Biomedical subjects

M F Burrow

Publications and source records attributed to M F Burrow.

At least 55 records · Page 3Linked to original sources

PubMed1999

Effects of dentin depth and cavity configuration on bond strength.

During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that develops in cavities with high C-factors.

Analysis of Variance↗

PubMed1999

Bond strengths to endodontically-treated teeth.

PURPOSE: To evaluate the bond strengths of three different types of resin bonding systems to teeth prepared for endodontic treatment. MATERIALS AND METHODS: Access cavity preparation and removal of pulpal tissue were performed in bovine incisors. The root canals were chemically irrigated with saline (control), 5% sodium hypochlorite, 3% hydrogen peroxide, or combinations of both for 60 s. After storage in water for 1 d, the dentin surface was ground to a flat surface with 600-grit SiC under water. The area for bonding was demarcated with a vinyl tape (4 mm-in-diameter hole), and bonded using either Clearfil Liner Bond II, Single Bond, or Superbond C&B. After storage in 37 degrees C water for 1 d, tensile bond strengths were measured using a universal testing machine at a crosshead speed of 2 mm/min. Ten teeth were tested for each group. RESULTS: One-way ANOVA and Fisher's PLSD test revealed that Single Bond and Superbond C&B had a statistically lower (P < 0.05) bond strengths in the chemical irrigation groups compared with the control group.

Animals↗

PubMed1999

1-year clinical evaluation of one-step in non-carious cervical lesions.

PURPOSE: To evaluate the 1-year clinical retention rate of restorations of non-carious cervical lesions placed using a "one-bottle" adhesive (One-Step) and one of two low modulus resin-based composite (RBC) restorative materials (AEliteflo or Bisco Glaze) or a microfilled RBC (Silux Plus). MATERIALS AND METHODS: 105 non-carious cervical lesions in 14 patients, mean age 60 years, were restored using either AEliteflo, Bisco Glaze or Silux Plus with One-Step dentin bonding agent. The dentin surface was lightly roughened with a fine diamond stone, cleaned with pumice and water and restored according to the manufacturers' instructions. Patients were recalled at 6 months and 1 year, and the restoration sites examined. RESULTS: At 6 months all restorations were present. At 1 year, five restorations were missing (two Silux, three AEliteflo), three of which were in one patient. A cumulative retention rate of 95% was recorded. A small number of restorations exhibited marginal discoloration, but this was believed to be due to excess RBC on unetched enamel.

Adult↗

PubMed1999

Water sorption of several bonding resins.

PURPOSES: To determine, over the period of 1 month, (a) the degree of water sorption, and (b) the change in dimension, of four bonding resins and one low viscosity resin. MATERIALS AND METHODS: Six specimens of bonding resin (Prisma Universal Bond 3, All-Bond 2, Bondwell LC, and LB Bond from the Clearfil Liner Bond II system) and a low viscosity resin (Protect Liner F) measuring 5 mm long, 5 mm wide and 3 mm thick were made. Each specimen was weighed immediately after curing and placed in distilled water at 37 degrees C. Weights at 1, 2, 3, 7 days and 2, 3 and 4 weeks were obtained. Specimens were measured initially and at the above times. After 4 weeks, specimens were dried for 2 weeks and remeasured for size and weight. Then, the specimens were placed in a vacuum for approximately 4 hours and the weights and dimensions were remeasured. Values were converted to a mean percentage of the original dry weight and dimension and analyzed using one-way ANOVA and Fisher's PLSD test. RESULTS: All materials absorbed most water in the first week. Prisma Universal Bond 3 stabilized within 2 days, LB Bond stabilized within the first week, whereas the remaining materials showed statistical increases in weight for 2-3 weeks (P < 0.05). After 4 weeks, LB Bond and All-Bond 2 resins demonstrated an approximate 8% weight increase, and the least increase was observed for Protect Liner F and Prisma Universal Bond 3 at about 3%. After desiccation, Protect Liner F and All-Bond 2 returned close to their original weight, and the remainder weighed less than initially. Dimensional changes were similar to changes in weight; LB Bond showed the greatest dimensional change over the 4 weeks (5%) and Protect Liner F the least change.

Analysis of Variance↗

PubMed1998

Effect of cross-sectional surface area on bond strengths between resin and dentin.

