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Biomedical subjects

Christopher D Lynch

Publications and source records attributed to Christopher D Lynch.

28 records · Page 2Linked to original sources
PubMed2003

Case report: management of the flabby ridge: re-visiting the principles of complete denture construction.

Displaceable tissue on edentulous ridges may present a considerable clinical challenge to dental practitioners when providing complete dentures. Surgical excision techniques or use of dental implants has provided clinicians with methods of addressing this particular difficulty. However careful consideration and application of the principles of complete denture construction can provide a less invasive and less complex form of treatment. This article describes one such clinical scenario, and demonstrates the use of a suitable impression technique that is based on successful manipulation of the thermoplastic nature of the impression material.

Alveolar Process↗
PubMed2003

Quality of materials supplied to dental laboratories for the fabrication of cobalt chromium removable partial dentures in Ireland.

The adequacy of prescription for fabrication of cobalt chromium removable partial dentures is often regarded as being less than ideal. This study examines the nature and quality of written instructions and master impression sent to dental laboratories in Ireland for fabrication of cobalt chromium removable partial denture frameworks. Questionnaires were issued to dental laboratories seeking specific information relating to the materials (impression materials and trays) and written instructions supplied, as well as the technicians' opinion regarding the suitability of these materials. One hundred completed questionnaires were returned. One-third of master impressions were made using a plastic stock tray and alginate; technicians felt that one-fifth of master impressions were unsuitable; almost three-fifths of written instructions were inadequate. The quality of clinical information examined was found to be less than adequate.

Alginates↗
PubMed2002

Prosthodontic management of the curve of Spee: use of the Broadrick flag.

Proper management of the occlusal plane is an essential consideration when multiple long-span posterior restorations are designed. When restorations are added to an existing tooth arrangement characterized by rotated, tipped, or extruded teeth, excursive interferences may be incorporated, resulting in detrimental sequelae. The curve of Spee, which exists in the ideal natural dentition, allows harmony to exist between the anterior tooth and condylar guidance. An instrument called the Broadrick flag has been used to assist in the reproduction of tooth morphology that is commensurate with the curve of Spee when posterior restorations are designed; its use prevents the introduction of protrusive interferences. Consideration also must be given to lateral excursive movements when the occlusal plane is designed. In this article, the importance of the curve of Spee in prosthodontic and restorative dentistry is discussed, and a patient treatment demonstrating use of the Broadrick flag is described.

Adult↗
PubMed2002

Surface microhardness of a resin composite exposed to pulse-delayed plasma arc lamp irradiation, in vitro.

Groups of samples of a light-activated resin composite were exposed, using a 3-step pulse-delayed protocol, to a plasma arc unit. Further groups were exposed with the light-curing guide positioned at increasing distances from the composite surface. The pulse-delayed protocol yielded a progressive increase in microhardness number at the end of each step but with a maximum mean value significantly less than the controls. Increasing the irradiation distance yielded a progressive and significant decrease in microhardness number.

Analysis of Variance↗
PubMedDate not supplied

Overcoming the unstable mandibular complete denture: the neutral zone impression technique.

UNLABELLED: This article describes a technique for improving the stability of mandibular complete dentures for patients who have a diminished mandibular neutral zone. The technique involves making an impression which is shaped by the patient's oral musculature, and which defines the shape and contour of the patient's neutral zone. A case report is presented in which the use of this technique is described. It is hoped that this article will increase the awareness of dental practitioners to the use of this technique. CLINICAL RELEVANCE: The neutral zone impression technique is a useful technique when providing mandibular complete dentures. Its use can overcome some of the denture stability difficulties caused in some patients by a more powerful oral musculature, or in patients who have poor or altered neuromuscular control.

Dental Impression Technique↗
PubMedDate not supplied

A survey of chrome-cobalt RPD design in Ireland.

PURPOSE: The aims of this study were to investigate the quality of written instructions given to dental laboratories for fabrication of chrome-cobalt removable partial dentures (RPD) in Ireland, and to examine the extent and nature of technical/laboratory support available for the fabrication of this prosthesis type. MATERIALS AND METHODS: All dental laboratories listed in the commercial telephone book were contacted and invited to participate in the study. Written instructions received by dental technicians for fabrication of chrome-cobalt RPDs were examined for evidence of four design variables: denture base configuration, retention, support, and connector design. The use of diagrams was also examined. RESULTS: Of 112 dental laboratories listed, 100 agreed to take part. Sixteen laboratories had the facilities to fabricate chrome-cobalt frameworks on their premises; 122 sets of written instructions were received. All four design variables were described in 10% (n = 12) of instructions, 7% (n = 9) contained reference to three variables, 13% (n = 16) contained reference to two variables, and 17% (n = 20) contained reference to one variable. No design features were prescribed in 53% (n = 65), and 5% (n = 6) requested the technician to design the prosthesis. Only 7% (n = 8) of instructions included a diagram. CONCLUSION: A high proportion of written instructions to dental laboratories regarding fabrication of chrome-cobalt RPDs contained no reference to the mentioned design variables.

Chromium Alloys↗
PubMedDate not supplied

In vitro study of surface microhardness of a resin composite exposed to a quartz-halogen lamp.

OBJECTIVES: To determine the minimum exposure times consistent with optimized surface microhardness numbers (VHN) for the top and bottom surfaces, respectively, of a resin composite (1.5-mm depth) cured using a quartz-halogen activation lamp. Additionally, to determine the conditions appropriate to achieve optimized bottom/top hardness ratios. METHOD AND MATERIALS: Disk specimens of a commercial resin composite restorative (Spectrum TPH) were exposed to a quartz-halogen lamp, and VHNs were measured for the top and bottom surfaces at elapsed times of 1 hour and 24 hours. RESULTS: Data were dependent on exposure time, time elapsed after exposure, and the surface involved. Exposure time featured limiting values in excess of which no significant increase in microhardness took place. All microhardness data increased significantly over an elapsed time interval between 1 hour and 24 hours postexposure. Microhardness ratios (bottom/top) were dependent on exposure time only and were not influenced by time elapsed after exposure. CONCLUSION: Minimum exposure time may be considered as the greater of the times to achieve optimized top hardness and optimized hardness ratio, respectively.

Composite Resins↗