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Biomedical subjects

R J Chapman

Publications and source records attributed to R J Chapman.

16 recordsLinked to original sources
PubMed1995

Angulation assessment of anterior single tooth root form implants: technical note.

A technique is presented to evaluate the angulation and position of an anterior single tooth root form implant by means of a surgical template, a pilot osteotomy, and an abutment guide. The space available for the restorative materials can be assessed and the angulation modified, if necessary, to improve the esthetic potential. If the angulation is satisfactory and sufficient room is available for the prosthesis, the surgeon can continue with implant placement at the initial site.

Cuspid↗
PubMed1992

Relative production of IL-1 beta and TNF alpha by mononuclear cells after exposure to dental implants.

Interleukin-1 (also known as osteoclast activating factor, OAF) is a cytokine produced primarily by monocytes and macrophages and is thought to mediate many of the immunologic, metabolic, and endocrine alterations seen with microbial infection, tissue injury, inflammatory disease, and bone loss. Stimuli for IL-1 production include microorganisms, endotoxins (LPS), antigen-antibody complexes, clotting components, and other cytokines. The purpose of this study was to determine whether dental implants stimulated peripheral blood mononuclear cells (PBMCs) to produce IL-1 beta (OAF) as well as tumor necrosis factor (TNF alpha). This production may lead to bone loss or failure of an implant. Three duplicates of five different implants were incubated with 2 x 10(6) PBMCs/ml in 20% autologous serum; the esterase positive PBMCs amounted to 14.5%. Measured by radioimmunoassay techniques and compared to controls, all of the implants except one caused significant in vitro generation of IL-1 beta and TNF alpha. The stimulation of IL-1 beta/TNF alpha production by these materials suggests that they are not physiologically inert and that the IL-1 beta (OAF) production may contribute to a less favorable osseoadaptation. OAF has a physiologic (homeostatic) role in maintenance and alteration of osseous structures, but the level at which physiologic becomes pathologic is unknown. Although there were statistical differences between the cellular response to these implants, the clinical significance of the differences remains to be determined.

Cells, Cultured↗
PubMed1991

A comparison of mandibular denture base extension in conventional and implant-retained dentures.

A border outline for mandibular implant-retained dentures is described. The lingual extension of the impression is greatly reduced compared with a conventional mandibular denture. Because of the implant attachment, the shortened border is more comfortable and does not compromise denture retention. Improper implant position is also discussed with respect to denture extension.

Dental Implants↗
PubMed1990

Variations in occlusal forces with a resilient internal implant shock absorber.

The importance of an internal shock absorber for implant prostheses has concerned many, primarily because the efficacy of a shock absorber to reduce stress has not been demonstrated in vivo. This study examined 15 subjects with unilateral distal extension single implant abutments attached to a single natural tooth abutment to assess the effect of a shock-absorbing element within the implant on occlusal force levels. Occlusal forces and bilateral occlusal similarity were examined using specially adapted research software for the T-Scan occlusal analysis system. The results indicate that there is a significant difference (P less than 0.011) between occlusal forces using an internal shock absorber (18 N) and a titanium internal element (30 N).

Adult↗
PubMed1983

Excessive wear of natural tooth structure by opposing composite restorations.

Extreme care must be taken to evaluate the probable effect of using certain restorative materials to oppose existing tooth structure, particularly when dentin is exposed. In addition, frequent recall examination, every one or two months, is necessary to catch any problems in their beginning stages and to solve them before greater damage can be caused. It is also suggested that evaluation of any occlusal habits be made before deciding on a plan to alter vertical dimension and to carefully consider the effects of the materials used in a restoration on the opposing arch.

Aged↗
PubMed1981

The form of the mandibular anterior lingual alveolar process in partially edentulous patients.

One hundred adult patients needing a Class I mandibular removal partial denture were selected to determine the incidence and prevalence of the form of the mandibular anterior lingual alveolar process. The processes ranged between 2 and 22 mm in height and from 37 degrees to 125 degrees angulations in relation to the occlusal plane. Shapes were found to be sloped (45), vertical (38), and undercut (17). The large variety of sizes and shapes of the lingual alveolar process stresses the importance of a precise impression technique to accurately register the anterior lingual alveolar process. Instructions to the dental laboratory for the design of the proper major connector for each specific situation will improve the quality of the removable partial denture service to the patient.

