Donald L. Mitchell

A photoelastic study of stress induced by framework design in a maxillary resection

Support of a framework and obturator in a patient with an acquired maxillary defect is diminished by the removal of a portion of the palate and alveolar bone. The intent of this study was to investigate, by three-dimensional photoelastic analysis, the stress transmission that occurs with four commonly used retentive systems. The individual designs were facial cast circumferential retention with palatal plating, swing-lock design with palatal plating, facial cast circumferential retention and palatal cast circumferential clasp reciprocation, and facial cast circumferential reciprocation with palatal I-bar retention. Stresses were observed and compared on the palate and around the teeth of the four models.

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.

Inverted anatomic tracing: A guide to establishing orbital tissue contours for the oculofacial prosthesis

A technique is described to aid the maxillofacial prosthetic technician in contouring an oculofacial prosthesis. This technique should reduce clinical time and improve prosthesis results.

Radiographic comparisons of condyle-fossa relationships during maxillomandibular registrations made by different methods.

Abstract The condyle-fossa relationships were compared when maxillomandibular registrations were made in centric relation, with the teeth intercuspated and by muscular stimulation methods. The relationships of the condyles to the glenoid fossae established by each method were determined radiographically and compared on composite tracings. Analysis of the tracings indicated that the condyles were in a central position in the glenoid fossae in 21 of the 30 tracings. Both the intercuspation and centric relation methods caused the condyles to be centered in the fossae in eight of ten subjects. The muscular stimulation method caused the condyles to be centered in the fossae in five subjects and positioned anteriorly in the fossae in five subjects.

The orbital shell: An aid in positioning the ocular component and verifying margin contours for oculofacial prostheses

The correct location of the orientation (conversational gaze) of the ocular component is vital to esthetically pleasing oculofacial prostheses. This location should be verified before time and energy are spent on sculpturing the oculofacial prosthesis. A technique is described that uses a clear acrylic resin shell as a matrix and Play-doh material as a support medium to position and support the ocular component to verify the orientation. In addition, the thin acrylic resin shell can be used to refine border inaccuracies that may exist clinically.

A photoelastic study of rests on solitary abutments for distal-extension removable partial dentures

With a distal-extension removable partial denture, maximum use of existing oral structures can aid in the total support of the prosthesis and reduce the force on the solitary abutment. Four rests with relieved and unrelieved guide plates were evaluated for optimum stress distribution around the root of a solitary premolar abutment. These rests were the mesial, the distal, the mesial and distal, and the continuous rest. The findings demonstrated that The continuous rest had the most favorable stress concentration. All other rest designs demonstrated more lateral stress than the continuous rest. Relieved guide plates demonstrated 58% less maximum shear stress in the apical portion than unrelieved guide plates.

Rehabilitation of a patient with a bilateral partial maxillary resection. A clinical report

T he complete absence of the hard and soft palate creates a special problem in the rehabilitation of a patient with a bilateral partial maxillary resection. Thii situation will challenge the ability of the maxillofacial prosthodontist because of the unique type of support, stability, and retention requirements for the prosthesis.lb3 Although the size of the defect can vary superiorly and posteriorly there is commonly an absence of remaining structures to aid the support, stability, and retention of a prosthesis. After placement of a skin graft and postoperative radiation, insertion of a prosthesis can be complicated