OBJECTIVES: This study was conducted to determine the effect of the bonding area on the micro-shear and micro-tensile bond strengths of four dentin adhesive systems (Scotchbond MP Plus, 3M Dental Products, St. Paul, MN; OptiBond FL, Kerr Corp., Orange, CA; OptiBond Solo, Kerr Corp., Orange, CA; One-Step, Bisco, Inc., Itasca, IL). METHODS: Sixty extracted human molars were cut vertically and occlusal enamel removed, one half of the tooth was used for tensile testing and one half for shear. The occlusal dentin was bonded according to manufacturers' directions with a resin composite block and sectioned to obtain up to three square bar-shaped specimens, which were shaped with a high speed diamond bur on a lathe to produce cylindrical specimens of 1.2, 1.4 or 2.0 mm diameter at the bonded interface. The bonds were stressed in shear or tension at a crosshead speed of 1 mm min-1. The mean bond strengths were compared using one-way ANOVA, two-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. RESULTS: For all materials, the 2.0 mm diameter group showed significantly lower bond strengths than the 1.2 mm diameter group in both shear and tensile tests (p < 0.05). Most specimens of 1.2 mm or 1.4 mm diameter exhibited adhesive failure at the interface between the dentin and the adhesive resin. SIGNIFICANCE: The results indicate that small surface areas of test specimens are associated with higher bond strengths and that the effect on tensile and shear values is similar.

Analysis of Variance↗

PubMed1998

The influence of cross-sectional shape and surface area on the microtensile bond test.

OBJECTIVES: The purpose of this study was to determine the effect of the cross-sectional area shape (cylindrical vs. rectangular) and the bonding surface area on the microtensile bond strengths and stress distribution of four dentin adhesive systems (Scotchbond MP Plus, OptiBond FL, OptiBond Solo, One-Step). In addition, finite element analysis (FEA) models were developed to investigate stress distributions. METHODS: Extracted human molars were cut vertically and the occlusal enamel removed; one-half of the tooth was used for rectangular specimens, the other half for cylindrical specimens. The occlusal dentin was bonded according to the manufacturers' directions and covered with a block of resin composite. For the cylindrical specimens, the bonded dentin was shaped with a diamond bur on a lathe to produce specimens of area 1.1, 1.5 or 3.1 mm2 at the bonded interface. The rectangular specimens were sectioned to obtain bar-shaped specimens, which were shaped to produce hour-glass shaped specimens with the same area as the round specimens. Bonds were stressed in tension at a speed of 1 mm min-1. The mean bond strengths were compared using two-way ANOVA, one-way ANOVA, LSD and Student's t tests. The fractured surfaces were examined by scanning electron microscopy, and the frequencies of the fracture modes were compared using the Kruskal-Wallis and Mann-Whitney U tests. FEA models were created simulating the cross-sectional areas for bonding to determine the stress distribution. RESULTS: The 3.1 mm2 bonding area groups showed significantly lower bond strengths than the 1.1 mm2 bonding area groups (p < 0.05), except for the rectangular specimens using Scotchbond MP Plus and One-Step. Most cylindrical specimens of bonding area 1.1 or 1.5 mm2 exhibited adhesive failure at the interface between the dentin and the adhesive resin. No differences were determined between cylindrical and rectangular specimens. The fracture mode matched the stress distribution patterns calculated from the FEA modeling. SIGNIFICANCE: The results indicate that the test methods using small surface areas produce higher bond strengths than those using larger surface areas, and that cross-sectional shape has little effect. This is probably a result of fewer defects occurring in the small-area specimens.

Analysis of Variance↗

PubMed1998

Effect of operator variability on dentin adhesion: students vs. dentists.

The purpose of this study was to evaluate the operator variability of two dentin bonding systems. Fourteen undergraduate students and ten dentists of different levels of clinical experience were selected. Tensile bond strengths between resin composite and bovine dentin using dentin adhesive systems (Clearfil Liner Bond II: LB II; Scotchbond Multi-Purpose: MP) bonding systems showed a large scatter among students and dentists. The dentists group demonstrated no statistically significant differences for mean bond strengths between LB II and MP. The student group recorded a statistically greater bond strength using LB II. The mean coefficient of variation of the dentists group showed no statistically significant difference between LB II and MP, however that of the students group was lower with LB II. When using MP, the dentist group demonstrated a lower coefficient of variation than that of the student group. In order to obtain optimal bonding performance, or when beginning the use of a new system, the operator should be aware of the technique sensitivity of some adhesive systems and sensitivity to operator variability.

