Biomedical subjects

M F Burrow

Publications and source records attributed to M F Burrow.

At least 37 records · Page 2Linked to original sources

PubMed2001

A light curing method for improving marginal sealing and cavity wall adaptation of resin composite restorations.

OBJECTIVE: The aim of this study was to evaluate whether the method of light curing could influence: (a) marginal sealing and resin composite adaptation to the cavity wall; (b) polymerization contraction rate; and (c) the hardness at the top and bottom surfaces of a body of resin composite. METHODS: Standard cylindrical cavities, 1mm deep and 3mm in diameter were prepared on flat superficial dentin surfaces in bovine teeth. The teeth were bonded with one of two adhesive systems (Clearfil Photo Bond, and Super-Bond D Liner) and filled with a hybrid resin composite. The resins were cured using three light intensities of 600, 270 and 20mW/cm(2), and various curing times. After thermal cycling, the specimens were subjected to a dye penetration test to evaluate marginal sealing and adaptation of the resin composite to the cavity walls. In addition, using the same curing conditions, the rate of polymerization contraction was measured. The difference of hardness over time of composite specimens was measured using Knoop hardness measurements taken at the top and bottom surfaces of resin specimens made in a Teflon mold the same dimensions as the cavity prepared in dentin. RESULTS: When the composite was light cured with an initial light intensity of 270mW/cm(2) for 10s, a 5s interval then a light intensity of 600mW/cm(2) for 50s, the best marginal sealing and cavity wall adaptation was observed compared with the other curing modes. Earlier hardening occurred at the resin composite base compared with the top surface of the composite, and most of the polymerization contraction was completed during the initial flowable stage of the resin composite. All other methods demonstrated results with some degree of marginal opening and cavity wall gap formation, the worst being 600mW/s for 60s. SIGNIFICANCE: The use of a low initial light intensity (270mW/cm(2)) for 10s followed by high intensity light (600mW/cm(2)) for 50s provides the best adaptation of resin composite to cavity walls and possibly the least polymerization contraction stress.

Analysis of Variance↗

PubMed2001

The evaluation of four conditioners for glass ionomer cements using field-emission scanning electron microscopy.

OBJECTIVES: The purpose of this study was to evaluate the GIC-dentine interface morphology using FE-SEM after four different conditioners (Ketac Conditioner, Dentin Conditioner, Cavity Conditioner, and an experimental conditioner K-930), used with two RM-GICs and one self-cured GIC, and to observe the effect with an AFM of the four different conditioners on the surface of polished human dentine. MATERIALS AND METHODS: SAMPLE PREPARATION FOR FE-SEM: Twenty-four 1-mm thick dentine discs were obtained from superficial occlusal dentine of extracted human third molars, and finished with wet 600-grit SiC paper. The discs were treated for each of the GICs using the conditioners according to the manufacturers' instructions. The specimens were kept in tap water for 24 h at 37 degrees C, and then assigned for one of two observational techniques; a fractured technique and an acid-base technique. Specimens were mounted on aluminium stubs, gold sputter-coated and observed using a FE-SEM. SAMPLE PREPARATION FOR AFM: Four rectangular dentine blocks approximately 2mm(3) were prepared from two extracted human third molars, polished and finished with diamond paste down to 0.25 microm particle size. One half of each sample was treated with one of the conditioners according to the manufacturers' instructions, and the other half was not conditioned. The samples were stored in distilled water prior to AFM contact mode observation. RESULTS: FE-SEM: All specimens of all materials demonstrated good adaptation to the underlying dentine. However, the specimens conditioned with K-930 showed increased demineralization and a thicker acid-base resistant layer (2.8-3.4 microm) compared with the others (1-2 microm). AFM: The images of conditioned specimens showed demineralization of peritubular dentine. Funneling of dentinal tubule orifices of specimens conditioned with K-930 was observed, and was also seen for the FE-SEM specimens. SIGNIFICANCE: The use of surface conditioners resulted in similar adaptation to the non-conditioned specimens at the GIC-dentine interface. All of the GICs demonstrated intimate adaptation to the dentine surface whether it was conditioned or not.

Acid Etching, Dental↗

PubMed2001

Shear bond strengths of three resin cements to dentine over 3 years in vitro.

