Bruce J. Crispin

Dental luting agents: A review of the current literature

STATEMENT OF PROBLEM The practice of fixed prosthodontic has changed dramatically with the introduction of innovative techniques and materials. Adhesive resin systems are examples of these changes that have led to the popularity of bonded ceramics and resin-retained fixed partial dentures. Todays dentist has the choice of a water-based luting agent (zinc phosphate, zinc polycarboxylate, glass ionomer, or reinforced zinc oxide-eugenol) or a resin system with or without an adhesive. Recent formulations of glass ionomer luting agents include resin components (resin-modified glass ionomers), which are increasingly popular in clinical practice. PURPOSE This review summarizes the research on these systems with the goal of providing information that will help the reader choose the most suitable material. MATERIAL The scientific studies have been evaluated in relation to the following categories: (1) biocompatibility, (2) caries or plaque inhibition, (3) microleakage, (4) strength and other mechanical properties, (5) solubility, (6) water sorption, (7) adhesion, (8) setting stresses, (9) wear resistance, (10) color stability, (11) radiopacity, (12) film thickness or viscosity, and (13) working and setting times. In addition, guidelines on luting-agent manipulation are related to available literature and include: (1) temporary cement removal, (2) smear layer removal, (3) powder/liquid ratio, (4) mixing temperature and speed, (5) seating force and vibration, and (6) moisture control. Tables of available products and their properties are also presented together with current recommendations by the authors with a rationale.

The marginal accuracy of treatment restorations: A comparative analysis

1. Silness, J.: Periodontal considerations in patients treated with dental bridges. J Periodont Res 5:219, 1970. 2. Bergman, B., Hugoson, A., and Olsson, C.: Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. Acta Odontol Sand 29:621, 1971. 3. Karlsen, K.: Gingival reactions to restorations. Acta Odontol Sand 28:895. 1970. 4. Waerhaug, J.: Histological considerations which govern where margins of restorations should be located in relation to the gingiva. Dent Clin North Am 4~161, 1960. 5. Paloma, F., and Peden, J.: Periodontal considerations of restorative procedures. J PROSTHET DENT 36:387, 1976.

Color stability of temporary restorative materials

In this study it was shown that: 1. There was a statistically significant initial color difference in materials labeled shade 65. 2. Rough materials darkened significantly more than polished materials. 3. There was not statistically significant over all difference in the amount of staining between air-cured and pressure-cured samples. 4. The methyl methacrylates materials demonstrated that least darkening, followed closely by the ethyl-methyl methacrylate material. The vinyl-ethyl methacrylate material darkened consistently more in 14 and 30 days and significantly more at 60 days. The epimine material was consistently the least color stable and showed a significantly greater amount of darkening.

Effect of different metal ceramic alloys on the color of opaque and dentin porcelain

Certain metal ceramic alloys alter the final color of bonded porcelain. Contradicting results, inconsistent test designs, and incomplete alloy selections have led to some confusion. In this study, differential colorimetric analysis was done at the opaque and dentin porcelain stages with five major types of metal ceramic alloys. The color stability of the porcelain on the high-noble metal alloys was found to be excellent. The palladium-silver and nickel-chromium alloys resulted in significant color changes of the dentin porcelain only. The greatest changes in color were found with the palladium-silver alloy, which resulted in a higher yellow-green saturation. The nickel-chromium alloy also produced a color change, although not as severe, resulting in a porcelain shade with a reduced Value or lightness.

A longitudinal clinical study of bonded fixed partial dentures: The first 5 years

Etched-metal, composite resin-bonded, fixed partial dentures, as described in the early 1980s, gained an immediate application and popularity in restorative dentistry. This initial report presents the results of the first 5 years of a 10-year longitudinal study of these restorations. A total of 71 fixed partial dentures, ranging in use from 13 to 65 months, that were placed at the University of California, Los Angeles, School of Dentistry using consistent design parameters and restorative techniques have been analyzed. The results of this initial report indicate: (1) bonded fixed partial dentures are technique-sensitive; (2) optimal success requires meticulous attention to procedural detail; (3) anterior bonded fixed partial dentures do not appear to need routine 180-degree-plus circumferential retainer preparation for predictable success; (4) posterior bonded fixed partial dentures appear to require 180-degree-plus circumferential preparation for predictable success; (5) for single-tooth posterior replacements or single-to-double tooth anterior replacements, bonded fixed partial dentures are a viable alternative to conventional fixed partial dentures when intact abutments exist; and (6) most failures occurred within the first year.

