Biomedical subjects

G E Schumacher

Publications and source records attributed to G E Schumacher.

At least 19 recordsLinked to original sources

PubMed2006

Effect of a calcium prerinse on salivary fluoride after a 228-ppm fluoride rinse.

The objective of this study was to determine if a concentrated calcium prerinse given before a fluoride rinse would cause an increase in the post rinse sali vary fluoride (F). A panel of 5 subjects used a 30, 150 or 300 mmol/l calcium lactate prerinse followed by a 1-min NaF rinse. All calcium prerinses significantly increased the 1-hour saliva F relative to the NaF control without a prerinse. The maximum increase was produced by the 150 mmol/l calcium lactate prerinse and was about ninefold higher than the NaF control.

Calcium Compounds↗

PubMed2006

Salivary fluoride from fluoride dentifrices or rinses after use of a calcium pre-rinse or calcium dentifrice.

The low concentration of available calcium (Ca) in oral fluids limits the formation of Ca-mediated fluoride deposits that maintain oral fluoride (F) after a topical F treatment. The purpose of this study was to examine if a high concentration of Ca would increase salivary F when used before a F rinse or dentifrice. We found that a Ca pre-rinse (150 mmol/l Ca lactate) or Ca dentifrice (0.084 g Ca glycerolphosphate per gram dentifrice) used immediately before a 60 s 228-ppm F rinse (12 mmol/l NaF) produced a 4.6x or 3.6x increase (p < 0.05) respectively in the 1 h salivary F concentrations over the F rinse alone. Reducing the post-Ca F rinse to 10 s still produced a significant 2.2x increase in salivary F compared to the 60 s F rinse alone. Used with a conventional 1,100 ppm F (i.e. 1,100 microg F per gram) NaF dentifrice (Crest), the above Ca pre-rinse increased 1 h salivary F levels by 2.3x over the F dentifrice alone. However, a F rinse given before a Ca rinse produced no increase in 1 h salivary F concentrations. Although the persistence of these increases requires further study, these results suggest that a moderately high concentration of Ca given shortly before a F rinse or F dentifrice may increase the cariostatic effect of the F product.

Biological Availability↗

PubMed2003

Continuous-fiber preform reinforcement of dental resin composite restorations.

OBJECTIVES: Direct-filling resin composites are used in relatively small restorations and are not recommended for large restorations with severe occlusal-stresses. The aim of this study was to reinforce composites with fiber preforms, and to investigate the effects of layer thickness and configurations on composite properties. It was hypothesized that fiber preforms would significantly increase the composite's flexural strength, work-of-fracture (toughness) and elastic modulus. METHODS: Glass fibers were silanized, impregnated with a resin, cured, and cut to form inserts for tooth cavity restorations. Also fabricated were three groups of specimens of 2mm x 2mm x 25 mm: a fiber preform rod in the center of a hybrid composite; a thin fiber layer on the tensile side of the specimens; and a thin fiber layer sandwiched in between layers of a hybrid composite. These specimens were tested in three-point flexure to measure strength, work-of-fracture and modulus. Optical and scanning electron microscopy were used to examine the restorations and the fiber distributions. RESULTS: Microscopic examinations of insert-filled tooth cavities showed that the fibers were relatively uniform in distribution within the preform, and the inserts were well bonded with the surrounding hybrid composite. Specimens consisting of a fiber preform rod in the center of a hybrid composite had a flexural strength (mean (SD); n=6) of 313 (19)MPa, significantly higher than 120 (16)MPa of the hybrid composite without fibers (Tukey's at family confidence of 0.95). The work-of-fracture was increased by nearly seven times, and the modulus was doubled, due to fiber preform reinforcement. Similar improvements were obtained for the other two groups of specimens. SIGNIFICANCE: Substantial improvements in flexural strength, toughness and stiffness were achieved for dental resin composites reinforced with fiber preforms. The method of embedding a fiber preform insert imparts superior reinforcement to restorations and should improve the performance of direct-filling resin composites in large restorations with high occlusal-loads.

