James S. Brudvik

Clinical evaluation of patients eight to nine years after placement of removable partial dentures

Removable partial dentures, constructed following principles outlined in this study, provided reasonable service for an 8- to 9-year period for patients who were wearing them. The oral hygiene of the patients was less than ideal. Few teeth were lost by patients in the study. There were no significant differences in caries incidence, changes in sulcus depths, tooth mobility, or alveolar bone loss between patients who were wearing their dentures and those who were not. There were increased levels of gingival inflammation seen in regions covered by the removable partial dentures and in gingivae apical to clasp arms. Other than these findings, there seemed to be no direct evidence that the removable partial dentures were causing dental or periodontal breakdown.

Relationship between the standards of removable partial denture construction, clinical acceptability, and patient satisfaction

STATEMENT OF PROBLEM Little is known about the importance of published fabrication standards in determining the outcome of treatment with mandibular distal extension removable partial dentures in patients of community practices. PURPOSE This study describes mandibular partial dentures worn by patients from King County, Wash., and examines the validity of standards of design and fabrication by relating the standards to measures of clinical acceptability and patient satisfaction. MATERIAL AND METHODS Eighty-two people treated in private dental practices who responded to a mail survey about satisfaction with a partial denture were examined. Eight standards of fabrication, overall clinical acceptability of the prosthesis, and tissue health were evaluated clinically. Patient satisfaction was assessed by questionnaire. Associations between variables were assessed by contingency tables and odds ratios. RESULTS Half the prostheses met 4 or fewer of the 8 standards, and these were responsible for nearly all the displacement of tissue by the framework. Forty-three percent of the dentures (35/82) were rated clinically acceptable. Of the remaining dentures, 38 could be made acceptable by modifications. The remaining 9 dentures needed replacement. Sixty-three percent of the patients examined were satisfied with the dentures. There was a relationship between tissue health and the fabrication standards related to rest form, base extension, stress distribution, and framework fit. This study found no relation between tissue health and other design or fabrication features. None of the standards were found to be related to patient satisfaction. CONCLUSION This study found partial support for the validity of design/fabrication standards for removable partial dentures. The most important standards are rest form, base extension, and stress distribution. The standards appear to be unrelated to patient satisfaction.

Evaluation of hard direct reline resins.

Peak curing temperatures of hard, direct, autopolymerizing reline resin materials tested were all within ADA specification guidelines. A temperature range of 10 degrees C was demonstrated among materials, with the highest polymerization temperatures recorded for Perm and Langs Self-Curing Rebase Acrylic, and the lowest for KOOLiner, Flexacryl, and COE-Rect. This temperature difference is probably clinically detectable. However, intraoral testing of polymerization temperatures yielded lower peak values than those observed with specification testing, and the temperature peaks occurred earlier with intraoral conditions. There were significant color changes with simulated aging for three of the products tested: Flexacryl, COE-Rect, and Langs Self-Curing Rebase Acrylic. The color changes occurred after only 24 hours of accelerated aging. Although there was only a small change in color with aging for Perm and KOOLiner, there was a moderate shift in the color of KOOLiner (delta E = 2.2) before aging. Thus only Perm demonstrated little color change with simulated aging. Of the reline products, one material, KOOLiner, demonstrated lower bond tensile strengths to denture base materials. However, the clinical significance of this was not known. One denture base material (Astron) recorded significantly higher bond strength values for all reline products and failure always took place within the denture base.

Clinical evaluation of removable partial denture rest seat adaptation

The clinical relationship between the removable partial denture cast occlusal rest and the corresponding rest seat was examined. Under the conditions of the study, it was found that rests of mandibular Class I and II removable partial dentures fit significantly better than those of mandibular Class III and IV prostheses. No significant difference was noted between similar types of maxillary removable partial dentures in this regard. In evaluating the fit of specific portions of the occlusal rest, it was found that the marginal ridge zone was more closely adapted to the rest seat than other zones for all types of removable partial dentures. However, contact, as defined in this analysis, was found to exist on a random basis in all four quadrants of the occlusal rests evaluated. In spite of this fact, one fifth of the occlusal rests did not contact the opposing rest seat at any point. Improved fit with length of service was not substantiated by a cross-sectional analysis. Suggestions were made to assist the clinician in achieving a better fit between the framework and dentition in removable partial dentures.