Adolescent↗
PubMed1981

Maximizing support for maxillary defects.

The use of the medical-grade silicone obturator can aid the prosthodontist attempting prosthetic closure of maxillary defects. This type of obturator prosthesis allows the patient to resume near-normal oral function. It aids in the preservation of the oral structures because it uses the support available from the defect to reduce the force per unit area on the remaining "normal" oral structures.

Denture Design↗
PubMed1981

The medication seminar and primary care education.

This paper defines the need to provide postgraduate psychiatric education to primary care physicians, as well as the need to provide psychiatrists with teaching experiences in the primary care setting. Two psychiatrists in rural New England developed and administered, over an eight-month period, a Balint-type seminar on psychotropic medications, designed to emphasize experiential and two-way learning. The process of the seminar reflected the special problems encountered in post-graduate education of physicians in a rural area. The impact on the instructors and participants had implications for the design and development of future educational programs in both psychiatry and primary care.

Education, Medical, Continuing↗
PubMed1981

The cooperative information project: Part 2: some initial clinical, quality assurance, and practice management studies.

Many of the obstacles inherent in the conduct of primary care research have been overcome by an experimental program in northern New England, the Primary Care Cooperative Information Project. This project uses a medical information network in 44 rural medical practices to carry out both clinical and management research. This paper describes the developmental problems encountered and the results of some initial clinical, quality assurance, and practice management studies conducted by the network and presents observations on its future research directions.

Adolescent↗
PubMed1981

The Cooperative Information Project: Part 1: A sentinel practice network for service and research in primary care.

This is the first of two papers describing the Primary Care Cooperative Information Project (COOP Project), a program that integrates the interests of community physicians, medical school faculty, and health policymakers. This integration has been accomplished through the uniting of 44 rural medical practices in Maine, New Hampshire, and Vermont with faculty at Dartmouth Medical School in clinical research, quality assurance, practice management, and continuing medical education activities. This paper describes the structure, goals, and history of the COOP Project, together with the design, cost, and output of its computerized medical information system.

Family Practice↗
PubMed1979

The impact of a required preceptorship on senior medical students.

The impact of a required preceptorship program was measured by comparing the perceptions of senior medical students who would have elected the preceptorship rotation had it not been required (the elective group) and those who participated only to fulfill the requirement (the required group). The main difference between the two groups before the preceptorship was the elective group's career preference for family medicine and the required group's preference for an internal medicine subspecialty. The preceptorship had no impact for either group on inclinations toward other specialties, preferred practice setting, or assessment of practice location determinants. Both groups, however, perceived an increase in knowledge of primary care practice and confidence in relevant clinical skills following the preceptorship. These results are used to support the value of a required preceptorship program.

Attitude↗
PubMed1975

Trans-chest ventricular defibrillation of heavy subjects using trapezoidal current waveforms.

Effectiveness of four truncated exponential waveform defibrillators for transchest ventricular defibrillation was evaluated in 27 human-sized animals. With all waveforms, effectiveness was virtually 100% for small subjects, but decreased as body weight increased. These data confirm the electrical dose concept for ventricular defibrillation and demonstrate that the truncated exponential waveform is effective only when adequate current is delivered through the subject's chest.

Animals↗
PubMedDate not supplied

Occlusal contact variation with changes in head position.

Ten healthy young adults were examined for changes in occlusal contacts related to three head positions: supine, sitting, and head forward. The contacts were analyzed using T-Scan special research software, which measured the time moments of the first five occlusal contacts. Time moment is a descriptive term calculated from a formula that considers both spatial (where contacts are) and temporal (when contact occurs) aspects of tooth contact and provides a quantitative basis for comparing the dynamics of tooth contact. Paired head positions were analyzed for differences using Student's t test, and it appears that in healthy young adults, initial tooth contacts are substantially influenced by posture.

Adult↗