Purpose: To compare the adhesive capability of the new adhesive Prompt L-Pop (ESPE) with that of ... more Purpose: To compare the adhesive capability of the new adhesive Prompt L-Pop (ESPE) with that of two total-etch adhesive systems—EBS Multi (ESPE) and Prime&Bond NT (Dentsply).Methods: Extracted human molars were bonded and prepared for microtensile dentin bond strength (μTBS) testing using Prompt L-Pop, EBS Multi, and Prime&Bond NT combined with Pertac II (composite) or Hytac Aplitip (compomer). Prompt L-Pop was applied using five different protocols: (1) as an ‘all-in-one’ self-conditioning adhesive, as per manufacturer's instructions (LP); (2) as a self-etching primer combined with a separate bonding resin (LP/self-etch 2-step); (3) as a classical primer used upon etching dentin with phosphoric acid, followed by a bonding resin (LP/total-etch 3-step); (4) as a multi-application ‘all-in-one‘ self-conditioning adhesive (LP/multi-coat) to leave a visibly glossy dentin surface; and (5) as a filled adhesive, upon adding quartz fillers to its composition (LP/filled). After 24 h of storage in water at 37°C the μTBS were measured in an Instron machine. Corresponding interfaces of the same specimens were micromorphologically analyzed using SEM and TEM.Results: When used with a composite resin, LP/filled and LP/multi-coat resulted in significantly higher μTBS than LP. The addition of an extra adhesive bonding resin (LP/self-etch 2-step) had no effect on bond strength. The use of Prompt L-Pop as a primer of a fourth-generation adhesive (LP/total-etch 3-step) replacing the EBS Multi primer, resulted in lower bond strengths than those of the original EBS Multi. LP/multi-coat showed similar μTBS to Prime&Bond NT (P&BNT). When used with a compomer, LP exhibited higher bond strengths than when used with the resin composite and was as effective as the experimental groups LP/filled and LP/multi-coat and the control group P&BNT. The SEM evaluation showed an inconsistent hybrid layer for the LP specimens, whereas in both the LP/filled and LP/multi-coat specimens a hybrid layer was clearly evident. Under the TEM all groups displayed dentin hybridization with dissolved smear plugs in the specimens that had been conditioned with Prompt L-Pop without a separate etching step. In many tubules of specimens conditioned with LP (as per manufacturer's instructions), fillers of the resin composite were present within the dentinal tubules.Conclusions: When combined with a resin composite, Prompt L-Pop resulted in statistically lower bond strengths when applied in one layer than when applied in multiple layers. Prompt L-Pop also resulted in higher bond strengths when used with a polyacid-modified composite resin than with a composite resin. When applied in multiple coats, Prompt L-Pop results in bond strengths that are not statistically different from those of Prime&Bond NT, a total-etch adhesive.
Objectives: Recently, a new generation of simplified one-bottle dentin bonding systems, sensitive... more Objectives: Recently, a new generation of simplified one-bottle dentin bonding systems, sensitive to variations in the degree of substrate moisture, was introduced. This in vitro project compared the dentin bond strengths and interfacial ultra-morphology formed by three one-bottle bonding systems [OptiBond SOLO (ethanol-based), Prime&Bond 2.1 (acetone-based), and Single Bond (ethanol- and water-based)]. The null hypothesis tested was that re-wetting a dried dentin surface with a HEMA aqueous solution would not result in bond strengths, and resin impregnation into demineralized dentin, comparable to those obtained for moist dentin.Methods: Dentin specimens were assigned to the following three etched surface conditions: moist dentin-control group; dentin dried for 5 s; and dentin dried for 5 s and re-moistened with a commercial 35% HEMA aqueous solution. Mean shear bond strengths were calculated and analyzed with one- and two-way ANOVA. Dentin discs treated with the same combination of surface condition/adhesive were processed and observed under both transmission and scanning electron microscopes.Results: For moist dentin, the morphology of the resin–dentin interfaces showed penetration of the dentin adhesives to the depth of the transition between demineralized and unaffected dentin. Drying dentin for 5 s resulted in a significant decrease in mean bond strengths and an incompletely infiltrated collagen structure with areas of unveiled collagen fibers, regardless of the solvent. Re-wetting dentin with the aqueous HEMA solution re-established the level of bond strengths obtained to moist dentin and resulted in a raise of the fiber network with simultaneous increase in interfibrillar space dimensions.Significance: The results suggest that the use of an aqueous HEMA solution might compensate for the dryness induced on dentin surfaces by using air blasts from an air syringe, after rinsing off the etchant. As the behavior of the material that contained water was also affected by surface dryness, the percentage of water included in the composition of current ethanol- and water-based adhesives, such as Single Bond, may not be enough to compensate for the collapse of the collagen filigree upon drying.
