Shear Bond Strengths of One-Bottle Adhesives to Oil-Contaminated Enamel

Purpose: To evaluate resin bond strength to enamel contaminated with handpiece oil. Materials and Methods: Bovine teeth were randomly assigned to six groups of 20 teeth each for treatment with one of six different bonding systems (five one‐bottle and one multibottle). For each system, 10 enamel specimens were contaminated with handpiece oil before acid‐etching and 10 were contaminated after acid‐etching. The enamel was etched for 15 seconds using 35% phosphoric acid. Following adhesive application, composite resin was bonded using a gelatin capsule technique. Shear bond strengths from the two contaminated groups were compared to bond strengths to uncontaminated enamel obtained from a previous study that was performed by the same group of investigators, using the same facility, materials, and methods. Results: Two‐way analysis of variance (ANOVA) showed that the factor “surface contamination” did not have a significant effect on bond strength (p > .542). The type of adhesive and the interaction of adhesive and surface contamination were significant (p <.0001 and p <.003, respectively). When oil was applied before etching, mean bond strengths ranged from 18.0 ± 4.8 MPa for OptiBond SOLO (Kerr Corp., Orange, California) to 25.3 ± 5.6 MPa for Tenure Quik with Fluoride (Den‐Mat Corp., Santa Maria, California). With oil applied after etching, bond strengths ranged from 18.4 ± 8.0 MPa for Tenure Quik with Fluoride to 27.4 ± 5.4 MPa for Single Bond (3M Dental Products, St. Paul, Minnesota). For the same adhesive, comparing uncontaminated and “oil‐before‐etch” contaminated groups, the only statistically significant difference in bond strengths was for OptiBond SOLO: 21.8 ± 4.0 MPa (uncontaminated) versus 18.0 ± 4.8 MPa (oil before etch). Comparing uncontaminated and “oil‐after‐etch” groups, the only statistically significant difference was for Tenure: 24.5 ± 5.7 MPa (uncontaminated) and 18.4 ± 8.0 MPa (oil after etch). CLINICAL SIGNIFICANCE Surface contamination with handpiece lubricant oil does not impair appreciably the efficacy of the adhesives used in this study when bonding composite resin to enamel.     

Bond strength and etching pattern of adhesive systems to enamel: effects of conditioning time and enamel preparation

ABSTRACT

Statement of the problem: The performance of self‐etch systems on enamel is controversial and seems to be dependent on the application technique and the enamel preparation. Purpose of the Study: To examine the effects of conditioning time and enamel surface preparation on bond strength and etching pattern of adhesive systems to enamel. Materials and Methods: Ninety‐six teeth were divided into 16 conditions (N = 6) in function of enamel preparation and conditioning time for bond strength test. The adhesive systems OptiBond FL (Kerr, Orange, CA, USA), OptiBond SOLO Plus (Kerr), Clearfil SE Bond (Kuraray, Osaka, Japan), and Adper Prompt L‐Pop (3M ESPE, St. Paul, MN, USA) were applied on unground or ground enamel following the manufacturers’ directions or doubling the conditioning time. Cylinders of Filtek Flow (0.5‐mm height) were applied to each bonded enamel surface using a Tygon tube (0.7 mm in diameter; Saint‐Gobain Corp., Aurora, OH, USA). After storage (24 h/37°C), the specimens were subjected to shear force (0.5 mm/min). The data were treated by a three‐way analysis of variance and Tukey's test (α = 0.05). The failure modes of the debonded interfaces and the etching pattern of adhesives were observed using scanning electron microscopy. Results: Only the main factor “adhesive” was statistically significant (p < 0.001). The lowest bond strength value was observed for OptiBond FL. The most defined etching pattern was observed for 35% phosphoric acid and for Adper Prompt L‐Pop. Mixed failures were observed for all adhesives, but OptiBond FL showed cohesive failures in resin predominantly. Conclusions: The increase in the conditioning time as well as the enamel pretreatment did not provide an increase in the resin–enamel bond strength values for the studied adhesives.

