Effect of temporary cements on the microtensile bond strength of self-etching and self-adhesive resin cement

Objective. The aim of this study was to evaluate the microtensile bond strength (µTBS) of self-etching and self-adhesive resin cement systems to dentin affected by the presence of remnants of either eugenol-containing or eugenol-free temporary cements. Materials and methods. Thirty extracted teeth were obtained and a flat dentin surface was exposed on each tooth. Acrylic blocks were fabricated and cemented either with one of two temporary cements, one zinc oxide eugenol (ZOE) and one eugenol free (ZOE-free), or without cement (control). After cementation, specimens were stored in water at 37°C for 1 week. The restorations and remnants of temporary cements were removed and dentin surfaces were cleaned with pumice. Resin composite blocks were cemented to the bonded dentin surfaces with one of two resin cements, either self-etching (Panavia F 2.0) or self-adhesive (RelyX U-100). After 24 h, the specimens were sectioned to obtain beams for submission to µTBS. The fracture mode was evaluated under a stereoscopic loupe and a scanning electron microscope (SEM). Data from µTBS were submitted to two-way repeated-measure ANOVA and the Tukey test (alpha = 0.05). Results. The cross-product interaction was statistically significant (p < 0.0003). The presence of temporary cements reduced the bond strength to Panavia self-etching resin cements only (p < 0.05). Fracture occurred predominantly at the dentin–adhesive interface. Conclusions. The presence of eugenol-containing temporary cements did not interfere in the bond strength to dentin of self-adhesive resin cements.     

Selective masking for thin indirect restorations: can the use of opaque resin affect the dentine bond strength of immediately sealed preparations?

Purpose

Evaluate the dentine bond strength using different methods of application of opaque resins to mask dentine discoloration.

Materials and methods

Dentine was exposed on 21 extracted molars which were assigned to 3 groups: G1: immediate dentine sealing (IDS). G2: IDS + opaque. G3: IDS with adhesive resin mixed with opaque. After 1 week, teeth were restored and beams were fabricated for microtensile testing. Optical microscopy was used to analyse the failure mode.

Results

Bond strength mean values were statistically different: G1 55.20 MPa > G2 45.79 MPa > G3 18.96 MPa. Failure modes were mostly adhesive for G1 and G3. G2 presented mostly mixed failures.

Conclusion

The use of opaque resin to mask discoloured dentine results in a decrease of bond strength.     

Influence of eugenol-containing temporary cement on bonding of self-etching adhesives to dentin

PURPOSE: To investigate the influence of eugenol-containing temporary cement on bonding of resin composite to dentin mediated by self-etching adhesives. MATERIALS AND METHODS: Flat dentin surfaces were produced by grinding of extracted human molars. The dentin surfaces were either used directly or after a one-week exposure to a zinc oxide-eugenol cement (IRM). A resin composite (Herculite XRV) was bonded to the dentin surfaces following treatment with 1 of 6 self-etching adhesives (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, iBond, OptiBond Solo Plus - Self-Etch Adhesive System, and Xeno III). An adhesive system containing 0.5 M EDTA as dentin conditioner (Gluma Classic) was included as negative control, and an etch-and-rinse adhesive system (OptiBond FL) was included as positive control. After storage in water at 37 degrees C for 1 week, the bonded specimens were fractured in shear (n = 8 in each group). RESULTS: Previous contact of dentin with zinc oxide-eugenol cement significantly decreased the bond strength mediated by the negative control and did not affect the bond strength mediated by the positive control. For the self-etching adhesives, no effect was found of previous contact with zinc oxide-eugenol cement. With and without previous contact with zinc oxide-eugenol cement, the etch-and-rinse adhesive system yielded a significantly higher bond strength than all other adhesive systems. CONCLUSION: Previous contact with zinc oxide-eugenol cement did not decrease the bond strength of resin composite to dentin mediated by self-etching adhesives. This finding suggests that eugenol-containing temporary cements may be safe to use in combination with self-etching adhesives.     

A new use for self-etching resin adhesives: Cementing bone fragments

Objectives

To evaluate the bond capacities of four self-etching resin cements and the self-etching adhesives of the same manufacturer when used to cement bone fragments and compare them with a well-known N-butyl-2-cyanoacrylate bone adhesive.