It has been suggested that the hybrid layer (HL) does not play any important role in the mechanis... more It has been suggested that the hybrid layer (HL) does not play any important role in the mechanism of adhesion to dentin. To substantiate this hypothetical insignificance of the HL, sodium hypochlorite (NaOCl) has been used to remove collagen from etched dentin prior to bonding.Objectives: The present study was conducted to determine the effect of a commercial 10% NaOCl gel on the dentin shear bond strengths and HL ultra-morphology of two simplified dentin adhesives. The null hypothesis tested was that treatment of etched dentin collagen with NaOCl would not compromise dentin bonding.Methods: The labial surface of eighty bovine incisors was polished to expose middle dentin. The specimens were randomly assigned to two total-etch adhesive systems (N=40): Prime&Bond NT (Dentsply Caulk); and Single Bond (3M Dental Products Division). After rinsing off the etchant, one drop of 10% NaOCl (AD Gel, Kuraray Ltd.) was applied to the etched dentin surface and left for 0 (control), 15, 30, or 60 s. The gel was rinsed off with water and the dentin surface kept visibly moist prior to the application of the adhesive as per manufacturer's instructions. The respective composite resin was subsequently applied and light-cured. After 24 h in water at 37°C, the specimens were thermocycled for 500 cycles in baths kept at 5 and 55°C and the shear bond strengths measured. The data were analyzed with two-way ANOVA. For TEM, sixteen dentin disks were taken from middle dentin of extracted human third molars, assigned to the eight treatment sequences, and observed.Results: The increase in the NaOCl application time resulted in a progressive decrease in shear bond strengths for both dentin adhesives. For Single Bond, the application of AD Gel for 60 s resulted in a reduction of bond strengths to 38% of that obtained for the control. For Prime&Bond NT, the mean bond strength obtained when AD Gel was applied for 60 s was 31% of that obtained for the control. The application of AD Gel resulted in distinct morphology for each one of the two adhesives tested. For Single Bond, the general morphology of the collagen network was maintained, regardless of the deproteinization time. The interfibrillar space within the collagen network increased with increasing deproteinization times. For Prime&Bond NT, the general appearance of the HL was maintained for deproteinization times of 15 and 30 s. When the NaOCl gel was applied for 60 s, the morphological appearance of the HL lost its fibrillar arrangement. While remnants of the collagen fibers were observed in one of the dentin disks, the other specimen showed an amorphous structure without any discernible HL morphological features.Significance: The integrity of the collagen fibrils left exposed upon acid-etching plays a major role in the mechanism of adhesion of the specific adhesive systems tested in this study. The intermingling of the adhesive monomers with the filigree of collagen fibers or HL should still be considered the paramount dentin bonding mechanism.
Purpose: To compare the adhesive capability of the new adhesive Prompt L-Pop (ESPE) with that of ... more Purpose: To compare the adhesive capability of the new adhesive Prompt L-Pop (ESPE) with that of two total-etch adhesive systems—EBS Multi (ESPE) and Prime&Bond NT (Dentsply).Methods: Extracted human molars were bonded and prepared for microtensile dentin bond strength (μTBS) testing using Prompt L-Pop, EBS Multi, and Prime&Bond NT combined with Pertac II (composite) or Hytac Aplitip (compomer). Prompt L-Pop was applied using five different protocols: (1) as an ‘all-in-one’ self-conditioning adhesive, as per manufacturer's instructions (LP); (2) as a self-etching primer combined with a separate bonding resin (LP/self-etch 2-step); (3) as a classical primer used upon etching dentin with phosphoric acid, followed by a bonding resin (LP/total-etch 3-step); (4) as a multi-application ‘all-in-one‘ self-conditioning adhesive (LP/multi-coat) to leave a visibly glossy dentin surface; and (5) as a filled adhesive, upon adding quartz fillers to its composition (LP/filled). After 24 h of storage in water at 37°C the μTBS were measured in an Instron machine. Corresponding interfaces of the same specimens were micromorphologically analyzed using SEM and TEM.Results: When used with a composite resin, LP/filled and LP/multi-coat resulted in significantly higher μTBS than LP. The addition of an extra adhesive bonding resin (LP/self-etch 2-step) had no effect on bond strength. The use of Prompt L-Pop as a primer of a fourth-generation adhesive (LP/total-etch 3-step) replacing the EBS Multi primer, resulted in lower bond strengths than those of the original EBS Multi. LP/multi-coat showed similar μTBS to Prime&Bond NT (P&BNT). When used with a compomer, LP exhibited higher bond strengths than when used with the resin composite and was as effective as the experimental groups LP/filled and LP/multi-coat and the control group P&BNT. The SEM evaluation showed an inconsistent hybrid layer for the LP specimens, whereas in both the LP/filled and LP/multi-coat specimens a hybrid layer was clearly evident. Under the TEM all groups displayed dentin hybridization with dissolved smear plugs in the specimens that had been conditioned with Prompt L-Pop without a separate etching step. In many tubules of specimens conditioned with LP (as per manufacturer's instructions), fillers of the resin composite were present within the dentinal tubules.Conclusions: When combined with a resin composite, Prompt L-Pop resulted in statistically lower bond strengths when applied in one layer than when applied in multiple layers. Prompt L-Pop also resulted in higher bond strengths when used with a polyacid-modified composite resin than with a composite resin. When applied in multiple coats, Prompt L-Pop results in bond strengths that are not statistically different from those of Prime&Bond NT, a total-etch adhesive.
