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Biomedical subjects

J W Reinhardt

Publications and source records attributed to J W Reinhardt.

At least 19 recordsLinked to original sources
PubMed2000

Effect of dentin desensitizers and dentin bonding agents on dentin permeability.

PURPOSE: To determine the effect of dentin desensitizing agents (oxalates and glutaraldehyde) and dentin bonding agents, with and without resin-based composite (RBC) on dentin permeability and morphology of the dentin surface. The influence of saliva and toothbrushing on these agents was also evaluated. MATERIALS AND METHODS: Radicular dentin discs +/-1 mm thick were obtained from extracted human teeth. The thickness of the discs was standardized by grinding them with 600 grit silicon carbide powder. Both pulpal and periodontal surfaces of the discs were treated with 6% citric acid for 2 min prior to the baseline measurement of dentin permeability. Permeability was measured for the discs, using a split-chamber apparatus, at four different time points: at baseline, after treatment with each desensitizing modality, after 24 hrs of saliva immersion and after simulated toothbrushing equivalent to 3 weeks of normal brushing. The treatment modalities were: Sensodyne Dentin Desensitizer, Gluma Dentin Desensitizer, All-Bond DS (primers without etching), Etch+Primers (All-Bond 2 system), Etch+Primers+Adhesive and Etch+Primers+Adhesive+RBC (AElite Flo). Radicular dentin discs were prepared separately for scanning electron microscopy (SEM). One group was left untreated as the control group. Discs in the other groups were treated with the modalities listed above. One disc from each group was viewed under the SEM after treatment with the desensitizing modality. The second disc in each group was viewed after 24 hrs of saliva immersion following desensitizing treatment and the third disc after 3 weeks of simulated toothbrushing following desensitizing treatment and saliva immersion. RESULTS: The greatest reduction in permeability was caused by All-Bond DS followed by Sensodyne Dentin Desensitizer and Etch+Primers+Adhesive+RBC. Gluma Dentin Desensitizer, Etch+Primers, and Etch+Primers+Adhesive did not reduce permeability by a significant amount. Saliva immersion increased permeability significantly only for the Gluma and Etch+Primers+Adhesive groups. There was a trend towards increase in permeability after toothbrushing; however, this increase was not statistically significant for any group (P > 0.05). Thus, placement of primers without etching (All-Bond DS) reduced permeability more than any other treatment modality. These data indicate that etching a sensitive dentin area may be appropriate only if RBC is to be placed in the area. Exposure to saliva and toothbrushing countered the decrease in permeability caused by dedicated desensitizers and dentin bonding agents. The SEM micrographs revealed that in most cases, form corroborated function and the morphology of the dentin surface corresponded to the dentin permeability values.

Acid Etching, Dental↗
PubMed1997

Effect of HEMA-containing dentin desensitizers on shear bond strength of a resin cement.

PURPOSE: To determine whether the use of two HEMA-containing dentin desensitizing agents [Health-Dent Desensitizer with fluoride (H) or Gluma Desensitizer (G)], when applied at simulated "cavity preparation" and "cementation" appointments, affects the bond strength of lab processed resin composite restorations cemented to dentin. MATERIALS AND METHODS: The occlusal surfaces of 70 teeth were ground flat to expose dentin and polished to 600 grit. Teeth were randomly assigned to seven groups (n = 10). The treatments were applied in two sessions in order to simulate cavity preparation and cementation appointments. Water (W) was applied as a control instead of a desensitizing agent. H or G were applied for 30 seconds with a rubbing motion (1) at preparation appointment (HW and GW), or (2) at cementation appointment, after etching (WH and WG), or (3) at both sessions (HH and GG). In the control group, water was applied at both sessions (WW). All-Bond 2 and Dual Cement were used according to manufacturers' instructions to cement pre-polymerized resin composite cylinders (4 mm diameter) to the dentin surfaces using a force of 1.0 MPa. Specimens were thermocycled 300x and tested in shear until failure. Data was analyzed using one-way ANOVA and Tukey's HSD test at alpha = 0.05. RESULTS: Mean bond strength and standard deviations are reported in MPa: GW = 7.4 +/- 6.0; WW = 7.7 +/- 5.8; HW = 8.2 +/- 4.3; WH = 10.8 +/- 6.2; GG = 13.5 +/- 6.0; HH = 13.8 +/- 7.1; WG = 19.9 +/- 8.8. There were no significant differences in bond strengths for GW, WW, HW, WH and GG. Shear bond strength for WG and HH was significantly higher than all groups except for GG. Results of this in vitro study indicate that the use of desensitizers at the preparation and/or cementation appointment does not interfere with bond strengths of resin cement to dentin.

