The effect of different sealer removal protocols on the bond strength of AH plus‐contaminated dentine to a bulk‐fill composite

A facile method for rejuvenating the bonding efficacy of root canal sealer-smeared dentine

OBJECTIVES

To examine the efficacy of glycine powder air-polishing on cleaning root canal sealer-smeared dentine.

METHODS

Dentine surfaces were contaminated with a smear of epoxy resin-based sealer or tricalcium silicate-based sealer. The contaminated surfaces were cleaned with saline, 75% ethanol, or air-polishing with glycine powder. Uncontaminated dentine was used as the control. The cleanliness of pulpal floor dentine was examined using scanning electron microscopy and energy dispersive X-ray analysis. The effectiveness of the three cleaning protocols was examined by testing the tensile bond strength of a self-etching adhesive to the decontaminated dentine. Resin infiltration into the dentinal tubules was identified using confocal laser scanning microscopy (CLSM).

RESULTS

Morphological examination and elemental analysis indicated that glycine powder air-polishing was more effective in removing the two sealers. Tensile bond strength of adhesive-bonded dentine was significantly reduced when either sealer was cleaned with saline or ethanol. Conversely, air-polishing restored the adhesive strength of the sealer-smeared dentine to the level of the control. Longer and denser resin tags were identified with CLSM when sealers were removed with air-polishing.

CONCLUSIONS

Air-polishing with glycine powder was effective in cleaning sealer-smeared dentine, as demonstrated by the rejuvenation of the tensile bond strength of a self-etching adhesive to the decontaminated dentine.

CLINICAL SIGNIFICANCE

Glycine powder air-polishing improves the cleanliness of root canal sealer-smeared dentine and rejuvenates adhesive bonding effectiveness.

Effect of cleaning materials on microtensile bond strength of resin composite to primary dentin contaminated with root canal sealers

BACKGROUND

There have been no studies on the bond strength of adhesives with dentin surfaces contaminated with root canal sealers in primary teeth without underlying permanent teeth germs. This study investigated the cleaning materials used for primary tooth dentin contaminated with root canal sealers. The aim was to increase the success rate of root canal treatment in pedodontics clinics and retain the teeth for longer.

METHODS

The occlusal enamel layer was removed, followed by the application of root canal sealers (AH Plus or MTA Fillapex) to the dentin and cleaning using different irrigation solutions (saline, NaOCl, and ethanol). The specimens were restored using a self-etch adhesive and composite. Sticks with a thickness of approximately 1 mm were obtained from each sample, and the bond strengths were measured using a microtensile testing device. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.

RESULTS

The control and AH Plus saline groups had the highest bond strengths. The groups cleaned using ethanol had the lowest bond strengths (p < 0.01).

CONCLUSION

Cleaning the dentin with saline-soaked cotton pellets provided the best bond strengths. Therefore, saline is the most effective material for removing both epoxy resin- and calcium silicate-based root canal sealers from the access cavity.

Influence of Phosphoric Acid Etching on Bond Strength for Calcium Silicate-Based Sealers

INTRODUCTION

This study evaluated the microtensile bond strength of calcium silicate-based sealers and AH Plus depending on the use of phosphoric acid (PA) etching before immediate resin restoration.

METHODS

Exposed dentin surfaces of extracted human third molars were randomly assigned to 3 groups depending on sealer type (AH Plus [Dentsply DeTrey], CeraSeal [Meta Biomed Co.], and EndoSeal MTA [Maruchi]). Half of the samples were treated with PA for 30 seconds, and the other half were cleaned with water. Completely untreated specimens were used as controls. Self-etching adhesive (Clearfil SE Bond, Kuraray) was applied, and composite resin (Tetric N-Ceram, Ivoclar Vivadent) was used to create build-ups. After 24 hours, the microtensile bond strength was measured (EZ Test, Shimadzu Co.). The failure mode was determined by light microscopy and scanning electron microscopy. One-way analysis of variance with the Bonferroni correction was used to analyze the data (p<0.05).

RESULTS

The bond strength of the water-washed dentin surfaces in the calcium silicate-based sealer groups did not differ significantly from those of the control surfaces, but the PA-pretreated surfaces exhibited relatively low bond strength. The AH Plus-treated group had lower bond strength than the control group when no PA treatment was applied, but PA treatment restored the bond strength. The adhesive failure mode was most frequently found in the AH Plus group without PA etching.

CONCLUSIONS

When a water-soluble calcium silicate-based sealer is used, sufficient bond strength can be obtained by washing with water alone, with no need for PA use.

