The effect of custom tray material type and fabrication technique on tensile bond strength of impression material adhesive systems.

The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray materials [autopolymerizing and visible light-cured (VLC) acrylic resin]. The effect of polymerizing the tray materials directly against wax spacer and tin foil was evaluated for each material. Polymerizing tray materials against tin foil significantly increased the bond strengths of polysulphide and polyvinyl siloxane impression materials to VLC and autopolymerizing acrylic resin tray materials. Polyvinyl siloxane VLC cured against tin foil combination produced the strongest bond. The VLC resin tray material generated greater bond strength than autopolymerizing acrylic resin when polymerized against tin foil.

Repair of denture base resins with visible light-polymerized reline material: effect on tensile and shear bond strengths.

STATEMENT OF PROBLEM: Triad visible light-polymerized (VLP) reline resin has the potential to repair denture bases from other resin systems with the elimination of flasking/deflasking procedures. PURPOSE: This study measured the tensile and shear bond strengths of Triad VLP, PMMA, and glass-fiber-reinforced PMMA (GF-PMMA) acrylic resins before and after repair with Triad VLP reline material. MATERIAL AND METHODS: Fifty-six specimens were fabricated from Triad VLP, PMMA, and GF-PMMA denture base resins. Both Triad VLP reline material and autopolymerizing acrylic resins were used to repair identical laboratory fabricated resin joints. Twenty-eight rectangular specimens (in 4 different groups of 7 each) were prepared to study the shear bond strength of Triad reline material used to repair different denture base resin joints. RESULTS: Statistically significant differences (P< .0001) were found between the tensile strengths of specimens repaired with the Triad VLP reline resin used as a repair agent and those repaired with the autopolymerizing resin. The tensile strength of the Triad VLP denture base resin was found to be higher than that of both the PMMA and GF-PMMA acrylic resins. CONCLUSION: The low tensile and shear bond strengths found after the repair of PMMA and GF-PMMA acrylic resins with Triad VLP reline material were attributed to a lack of cohesion/adhesion between the Triad VLP reline material and the interfaces of the treated sites. The use of Triad VLP reline material to repair Triad VLP denture base resin produced the highest strengths.

Classic symptoms in temporomandibular disorder patients: a comparative study.

Numerous symptoms have been reported in the literature associated with temporomandibular disorders (TMD). However, it has not been stated what TMD symptoms are the most important and consistent and in turn, can be referred to as the gold standard or classic symptoms. The purpose of this study was: 1. To review the literature regarding TMD symptoms; 2. To compare so-called classic TMD symptoms with the symptoms of patients diagnosed as having TMD. Out of 52 consecutive patients, 40 were diagnosed as having TMD and were selected for this study. Forty non-TMD subjects served as a control group. A total range of subjective symptoms, from a self-administered TMD history form, was collected, but only so-called classic or the most common TMD symptoms were reported in this study. Results revealed that the major complaints of the TMD patients, including headaches, were similar to the suggested classic TMD symptoms derived from the literature.

Pattern waxes and inaccuracies in fixed and removable partial denture castings.

It is the desire of every dentist and dental technician to produce a restoration that will fit the patient with a minimum of adjustments and certainly one that does not require remaking. Yet many abuse the materials with which they work, either through improper manipulation, lack of familiarity with their properties, or by attempting to reduce laboratory time by taking short cuts. Wax is one of the materials that requires more knowledge and skill to manipulate accurately because it has a considerably higher coefficient of thermal expansion (and contraction) than any other dental material. It often contributes considerably to the inaccuracies of cast dental restorations. This article provides a review of dental waxes used to make prosthodontic castings and points out some of the properties of waxes that must be controlled to make accurate restorations.

The effect of storage time of removable partial denture wax pattern on the accuracy of fit of the cast framework.

STATEMENT OF PROBLEM: Situations may arise in dental laboratories that could result in a time lapse between preparing the wax pattern of the removable partial denture framework and its casting into the cobalt-chromium alloy. PURPOSE: This study investigated the effect of storage time of the wax pattern before casting and the influence of the palatal major connector design on the accuracy of its fit on the master casts. MATERIAL AND METHODS: Forty-two frameworks were prepared with two designs of major connectors, which were divided into three subgroups according to the storage time of the wax patterns: 24 hours, 1 week, and 1 month. Discrepancies in the fit of the connectors to their respective casts were measured at specific locations for both connector designs. RESULTS: In both framework design groups, there was a significant deterioration in fit (p < 0.0005) of the major connectors with the increase in storage time of their wax patterns on their respective refractory casts. Gap discrepancies were more pronounced towards the center of the palate. CONCLUSIONS: The greatest discrepancies appeared at the middle sections of the connectors more than at the lateral section (p < 0.0005). Furthermore, frameworks with modified palatal plate major connectors exhibited greater inaccuracies in their fit than those with the anterior posterior palatal strap design, as evidenced by the increase in mean gap discrepancies under the palatal plate design (p < 0.0005).

Designs of bond strength tests for metal-ceramic complexes: review of the literature.

Despite the popularity of metal-ceramic restorations, the bonding mechanism remains the subject of theoretical discussion. Different experimental designs to evaluate bond strengths at the metal-ceramic interface are described. The effects of various stresses with each design are also discussed. A predictive experimental design should minimize variables and result in the least residual interfacial stresses. Dentists and dental technicians should benefit from comparisons of existing tests, and the discussion encourages introduction of more comprehensive approaches.

Button versus buttonless castings for removable partial denture frameworks.

Casting removable partial dentures (RPDs) without completely filling the sprue channels and generating casting buttons would result in saving metal and making more defect-free castings. This investigation tested whether a complete and sound RPD casting can be obtained when a minimal amount of metal is used. A factorial experimental design, three spruing methods, two metal feeding directions, and two different weights of metal were used to cast 60 Kennedy class II, modification 1 RPDs. The metal used to cast each framework was either enough to result in a full button or in no button. Visual and radiographic examinations and counting of defects were made by two independent operators who were unaware of the spruing method, feeding direction, or amount of metal used to make the framework. The completeness of the casting and the presence of porosities were evaluated for clasps, major connectors, and meshworks. The use of minimal metal to cast RPDs was equally as successful as using enough for a full button, provided that the appropriate spruing arrangement and metal feeding direction were chosen. Indirect metal feeding for maxillary RPDs was successful with the proper spruing arrangement.

A clinical trial on the effectiveness of professional toothbrushing using dentifrice and water.

The purpose of this trial was to compare the plaque removal effectiveness of professional toothbrushing with dentifrice and with only water. Fifty three subjects were divided into a dentifrice and a water group. Both groups had their teeth professionally brushed for one minute using either dentifrice or water. Plaque scores were recorded before and immediately after brushing. The results of this trial show that toothbrushing with dentifrice was more effective in removing plaque compared to brushing with water alone. The amount of plaque reduction was low, and varied with tooth surfaces. The mid buccal surface had the greatest reduction of plaque. No significant differences were observed on the distobuccal and distolingual surfaces when the dentifrice group was compared with the water group.