Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Laboratory Procedures”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed1987

Alternative prosthodontic technique for tissue-integrated prostheses.

This modified technique for fabrication of tissue-integrated prostheses saves valuable clinical time for the dentist and treatment time for the patient. The technique differs in that a modified denture is placed in the mouth the day of the second operation, impression copings are eliminated at the final impression, the framework is fabricated before jaw relation records, a high-content palladium alloy is used for the framework, the master cast is flasked similar to a complete denture technique, and the access openings are closed with a light-cured resin. Prerequisites for a tissue-integrated prosthesis are not violated and comparable results are achieved. The technique can also be used in maxillary arches and, with slight modifications, for partially edentulous patients. This technique has been used 3 years for 35 jaws in 37 patients, with 184 fixtures. Four fixtures have failed, producing a 98% success rate. All prostheses have remained continuously stable. Economy of clinical time and laboratory procedures in the prosthodontic phase increase the acceptance of osseointegration in clinical dentistry. The cooperative efforts of all disciplines will provide a greater acceptance of this treatment modality, which will enhance the patients' quality of life.

Dental Alloys↗
PubMed1988

Margin design for esthetic posterior metal ceramic crowns.

Variations in margin designs for ceramic metal restorations have been used to fulfill the many requirements for such restorations. The trend in our population toward greater esthetic awareness places increased emphasis on esthetics. This trend necessitates a high level of esthetics in posterior restorations. Commonly used posterior margin designs have been described and their inherent weaknesses and strengths have been reviewed. An alternative design has been proposed with its advantages in esthetics, tissue compatibility, cleansibility, and versatility. The clinical and laboratory procedures for this design have been described.

Crowns↗
PubMed1989

A modification of the Thompson dowel rest for distal-extension removable partial dentures.

A prefabricated Thompson dowel rest semiprecision attachment system for distal-extension removable partial dentures deserves consideration in the treatment planning of periodontally involved dentitions. It is a system that provides for rotation and therefore stress-breaking with controlled movement. Many other stress-breaking systems provide for rotation without specific control. In addition, the Thompson dowel rest system is the only stress-breaker that is intracoronal not extracoronal. This prefabricated system offers facilitation of laboratory procedures, eliminates the need for utilization of gold for dowels, reduces the size of the rest seats, and aids in the preservation of the integrity of the hard and soft supporting tissues.

Denture Design↗
PubMed1990

A provisional and new crown to fit into a clasp of an existing removable partial denture.

A technique that forms an abutment crown to fit into an existing clasp of a removable partial denture by relining an acrylic resin pattern is described. The outer contour of the pattern is made within an irreversible hydrocolloid impression by use of Duralay autopolymerizing acrylic resin applied with precision dispensers. The pattern is formed before tooth preparation and is made approximately 0.4 mm thick. After tooth preparation, the shell pattern is relined with the same autopolymerizing resin and the existing removable partial denture is fitted over it. The gross pattern is trimmed and the margins refined on a die made from an elastomer impression. The refined pattern is cast and finished, avoiding reduction of the contours established. A second crown is similarly formed in tooth-colored autopolymerizing acrylic resin. It serves as a provisional restoration that allows the patient to wear the removable partial denture while the laboratory procedures are performed.

Crowns↗
PubMed1992

Bar-retained overdentures for implants--technical aspects.

The principles of the laboratory procedures for making overdentures retained by bar abutments on ITI implant fixtures are described, and details of producing the master casts, making a soldered bar, and processing a prosthesis incorporating a cobalt-chromium alloy strengthener are given.

Chromium Alloys↗
PubMed1992

A soft tissue simulated cast for implant prosthesis.

A master cast that simulates the mucosa around implant fixtures and abutments facilitates implant prosthesis fabrication. It is helpful if this simulation is not altered during laboratory procedures. A technique is described for a master cast that includes a removable mucosal component. This technique can be applied when either implant or abutment analogs are positioned in the cast.

Dental Implants↗
PubMed1992

Accuracy and dimensional stability of a combined hydrocolloid impression system.

The accuracy of a combined hydrocolloid impression system was studied as a function of time of pour. There was little change in dimension between posts for all time intervals studied. No statistically significant differences were noted among the observation periods until 3 hours. The results indicate that for the impression system studied, a 3-hour pouring time can be used for transport to a commercial dental laboratory, provided the impressions are stored in 100% relative humidity. The hydrocolloid impression system tested resulted in a stone cast of slightly deviating dimensions compared with the master model. Therefore laboratory procedures should compensate for cement thickness, taking into account the minimal changes in dimensions of the die.

Alginates↗
PubMed1993

Orbital prosthesis with a magnetically retained ocular component supported by osseointegrated implants.

Positioning of the ocular component within an orbital prosthesis must simulate conversational gaze. Using osseointegrated implants and an associated superstructure, a fixed reference point can be established for positioning an ocular prosthesis. This method can simplify the laboratory procedure and obviate the need for ocular component repositioning in replacement prostheses. This article describes the fabrication of an orbital prosthesis with a magnetically retained ocular section supported by osseointegrated implants.

Alloys↗
PubMed1993

Five techniques for single tooth replacement on endosseous root-form implants.

Internally hexed and threaded root-form implants provide the clinician with many new treatment options for single tooth restorations. Coupled with an interlocking hex on the abutment, they provide stability for single tooth restorations while maintaining the options of screw or cement retention. Five techniques for fabricating single tooth restorations are presented. Clinical and laboratory evaluations of implant angulation, quantity and quality of the gingival tissues, and limitations in vertical height are discussed in relation to design, abutment selection, and laboratory procedures for each restoration. These techniques permit design of each restoration to meet the unique anatomic, functional and esthetic needs. Both screw-retained and cement-retained abutments and prostheses are discussed.