CLINICAL SIGNIFICANCE

The surface enamel preparation and the conditioning time do not affect the performance of self‐etch systems to enamel.     

Bonding characteristics of self-etching adhesives to intact versus prepared enamel

Purpose: This study tested the null hypothesis that the preparation of the enamel surface would not affect the enamel microtensile bond strengths of self‐etching adhesive materials. Materials and Methods: Ten bovine incisors were trimmed with a diamond saw to obtain a squared enamel surface with an area of 8 × 8 mm. The specimens were randomly assigned to five adhesives: (1) ABF (Kuraray), an experimental two‐bottle self‐etching adhesive; (2) Clearfil SE Bond (Kuraray), a two‐bottle self‐etching adhesive; (3) One‐Up Bond F (Tokuyama), an all‐in‐one adhesive; (4) Prompt L‐Pop (3M ESPE), an all‐in‐one adhesive; and (5) Single Bond (3M ESPE), a two‐bottle total‐etch adhesive used as positive control. For each specimen, one half was roughened with a diamond bur for 5 seconds under water spray, whereas the other half was left unprepared. The adhesives were applied as per manufacturers' directions. A universal hybrid composite resin (Filtek Z250, 3M ESPE) was inserted in three layers of 1.5 mm each and light‐cured. Specimens were sectioned in X and Y directions to obtain bonded sticks with a cross‐sectional area of 0.8 ± 0.2 mm². Sticks were tested in tension in an Instron at a cross‐speed of 1 mm per minute. Statistical analysis was carried out with two‐way analysis of variance and Duncan's test at p <. 05. Ten extra specimens were processed for observation under a field‐emission scanning electron microscope. Results: Single Bond, the total‐etch adhesive, resulted in statistically higher microtensile bond strength than any of the other adhesives regardless of the enamel preparation (unprepared = 31.5 MPa; prepared = 34.9 MPa, not statistically different at p < 05). All the self‐etching adhesives resulted in higher microtensile bond strength when enamel was roughened than when enamel was left unprepared. However, for ABF and for Clearfil SE Bond this difference was not statistically significant at p > 05. When applied to ground enamel, mean bond strengths of Prompt L‐Pop were not statistically different from those of Clearfil SE Bond and ABF. One‐Up Bond F did not bond to unprepared enamel. Commercial self‐etching adhesives performed better on prepared enamel than on unprepared enamel. The field‐emission scanning electron microscope revealed a deep interprismatic etching pattern for the total‐etch adhesive, whereas the self‐etching systems resulted in an etching pattern ranging from absent to moderate. CLINICAL SIGNIFICANCE For the recently introduced all‐in‐one self‐etching dental adhesives, instrumentation of enamel may be critical for their ability to optimally bond to enamel.     

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.     

Fatigue behaviour of different dentin adhesives

The aim of this in vitro study was to compare quasistatic and cyclic fatigue dentin bond strength of modern adhesive systems representing different generations. One hundred and fifty cavities were made in discs of freshly extracted human third molars and filled with direct resin composite restorations. Dentin adhesives of different generations (SY = Syntac Classic, multi-step system with self-etching primer; SE = Syntac Classic with additional phosphoric acid etching prior to application of the self-etching primer; SB = Scotchbond Multi-Purpose Plus, multi-step system with total etching; PE = Prime&Bond 2.1, single-step system with and without [PB] total etching) were used in combination with one hybrid composite. After 21 days of storage, 10 specimens for each adhesive system were subjected to thermocycling (1150 cycles) for 24 h and were afterwards debonded in a push-out test. Another 20 specimens were tested with cyclic fatigue according to the staircase method with 5000 cycles for each specimen. Static and cyclic push-out bond strengths, respectively, for each group were (MPa): SY 16.9±0.9 and 14.2±1.7, SE 17.5±1.8 and 14.8±3.4, SB 18.5±1.7 and 13.9±2.1, PB 14.6±2.2 and 7.2±2.4, PE 13.4±2.2 and 6.8±1.8. Both quasistatic and dynamic bond strengths revealed better values for the multi-step systems (P<0.05). All adhesive systems tested revealed a significant fatigue behaviour which was more pronounced for the one-bottle system with a decrease of about 50% independent of additional dentin etching. Received: 19 October 1998 / Accepted: 1 February 1999     