Composite Resins↗

PubMed2001

Therapeutic drug monitoring: do the improved outcomes justify the costs?

In the 30 years that therapeutic drug monitoring (TDM) has moved from an abstract consideration to a routine intervention, issues remain over justifying the benefits in the light of the ever-increasing competition for budgetary resources. Resolving the issues is constrained by various methodological concerns. These include considerations such as: (i) the changed environment of knowledge and practice during the generation in which TDM has been used and evaluated; (ii) the predominance of studies using system-related rather than patient-centred outcomes; (iii) using a timeframe for analysis that is too short; (iv) a lack of rigour in many of the pharmacoeconomic analyses; and (v) excessive use of a site-specific rather than a societal perspective. Current observation suggests that the greatest benefit of TDM accrues from targeted or specialty populations: those with severely decompensated renal function, those at the extremes of age, and those using immunosuppressive, some antineoplastic, some psychotherapeutic and some anticonvulsant drugs. In these situations, safe and humane practice considers TDM a necessity without respect to cost. But for many routine situations with drugs for which TDM has commonly been used in the past, present reliance on the intervention may have become excessive in the light of today's knowledge base of practitioners.

Costs and Cost Analysis↗

PubMed2001

[The studies on microtensile bond strength measurements of two dentin adhesives].

OBJECTIVE: The purpose of this study was to investigate the feasibility of a modified microtensile method used to test bond strengths of two current one-bottle dentin bond systems (Prime & Bond NT, PBNT; Prime one Mirage, P-One) with a parallel match design. METHODS: 15 extracted, caries-free human molars were cut to expose occlusal dentin. A 5 mm deep slot was prepared in each crown to divide the crown into nearly equal halves for accepting treatment of the two dentin bond systems, respectively. After 24 h storage in distilled water at 37 degrees C, the bonded teeth were subjected to two treatments: 5 teeth were tested without further treatment and 10 teeth were thermocycled (2400 cycles, between 5 degrees C and 55 degrees C) prior to bond strength testing. Hour-glass shaped specimens with a distance of approximately 1.0 mm at the narrowest portion were cut from each tooth and tested in tensile mode. RESULTS: Bond strengths (mean MPa) were: for PBNT: 42 & 31, and for P-One 64 & 38 without and with thermocycling, respectively. Two-way ANOVA revealed a significant difference in bond strengths(P < 0.001) between the two systems and when thermocycled. However, a pairwise multiple comparison (Tukey test) showed that after thermocycling the difference between the two systems was not significant (P > 0.05). Regression analysis showed that a correlation existed between the two systems' tensile bond strength values grouped by tooth (correlation coefficient r = 0.575, P < 0.05). CONCLUSION: The modified microtensile method with a parallel match design is feasible and suitable for evaluating two different bonding systems or dentin treatments.

Dental Bonding↗

PubMed2000

Whisker-reinforced dental core buildup composites: effect of filler level on mechanical properties.

The strength and toughness of dental core buildup composites in large stress-bearing restorations need to be improved to reduce the incidence of fracture due to stresses from chewing and clenching. The aims of the present study were to develop novel core buildup composites reinforced with ceramic whiskers, to examine the effect of filler level, and to investigate the reinforcement mechanisms. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whisker surface for improved retention in the matrix. Filler level was varied from 0 to 70%. Flexural strength, compressive strength, and fracture toughness of the composites were measured. A nano-indentation system was used to measure elastic modulus and hardness. Scanning electron microscopy (SEM) was used to examine the fracture surfaces of specimens. Whisker filler level had significant effects on composite properties. The flexural strength in MPa (mean +/- SD; n = 6) increased from (95+/-15) for the unfilled resin to (193+/- 8) for the composite with 50% filler level, then slightly decreased to (176+/-12) at 70% filler level. The compressive strength increased from (149+/-33) for the unfilled resin to (282+/-48) at 10% filler level, and remained equivalent from 10 to 70% filler level. Both the modulus and hardness increased monotonically with filler level. In conclusion, silica particle-fused ceramic single-crystalline whiskers significantly reinforced dental core buildup composites. The reinforcement mechanisms appeared to be crack deflection and bridging by the whiskers. Whisker filler level had significant effects on the flexural strength, compressive strength, elastic modulus, and hardness of composites.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2000

Physicochemical evaluation of bioactive polymeric composites based on hybrid amorphous calcium phosphates.

