Biomedical subjects

M F Burrow

Publications and source records attributed to M F Burrow.

72 records · Page 4Linked to original sources

PubMed1993

Tensile bond strength and curing gap formation of a dentin bonding resin.

Tensile bond strength and contraction gap tests were carried out using a new dentin bonding resin in association with various dentin conditioning and priming materials in vitro. For the tensile bond test, significant differences were found between the nonconditioned and conditioned dentin, and the primed and non-primed dentin surfaces. The strongest bond was obtained using a combination of phosphoric acid conditioning and priming with HEMA in glutaraldehyde at 151.3 kgf/cm2. Gap test results showed the presence of gaps in all of the test groups, but with variation in the extent of gap formation. A not significant, inverse correlation was determined between the tensile bond strength and gap tests (R = -0.65). The new bonding resin obtained good bond strengths in all cases, but high bond strengths can only be obtained with a combination of etching and priming. Similarly, the smallest gaps were associated with the etched and primed groups.

Animals↗

PubMed1993

The long term durability of bond strengths to dentin.

The aim of this study was to investigate the durability, throughout one year, of tensile bond strengths (TBS) to bovine dentin using various commercial and experimental bonding systems. Specimens were stored in a controlled solution of ion-exchanged water containing plaster chips and sodium azide. From the results it was concluded that the changes in TBS were not uniform over time, but a significant decrease was usually observed. For Super Bond D-liner and KB-100, the TBS were the highest and exhibited remarkable stability over the test period. The mode of fracture was noted to vary depending on the treatment system used, and was independent of TBS. Generally, the fracture mode tended to show increases in adhesive/cohesive failures within the resin over time. Super Bond D-liner always exhibited adhesive type failure at the tooth interface, and later involved failure in the hybrid layer. KB-100 showed very little change in failure over one year, being usually adhesive between bonding resin and resin composite. The results from this study indicate the need to carry out durability studies for the basic evaluation of all bonding systems. It was shown that the use of a controlled storage solution is important.

Acid Etching, Dental↗

PubMed1992

Effect of aging and caries on dentin permeability.

Extracted human teeth were collected from young (20-28 yrs) versus old (45-69 yrs) patients. The teeth were divided into carious and noncarious groups. Slabs were created from the mid-coronal occlusal dentin. Carious lesions were excavated and the smear layers on both normal and excavated carious dentin were removed with 37% phosphoric acid (1 min). The permeability (hydraulic conductance) of old normal dentin was only 20% of that obtained in young normal dentin but all of the specimens were permeable. Young carious dentin was only 14% as permeable as young normal dentin and only 1 out of 7 specimens was not permeable. All 7 specimens of old carious dentin were impermeable. Scanning electron microscopy of old and carious dentin exhibited far more intratubular crystals than normal dentin, providing a structural basis for the functional observation.

Adult↗

PubMed1991

Color change in light-cured resins exposed to daylight.

The clinical yellowing of anterior composite resin restorations with time is often the cause for their replacement. This work examined in vitro the effect of sunlight and water separately and together on color changes in the lighter shades of 16 resins. The natural radiation (ultraviolet and visible) was greater than would be expected in clinical use, and the color changes were generally only slight for most resins, as judged by standardized photographic recording and visual inspection of transparencies over time. The changes were greater when sunlight and water were combined. The light-cured surface was less affected than the distal surface. The hydrolysis action by water was particularly marked for one resin, which also showed a high release of camphoroquinone-type catalyst. Marked clinical discoloration may be as much or more affected by absorption of food colorants than by sunlight and water.

Color↗

PubMedDate not supplied

Adhesion of resin-modified glass ionomer cements using resin bonding systems.

OBJECTIVES: To compare the in vitro shear bond strength of two commercially available resin-modified glass ionomer cements (RmGIC) to bovine dentine, with and without the use of adhesive bonding systems. METHODS: Ninety-six flat bovine dentine surfaces were divided into eight groups for bonding procedures. Fuji II LC and Vitremer were bonded to dentine that had been treated with and without Clearfil Photo Bond, Clearfil Liner Bond, or Clearfil Liner Bond II. The control group consisted of specimens that were treated as recommended by the manufacturer of each resin-modified glass ionomer cement. The bonded assemblies were stored in tap water for 24 h at 37 degrees C, and shear bond strengths measured using a universal-testing machine at a crosshead speed of 1 mm/min. RESULTS: For the control group, shear bond strength of Fuji II LC was significantly greater than Vitremer (P < 0.005). However, when any of the resin bonding systems was applied, no statistical difference between Fuji II LC and Vitremer was determined (P > 0.05). The Clearfil PhotoBond and Liner Bond groups showed similar bond strengths (P > 0.05), but were significantly less than Liner Bond II (P < 0.001). CONCLUSIONS: A recent bonding system combined with the RmGICs exhibited the greatest shear bond strength to dentine, irrespective of chemical differences that may exist between the two RmGICs.