Dental Abutments↗
PubMed1989

A potential mechanism underlying the voluntary suppression of tardive dyskinesia.

Many clinicians have observed that patients with tardive dyskinesia (TD) can voluntarily suppress the movements to some extent. The mechanism by which voluntary control is exerted most likely involves peripheral feedback. Quantitative analyses of isometric and isotonic jaw stability were conducted in patients with and without TD to test the general hypothesis that involuntary movements of TD may be brought under voluntary control via one of two receptor mechanisms; muscle length and/or muscle force. Results indicated that in the absence of length feedback patients with TD exhibited significantly greater instability while patients without TD performed within normal limits. This suggests that patients with TD utilized muscle length feedback to suppress motor instability but were unable to utilize muscle force feedback to suppress instability. Implications for the use of laboratory procedures in the measurement and clinical management of TD are discussed.

Antipsychotic Agents↗
PubMed1986

Autonomic arousal and pain sensitivity in women with premenstrual syndrome at different phases of the menstrual cycle.

Eleven women with a clinical diagnosis of premenstrual syndrome (PMS) and ten non-PMS control women were compared on physiological measures in the intermenstrual and premenstrual phases of their menstrual cycle. Heart rate (HR) and skin conductance level (SCL) were monitored during baseline conditions and in response to a stressful laboratory procedure. Analyses for HR revealed a three-way interaction (groups X phase X tests) which approached significance indicating that the PMS group was generally lower during the intermenstrual testing but was higher in the premenstrual phase. No significant differences were observed on behavioral measures (pain threshold, pain tolerance) between the groups. Pain intensity ratings were found to be overall higher in the PMS group irrespective of menstrual cycle phase. The role of cognitive-perceptual processes is discussed in the context of the acquisition and maintenance of PMS symptomatology.

Adult↗
PubMed1975

Mutagenicity testing with Salmonella typhimurium strains. I. Unusual phenotypes of the tester strains.

Some of the Salmonella typhimurium strains in mutagenesis testing are atypical. Unlike the wild S. typhimurium these do not produce H-2-S, are not agglutinated by S. typhimurium typing sera and on fermentation of carbohydrates they do not produce gas. Thus these tester strains cannot readily be identified as S. typhimurium by standard laboratory procedures. This may cause a problem in the differentiation of tester strains from bacterial contaminants. The possibility exits that these phenotypic traits may affect the response of the strains to mutagens.

Mutagens↗
PubMed1995

Safety evaluation of biological and biotechnology-derived medicines.

Evaluating the 'safety' of drugs produced by biotechnology resembles the assessment of conventional 'new chemical entities,' but with certain major differences. The 'quality' of the product requires careful control because of concern about the carry-over of DNA, immunogenic proteins, endotoxin and process chemicals. Equally the potency and purity of the product must also be considered, as well as its identity. The toxicity testing of rDNA-derived proteins, monoclonal antibodies and vaccines, although increasingly being swept under the umbrella of conventional studies, should be empirically devised according to the nature and physiological effects of the substance, taking account of the responsiveness of suitable species for non-clinical testing, the potential immunogenicity of heterologous proteins and any effect the drug may have on physiological mechanisms and the immune status of the test animals. Conventional types of single and multidose and reproduction toxicity experiments can then be adapted to detect and investigate any hazard of the novel drug. Kinetics, metabolism and drug interactions should be explored and the regulatory demand for genotoxicity data satisfied. If appropriate, immunological actions, including auto-immunity, can be sought. 'Safety-in-use' should then be predictable with some confidence, because of the extent of the toxicological investigations and because activities that cannot be examined will have been delineated, e.g. lack of a responsive species or of a suitable laboratory procedure.

Animals↗
PubMed1996

Clinically relevant EEG studies and psychophysiological findings: possible neural mechanisms for multiple chemical sensitivity.

This paper addresses the evidence for the face, construct, and criterion-related validity of the olfactory-limbic/neural sensitization model for multiple chemical sensitivity (MCS). MCS is a poorly-understood, controversial condition in which low levels of environmental chemicals are reported to trigger disabling levels of illness in certain individuals. Neural sensitization processes could generate an endogenous amplification of responsivity to exogenous substances, thereby providing a plausible explanation for the apparent lack of a classical toxicological dose-response relationship in MCS. Convergent data from both survey and psychophysiological studies of MCS patients and of persons from the community without MCS, but who report elevated frequency of illness from chemical odors (cacosmics), support the involvement of the limbic system and the sensitizability of cacosmics, as predicted by the model. Recent studies show that cacosmics do sensitize their heart rate, blood pressure, and plasma beta-endorphin responses to repeated exposures to a novel laboratory procedure involving dietary manipulations over time. Cacosmia may represent a pathological form of neural plasticity. Taken together, the model and the available evidence suggest the need for more intensive investigation of MCS from the standpoint of possible neurobiological mechanisms affecting cognitive, emotional, and somatic functions.

Animals↗
PubMed1984

Diagnosis and treatment of bacterial meningitis.

In the clinical approach of bacterial meningitis, the following points are stressed. Rapid identification of the germ, pending the results of the cultures. Various laboratory procedures are reviewed such as the Gram stain, the counterimmunoelectrophoresis, lactate determination and limulus assay of the CSF. Because of the local impaired host defences as well as the poor penetration and partial bioinactivation of most of the antibiotics in the CSF, large doses of the drugs are necessary to ensure sufficient levels and bactericidal titers. Specific antimicrobial therapy of meningitis is reviewed, with an emphasis on the third generation cephalosporins which appears to be the key to the treatment of Gram negative infections.

Aminoglycosides↗