Analysis of Variance↗
PubMed1997

Surface treatment effects on amalgam repair strength.

PURPOSE: To determine whether the use of microetching and bonding agents could improve the shear bond strength between aged and freshly added dental amalgam, simulating an amalgam repair. MATERIALS AND METHODS: Aged amalgam surfaces were treated with either a carbide bur or carbide bur + microetcher (Al2O3 abrasive). Five commercially-available adhesive systems were tested. Fresh amalgam was condensed through a split mold onto each prepared amalgam surface. Two control groups were included: a positive control consisting of non-repaired amalgam, and a negative control consisting of aged specimens which received neither carbide bur nor microetching preparation prior to the addition of fresh amalgam. In addition, one group received only carbide bur and another received only carbide bur and microetching treatments, without any adhesive. Following storage and thermocycling, each specimen was tested for shear bond strength. RESULTS: The mean shear bond strength of the repaired samples treated with carbide bur alone (25.8 MPa) was not exceeded by any of the other treatments. Neither microetching nor use of an adhesive agent significantly improved amalgam-to-amalgam shear bond strength. In some cases, use of an adhesive agent significantly decreased the shear bond strength of repaired amalgam samples.

Aluminum Oxide↗
PubMed1997

Surface treatment techniques for resin composite repair.

PURPOSE: To compare bond strengths of fresh resin composites to previously polymerized ("aged") composites following various surface treatments. MATERIALS AND METHODS: Eighty Pertac Hybrid (PH) and an equal number of Silux Plux (SLX) specimens were fabricated and stored for 1 week prior to surface treatment. The specimens were then polished and stored for an additional 24 hours prior to final surface treatment. The surface treatments included use of one of the following: (1) diamond bur (DB), (2) microetcher with 50 microns Al2O3@80 psi pressure (ME), (3) high-pressure air abrasion with 27 microns Al2O3@psi, (KCP), or (4) low-pressure silicate ceramic deposition using 30 microns particles@34 psi (CJ-S) with a microetcher. Half of the samples were treated with a silanating agent. Fresh resin composite (same type as used for the aged specimen) was bonded to the treated surfaces, and specimens were then stored 24 h and thermocycled 300 x at 5 degrees and 55 degrees C prior to testing for shear bond strength. Two-way ANOVA was used to determine significant differences between mean shear bond strengths for both composite materials. RESULTS: Significant differences were found between the groups for both surface treatment and silane use (P < 0.05). The interaction between the two main effects was also significant (P < 0.05). Overall, the highest bond strengths were found when the low-pressure silicate ceramic deposition system (CJ-S) was used, with or without silane.

Air Pressure↗
PubMed1995

Effect of Gluma desensitization on dentin bond strength.

PURPOSE: To determine whether the use of Gluma as a desensitizing agent on tooth preparations has any effect upon the bond strength of a resin composite restoration cemented to dentin. MATERIALS AND METHODS: Forty extracted human molars which were caries and restoration-free were occlusally reduced to remove enamel. Twenty of the teeth received a Gluma desensitization treatment and 20 were untreated (controls). Following a 7-day storage period, simulated resin composite inlays were bonded to all of the dentin specimens, using either All-Bond 2 with All-Bond Crown & Bridge Cement or OptiBond with Porcelite Dual Cure. Twenty-four hours later, the shear bond strength of the specimens was determined. RESULTS: Statistical analysis (paired t-tests) indicated no significant difference in bond strength for Gluma-treated specimens when compared to controls, for either bonding material.