Adhesives↗

PubMedDate not supplied

Clinical evaluation of a resin-modified glass ionomer adhesive system--results at three years.

One hundred non-carious cervical lesions were restored with either Silux Plus or Estio LC resin composite using Fuji Bond LC as the bonding agent. Thirteen patients of mean age 60.5 years participated in the study. The retention rate at three years was: Silux Plus, 94%; Estio LC, 100%; total, 97%. Marginal discoloration of aesthetic significance was present around three restorations, two of which were in one patient.

Chi-Square Distribution↗

PubMedDate not supplied

The effect of long-term storage on nanoleakage.

To evaluate the durability of dentin bonding over time, the nanoleakage of four dentin bonding systems (Single Bond, Stae, Clearfil SE Bond and PermaQuik) over 24 hours, three months, six months and 12 months, was investigated. 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 following manufacturers' instructions. The bonded surface was covered with < 1 mm thick layer of Silux Plus resin composite and light cured for 40 seconds. The specimens in each dentin-bonding group were randomly assigned to four sub-groups and kept in phosphate buffered saline solution (pH 7.4) containing 0.01% sodium azide at 37 degrees C for 24 hours, three, six or 12 months. The margins of all specimens were finished and polished with Sof-Lex disks after initial 24-hour storage. At the end of each storage time, the surrounding tooth surfaces except for 1 mm adjacent to the restoration were coated with nail varnish. The samples were immersed in a 50% w/v solution of silver nitrate for 24 hours, placed in photodeveloping solution and exposed to fluorescent light for eight hours. The samples were cut longitudinally and buccoligually, polished, mounted on stubs, carbon coated and observed in a Field Emission-SEM using backscattered electron mode. The results showed that systems using phosphoric acid as the etchant had a line of silver deposition at the base of the hybrid layer. Silver deposition increased in all systems over 12-months storage, with PermaQuik changing the least. Nanoleakage of the dentin bonding systems increased slightly during the 12-month storage period, indicating that they may be subject to hydrolytic attack over time.

Bisphenol A-Glycidyl Methacrylate↗

PubMedDate not supplied

Clinical evaluation of a resin-modified glass ionomer adhesive system: results at five years.

One hundred non-carious, non-undercut cervical lesions were restored with Silux Plus or Estio LC and bonded with Fuji Bond LC. The restorations were evaluated yearly for retention and marginal discoloration. After five years, the overall retention rate was 96%. Of the 41 restorations examined at five years, five had clinically evident marginal discoloration.

Chi-Square Distribution↗

PubMedDate not supplied

Micromorphological study of resin-dentin interface of non-carious cervical lesions.

This study examined the interfaces between two dentin adhesives, namely, One Coat Bond, Clearfil SE Bond and a resin-modified glass ionomer cement (Fuji II LC) and the dentin of non-carious cervical lesions (NCCLs) with FE-SEM, and compared them with the interfaces produced with "normal" dentin. Fifteen human premolars each with a buccal NCCL were used. Cervical cavities were prepared on the lingual surface of the same teeth for the normal (control) dentin. All lesions and prepared cavities were cleaned with a slurry of pumice and water. The teeth were randomly divided among the three products that were applied according to the manufacturers' instructions. For the resin-bonded specimens, the cavities were restored with resin composite. All specimens were stored in 37 degrees C tap water. Resin-bonded specimens were observed using FE-SEM after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite (NaOCl). The resin-modified glass ionomer cement (RM-GIC) specimens were observed after 10% phosphoric acid and 5% NaOCl treatment. The hybrid layer could be observed for the two adhesive systems in all specimens, but the thickness varied depending on the bonding system used and the dentin substrate. The results suggested that the hybrid layer produced in normal dentin was slightly thicker than that of NCCLs. Further, the hybrid layer thickness decreased in all specimens after NaOCl treatment.

