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Biomedical subjects

R T Williamson

Publications and source records attributed to R T Williamson.

16 recordsLinked to original sources
PubMed1995

Using the existing prosthesis as a provisional restoration.

The remaking of a fixed prosthesis provides a unique opportunity of converting the existing prosthesis to a provisional restoration for use while a replacement is being made. This article describes a technique for using existing prostheses that offers several advantages: less potential wear, increased provisional strength and retention, decreased clinical time and esthetically acceptable contours.

Dental Caries↗
PubMed1995

Clinical application of a soft denture liner: a case report.

Patients with thin, nonresilient mucosa, poor ridge morphology, chronic xerostomia, and acquired or congenital defects are candidates for soft denture liners. Soft denture liners may be placed during fabrication of the new denture or during relining of the existing dentures. Soft mandibular denture liners are ideal for senior patients with resorbed mandibular ridges who need replacement of existing dentures to correct excessively closed vertical dimension of occlusion and for patients who have maxillary complete dentures and mandibular natural teeth, severe loss of maxillary ridge, and clenching habits. Soft denture liners should be used only when needed because of their short service life. However, for those patients who cannot tolerate hard denture bases, soft liners are an appropriate alternative treatment.

Alveolar Bone Loss↗
PubMed1994

Retentive bar overdenture fabrication with preformed castable components: a case report.

Overdenture bar attachment therapy is a rarely chosen treatment option in today's aggressive environment of implant treatment. However, overdenture therapy preserves the sensation of proprioception, preserves the edentulous ridge, maintains the border seal, and provides the patient with good speaking ability and chewing efficiency. The use of preformed components for impression posts, plastic burnout post patterns, plastic burnout bar patterns, attachable screw attachments, and nylon retention clips, which are quickly replaced clinically and induce minimal wear on the bar, have made the fabrication of the overdenture bar attachment easier, quicker, and more precise. This article details the fabrication of a canine splint bar for a bar and clip-retained mandibular overdenture that opposes a complete maxillary denture.

Dental Abutments↗
PubMed1994

Techniques for aesthetic enhancement of porcelain laminate veneer restorations: a case report.

The article is a clinical report of various techniques to enhance the aesthetic outcome of porcelain veneer restorations. Color and contour evaluation, increase in shade value, bleaching, and the use of temporary veneer restorations are presented and discussed. A case is used to illustrate the procedures. The learning objective of this article is to expand and update the knowledge of variations in current porcelain veneer restoration techniques.

Adult↗
PubMed1993

Removing a cemented fixed prosthesis using a crown remover.

It may be necessary to remove a fixed prosthesis for various reasons. This article describes a simple, quick, and inexpensive solution to a difficult problem. The technique has the advantage of saving the patient both money and time.

Dental Debonding↗
PubMed1993

The effect of fatigue on the shear bond strength of resin bonded to porcelain.

PURPOSE: The objective of this study was to determine whether fatigue cycling affects the shear bond strength of a resin that is initially strongly bonded to porcelain. MATERIALS AND METHODS: Thirty-five disks of a feldspathic/leucite porcelain were fired on a phosphate-bonded investment material. Each disk was etched with hydrofluoric acid and treated with a silane solution and an adhesive. Resin cement composite cylinders were applied to the treated porcelain and light cured. All specimens were stored for 1 week in distilled water at 37 degrees C and then thermocycled for 1000 cycles in water between 2 degrees C and 50 degrees C. Fifteen of the specimens were randomly selected as control specimens. The remaining were subjected to fatigue cycling. A shear load was applied parallel to the bonded surface and cycled in a square wave between 0 and 26 N at 2 Hz for 27,500 cycles. All specimens were fractured in shear at 1.27 mm/min, and the shear bond strength was determined. RESULTS: Fifteen percent of fatigued specimens and 6.7% of the control specimens showed at least partial adhesive failure. All other specimens in both groups failed cohesively in the porcelain. There was no significant difference in the mean bond strengths of the fatigued and control groups (analysis of covariance, P > .05). CONCLUSIONS: For the conditions investigated, cyclic fatigue did not reduce the bond strength of this resin/porcelain system.

Analysis of Variance↗
PubMed1993

Methods for aesthetic evaluation in replacement of ceramic fixed prosthetics.

After numerous years in situ, ceramic fixed prostheses appear high in value when compared with the adjacent natural teeth, and the patient may desire the replacement of the prosthesis primarily for aesthetic reasons. This article provides exact information on preoperative shade evaluation, modification of a manufactured shade tab, custom shade fabrication, and soft tissue cast fabrication to help to ensure optimal results. The learning objective of this article is an enhanced understanding of the principles of aesthetic restorations.

Color↗
PubMedDate not supplied

Orthodontic correction of maxillary flaring using provisional restorations.

An unconventional orthodontic correction can be accomplished by using preexisting provisional restorations, which can be modified for use in active tooth movement or splinted together for orthodontic anchorage. This technique has an advantage over conventional fixed appliance orthodontic therapy because it can accomplish tooth movement concurrently with restorative and periodontal therapy. Consequently, the timing or sequencing of periodontal and restorative treatment is optimal, and the overall treatment is more efficient. The learning objective of this article is to describe the minor tooth movement necessary to achieve the optimum occlusal scheme, crown form, and tooth position for the forces of occlusion to be displaced down the long axis of the periodontally compromised teeth. Once the occlusion, periodontal health, and crown contours for the provisional splinted restoration are acceptable, the final splinted restoration can be similarly fabricated, and it becomes an excellent orthodontic retainer.

Acrylic Resins↗
PubMedDate not supplied

Effects of grinding, polishing, and overglazing on the flexure strength of a high-leucite feldspathic porcelain.

The objective of this study was to determine how surface treatments and moisture affect the flexure strength of a high-leucite feldspathic porcelain. Uniaxial flexure strength was measured for porcelain beams whose surfaces were coarse ground, overglazed, or polished. Half of the specimens were stored in distilled water and tested while their surfaces were coated with distilled water. The other half were stored in a dry environment and tested immediately in dry air. The high-leucite feldspathic porcelain was found to be sensitive to roughness and surface stresses, similar to leucite-free and low-leucite feldspathic porcelains. The experimental method used, however, was not sensitive enough to detect susceptibility to moisture.

Aluminum Silicates↗