Influence of dentin pretreatment with synthetic hydroxyapatite application on the bond strength of fiber posts luted with 10‐methacryloyloxydecyl dihydrogen phosphate‐containing luting systems

The aim of this in vitro study was evaluate the effect of application of synthetic hydroxyapatite on fiber post bond strength to radicular dentine. Forty, single‐root teeth were endodontically treated and an 8 mm post space was prepared. Specimens were randomly placed in four groups (n = 10 in each) and treated using the following fiber post luting procedures: group 1, 17% EDTA + Panavia SA; group 2, 17% EDTA + Teethmate Desensitizer + Panavia SA; group 3, All‐Bond Universal + Duo‐Link Universal; and group 4, All‐Bond Universal + Teethmate Desensitizer + Duo‐Link Universal. Fiber posts were luted in the post space and light‐cured for 120 s using a light‐emitting diode (LED) lamp. After 7 d of storage at 37°C, the teeth were cut into 1‐mm‐thick slices, which were subjected to a push‐out test until failure using a universal testing machine. Two specimens per group were prepared for scanning electron microscopy analysis. An energy‐dispersive X‐ray spectroscopy detector was used for elemental analysis of the specimen surface. The results were statistically analyzed using one‐way anova . The fiber post bond strength was statistically significantly increased after the application of Teethmate Desensitizer to post space walls, either with a 10‐MDP‐containing self‐adhesive cement or with a universal adhesive. Scanning electron microscopy and EDAX analysis showed that Teethmate Desensitizer created a calcium phosphate precipitate over post space dentinal tubules, which significantly improved the bond strength of the fiber post luted with 10‐methacryloyloxydecyl dihydrogen phosphate (10‐MDP)‐containing adhesive systems.     

Push‐out bond strength of an experimental self‐adhesive resin cement

The adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest over the past years. The aim of this study was to assess the post retentive potential of experimental self‐adhesive resin cement (EXP) when used alone and in combination with a self‐etch adhesive. Fiber posts were placed in endodontically treated teeth and divided into four groups (n = 6) according the luting material, as follows: group 1 (EXP alone); group 2 (EXP used with self‐etch adhesive); group 3 (marketed dual‐cured cement used with self‐etch adhesive); and group 4 (marketed self‐adhesive cement). The push‐out test was used to assess the retentive strength of fiber posts (expressed in MPa), and specimens were analyzed under a stereomicroscope to determine failure mode. The adhesive interface between the cement and root canal dentin for each group was evaluated using scanning electron microscopy. The post retentive potential of group 1 (EXP) (7.48 ± 4.35 MPa) was comparable with that of marketed cements from group 4 (6.79 ± 3.68 MPa) and group 3 (8.77 ± 4.58 MPa). When EXP was used in combination with self‐etch adhesive (group 2), significantly higher push‐out bond‐strength values were measured (15.87 ± 4.68 MPa) compared with the other groups.     

Effect of maleic acid on the bond strength of fibre posts to root dentine

The aim of this study was to evaluate the effect of maleic acid (MA) on both the bond strength of fibre post to root dentine and smear layer removal after post space preparation. Sixty, single‐canal premolars were endodontically treated and randomly assigned to four groups: group 1 [0.9% saline solution (control]); group 2 [2.5% sodium hypochlorite (NaOCl)]; group 3 [17% ethylenediaminetetraacetic acid (EDTA) followed by 2.5% NaOCl]; and group 4 (7% MA followed by 2.5% NaOCl). Self‐adhesive resin cement was used to test the adhesion of a glass‐fibre post to the root dentine through a micropush‐out test. Scanning electron microscopy was performed to examine and score the treated specimens for smear layer removal, and stereomicroscopy was applied to investigate the failure modes of fibre posts. Maleic acid exhibited the highest mean bond‐strength values in the apical regions among all the groups. Most failure modes (31.9%) were adhesive‐type failures between the dentine and luting materials. Maleic acid performed statistically significantly better than the other groups regarding smear layer removal, especially in the apical region. Maleic acid is an effective irrigant that can remove the smear layer, open dentinal tubules, and act as a high‐efficiency final irrigant in activation protocols.     

