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Biomedical subjects

J Nassif

Publications and source records attributed to J Nassif.

12 recordsLinked to original sources
PubMed1993

In vivo kinematics of the cervical spine. Part I: Development of a roentgen stereophotogrammetric technique using metallic markers and assessment of its accuracy.

A technique for simultaneous roentgen stereophotogrammetry (RS) was developed, and its accuracy was assessed. In vitro models fabricated from dried cadaveric C4 and C5 vertebrae were used to simulate the motion behavior of the cervical spine. Metallic markers made of Vitallium beads (diameter < 0.3 mm) were implanted into the posterior and anterior surfaces of each vertebra at surgically accessible locations to simulate the bead placement for both posterior and anterior surgical approaches to the cervical spine. A series of roentgen stereo pairs were obtained to systematically assess the accuracy (validity) of displacement measurements in anteroposterior (AP) translation, axial rotation, and flexion/extension. In addition, the effects of soft tissue density on the accuracy of the system were investigated by obtaining a series of roentgen stereo pairs with the experimental model immersed in a water bath. The coordinates of the metallic markers on the radiographs were then digitized by two raters who were not informed of the actual motion (i.e., blind study). The results indicated a high accuracy throughout the study. Overall root mean square errors were 0.07 mm for AP translation, 0.08 degrees for axial rotation, and 0.14 degrees for flexion/extension. The corresponding accuracy estimates (R2 values by linear regression analysis) were very high (0.992, 0.998, and 0.995) when the measurement results were compared with the actual displacements. The water bath did not affect measurement accuracy, indicating that soft tissue density should have little effect on the accuracy of the technique for in vivo applications. This system appears to be an accurate and reliable method for assessment of simulated in vivo cervical spine motion, regardless of the rater. The technique has been further used in in vivo assessment of cervical spine kinematics in one patient to confirm the efficacy of the developed technique.

Atlanto-Axial Joint↗
PubMed1991

Problems associated with interferences in the analysis of serum for polychlorinated biphenyls.

During a recent survey to determine serum concentrations of polychlorinated biphenyls (PCBs) among people living around New Bedford, MA, U.S.A., an unidentified contaminant precluded the quantification of some early eluting Webb and McCall peaks. Loss of data is estimated to have reduced reported serum levels by 12%. Efforts to identify the contaminant by gas chromatography with an electron-capture detector, a Hall electrolytic condutivity detector, and mass spectrometer were not successful. Researchers ascertained, however, that the contaminant is not a PCB, it does not contain halogens, but it may contain phthalates. Vacutainer tubes and closures for serum storage bottles are suspected sources of contamination.

Chromatography, Gas↗
PubMed1984

Duplicating maxillary complete dentures.

A technique for duplication of a maxillary complete denture has been presented. This technique requires no special equipment and can be easily completed in the dental office.

Copying Processes↗
PubMed1984

General considerations prior to relining of complete dentures.

eneral considerations necessary to determine whether a complete denture reline should be attempted or a new denture constructed have been presented. Specific evaluation procedures, including the examination and diagnosis of the patient and the complete denture(s) along with a checklist of complicating factors, have been discussed. Hickey and Zarb have said: "The complicated [nature] of the conditions to be corrected makes [reline] procedures not the simple operations many patients and dentists think they are." The authors emphatically agree.

Denture Rebasing↗
PubMed1984

Current concepts for relining complete dentures: a survey.

Reline procedures for complete dentures have received scant attention in the literature. Fifty-seven dental colleges responded to an 11-item survey on reline procedures. According to the tabulated data, most dental schools recommended the following (not necessarily our recommendations). Leave the denture(s) out of the mouth for at least 24 hours prior to fabrication of the reline impressions. Use tissue-conditioning material only on selected patients. Use Coe Comfort as the tissue-conditioning material of choice. Place either none or one relief hole in the maxillary denture, and place no relief holes in the mandibular denture prior to the impression(s). Place relief holes along the palatal midline of the maxillary denture. No specific size is recommended for the palatal relief holes. Place 1 mm of basal surface relief and 1 to 2 mm of border relief before the reline impression is made. Use a polysulfide rubber base material as the material of choice for reline impressions. Use a closed mouth impression technique. Remove the palate from the maxillary denture prior to processing. Use heat-cured resin (Lucitone) for processing. Use pressure-indicator paste prior to delivery of the denture(s). Remount the complete denture(s) on an articulator after processing for making occlusal corrections.

