Effects of conditioners on microshear bond strength to enamel after carbamide peroxide bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment

Objectives: To evaluate (a) the enamel microshear bond strength (MSBS) of a universal adhesive and (b) the effects of conditioning with a self-etching primer adhesive with/without prior bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application. Methods: Thirty-five molars were cut into four sections, assigned randomly to four groups (no treatment; 16% carbamide peroxide bleaching; CPP-ACP-containing paste (Tooth Mousse, TM); bleaching and TM) and treated accordingly. Specimens were divided into two for bonding with either a self-etching primer (Clearfil SE Bond, CSE) or a total-etch adhesive (Single Bond, SB). Specimens for CSE bonding were subdivided for one of four preconditioning treatments (no conditioning; 30-40% phosphoric acid (PA); 15% EDTA; 20% polyacrylic acid conditioner (Cavity conditioner, CC) and treated. The adhesives were applied and resin composite bonded to the enamel using microtubes (internal diameter 0.75 mm). Bonds were stressed in shear until failure, mean MSBS calculated and data analysed using ANOVA with Tukey's HSD test (α = 0.05). The modes of bond failure were assessed and classified. Results: Two-way ANOVA revealed significant differences between treatments (P < 0.0001), conditioners (P < 0.0001) and a significant interaction between treatments and conditioners (P = 0.001). One-way ANOVA revealed no significant differences in MSBS following any of the treatments for SB; following TM application for CSE without preconditioning; and significant differences in MSBS following bleaching with and without TM application for CSE. With preconditioning, applying PA before CSE post-bleaching and either PA or CC before CSE post-TM application, resulted in significant differences in MSBS (P < 0.05). Conclusions: The use of conditioners prior to bonding with the self-etching primer adhesive system on treated enamel may significantly improve bond strengths. © 2007 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Relationship between composite fracture toughness and bond strengths to enamel and dentine

Scientific articleBackground: This study aimed to evaluate the association between the fracture toughness of two nanofilled-hybrid resin composites (Clearfil Majesty Esthetic [CME], Kuraray Medical, Japan; Estelite Σ [ES], Tokuyama, Japan) and their bond strengths to enamel and dentine mediated by a self-etching primer system (Clearfil SE Bond [CSE]; Kuraray). Methods: Twenty-four permanent human molars were sectioned into enamel and dentine specimens and finished with 600-grit silicon carbide paper, bonded with CSE and either CME or ES, for μ-shear bond strength (μSBS) and μ-tensile bond strength (μTBS). The specimens were tested until failure at a cross-head speed of 1 mm/min, failure loads recorded, bond strengths calculated and results analysed using independent samples t-tests. Eight single-notched bar-shaped specimens, 30 mm × 5.2 mm × 2.2 mm, were prepared for each resin composite and fracture toughness measured using four-point bending at a cross-head speed of 0.5 mm/min. Results were analysed using independent samples t-tests. Results: For μSBS and μTBS, there was no significant difference between the resin composites for enamel or dentine. The fracture toughness of CME was significantly higher than that of ES. Conclusions: For both enamel and dentine, resin composite fracture toughness affected neither μTBS nor μSBS to enamel or dentine. © 2012 Australian Dental Association.link_to_subscribed_fulltex

Dentine bonding after CPP-ACP paste treatment with and without conditioning

Objectives: To evaluate microshear bond strength (MSBS) to dentine following application of a casein phosphopeptide amorphous calcium phosphate paste (Tooth Mousse (TM)), and the effect of smear layer removal before paste application and preconditioning. Methods: Specimens of polished human dentine were divided into two groups: 1, smear layer retained; 2, smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were left untreated and half treated with TM for 60 min daily × 7 days. Each subgroup was divided into three further subgroups for conditioning (Primer only; 30-40% phosphoric acid (PA) + primer; 20% polyacrylic acid (CC) + primer). Two self-etching/priming adhesives (Clearfil SE Bond (CSE) and G-Bond (GB)) were used for bonding resin composite to superficial/deep dentine and after 24 h, stressed in shear until failure. Maximum loads at failure and bond failure modes were recorded. Group means were compared using one-way ANOVA and Tukey's post hoc test at α = 0.05. Results: TM did not significantly affect MSBS in group 1. In group 2, there was a statistically significant increase in MSBS for CSE on deep dentine (P = 0.002) and a reduction for GB (P = 0.013) on superficial dentine. PA conditioning did not significantly affect MSBS for CSE and GB while CC significantly reduced MSBS for GB. Conclusions: TM application did not reduce MSBS for CSE but significantly reduced MSBS for GB when the smear layer was removed before paste treatment. Preconditioning did not improve or worsen dentine MSBS for CSE or GB with/without TM, except when CC was used with GB. © 2008 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Bond strength test: Role of operator skill