OBJECTIVES: This study was conducted to evaluate the bond durability of three resin cements bonded to bovine dentine over a period of 3 years. METHODS: Ten bovine dentine specimens were tested for shear bond strengths with each of the following materials: Panavia 21, BISTITE resin cement, and MASA Bond (experimental resin cement) at 1 day, 6 months, 1 and 3 years after cementation of a composite rod. All specimens were stressed in shear at a crosshead speed of 1mm min(-1) until failure. The means of the bond strengths were compared statistically by two-way ANOVA and Fisher's PLSD test (P<0.05). The mode of failure was classified after fracture of the bonds by SEM observation. Results for the mode of fracture were analyzed using the Mann-Whitney U-test. RESULTS: The shear bond strengths (MPa+/-SD) for different times (1 day, 6 months, 1 and 3 years) were: Panavia 21 (15.2+/-3.6, 9.3+/-3.2, 8.5+/-2.1, 6.8+/-2.4), BISTITE (15.6+/-2.8, 11.0+/-1.4, 10.4+/-2.2, 9.0+/-2.7) and MASA Bond (29.6+/-9.5, 17.5+/-4.6, 19.6+/-4.5, 16.1+/-5.4). Panavia 21 and BISTITE strengths were significantly lower (P<0.05) at all times compared with MASA Bond, and 1 day strengths for all three materials were significantly higher (P<0.05) than 3 year strengths. Regarding the fracture modes after bond testing, there were statistical differences between the 1 day and the 1 year results for all cements (P<0.05). Although no Panavia 21 specimen showed complete cohesive failure in the demineralized dentine during the experiment, several BISTITE and MASA Bond specimens showed cohesive fracture in the demineralized dentine. For BISTITE, partially or complete demineralized dentine cohesive failures increased over time. CONCLUSIONS: The type of resin cement seemed to have an influence on the long-term durability of bonding to dentine.

Analysis of Variance↗

PubMed2001

The microtensile strength of bonding resins.

BACKGROUND: The purpose of this study was to determine the effect of water on the tensile strength of three bonding resins (All Bond 2, Scotchbond Multi-Purpose Adhesive, Clearfil LB Bond) and a low viscosity resin composite (Protect Liner F) after 1, 7, 28, 84 and 168 days of storage. METHODS: Cylinders of bonding resin 2.4 +/- 0.2 mm diameter and 9.5 mm long were made and stored at 37 degrees C for 24 hours. The specimens were milled into dumb-bell shapes and stored in either air or water at 37 degrees C. Five specimens of each material were stressed in tension after the specified storage times at a crosshead speed of 1 mm/min in a testing jig attached to a universal testing machine. The mean tensile strengths of bonding resins were calculated and analysed statistically using one-way analysis of variance, lower standard deviation and student t-tests. RESULTS: Comparison of the air and water samples at all test periods showed the tensile strengths of specimens stored in water were significantly less than those stored in air (P < 0.001). CONCLUSION: The effect of water on the tensile strength of bonding resins indicated a slight decrease in strength of each material over the 168 day test period, whereas the air samples showed little change over the test period.

Analysis of Variance↗

PubMed2001

Pits and fissures: etch resistance in prismless enamel walls.

BACKGROUND: In a previous study to examine the nature of etching on the walls of fissures, there was a consistent result of resistance to deep etching on parts of the walls and a zone of lesser etching on part of the walls as evidenced by the uptake of stain. The staining had been used to examine the nature of the etch pattern. The aims of this study were to define the nature of this etch resistant area. METHODS: A sample of 55 teeth, both molars and premolars, were divided into three groups. In the first group the wetting of fissures by the etchant was examined; the second group tested for the effects of pellicle-cuticle-debris or air entrapment on the etching process. The final group looked at alternative mechanical treatments of the fissure prior to etching. RESULTS: The specimens split along the fissures showed clearly that the etch resistant zone was not due to lack of contact with the etchant or the presence of a pellicle-cuticle-debris covering, but to the presence of a prismless enamel structure. This study showed that this zone inhibited tag development on the fissure walls. CONCLUSIONS: The mechanical removal of this prismless layer of enamel within the fissure system should result in an improved bonding of a fissure sealant through better tag development, in turn leading to a reduction in the failure rate of a sealant used to prevent caries.