Denture Rebasing↗
PubMed1978

A self-administered questionnaire--an aid in managing complete denture patients.

A written self-administered questionnaire aids in treating edentulous patients and greatly reduces the possibility of patient dissatisfaction and medicolegal complications. Twenty-two questions have been presented which are to be answered in writing by the edentulous patient prior to the interview and examination. Such a questionnaire has several advantages31: (1) It saves time for the dentist and reduces the cost of treatment. (2) It quickly identifies problem areas. (3) It provides background information on the patient which is useful during the oral interview. (4) It identifies patients who write more intelligently and openly than they speak. (5) It evaluates neuromuscular coordination through handwriting review. (6) It serves as a reference for postinsertion problems. (7) It has legal merit when properly dated and signed and indicates that maximum diagnostic and therapeutic efforts are intended.

Adaptation, Psychological↗
PubMed1976

Examination forms for edentulous patients--a survey.

Examination and diagnosis forms for edentulous patients from 46 dental colleges in the United States were used in this study. Selected data were taken from each form and compiled under four general and 15 specific entries. Some college forms use entries requiring few and succinct responses,while other forms use entries requiring many and detailed responses. It appears that a correlation does exist between the thoroughness of the examination form and the proficiency of the dental student rendering complete denture therapy. Stated in a positive manner, this survey of college complete denture examination forms suggests that most dental students: use a separate complete denture form for the examination and diagnosis; ask for the chief complaint of the patient; ask one to four questions on past dental history; record 10 to 19 entries relating to oral anatomy; record one to four entries relating to oral physiology; record the mental attitude using two to four descriptive terms; and record one prognosis. Stated in a negative manner, this survey of college complete denture examination forms suggest that most dental students: do not examine the present complete dentures worn by the patient; do not use oral diagrams to show unfavorable or abnormal areas; do not ask for a prognosis in two or more areas; do not ask if the patient wears complete dentures at night; do not ascertain the attitude of the patient after receiving complete dentures; do not ask questions on complete denture expectations; do not use an interview form; and do not work with a staff dentist who has a psychology degree. The intent of this study is to create a spectrum of awareness concerning the presence or absence of specific information on the examination forms. Complete denture examination forms would be more beneficial to the dental student if they provided a high quality of pertinent clinical information. This information would aid the dental student in making an intelligent diagnosis, treatment plan, and prognosis.

Humans↗
PubMed1975

Dialogue--a treatment modality.

The findings and philosophy as to why a purposeful interview conducted in the dental office is desirable for the problem patient have been presented. Rapport and meaningful dialogue between dentists and patients are the first steps necessary for successful treatment. Conducting the interview with problem patients in the dental operatory may lead to one-way communication, from the dentist to the patient. The finest clinical oral health procedures may be doomed to failure when patients see themselves more as spectators than as participants in their planned over-all health care.

Attitude↗
PubMed1975

Instructions for patients--a positive factor in removable partial denture service.

Studies have shown that improper wearing and care of removable partial dentures may adversely affect abutment teeth and associated periodontal tissues. A comprehensive removable partial denture service should include not only accurate construction of the prosthesis, but also printed instructions for the patient. Printed instructions help to inform the patient that delivery of removably partial dentures is only a part of our health service designed to maintain good oral health. A text of such concise printed information and instructions for the patient is presented.

Denture, Partial, Removable↗
PubMedDate not supplied

Hydrogel implant for scleral buckling. Long-term observations.

The authors report long-term follow-up clinical observations of 82 eyes in which episcleral or intrascleral hydrogel implants were used as buckles in the repair of rhegmatogenous retinal detachment. Three fourths of the eyes were observed for 24 months or more. The implant material provided a durable and effective scleral buckle, did not produce erosion or infection, and was tolerated well by all patients.

Adolescent↗