David N. Firtell

Posterior peripheral seal distortion related to processing temperature

A conventional acrylic resin was processed at temperatures varying from 135 degrees F to 180 degrees F. No significant distortion in the posterior peripheral seal of a denture base was noted when the material was processed at or below the manufacturers recommended temperature. Statistically significant distortion was noted in the posterior peripheral seal of a denture base when processing was done above the recommended temperature. An acrylic resin specially designed to be boiled produced significantly less distortion in a denture base than the conventional acrylic resin.

Removable partial dentures with rotational paths of insertion: problem analysis.

Removable partial dentures designed to use a rotational path of insertion are technique sensitive. When indicated and when the principles discussed are followed, a denture that uses a rotational path can be highly successful. Tooth coverage can be decreased, which is an advantage in plaque control, caries reduction, and periodontal support. Esthetics can be improved without resorting to intracoronal retainers, and the number of components subject to distortion is reduced. When properly designed and constructed, use of a rotational path of insertion can result in a removable partial denture that is strong, hygienic, and esthetic.

Effect of clasp design upon retention of removable partial dentures.

Abstract A model was constructed to represent an ideal removable partial denture situation with a standardized undercut. Nine chrome-cobalt alloy test frameworks, each representing a different clasp design, were fabricated according to the manufacturers directions. The amount of force required to dislodge each framework from the model was recorded. The frameworks showed the following decreasing order of resistance to vertical displacement from an 0.02″ undercut: (1) “U” infrabulge clasp, (2) ring clasp, (3) Akers clasp, (4) Akers clasp with a wrought gold wire retentive arm, (5) “I” infrabulge clasp, (6) “I” infrabulge clasp with a wrought gold wire retentive arm, (7) Ney No. 2 clasp, (8) “T” infrabulge clasp, and (9) back action clasp.

Maxillofacial prostheses: reproducible fabrication.

Abstract Because no material presently available for external maxillofacial prostheses is completely durable, periodic replacement is a major problem. A method is described that permits consistent refabrication of any prosthesis originally fabricated of silicone with a minimum of time and effort and without the patient being present. This method includes the mixing of earth pigments and silicone to produce standard stock colors from which base shades and surface tints can be compounded by formula. Records of these formulas and preservation of the mold in which the prosthesis was fabricated make it possible to duplicate the prosthesis whenever necessary. This method involves extrinsic tinting, and the advantages and disadvantages of this technique are discussed.

The effect of clinical remount procedures on the comfort and success of complete dentures

Fifteen patients were treated with complete dentures in a routine manner that included a clinical remount. A second group of 15 was treated in the identical manner except that the clinical remount was not performed. The occlusal patterns of all dentures were recorded in the patients mouths at delivery and again 1 week later by using a photoelastic membrane to provide a permanent record. The presence or absence of soreness was also noted for each patient during the week after delivery. Results indicate that clinical remounts significantly reduced the incidence of soreness, preserved the occlusal force, and reduced the changes in occlusal patterns of the dentures. Although both cusped and flat teeth were used in both treatment groups, no significant differences were noted in relation to either form on the basis of the indices studied.

Complete denture prosthodontics for the radiation patient

The increased use of radiation therapy for the control of oral cancer necessitates that all dentists concerned with the rehabilitation of oral cancer patients be familiar with this treatment modality. Radiologic equipment, the rationale for their use, and the sequelae to oral treatment are discussed. Misconceptions have developed concerning the advisability of prescribing complete dentures following radiation therapy. However, clinical experience in the Maxillofacial Unit at the University of California, San Francisco, indicates that most radiation patients can wear complete dentures. The need to follow sound prosthodontic techniques is advocated, along with a few modifications related specifically to the radiation patient. Patient cooperation and meticulous care during and following the placement of dentures are stressed to minimize the risk of tissue necrosis and to preserve the well-being of the patient.

Mandibular complete denture impressions with fluid wax or polysulfide rubber: A comparative study

Some authors have stated that wax cannot be used to make impressions for complete dentures, while others have found that wax has some advantages over elastomeric impression materials. The purpose of this study was to compare mandibular impressions made with a fluid wax to those made with light-body polysulfide rubber. Fifteen maxillary and mandibular complete dentures were made using fluid wax as a final impression material. For comparison, 15 maxillary and mandibular complete dentures were made using light-body polysulfide rubber. The number of adjustments required over 1 year was recorded. No statistical difference in adjustments was noted between the two groups.

Laboratory accuracy in casting removable partial denture frameworks

An attempt was made to compare the clinical accuracy of two types of cast metals used in the fabrication of removable partial dentures as they were prepared by commercial laboratories. No comparison of the metals could be made, because the discrepancies that were found were too gross and were related to technical error. Suprabulge clasps were placed in less undercut than prescribed. Infrabulge clasps were placed in more undercut than prescribed. The laboratories produced better accuracy when they were informed of the purpose of the cast frameworks than when the frameworks were made without the knowledge that their work would be tested. One laboratory produced better results than the other under similar conditions.

Retention of obturator-removable partial dentures: A comparison of buccal and lingual retention

An in vitro study was performed to measure the influence of a simulated obturator on the amount of force required to dislodge a simulated unilateral removable partial denture with various clasp designs. The presence of an obturator reduces the retentive capability of a removable partial denture. Lingual retention appeared to provide more resistance to displacement than buccal retention. Infrabulge clasp designs appeared to be more retentive than suprabulge clasp designs.

Cranioplasty of the difficult frontal region

Abstract Problems associated with performing a cranioplasty on the difficult frontal region were discussed. As many of the problems are related to the materials available, the advantages and disadvantages of the more popular classes of materials used in a cranioplast were indicated.