Amorphous calcium phosphate (ACP)-filled methacrylate composites were recently found to effectively remineralize in vitro caries-like enamel lesions. Their inferior mechanical properties compared to glass-filled composites, however, limit their use as a dental restorative material. In this study, the feasibility of introducing glass-forming elements (tetraethoxysilane or zirconyl chloride) during the low-temperature synthesis of ACP was investigated. Composites based on such hybrid fillers (mass fraction, 40%) were evaluated to establish whether hybridization strengthened the composites via improved interfacial interactions with the polymer phase without compromising the release of the mineral ions. Two types of visible-light cured resins were prepared: BTHZ resin from 2, 2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy)phenyl]propane (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and zirconyl methacrylate (ZrM), and TP resin from TEGDMA and pyromellitic glycerol dimethacrylate (PMGDM). Hybridized fillers and BTHZ- and TP-based composites were characterized by the IR spectroscopy, X-ray diffraction, dissolution/transformation kinetic studies, and biaxial flexure strength (BFS) testing before and after immersion in buffered saline solutions. The feasibility of improving the BFS via hybridization, while retaining, if not enhancing the remineralizing potential was demonstrated for BTHZ-based composites. Both BFS and remineralizing ability of the TP-composites, however, deteriorated upon their exposure to an aqueous environment. Therefore, hybridized ACP-filled BTHZ composites have a potential for utilization in more demanding restorative, sealant, and adhesive applications.

Calcium Phosphates↗

PubMed2000

Indentation modulus and hardness of whisker-reinforced heat-cured dental resin composites.

OBJECTIVES: Recent studies showed that ceramic whisker reinforcement imparted a two-fold increase in the strength of dental composites. The aim of this study was to investigate the indentation response and measure the elastic modulus, hardness, and brittleness of whisker-reinforced heat-cured resin composites as a function of filler level, heat-cure temperature, and heat-cure duration. METHODS: Silica particles were fused onto silicon nitride whiskers to facilitate silanization and to roughen the whiskers for improved retention in matrix. Whisker filler mass fractions of 0, 20, 40, 60, 70, 74 and 79% were tested. Heat-cure temperature ranged from 100 to 180 degrees C, and duration from 10 min to 24 h. A nano-indentation system enabled the measurement of elastic modulus. Fracture toughness was measured and composite brittleness index was calculated. An inlay/onlay composite and a prosthetic composite were tested as controls. RESULTS: Whisker filler level and heat-cure duration had significant effects on composite properties, while heat-cure temperature had non-significant effects. The whisker composite with 79% filler level had a modulus in GPa (mean (SD); n = 6) of 26.9 (1.0), significantly higher than 15.1 (0.2) of an inlay/onlay control, and 16.1 (0.3) of a prosthetic control (Tukey's multiple comparison test; family confidence coefficient = 0.95). The fracture toughness in MPa.m1/2 was 2.22 (0.26) for the whisker composite, higher than 0.95 (0.11) for inlay/onlay control, and (1.13 +/- 0.19) for prosthetic control. The brittleness index was (0.49 +/- 0.07) for whisker composite, lower than (1.02 +/- 0.12) for inlay/onlay control and (0.63 +/- 0.13) for prosthetic control. SIGNIFICANCE: Whisker filler level had a profound influence, heat-cure duration had significant effects, while temperature did not have significant effects, on the properties of whisker composite. The whisker composite had significantly higher elastic modulus and fracture toughness, and lower brittleness than the inlay/onlay and prosthetic controls.

