Surgical template for completely edentulous patients.

Implant angulation is of utmost importance for fabrication of esthetic, hygienic, and functional prostheses, even in the treatment of completely edentulous patients. Most mandibular surgical templates are not reliable because of a lack of stability resulting either from severe resorption of the mandible or from the interference of mucoperiosteal flaps elevated during surgery. This article describes a technique for fabrication and surgical application of a stable template for the completely edentulous mandible. By combining the mandibular template with a maxillary duplicate denture, the problem of lack of stability can be overcome. A consistently reliable reference for implant placement in the edentulous mandible, specifically in relation to implant angulation (trajectory), can be obtained.

The swing-lock removable partial denture in clinical practice.

The authors of this article consider that the swing-lock partial denture has a useful place in contemporary clinical dental practice and offers many advantages compared with conventional removable partial dentures in terms of retention and stability, especially in the extremely compromised dentitions. Here they describe the concept of the swing-lock removable partial denture, together with the indications, contraindications, technical and clinical considerations.

Influence of polishing on cast clasp properties.

During the polishing of clasps, two possible changes that could affect their properties are thinning of the clasp and work hardening of the alloy. Two distinctly different clasp pattern forms were selected and 20 samples of each were cast. They were then divided into two groups, polished and unpolished, in an effort to determine the total influence of the polishing procedure on clasp behavior. The results indicate that polishing produces a slightly more flexible clasp. Any influence resulting from possible work hardening is offset by the reduction of clasp thickness. Effects of width/thickness ratios and magnitude of deflections on finishing and polishing techniques may also alter clasp flexibility in the polished clasp.

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.

A new procedure to reinforce fixed provisional restorations.

The typical unreinforced fixed partial denture provisional restoration commonly fails because of fractures and loss of cement retention. A procedure to reinforce the provisional restoration with a substructure of orthodontic band material has dramatically increased the longevity of this restoration. The procedure requires commonly available materials without a significant increase in cost or construction time.

Soldering of removable partial dentures.

Both high- and low-heat removable partial denture alloys were soldered with combinations of different solders and heat sources. The soldered specimens were subjected to tensile strength testing, and a ranking of joint strength was developed. Joint strengths that were 85% as strong as the as-cast metal were created in both alloy types when 0.800 fine solder was used with an electrosoldering device as a heat source. All other combinations tested resulted in greater reductions in joint strength.

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.

Adult palatal expansion prostheses.

The technical steps in the construction of two types of adult palatal expanders have been described. These prostheses are complex and require a special level of coordination between the professional team and the dental laboratory. The teamwork involved in the restoration of major maxillary defects contributes to the success of the prosthesis and makes the efforts involved worthwhile.

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.

Evaluation of eccentric occlusal contacts in complete dentures.

Three edentulous patients were evaluated using the kinesiograph and a specially designed computer program to identify the length of eccentric contacts between their dentures when masticating test foods. Three different interchangeable occlusal arrangements were constructed and tested. Results of the evaluation of more than 1,400 chewing cycles showed that while 25% of masticatory contacts were eccentric, the great majority of contacts were within a distance of 1 mm from centric occlusion. More eccentric contacts occurred in the opening phase than might be expected. Posterior tooth form did not appear to affect the range of eccentric contacts.

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.

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 Lang's 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 Lang's 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.

Frictional resistance of removable partial dentures with retrofitted resin composite guide planes.

Frictional resistance to the dislodging forces of a removable partial denture with and without resin composite retrofitted guide planes was compared in vitro. Six master models of four natural teeth, each simulating a Kennedy Class III modification 1 arch, were used. Guide planes were prepared, and 18 cobalt-chromium removable partial denture frameworks without clasps were fabricated. Three resin composite materials were applied to the guide planes as retrofitting materials. Following this, the resistance to dislodgment of the removable partial denture framework was evaluated under cyclic dislodgment, and the resistance to dislodgment before and after resin composite retrofitted guide planes was compared. The dislodgment force was recorded every 500 cycles. Testing was concluded when the dislodging force value reached 50% of the initial value. There was a significant difference between the dislodging forces with and without retrofitted guide planes. Higher dislodging forces were recorded when resin composite retrofitted guide planes were used. Z100 was the most effective retrofitting material under cyclic dislodgment, and Heliomolar and Herculite XR performed similarly.

Porcelain occlusal posterior fixed partial dentures.

A method for using the functionally generated-path technique to fabricate full occlusal porcelain-fused-to-metal fixed partial dentures and crowns has been described. Proper use of this technique in carefully selected patients should eliminate occlusal adjustments and the concomitant polishing and glazing that are often necessary before the restoration can be permanently cemented.

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.

The effect of dentin primer on the tensile bond strength to human enamel.

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.

Accuracy of replacing three tapered transfer impression copings in two elastomeric impression materials.

The accuracy of replacing three manufacturers' (Dental Imaging Associates, Implant Innovations Inc, and Steri-Oss) tapered transfer impression copings into impressions made with two different materials (Impregum F and Extrude) was evaluated. Five operators replaced these copings into the elastomeric impression materials. The angular deviations (replacement error) of the copings between the control (original) position and the replaced position in the impressions were evaluated. It was found that no one coping could be replaced into the impressions accurately and consistently by all five operators. However, there were significant differences in replacement accuracy between the three copings. Lower angular deviations were found for the Steri-Oss and Dental Imaging Associates copings when compared to the Implant Innovations coping. There was no significant difference in replacement accuracy between the two impression materials.

Evaluation of heat-cured resin bases following the addition of denture teeth using a second heat cure.

This study compared heat-cured acrylic resin denture baseplate distortions following a second heat cure used to add the denture teeth. The second heat cure was done with three different water-bath curing temperatures. The distortions were evaluated in three planes by use of a measuring microscope. Recorded distortions were not clinically significant.

Influence of reinforcement design on the loss of marginal seal of provisional fixed partial dentures.

Loss of marginal cement seal, initial fracture, and stiffness of three four-unit provisional restorations were tested. Loss of marginal cement seal was monitored using strain gauges located occlusogingivally at the distal of the second molar abutment and the mesial of the first premolar abutment of a four-unit posterior fixed provisional restoration with two pontics. The provisional restorations were then placed in an Instron testing machine and loaded to initial fracture. Stiffness was calculated from the Instron recordings. The provisional designs were permachrome band-reinforced, wire-reinforced, and a nonreinforced control. Analysis showed: (1) the band-reinforced design withstood a significantly greater load before loss of cement seal (P< or =.05); (2) the band-reinforced design had a significantly higher stiffness (P< or =.05); and (3) there was no difference between the three designs for load at initial fracture. Within the same sample it was found that for both band- and wire-reinforced designs the premolar abutment lost the marginal cement seal at a significantly lower load than the molar (P< or =.05). For the control there was no significant difference for load at marginal cement seal loss between abutments.

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.