Methods

125 cylindrical bone specimens from pig mandibular ramus bone were prepared using terphane burs and cemented to the corticals of 125 other specimens obtained from pig mandibular body bone using the following bond systems: Group A: Adper PLP/Relyx; group B: Optibond/Maxcem; group C: Hystoacryl; group D: AdheSE/Multilink; group E: G-Bond/G-Cem. Shear bond strength was measured 15 min after cement application using a universal testing machine.

Results

Shear bond strength results: group A 2.54 ± 0.23 MPa; group B 4.83 ± 0.4 MPa; group C 2.90 ± 0.24 MPa; group D 2.10 ± 0.17 MPa; group E 4.22 ± 0.24 MPa. Values for shear bond strength were significantly greater for group B and E compared to groups A, C and D (p < 0.005, test Mann–Whitney). SEM images showed the presence of a hybrid layer similar to that formed by these bond systems when used on dentine.

Conclusion

Within the limitations of an in vitro investigation, results show that self-etching resin cements together with self-etching adhesives may be used for cementing bone fragments.     

Morphological and microtensile bond strength evaluation of three adhesive systems to caries-affected human dentine with chemomechanical caries removal

Objectives

To evaluate the influence of chemomechanical caries removal on bond strengths of three adhesive systems to caries-affected human dentine.

Methods

45 extracted human third molars with occlusal moderate caries were used. One half of each cavity was prepared with chemomechanical method and the other half with bur as the control. Three adhesive systems, Prime&Bond NT (Dentsply, Germany) without any previous conditioning, an etch-and-rinse adhesive (One-Step, Bisco, USA) and a self-etching adhesive (Adper Prompt-L-Pop, 3M ESPE, USA), were applied. The compomer or resin crowns were, then, built up. The prepared specimens were sectioned for scanning electron microscopy (SEM) examination and microtensile bond strength (MTBS) testing. Data were analysed using two-way ANOVA with subsequent application of Student-Newman-Keuls test at p < 0.05.

Results

Opened dentinal tubules and less smear layer were visible by SEM after chemomechanical caries removal, whilst an obvious smear layer covering the dentine surface with occluded tubules was exhibited after bur excavation. Resin tags were seen only in specimens with chemomechanical excavation when Prime&Bond NT system was applied. Statistical analysis of the values of MTBS failed to show significant difference between caries removal methods. However, the values of MTBS for One-Step system achieved with two caries removal methods were both significant higher than other adhesive systems.

Conclusions

Chemomechanical caries removal did not influence the bond strengths of the adhesive systems used in this study to caries-affected human dentine. Highest bond strength was achieved with application of etch-and-rinse adhesive system.     

Effects of C-factor and resin volume on the bonding to root canal with and without fibre post insertion

Objectives

The aim of this study was to evaluate the effects of C-factor and resin volume on the regional bond strength of dual-cure luting resin to root canal dentine.

Methods

Twelve single-root human premolars were decoronated and post space prepared to a depth of 8 mm, with a diameter of 1.5 mm for six roots and 1.75 mm for the other six. Root canal dentine was treated with a dual-cure bonding system and light-cured for 20 s. Specimens were filled with a dual-cure resin composite with or without insertion of 1.4-mm-diameter light-transmitting glass fibre posts, followed by light-curing for 60 s from the coronal direction. After 24 h water storage, each specimen was serially sliced into eight 0.6 mm × 0.6 mm thick beams for a microtensile bond strength test. Failure modes were observed using SEM. Bond strength data were divided into coronal and apical regions and statistically analysed.

Results

For both sizes of post space, bond strengths dramatically decreased when fibre posts were inserted. There were no significant differences in microtensile bond strength between 1.5 mm and 1.75 mm canal width, regardless of fibre post insertion. Regional differences in bond strength were found only in the resin-filled canals.

Conclusions

: The increase of C-factor of the root canal system by insertion of a fibre post had a detrimental effect on the bond strength to root canal dentine. On the other hand, the change of resin volume had no significant effect on bonding.     

Effect of temporary cements on the bond strength of ceramic luted to dentin.