Analysis of Variance↗
PubMed1994

Bond strength and microleakage of current dentin adhesives.

OBJECTIVES: The purpose of this in vitro study was to evaluate shear bond strengths and microleakage of seven current-generation dentin adhesive systems. METHODS: Standard box-type Class V cavity preparations were made at the cemento-enamel junction on the buccal surfaces of eighty extracted human molars. These preparations were restored using a microfill composite following application of either All-Bond 2 (Bisco), Clearfil Liner Bond (Kuraray), Gluma 2000 (Miles), Imperva Bond (Shofu), OptiBond (Kerr), Prisma Universal Bond 3 (Caulk), Scotchbond Multi-Purpose (3M), or Scotchbond Dual-Cure (3M) (control). Lingual dentin of these same teeth was exposed and polished to 600-grit. Adhesives were applied and composite was bonded to the dentin using a gelatin capsule technique. Specimens were thermocycled 500 times. Shear bond strengths were determined using a universal testing machine, and microleakage was evaluated using a standard silver nitrate staining technique. RESULTS: Clearfill Liner Bond and OptiBond, adhesive systems that include low-viscosity, low-modulus intermediate resins, had the highest shear bond strengths (13.3 +/- 2.3 MPa and 12.9 +/- 1.5 MPa, respectively). Along with Prisma Universal Bond 3, they also had the least microleakage at dentin margins of Class V restorations. SIGNIFICANCE: No statistically significant correlation between shear bond strength and microleakage was observed in this study. Adhesive systems that include a low-viscosity intermediate resin produced the high bond strengths and low microleakage. Similarly, two materials with bond strengths in the intermediate range had significantly increased microleakage, and one material with a bond strength in the low end of the spectrum exhibited microleakage that was statistically greater. Thus, despite the lack of statistical correlation, there were observable trends.

Analysis of Variance↗
PubMed1993

A clinical study of nightguard vital bleaching.

This double-blind, randomized, controlled clinical trial was designed to evaluate the efficacy and soft tissue effects of nightguard (mouthguard) vital bleaching. Subjects were assigned to one of two treatment groups, overnight (insertion of mouthguard at bedtime) or 3-hour (replenishment of test solution at hourly intervals for a total of 3 hours exposure daily). The experimental solutions included two products that are specifically designed for tooth bleaching, one product that is marketed as an oral antiseptic, and a control solution (glycerin). Each subject participated for a 3-week period. Tooth color analysis (shade determination) was done at baseline and the end of the treatment. Gingival and Plaque Indices were recorded at baseline and at the end of each week of study. Results indicated that the bleaching treatment was effective in most cases and caused no tissue inflammation or significant tooth sensitivity. The mean Gingival and Plaque Indices were generally lower (denoting improvement) at the end of treatment. Patient satisfaction with the procedure was high.

Analysis of Variance↗
PubMed1992

Side-effects: mercury contribution to body burden from dental amalgam.

The purpose of this paper is to examine and report on studies that relate mercury levels in human tissues to the presence of dental amalgams, giving special attention to autopsy studies. Until recently, there have been few published studies examining the relationship between dental amalgams and tissue mercury levels. Improved and highly sensitive tissue analysis techniques have made it possible to measure elements in the concentration range of parts per billion. The fact that mercury can be absorbed and reach toxic levels in human tissues makes any and all exposure to that element of scientific interest. Dental amalgams have long been believed to be of little significance as contributors to the overall body burden of mercury, because the elemental form of mercury is rapidly consumed in the setting reaction of the restoration. Studies showing measurable elemental mercury vapor release from dental amalgams have raised renewed concern about amalgam safety. Mercury vapor absorption occurs through the lungs, with about 80% of the inhaled vapor being absorbed by the lungs and rapidly entering the bloodstream. Following distribution by blood circulation, mercury can enter and remain in certain tissues for longer periods of time, since the half-life of excretion is prolonged. Two of the primary target organs of concern are the central nervous system and kidneys.

Alzheimer Disease↗
PubMed1990

Composite resin esthetic dentistry survey in New England.