Analysis of Variance↗

PubMed2000

Dental resin composites containing ceramic whiskers and precured glass ionomer particles.

OBJECTIVES: Glass ionomer, resin-modified glass ionomer, and compomer materials are susceptible to brittle fracture and are inadequate for use in large stress-bearing posterior restorations. The aim of this study was to use ceramic single crystal whiskers to reinforce composites formulated with precured glass ionomer, and to examine the effects of whisker-to-precured glass ionomer mass ratio on mechanical properties, fluoride release, and polishability of the composites. METHODS: Silica particles were fused onto silicon nitride whiskers to facilitate silanization and to improve whisker retention in the matrix. Hardened glass ionomer was ground into a fine powder, mixed with whiskers, and used as fillers for a dental resin. Four control materials were also tested: a glass ionomer, a resin-modified glass ionomer, a compomer, and a hybrid composite. A three-point flexural test was used to measure flexural strength, modulus, and work-of-fracture. A fluoride ion-selective electrode was used to measure fluoride release. Composite surfaces polished simulating clinical procedures were examined by SEM and profilometry. RESULTS: At whisker/(whisker + precured glass ionomer) mass fractions of 1.0 and 0.91, the whisker composite had a flexural strength in MPa (mean (SD); n = 6) of (196 (10)) and (150 (16)), respectively, compared to (15 (7)) for glass ionomer, (39 (8)) for resin-modified glass ionomer, (89 (18)) for compomer, and (120 (16)) for hybrid composite. The whisker composite had a cumulative fluoride release of nearly 20% of that of the glass ionomer after 90 days. The whisker composites had surface roughness comparable to the hybrid resin composite. SIGNIFICANCE: Composites filled with precured glass ionomer particles and whiskers exhibit moderate fluoride release with improved mechanical properties; the whisker-to-glass ionomer ratio is a key microstructural parameter that controls fluoride release and mechanical properties.

Acrylic Resins↗

PubMed2000

American translation, modification, and validation of the St. George's Respiratory Questionnaire.

BACKGROUND: The St. George's Respiratory Questionnaire (SGRQ) is a 50-item health status survey specific for chronic obstructive pulmonary disease (COPD) and other respiratory diseases that is available in British English but not American English. The SGRQ's symptom-reporting component requires a 1-year reporting period, which may be too long for reliable and accurate patient recall. OBJECTIVES: The objectives of the present study were to translate the SGRQ from British to American English, modify the reporting period of the symptom-reporting component from 1 year to 1 month, and assess the reliability, validity, and sensitivity to change of this translated modified version in a sample of patients with COPD. METHODS: Based on input from American patients with COPD and health professionals, the SGRQ was translated into American English (SGRQ-A) and then translated back to British English. For SGRQ-A reliability and validity studies, patients were asked to report symptoms experienced over 1 year (reporting period in the original SGRQ) and 1 month (modification made to SGRQ-A). We evaluated 102 patients with COPD (50% female; mean age, 68 years; mean forced expiratory volume in 1 second [FEV1], 1.01 L) at an administrative session before and after completion of a pulmonary rehabilitation program. The SGRQ-A, Chronic Respiratory Disease Questionnaire (CRQ), 36-Item Short Form Health Survey (SF-36), 6-minute walk (6MW), Medical Research Council (MRC) Dyspnea scale, and pulmonary function tests (FEV1 and % predicted FEV1) were used in the assessment battery. RESULTS: The SGRQ-A showed good agreement with the original SGRQ when translated back to British English. Internal reliability (Cronbach alpha) was > 0.70 for all SGRQ-A components except the 1-year symptom-reporting component. Test-retest intraclass correlations were 0.795 to 0.900. Construct validity was strengthened when all SGRQ-A components (except 1-year symptoms and most 1-month symptoms) correlated (P < or = 0.01) with the MRC Dyspnea scale, 6MW, all SF-36 concept scores, and 80% of CRQ domains (r = 0.30-0.72). Discriminate validity was demonstrated when all components of the SGRQ-A with the modified 1-month symptom-reporting period were shown to discriminate better between disease-severity groups (based on patient self-reports of disease severity) than did pulmonary function tests and the 6MW. Responsiveness of the SGRQ-A to change in health status was demonstrated when scores on the Symptoms-1 month and Total-1 month components detected significant improvements in patients' health status (P = 0.02 and P = 0.04, respectively). CONCLUSION: The SGRQ-A with a modified 1-month symptom-reporting period demonstrated reliability and validity in this sample of patients with COPD. Key words: chronic obstructive pulmonary disease, St. George's Respiratory Questionnaire, American translation, reliability, validity, symptom recall.