OBJECTIVES: The purpose of this study was to evaluate the effect of either eugenol-containing or eugenol-free temporary cement removal by excavator or sandblasting on the shear bond strength of ceramic luted to dentin. METHODS: A self-etching primer system, Panavia F 2.0, Kuraray Medical (PF2), and a total-etch bonding system, Excite/Variolink II, Vivadent (EXV), were used. One hundred and forty human molars, ground to expose dentin surfaces, were divided into 14 groups (seven groups for each adhesive system). For each adhesive system, either a eugenol-containing (Temp bond) or a eugenol-free (Temp bond NE) temporary cement was applied to the dentin surface for 7 days, then removed by an excavator or sandblasting (four groups). Three control groups were studied where fresh dentin was either scratched by excavator or sandblasted, or underwent no surface treatment. After application of the adhesives, ceramic cones (Cerafil inserts) were adhesively luted to standardized dentin areas. After 24 h storage in distilled water, the shear bond strengths were determined at a cross-head speed of 0.75 mm/min. RESULTS: For each adhesive system, neither the method of temporary cement removal nor the type of temporary cement affected the bond strength significantly (P相似文献   

Influence of drying time and temperature on bond strength of contemporary adhesives to dentine

Objectives

To evaluate the bond strength (μTBS) of self-etching adhesives in different solvent evaporation conditions.

Methods

Flat dentine surfaces from extracted human third molars were bonded with: (1) 2 two-steps self-etching adhesives (Clearfil SE Bond—CSEB); (Protect Bond—PB) and (2) 2 one-step self-etch systems (Adper Prompt L Pop—ADPLP); (Xeno III—XIII). Bonded dentine surfaces were air-dried for 5 s, 20 s, 30 s or 40 s at either 21 °C or 38 °C. Composite build-ups were constructed incrementally. After storage in water for 24 h at 37 °C, the specimens were prepared for microtensile bond strength testing. Data were analyzed by two-way ANOVA and Student–Newman–Keuls at α = 0.05.

Results

CSEB and PB performed better at warm temperature with only 20 s of air-blowing. The bond strength increased when XIII was performed at warm temperature at 40 s air-blowing. Extended air-blowing not affect the performance of ADPLP, except at 30 s air-blowing time at warm temperature.

Conclusions

The use of a warm air-dry stream seems to be a clinical tool to improve the bond strength to self-etching adhesives.     

ElectroBond application may improve wetting characteristics of etched dentine

Objective

To assess the efficacy of an electrically assisted application technique on dentine wettability (water contact angle measurements) and to determine the promoted surface roughness of dentine after applying 37% phosphoric acid etching, a self-etching primer or a self-etching adhesive system.

Methods

Wettability was assessed on 30 caries-free extracted human third molars. Specimens were sectioned parallel to the occlusal surface to expose moderately deep dentine and ground flat (water-wet 180-grit SiC) to provide uniform flat surfaces. 37% H₃PO₄, Clearfil SE Bond (CSEB) primer or Prompt-L-Pop (PLP) adhesive system were applied on dentine surfaces. In half of the specimens, the electric impulse-assisted application technique/ElectroBond-assisted application was followed. Contact angle measurements were performed to assess wettability using the Axisymmetric Drop Shape Analysis technique. Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Two-way ANOVA, Student's t and Student-Newman-Keuls tests were performed (P < 0.05).

Results

PLP-treated dentine showed the highest intertubular roughness and the lowest dentine wettability. ElectroBond application reduced water contact angles when dentine was treated with H₃PO₄ or Clearfil SE Bond primer, but not when dentine was treated with PLP.

Conclusions

The use of electric current improved wettability of dentine surface following application of phosphoric acid and a mild self-etch primer, but not self-etch adhesive.     

Effect of provisional cements on the bond strength of various adhesive bonding systems on dentine

summary Temporization of prepared teeth is needed for protection of the pulp and the restoration of the patients'aesthetic and functional needs. When zinc-oxyphosphate cement is used, eugenol-containing provisional cements are preferred because of their sedative effect to the pulp and because of their acceptable compressive strength. However, prior to definitive adhesive cementation with composite luting resins and dentine bonding agents the use of eugenol-containing provisional cements has to be considered critical because eugenol severely disturbs the polymerization of resinous materials. The purpose of this study was to compare shear bond strength values of various adhesive luting systems on dentine which had been in contact with various provisional cements prior to dentine bonding. The results show that the provisional cements which were used considerably decreased some of the bond strength values of the dentine bonding systems tested. Freegenol® and Fermit®, however, seem to have beneficial effects on the SBS values of Syntac® and ART Bond®. The only bonding system which produces acceptably high average SBS values with a eugenol-containing provisional cement was P-Bond®.     

