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Biomedical subjects

R L Erickson

Publications and source records attributed to R L Erickson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Acoustic correlates of breathy vocal quality.

The purpose of this study was to evaluate the effectiveness of several acoustic measures in predicting breathiness ratings. Recordings were made of eight normal men and seven normal women producing normally phonated, moderately breathy, and very breathy sustained vowels. Twenty listeners rated the degree of breathiness using a direct magnitude estimation procedure. Acoustic measures were made of: (a) signal periodicity, (b) first harmonic amplitude, and (c) spectral tilt. Periodicity measures provided the most accurate predictions of perceived breathiness, accounting for approximately 80% of the variance in breathiness ratings. The relative amplitude of the first harmonic correlated moderately with breathiness ratings, and two measures of spectral tilt correlated weakly with perceived breathiness.

Adult↗
PubMed1994

Evidence for a recent decrease in measles susceptibility among young American adults.

As part of an ongoing evaluation of US Army immunization policies, two serologic surveys were conducted at an army basic training center. Antibody status to measles, mumps, and rubella were determined by an ELISA in 969 soldiers in 1989 and 992 soldiers in 1990. Measles seronegativity rates, directly adjusted to the 15- to 24-year-old US population in 1980, decreased from 21.3% in 1989 to 12.5% in 1990 (P < .001). Decreases also were observed in mumps (16.2% to 14.7%) and rubella seronegativity rates (18.4% to 14.3%) from 1989 to 1990 but were not statistically significant. In subgroup analyses, significant decreases in measles seronegativity were observed in younger, white, male, and female cohorts. There is evidence that susceptibility among young adults had declined, although it remains unclear if this is due to increased immunization or exposure to natural disease.

Adolescent↗
PubMed1994

Root surface treatment with glass ionomers and resin composites.

Recommendations for restorative treatments of root surfaces are made difficult by a lack of information on the etiology of root conditions and on the clinical performance of available materials used to treat these conditions. Resin composite and glass ionomer materials are popular restorative materials because they are esthetic and can bond to tooth structure. However, the role each can play in restoration of root surface lesions is not well documented. This article presents a rationale for using these materials for a number of restorative situations.

Chlorhexidine↗
PubMed1994

Shear bond strength of composite to enamel and dentin using Scotchbond Multi-Purpose.

A laboratory study was conducted to determine the shear bond strength to enamel and dentin using the Scotchbond Multi-Purpose dental adhesive system. High shear bond strengths of P50 composite to both human enamel (26.8 +/- 5.2 MPa) and bovine enamel (24.8 +/- 4.1 MPa) were found when the system was used according to manufacturer's directions. The mean bond strength for human dentin (25.5 +/- 7.5 MPa) was also similar to that found for bovine dentin (23.4 +/- 4.9 MPa). Variations in the recommended application technique were examined on bovine dentin. Extreme air drying of the primer slightly reduced the mean shear bond strength (19.7 +/- 6.4 MPa), while a significant reduction was observed when the adhesive resin was aggressively air-thinned (10.1 +/- 6.6 Mpa).

Acid Etching, Dental↗
PubMed1994

An in vitro study of mechanical heart valve sound loudness.

The purpose of the study was to measure the valve sound loudness of eight 25 mm aortic mechanical heart valve prostheses under controlled laboratory conditions in an isolated acoustic environment. A specially designed single-chamber pulse duplicator was constructed within an anechoic box that isolated the sounds of the valve from external noise. The valves were closed with a stimulated aortic pressure waveform of three different amplitudes. Valve sound loudness was measured with ISO-532/B (Zwicker method), which is based on a model of loudness perception that is better than dB(A), the traditional A-weighted sound pressure level. The average loudness for each valve was St. Jude Medical, 0.97 sones; CarboMedics, 0.98 sones; Sorin Biomedica Bicarbon, 1.08 sones; Edwards Tekna, 1.92 sones; Edwards Duromedics, 2.36 sones; Monostrut, 2.48 sones; Sorin Biomedica Carbocast, 3.17 sones; and Medtronic Hall, 3.57 sones. There was a positive trend between valve sound loudness and aortic drive pressure for most valves in the study.