Dentin diffusion of HEMA released from etch-and-rinse and self-etch bonding systems

The aim of this in vitro study was to determine the diffusion of 2-hydroxyethyl methacrylate (HEMA) released from different bonding systems (BS) through dentin. Occlusal cavities with a remaining dentin thickness (RDT) of 0.5 mm (n=90) and 0.25 mm (n=80), respectively, were prepared in dentin discs of non-carious human molars. Artificial pulp chambers were attached to the pulpal side of each dentin disc. Bonding systems were applied with (Clearfil SE Bond, OptiBond FL, OptiBond Solo Plus) or without (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, OptiBond FL, OptiBond Solo Plus Self Etch, Xeno III) prior phosphoric acid etching. HEMA was detected by gas chromatography/mass spectrometry (n=10 per BS and RDT). The highest mean HEMA concentration was found in the 0.25 mm RDT group treated with OptiBond FL (13.3 microg) and the lowest mean HEMA concentration was detected in the 0.5 mm RDT group treated with AdheSE (0.5 microg). At 0.25 mm RDT the quantities of HEMA recovered in the artificial pulp chambers were significantly higher than at 0.5 mm RDT, except for Clearfil SE Bond. Etching with phosphoric acid increased the detected HEMA quantities compared with self-etch BS. In deep cavity preparations, etching with phosphoric acid should be avoided in favor of the use of self-etch BS.     

Adhesion of multimode adhesives to enamel and dentin after one year of water storage

Objectives

This study aimed to evaluate the ultramorphological characteristics of tooth–resin interfaces and the bond strength (BS) of multimode adhesive systems to enamel and dentin.

Methods

Multimode adhesives (Scotchbond Universal (SBU) and All-Bond Universal) were tested in both self-etch and etch-and-rinse modes and compared to control groups (Optibond FL and Clearfil SE Bond (CSB)). Adhesives were applied to human molars and composite blocks were incrementally built up. Teeth were sectioned to obtain specimens for microtensile BS and TEM analysis. Specimens were tested after storage for either 24 h or 1 year. SEM analyses were performed to classify the failure pattern of beam specimens after BS testing.

Results

Etching increased the enamel BS of multimode adhesives; however, BS decreased after storage for 1 year. No significant differences in dentin BS were noted between multimode and control in either evaluation period. Storage for 1 year only reduced the dentin BS for SBU in self-etch mode. TEM analysis identified hybridization and interaction zones in dentin and enamel for all adhesives. Silver impregnation was detected on dentin–resin interfaces after storage of specimens for 1 year only with the SBU and CSB.

Conclusions

Storage for 1 year reduced enamel BS when adhesives are applied on etched surface; however, BS of multimode adhesives did not differ from those of the control group. In dentin, no significant difference was noted between the multimode and control group adhesives, regardless of etching mode.

Clinical relevance

In general, multimode adhesives showed similar behavior when compared to traditional adhesive techniques. Multimode adhesives are one-step self-etching adhesives that can also be used after enamel/dentin phosphoric acid etching, but each product may work better in specific conditions.

