Zafrulla Khan

Adhesion characteristics of visible light-cured denture base material bonded to resilient lining materials

This investigation compared the adhesion of resilient lining materials to Triad visible light-cured denture base material. The liners used were Tru-Soft, Molloplast-B, and Esscheem. Cylindrical samples were made from Triad VLC material and were sectioned to produce a flat bonding surface, which was roughened and treated with Triad bonding agent. Resilient liners 3 mm thick were processed according to the manufacturers recommendations and samples were stored at 37 degrees +/- 1 degree C in distilled water for 48 hours and 30 days. Tensile bond strength was determined by using an Instron Universal testing machine for the three resilient liners.

The physical properties of a visible light-cured temporary fixed partial denture material

T he fit and function of a permanent cast restoration is often determined by the temporary coverage provided while the cast restoration is being made. The temporary crown should isolate the prepared tooth or teeth from the oral environment, stabilize the occluding and adjacent teeth, and provide compatible function, form, and esthetics. A satisfactory temporary restoration can be made from autopolymerizing acrylic resin. However, the placement of unpolymerized acrylic resins on dentin and the gingivae may lead to thermal irritation from the exothermic polymerization reaction to the resin or chemical irritation from free or residual monomer.‘,’ To combine reduced tissue toxicity and thermal irritation of the alternative resin systems with the ease of processing acrylic resins, a new visible light-cured (VLC) crown and fixed partial denture system that contains no methyl methacrylate has been introduced. This provisional fixed partial denture resin (Triad, Dentsply, York, Pa.) is ready to use from the package and remains workable until placed and cured by irradiation with visible light. Fig. 1. Rectangular specimen used in testing procedures.

Palatal shape and the flexural strength of maxillary denture bases

F racture of acrylic resin denture bases is a continuing problem in prosthodontics, which is characterized in maxillary bases by midline fractures. A recent analysis of denture base fractures indicated that the ratio of maxillary to mandibular fractures was generally 2/l based on repairs performed by commercial dental laboratories.’ In most instances, fracture could be ascribed to unsatisfactory occlusion and/or poor fit of the prostheses, although accidental trauma was also a frequent cause of fracture. In the absence of accidental trauma, fracture of dentures that fit well and occlude properly should not be a problem; however, it is known to occur because of other factors. Previous studies have indicated that deformation of denture bases occurs under masticatory loads, and the number of flexions is estimated at close to 500,000 per year.2 Over several years, the base will thus experience several million flexions during use.3 Maxillary denture bases will deform away from the palatal tissues,4 therefore, fatigue might be a significant factor ‘in fracture. However, fatigue is determined by both the number of cycles imposed as well as the shape of the structure that undergoes cyclic loading. It was decided to determine whether the shape of the underlying palate combined with the thickness of the denture base would affect the strength of the base. Inherently stronger bases are presumably more resistant to fracture because of greater flexural strength and decreased deflection under loading.

One-appointment construction of an immediate transitional complete denture using visible light-cured resin

A technique is described for construction of an immediate transitional complete denture in one appointment using self-curing tooth color and visible light-cured resins. Conventional immediate denture therapy may be too prolonged for medically or physically compromised patients. This alternative treatment reduces laboratory, dentist, and patient time, thereby providing a fast and economical service.

The bond strength of a visible light-cured reline resin to acrylic resin denture base material

The introduction of Triad visible light-cured denture resin has led to several applications. Among them is direct intraoral relining of complete and partial dentures. This study investigated the bonding characteristics of Triad reline resin to four commonly used heat-cured denture base resins. The shear and tensile bond strengths of Triad resin and four denture base resins were determined and compared with intact tensile strengths. The findings of this study indicate that the bond strength of Triad resin to denture base resin is sufficiently high to suggest its clinical applicability.

Wear of nonanatomic (monoplane) acrylic resin denture teeth

A crylic resin teeth are widely used in complete and removable partial dentures, and over the years the functional and esthetic characteristics of denture teeth have been improved. They do, however, undergo wear/abrasion in use; and although there is a standard specification for acrylic resin teeth,’ the problem of wear and abrasion is not addressed. The factors involved in wear include the pressure between the abrading surfaces, the relative speed of movement between the surfaces, the characteristics of the surfaces, and the composition of the materials in contact. Tooth wear in vivo is related to the chewing pattern of the patient, the masticatory forces exerted, the daily period of use, the dietary habits, and various other factors.2-4 Wear and abrasion studies have been made typically on denture teeth with reciprocating wear devices.4 Investigators tend to relate wear resistance to surface hardness, and a wide variety of hardness tests are used to assess surface characteristics.5s 6 In this study, the use of a commercially available abrasion test device to evaluate the wear characteristics of three brands of monoplane teeth is reported.

Soft palate obturator prosthesis made with visible light-cured resin

A technique is described using a visible light-cured resin system for the fabrication of a soft palate obturator prosthesis. This method is easy to use and saves time for both the patient and maxillofacial prosthodontist by eliminating some laboratory procedures.

Shoulder preparations for collarless metal ceramic crowns: Hand-planing as opposed to rotary instrumentation

This study was undertaken to determine whether hand-planning the gingival facial floor improved the overall fit and marginal adaptation of a collarless metal ceramic crown. An extracted central incisor was prepared conventionally. Separate impressions were made of the tooth with custom trays and poured in stone. Crowns were constructed and cemented with silicone impression material as the luting agent. The silicone film was captured in stone and sectioned. Film thickness was measured at six points on the buccal and lingual surfaces. The tooth was then modified at the gingival floor by hand-planning the margin to a smooth, flat finish, and the above procedures repeated. It was found that the fit of crowns as measured by the cement film thickness was significantly better (p less than 0.05) at the facial margin, facial, lingual incisal, and lingual surfaces for the hand-planned margins.

Effect on surface detail of casts when irreversible hydrocolloid was wetted before impression making

I rreversible hydrocolloid (alginate) impression material has been proved to be accurate in controlled studies.‘s2 A series of exacting procedures are necessary to obtain an accurate impression when this material is used. Therefore, it is important to follow the manufacturer’s directions. Some manufacturers recommend that after the impression tray is loaded, the surface of the irreversible hydrocolloid be smoothed with a wet finger before the impression is made. This investigation was designed to compare the surface accuracy of casts made when irreversible hydrocolloid was and was not smoothed before the impression was made.

Oral commissure expansion prosthesis

An expansion prosthesis to stretch commissures and fibrotic muscles is often essential for patients recovering from head and neck trauma or burns. The prosthesis is easily made in one appointment using Triad resin and a 7 mm expansion screw. Depending on the frequency of use, varying degrees of opening of the jaws can be obtained. The prosthesis is inexpensive to make and can easily be modified as needed. It is convenient for use because the patient controls the pressure that is applied by the prosthesis.