Effect of 'Try-in' paste removal method on bond strength to lithium disilicate ceramic

Objectives

The aim of this study was to evaluate four methods of Try-in paste removal from a lithium disilicate ceramic surface before cementation and assess the influence on bond strength to a resin luting cement.

Methods

Slices of dentine (1.6 mm thick) were sectioned from the crown of human third molars and truncated cone shape cavities were made with diamond burs. IPS e.max Press ceramic blocks were obtained for each cavity, etched with hydrofluoric acid and fixed with temporary paste, except for Group G1, which was cemented according to the manufacturer's instructions. Try-in paste was removed from the experimental groups using different techniques: G2, ultrasonic bath in distilled water (5 min); G3, air/water spray (1 min); G4, etched with phosphoric acid (2 min) + air/water spray (30 s) and G5, etched with phosphoric acid before and after hydrofluoric acid application + air/water spray (30 s). The ceramic restorations were cemented with the same procedures as G1. Push-out bond strength testing (MPa) was performed in a universal testing machine with a crosshead speed of 0.5 mm/min.

Results

One way ANOVA and Tukey's test (P < 0.05) were applied: G4(19.21)a, G2(17.09)ab, G1(16.82)ab, G3(16.18)ab and G5(15.9)b. The results showed that all of the experimental groups showed remaining particles of Try-in paste. The bond strength in G4 was statistically higher than in G5. No significant difference was shown in the other groups. There was a predominance of adhesive failures between resin cements and ceramics in G5.

Conclusion

The techniques used were not totally effective at removing the Try-in paste; however, the presence of remaining material did not influence the bond strength of restorations. The methods of temporary paste removal may affect the bond strength of ceramic restorations.     

Effect of chlorhexidine incorporation into a self-etching primer on dentine bond strength of a luting cement

Objectives

This study investigated the effect of incorporating chlorhexidine in a self-etching primer on the bond strength of an adhesive resin cement to dentine and on antibacterial activity.

Methods

Experimental self-etching primers were prepared by adding chlorhexidine (CHX) diacetate to ED primer 2.0 (Kuraray Medical Inc.) to obtain chlorhexidine concentrations of 1.0 wt% and 2.0 wt%. Human occlusal dentine surfaces were conditioned for 30 s using the experimental primers or pure ED primer. Composite blocks were luted using Panavia F 2.0 (Kuraray Medical Inc.). After storage in water for 24 h, the bonded teeth were sectioned into 0.9 mm × 0.9 mm beams and stressed to failure in tension to examine microtensile bond strength (μTBS). Fractured surfaces were examined with a field-emission scanning electron microscopy (FE-SEM). The morphology of dentine surfaces that were conditioned with each primer was also observed under FE-SEM. An agar diffusion test was performed to examine the antibacterial effect of each primer against Streptococcus mutans and Enterococcus faecalis.

Results

Addition of chlorhexidine to the primer had significant effects (p < 0.001) on μTBS and antibacterial effect. No significant difference in μTBS was found between the groups that contained 0% and 1% chlorhexidine in the primer (p = 0.095). Conversely, the group that contained 2% chlorhexidine showed significantly lower μTBS and pronounced cohesive failures within the thin layer of the primer.

Conclusions

Incorporation of chlorhexidine into ED primer 2.0 showed significant antibacterial activities. Conditioning with the 1% chlorhexidine-containing primer had no adverse effect on μTBS.     

Correlation between microtensile bond strength data and clinical outcome of Class V restorations

Objective

To determine if the results of resin-dentin microtensile bond strength (μTBS) is correlated with the outcome parameters of clinical studies on non-retentive Class V restorations.