     

Microtensile bond strength of sealant and adhesive systems applied to occlusal primary enamel

PURPOSE: To compare the microtensile bond strength (muTBS) of a self-etch adhesive system (OptiBond Solo Self-Etch Adhesive System), two total etch adhesive system (OptiBond FL; OptiBond Solo), and a conventional sealant (Clinpro) applied to the occlusal surface of primary molars under saliva contamination. METHODS: Sealant and adhesive systems were applied under manufacturers' specifications with or without previous saliva contamination. After storage in distilled water at 37 degrees C for 24 hours, the specimens were longitudinally sectioned perpendicularly to the adhesive interface to obtain sticks (0.6 mm2) which were tested under a tensile load of 0.5 mm/minute. The bond failure modes were evaluated via scanning electron microscope. Repeated measures ANOVA followed by multiple comparisons using Bonferroni's technique was used to evaluate the effects of adhesive system and saliva contamination. The pre-test debonded specimens were included in the computation of the pTBS of each tooth. RESULTS: No association between failure mode and the values of muTBS was observed (P = 0.3605). The majority of fractures were of mixed type; no cohesive failure of enamel or composite resin was observed. No significant effect of saliva contamination was detected (P = 0.2044). OptiBond FL and Clinpro had equivalent average muTBS (34.5 +/- 2.2 MPa and 45.1 +/- 3.2 MPa, respectively) which are significantly higher than the corresponding average muTBS for OptiBond Solo Plus and OptiBond Solo SE which may also be considered equivalent (19.1 +/- 2.3 MPa and 9.8 +/- 2.3 MPa, respectively).     

Effect of fracture strength of primer-adhesive mixture on bonding effectiveness.

OBJECTIVE: The purpose of this study was to measure the micro-tensile bond strength (microTBS) of two adhesives to dentin and to correlate this microTBS with the micro-tensile fracture strength (microTFS) of primer-adhesive mixtures of the two adhesives. METHODS: The three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE Bond (Kuraray) were used to bond Filtek Z100 (3M ESPE) to twenty mid-coronal dentin surfaces. The microTBS was determined at 1 and 24 h after light-curing. In addition, the microTFS of primer-adhesive mixtures (primer:adhesive=1:3 by weight) and of the pure adhesives (controls) were measured after the same time intervals. RESULTS: The microTBS to dentin of OptiBond FL at 24 h was significantly higher than at 1 h and than the microTBS of Clearfil SE Bond at 24 h. The mean microTFS of the primer-adhesive mixtures was always lower than the microTFS of the respective adhesives. The highest reduction in microTFS due to mixing primer with the adhesive resin was measured for Clearfil SE Bond. Both the microTFS of the primer-adhesive mixtures and the pure adhesives of OptiBond FL and Clearfil SE Bond increased with time. SIGNIFICANCE: The early 1 h microTBS to dentin was lower than the 24 h microTBS for OptiBond FL, but not for Clearfil SE Bond. Differences in polymerization efficiency as well as in the resulting interfacial strength may explain such varying early bond strengths to dentin.     

Influence of caries infiltrant contamination on shear bond strength of different adhesives to dentin

Objectives

To analyze whether the contamination with a caries infiltrant system impairs the adhesive performance of etch-and-rinse and self-etching adhesives on dentin.

Materials and methods

Dentin contamination with the caries infiltrant system (Icon, DMG) was simulated by applying either hydrochloric acid (15 % HCl, Icon Etch, 15 s), the resin infiltrant (Icon infiltrant, 4 min), or both prior to the application of the respective adhesives (each group n?=?10). In the control groups, the etch-and-rinse adhesive (Optibond FL, Kerr) and the self-etching adhesive (iBOND Self Etch, Hereaus) were applied without former contamination with the infiltrant system. Additionally, the adhesive performance of the resin infiltrant alone was tested. Shear bond strength of a nano-hybrid composite was analyzed after thermocycling (5,000×, 5–55°C) of the specimens and analyzed by ANOVA/Scheffé post hoc tests (p?<?0.05) and Weibull statistics. Failure mode was inspected under a stereomicroscope at?×?25 magnification.

Results

Contamination with the resin infiltrant alone did not impair shear bond strength, while contamination with hydrochloric acid or with hydrochloric acid and the resin infiltrant reduced shear bond strength (MPa) of the adhesives (Optibond FL: 20.5?±?3.6, iBOND Self Etch: 17.9?±?2.6) significantly. Hydrochloric acid contamination increased the number of adhesive failures. The adhesive performance of the caries infiltrant system alone was insufficient.