Adult↗

PubMed2000

Effect in vitro acidification on plaque fluid composition with and without a NaF or a controlled-release fluoride rinse.

Plaque fluid ion concentration changes, especially fluoride, in response to the pH decrease associated with a cariogenic episode are important components of the caries process. A "controlled-release" (CR) fluoride rinse, based on the controlled release of fluoride in the presence of calcium, has been shown to form large fluoride reservoirs in resting plaque. In this study, the in vitro acid-induced release of fluoride, and other ions, was examined in 48-hour-fasted plaque fluid from subjects (n = 11) who received no rinse, or who used a 228-ppm CR or NaF fluoride rinse 1 hr before being sampled. After collection, the plaque was centrifuged to yield plaque fluid, acidified (0.1 microL of 0.5 mol/L HCl per milligram plaque), and then re-centrifuged before a second sample was obtained. Although previous studies indicated a higher plaque fluid fluoride after the new rinse relative to NaF, no statistically significant difference was observed here. Average fluoride release after acidification (average pH, 5.2) was statistically greater following the use of the CR rinse (153 micromol/L) compared with the NaF rinse (17 micromol/L). No fluoride release was seen in the no-rinse samples. The pH, free calcium, phosphate, acetate, propionate, and buffer capacity were not affected by the different amounts of fluoride deposited in the plaque. However, following acid addition, an increase in free calcium and phosphate was observed, which was also independent of the rinse. The large release of fluoride following acidification suggests that the new rinse may provide an improved cariostatic effect.

Acetates↗

PubMed1999

Three-body wear of a hand-consolidated silver alternative to amalgam.

Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

Compressive Strength↗

PubMed1998

Economic and outcome issues for therapeutic drug monitoring in medicine.

Outcome and economic studies pertaining to the use of therapeutic drug monitoring (TDM) are summarized. The studies were classified by a 2 x 2 matrix comprised of process, outcome, system-related variables, and patient-centered variables. Two hundred forty-seven studies conducted from 1974 to 1994, culled from eight summary sources, were reviewed. Almost 75% of the studies reported system-related, not patient-centered, measures for assessing the value of TDM; nearly the same percentage evaluated processes as opposed to outcome measures. Studies comparing TDM to non-TDM populations generally showed that TDM as an intervention reduced the rate of undesirable system-related variables by 50% and increased the rate of desirable system-related variables by 100%. For patient-centered variables, TDM was less dramatic, decreasing the rate of undesirable variables by 15% to 50%. Only 8% of the studies examined economic variables. TDM-influenced changes in process variables resulted in a projected mean annual savings of $37,000. The few studies available of cost-benefit analysis focused on aminoglycosides and showed that TDM yielded a range from 4:1 to 52:1 in benefit-to-cost ratio. Most studies have limitations that include small sample size, short study periods to predict long-term outcomes, no long-term follow-up, and designs for noncontrolled study.

Drug Monitoring↗

PubMed1998

Total testing process applied to therapeutic drug monitoring: impact on patients' outcomes and economics.

