Dorsey J. Moore

Evaluation of polymeric materials for maxillofacial prosthetics

The methods for initial evaluation of a new prospective maxillofacial prosthetic material, MDX-4-4210, have been described and tensile and compressive test data have been obtained. Evaluation of the data indicates that this is a promising material with significant potential for use in maxillofacial prosthetics. Further studies of the materials biologic implant compatibility, its chemical and environmental stabilities, and its clinical performance are being done.

Glossectomy rehabilitation by mandibular tongue prosthesis

Abstract In the rehabilitation of patients following complete glossectomy, the early placement of an obturator to assist in deglutition and articulation has proved to be effective. The tongue is not absolutely necessary in the production of speech. In all glossectomy patients, though, there seems to be a reluctance to try to speak or take oral fluids after the operation. Tongue prostheses constructed in conjunction with mandibular removable partial dentures, with the tongue portion in an elevated position, give patients the additional help needed to overcome this initial reluctance. The patients are able to quickly regain their speech and swallowing abilities. A tongue prosthesis can speed the recovery of patients and return them to society to enjoy a nearly normal diet and speak understandably without a tongue.

A diagnostic craniometric method for determining occlusal vertical dimension.

There is no precise scientific method for determining the correct edentulous occlusal vertical dimension. This study established the proportion between the ear-eye to chin-nose distance for determining reasonable occlusal vertical dimension. Two hundred white and 400 Asian men and women participated in this study. The ear-eye and chin-nose distances were measured with a modified craniometer. The results revealed that left ear-eye distance can be used to predict chin-nose distance with reasonable accuracy. However, the algorithm for making this prediction is not the same for combinations of sex and ethnic origin.

Comparison of the physical properties of two types of polydimethyl siloxane for fabrication of facial prostheses

The in vitro physical properties of two types of polydimethyl siloxane, MDX 4-4210 and a new material A-2186, were compared. The properties that were investigated in this study were tensile strength, elongation, tear strength, and surface hardness. The properties tested were selected because of their clinical significance for fabricating a facial prosthesis. According to the results obtained in this investigation, the new material, A-2186, had greater tear resistance, tensile strength, and a larger percentage of elongation. A-2186 material, also proved to be softer at the surface than the MDX 4-4210. This combination of physical properties makes this material, A-2186, a better choice than the traditional MDX 4-4210 for the fabrication of facial prostheses.

Rehabilitating dentulous hemimandibulectomy patients

A hemimandibulectomy can have many debilitating consequences, such as an eccentric occlusion, a disoriented masticatory cycle, facial disfigurement, distorted speech, and salivation problems. If prosthetic treatment begins some time following surgery and the cicatricial tissue has already consolidated, additional treatment time is necessary. A technique is described which combines crowns with a maxillary prosthesis to guide the mandible into a functional occlusion.

Stereophotogrammetric analysis of abutment tooth movement in distal-extension removable partial dentures with intracoronal attachments and clasps

This study applied the three-dimensional measurement technique of stereophotogrammetry to measure abutment tooth movement under occlusal loading as a function of intracoronal attachment and clasp design. Six distal-extension removable partial denture designs were studied: (1) RPI-mesial occlusal rest, proximal plate, buccal I-bar; (2) cast circumferential clasp; (3) P.D. locking semiprecision attachment; (4) Thompson dowel nonlocking semiprecision attachment; (5) McCollum precision attachment; and (6) Stern G/L precision attachment. The movement in microns was determined by computer analysis. The Thompson dowel semiprecision attachment generated the most abutment movement in a gingival direction. The clasp-retained designs generally had less total movement than the attachment designs. Clasps and attachments for the abutment teeth adjacent to the distal-extension bases generally moved more than the abutment teeth.

Prosthetic treatment of the laryngectomized patient

Abstract Methods have been presented that will enable the maxillofacial prosthetist to assist in the treatment of the laryngectomized patient. These include construction of a custom laryngectomy tube of silicone rubber that will aid in preventing stenosis of the stoma while minimizing complications and adding to patient comfort. Vocal rehabilitation of the laryngectomee is the most important aspect of postoperative therapy. The learning of alaryngeal speech may be complicated by neuromuscular deficiencies or anatomic limitations resulting from the surgical procedure. A prosthetic speech aid can benefit some of these patients by maintaining pressure on the pharyngeal segment of the esophagus to increase voice volume and minimize air expenditure.

Assessing shade differences in acrylic resin denture and natural teeth

Four experiments in this study assess shade differences in acrylic resin denture and natural teeth. The first two examine the perceptual errors made by experienced dentists in their use of a manufacturer-provided shade guide for acrylic resin denture teeth. In the first of four experiments, dentists examine whether the numbering of a selected shade guide corresponds to the arrangement of the tabs from light to dark. In the second experiment, a visual discrimination task determines whether dentists can distinguish shade guide tabs from one another. The results from these two experiments revealed that the numbered progression of the shade tabs does not correspond to a light-to-dark order, that dentists have difficulty discriminating between several shade tabs, and that the shade tabs can be rearranged on an empirical basis. The third experiment demonstrated how the shade of natural teeth varies by age, gender, and complexion. The Biotone shade guide, rearranged in the manner suggested by the second experiment, was used to make these assessments. The fourth experiment examined whether the shades used for complete dentures were similar to shades found in natural teeth. The results from the last two experiments showed that shade selection can be facilitated by use of a rearranged set of shade guide tabs. The results also reveal that natural teeth significantly and clinically darken with age; however, selections made for denture teeth tend to be relatively constant in color, despite the age of the patient. Differences for gender and complexion do not appear to be clinically significant.

Sterilization of impression materials for use in the surgical operating room

Abstract In this study, 30 samples of one type of irreversible hydrocolloid powder and 30 samples of one type of plaster material were effectively sterilized using gaseous ethylene oxide. The procedure did not adversely affect the setting time or the dimensional accuracy of the hydrocolloid material.

A radiographic grid for contouring cranial prostheses

Abstract A procedure for producing an acrylic resin cranial prosthesis has been described. Radiographs of a metal grid positioned on the patients head over the defect provide a key to the precise location of the bony margins of the defect to be repaired. Transfer of measurements from the radiographic alignment grid ensure the development of a pattern that meets all requirements established for this procedure.