A seminar/case-based approach to teaching removable partial dentures to predoctoral students.

This article describes a seminar/case-based, instructional model designed to simulate removable partial denture (RPD) problem-solving and decision-making processes encountered in third-year clinic in dental school and in dental general practice. Groups of approximately 20 second-year students (in the 3-year program) meet in a series of six 1-hour seminars during the first days of the course. Following the seminars, students complete an exercise on mouth preparation and multiple clasp and major connector designs on prototype casts. This is followed by survey-design exercises on casts of dentitions representing six variations of RPD requirements. Instructors assist students during the practice phase of each class. Each 2-hour practice session is followed by a 1-hour practical examination. The last day of the course is devoted to a comprehensive final practical examination on both maxillary and mandibular casts, incorporating any of the design features previously studied.

Denture tooth selection: size matching of natural anterior tooth width with artificial denture teeth.

This project, conducted by the Removable Prosthodontic faculty, compared the mesiodistal widths of the six maxillary anterior teeth with the widths of denture teeth from six different denture tooth manufacturers. Four hundred eighty-eight casts of dental students were measured from the distal aspect of each canine across the facial surfaces of the six anterior teeth with a flexible plastic millimeter rule. Denture teeth from six manufacturers were compared (370 molds). The results indicated that denture teeth are predominantly smaller and natural teeth are larger.

Clasp retention: the effects of five variables.

An attempt was made to determine the relative retention of each of the four most commonly used clasp assemblies. They are the rest, proximal plate, I bar (RPI); rest, proximal plate, facial circumferential arm (RPA); modified T; and Akers (facial and lingual circumferential arms). A mandibular bilateral distal extension base removable partial denture design was selected because it is most commonly used. A test model was made by removing all mandibular molars from a Columbia Dentoform and replacing the ivorine second bicuspids with natural teeth. These, in turn, were later replaced with gold crowns that were identical in contour to the natural teeth. Eight removable partial dentures were constructed using preformed plastic lingual bars, minor connectors, denture base retention loops, and clasps. Artificial teeth and the denture bases were processed to each framework as for a clinical patient. Each removable partial denture was placed in the Instron testing machine and pulled from the test model. The investigation examined the effectiveness of each of four types of clasps in resisting displacing forces, in both vertical (occlusal) and mesio-occlusal directions. Each clasp was tested using natural teeth and gold crowns, in dry and wet environments, both with and without indirect retainers. Results indicate that, (1) The RPA clasp was the most retentive of all on natural abutments, against both directions of pull, but only slightly so over the RPI clasp with a vertical pull. (2) The Akers clasp was most retentive against a mesio-occlusal pull on the gold abutments. (3) Natural tooth structure gives slightly more frictional resistance than a gold surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Denture tooth selection: an analysis of the natural maxillary central incisor compared to the length and width of the face: Part II.

This is the second part of a project conducted by the Removable Prosthodontic Faculty to compare the length and width of the maxillary central incisor with the length and width of the face. In this article, gender of the students was the main consideration. Three hundred fifty men and 138 women students participated in the project.

Denture tooth selection: an analysis of the natural maxillary central incisor compared to the length and width of the face. Part I.

A project was devised by the removable prosthodontic faculty to determine clinically if there is a correlation between the length and width of the maxillary central incisor on a cast and the length and width of the face. A millimeter gauge was used to measure the lengths and widths of the maxillary incisor on a cast. The Trubyte tooth indicator was selected to measure the length and width of the face. This tooth indicator is designed for calibration of the 16 to 1 ratio between facial dimension and maxillary central incisors.

Cross-arch bar splint.

This article describes the use of a round bar connector that will aid the preservation of bone support for two isolated mandibular canines when a fixed partial denture replacing the anterior teeth is contraindicated. If the removable partial denture is constructed with only the two lone-standing canines as abutments, the removable partial denture will move occlusally and gingivally during function, thereby generating forces that may cause bone loss. By the addition of a straight round bar connecting the two canine crowns, the abutments are splinted together and masticatory forces are directed along the long axes of the teeth.

A simplified procedure for survey and design of diagnostic casts.

The procedure described for survey and design of diagnostic casts is applicable to either dental arch. It is presented in a sequential manner, is not complex, and will produce uniformly acceptable results. The following steps should be followed: (1) locate a path by tilting the cast; (2) mark the survey lines and tripod the cast; (3) outline the rest and guide planes; (4) draw minor connectors; (5) draw major connectors; (6) draw retention mesh for acrylic resin; (7) draw acrylic resin base extension; and (8) draw direct retainers (clasps).

An individualized impression tray utilizing the patient's existing denture.

This technique utilizes patients' existing dentures to construct individualized impression trays. Some of the advantages are: (1) the trays are made within 30 minutes; (2) final impressions may be made at the first appointment; (3)it is an inexpensive and uncomplicated laboratory procedure readily taught to dental auxiliaries. (4) chair time is better utilized by both the dentist and patient.