Analysis of Variance↗

PubMed1996

Dentin bond durability after three years using a dentin bonding agent with and without priming.

OBJECTIVES: This three-year study was conducted to evaluate the tensile bond strengths of a dual-cured bonding resin, with and without priming, to bovine dentin. METHODS: Superficial bovine dentin was conditioned with 37% phosphoric acid and left unprimed (control) or was primed with 5-NMSA. Clearfil Photobond (Kuraray Co., Japan) was placed and light-cured, a layer of Protect Liner (Kuraray Co.) was applied, cured, then covered with Photo Clearfil Bright (Kurary Co.) resin composite and cured. Bonds were stressed in tension to failure at 1 d, 1 mon, 3 mon, 6 mon, 1 y and 3 y after preparation. Ten specimens were made for each group. Results were analyzed using one-way ANOVA and Duncan's multiple range test. Visual and SEM observations determined mode of failure and were analyzed using the Mann-Whitney U-test. Separate 1 d and 3 y specimens were fractured across the bonded interface and observed using a Field Emission SEM. After observation, the photomicrographs were compared for visual qualitative changes between the two time periods. RESULTS: The control (non-primed) group showed only a small decrease in bond strengths over 3 y, but in the primed group, a significant decrease was observed (p < 0.05). The bond strength of the non-primed group (5.2 MPa) was less than the primed group (10.6 MPa) at 1 d (p < 0.01), but by 3 y, the bonds of both groups were similar, 4.3 MPa and 5.5 MPa, respectively. Fractography indicated that only adhesive failure occurred in the control group. Failure in the primed group was cohesive in dentin initially, but shifted to the base or top of the hybrid layer after 1 y. Field Emission SEM observations showed hybrid layer formation in the primed group, but minimal resin infiltration in the control group. SIGNIFICANCE: Initially greater bond strengths were obtained for the primed group compared to the unprimed group (p < 0.01). However, by 3 y, the bond strength had decreased markedly in the primed group (p < 0.01), being almost the same for both groups. It was concluded that priming may only be useful to achieve strong bonding in the short term. These results may have significant implications related to clinical longevity of restorations.

Analysis of Variance↗

PubMed1996

Accuracy of interpretation of microscopic images of cytologic, hematologic, and histologic specimens using a low-resolution desktop video conferencing system.

OBJECTIVE: To determine the accuracy of interpretation of microscopic images for pathologic study transmitted over Switched-56 lines using a desktop interactive video conferencing system. MATERIALS AND METHODS: In subjective studies, two systems were connected using null-modem cables, which allowed evaluation of different bandwidths from 56 kbps to 384 kbps. Objective studies were done with two systems connected at distant sites via paired Switched-56 lines that produced an effective bandwidth of 112 kbps. A video camera mounted on a microscope was attached to the sending system. The resolution of the video image on the video conferencing system was 352 x 288 lines. Cases for cytology, hematology, and histopathology studies were selected from archives; one pathologist transmitted microscopic images, and a second pathologist made interpretations. The three pathologists were Board certified with similar experience that ranged from 20 to 35 years. Categories of interpretations or observations were predetermined for each study to allow the data on agreement between the direct microscopic interpretation or observation and that recorded by the receiving pathologist to be corrected for agreement attributable to chance alone. The results were analyzed using the kappa statistic. RESULTS: In the subjective studies, image degradation prevented interpretation while the microscope stage was moved. This problem occurred at all bandwidths tested. Image quality limited microscopic details. Organisms < 1 micron in diameter could not be seen reliably. In objective cytologic studies, overall agreement was recorded on 89 of 99 observations. In the four categories of specimens, observed agreement ranged from 0.778 to 0.958, and kappa was 0.704 to 0.948. For hematology specimens, overall agreement was found on 69 of 80 observations; observed agreement on eight types of nucleated blood cells ranged from 0.5 to 1.0, and kappa was 0.429 to 1.0. Poorer color definition and image quality prevented accurate identification of lymphoblasts and eosinophils in particular. For histologic specimens, overall agreement was obtained on 56 of 66 observations, observed agreement on four categories of histologic change ranged from 0.73 to 0.93, and kappa was 0.47 to 0.9. CONCLUSIONS: The desktop interactive video conferencing system, as configured in this study, was unsuitable for making definitive diagnoses from transmitted microscopic images.