Conclusion

The contamination with the caries infiltrant system impaired the shear bond strength of conventional dental adhesives.

Clinical relevance

Contamination of the caries infiltrant system on dentin should be avoided due to the detrimental effect of hydrochloric acid etching.     

Quantitative comparison of the water permeable zone among four types of dental adhesives used with a dual-cured composite

This study compared silver penetration in the adhesive interface among four versions of adhesives from the same manufacturer: OptiBond FL, OptiBond Solo Plus, OptiBond Solo Plus Dual Cure, and OptiBond Solo Plus Self-Etch, when coupled with dual-cured composite, CoreRestore 2 (Kerr). Twenty flat dentin surfaces were prepared using one of the adhesives and bonded with the composite, following the manufacturer's instructions. The surfaces were sectioned into 2-mm slabs and immersed in ammoniacal silver nitrate for 24 hours. Each specimen was exposed to a photodeveloping solution for eight hours and examined with a scanning electron microscope (SEM). The water permeable area occupied by the silver nitrate tracer was determined, and the relative weight of silver was analyzed by wavelength dispersive spectrometry (WDS). The OptiBond FL group had a significantly lower silver content than the other groups (p < 0.0001). Each group demonstrated different patterns of silver deposition within the adhesive layer and within various features of artifactual fracture from dehydration stress of the SEM. This may be indicative of weak links in the bonded interfaces. Simplified-step adhesives showed increased permeability, which can lead to disruption of coupling with composites.     

Effects of thermocycling and use of ElectroBond on microtensile strength and nanoleakage using commercial one‐step self‐etch adhesives

The aim of this study was to determine the effect of thermocycling and the use of an electronically assisted application technique on the microtensile bond strength and nanoleakage of bonded interfaces created using one‐step self‐etch adhesives. Composite build‐ups were bonded coronally to sectioned human molars using XENO III or Clearfil S³Bond. Adhesives were applied following the manufacturers’ instructions (control) or with the aid of an electrical application device (ElectroBond). Teeth were sectioned into non‐trimmed bonded beams for microtensile testing. Half of the specimens were subjected to 20,000 thermocycles, and the controls were not thermocycled. All specimens were tested to failure and peak stress was calculated. Additional specimens were prepared for nanoleakage analysis using transmission electron microscopy (TEM). The immediate bond strength of both adhesives increased as a result of using the ElectroBond device (XENO III 38.9 ± 8.1 MPa; Clearfil S³Bond 46.2 ± 9.9 MPa) compared with no use of the device (XENO III 26.7 ± 7.8 MPa; Clearfil S³Bond 38.9 ± 8.1 MPa). Thermocycling significantly decreased the bond strength of XENO III (27.1 ± 7.9 MPa with the use of ElectroBond; 20.7 ± 9.2 MPa without the use of ElectroBond); however, thermocycling did not affect the Clearfil S³Bond strength (47.2 ± 8.6 MPa with the use of ElectroBond; 33.6 ± 8.3 MPa without the use of ElectroBond). Reduced nanoleakage was found for both resins as a result of the use of the ElectroBond device, with or without thermocycling. Application of one‐step, self‐etch adhesives with the ElectroBond device significantly increased microtensile bond strength and reduced nanoleakage, but the effect of thermocycling was found to be brand‐dependent.     

Enamel microhardness and bond strengths of self‐etching primer adhesives

Adebayo OA, Burrow MF, Tyas MJ, Adams GG, Collins ML. Enamel microhardness and bond strengths of self‐etching primer adhesives. Eur J Oral Sci 2010; 118: 191–196. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci 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.     