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

The integrity of composite bonding for post‐endodontic restorations may be compromised by sealer contamination. This study assessed the effect of different sealer removal regimes on the bond strength of dentine to composite resin. Dentine surfaces were contaminated with AH Plus sealer (Dentsply DeTrey, Konstanz, Germany), followed by removal with either dry cotton pellets, cotton pellets saturated with 95% ethanol, AH Plus cleaner or external surface preparation. Dentine surfaces were not contaminated in a positive control group. A bulk‐fill composite (SDR; Dentsply) was bonded with Prime&Bond active universal adhesive (Dentsply) onto the prepared surface. Composite resin–dentine beams were produced, and tensile bond strength was determined using a universal testing machine. Using an etch‐and‐rinse adhesive, bond strengths varied from 21.34 to 29.11 MPa with no statistical differences among removal protocols. In conclusion, contamination by AH Plus sealer does not appear to substantially interfere with bond strength between dentine and a bulk‐fill composite/etch‐and‐rinse system.     

Effect of ethanol application on post-luting to intraradicular dentine

Aim  To examine the effect of the application of an ethanol rinse before luting fibre posts to intraradicular dentine with etch-and-rinse adhesive systems by means of push-out bond strength evaluation and scanning electron microscopic (SEM) analysis.
Methodology  Fibre posts were luted to single-canal premolars using Dual Link as a luting agent in combination with a three-step (All Bond 2) or a two-step (One Step Plus) etch-and-rinse adhesive system, which were applied as per manufacturers' instructions (control) or with the additional rinse of ethanol on acid-etched dentine prior to the bonding procedures (experimental). Bonded specimens were sectioned into 1-mm-thick slabs and subjected to push-out bond strength testing. In addition, specimens from each group were processed for SEM analysis. Data were analysed by Kruskal–Wallis followed by Dunn's post hoc test at P  = 0.05.
Results  Push-out bond strength of All Bond 2 was significantly increased if the adhesive was applied on ethanol-saturated dentine ( P  < 0.05), whilst no significant difference ( P  > 0.05) was detected amongst experimental and control groups for One Step Plus. Irrespective of the adhesive, the SEM analysis revealed good impregnation patterns when both bonding techniques were employed.
Conclusions  The use of the additional ethanol rinse on acid-etched dentine revealed higher bond strength of All Bond 2 when compared with the control application procedure, used in combination with a resin-based cement to lute fibre posts into the dowel space. However, no bond strength improvements were detected using One Step Plus. Further investigations are needed to develop a clinically applicable ethanol/bonding/luting technique.     

Role of preliminary etching for one‐step self‐etch adhesives

Taschner M, Nato F, Mazzoni A, Frankenberger R, Krämer N, Di Lenarda R, Petschelt A, Breschi L. Role of preliminary etching for one‐step self‐etch adhesives.
Eur J Oral Sci 2010; 118: 517–524. © 2010 Eur J Oral Sci The aim of this study was to analyse the effect of preliminary phosphoric acid etching of enamel and dentine before the application of two, one‐step self‐etch adhesive systems. The systems were applied onto acid‐etched or smear‐layer‐covered enamel and dentine. The treatment groups were as follows: group 1, Adper Easy Bond (3M ESPE) on etched substrate; group 2, Adper Easy Bond (control); group 3, iBond Self‐Etch (Heraeus Kulzer) on etched substrate; and group 4, iBond Self‐Etch (control). Enamel and dentine bond strengths were calculated using microshear and microtensile bond‐strength tests. Additional specimens were prepared to evaluate nanoleakage at the dentine–adhesive interface and were investigated using light microscopy or transmission electron microscopy. Both adhesives demonstrated higher microshear bond strengths when enamel was pre‐acid‐etched with phosphoric acid (Adper Easy Bond 28.7 ± 4.8 MPa; iBond Self‐Etch 19.7 ± 3.6 MPa) compared with controls (Adper Easy Bond 19.2 ± 3.3 MPa; iBond Self‐Etch 17.5 ± 2.7 MPa) and increased microtensile bond strength when applied on acid‐etched (Adper Easy Bond 35.8 ± 5.7 MPa; iBond Self‐Etch 24.3 ± 7.9 MPa) vs. smear‐layer‐covered dentine (Adper Easy Bond 26.9 ± 6.2 MPa; iBond Self‐Etch 17.6 ± 4.3 MPa). Adper Easy Bond showed lower nanoleakage than iBond Self‐Etch, irrespective of preliminary etching. The results of this study support the use of phosphoric acid etching before the application of one‐step self‐etch adhesive systems.     