Acid Etching, Dental↗

PubMed2001

The effects of bonding system and light curing method on reducing stress of different C-factor cavities.

PURPOSE: The effect of the slow-start curing method on the marginal sealing and cavity wall adaptation on resin composite restorations with different C-factors was evaluated. METHODS: Cylindrical cavities, 1 mm deep and 3 mm in diameter (C-factor=2.3) or 2 mm in diameter (C-factor=3) were prepared on flat superficial bovine dentin surfaces. The teeth were restored with Clearfil Photo Bond, Clearfil Liner Bond 2 or Super-Bond D Liner adhesive systems followed by Photo Clearfil Bright composite. The resins were cured with a conventional method using 600 mW/cm2 (tip-to-resin distance 0 mm) for 60 s, or the slow-start curing method of 270 mW/cm2 (tip-to-resin distance 10 mm) for 10 s, followed by a 5-s interval, then 50 s at 600 mW/cm2. After thermocycling, a dye penetration test was carried out. The dye penetration length was calculated as a percentage of the total cavity wall length. RESULTS: Cavity-wall gap formation increased when the C-factor increased from 2.3 to 3, except in one material, Super-Bond D Liner, which showed good marginal sealing and resin composite adaptation to the cavity wall regardless of light curing method and C-factor. CONCLUSION: It is necessary to take care when a cavity with a high C-factor is to be restored with resin composite. The combination of a flexible adhesive and the slow-start curing method would seem to be effective in reducing polymerization contraction stress for large C-factor cavities.

Analysis of Variance↗

PubMed2000

Fluoride release from glass ionomer cements and resin composites coated with a dentin adhesive.

OBJECTIVES: This laboratory study compared the effect of surface coatings on patterns and amounts of fluoride released from four glass ionomer cements and two fluoride-containing resin composites. METHODS: Twelve cylinders of each material were prepared in a polyethylene mold. The experimental groups (n = 6) were coated with one layer of an adhesive resin (3M Scotchbond Multipurpose Adhesive), while the control groups (n = 6) remained uncoated. Cumulative fluoride release into deionized water was measured on days 1, 2, 3, 7, 14, 21 and 28 using an ion analyzer. Total fluoride release after 28 days was analyzed for significant differences among materials using one-way ANOVA and Student-Newman-Keuls test (p < 0.05). RESULTS: The total amounts of fluoride release from the coated samples were found to be significantly less than the uncoated samples for all materials, except Solitaire. The uncoated samples released a total amount of fluoride of between 2.3 and 85.4 ppm, while the coated samples released a total amount of fluoride of between < 0.2 and 24.1 ppm. Similar patterns of fluoride release were found in coated and uncoated samples. SIGNIFICANCE: The results indicated that the application of a dentin adhesive coating did not completely prevent fluoride release from glass ionomer cements and fluoridated resin composites, although the amounts were significantly less. Clinically, it suggests that a continued release of fluoride from glass ionomer cements and fluoridated resin composites is possible after placing a thin layer of resin adhesive. The clinical significance of these findings is not known.

Analysis of Variance↗

PubMed2000

Microtensile bond strengths of seven dentin adhesive systems.

OBJECTIVES: The purpose of this study was to evaluate the microtensile bond strengths of seven dentin adhesive systems (Solid Bond, EBS-Multi, PermaQuik, One Coat Bond, Gluma One Bond, Prime & Bond NT/NRC and Clearfil Liner Bond 2V) and their respective fracture modes. METHODS: Superficial occlusal dentin of extracted human molars was exposed, finished with wet 600-grit silicon carbide paper, and a block of resin composite bonded with the above adhesives according to the manufacturers' instructions. The teeth were kept in tap water for 24 h at 37 degrees C, sectioned to obtain three or four bar-shaped specimens, which were then shaped to an hour-glass form of 1.2 +/- 0.02 mm diameter. The specimens were stressed at a crosshead speed of 1 mm/min until rupture of the bond. The mean bond strengths were compared using one-way ANOVA and LSD tests. The frequency of fracture modes was compared using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Mean microtensile bond strengths ranged from (17.8 +/- 7.0) MPa for Solid Bond to (36.0 +/- 8.1) MPa for Clearfil Liner Bond 2V. The bond strength of Clearfil Liner Bond 2V and PermaQuik (30.8 +/- 8.5 MPa) were not significantly different, and were higher than all other materials. Bond strengths of Solid Bond (17.8 +/- 7.0) MPa, EBS-Multi (18.7 +/- 5.0) MPa, One Coat Bond (21.9 +/- 5.6) MPa, and Gluma One Bond (23.4 +/- 5.2) MPa were not significantly different. SEM examination indicated that Solid Bond, EBS-Multi and One Coat Bond showed no significant difference in failure modes but were significantly different from PermaQuik, Prime & Bond NT/NRC and Clearfil Liner Bond 2V. SIGNIFICANCE: The self-etching primer system, Clearfil Liner Bond 2V, provided the simplest bonding technique, and together with PermaQuik exhibited greatest bond strength to dentin.