The Total Testing Process (TTP) refers to the sequence of 11 steps of laboratory testing, beginning with a clinical question prompted by the patient-clinician encounter and concluding with the impact of the test result on patient care. TTP when applied to therapeutic drug monitoring (TDM) emphasizes that TDM must be considered a process involving a series of steps and interrelated activities and not viewed simply as a numerical value for a serum drug concentration. TTP is also an ideal format for organizing and identifying the system-related and patient-centered variables used in outcomes assessment of TDM, as well as providing a template for collecting the cost data needed for economic analyses. Examples are provided for improving application of TDM by practitioners, clinical laboratories, and educators.

Blood Chemical Analysis↗

PubMed1997

Photoactivated dentin bonding with N-phenyliminodiacetic acid.

OBJECTIVES: The overall objective of this study was to correlate adhesive resin and polymerization initiator chemistry with bonding to dentin that had been treated with N-phenyliminodiacetic acid (PIDAA), a self-etching primer with initiator and co-initiator potential. The hypotheses to be tested were that: (1) the nature of the adhesive resin and (2) the type of polymerization initiator system are critical factors that can influence the bonding of composite restoratives to dentin. METHODS: Three types of bonding resins: (A) a non-carboxylic acid bonding resin (BisGMA/HEMA); (B) a carboxylic acid monomer (PMDM, the control); and (C) a combination system (BisGMA/HEMA/PMDM), along with two types of initiator systems: (1) a self-curing chemical initiator system based on PIDAA and (2) a dual-cure system involving camphorquinone, PIDAA, and visible light irradiation, were tested with a randomized 3 x 2 full factorial design. Solutions of each resin in acetone were tested with and without camphorquinone. Solution (A) was a 50% solution of 1:1 BisGMA/HEMA; Solution (B), a 10% solution of PMDM; and Solution (C), a 50% solution of 2:2:1 BisGMA/HEMA/PMDM in the ratio of 2:2:1. All percents were on a mass basis. (The photoactivated solutions of A, B, and C also contained 0.5% camphorquinone based on the mass of the resin.) Ninety composite-to-dentin specimens were prepared by a 2-step protocol: 1) 60 s application of 20 microL of 0.3 mol/L PIDAA in 1:1 v/v acetone/H2O; 2) 60 s application of 20 microL of one of the six resin solutions, followed by 60 s visible light irradiation. A visible light-activated composite (Silux, 3M) was then applied to each treated surface and irradiated for 60 s. Specimens were stored in distilled H2O (22 degrees C, 24 h) before shear bond testing. The summary statistics were calculated and a two-way ANOVA and Duncan's Multiple Range test were used to discern if the two factors significantly affected the mean shear bond strength. RESULTS: Mean shear bond strengths and standard deviations were obtained (with and without camphorquinone, respectively): (A), 11.0 MPa +/- 3.9 and 4.1 MPa +/- 4.9; (B), 27.0 MPa +/- 5.3 and 13.7 MPa +/- 5.6; (C), 18.3 MPa +/- 5.3 and 7.0 MPa +/- 5.2. The use of camphorquinone significantly enhanced the mean shear bond strengths obtained with the carboxylic, non-carboxylic and combination monomer based adhesive systems (p < 0.0001). For PIDAA-treated dentin, moderate shear bond strengths were obtained with a non-carboxylic acid resin solution containing camphorquinone. The addition of both PMDM and camphorquinone to this resin further improved the shear bond strengths. The highest mean shear bond strength was obtained with the combination of PMDM and camphorquinone (p < 0.05). SIGNIFICANCE: These results suggest that formulations based on PIDAA, PMDM and camphorquinone are more effective as bonding systems than those formulations without PMDM and camphorquinone. PIDAA, a self-etching primer with initiator and co-initiator abilities, appears to interact positively with both carboxylic acid monomers such as PMDM and the photooxidant camphorquinone.

Acetone↗

PubMed1997

N-phenyliminodiacetic acid as an etchant/primer for dentin bonding.