One-day bonding effectiveness of new self-etch adhesives to bur-cut enamel and dentin

Self-etch adhesives try to solve difficulties commonly associated with the clinical application of etch-and-rinse adhesives. Their application procedure is considered less time-consuming and, more importantly, less technique-sensitive. The main objective of this study was to determine the bonding effectiveness to and the interaction with enamel/dentin of three contemporary one- and two-step self-etch adhesives by microtensile bond strength testing (microTBS), Fe-SEM and TEM when compared to a control two-step self-etch and a three-step etch-and-rinse adhesive. The one-step self-etch adhesive, Adper Prompt (3M ESPE), scored the lowest microTBS of all experimental and control adhesives tested. Conversely, the two-step self-etch adhesives Clearfil SE (Kuraray) and OptiBond Solo Plus Self-Etch (Kerr) approached the values obtained by the three-step etch-and-rinse control (OptiBond FL, Kerr) when bonded to enamel and dentin. Ultramorphological characterization showed that interfacial morphology and the pH of the self-etch primer/adhesive are strongly associated. The interaction with dentin varied from the formation of a submicron, hydroxyapatite-containing hybrid layer for the "mild" self-etch adhesive Clearfil SE to a 3-5 microm thick, hydroxyapatite-depleted hybrid layer for the "strong" self-etch adhesive Adper Prompt. The two-step self-etch adhesives AdheSE and OptiBond Solo Plus Self-Etch presented with a hybrid layer with a hydroxyapatite-depleted top part and a hydroxyapatite-containing base part and were therefore classified into a new group of self-etch adhesives, namely "intermediary strong" self-etch adhesives.     

Influence of Er,Cr:YSGG laser treatment on microtensile bond strength of adhesives to enamel

The current trend towards minimum-intervention dentistry has introduced laser technology as an alternative technique for cavity preparation. This study assessed the null hypothesis that enamel prepared either by Er,Cr:YSGG laser or conventional diamond bur is equally receptive to adhesive procedures. The buccal and lingual surfaces of 35 sound human molars were prepared with Er,Cr:YSGG laser or a medium-grit diamond bur. One etch&rinse (OptiBond FL) and three self-etch adhesives (Adper Prompt L-Pop, Clearfil SE Bond and Clearfil S3 Bond) were applied on laser-irradiated and bur-cut enamel, followed by the application of a 5-6 mm build-up of Z100. The micro-tensile bond strength (microTBS) was determined after 24 hours of storage in water at 37 degrees C. Prepared enamel surfaces and failure patterns were evaluated using a stereomicroscope and a field-emission-gun scanning electron microscope (Feg-SEM). The pTBS to laser-irradiated enamel was significantly lower than to bur-cut enamel (p<0.05), with the exception of Clearfil S3 Bond, which bonded equally effectively to both substrates. The latter presented the highest microTBS on laser-irradiated enamel, though it was not statistically different from the microTBS of OptiBond FL. SEM analysis revealed significant morphological alterations of the laser-irradiated enamel surface, such as areas of melted and recrystalized hydroxyapatite and deep extensive micro-cracks. In conclusion, the bonding effectiveness of adhesives to laser-irradiated enamel depends not only on the structural substrate alterations induced by the laser, but also on the characteristics of the adhesive employed.     

In-vitro Shear Bond Strength of Self-etching versus Traditional Adhesives for Orthodontic Luting

