Biomedical subjects
W T Harris
Publications and source records attributed to W T Harris.
The microscopic appearance and effect of toothbrushing on extrinsically stained metal-ceramic restorations.
To clarify the nature and longevity of the extrinsic stain layer of metal-ceramic restorations, a series of experiments were undertaken. It was found, with microscopic examination, that there is little or no diffusion of the stain into the underlying porcelain and that at a thickness of 22 microns the extrinsic stain layer is grossly evident to an observer. Using a fluoride dentifrice caused no significant loss of either stain or surface integrity with 120,000 brush strokes (equivalent to 8.5 years). At 160,000 strokes (equivalent to 11.4 years) there was evidence of loss of surface integrity.
A study of bubbles in a rubber elastomer manipulated under clinical conditions.
One hundred addition reaction silicone impressions were made by students and faculty members using two types of syringes with two syringe tip sizes. A count of the bubbles in the impressions revealed a total of 439 with only one impression completely free of bubbles in either the posterior or anterior test regions. Faculty members, presumably more experienced, confirmed the last out-fewer bubbles hypothesis developed in a previous laboratory investigation, but some students did not. A pneumatically activated syringe produced no fewer bubbles than did the conventional hand-powered syringe but most of the students and faculty members thought it was advantageous. Half believed that more practice with it would be beneficial. We recommend that practicing dentists try to minimize bubbles by extruding the first part of the syringe contents onto the mixing pad or in a distant intraoral location before injecting around the critical tooth preparations.
Provisional restorations for anterior teeth requiring endodontic therapy.
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An abdomino-aortic aneurysm demonstrated on bone scintigraphy as a photon-deficient region.
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A procedure for repairing fractured post-core restorations.
Two methods have been described for dealing with fractured or underextended posts in endodontically treated teeth. They seem to be adequate in preserving teeth that might otherwise have been lost.
Centric relation records for complete dentures.
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Conditioning dentures for problem patients.
We have had considerable success with difficult patients through the use of conditioning dentures. Patients with severe gagging problems have been able to gradually accustom themselves to the presence of dentures in the privacy of their homes and at their own rate of progression. Patients without previous denture experience are given a chance to adjust to problems of speech, salivation, and taste prior to receiving their new dentures. We believe that conditioning dentures should be a part of the treatment sequence for all patients being prepared for their first dentures. Many problems are faced by the new denture patient, and anything the dentist can do to prepare him for this difficult time can increase the chances for success.
The orthopedic relator for fabricating immediate dentures.
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