Martin F. Land

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.

Survival Rates of All-Ceramic Systems Differ by Clinical Indication and Fabrication Method

SELECTION CRITERIA Approximately 50 articles were included in this review based on a MEDLINE and PubMed search of English-language peer-reviewed literature focused on research published between 1993 and 2008. The authors also hand searched relevant dental journals. Randomized controlled trials, nonrandomized controlled trials, longitudinal experimental clinical studies, longitudinal prospective studies, and longitudinal retrospective studies were all eligible for inclusion in this review. KEY STUDY FACTOR Treatment of teeth with an all-ceramic restoration in the form of a veneer, inlay, onlay, crown, or fixed dental prosthesis, and the subsequent clinical success or failure of these restorations. MAIN OUTCOME MEASURE Restoration survival rate (in percent) as a function of observation period and fabrication method, reported by restoration type. Specific fabrication methods for single-tooth restorations included InCeram Alumina, InCeram Spinell, Procera, IPS Empress, IPS Empress 2, and Dicor crowns. Fabrication methods for fixed partial dentures included InCeram, InCeram Zr, IPS Empress 2, and Cercon Zr, respectively. The reported Kaplan-Meier survival rates were grouped by restoration type rather than by ceramic system. MAIN RESULTS For porcelain veneers, less than 5% failure was reported at 5 years and less than 10% failure rate at 10 years (n ranging from 83 to 3047). For ceramic inlay and onlay restorations, 10-year failure rates were found to be less than 10% (n ranging from 200 to 1588). Greater success rates were reported for anterior crowns. Kaplan-Meier survival rates were calculated for end points ranging in duration from 1 to 4 years (6 studies), 5 to 6 years (12 studies), 7 to 8 years (5 studies), and 10 years or more (2 studies). The results for multiunit prostheses included 11 studies, fewer prostheses, and generally higher failure rates. As with single crowns, failure rates for multiunit prostheses were reported to be consistently higher in the posterior region than anteriorly. Kaplan-Meier survival rates were reported for 3-unit fixed partial dentures for end points ranging from 1 to 10 years, with a mean end point of approximately 5.6 years. CONCLUSIONS The authors suggest that many all-ceramic restorations were found to demonstrate acceptable longevity compared with conventional restorations (eg, metal-ceramic crowns). For single-rooted anterior teeth, broad support was found for the premise that clinicians may select from any all-ceramic system for laminate veneers, intracoronal restorations such as inlays and onlays, and for full-coverage restorations. For restoration of molar teeth, the review suggests that relatively few all-ceramic systems will provide predictable long-term success. The number of clinical complications with all-ceramic fixed dental prostheses (multiunit) remains high, even with increased connector size. Although zirconium systems offer the advantage of favorable material characteristics for substructures, the clinical problem of chipping of the weaker esthetic veneer persists.

Considerations for ceramic inlays in posterior teeth: a review

This review of ceramic inlays in posterior teeth includes a review of the history of ceramic restorations, followed by common indications and contraindications for their use. A discussion on the potential for tooth wear is followed by a review of recommended preparation design considerations, fabrication methods, and material choices. Despite the improved materials available for fabrication of porcelain inlays, fracture remains a primary mode of inlay failure. Therefore, a brief discussion on strengthening methods for ceramics is included. The review concludes with a section on luting considerations, and offers the clinician specific recommendations for luting procedures. In conclusion, inlay success rates and longevity, as reported in the literature, are summarized.

Smear layer instability caused by hemostatic agents

The effect of hemostatic agents, other than a 15.5% Fe2(SO4)3 solution, on prepared tooth structure is unknown. The purpose of this study was to (1) compare the effect of six commonly used hemostatic solutions and two nondental astringents on the dentinal smear layer and (2) determine whether different responses caused by product and/or time could be established. Standardized dentinal smear layers were exposed to eight astringent solutions for 30, 120, and 300 seconds (n = 6). A total of 144 SEM photographs at x2400 magnification were ranked according to predetermined criteria for five categories of smear layer removal and etching of underlying tooth structure. There were significant differences (p < 0.001) caused by the solution, exposure time, and their interaction. Greatest smear layer removal was observed with 21.3% AlCl3-6 hydrate, 8% racemic epinephrine HCl, and 15.5% Fe2(SO4)3 solutions at longer exposures. These caused significantly more removal than did almost pH neutral tetrahydrozoline or oxymetazoline (p < 0.05).

Effect of two types of latex gloves and surfactants on polymerization inhibition of three polyvinylsiloxane impression materials.

STATEMENT OF PROBLEM Polymerization inhibition of polyvinylsiloxane impression materials has been reported when in sustained contact with some types of latex gloves. PURPOSE This study examined the polymerization inhibition of 3 polyvinylsiloxane impression materials placed in contact with surfaces subjected to prior contact with gloves or commonly used surfactants. MATERIAL AND METHODS A 2 x 3 x 4 x 2 design was used (n = 20), with 2 types of gloves (powdered and unpowdered), 3 types of polyvinylsiloxane impression materials (Aquasil, Extrude, and Affinis), 4 surfactant conditions (water, soap/water-rinse, alcohol, and unexposed), and 2 ambient temperatures of 22 degrees C and 36 degrees C. After glove exposure to surfactants, a glass surface was subjected to rubbing contact with the treated glove for a standardized time. After drying, automixed polyvinylsiloxane impression materials were dispensed onto the treated surface. Specimens were removed and evaluated for polymerization inhibition at the manufacturers recommended polymerization time (36 degrees C), or after 15 minutes at 22 degrees C. Specimens were rated as polymerized, or as inhibited if any polyvinylsiloxane residue remained on the slab. A chi-square analysis was used to evaluate the results (alpha=.05). RESULTS Setting inhibition was found only with one of the polyvinylsiloxane materials when alcohol was used as a surfactant. At 22 degrees C, the inhibition rate ranged from 95% to 100% for both glove types; at 36 degrees C inhibition ranged from 40% (unpowdered gloves) to 75% (powdered gloves), respectively. CONCLUSION Under these in vitro conditions, glove exposure to alcohol resulted in polymerization inhibition of 1 of 3 tested polyvinylsiloxane impression materials (Extrude).

Retrofitting a crown to a sleep apnea device by using computer-aided design and computer-aided milling technology

Retrofitting a new crown to an existing dental device is challenging. The continued evolution of computer-aided design and computer-aided manufacturing (CAD/CAM) significantly simplifies the process. This article demonstrates retrofitting a gold crown to an existing sleep apnea device.