Various irrigation protocols for final rinse to improve bond strengths of fiber posts inside the root canal

Irrigation after post space preparation and its effects on the bond strength of different adhesive strategies are still an issue of interest. The aim of the present study was to investigate the effects of various irrigation protocols (IPs) on the push‐out bond strengths of fiber posts. One‐hundred and fifty extracted human anterior teeth were divided into three groups (n = 50 each) and endodontically treated. The post space was irrigated before post placement using the following five IPs in each group: IP1 (control): 5 ml of distilled water; IP2: 5.25% sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation (PUI); IP3: 1% NaOCl applied with PUI; IP4: 18% ethylenediaminetetracetic acid (EDTA) followed by 5.25% NaOCl; and IP5: 2% chlorhexidine (CHX). Fiber posts placement in each group was performed using three different adhesive strategies. A self‐etch adhesive system revealed higher bond strength (16.2 ± 6.9 MPa) compared with an etch‐and‐rinse adhesive (8.5 ± 4.2 MPa) and a self‐adhesive resin cement (9.2 ± 4.7 MPa). The use of 18% EDTA/5.25% NaOCl increased the bond strength of the self‐adhesive resin cement. Conversely, this IP decreased the bond strength for the etch‐and‐rinse adhesive system, whilst 1% NaOCl enhanced the bond strength for the same system. Consequently, each adhesive strategy may need to be adapted to a specific IP.     

MORPHOLOGICAL ANALYSIS OF GLASS,CARBON AND GLASS/CARBON FIBER POSTS AND BONDING TO SELF OR DUAL-CURED RESIN LUTING AGENTS

Objective:

The aim of this study was to evaluate the morphology of glass (GF), carbon (CF) and glass/carbon (G/CF) fiber posts and their bond strength to self or dual-cured resin luting agents.

Material and Methods:

Morphological analysis of each post type was conducted under scanning electron microscopy (SEM). Bond strength was evaluated by microtensile test after bisecting the posts and re-bonding the two halves with the luting agents. Data were subjected to two-way ANOVA and Tukey''s test (α=0.05). Failure modes were evaluated under optical microscopy and SEM.

Results:

GF presented wider fibers and higher amount of matrix than CF, and G/CF presented carbon fibers surrounded by glass fibers, and both involved by matrix. For CF and GF, the dual-cured material presented significantly higher (p<0.05) bond strength than the self-cured agent. For the dual agent, CF presented similar bond strength to GF (p>0.05), but higher than that of G/CF (p<0.05). For the self-cured agent, no significant differences (p>0.05) were detected, irrespective of the post type. For GF and G/CF, all failures were considered mixed, while a predominance of adhesive failures was detected for CF.

Conclusion:

The bonding between fiber posts and luting agents was affected by the type of fibers and polymerization mode of the cement. When no surface treatment of the post is performed, the bonding between glass fiber post and dual-cured agent seems to be more reliable.     

Effect of EDTA conditioning upon the retention of fibre posts luted with resin cements

Aim To determine if a final rinse with EDTA improves the short‐term in‐tooth retentive strength of adhesively luted fibre‐reinforced composite posts. Methodology Six different commercial fibre post systems were tested. Post spaces in extracted human anterior teeth were irrigated with either 6% NaOCl or 6% NaOCl followed by 17% EDTA. Posts were luted using the manufacturer’s recommended bonding agent and luting cement. Two different sizes of post were tested for each post system. After 24 h of storage, the retentive strength of the post to the tooth (14 per group, 336 total) was tested using a pull‐out technique. Three‐way anova and the Student–Newman–Kuels test were used to test the effects of irrigation regimen, post size and post brand on the retentive strength of the fibre post. Results Almost every sample failed at the interface between dentine and luting cement. Irrigation method did not have any significant effect (P > 0.14) for any group other than ParaPost Fibre White (P < 0.001). The overall retention of a post appeared to be correlated to the amount of surface texture on the post; the smooth ICEPost was the least retentive brand, the textured FibreKor and the ParaPost Fibre White posts were moderately retained, and the threaded Flexi‐Post Fibre and the Flexi‐Flange Fibre posts were the most retentive brands tested. For all brands, larger diameter posts were more retentive than smaller diameter posts (P < 0.008). Conclusions A final rinse of EDTA did not improve the short‐term retention of fibre posts except for ParaPost Fibre White.     