Bicuspid↗

PubMedDate not supplied

Pits and fissures: morphology.

The morphology of fissures occlusally was examined by splitting teeth along fissures; this split occurred from the base of the fissure and was checked by serial sectioning. The conclusion is that fissures tend to be an association of adjacent pits. Staining of teeth for fissure shape determination indicates a high presence of organic material in fissures and pits with stained pellicle between pits. The pellicle is often very evident on the lower inclines of cusps, in the region where retention is sought for sealants. In a second phase, an examination of a large number of extracted molars showed that the occlusal fissure extension buccally in lower molars and lingually in upper molars was nearly always interrupted by an enamel col between adjacent cusps. Grooves occlusally or axially adjacent to fissures are often surfaced with stained pellicle. This may be mistaken on visual examination without magnification as extensions of fissures.

Bicuspid↗

PubMedDate not supplied

Pits and fissures: remnant organic debris after acid-etching.

The purpose of this study was to compare the ability of liquid and gel etches to remove remaining debris in occlusal pits and fissures in vitro after cleansing using a conventional technique or air-water slurry method. A suitable stain differentiated between etched enamel, unetched enamel, and pellicle or debris. The results statistically indicate that etching does not remove much of the organic debris, and there was no difference between a liquid or gel etchant. Agitation of the etchant did not aid pellicle removal.

Acid Etching, Dental↗

PubMedDate not supplied

Comparative SEM and TEM observations of nanoleakage within the hybrid layer.

Most adhesive interface studies have involved SEM demonstration of the penetration of adhesive resins into demineralized dentin surfaces with subsequent creation of hybrid layers. Nanoleakage is a term that describes the diffusion of small ions or molecules within the hybrid layer in the absence of gap formation. The present microscopic study examined the nanoleakage of the hybrid layer using a silver nitrate staining technique. Adhesive dentin sandwiches, which were immersed in a silver nitrate solution, were prepared for both SEM and TEM examination using both the Clearfil Liner Bond and All-Bond 2 adhesive systems. Both systems demonstrated silver accumulation within the hybrid layers. Clearfil Liner Bond System showed scattered silver particles at the bottom two-thirds of the hybrid layer by both SEM and TEM observation, whereas All-Bond 2 revealed stained fiber-like structures within the full thickness of the hybrid layer. To evaluate the quality of the hybrid layer, the utilization of tracer molecules such as silver nitrate that are detectable by both SEM and TEM is proposed. It is important to determine the location and morphology of these nanometer-sized porosities that may permit the hydrolysis of collagen fibers and degradation of adhesive monomers.

Collagen↗

PubMedDate not supplied

In vivo adhesive interface between resin and dentin.

V-shaped cervical cavities prepared in monkey teeth were restored with several dentin bonding systems, and the in vivo resin-dentin interfacial structures were observed under the scanning electron microscope using an argon-ion etching technique. The hybrid layer could be clearly observed; its depth was dependent on the conditioner/primer used and tended to be thinner at the deep part of the cavity. Resin tags were also clearly observed, and their structure at the inner part was noted to be rougher than that closer to the tubule orifices. When 37% phosphoric acid gel was used, the tags in the deeper parts of the cavity were much rougher. Hemispherical and spherical roughened structures were observed directly above the tubule orifices, which were thought to be a mixture of dentinal fluid and bonding resin that had flowed out from the tubules. The acidic primer containing maleic acid and HEMA could not remove the smear plugs, and undissolved smear particles were observed in the tubules.

Acid Etching, Dental↗

PubMedDate not supplied

Opacity and color changes of tooth-colored restorative materials.

Internal opacity and color changes of several esthetic direct restorative materials were determined using an accelerated test proposed by Asmussen (1981). Five chemically cured composites, seven light-cured composites, and three resin-modified glass-ionomer cements were placed in acrylic rings. After curing, they were left at 37 degrees C for 1 week before baseline measurement, and then stored in 60 degrees C distilled water up to 4 weeks. Color change was determined by a color analyzer, and contrast ratio representing opacity was calculated. All chemically cured composites tested discolored to dark yellow or dark brown after 4 weeks. Opacity decreased for two macrofilled composites. Light-cured composites discolored slightly, but their opacity change was negligible. All resin-modified glass-ionomer cements tested showed an abrupt decrease of opacity at the initial stage, with accompanying darkening of the materials. Opacity decrease was found to be a factor of discoloration for some tooth-colored restorative materials, and might be caused by a refractive index change of the matrix phase of the materials.