Aortic Valve↗
PubMed1994

Preventing disease and non-battle injury in deployed units.

Most military physicians know that disease and non-battle injuries (DNBIs) have historically caused more death during war than battle injury. Most DNBIs are preventable, but many unit surgeons and physician assistants, especially at battalion/squadron and brigade/wing level, may not have had the benefit of preventive medicine training or experience. The authors present a logical and thorough framework that all unit surgeons can use to organize their preventive efforts.

Humans↗
PubMed1993

Decreases in invasive Haemophilus influenzae diseases in US Army children, 1984 through 1991.

OBJECTIVE: To document trends in the incidence of invasive Haemophilus influenzae diseases in young children of US Army active duty soldiers following the publication of H influenzae type b immunization recommendations for young children between 1985 and 1990. DESIGN: A population-based surveillance of hospital discharge diagnoses for H influenzae invasive diseases. SETTING: Military and civilian medical treatment facilities around the world. PATIENTS: There was a mean population of nearly 200,000 US Army health care beneficiaries younger than 5 years of age each year of the study. OUTCOME MEASURES: Annual total and age-specific incidences of the six most common H influenzae invasive diseases in this population (meningitis, epiglottitis, septicemia, pneumonia, cellulitis, and septic arthritis). RESULTS: The annual number of cases of H influenzae invasive diseases decreased from a high of 188 in 1986 to 43 in 1991. The incidence in the age group at highest risk for H influenzae disease, those 6 to 11 months of age, decreased from 355 per 100,000 children in 1986 to 116 per 100,000 in 1991 (P < .0001, chi 2 for trend). The incidence for H influenzae meningitis declined from 59 per 100,000 children in 1986 to 6 per 100,000 in 1991 (P < .0001, chi 2 for trend). CONCLUSIONS: The decrease in H influenzae invasive diseases closely follows the dates of H influenzae type b vaccine licensure for use in progressively younger age groups. Some age groups, however, experienced a decline in disease rates even before becoming eligible for vaccination.

Bacterial Capsules↗
PubMed1991

The susceptibility of young adult Americans to vaccine-preventable infections. A national serosurvey of US Army recruits.

OBJECTIVE: Due to recent resurgences of measles, mumps, and rubella among young US adults, we sought to generate antibody prevalence data for national and military immunization policy evaluations. DESIGN: We used a questionnaire and serological survey of Army recruits to assess antibody status to measles, mumps, rubella, and varicella by enzyme-linked immunosorbent assay and to poliovirus types 1, 2, and 3 by microneutralization assay. SETTING: Basic training reception centers at Fort Benning, Ga., and Fort Jackson, SC. PATIENTS: The study included 1547 US Army recruits who were inducted during September and October 1989. OUTCOME MEASURES: Seronegativity by various demographic factors. RESULTS: Seronegativity rates, directly adjusted to the 15- to 24-year-old US population in 1980, were 20.7% for measles, 15.6% for mumps, 17.5% for rubella, and 6.9% for varicella. For measles, mumps, and rubella, susceptibility was less in females, blacks, and college-educated recruits, and varicella susceptibility was greater in females and blacks. Recruitment who were born after 1969 lacked measles, mumps, and rubella antibodies more often than older recruits. The adjusted seronegativity rates for poliovirus types 1, 2, and 3 were 2.3%, 0.6%, and 14.6%, respectively; trends by age, sex, and race-ethnicity were generally unremarkable. CONCLUSIONS: Among young adult Americans, susceptibility to measles, mumps, and rubella is unevenly distributed and may be substantial. Our findings support national objectives to further improve immunization coverage in school-age and adult populations and provide further impetus for legislation requiring college entrants to present evidence of having received at least two doses of measles vaccine, with one on or after entry into elementary school.