Cell Biology↗

PubMed1996

Bond strength to crown and root dentin.

PURPOSE: To investigate (1) the tensile bond strengths of four commercial dentin bonding systems to bovine crown and root dentin and (2) the structure of the hybrid layers for each system bonded to the two dentin substrates. MATERIALS AND METHODS: Superficial surfaces were exposed in bovine crown and root dentin. The teeth were embedded in plaster and a 3 mm diameter bonding area was demarcated. The four bonding systems used were All-Bond 2, Super-Bond D-Liner Plus, Clearfil Liner Bond II, and ProBond. Bonding procedures followed the manufacturers' instructions with the exception of Super-Bond D-Liner Plus where the primer was left in situ for 60 seconds. Tensile bond strengths were tested after 24-hour storage in 37 degrees C deionized water. Specimens were also prepared for SEM observation of the hybrid layer, after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite. RESULTS: Statistically lower bond strengths to crown dentin when compared with root dentin were observed for All-Bond 2, whereas Liner Bond II showed the opposite (P < 0.01). Both ProBond and Super-Bond D-Liner Plus showed no statistical differences between crown and root dentin (P > 0.05). Hybrid layers could be observed for All-Bond 2, Liner Bond II and Super-Bond D-Liner Plus, with no apparent differences between the hybrid layers of crown and root dentin. In the case of ProBond, where the smear layer was not removed during the priming stage, it appeared that the primer had infiltrated and caused hybridization of the smear layer. The differences in bond strength were thought to be related to the different bonding mechanisms of each material, as well as possible variations in the crown and root dentin substrates.

Acid Etching, Dental↗

PubMed1995

Shear and tensile bond testing for resin cement evaluation.

OBJECTIVES: The aim of this study was to compare the tensile and shear bond strengths of one experimental and four commercially available resin cements following the ISO document TR 110405 for bond measurement. METHODS: Tensile and shear bond tests were performed using bovine enamel and dentin as the tooth substrate with each of the resin cements. Resin composite rods were cemented to the prepared tooth surfaces. The bond strengths were obtained 24 h after cementation, and mode of failure was classified after fracture of the bonds, both visually and by SEM observation. RESULTS: Significant differences existed between the two bond test methods for all materials with enamel and three of the five cements when bonded to dentin. The shear test results were always the higher of the two test methods. Mode of fracture varied little for the visual classification, but the morphology from SEM observations showed considerable differences. SIGNIFICANCE: Although there are deficiencies in the current test methods these may be outweighed by substrate variables. A test model should be designed to determine which stresses, tensile or shear, are the greatest for different types of restorations. With this information, the type of test selected could provide appropriate information before clinical trials are commenced.

Aminosalicylic Acids↗

PubMed1995

Effect of air-powder polishing on adhesion of bonding systems to tooth substrates.

OBJECTIVES: The air-powder polisher was introduced to provide a method to quickly remove stains and plaque. The purpose of this study was to evaluate what effect preparing teeth with an air-powder polisher (Air-flow 2, Shofu) has on bonding to enamel and dentin substrates. METHODS: The bonding systems used in this study were one-step etching/priming systems (KBT-5, Kanebo; and Clearfil Liner Bond II, Kuraray) and a two-step etching/priming system (Superbond D-Liner Plus, Sun Medical). Bovine enamel and dentin surfaces were prepared and finished with 600-grit silicon carbide paper. Then the surfaces were either not treated (control) or air-powder polished for 15 s. A 4-mm bonding area was demarcated, and the tooth substrates were bonded with the three bonding systems according to the manufacturers' instructions. Tensile bond strengths were measured 24 h after storage in water at 37 degrees C. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were performed on air-powder polished specimens to determine changes in the surface morphology and detect residual material from the air-powder polisher. SEM and transmission electron microscopic (TEM) observations of the interface between the bonding resins and dentin were performed to detect variations in the hybrid layers of the control and treated specimens. RESULTS: The results indicated that air-powder polishing did not influence the tensile bond strength to enamel, but adversely affected the tensile bond strength to dentin for the one-step systems, but not for the two-step system. Changes to the enamel surface after air-powder polishing were minimal, but an increase in surface roughness and complete removal of the smear layer were observed on dentin. SEM and TEM observations of the resin/dentin interface suggested that the air-powder polisher might cause superficial maceration of the collagen fibers on the dentin surface. This change may have decreased the ability of the etching/priming agents and bonding resin to penetrate into the dentin, which would have resulted in a poor quality hybrid layer. SIGNIFICANCE: For those systems that contain only an acidic primer for dentin conditioning, the use of air-powder polishing for surface preparation prior to restoration of dentin margin cavities is contraindicated because of the loss of reliable bonding.

