The effect of luting agents on the retention and marginal adaptation of the CeraOne implant system.

In this study, various luting agents were evaluated to determine their retentive strengths as they pertain to the CeraOne single-tooth implant system. Ten samples of five different luting agents (zinc oxide-eugenol, glass-ionomer cement, hybrid glass-ionomer cement, composite resin, and zinc phosphate) were tested for retentive strength of the CeraOne gold cylinder to the CeraOne abutment. Under the conditions of the experiment, zinc phosphate showed a mean retentive strength 164% greater than that of glass-ionomer cement and 49% greater than that of composite resin cement. Scanning electron micrographs were taken to evaluate the effect of various luting agents on marginal opening. The measurements revealed that zinc phosphate had the greatest marginal opening, although its mean value of 62 microns is within clinically acceptable limits.

Contouring, finishing, and polishing Class 5 restorative materials.

Three materials used for class 5 restorations (composite resin, glass ionomer, and resin-modified glass ionomer) were contoured, finished, and polished using seven methods: Matrix only, Sof-Lex disks, Composite Finishing System, Enhance Finishing/Polishing System. Two Striper MFS/MPS System. Two Striper MPS polish only, and contouring burs only. Results were quantified by surface roughness and gloss (reflectance). The glass-ionomer material was rougher and less reflective than composite resin; the smoothness and gloss of the resin-modified glass ionomer were between these two extremes. The original matrix smoothness and gloss could not be reproduced with any of the contour/finish/polish techniques tested on any of the three materials. The smoothest surfaces were achieved using a sequential series of rotary abrasive instruments.

Temporary dental restorative materials for military field use.

New temporary dental restorative materials are an important military requirement. This study compares the critical properties of the currently used temporary material, reinforced zinc oxide-eugenol (ZOE), with those of a glass ionomer restorative material (GI), a high-viscosity modified glass ionomer material (MGI), and two resin-modified glass ionomer materials (RMGIs). Properties tested included compressive and tensile strength, rigidity, hardness, bond strength, working and setting times, and storage stability. Ranked results for compressive strength, rigidity, and hardness were MGI > GI > RMGI > ZOE; for tensile strength they were RMGI > MGI > GI > ZOE; and for storage stability they were ZOE > MGI > GI > RMGI. Working and setting times were all within reasonable clinical limits, and bond strength was heavily dependent on tooth surface preparation. Although none of the materials tested met all of the ideal requirements, the high-viscosity glass ionomer material offers the most promise for military field use.

The U.S. Army Institute of Dental Research dental materials shelf-life survey: questionnaire results.

To define the nature and the extent of problems that can be related to the storage stability of perishable dental materials in the U.S. Army, questionnaires were sent to each U.S. Army Dental Corps Officer, supply NCO, and laboratory technician. Results reveal that two-thirds of dentists believe that the deterioration of perishable materials is a significant (28%) or occasional (39%) problem in their practice; the most common problem noted by dental clinicians is loss of efficacy of local anesthetics. One-half of clinicians and supply personnel report that they frequently receive perishable supplies at or near the expiration date.

The U.S. Army Institute of Dental Research dental materials shelf-life survey: lot request results.

In an attempt to determine the age of perishable dental materials used at any one time in U.S. Army dental care facilities, a questionnaire was distributed to each U.S. Army Dental Activity supply point. Results reveal that almost half of commonly used perishable dental restorative materials are older than the expiration date, determined by the manufacturer's shelf-life, at the time of use. Materials used in OCONUS facilities are generally several months older than materials within CONUS facilities. Supply personnel could not determine the shelf-life of perishable restorative dental materials from package information in over 25% of all entries.

The comparative radiopacity of Fuji IX-GP, an intermediate restorative material.

The radiopacity of intermediate restorative materials should be sufficient to enable the clinician to distinguish the material from normal and decalcified tooth structure. The purpose of this study was to determine the relative radiopacities of intermediate restorative materials, including a newly introduced high-viscosity, self-cured, condensable glass ionomer material. Radiographs were made of six intermediate restorative materials: two reinforced zinc oxide-eugenol materials (IRM and Zinroc), a conventional glass ionomer material (Ketac-fil), a synthetic resin material (Cavit), a eugenol-free zinc oxide material (Tempit), and a new, general-purpose, condensable glass ionomer material (Fuji IX-GP). Optical density was measured using a densitometer. The optical density of dentin and enamel were used for radiographic comparison. Statistical analysis revealed significant differences among materials: Cavit = IRM = Tempit > Zinroc = Fuji IX-GP > Ketac-fil = enamel > dentin (where > indicates a statistical difference at p < or = 0.05). Although not as radiopaque as some other intermediate materials tested, the radiopacity of Fuji IX-GP appears sufficient to aid diagnosis.

Resin bonding to primary teeth using three adhesive systems.