Analysis of Variance↗

PubMedDate not supplied

Early bonding of resin cements to dentin--effect of bonding environment.

The aim of this study was to evaluate early tensile bond strengths of three commercial resin cements (a dual-cured and two chemically cured) to bovine dentin. Bonding was performed in two environmental conditions, namely room environment (23 degrees C/50% RH) and oral environment (30 degrees C/80% RH). Tensile bond strengths were recorded at 10 minutes, 1 hour, and 1 day after the bonding procedure was completed and were analyzed using one-way ANOVA, Fisher's PLSD test, and Student's t-test. The results showed that bond strengths were statistically greater for all materials (P < 0.05) over time, except for Bistite Resin Cement between 10 minutes and 1 hour (P > 0.05). Variation between the bonding environments was observed only for Bistite Resin Cement at both 10 minutes and 1 hour, and Panavia 21 at 10 minutes. It was concluded that bond strengths were initially weak for the chemically cured materials, and all materials showed significantly greater bond strengths over the first 24 hours, but bonding environment had little influence.

Analysis of Variance↗

PubMedDate not supplied

Bond strengths of resin to enamel and dentin treated with low-pressure air abrasion.

The effect of low-pressure (41.8 psi) air abrasion with alumina and glass beads on bonding to tooth substrates was evaluated. Tensile bond strengths of a bonding resin to air-abraded bovine enamel and dentin were measured. Scanning electron microscopy was used to observe (1) air-abraded surfaces, (2) fractured surfaces after the tensile bond test, and (3) interfaces of bonded specimens. Air abrasion with glass beads significantly decreased the bond strengths to enamel and dentin, whereas air abrasion with alumina decreased adhesion to enamel but not to dentin. The air-abraded enamel and dentin surfaces were irregularly roughened, and smear layers were created by air abrasion. Hybrid layers were observed at the interface between the bonding resin and the air-abraded dentin. The SEM photographs suggested that air abrasion may weaken the tooth surfaces, which could account for the decrease of the bond strengths.

Air Pressure↗

PubMedDate not supplied

Bonding of amalgam and a gallium alloy to bovine dentin.

The shear bond strengths of an amalgam (Permite C) and a gallium alloy (Galloy) to dentin, mediated by four dentin adhesives (Super-Bond D-Liner, Super-Bond D-Liner II, Paama 2, and Panavia 21), were investigated. Flat labial dentin surfaces were prepared from bovine lower incisor teeth. A 3 mm-in-diameter area of dentin was bonded according to each manufacturer's directions before placement of Permite C or Galloy. The bonds were stressed in shear at a crosshead speed of 1 mm/min. The mean shear bond strengths were analyzed using one-way ANOVA and Student's t-test, and fracture modes were assessed under X20 magnification and analyzed using Kruskal-Wallis and Mann-Whitney U tests. Scanning electron micrographs were taken of the bond interface of separate samples. The results showed no significant difference among the bond strengths of Super-Bond D-Liner (2.79 MPa, 2.69 MPa), Super-Bond D-Liner II (3.41 MPa, 2.65 MPa), and Paama 2 (0.70 MPa, 0.50 MPa) bonded to Permite C and Galloy (respective values in parentheses); however, Panavia gave a significantly better bond with Permite C (0.42 MPa) than with Galloy (0 MPa). Super-Bond D-Liner and Super-Bond D-Liner II gave stronger bonds than Paama 2 and Panavia with both Permite C and Galloy. For each dentin adhesive, there was no difference in fracture mode between Permite C and Galloy. It was concluded that, since all bond strengths were very low, none of the dentin adhesives tested would enhance the clinical retention of Permite C or Galloy. However, although the use of Paama 2 with Galloy was originally recommended by the manufacturer for dentin sealing purposes, no adhesion was claimed.

Animals↗

PubMedDate not supplied

Clinical evaluation of a resin-modified glass-ionomer adhesive system.

One hundred cervical caries-free, nonundercut lesions were restored in 13 patients of mean age 60.5 years, using Silux Plus or Estio LC resin composite bonded with Fuji Bond LC. Patients were recalled at 6 months and 1 year. A 1-year cumulative retention rate of 98% was recorded, while marginal staining was absent.

Adult↗