OBJECTIVE: To determine the enamel shear bond strength (SBS) of various established (Resulcin Aqua Prime & Monobond N [RA], Prompt L-Pot III [PLP]) and experimental (AC-Bond [AC], AC-Bond + Desensitizer [ACD]) self-etching adhesives in comparison to fourth (Total Etch, Primer and Bonding have separate liquids; OptiBond FL [FL]) and fifth-generation (Total Etch, Primer and Bonding "One Bottle"; Excite [EX], Gluma Comfort Bond [CB]) adhesives. MATERIALS AND METHODS: All adhesives were applied on flattened human enamel surfaces following the manufacturers' instructions and light-cured using a quartz-tungsten-halogen curing device. 3.5 x 2.0 mm Tetric Ceram A2 composite cylinders were sheared off (Zwick Universal-testing-machine 1445, 1 mm/min) after thermocycling (5-55 degrees C, 5000x). Normal distribution was tested for all groups and analysis of variance was conducted. The t-test (5% level, Bonferroni-correction) was used for statistical analysis to evaluate intergroup differences. RESULTS: Shear bond strength in enamel: Resulcin Aqua Prime & Monobond N: 27.0 +/- 5.8 MPa, Prompt L-Pop III: 15.9 +/- 3.4 MPa, AC-Bond: 28.1 +/- 4.4 MPa, AC-Bond + Desensitizer: 22.2 +/- 4.1 MPa, OptiBond FL: 33.2 +/- 3.2 MPa, Excite: 30.5 +/- 5.1 MPa, Gluma Comfort Bond: 30.1 +/- 3.7 MPa. OptiBond FL demonstrated significantly higher SBS (p < 0.002) in enamel than Resulcin Aqua Prime & Monobond N, AC-Bond, AC-Bond + Desensitizer and Prompt L-Pop III. Resulcin Aqua Prime & Monobond N performed significantly better than Prompt L-Pop III, but did not differ from AC-Bond or AC-Bond + Desensitizer. The SBS values of Excite and Gluma Comfort Bond were both on the same level of significance as AC-Bond and Resulcin Aqua Prime & Monobond N, but the former showed superior results to AC-Bond + Desensitizer and Prompt L-Pop III. Prompt L-Pop III yielded significantly lower SBS-values than all the other products evaluated. CONCLUSION: Resulcin Aqua Prime & Monobond N and AC-Bond did not differ significantly from established 5th-generation products. Further in-vivo studies are required to investigate intra-oral stability and resistance against changing forces and force directions.     

Effect of different gutta-percha solvents on the microtensile bond strength of various adhesive systems to pulp chamber dentin

Objectives

The aim of this study was to evaluate the effect of different endodontic solvents on the microtensile bond strength (μTBS) of various adhesives to pulp chamber dentin.

Material and methods

A total of 120 human third molars were selected. Canals were prepared with the ProTaper Universal system and obturated. The access cavities were then restored with resin composite. After 1 week, a retreatment procedure was applied as follows: control, no solvent was applied to the pulp chamber and experimental groups, three different solvents (chloroform, eucalyptol, and orange oil) were applied to the pulp chamber for 2 min. The canal filling was removed and calcium hydroxide (Ca[OH]₂) was placed into the canals. After 7 days, the Ca(OH)₂ was removed from the canals and the canals were re-obturated. Teeth were then divided into three subgroups according to the adhesive used. The samples were restored with a nanohybrid resin composite using three different adhesives: Clearfil SE Bond (CSE), Adper Easy One (AEO), and Single Bond 2 (SB2). The samples were aged with thermocycling. Teeth were sectioned, and a total of 20 dentin sticks were obtained for each subgroup. μTBS testing was then performed. The debonded surfaces were evaluated using scanning electron microscopy (SEM) analysis. Data were analyzed using two-way ANOVA and Tukey’s post hoc tests.

Results

Chloroform showed statistically lower mean μTBS values (14 ± 7.2 MPa) than control group did (19.2 ± 6.1 MPa) (p < 0.05). Orange oil (18.1 ± 6.3 MPa) and eucalyptol (16.9 ± 6.8 MPa) did not reduce the mean μTBS statistically (p > 0.05). Chloroform showed significantly lower bond strength for all adhesives (p < 0.05). Whereas orange oil did not reduce the mean μTBS values of all adhesive systems significantly (p > 0.05), eucalyptol reduced the μTBS values of all the groups, but the results were only statistically significant for SB2 (p < 0.05). CSE showed statistically higher bond strength (20.4 ± 6.8 MPa) than AEO (14.6 ± 5.3 MPa) and SB2 (16.3 ± 7.2 MPa) did (p < 0.05). There were no statistical differences between AEO and SB2 (p > 0.05). According to the SEM analysis of the debonded surfaces, adhesive failures were the most common type in all the groups, followed by mixed failures.