Flexural strength of glass fibre‐reinforced posts bonded to dual‐cure composite resin cements

Davis P, Melo LSD, Foxton RM, Sherriff M, Pilecki P, Mannocci F, Watson TF. Flexural strength of glass fibre‐reinforced posts bonded to dual‐cure composite resin cements. Eur J Oral Sci 2010; 118: 197–201. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The aims of this study were to evaluate the flexural strength of two different types of glass fibre‐reinforced posts bonded to dual‐cure composite resin cements. Forty glass methacrylate‐based fibre posts (GC Fiber Post) and 20 glass fibre inter‐polymerizing network posts (everStick POST) were divided into three groups. Group 1 contained 20 GC posts that were bonded to a dual‐cure composite cement (UnifilCore). Group 2 contained 20 Stick Tech posts that had adhesive applied (Scotchbond Multipurpose resin) and were bonded to a dual‐cure composite resin cement (RelyX Unicem). Group 3 contained 20 GC posts that were pretreated with a silane‐coupling agent before being treated with resin and composite, as in group 1. A 4‐point bend test was carried out to failure on all of the groups. Failure modes were determined using scanning electron microscopy. Pretreatment of the post surface with the silane‐coupling agent did not increase the flexural strength. The flexural strength of the Stick Tech post was significantly lower than the flexural strength of the GC post. The mode of failure for the GC Posts was adhesive, whereas the Stick Tech posts failed cohesively. Different flexural strengths and failure modes were observed among the two fibre post–resin systems.     

Effect of post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts

The aim of this study was to evaluate the effect of different post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push‐out test. Data were statistically analysed with anova (P = 0.05). After push‐out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.     

The effect of repeated fluoride recharge and storage media on bond durability of fluoride rechargeable Giomer bonding agent

Background:  For a restorative material or adhesive to exhibit caries inhibitive potential through fluoride release, it must be capable of fluoride recharge. The aim of this study was to evaluate the effect of repeated fluoride recharge and different storage media on dentine bond strength durability. Methods:  Two self‐etch adhesive systems (two‐step) were evaluated: fluoride‐rechargeable Giomer FL‐Bond II and non‐fluoride‐containing UniFil Bond. For each adhesive 32 human dentine specimens were prepared for shear bond strength testing. The specimens were randomly allocated to one of four storage groups: Group 1 – 24‐hour water ageing; Group 2 – four‐month water ageing; Group 3 – four‐month water ageing with weekly fluoride recharge (5000 ppm for 10 minutes); and Group 4 – four‐month acid ageing with weekly fluoride recharge. Results:  Weekly fluoride recharge over four months ageing did not significantly (p > 0.05) reduce the dentine shear bond strength of FL‐Bond II or UniFil Bond. Storage media did not significantly (p > 0.05) affect bond durability. Conclusions:  The adhesion between fluoride rechargeable FL‐Bond II and dentine maintained durability despite regular fluoride recharge over the four months ageing. Clinicians prescribing the fluoride recharge regime used in the present study to reduce recurrent caries incidence associated with Giomer FL‐Bond II restorations can do so without compromising dentine bond strengths.     

表面处理及不同水门汀材料对纤维桩粘固性能影响的研究

目的：评价酸蚀一喷砂处理以及4种不同水门汀材料Fuji I（FUI）、Fuji Cem（FUC）、RelyX Unicem（RX—U）、RelyXARC（RXA））对纤维桩粘固性能的影响。方法：选取80颗无龋坏单根管人前磨牙,根据对应纤维桩表面处理与否随机分为2组,进而根据粘接材料的不同分为4个亚组。常规根管充填和桩道预备后,分别选用4种水门汀材料将表面处理前后的玻璃纤维桩粘接到预备根管内;观察纤维桩表面及每组试件粘接界面扫描电镜（SEM）下微观形貌,测试即刻拉出强度（pull—outtest）。结果：表面处理前后纤维桩的各水门汀材料拉出强度以RXA组最高,随后依次为RXU、FUC、FUI组,且各组间均相差显著（P〈0．05）;纤维桩表面处理后与各水门汀材料的拉出强度较之处理前均显著提高（P〈0．05）：SEM观察显示：表面处理后纤维桩的表面粗糙度纤维暴露数量均有明显增加;表面处理前后各组粘接界面微观形貌存在差异,各组的粘接界面均较处理前更致密。结论：酸蚀一喷砂处理纤维桩表面后可以提高其与不同水门汀材料的粘接固位力。     