Analysis of Variance↗

PubMed2000

The influence of the modification of etched bovine dentin on bond strengths.

OBJECTIVE: The aim of this study was to modify demineralized bovine dentin surfaces by application of either 12.5% sodium hypochlorite (NaOCl), or 0.1% (w/w) Type I collagenase, after conditioning with phosphoric acid, to observe the demineralized surface and to investigate the effect on tensile bond strength. METHODS: The NaOCl was applied to etched dentin for 30 s, 1 or 2 min and the collagenase for 1, 3 or 6 h. A control group was used without NaOCl or collagenase treatment. Prior to bonding, treated surfaces were examined using an Atomic Force Microscope (AFM). A 2.3 mm diameter area of dentin was conditioned, treated and bonded with either One Coat Bond or Single Bond following each manufacturer's instructions, and a resin composite rod attached. Bonds were stressed in tension at a rate of 1 mm/min until failure. Mean bond strengths were calculated (MPa) and mode of failure was determined by observation at 20x magnification. Results were analyzed using multiple regression analysis and LSD test at the 95% level of confidence (n = 12). RESULTS: AFM results showed progressive changes of the surface collagen as the treatment time of NaOCl or collagenase increased. For both bonding systems, the bond strengths of 1 min NaOCl and 3 h collagenase treatments were significantly higher than the control or other treatment groups (p < 0.05). Bond failure consisted of mostly adhesive failure between dentin and resin combined with small regions exhibiting cohesive failure of resin. SIGNIFICANCE: Bond strengths were not dependent on the thickness of the hybrid layer, but rather quality of the hybrid layer.

Acid Etching, Dental↗

PubMed2000

The influence of storage solution on dentin bond durability of resin cement.

OBJECTIVES: This study was conducted to determine the influence of storage solution on the bond durability of three resin cements to bovine dentin over the period of 1 year. METHODS: Ten bovine dentin specimens were tested for shear bond strength with each material (Panavia 21, Kuraray Co.; BISTITE, Tokuyama Co; MASA Bond, Sun Medical Co.) and storage mode, listed below. Four storage environments were studied as follows: water changed every day for 1 year; water unchanged for 1 year; Phosphate Buffered Saline (PBS) changed every week over 1 year; PBS unchanged for 1 year. Ten teeth were also tested for each material at 1 day as a control. The mode of failure was classified after fracture of the bonds by SEM observation. The means of the bond strengths were compared statistically by two-way ANOVA and Fisher's PLSD test (p < 0.05). Results for the mode of fracture were analyzed using the Mann-Whitney U test. RESULTS: Although there was no statistical difference in the mean bond strengths between the water and PBS storage solutions (p > 0.05) in all cements, the results for the shear bond strengths in the changed storage solution groups were significantly lower than those where the storage solution remained unchanged (p < 0.05). There were statistical differences between the 1 day results and the changed water groups among all cements (p < 0.05). SIGNIFICANCE: The storage condition influenced the long-term durability of dentin bonding with resin cements.

Adhesiveness↗

PubMed2000

Nanoleakage patterns of four dentin bonding systems.