Methods

Resin-dentin μTBS data were obtained from one test center; the in vitro tests were all performed by the same operator. The μTBS testing was performed 8 h after bonding and after 6 months of storing the specimens in water. Pre-test failures (PTFs) of specimens were included in the analysis, attributing them a value of 1 MPa. Prospective clinical studies on cervical restorations (Class V) with an observation period of at least 18 months were searched in the literature. The clinical outcome variables were retention loss, marginal discoloration and marginal integrity. Furthermore, an index was formulated to be better able to compare the laboratory and clinical results. Estimates of adhesive effects in a linear mixed model were used to summarize the clinical performance of each adhesive between 12 and 36 months. Spearman correlations between these clinical performances and the μTBS values were calculated subsequently.

Results

Thirty-six clinical studies with 15 adhesive/restorative systems for which μTBS data were also available were included in the statistical analysis. In general 3-step and 2-step etch-and-rinse systems showed higher bond strength values than the 2-step/3-step self-etching systems, which, however, produced higher values than the 1-step self-etching and the resin modified glass ionomer systems. Prolonged water storage of specimens resulted in a significant decrease of the mean bond strength values in 5 adhesive systems (Wilcoxon, p < 0.05). There was a significant correlation between μTBS values both after 8 h and 6 months of storage and marginal discoloration (r = 0.54 and r = 0.67, respectively). However, the same correlation was not found between μTBS values and the retention rate, clinical index or marginal integrity.

Significance

As μTBS data of adhesive systems, especially after water storage for 6 months, showed a good correlation with marginal discoloration in short-term clinical Class V restorations, longitudinal clinical trials should explore whether early marginal staining is predictive for future retention loss in non-carious cervical restorations.     

Primary dentin etching time,bond strength and ultra-structure characterization of dentin surfaces

Objectives

To evaluate the effect of shortening the etching time on roughness, microhardness and bond strength of three adhesive systems to primary tooth dentin.

Methods

Flat dentin surfaces from primary molars were randomly assigned to six experimental groups. Three different adhesive systems were used: an etch-and-rinse adhesive (Single Bond), a two-step self-etching (Clearfil SE Bond), and a one-step self-etching (One-Up Bond F) adhesive. In half of the specimens, the recommended etching time was used, in the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and stored in a humid environment for 24 h at 37 °C. Specimens were sectioned into 1 mm² beams and tested for microtensile bond strength (MTBS). Debonded surfaces were analyzed by scanning electron microscopy (SEM). Additional surfaces were conditioned for microhardness measurements (KHN) and for atomic force microscopy (AFM) analysis. Intertubular and total surface roughness (Ra) were recorded. Results were analyzed with ANOVA and Student–Newman–Keuls tests (P < 0.05).

Results

Single Bond and Clearfil SE Bond showed higher MTBS than One-Up Bond F. Bond strength and intertubular roughness increased when Single Bond and One-Up Bond F were used with a reduced etching time. For Clearfil SE Bond no differences in MTBS were detected when reducing the etching time. The application of phosphoric acid, Clearfil SE Bond primer and One-Up Bond F decreases dentin microhardness.

Conclusions

Shortening One-Up Bond F application time and reducing the etching time of phosphoric acid to one-half of the manufacturer's recommended etching time when using Single Bond are recommended when bonding to primary dentin.     

Influence of glutaraldehyde priming on bond strength of an experimental adhesive system applied to wet and dry dentine

Objectives

This study tested the following null hypotheses: (1) there is no difference in resin–dentine bond strength when an experimental glutaraldehyde primer solution is added prior to bonding procedures and (2) there is no difference in resin–dentine bond strength when experimental glutaraldehyde/adhesive system is applied under dry or wet demineralized dentine conditions.

Methods

Extracted human maxillary third molars were selected. Flat, mid-coronal dentine was exposed for bonding and four groups were formed. Two groups were designated for the dry and two for the wet dentine technique: DRY: (1) Group GD: acid etching + glutaraldehyde primer (primer A) + HEMA/ethanol primer (primer B)-under dried dentine + unfilled resin; (2) Group D: the same as GD, except for primer A application; WET: (3) Group GW: the same as GD, but primer B was applied under wet dentine condition; (4) Group W: the same as GW, except for primer A application. The bonding resin was light-cured and a resin core was built up on the adhesive layer. Teeth were then prepared for microtensile bond testing to evaluate bond strength. The data obtained were submitted to ANOVA and Tukey's test (α = 0.05).