Adult↗
PubMed1991

Radiopacity of restorations and detection of secondary caries.

The aim of this study was to compare the accuracy of radiographic diagnosis of secondary carious lesions adjacent to filling materials with different radiopacities. Class II preparations were made in extracted teeth. One group of teeth (n = 49) had caries in the gingival wall, simulating secondary caries. The control teeth (n = 29) had no caries. Three posterior composite materials (P-30 and two experimental composites) with different radiopacities and amalgam were successively inserted into each cavity. After being radiographed, the "restorations" were removed and a new material inserted. The radiographs were interpreted by 11 dentists, and secondary caries was diagnosed according to a five-point confidence rating. The results obtained with the receiver operating characteristics (ROC) method showed that a semi-radiopaque restoration seemed favorable and that the best radiopacity slightly exceeded that of enamel.

Composite Resins↗
PubMed1991

Vertical angulation of the X-ray beam and radiographic diagnosis of secondary caries.

The purpose of this study was to assess to what extent angulation of an X-ray beam could affect the quality of diagnoses of caries adjacent to restorations with different radiopacities. Amalgam and composite class II restorations with and without secondary caries were done in extracted teeth. The teeth were radiographed using four different vertical angulations -0, 5, 10, and 15 degrees. Eight dentists diagnosed caries lesions on these radiographs. The best diagnostic outcome was found for the composite restorations radiographed at 10 degrees vertical angulation. Diagnosis was generally better for lesions marginal to composites compared to amalgams. The quality of secondary caries diagnosis in connection with amalgam was not significantly affected by variations in vertical angulation from 0 up to 15 degrees.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

The influence of admixing microfiller to small-particle composite resin on wear, tensile strength, hardness, and surface roughness.

A series of photo-initiated composite resins, with a Bis-GMA-TEGDMA resin matrix, was investigated in vitro for occlusal wear, surface roughness, diametral tensile strength, and hardness. The materials contained mixtures of ground quartz (macrofiller, 3 microns) and colloidal silica (microfiller, 0.04 micron), with total filler being constant at 68.5% by volume. The study was conducted to determine the influence of an increasing ratio of micro to macrofiller in the mixtures. When the macrofiller was gradually replaced by 3, 5, 7.5, 10, 15, and 20 vol% of microfiller, wear resistance increased substantially, ultimately to a constant level. Any influence on surface roughness or tensile strength and hardness could not be demonstrated.

Composite Resins↗
PubMed1989

Mechanism and clinical implications of bond formation for two dentin bonding agents.

The mechanism of dentin bonding remains a subject of conjecture. However, sparse evidence is available to support current specific mechanisms for the various systems. Comprehension of the fundamental processes in bonding would encourage a greater appreciation for the critical procedures that ensure clinical success. An SEM study was conducted to examine the mechanism of bonding for two similar dentin bonding systems, Scotchbond 2 and Gluma. For these systems, experimental results support the formation of a mechanical bond resulting from resin infiltration and polymerization within the dentinal matrix. Effective bonding is dependent upon comprehension of the regimented procedures.

Acid Etching, Dental↗
PubMed1987

Dentin bonding agents--a perspective on research and clinical use.

The last several years have shown remarkable advances in the development of dentin bonding agents. Today, a majority of dentists routinely use dentin bonding agents in clinical practice. Yet, despite this widespread acceptance, these materials are still in their infancy and require improvements in their performance as well as an understanding of their adhesion mechanisms. Bond strengths to dentin are sufficient to prove useful but are less than needed for totally reliable results. Furthermore, problems related to polymerization shrinkage of composite restorative materials can compromise the bond to dentin resulting in decreased adhesion and marginal seal. Better materials are now being developed, but, in the meantime, limitations of the current materials should be understood and respected in clinical application.

Dental Bonding↗