OBJECTIVES: The purpose of this study was to evaluate the nanoleakage patterns of four dentin bonding systems. METHODS: The dentin bonding systems used in this study were: Single Bond, One Coat Bond, Prime & Bond NT/Non Rinse Conditioner (NRC), and PermaQuik. Flat occlusal dentin surfaces from extracted human molars were finished with wet 600-grit silicon carbide paper, and bonded with one of the dentin bonding systems. After 24 h storage at 37 degrees C in water, margins were finished with polishing discs and the surrounding tooth surfaces coated with nail varnish. The samples were immersed in a 50% (w/v) solution of silver nitrate for 24 h, and exposed to photodeveloping solution for 8 h. The samples were cut longitudinally, polished, and mounted on stubs, carbon coated and observed in a Field Emission-SEM using backscattered electron mode. RESULTS: Different nanoleakage patterns were observed with the different adhesive systems. However, accumulations of silver particles were often noted at the base of the hybrid layer for all materials. Single Bond and One Coat Bond demonstrated uptake of silver particles both within the hybrid layer and the adhesive resin. Prime & Bond NT/NRC showed silver staining throughout almost the entire thickness of the hybrid layer. The leakage pattern of PermaQuik revealed loose silver deposition within the hybrid layer. The composition of each adhesive system may play a role in forming the different leakage patterns. SIGNIFICANCE: The current dentin bonding systems used in this study do not achieve perfect sealing at the restoration/dentin interface, which may influence the durability of the bond to dentin.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2000

Microtensile bond strengths of glass ionomer (polyalkenoate) cements to dentine using four conditioners.

OBJECTIVES: The purpose of this study was to measure the microtensile bond strengths of three glass ionomer cements to dentine (Photac-Fil Quick; Fuji II LC; Fuji IX GP) using four different conditioners (Ketac Conditioner; Dentin Conditioner; Cavity Conditioner; and an experimental conditioner, K-930). METHODS: Superficial occlusal dentine of extracted human third molars was exposed, finished with wet 600-grit silicon carbide paper, and each of the above glass ionomer cements bonded using the four conditioners according to the manufacturers' instructions. After 24h in tap water at 37 degrees C, the teeth were sectioned to obtain 3-4 bar-shaped specimens. Ten specimens were prepared for each group and shaped to an hour-glass form of (1.2+/-0.02)mm diameter. The specimens were mounted in a jig and stressed in tension at a crosshead speed of 1mm/min until failure. The mean bond strengths were calculated and compared using one-way ANOVA and LSD tests, and the fracture modes were examined by scanning electron microscopy. RESULTS: Mean microtensile bond strengths for Photac-Fil Quick were not significantly different from Fuji II LC for each of the conditioners used. However, the bond strengths for Photac-Fil Quick were significantly greater than Fuji II LC when no conditioner was applied. Mean microtensile bond strengths of conditioned specimens of Fuji II LC were significantly greater than non-conditioned specimens. Mean microtensile bond strengths of non-conditioned specimens of Fuji IX GP were not significantly different from conditioned specimens. The fracture mode of all specimens demonstrated mostly cohesive failure within the cement. SIGNIFICANCE: The use of surface conditioners resulted in improvement in bond strength of Fuji II LC, while Photac-Fil Quick and Fuji IX GP showed no difference.

Acrylic Resins↗

PubMed2000

Clinical evaluation of EBS dentine bonding agent: one year results.

There are numerous dentine bonding agents currently on the market, the majority of which adhere by means of infiltration of a hydrophilic polymerizable diacrylate into dentinal collagen exposed by acid treatment. The purpose of the present study was to evaluate the clinical performance of one such product, EBS dentine bonding, in non-undercut caries-free cervical lesions. Forty cavities were restored in eight patients of mean age 53 years. The manufacturer's instructions were followed, which involved essentially etching the enamel and dentine for 20 seconds with 32 per cent phosphoric acid, application and evaporation of EBS Primer, followed by placement and curing of EBS Bond, and restoring the cavity with Pertac II (ESPE) hybrid resin composite. Restorations were photographed at base line and one year for evaluation of marginal discolouration on a continuous linear rating scale. At six months, one patient with four restorations was not available; the remaining 36 restorations were all present. At one year, one restoration was missing, giving a cumulative retention rate of over 97 per cent. One of the 36 restorations exhibited very mild marginal discolouration.

Acid Etching, Dental↗

PubMed2000

Field-emission scanning electron microscopy of resin-dentin interface morphology of seven dentin adhesive systems.