Objectives: Recently, a new generation of simplified one-bottle dentin bonding systems, sensitive... more Objectives: Recently, a new generation of simplified one-bottle dentin bonding systems, sensitive to variations in the degree of substrate moisture, was introduced. This in vitro project compared the dentin bond strengths and interfacial ultra-morphology formed by three one-bottle bonding systems [OptiBond SOLO (ethanol-based), Prime&Bond 2.1 (acetone-based), and Single Bond (ethanol- and water-based)]. The null hypothesis tested was that re-wetting a dried dentin surface with a HEMA aqueous solution would not result in bond strengths, and resin impregnation into demineralized dentin, comparable to those obtained for moist dentin.Methods: Dentin specimens were assigned to the following three etched surface conditions: moist dentin-control group; dentin dried for 5 s; and dentin dried for 5 s and re-moistened with a commercial 35% HEMA aqueous solution. Mean shear bond strengths were calculated and analyzed with one- and two-way ANOVA. Dentin discs treated with the same combination of surface condition/adhesive were processed and observed under both transmission and scanning electron microscopes.Results: For moist dentin, the morphology of the resin–dentin interfaces showed penetration of the dentin adhesives to the depth of the transition between demineralized and unaffected dentin. Drying dentin for 5 s resulted in a significant decrease in mean bond strengths and an incompletely infiltrated collagen structure with areas of unveiled collagen fibers, regardless of the solvent. Re-wetting dentin with the aqueous HEMA solution re-established the level of bond strengths obtained to moist dentin and resulted in a raise of the fiber network with simultaneous increase in interfibrillar space dimensions.Significance: The results suggest that the use of an aqueous HEMA solution might compensate for the dryness induced on dentin surfaces by using air blasts from an air syringe, after rinsing off the etchant. As the behavior of the material that contained water was also affected by surface dryness, the percentage of water included in the composition of current ethanol- and water-based adhesives, such as Single Bond, may not be enough to compensate for the collapse of the collagen filigree upon drying.
It has been suggested that the hybrid layer (HL) does not play any important role in the mechanis... more It has been suggested that the hybrid layer (HL) does not play any important role in the mechanism of adhesion to dentin. To substantiate this hypothetical insignificance of the HL, sodium hypochlorite (NaOCl) has been used to remove collagen from etched dentin prior to bonding.Objectives: The present study was conducted to determine the effect of a commercial 10% NaOCl gel on the dentin shear bond strengths and HL ultra-morphology of two simplified dentin adhesives. The null hypothesis tested was that treatment of etched dentin collagen with NaOCl would not compromise dentin bonding.Methods: The labial surface of eighty bovine incisors was polished to expose middle dentin. The specimens were randomly assigned to two total-etch adhesive systems (N=40): Prime&Bond NT (Dentsply Caulk); and Single Bond (3M Dental Products Division). After rinsing off the etchant, one drop of 10% NaOCl (AD Gel, Kuraray Ltd.) was applied to the etched dentin surface and left for 0 (control), 15, 30, or 60 s. The gel was rinsed off with water and the dentin surface kept visibly moist prior to the application of the adhesive as per manufacturer's instructions. The respective composite resin was subsequently applied and light-cured. After 24 h in water at 37°C, the specimens were thermocycled for 500 cycles in baths kept at 5 and 55°C and the shear bond strengths measured. The data were analyzed with two-way ANOVA. For TEM, sixteen dentin disks were taken from middle dentin of extracted human third molars, assigned to the eight treatment sequences, and observed.Results: The increase in the NaOCl application time resulted in a progressive decrease in shear bond strengths for both dentin adhesives. For Single Bond, the application of AD Gel for 60 s resulted in a reduction of bond strengths to 38% of that obtained for the control. For Prime&Bond NT, the mean bond strength obtained when AD Gel was applied for 60 s was 31% of that obtained for the control. The application of AD Gel resulted in distinct morphology for each one of the two adhesives tested. For Single Bond, the general morphology of the collagen network was maintained, regardless of the deproteinization time. The interfibrillar space within the collagen network increased with increasing deproteinization times. For Prime&Bond NT, the general appearance of the HL was maintained for deproteinization times of 15 and 30 s. When the NaOCl gel was applied for 60 s, the morphological appearance of the HL lost its fibrillar arrangement. While remnants of the collagen fibers were observed in one of the dentin disks, the other specimen showed an amorphous structure without any discernible HL morphological features.Significance: The integrity of the collagen fibrils left exposed upon acid-etching plays a major role in the mechanism of adhesion of the specific adhesive systems tested in this study. The intermingling of the adhesive monomers with the filigree of collagen fibers or HL should still be considered the paramount dentin bonding mechanism.
Uploads
Papers