Results

Glutaraldehyde primer application significantly improved resin–dentine bond strength. No significant difference was observed when the same experimental adhesive system was applied under either dry or wet dentine conditions. These results allow the first null hypothesis to be rejected and the second to be accepted.

Conclusion

Glutaraldehyde may affect demineralized dentine properties leading to improved resin bonding to wet and dry substrates.     

Improved degree of conversion of model self-etching adhesives through their interaction with dentine

Objective

To investigate the correlation of the chemical interaction between model self-etching adhesives and dentine with the degree of conversion (DC) of the adhesives.

Methods

The model self-etching adhesives contained bis[2-methacryloyloxy)ethyl] phosphate (2MP) and 2-hydroxyethyl methacrylate (HEMA) with a mass ratio of 1/1, and 0-40% water contents, respectively. The adhesives were applied either onto the prepared dentine surface or unreactive substrates (such as glass slides), agitated for 15 s, then light-cured for 40 s. The DCs of the adhesives were determined using micro-Raman spectral and mapping analysis.

Results

The DCs of the adhesives cured on the dentine substrate were found to be significantly higher than those on the unreactive glass substrate. Moreover, the DCs of the adhesives displayed a decreasing trend as the distance from the dentine surface became greater. The chemical interaction of the acidic 2MP/HEMA adhesives with the mineral apatite in dentine was proposed to play a significant role for the observations. The chemical interaction could be validated by the spectral comparison in the phosphate regions of 1100 cm⁻¹ and 960 cm⁻¹ in the Raman spectra. The results also revealed a notable influence of water content on the DC of adhesives. The DCs of the adhesive at 10% water content exhibited the highest DC level for both substrates.

Conclusions

Interaction with dentine dramatically improved the degree of conversion of self-etching adhesives. Our ability to chemically characterise the a/d interface including in situ detection of the DC distribution is very important in understanding self-etching adhesive bonding under in vivo conditions.     

Effect of 2% chlorhexidine on dentin microtensile bond strengths and nanoleakage of luting cements

Objectives

The aim of this study was to investigate the effect of pre-treatment by chlorhexidine on the microtensile bond strength (mTBS) of resin cements and nanoleakage at the resin–dentine interfaces.

Methods

Cylindrical composite blocks were luted to human dentine using resin cements (RelyX ARC, 3M ESPE: ARC; Panavia F, Kuraray Medical Inc.: PF; RelyX Unicem, 3M ESPE: UN) with/without pre-treatment by 2% chlorhexidine digluconate (CAVITY CLEANSER, Bisco, Inc., Schaumburg, IL, USA). CAVITY CLEANSER was applied on the acid etched dentine for 60 s in the ARC group, and on smear layer-covered dentine in the PF and UN groups. After storage in water for 24 h, the bonded teeth were sectioned into 1 mm thick slabs and further into 0.9 mm × 0.9 mm beams. After immersion in water or ammoniacal silver nitrate for 24 h, the beams were stressed to failure in tension. The fractured surfaces were examined by field-emission scanning electron microscopy (FE-SEM) using backscattered electron mode. The silver-stained slabs were used to examine nanoleakage within the bonded interface by FE-SEM.

Results

The resin cement and chlorhexidine treatment had significant effects (p < 0.0001) on mTBS; while the storage media had no significant effect (p = 0.435). The mTBS of ARC was significantly higher than the other cements. Chlorhexidine reduced mTBS and produced pronounced nanoleakage when PF and UC were luted to dentine.

Conclusions

Pre-treatment with chlorhexidine affected the integrity of dentine bonding with PF and UC, while there was no adverse effect on coupling of ARC.     

Effect of surface pre-treatments on the zirconia ceramic-resin cement microtensile bond strength

Objective

To evaluate the influence of different surface treatments on the microtensile bond strength of resin cement to zirconia ceramic.