Conclusions

While chloroform reduced the mean bond strength of the adhesive resins, orange oil did not affect the bond strength of the adhesives. The effect of eucalyptol on bond strength depended on the type of adhesive system.

Clinical relevance

This study shows that endodontic solvents could affect the microtensile bond strength of adhesives to pulp chamber dentin.

     

Evaluation of low-viscosity bulk-fill composites regarding marginal and internal adaptation

This study aimed at evaluating the marginal and internal adaptation of low-viscosity bulk-fill composites to enamel and dentin using a self-etch or an etch-and-rinse adhesive without and with artificial ageing. Hundred and twenty-eight MOD cavities in extracted molars were assigned to eight groups (n = 16), restored with the adhesives OptiBond FL (OFL) or Xeno V+ (X) and two low-viscosity bulk-fill composites SDR or x-tra base, covered with Premise. Tetric EvoCeram Bulk Fill and Premise served as a control. n = 8 per group were subjected to prolonged water storage (180 days) and thermocycling (2500×). Scanning electron microscopy was used to determine marginal gaps (MG) and interfacial adhesive defects (IAD). There were no significant differences between composite types in 44 out of 48 (MG) or 43/48 (IAD) comparisons. More MG were observed with X than with OFL (14 out of 16 comparisons, two significant), while in 16 of 16 comparisons with X more IAD were observed (14 significant). After artificial ageing, MG generally increased (9/16 significant), compared to IAD (one significant). The performance of the investigated composite types concerning the integrity of the tooth-composites interface was comparable. Compared to the 1-step self-etch system, the bond with the 3-step etch-and-rinse adhesive was raised.

     

Self-etching aspects of a three-step etch-and-rinse adhesive

Purpose

The purpose of this study is to assess the marginal adaptation of cavities restored with a three-step etch-and-rinse adhesive, OptiBond FL (OFL) under different application protocols.

Materials and methods

Twenty-four class V cavities were prepared with half of the margins located in enamel and half in dentin. Cavities were restored with OFL and a microhybrid resin composite (Clearfil AP-X). Three groups (n?=?8) that differed in the etching technique were tested with thermomechanical loading, and specimens were subjected to quantitative marginal analysis before and after loading. Micromorphology of etching patters on enamel and dentin were observed with SEM. Data was evaluated with Kruskal–Wallis and Bonferroni post hoc test.

Results

Significantly lower percent CM (46.9?±?19.5) were found after loading on enamel in group 3 compared to group 1 (96.5?±?5.1) and group 2 (93.1?±?8.1). However, no significant differences (p?=?0.30) were observed on dentin margins.

Conclusions

Etching enamel with phosphoric acid but avoiding etching dentin before the application of OFL, optimal marginal adaptation could be obtained, evidencing a self-etching primer effect.

Clinical relevance

A reliable adhesive interface was attained with the application of the three-step etch-and-rinse OFL adhesive with a selective enamel etching, representing an advantage on restoring deep cavities.     

Adhesive systems used for sealing contaminated surfaces: a microleakage evaluation

The aim of this study was to compare two adhesive systems (OptiBond FL and OptiBond SOLO) used as a sole material for sealing pit and fissures on contaminated surfaces with respect to microleakage. After acid etching, 56 sound teeth were contaminated with 1microl of plasma and randomly divided into 8 groups (n = 7). The adhesives were light activated under two conditions (Optilux VCL-403 and VCL-500) for 30 s. Each specimen was exposed to one of the following aging treatments: thermal (4,000 X at 5-55 degrees C for 60 s) plus load cycling (225,000 X with 83.3 N) or thermal plus load and pH cycling (mineralizing/demineralizing solutions). Then, they were immersed in a 50% AgNO3 aqueous solution, sectioned twice and had dye penetration measured through digitized images. ANOVA methods were used to assess the main effects of the factors as well as their interactions. The results indicated a significant difference between the adhesive systems (p < 0.05), suggesting that OptiBond FL has a better performance with respect to microleakage and could be used as a sealing material in accidentally moist or contaminated surfaces.