Fiber‐post bond strength in canals obturated with a cross‐linked gutta‐percha core obturator

The aim of this in‐vitro study was to evaluate the bond strength of fiber posts cemented in a root canal filled using various root‐canal obturation techniques. A total of 33 monoradicular samples, treated endodontically, were randomly assigned to three groups according to the root‐canal obturation technique: group 1, continuous‐wave technique; group 2, plastic‐obturator‐core technique; and group 3, cross‐linked gutta‐percha obturator‐core technique. Fiber posts were luted in each sample and each was sectioned perpendicular to the post axis. The push‐out test was performed using a universal machine and the maximum failure load was recorded in MPa mm^?2. Several samples were randomly chosen for scanning electron microscopy evaluation. The mean debris and dentinal tubule‐opening scores were calculated separately in the coronal and apical portions. Bond strength was significantly higher in group 1 than in groups 2 and 3. Debris scores were significantly higher in the apical portion of groups 2 and 3 than in group 1. Within the limitations of this study it can be affirmed that thermoplasticized alpha gutta‐percha seemed to worsen the cleaning of post‐space walls and hence reduced fiber‐post bond strength.     

Influence of ageing on self‐etch adhesives: one‐step vs. two‐step systems

The aim of this study was to evaluate microtensile bond strength (μTBS) to dentine, interfacial nanoleakage expression, and stability after ageing, of two‐step vs. one‐step self‐etch adhesives. Human molars were cut to expose middle/deep dentine, assigned to groups (n = 15), and treated with the following bonding systems: (i) Optibond XTR (a two‐step self‐etch adhesive; Kerr), (ii) Clearfil SE Bond (a two‐step self‐etch adhesive; Kuraray), (iii) Adper Easy Bond (a one‐step self‐etch adhesive; 3M ESPE), and (iv) Bond Force (a one‐step self‐etch adhesive; Tokuyama). Specimens were processed for μTBS testing after 24 h, 6 months, or 1 yr of storage in artificial saliva at 37°C. Nanoleakage expression was examined in similarly processed additional specimens. At baseline the μTBS results ranked in the following order: Adper Easy Bond = Optibond XTR ≥Clearfil SE = Bond Force, and interfacial nanoleakage analysis showed Clearfil SE Bond = Adper Easy Bond = Optibond XTR> Bond Force. After 1 yr of storage, Optibond XTR, Clearfil SE Bond, and Adper Easy Bond showed higher μTBS and lower interfacial nanoleakage expression compared with Bond Force. In conclusion, immediate bond strength, nanoleakage expression, and stability over time were not related to the number of steps of the bonding systems, but to their chemical formulations.     

Effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin

This study evaluated the effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin. Bovine roots were endodontically treated, and 10 roots were used for each adhesive application mode: PB (Prime&Bond 2.1), PB + SC (Self-cure activator), PB + SBM (Scotchbond Multi-purpose adhesive system), BB (Brush&Bond), BB + CAT (chemical catalyst), and BB + SBM. The translucent Light-Post and Aestheti-Post were cemented. The roots/cemented posts were transversally sectioned to originate three thirds (cervical, middle, and apical). The push-out test was performed, and the failure mode of fractured specimens was analyzed. There was no difference between the fiber posts. For PB and BB, the use of hydrophobic adhesive resin SBM increased post bond strength. The use of SC and CAT catalyst did not affect the push-out bond strength values. The apical third presented the lowest bond strengths.     