In vitro two-body wear of inlay-onlay composite resin restoratives.

Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resins using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surface was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.

The tooth-removable partial denture interface

During the metal finishing phase of removable partial denture construction, metal is removed from all aspects of the casting. The amount removed from areas designed to contact prepared surfaces of abutments is critical to the resulting fit of the partial. Castings were evaluated before and during finishing procedures to measure metal loss at the tooth-removable partial denture interface. Finishing and fitting techniques for controlling the loss of metal are presented.

Stress-relaxation testing. Part IV: Clasp pattern dimensions and their influence on clasp behavior

Harold F. Morris, D.D.S., M.S.,* Kamal Asgar, Ph.D.,** James S. Brudvik, D.D.S.,*** Sheldon Winkler, D.D.S.,**** and Eugenia Popescu Roberts***** Veterans Administration Medical Center, Allen Park, Mich.; University of Michigan, School of Dentistry, Ann Arbor, Mich.; LJniversity of Washington, School of Dentistry, Seattle, Wash.; Temple University, School of Dentistry, Philadelphia, Pa.; and University of Detroit, School of Dentistry, Detroit, Mich.

Stress-relaxation testing. Part III: Influence of wire alloys, gauges, and lengths on clasp behavior

Commonly used, commercially available dental wires have been evaluated and ranked through stress-relaxation testing to given the clinician a basis for determining their use as retentive clasp arms. Clinical laboratory principles relative to the use of wire clasp arms have been discussed. Clinical experience with the cobalt-chrome-nickel wire retentive clasp arms used in the infrabulge approach over the last 8 years has been rewarding. These wire clasps have been every bit as effective as the cast bar clasps and have proven to be superior in terms of adjustability and resistance to fracture. The relation of active clasp length to retention and permanent deformation is a crucial one and should be a component of every philosophy of design and construction of removable partial dentures.

A comparison of the flexibility of wrought wire and cast circumferential clasps

M any dentists use wrought wire clasps instead of cast circumferential clasps on abutment teeth for distalextension removable partial dentures. The flexibility of the wrought wire clasp is believed to reduce transmission of excessive force to the abutment tooth.’ Recent investigations have compared the flexibility of various wrought wires and nickel-chrome-cobalt alloys commonly used for clasp construction. Morris et al.’ developed a stiffness index by testing clasps with a stress-relaxation cycling instrument. The index allows the stiffness of clasps to be compared regardless of dimension, form, or material. Brudvik and Morris3 tested six wrought wires including two different alloys and several gauges. Stress-relaxation cycling was used to determine the stiffness of the specimens. In a later study, Morris et aL4 found that the stiffness of cast circumferential clasps was greatly influenced by the width/thickness ratio of the clasp. A study by Frank and Nicholls5 ranked 16 precious and nonprecious wrought wires according to their flexibility. Each clasp sample was displaced one time until the proportional limit was exceeded. Twentygauge wires were found to be twice as flexible as l&gauge wires. Flexibility values also diKered due to the various alloys used in manufacturing the wires. Several wrought wires were tested independently by both the stress-relaxation cycling and the singledisplacement methods. Although the values for stiffness and flexibility cannot be compared directly, each method resulted in the same ranking of the clasp samples. The purpose of this study was to compare the flexibility of several forms of cast nickel-chrome and cobalt-chrome clasps with that of wrought wire clasps. Round and half-round forms were selected. The single-

Adaptation of a visible light-cured denture base material

The Triad light-cured resin system appears to have potential for making processed record bases for special patients. The close adaptation of this material to the dental cast often results in internal voids and defects. These defects are greatly reduced when a dry cast is used instead of one with a high moisture content. Vacuum-assisted adaptation using a sheet of rubber dam in connection with a vacuum adaptor also results in an improved internal surface. Finger pressure alone is not a dependable method of adaptation.