PURPOSE: The purpose of this study was to evaluate the resin-dentin interface morphology of 7 resin-based dentin adhesive systems (Solid Bond, EBS-Multi, PermaQuik, One Coat Bond, Gluma One Bond, Prime & Bond NT/NRC, and Clearfil Liner Bond 2V). MATERIALS AND METHODS: Fourteen dentin disks 1.0 mm thick were obtained from superficial occlusal dentin of extracted human third molars, and finished with wet 600-grit silicon carbide paper. Two dentin disks were bonded using each of the adhesives above according to the manufacturers' instructions, and a thin layer of flowable resin composite was applied. The specimens were kept in tap water for 24 h at 37 degrees C, and then assigned to one of two observational techniques: a fracture technique and an acid-base technique. Fracture technique: shallow grooves were cut, fixed in 10% buffered formalin, and dehydrated in an ascending ethanol series up to 100%, critical-point dried, and fractured along the prepared grooves. Acid-base technique: the specimens were embedded in epoxy resin, sectioned through the center, polished with diamond paste down to 0.25-micron particle size, and treated with 10% orthophosphoric acid for 10 s and 5% sodium hypochlorite for 5 min. All the specimens were mounted on aluminum stubs, gold sputter coated, and observed using field-emission scanning electron microscopy (FE-SEM). RESULTS: All the dentin adhesive systems showed hybrid layer formation, but the thickness varied depending on the bonding system used. The self-etching priming systems (Prime & Bond NT/NRC and Clearfil Liner Bond 2V) showed the thinnest hybrid layer at 1 to 2 microns, whereas the "single-bottle" system (Gluma One Bond) exhibited the thickest hybrid layer at 8 to 16 microns. CONCLUSION: The ultramorphological structures of dentin bonding systems are determined by the composition of each system. Characterization of the interface of the adhesive system using the fracture technique provides additional information regarding the pattern of resin infiltration in some dentin bonding systems.

Adhesives↗

PubMed2000

Micromorphological investigation of noncarious cervical lesions treated with demineralizing agents.

PURPOSE: The purpose of this study was to examine the micromorphology of noncarious cervical lesions (NCCL) and the change occurring after acid conditioning. MATERIALS AND METHODS: Nine wedge-shaped lesions, 9 saucer-shaped lesions, and 5 third molars with prepared cervical cavities were used. All NCCLs exhibited a hard, smooth surface with no discoloration. The teeth were sectioned and divided into three groups, each containing the three lesion types. Teeth in Group I were not etched, and teeth in Groups II and III were etched with 35% phosphoric acid and 20% polyacrylic acid/3% aluminum chloride, respectively. Field emission SEM and atomic force microscopy were used to examine the lesion surfaces. RESULTS: The surfaces of the prepared cervical (control) lesions were covered with a smear layer. Treatment with phosphoric acid and polyacrylic acid resulted in removal of the smear layer, although some residual smear layer was found on the surface treated with polyacrylic acid. The images of the untreated surfaces of NCCL showed highly mineralized dentin with complete obliteration of the dentinal tubules. After treatment with phosphoric and polyacrylic acids, the images revealed demineralization of the surface, which was more pronounced on those treated with phosphoric acid. CONCLUSION: The mineral deposits on the surface of NCCL decreased the effect of acid conditioning. Although there was no apparent difference between the two forms of NCCL used in this study, further work is needed to better understand these lesions.

Acid Etching, Dental↗

PubMed2000

Nanoleakage of cervical restorations of four dentin bonding systems.

PURPOSE: The aim of this study was to evaluate the degree of nanoleakage of restorations placed in cervical preparations with dentin bonding systems. MATERIALS AND METHODS: The dentin bonding systems used were Single Bond, One Coat Bond, Prime & Bond NT/NRC, and PermaQuik. Ten saucer-shaped cervical preparations were bonded with one of the dentin bonding systems and restored with Silux Plus resin composite in each group. After 24 hours storage in 37 degrees C water, restorations were finished and the surrounding tooth surfaces were coated with nail varnish. The samples were immersed in 50% w/v solution of silver nitrate for 24 hours, and exposed to photodeveloping solution for 8 hours. The samples were cut longitudinally through the center, polished, carbon coated and observed in a Field Emission SEM using backscattered electron mode. The degree of silver penetration along the preparation wall was observed and calculated as a percentage of the total preparation wall length. Results were analyzed by one-way ANOVA and LSD tests. RESULTS: PermaQuik demonstrated the lowest leakage score and the least silver deposition within the hybrid layer, while Prime & Bond NT/NRC showed the greatest leakage scores and the most silver deposition within the hybrid layer. Different nanoleakage patterns were observed for the different adhesive systems. CONCLUSION: First, the composition of each adhesive system may play a role in the different leakage patterns. Second, the current dentin bonding systems used in this study did not achieve perfect sealing at the restoration-dentin interface. This may influence the durability of the bond to dentin.