Air Pressure↗

PubMed1995

Influence of temperature and relative humidity on early bond strengths to dentine.

The effect of temperature and relative humidity (RH) on the early tensile bond strengths to bovine dentine of two bonding systems (Liner Bond System, and Scotchbond Multi-purpose), and an experimental system (KB-110) were tested. Two environmental conditions, room temperature (23 degrees C/50% RH) and oral temperature (30 degrees C/80% RH), were used in a controlled temperature and humidity chamber. Bond strengths were recorded immediately after, 10 min and 24 h following light curing. The tensile bond strengths did not vary between the two test conditions, but the mode of fracture was observed to change. The 30 degrees C/80% RH condition exhibited a slightly greater degree of adhesive type failures compared with the 23 degrees C/50% RH group. This was particularly so for the experimental system, indicating that different bonding systems may be more or less sensitive to changes in RH and temperature. Failures occurred partially or totally within the resin composite at the early test times, and it was concluded that the bond strengths of the systems tested tended to exceed the early cohesive strengths of the resin composite.

Adhesiveness↗

PubMed1995

Tensile bond strength and SEM evaluation of caries-affected dentin using dentin adhesives.

Tensile bond strength measurements are commonly used for the evaluation of dentin adhesive systems. Most tests are performed using extracted non-carious human or bovine dentin. However, the adhesion of resins to caries-affected dentin is still unclear. The objectives of this study were to test the hypothesis that bonding to caries-affected dentin is inferior to bonding to normal dentin, and that the quality of the hybrid layer plays a major role in creating good adhesion. We used a micro-tensile bond strength test to compare test bond strengths made to either caries-affected dentin or normal dentin, using three commercial adhesive systems (All Bond 2, Scotchbond Multi-Purpose, and Clearfil Liner Bond II). For scanning electron microscopy, the polished interfaces between the adhesive bond and dentin were subjected to brief exposure to 10% phosphoric acid solution and 5% sodium hypochlorite, so that the quality of the hybrid layers could be observed. Bonding to normal dentin with either All Bond 2 (26.9 +/- 8.8 MPa) or Clearfil Liner Bond II (29.5 +/- 10.9 MPa) showed tensile bond strengths higher than those to caries-affected dentin (13.0 +/- 3.6 MPa and 14.0 +/- 4.3 MPa, respectively). The tensile bond strengths obtained with Scotchbond Multi-Purpose were similar in normal and caries-affected dentin (20.3 +/- 5.5 MPa and 18.5 +/- 4.0 MPa, respectively). The hybrid layers created by All Bond 2 in normal dentin and by Clearfil Liner Bond II in normal or caries-affected dentin showed phosphoric acid and sodium hypochlorite resistance, whereas the hybrid layers created by All Bond 2 in caries-affected dentin and those created by Scotchbond Multi-Purpose to normal and caries-affected dentin showed partial susceptibility to the acid and sodium hypochlorite treatment. The results indicate that the strength of adhesion to dentin depends upon both the adhesive system used and the type of dentin. Moreover, the quality of the hybrid layer may not always contribute significantly to tensile bond strength.

Analysis of Variance↗

PubMed1995

Effect of pulpal pressure on adhesion of resin composite to dentin: bovine serum versus saline.