Effective composite-to-dentin bonding has been achieved by the sequential use of dilute aqueous nitric acid (HNO3) and acetone solutions of N-phenylglycine and a carboxylic acid monomer, e.g., p-PMDM. Both the HNO3 pre-treatment and the surface-initiated polymerization that results from reaction of infused N-phenylglycine and PMDM have been identified as key elements of this bonding system. In this study, N-phenyliminodiacetic acid, a unique imino acid derivative with acidic and chelating potential, was evaluated as a dual etchant/primer for dentin bonding. A randomized, 2(3) factorial design was used to study the effects of 3 factors on tensile bond strength (TBS): conditioner (HNO3 vs. no HNO3), primer (N-phenylglycine vs. N-phenyliminodiacetic acid), and primer solvent (acetone vs. acetone:H2O). The three-step protocol consisting of HNO3, N-phenylglycine in acetone, and PMDM in acetone served as the control. The hypothesis tested was that N-phenyliminodiacetic acid could act as both an effective conditioner (i.e., etchant) and as a primer. Two-step protocols that included only N-phenyliminodiacetic acid and PMDM were compared with the control. TBS (n = 10 per group) were determined after 24-hour storage in H2O and analyzed by ANOVA and Duncan's Multiple Range test. Primer solvent was critical for obtaining significant bonding to dentin when HNO3 was omitted. N-phenyliminodiacetic acid in acetone without prior HNO3 etching gave the lowest ranking mean TBS (95% CI, 3.8 +/- 1.9 MPa). In contrast, the mean TBS obtained from samples treated with N-phenyliminodiacetic acid in acetone:H2O without prior HNO3 etching was not statistically different (p > 0.05) from the mean TBS for the control (95% CI, 9.3 +/- 1.8 and 9.8 +/- 1.9 MPa, respectively). Due to its dual function as etchant and primer, N-phenyliminodiacetic acid in acetone:H2O provides for a simplified bonding technique that yields strong, PMDM-mediated adhesion to dentin.

Acid Etching, Dental↗

PubMed1995

A teaching strategy to incorporate patient-centered outcomes assessment in health professional curricula: the class-generated patient profile.

As chronic diseases claim a growing proportion of our population's morbidity, health practitioners are increasingly concerned with the impact of diseases on the physical limitations, psychological status, social role, and overall quality of life of patients. While health professionals have traditionally supplemented their clinical assessment skills with physiologic measures such as temperature, white cell counts, pulmonary function tests, and enzyme levels, as well as functional measures such as range of motion and mobility, they are less facile with measures that describe the limitations in physical, psychological, and social functioning of patients. These latter factors may have a greater overall influence on patient status than physiologic and function indices alone.

Allied Health Occupations↗

PubMed1994

Mild theophylline-related adverse reactions and serum theophylline concentration.

The relationship between theophylline-associated adverse drug reactions (ADRs) and serum theophylline concentration (STC) was studied. Patients with obstructive airway disease who received theophylline on the pulmonary ward of a large urban hospital over a 10-month period were included in the study. Each patient was interviewed within two hours after collection of a sample for determining STC and, without knowing the STC, the interviewer classified each patient into one of the following categories: ADR, no ADR, or indeterminant (symptoms similar to a theophylline-associated ADR but possibly caused by concomitant drugs or comorbidities). ADRs were also classified as to their severity. The interviewer identified 340 ADRs during 201 interviews of 126 patients. All but four of the ADRs were mild. In half of the interviews, patients reported at least two concurrent ADRs. Not including the indeterminant group, ADRs occurred in 69% of the patients, a much higher frequency than previously reported. The mean +/- S.D. STCs for the ADR and no-ADR groups were 6.5 +/- 1.7 and 7.7 +/- 2.0 micrograms/mL, respectively. When the indeterminant ADRs were added to the theophylline-associated ADRs, the resulting group had a mean +/- S.D. STC of 11.5 +/- 3.3 micrograms/mL. No significant association was found between STC and occurrence of ADRs. Theophylline-associated ADRs occurred more frequently than expected at STCs within and below the usually accepted therapeutic range.

Adverse Drug Reaction Reporting Systems↗