Protocols for cleaning the incisor access cavity contaminated with epoxy resin sealer

This study compared different methods for cleaning the sealer-contaminated access cavity of upper incisors. After standard endodontic access, the canals of 50 extracted maxillary incisors were chemomechanically prepared and obturated with gutta-percha and epoxy resin sealer. Teeth were randomly assigned to one of five different pulp chamber cleaning protocols (n = 10): air/water spray, ethanol-saturated cotton pellet (CP), ethanol-saturated microbrush reaching the root filling (MB), MB + air polishing (PROPHYflex; KaVo), or MB + etching with 37% phosphoric acid. Each tooth was split and the sealer-covered area of the pulp chamber was determined on images taken before and after cleaning using image analysis software. The sealer-covered area was compared across groups using one-way ANOVA. Greatest mean sealer-covered area reduction was observed for MB + etching (98.0%), MB + air polishing (95.2%), and MB alone (92.8%), yielding a significantly higher sealer-covered area reduction than after air/water spray (8.3%) and ethanol-saturated cotton pellet (53.4%). The upper incisor access cavity is best cleaned with an ethanol-saturated microbrush reaching up to the root filling, followed by air/water spraying and etching. The use of cotton pellets should be discouraged.

Microtensile bond strength to sealer-contaminated dentin after using different cleaning protocols

Background/purpose

Sealer residues on dentin may affect bonding to restorative materials. This study aimed to evaluate the bond strength to sealer-contaminated dentin after using different cleaning protocols.

Materials and methods

Freshly extracted bovine incisors were prepared and exposed the buccal pulp chamber dentin, obtaining segments measuring 5 mm × 5 mm with a height of 3 mm. The segments were randomly distributed into 4 groups (n = 7) according to different protocols. Control group: no contamination was performed. In the three experimental groups, the segments were contaminated with epoxy resin-based sealer for 5 min, and different cleaning protocols were performed. Acetone group: acetone-saturated cotton pellets were used to wipe the sealer. Ultrasound group: ultrasonic ET-20D tip cleaning. Acetone combined with ultrasound group: cleaning with acetone-saturated cotton pellets and ultrasonic tip. All segments were bonded using a self-etch adhesive. Two samples in each group were scanned by swept-source optical coherence tomography (SS-OCT) to evaluate sealer residues. A microtensile test was performed on the remaining 5 samples, which were built up with composite resin.

Results

Sealer residues were observed in 3 of 14 (21.4%) sections of acetone group by SS-OCT. Compared to the control, ultrasound alone or in combination with acetone preserved the bond strength (P > .05). The ultrasound group exhibited the highest bond strength (39.38 MPa), which differed from that of the acetone group, which provided the lowest bond strength (32.88 MPa) (P < .05).

Conclusion

Cleaning epoxy resin-based sealer-contaminated dentin surfaces using ultrasound or combined with acetone could preserve the bond strength.

Effects of dentine surface cleaning on bonding of a self-etch adhesive to root canal sealer-contaminated dentine

OBJECTIVES

To compare the effectiveness of different sealer cleaning methods on bonding of a self-etch adhesive to root canal sealer-contaminated dentine.

METHODS

Forty-nine extracted molars were divided into seven groups. Dentine surfaces were exposed and cotaminated with a thin layer of epoxy resin-based sealer (AH Plus (AHP)) or zinc oxide eugenol-based sealer (Pulp Canal Sealer (PCS)). Three cleaning protocols were examined: dry cotton pellet, 70% ethanol-saturated cotton pellet or a surfactant-based cleaner (Katana^TM Cleaner (KC), Kuraray Noritake Dental Inc.). Uncontaminated dentine served as control. The dentine surfaces were bonded with a two-step self-etch adhesive and restored with resin composite. Bond strength testing was performed using a microtensile approach. Two teeth from each group were used for scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The pulpal floor of the teeth was covered with sealer and cleaned. The percentage of zinc/zirconium on the dentine surface was detected to indicate the amount of remnant sealer.

RESULTS

Tensile bond strength for uncontaminated dentine control was 46.4±7.3 MPa; bond strength decreased significantly for the dry cotton group (29.6±4.2 MPa for AHP, 24.7±4.7 MPa for PCS, p<0.05). Both ethanol and KC restored bonding performance after cleaning, with no significant difference from the control. Significantly lower MTBS was observed for the ZOE/ethanol subgroup (38.9±5.1 MPa). Cleaner surfaces and less zinc/zirconium elements were identified by SEM/EDX after cleaning with ethanol or KC.

CONCLUSIONS

Katana^TM Cleaner decontaminates root canal sealer-smeared dentine surfaces effectively and restores the bonding performance of a self-etch adhesive to dentine.

CLINICAL SIGNIFICANCE

The surfactant-based Katana^TM Cleaner, originally designed for cleaning zirconia surfaces prior to adhesive bonding, may be used as for cleaning dentine that has been contaminated with unset root canal sealers after root canal treatment to restore the bonding strength of a self-etch adhesive to sealer-contaminated dentine.