The aim of this study was to evaluate the effects of tri-antibiotic paste (TAP) on microtensile bond strengths (MTBS) of dental adhesives to dentin.

Materials and Methods

Sixty extracted molars had their occlusal surfaces flattened to expose dentin. They were divided into two groups, i.e., control group with no dentin treatment and experimental group with dentin treatment with TAP. After 10 days, specimens were bonded using self-etch (Filtek P90 adhesive) or etch-and-rinse (Adper Single Bond Plus) adhesives and restored with composite resin. Teeth were sectioned into beams, and the specimens were subjected to MTBS test. Data were analyzed using two-way ANOVA and post hoc Tukey tests.

Results

There was a statistically significant interaction between dentin treatment and adhesive on MTBS to coronal dentin (p = 0.003). Despite a trend towards worse MTBS being noticed in the experimental groups, TAP application showed no significant effect on MTBS (p = 0.064).

Conclusions

The etch-and-rinse adhesive Adper Single Bond Plus presented higher mean bond strengths than the self-etch adhesive Filtek P90, irrespective of the group. The superior bond performance for Adper Single Bond when compared to Filtek P90 adhesive was confirmed by a fewer number of adhesive failures. The influence of TAP in bond strength is insignificant.

Effects of the application sequence of calcium-containing desensitising pastes during etch-and-rinse adhesive restoration

OBJECTIVES

To evaluate the effects of different application sequence of calcium-containing desensitising pastes on bonding effectiveness and tubule occlusion during etch-and-rinse (E&R) adhesive restoration.

METHODS

Seventy molars were sectioned parallel to the occlusal plane, polished and randomly divided into seven groups (n=10). Group 1 was etched with 35% phosphoric acid for 15s. Groups 2-4 were treated with different calcium-containing desensitisers, including an arginine-calcium carbonate (Arg-CaCO3)-containing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste and a calcium-sodium phosphosilicate (Novamin)-containing paste, respectively. Afterward, these groups were etched with 35% phosphoric acid for 15s. Groups 5-7 were initially etched and then treated with Arg-CaCO3-, CPP-ACP- and Novamin-containing desensitisers, respectively. In each group, samples were equally distributed into two subgroups (n=5) to bond with either a two-step E&R adhesive Adper SingleBond 2 (SB) or a three-step E&R adhesive Adper ScotchBond Multi-Purpose (SBMP). The microtensile bond strengths (MTBS) were tested and fracture modes were analyzed by stereomicroscopy and field-emission scanning electron microscopy (FESEM). Eight additional dentine disks were prepared to evaluate tubule occlusion prior to bonding using FESEM.

RESULTS

The application sequence of calcium-containing desensitising pastes did not significantly affect MTBS irrespective of two-step SB (P>0.05) or three-step SBMP E&R adhesives (P>0.05). Effective dentinal tubule occlusion was observed in the mode of etching-desensitising.

CONCLUSIONS

Applying calcium-containing desensitisers (particularly Arg-CaCO3- and Novamin-based) after etching during E&R adhesive restoration could achieve effective tubule occlusion without affecting the bonding strength.

Cuspal movement related to different bonding techniques using etch-and-rinse and self-etch adhesive systems

OBJECTIVES

To investigate the effects of adhesion technique using different contemporary adhesive systems on the cuspal movement in class II composite restorations in human premolar teeth.

METHODS

Human premolar teeth were prepared with class II cavities and then restored with composite and etch-and-rinse (Adper Scotchbond Multi Purpose and Adper Single Bond) or self-etch (Clearfil SE Bond and Clearfil S3 Bond) adhesive systems under different bonding techniques (total bonding and selective bonding). The influence of an intermediate layer of flowable composite was also evaluated. The cuspal distance was measured before and after the restorative procedure, and the difference was recorded as cuspal movement. The data were submitted to ANOVA test and Tukey's post hoc comparison procedure test (alpha=0.05).

RESULTS

For all adhesive systems, the teeth restored with selective bonding technique showed lower values of cuspal movement and the use of an intermediary layer of flowable composite did not show any influence on the cuspal movement.

CONCLUSIONS

Both the adhesive techniques tested were not able to prevent the cuspal movement. However, selectively bonded class II composite restorations demonstrated lower values of cuspal movement comparing with total bonding technique, and the use of an intermediate layer of flowable composite did not diminish the values of cuspal movement.