Background: Test method, substrate material and operator variability are factors known to affect bond strength test outcomes. The aim of this study was to determine if, with increasing experience, individual operator skill in material handling influenced microshear bond strength outcomes. Methods: This retrospective study used data collected from six preliminary tests carried out successively on enamel microshear bond strength for two adhesives: Clearfil SE Bond (Kuraray) and Adper Single Bond 2 (3M ESPE) by one operator. Mean and median microshear bond strength values, standard deviations and coefficients of variation for each adhesive test group were calculated and assessed. Results: A gradual increase in mean microshear bond strengths, a decrease in standard deviations and coefficients of variation over time for both adhesives and a progressively more uniform distribution of microshear bond strength results recorded in individual test sets was observed. The results suggest an improvement in bonding reliability as experience is gained. Conclusions: Operator skill in material handling appears to play a critical role in determining the outcome of bond strength testing. This same skill is probably relevant when using an adhesive for the first time clinically. It is important that clinicians become familiar with new adhesives in order to achieve optimal outcomes. © 2008 Australian Dental Association.link_to_subscribed_fulltex

An SEM evaluation of conditioned and bonded enamel following carbamide peroxide bleaching and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment

Objectives: The study aimed to evaluate, (a) the surface morphology of acid etched/conditioned enamel following carbamide peroxide bleaching with/without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (Tooth Mousse (MI Paste); GC Corp., Tokyo, Japan) treatment; and b) the nature of the bonded resin-enamel interfaces formed with a self-etching primer adhesive. Methods: Twenty-four human adult molars were each sectioned into four, the specimens divided and treated according to four experimental groups: 1, no treatment; 2, 16% carbamide peroxide bleaching; 3, CPP-ACP paste; 4, bleaching and CPP-ACP paste. A self-etching primer adhesive (Clearfil SE Bond, CSE) was used. The specimens were further divided into four subgroups for etching/conditioning: A, CSE Primer only; B, 30-40% phosphoric acid and CSE primer; C, 15% EDTA and CSE primer; D, 20% polyacrylic acid and CSE primer. Bonded specimens were also prepared. The morphology of the etched/conditioned enamel surfaces and polished resin-enamel interfaces of the bonded specimens were observed by field-emission scanning electron microscopy (FE-SEM). Results: Treatment with CPP-ACP did not inhibit phosphoric acid etching of enamel. Poorly defined enamel etch patterns were observed with the other conditioners in all the groups. The morphology of the bonded resin-enamel interfaces observed on FE-SEM for each acid etching/conditioning subgroup was similar in all the experimental groups, except after bleaching. Resin infiltration into enamel was observed with prior phosphoric acid etching and polyacrylic acid conditioning and was unaffected by experimental group treatments. Conclusions: The use of a CPP-ACP paste with or without prior bleaching did not inhibit enamel etching. Enamel etching/conditioning may help improve bonding efficiency of the self-etching primer adhesive after CPP-ACP treatment. © 2009 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Resin-dentine interfacial morphology following CPP-ACP treatment