Effect of porcelain crown substructures on visually perceivable value.

Factors that will affect the potential color of ceramic restorations must be understood to control variables that exist. Clinical observations of porcelain restorations lead to the hypothesis that certain substructures tend to produce crowns with a lower than expected Value (brightness). This study was done to determine whether a visually perceivable difference could be detected between groups of ceramic crowns with different substructures. Two test groups of crown types with four different porcelain substructures were compared. In the first group, metal ceramic crowns made with either Galaxy or Rexillium III alloys were compared. In the second group, aluminous porcelain jacket crowns with and without a tin-plated, bonded platinum foil internally were compared. Visual analysis showed that (1) in the metal ceramic group, the crowns with the Rexillium III substructure were scored as more often having a lower significant Value, and (2) in the aluminous porcelain jacket group the crowns with the tin-plated, bonded platinum substructures were scored as more often having a lower significant Value.

Relative color stability of ceramic stains subjected to glazing temperatures

Ceramic stains are routinely used to modify Hue or characterize ceramic dental restorations. Subjective opinion has led to the hypothesis that certain stains are not color stable when subjected to glazing temperatures. This study tested the individual stains in nine different ceramic staining kits for color stability when subjected to glazing temperatures. Ceramic disks were made with gingival porcelain and coated with individual stains. Colorimetric recordings were made before and after glazing and the color difference (delta E) was calculated. Significant color changes were noted for specific individual stains from each of the ceramic staining kits tested.

Margin placement of esthetic veneer crowns. Part III: Attitudes of patients and dentists

Attitudes of 396 subjects were surveyed concerning crown margin placement, and 112 dentists were surveyed regarding their treatment approach in respect to crown margin placement. The results of this study indicate that: 1. Routine subgingival margin placement of esthetic crowns may overtreat many patients. 2. Routine subgingival margin placement of esthetic crown is not always necessary. 3. Some patients may accept supragingival crown margins, even if they show. 4. A substantial group of patients may prefer optimum health potential over esthetics. 5. A thorough diagnosis should include analysis of patients attitudes.

Silver-plated dies. Part II: Marginal accuracy of cast restorations

This laboratory study simulated actual clinical crown fabrication. Crowns were finished to the point of clinical delivery with stone and silver-plated dies made from representatives of the four major groups of elastomers. A clinically acceptable technique for judging crown margin accuracy was used, and numerical scores were assessed. Scores were analyzed statistically to compare die types, materials used, and types of discrepancies. Results of this study indicate the following information about the materials tested. The marginal accuracy of crowns fabricated on the silver-plated dies is statistically as accurate as that of crowns fabricated on stone dies in all cases and significantly more accurate in some instances. Silver-plated dies fabricated from Reprosil produced more accurate crowns than all other dies tested. Acceptable crown margins were obtainable from either stone or silver-plated dies when judged by clinical criteria. Silver-plated dies can be used without compromising crown margin accuracy.

Silver-plated dies. Part I: Platability of impression materials

The purpose of this study were to determine the acceptability of silver-plated dies made from representative brands of impression material from each of the four groups of elastomers and to determine the time required for initial plating of dies. Permlastic and Impregum , each previously shown to produce consistent silver-plated dies, were used for comparison. Representatives from the condensation-reaction and addition-reaction ( polyvinylsiloxanes ) silicones groups were tested until satisfactory materials were selected. Citricon and Xantopren - Optosil were tested in the former group and President and Reprosil in the latter. Conclusions include the following: All materials were flash-plated in 10 minutes or less. Acceptable silver-plated dies were obtained from Permlastic and Impregum . Acceptable silver-plated dies were obtained from condensation-reaction silicones with Xantopren - Optosil . From the polyvinylsiloxane group, Reprosil plated more consistently than President. Both produce acceptable dies. The technique modification studied was not effective for Citricon and President. The surface quality of silver-plated dies and the consistency of plating varies with materials. Individual impression materials should be tested prior to their routine clinical use with silver-plating procedures.