This study collected information on various aspects of esthetic dentistry, including the time used and income produced while delivering treatment to noncarious teeth. A mail survey was sent to 521 randomly selected dentists in the six-state New England area (approximately 7% of the total active dentists in that region); the response rate was 74%. The results indicated that dentists are providing a substantial amount of esthetic treatment on noncarious teeth.

Adult↗
PubMed1989

The need for operative dentistry services: projecting the effects of changing disease patterns.

The declining incidence of caries in children and adolescents has caused speculation that there will soon be a great reduction in need for restorative services among adults. This study used recent dental epidemiological data, population estimates, and numerous alternative assumptions to calculate the hours of adult operative dentistry treatment need in the US in 1972, 1990, and 2030. According to those calculations, the total hours of need were about 125 million in 1972. In 1990 and 2030, the projected hours of need were determined to be about 150 million and 192 million, respectively.

Adolescent↗
PubMed1988

Risk assessment of mercury exposure from dental amalgams.

Much attention is being focused upon the issue of mercury exposure from dental amalgam restorations and the potential for adverse health effects. This controversy has grown beyond the confines of the dental profession itself and is becoming an emotional public health issue. In hope of regaining good health, many dental patients with chronic systemic diseases are considering replacement of their amalgams. Dentists are increasingly being challenged to prove the safety of amalgams. Recently, systematic methods have been established for quantitative evaluation of environmental risks. This study brings together the quantitative methodologies of risk assessment and the knowledge of mercury exposure from dental amalgams to estimate the safety of dental amalgam restorative therapy. Analysis concludes that the margin of safety for mercury toxicity in humans from dental amalgams is approximately 8- to 30-fold. There are many uncertainties involved in this estimate, and further studies are warranted to improve its precision.

Dental Amalgam↗
PubMed1988

The associations of age and dentition status with caries treatment in adult males.

This study explores patterns of treatment for caries in adults. Data were collected as part of the Veterans Administration Dental Longitudinal Study. The 698 subjects received comprehensive dental examinations at three-year intervals for approximately ten years. The subjects were classified into three age groups and three dentition status categories. Total need for treatment was defined as the number of surfaces that initially had caries plus those developing caries over the three subsequent examinations. Analysis of variance was used to determine if there were significant associations between age or dentition status groups and the percent of total need that was treated by extraction, treated by restoration, or remained untreated. Significant associations were noted: (1) between age and the percent of carious surfaces extracted, (2) between dentition status and the percent of carious surfaces restored, and (3) between dentition status and the percent of surfaces extracted. These findings were interpreted to indicate that future cohorts of older patients with greater numbers of teeth are likely to seek operative treatment for diagnosed caries.

Adult↗
PubMed1985

Composite resin compatibility and bond longevity of a dentin bonding agent.

The shear strength of a commercial dentin bonding agent was studied using human dentin in vitro. The agent was tested for compatibility with three proprietary composite resins. In addition, some samples were subjected to prolonged water immersion and thermocycling to determine effects on bond strength. There was no statistically significant difference in shear strengths when the three composite resins were used. In addition, there was no difference in shear strengths among those samples thermocycled or immersed for up to one year. The implications of this study are that the dentin bonding agent may be used with several composite resins with no significant difference in bond strengths, and that the bond seems stable when subjected to immersion or simulated intra-oral thermal stresses.

Adhesives↗
PubMed1984

Build-up and repair of light-cured composites: bond strength.

Interfacial bond strengths of light-activated composites were measured as a function of age using a transverse strength test. Bond strength between layers decreased with the age of the initial layer and reflected the setting curves of the composites. The highly-filled composites exhibited the greatest bond strengths. Uncut surfaces provided a better substrate for bonding than did ground surfaces. Use of a bonding agent on both uncut and ground surfaces improved bond strengths. Mean repair strengths of light-activated composites were similar to those of self-curing composites. Composites with ground surfaces aged for one wk had mean repair strengths 27% of the cohesive strength without bonding agent and 48% with bonding agent.

Chemical Phenomena↗