Acid Etching, Dental↗

PubMed1999

Effect of intrinsic wetness and regional difference on dentin bond strength.

OBJECTIVES: The aim of this investigation was to determine the influence of intrinsic wetness on regional bond strengths of adhesive resins to dentin. METHODS: Human caries-free third molars were randomly divided into three groups for bonding: Group 1--no pulpal pressure; Group 2--pulpal pressure of 15 cm H2O; and Group 3--dentin dried overnight in a desiccator. Clearfil Liner Bond II (Kuraray) or One Step (Bisco) adhesive resins systems were applied to the flat dentin surfaces and the teeth were restored with APX resin composite (Kuraray). After 24 h in water at 37 degrees C, the specimens were sectioned into 0.7 mm thick slabs and divided into three regional subgroups according to the remaining dentin thickness and visual criteria: pulp horn, center, and periphery. The slabs were then trimmed for the micro-tensile bond test and subjected to a tensile force and crosshead of 1 mm/min. The data were analyzed with ANOVA and Fisher's PLSD test at a confidence level of 95%. The fracture modes were determined under a scanning electron microscope (JXA-840, JEOL, Japan). RESULTS: No significant regional difference was observed for the Group 1 and 2 specimens restored with Clearfil Liner Bond II (p > 0.05). However, bond strengths significantly decreased at the pulp horn region of the Group 1 and 2 specimens restored with One Step (p > 0.01). All bond strengths of Group 3 decreased significantly and regional differences were not evident (p > 0.05). SIGNIFICANCE: The dentin adhesive system should be chosen according to the substrate and region to be bonded, since bond strengths can vary according to the intrinsic wetness, region, and the adhesive system.

Dental Bonding↗

PubMed1999

The effect of dentine location and tubule orientation on the bond strengths between resin and dentine.

This study determined the influence of dentine structure on the micro-tensile bond strengths between resin and dentine of two different dentine adhesive systems (Single Bond, 3M Dental Products, St Paul, MN; MF-102 (experimental self-etching primer), GC Corporation, Tokyo, Japan). The study was separated into two main parts: bond strength measurement and investigation of the bonding interface. Twenty-two human premolars were used for the bond strength measurement. Each tooth was cut vertically, separating the tooth into mesio-distal halves. One half of the tooth was used to bond to a surface perpendicular to the dentinal tubules and other half to bond to a surface parallel to the tubules. For each half, six locations of dentine were bonded. Each material was used in accordance to the manufacturer's directions. Cylindrical hourglass-shaped specimens of 1.2 mm diameter at the bonded interface were manufactured. The bonds were stressed in tension at a crosshead speed of 1 mm/min. Mean bond strengths were compared using LSD, one-way ANOVA, and Student's t-test. The fractured surfaces were examined under a scanning electron microscope, and the frequency of fracture modes was compared using the Kruskal-Wallis and Mann-Whitney U tests. For the investigation of the bonded interface, four teeth were prepared by the same procedure used for the bond test specimens. The bonded interfaces were observed after an acid-base treatment or fracturing across the bonded interface, prior to investigation with a field-emission scanning electron microscope. For Single Bond, the bond strengths for mid-root dentine were significantly lower than for other locations (p < 0.05). For MF-102, there was no significant difference for all locations (p > 0.05). MF-102 bonded well to all locations of dentine while Single Bond showed a porous zone at the base of the hybrid layer. The bonds were not influenced by tubule orientation. The results indicate that the bond for Single Bond may be affected by its ability to penetrate demineralised dentine in different locations of a tooth. The self-etching primer of MF-102 produces a good bond and is independent of the position on the tooth.

Analysis of Variance↗