Bond strength of fibre glass and carbon fibre posts to the root canal walls using different resin cements

The aim of the study was to evaluate the bond strength of fibre glass and carbon fibre posts in the root canal walls cemented with self-adhesive (RelyX-Unicem) and chemical (Cement-Post) resin cements. Forty maxillary canines were divided into four groups according to the cement and post used and submitted to the push-out test (0.5 mm min(-1)). The data were submitted to statistical analysis (2-way ANOVA, Bonferroni--P<0.05) and fracture analysis by Scanning Electronic Microscopy. Fibre glass presented the best results when cemented with RelyX-Unicem and Cement-Post (P<0.05). RelyX-Unicem presented the highest bond strength values for both posts (P<0.05). Fracture analysis showed predominance of cohesive fracture of post for RelyX-Unicem and adhesive fracture between dentin/cement and mixed for Cement-Post. The bond strength values were significantly affected by the type of post and cement used and the highest values were found for fibre glass posts and RelyX-Unicem.     

Influence of endodontic sealer cement on fibreglass post bond strength to root dentine

Aim To test the hypothesis that the composition of endodontic sealer cements and the time elapsed between root filling and fibreglass post fixation interferes with adhesion to root canal dentine. Methodology Sixty bovine incisor roots were divided into five groups (n = 12): CI, unfilled; SI, filled with a calcium hydroxide‐based cement‐Sealer 26, and immediate post fixation; S7, Sealer 26 and post fixation after 7 days; EI, filled with a zinc oxide and eugenol‐based cement‐Endofill and immediate fixation; and E7 Endofill and post fixation after 7 days. The posts were cemented with adhesive system and dual resin cement. Ten roots were cross‐sectioned to obtain two 1‐mm‐thick discs for each cervical (TC), middle (TM) and apical (TA) third of the prepared root portion. The posts were submitted to a micropush‐out test. The other two teeth were evaluated using scanning electron microscopy to analyse the bond interface. Data were analysed using anova , Tukey and Dunnett tests (P < 0.05). Results Group EI was associated with a significant reduction in bond strength values irrespective of the root region; TC = 3.50 MPa (P = 0.0001); TM = 2.22 MPa (P = 0.0043) and TA = 1.45 MPa (P = 0.003). Region of canal had an influence on the values for the cement used in group E7, in which only the TA presented differences from the CI. Conclusions Endofill interfered negatively with the bond to root dentine along its full length and in the TA when post fixation was delayed for 7 days. Bond strength decreased from crown to apex in all groups.     

Adhesion to Er:YAG laser and bur prepared root and crown dentine

Background: The purpose of this study was to evaluate the bond strengths between dentine and resin composite obtained after Er:YAG laser treatment of crown or root dentine used together with self‐etch and total‐etch adhesive systems. Methods: One etch‐and‐rinse adhesive (Single Bond, 3M, USA) and one self‐etch system (Clearfil SE Bond, Kuraray, Japan) were applied to root and crown dentine prepared with a regular bur in a turbine or with an Er:YAG laser. The shear bond strength was determined after thermocycling and statistically analysed using independent t‐tests. Results: Crown sites bonded using Clearfil SE Bond and Single Bond adhesives yielded bond strengths similar to that of root dentine sites (p > 0.05). Clearfil SE Bond was stronger in both the lased and non‐lased groups (p < 0.05). The lowest bond strength was obtained when Single Bond without acid etching was used on Er:YAG ablated dentine. When total‐etch adhesive was used, there were significant differences (p < 0.05) between the laser‐ablated and laser‐ablated/acid‐etched and bur‐cut/acid‐etched groups. Conclusions: Er:YAG laser irradiation of root and crown dentine conducted prior to the adhesive protocol adversely affected adhesion and decreased bond strength compared with traditional preparation.     

Thin and thick layers of resin‐based sealer cement bonded to root dentine compared: Adhesive behaviour

This study aims to evaluate tensile and shear bond strengths of one epoxy (AH) and two methacrylate resin‐based sealers (EZ and RS) in thin and thick layers bonded to root dentine. An alignment device was prepared for accurate positioning of 20 root dentine cylinders in a predefined gap of 0.1 or 1 mm. Sealer was placed in the interface. Bond strength tests were conducted. Mode of failures and representative surfaces were evaluated. Data were analysed using anova and post‐hoc tests, with P < 0.05. The thick layer of sealer produced higher bond strength, except for the shear bond strength of EZ. Significant differences between thin and thick layers were found only in tensile bond strengths of AH and RS. Mixed type of failure was constantly found with all sealers. Bond strengths of thick layers of resin‐based sealers to root dentine tended to be higher than with thin layers.