Objectives: To evaluate the quality of bonded resin-dentine interfaces produced by two self-etching primer adhesives after casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment, in comparison to untreated dentine. Methods: Thirty-four adult molar teeth were sectioned to obtain dentine with tubule orientations parallel/oblique or perpendicular to the surface. The specimens were divided into 'smear layer' (1A, 1B) and 'no smear layer' groups, after treatment with 15% EDTA (2A, 2B). The specimens were then left either untreated (1A, 2A) or treated (1B, 2B) with CPP-ACP paste (Tooth Mousse, GC Corp.) for 60 min × 7 days. Each treatment group was divided into three subgroups and specimens etched/conditioned (no conditioning; 30-40% phosphoric acid (H3PO4); 20% polyacrylic acid) and bonded with either a 2-step self-etching primer adhesive (Clearfil SE Bond, Kuraray Medical) or an 'all-in-one' adhesive (G-Bond, GC Corp.) and a hybrid resin composite. After 24-h water storage, the bonded specimens were sectioned, polished up to 4000-grit abrasive silicon carbide paper and 0.25-μm diamond paste, prepared for FE-SEM using the acid-base technique, critical point-dried, gold-coated and examined. Bonded and fractured dentine interfaces were also prepared and examined. Results: The 2-step adhesive produced a similar appearance of bonded resin-dentine interface irrespective of smear layer group, treatment or etching/conditioning. After polyacrylic acid conditioning, the 'all-in-one' adhesive exhibited more areas with bond failures. The bond failures were within the hybrid layer and more pronounced following CPP-ACP treatment. Conclusion: The quality of the bonded resin-dentine interface produced after CPP-ACP treatment may depend on the adhesive system used. © 2009 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Effect of tooth surface preparation on the bonding of self-etching primer adhesives.

The aim of this study was to determine the bonding effectiveness of four self-etching primer adhesives after various tooth preparation protocols. Enamel/dentin specimens were prepared from 84 permanent molars, divided into three enamel preparation groups (silicon carbide paper [SiC1; erbium, chromium:yttri-um, scandium, gallium, garnet [Er,Cr:YSGG] laser [EL] and diamond bur [DB]) and five dentin preparation groups (SiC, EL, DB, steel[SB], and ceramic burs [CBs]). In each group,specimens were equally divided into four sub-groups and were bonded using Clearfil SEBond (CSE, Kuraray), Xeno IV (XE, Dentsply),Tokuyama Bond Force (TK, Tokuyama) and Filtek Silorane System Adhesive (FS, 3MESPE), as well as a hybrid resin composite(Clearfil Majesty Esthetic, Kuraray) for CSE,XE, and TK, and Filtek Posterior Restorative(3M ESPE) for FS). After 24 hours of water storage at 370C, microshear bond strength(iSBS) testing was carried out. Data were analyzed using analysis of variance (ANOVA)-Tukey test at a=0.05 and bond failure modes assessed. Representative debonded specimens were prepared and examined under the scanning electron microscope (SEM). All adhesives exhibited no significant differences in 1SBS on enamel and dentin under the clinical cavity preparation protocols, except for TK on den-tin. SEM revealed areas of altered subsurface enamel/dentin following EL ablation.link_to_subscribed_fulltex

Enamel microhardness and bond strengths of self-etching primer adhesives

The aim of this study was to determine the relationship between enamel surface microhardness and microshear bond strength (μSBS). Buccal and lingual mid-coronal enamel sections were prepared from 22 permanent human molars and divided into two groups, each comprising the buccal and lingual enamel from 11 teeth, to analyze two self-etching primer adhesives (Clearfil SE Bond and Tokuyama Bond Force). One-half of each enamel surface was tested using the Vickers hardness test with 10 indentations at 1 N and a 15-s dwell time. A hybrid resin composite was bonded to the other half of the enamel surface with the adhesive system assigned to the group. After 24 h of water storage of specimens at 37o°C, the μSBS test was carried out on a universal testing machine at a crosshead speed of 1 mm min-1 until bond failure occurred. The mean μSBS was regressed on the mean Vickers hardness number (VHN) using a weighted regression analysis in order to explore the relationship between enamel hardness and μSBS. The weights used were the inverse of the variance of the μSBS means. Neither separate correlation analyses for each adhesive nor combined regression analyses showed a significant correlation between the VHN and the μSBS. These results suggest that the μSBS of the self-etch adhesive systems are not influenced by enamel surface microhardness. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci.link_to_subscribed_fulltex