Using the neutral zone to obtain maxillomandibular relationship records for complete denture patients.

A technique for obtaining maxillomandibular registration for complete denture patients is presented. The maxillary rim is formed with the use of conventional techniques. The mandibular rim is made from modeling plastic impression compound on a record base formed by the patient into the neutral zone. The mandibular rim then is reheated, and the patient determines the occlusal vertical dimension by swallowing. An imprint of the maxillary rim is made on the mandibular rim at the occlusal vertical dimension. The posterior extent of the mandibular rim is relieved 1 mm. Orientation notches are placed in both rims, and centric relation is recorded with a fast-setting vinyl polysiloxane material.

Measurement of hydrostatic pressures during simulated post cementation.

Tooth sensitivity and fracture after cementation of posts for endodontically treated teeth have been a problem. This investigation developed an in vitro method of measuring intraradicular hydrostatic pressures created during simulated post cementation. The testing apparatus consisted of a pressure transducer and brush recorder connected to precision milled post spaces in a Plexiglas block. Cast post and cores were fabricated and cemented with three different luting agents: resinous cement, glass ionomer cement, and zinc phosphate cement. Mean hydrostatic pressures (psi) recorded during post cementation were zinc phosphate cement, 22.67; resinous cement, 19.77; and glass ionomer cement, 17.66. Zinc phosphate cement created substantially greater hydrostatic pressures than either the resinous or glass ionomer cements. This in vitro system was capable of discriminating intraradicular hydrostatic pressures among different classes of luting agents.

Occlusal trauma: a case in perspective.

The decision to initiate occlusal therapy as part of periodontal treatment is often controversial. This case report illustrates an indication for providing such therapy and suggests an appropriate sequence to follow for achieving a desirable outcome.

Comparison of vertical movement occurring during loading of distal-extension removable partial denture bases made by three impression techniques.

Although the altered-cast impression technique attains stability and controlled tissue support for distal-extension removable partial dentures, the procedure is time-consuming and technique-sensitive. This study clinically compared the vertical displacement of distal-extension removable partial dentures made from different impression techniques. The impressions studied were the altered-cast impression, an impression made from a border-molded custom tray, and a stock tray irreversible hydrocolloid impression that served as a control. A post hoc analysis, using a Tukey Q-test, exhibited significance (p less than 0.01) between the two impression techniques after intraoral loading was performed. Although statistically significant, the 0.19 mm difference between the impression techniques may or may not be clinically relevant. Additional research is required in this area.

Etched castings as an adjunct to mouth preparation for removable partial dentures.

Electrochemically etched nonprecious metal castings have been bonded to etched enamel for use in mouth preparation procedures for removable partial denture placement. The castings have been in service and subject to loading by the dentures for 26 to 42 months. To date, bond strengths have been sufficient to support function of both castings and removable partial dentures clinically. None of the castings has failed in its bond. Evidence that the technique may be a valuable adjunct is building in the field of prosthodontics. Use may be far reaching as dentists apply the concept to a wide variety of patient requirements in dental treatment. As more commercial dental laboratories acquire the capability to etch metals, cost should be minimized. Application is not time-consuming. Some steps are technique-sensitive, however, and short cuts are not well tolerated. This is especially true of cementation procedures where moisture or contamination of the field may lead to failure of the bond. It should be noted that each nonprecious metal is different from other metals in its composition, and therefore, results and techniques reported in this study can only be cited for the metal used. In addition, the acid used for etching one alloy may not be effective on another alloy. Finally, it is important that all castings be checked under a binocular microscope to ensure that proper etching did occur. Underetching and overetching both lead to a weakened bond and potential failure.

Prosthodontic considerations for patients undergoing cancer chemotherapy.

Dentures for the patient receiving cancer chemotherapy must be constructed and maintained carefully, using sound basic principles of denture construction and tissue management inherent in the highest level of prosthodontic treatment. The objective of removable prosthodontic therapy is to improve the patient's quality of life, enhance nutrition by reducing oral irritation and ulceration, and control the oral microbial populations associated with chemotherapy and the wearing of a denture.

Rest vertical dimension determined by electromyography with biofeedback as compared to conventional methods.

This study was undertaken to determine if electromyography with biofeedback can be utilized to produce a more reliable determination of rest vertical dimension than conventional methods such as phonetics and swallowing. It was found that: 1. Electromyography with biofeedback appeared to produce a more consistently reliable determination of rest vertical dimension than conventional methods when used with edentulous subjects. 2. Determinations of rest vertical dimension by individual dentists using phonetics and swallowing had wide variations in two of the five patients in a range of up to 6 mm. An error of this magnitude could easily cause an intrusion upon the interocclusal distance and resultant failure of treatment. Since this study was limited to five patients, a more expanded study is necessary to determine the validity of electromyography vs. conventional methods for determining rest vertical dimension. Both methods have questionable aspects in relation to the time of day, patient's understanding of each technique, and past dental history. However, the most critical problem of the electromyographic technique is the feasibility of its use in a private practice in light of the excessive cost of the required equipment.