Materials and methods

Twelve cylinder-shaped (∅ 12 × 5.25 mm high) blocks of a commercial zirconium-oxide ceramic (Cercon^® Zirconia, DENTSPLY) were randomly divided into 4 groups (n = 3), based on the surface treatment to be performed: (1) airborne particle abrasion with 125 μm Al₂O₃ particles (S); (2) selective infiltration etching (SIE); (3) experimental hot etching solution applied for 30 min (ST) and (4) no treatment (C). Paradigm MZ100 blocks (3M ESPE) were cut into twelve cylinders of 4 mm in thickness. Composite cylinders were bonded to conditioned ceramics using a resin cement (Calibra^®, DENTSPLY), in combination with the proprietary adhesive system. After 24 h bonded specimens were cut into microtensile sticks and loaded in tension until failure. Bond strength data were analyzed with Kruskall-Wallis and Dunn's Multiple Range test for multiple comparisons (p < 0.05). Failure mode distribution was recorded and the interfacial morphology of debonded specimens was analyzed using a scanning electron microscope (SEM).

Results

Bond strength values achieved after SIE and ST treatment were significantly higher than after S treatment and without any treatment (p < 0.05). Premature failures were mostly recorded in the S group.

Significance

Conditioning the high-strength ceramic surface with SIE and ST treatments yielded higher bond strengths of the resin cement than when zirconia ceramic was treated with airborne particle abrasion or left untreated.     

Effect of reducing agents on bond strength to NaOCl-treated dentin

Objective

The purpose of this study was to evaluate the effect of three antioxidant/reducing agents with different application times on microtensile bond strengths to sodium hypochlorite-treated dentin.

Methods

The occlusal surfaces of 24 extracted human third molars were horizontally cut to expose sound dentin. The teeth were divided into eight groups. The dentin surfaces of the teeth were treated as follows: group 1, no treatment; group 2, treated with 6% sodium hypochlorite (NaOCl) for 30 s; groups 3-8, applications of 10% sodium ascorbate solution, 100 μM rosmarinic acid solution or Accel for 5 or 10 s after the same treatment as in group 2. All treated dentin surfaces were bonded with a 2-step self-etching adhesive system (Clearfil Protect Bond) and restored with a resin composite (Clearfil AP-X). After storage in water for 24 h, the bonded specimens were subjected to the microtensile bond test at a crosshead speed of 1.0 mm/min. Data were analyzed by a one-way ANOVA and Tukey test (p < 0.05).

Results

The NaOCl-treated group had significantly lower bond strength than the control group (p < 0.05). The application of sodium ascorbate solution for 5 or 10 s did not significantly increase the compromised bonding to NaOCl-treated dentin (p > 0.05). On the other hand, Accel and rosmarinic acid solution had significant reversal effects with the same application times (p < 0.05).

Significance

The reversal effect on compromised bonding to NaOCl-treated dentin depended upon the type of antioxidant within the short application time. Applying Accel or rosmarinic acid for 5 or 10 s improved bond strengths to NaOCl-treated dentin.     

Effect of chlorhexidine on initial adhesion of fiber-reinforced post to root canal

Objectives

Chlorhexidine is used as final irrigant before endodontic obturation and fiber-reinforced composite posts are recommended for restoration retention. Our aim was to evaluate the effect of chlorhexidine on adhesion of cements used in post cementation. We hypothesized that chlorhexidine would not negatively affect the immediate bond strength.

Methods

Root canals of eighty human extracted third molars were prepared for post cementation with each post systems’ own burs. Four commercially available FRC posts (Glassix, D.T.Light-Post, Unicore, everStickPOST) with three cements (Duo-link with All-bond 2, PermaFlo DC with PermaFlo DC Primers, RelyX Unicem) were used. After etching, except with self-etching RelyX Unicem, the post spaces were irrigated either with 2% chlorhexidine (Consepsis) or physiological saline for 60 s. With RelyX Unicem, respective treatments were done before cement application. The roots (n = 5 per group) were cut into 2 mm thick dentin discs. The bond strength was measured with push-out method, and the failure mode was evaluated with a stereomicroscope.

Results

Significant differences in bond strength were observed between various post/cement combinations. Unicore/PermaFlo DC and everStickPOST/RelyX Unicem showed significantly higher bond strengths than Glassix or D.T.Light-Post with Duo-link both with saline and chlorhexidine. Chlorhexidine improved the bond strength slightly with all posts/cements except with D.T.Light-Post, but the differences were not statistically significant. With chlorhexidine, significant reduction of adhesive failures towards dentin cohesive or mixed failures was observed with all posts/cements except with everStickPOST.

Conclusion

Chlorhexidine did not negatively affect the push-out bond strength in post bond cementation.