The purpose of this study was to compare the tensile bond strengths of resin composite to dentin, mediated by two new bonding systems (Scotchbond Multi-Purpose and Clearfil Liner Bond II), under simulated pulpal pressure when diluted bovine serum or saline was used as the pulpal fluid. The bond strengths of the two bonding systems to dentin (under a pulpal pressure of 15 cm of water) obtained when bovine serum was used were statistically significantly higher than those obtained when saline was used. These data suggest that the primers of these bonding systems decreased the dentinal permeability when the bovine serum pulpal fluid was used through the precipitation of serum proteins by the primers in the dentinal tubules. This may have allowed better penetration of the bonding resin monomers into the conditioned dentinal structure, thus improving the bond strength. These findings support the idea that topical application of dentinal bonding systems may be an effective therapy for treating hypersensitive dentin.

Animals↗

PubMed1995

Treatment and prognosis of a vertically fractured maxillary molar with widely separated segments: a case report.

This is a report of the treatment and prognosis of a maxillary second molar exhibiting a complete vertical crown-root fracture. The buccal and palatal segments were widely separated by as much as 2 mm and were immobile. To restore this tooth, it was essential to bring the segments into close apposition. This was accomplished by application of orthodontic elastics to the tooth crown in combination with a wire splint. After approximately 1 month of continuous use of the orthodontic elastics, the dislodged segments were suitably repositioned close to their original positions. The tooth was then endodontically treated and restored with a cast complete crown. The restored tooth has been functioning well, with periodic periodontal maintenance, for more than 3.5 years, indicating a promising prognosis.

Adult↗

PubMed1994

The influence of age and depth of dentin on bonding.

OBJECTIVES: The purpose of this study was to investigate what influence the two variables of dentin depth and age may have on the tensile bond strengths of three bonding systems. METHODS: Dentin discs prepared from human molars were divided into young and old, superficial and deep surfaces. Three bonding systems, Scotchbond Multi-purpose (3M Dental Products), Superbond D-liner (Sun Medical Co.), and Liner Bond II (Kuraray Co.) were the materials tested for tensile bond strength. In addition, the structural variation of the resin-impregnated, or hybrid, layer was compared among the two variables and three bonding systems. RESULTS: Tensile bond strengths exceeding 10 MPa were obtained for all materials. After ANOVA, an effect on tensile bond strength could be attributed to dentin age or depth for only Superbond D-liner used on deep-young dentin as compared with old-superficial dentin. All other group comparisons failed to show any variation between dentin depth or age. However, specimens bonded to deeper dentin showed slightly lower strengths. SEM observations showed thicker resin-impregnated layers for Scotchbond MP and Superbond D-liner compared with Liner Bond II. Liner Bond II exhibited a thinner and more diffuse resin-impregnated layer, believed to be due to the different dentin conditioning method. SIGNIFICANCE: Dentin age or depth may not show as great an influence on bond strengths with the newer type of bonding systems. The resin-impregnated layer quality, rather than thickness, is believed to be the most important factor for obtaining high tensile bond strengths.

Age Factors↗

PubMed1994

Early tensile bond strengths of several enamel and dentin bonding systems.

Tensile bond strength tests are commonly used for the evaluation of adhesive dental materials. The majority of these tests are carried out after 24 h of storage in water. However, determination of the early tensile bond strength could be more important, especially in relation to gap formation between the cavity surface and the restorative material. This study investigated the tensile bond strengths of five enamel/dentin bonding systems and two experimental dentin bonding systems. Tensile bond strengths were obtained at one min, ten min, and 24 h after the resin composite was cured. Bond strengths at the early stages were always somewhat less than the 24-hour test results. For the enamel/dentin bonding systems, a significant difference was found between the enamel and dentin bond strengths at all time periods, except with Superbond D-liner and Liner Bond. The experimental group with glyceryl methacrylate as the primer produced a good 24-hour result (14.3 MPa), but the early bond strengths were no different from those in the non-primer-treated groups. It was concluded that this material may actually retard the polymerization of the bonding resin. Previous workers have suggested that a tensile bond strength in the order of 20 MPa is necessary for gap-free restorations to be obtained. Should this be the case, then all of the materials tested, from the aspect of early bond strength, lack the strength for prevention of gap formation, although Superbond D-liner and Liner Bond approached this hypothetical figure. These systems, Superbond D-liner and Liner Bond, also exhibit small differences between the enamel and dentin tensile bond strengths.

Analysis of Variance↗