Van B. Haywood

Polishing porcelain veneers: an SEM and specular reflectance analysis.

Abstract Techniques for placement of etched porcelain laminate veneers require that the glazed porcelain veneer be cemented prior to finishing and polishing. Finishing the veneer margins corrects the inherent marginal defects but results in removal of the glaze from the porcelain. This invites a poor tissue response unless the porcelain can be polished to a smooth surface. Using scanning electron microscopy (SEM) and specular reflectance, the surface texture of autoglazed porcelain was compared with that of polished porcelain. Emphasis was placed on those instruments which are suitable for gingival and interproximal finishing. Finishing with a fine diamond instrument followed only by diamond polishing paste produced an unacceptable surface. A finish equal or superior in smoothness to glazed porcelain was achieved through the use of a series of finishing grit diamonds (Micron Finishing System) followed by a 30-fluted carbide bur and diamond polishing paste. Other finishing combinations produced surface textures which were not as smooth as glazed porcelain, but which were better than that attained by the diamond polishing paste alone.

Effects of water, speed, and experimental instrumentation on finishing and polishing porcelain intra-orally

Previous studies indicated that porcelain can be polished smoother than glazed porcelain with instruments suitable for intra-oral use. This study evaluated several experimental instruments and materials to determine if polishing could be done more efficiently. Scanning electron microscopy was used to evaluate the surface texture produced by different combinations of experimental instruments applied with high and moderate speed, wet and dry, to porcelain disks. No sequence matched the polished standard. However, the optimum surface texture was obtained with diamond instruments (with progressively smaller particle sizes) used at a moderate speed with water, followed by a 30-fluted carbide bur at high speed and dry, then diamond polishing paste on a webbed rubber cup. In all polishing sequences tested, the best results were obtained with each individual instrument when diamond instruments were used at moderate speed wet, and when carbide instruments were used at high speed dry.

Bonding agent strengths with processed composite resin veneers

Abstract Intracoronal veneers of laboratory processed composite resin are currently being employed to produce esthetic restorations that do not involve the bulk or in situ polymerization problems of more traditional veneering systems. The retention of these materials depends on the bonds formed at the veneer/bonding agent interface and the bonding agent/enamel interface. The bond strength of the veneer/bonding agent interface was investigated using resin bonding agents differing in means of polymerization, filler content, and apparent viscosity. The bond strengths were better with materials that were light-cured and less highly filled.

Thermal removal of composite resin: Effect on rebonding etched metal

If a correctly etched-metal, resin-bonded fixed partial denture debonds, one recommendation for reuse is to clean the prosthesis by oven burnout, then to recement it without reetching. The purpose of this study was to determine whether the tensile strength of the bond of composite resin cement to either electrolytically or chemically etched metal was affected by earlier removal of residual resin with a burnout procedure. Pairs of rods made of nickel-chromium-beryllium were electrolytically or chemically etched according to accepted techniques, then bonded end-to-end with an enamel bonding agent and composite resin cement in an alignment apparatus. The rods were stored for 24 hours in 37 degrees C water, then debonded to determine the tensile bond strengths in megapascals. After debonding, the rods were placed in the burnout oven at 510 degrees C for 30 minutes. The rods were then ultrasonically cleaned in ethyl alcohol for 6 minutes. The pairs were rinsed under running water and then rebonded and debonded nine more times under the same conditions. A linear regression analysis revealed that there was no statistically significant difference (p less than 0.05) in the tensile strength of the bonds after repeated thermal cleanings and bondings. Correctly etched metal, resin-bonded fixed partial dentures may be recemented without re-etching after thermal cleaning without a statistically significant loss in the tensile strength of the bonds.

Method for immediate fabrication of an occlusal device

This article describes a method of in-office fabrication of an occlusal device for treatment of bruxism patients seeking a less costly alternative to laboratory-processed splints. This technique eliminates the need for mounted casts and the expense and delay associated with commercial laboratory involvement. It also minimizes patient and operator exposure to acrylic resin monomer and high temperatures associated with its polymerization reaction by use of a light-polymerized blue urethane dimethacrylate resin.

Articulation of posterior quadrant impressions for cast restorations

The described procedure provides the dentist with a simple articulation method to reduce chair time and consumption of materials while maintaining accuracy and reliability. This uncomplicated technique should be used only when occlusal equilibration is not necessary, when there are vertical stops after tooth preparation, and when the tooth to be prepared is not involved in lateral excursions.

Custom shade tabs for esthetic provisional restorations

A technique for fabrication of custom shade tabs in tooth form has been presented. The finished product will be a series of custom shade tabs. Any temporary (provisional) resin material can be used.

Effect of Short‐Duration, Localized Carbamide Peroxide Application to Remove Enamel Staining on Bond Strength of Resin Cement to Enamel

UNLABELLED Objective Peripheral enamel staining is often noticed after removal of long-term veneer or crown provisional restorations. Application of carbamide peroxide (CP) easily removes the stain, but the potential for immediate bonding with a resin-based cement is questionable. This project tested the short-term, shear bond strength of a commercial, photo-curable, resin cement to bovine enamel after application of a 10% concentration of CP placed for different exposure times. MATERIALS AND METHODS Bovine enamel was flattened and polished. Surfaces had either no CP application (control), or 10% CP applied for 10, 20, or 30 seconds. Teeth were acid-etched, rinsed, dried, and controlled sized stubs of a commercial resin cement were photocured onto the treated surfaces. The shear bond strength of each specimen was determined using a universal testing machine, and results were compared using an analysis of variance at a preset alpha of 0.5 (n = 10/group). RESULTS No significant differences (p = 0.819) in shear bond strength were found among any CP cleaning treatments or the experimental (nontreated) control. CONCLUSIONS Short-term application of 10% carbamide peroxide prior to acid etching, to remove enamel stains in teeth prepared to receive ceramic veneers or crowns, does not reduce immediate shear bond strength of resin-based cement to enamel. CLINICAL SIGNIFICANCE Clinicians can confidently apply 10% CP for short-term, localized stain removal on enamel and not be concerned about affecting subsequent bond strength of a resin-based cement to enamel. (J Esthet Restor Dent, 2016).

A single-appointment technique for reuse of a crown after tooth fracture

A single-appointment technique for the reuse of an existing crown, the margins of which are intact after tooth fracture, has been presented. Composite resin used in conjunction with a dentin bonding agent serves as a core and cement sealer. Para Posts or TMS pins and undercut areas in tooth structure are used for retention.