In vitro bond strengths of three resin adhesive systems were tested using 111 primary teeth. Ninety-six flat dentin surface specimens were divided into six groups consisting of 16 primed or 16 unprimed samples for each adhesive system. The remaining 15 tooth samples were divided into three groups of five to determine each adhesive system's bond strength to primary etched enamel. Resin buttons were polymerized to all specimens with visible light, thermocycled for 2000 cycles between 5 and 55 degrees C, and shear bond strength was measured with a Instron Testing Machine (Instron Engineering Corp, Canton, MA). ANOVA and multiple comparison tests showed that Optibond Multiuse Bonding Agent had a statistically greater mean shear bond strength to primary dentin (20.5 +/- 3.5 MPa) than Prisma Universal Bond 3 Multi-purpose Bonding System (9.1 +/- 4.4 MPa), Scotchbond Multi-purpose Dental Adhesive System (7.3 +/- 3.7 MPa), and primary etched enamel (9.8 +/- 4.4 MPa) at P < 0.05. This study demonstrated that resin adhesive systems may achieve bond strengths to primary dentin comparable to those of primary enamel, and that these bonds may be as strong as bonds to permanent enamel and dentin. These adhesive systems may allow more confident esthetic restoration of primary anterior teeth.

In vitro evaluation of an adhesive monomer as a bonding agent for orthodontic brackets to primary teeth and nickel-chromium ion crowns.

The adhesive monomer, Clearfil New Bond, was used to enhance the bond strength between orthodontic brackets and primary molars, premolars, and NiCr crowns. Twenty specimens of each had this dental adhesive applied according to the manufacturer's instructions in addition to a chemically cured composite material. The remaining specimens (20 each) were bonded without the adhesive monomer. Shear bond strengths were determined using a universal testing machine. Fracture sites were examined to determine the type of bond failure. All bond strengths were significantly increased with the addition of Clearfil New Bond (P < or = 0.0001). The shear bond strength to NiCr crowns with the addition of the adhesive monomer was 7.76 kg. This is comparable to the shear bond strength observed for primary molars (8.66 kg) and premolars (8.65 kg) without adhesive monomer. The observed decrease in adhesive bond failures with the addition of Clearfil New Bond indicated a stronger shear bond strength between the tooth surface and the bracket base. Clearfil New Bond can significantly increase the shear bond strength of orthodontic brackets to both primary molars and premolars. Additionally, it was shown that orthodontic brackets can be successfully bonded to Ni-Cr crowns at strengths comparable to primary or permanent enamel.

Interim dentures for the older patient who is medically compromised.

The concept of interim or transitional dentures is appropriate to the treatment of older patients who are hospitalized or medically compromised. This paper briefly reviews the emotional and physiological needs of these patients, and illustrates a case in which an interim denture technique was beneficial.

The relationship between pH and concentrations of antioxidants and vasoconstrictors in local anesthetic solutions.

pH affects the efficacy of local anesthetics by determining the percentage of the lipid-soluble base form of the anesthetic available for diffusion and penetration of the nerve sheath. The purpose of this study was to determine the relationship between pH and the concentrations of antioxidant and vasoconstrictor in dental local anesthetic solutions over real-time and after accelerated aging. Several batches of lidocaine and mepivacaine with vasoconstrictors were tested. Results showed that, immediately upon receipt from the manufacturers, three batches were below the USP pH limit (pH 3.3), and two batches contained less than the minimum limit of vasoconstrictors (90%). Real-time tests on batches that were within normal limits revealed that solutions were stable past 4 yr. Accelerated aging tests revealed a strong correlation between a decrease in pH and loss of antioxidants and vasoconstrictors. In conclusion, a quality batch of local anesthetic should remain efficacious long past the manufacturer's stated shelf life; a batch that is less than optimal, or one that is exposed to environmental stresses, will degrade rapidly, and efficacy may be affected by decreases in pH and loss of vasoconstrictor. pH may be an inexpensive, readily available screening test for efficacy of local anesthetics.

Effects of evaporation on the properties of water-based dental luting agents.

The most commonly used luting agents for fixed prosthodontics are water-based cements: zinc phosphate, zinc polycarboxylate, glass ionomer, and resin-modified glass ionomer. Properties were tested at baseline and after the cement liquids were allowed to evaporate for 10, 20, and 30 minutes. Viscosity, pH, contact angle, and surface tension were determined using the cement liquids only; tensile strength, hardness, film thickness, and working/setting times were determined after the cements had been mixed with the various liquids. pH decreased over 30 minutes, while viscosity, contact angle, and film thickness all increased, especially for the zinc polycarboxylate and glass ionomer cements. Changes in mechanical properties depended upon time and material.

The longevity of resin-based composite restorations in posterior teeth.

A survey of published prospective and retrospective studies examining the longevity of posterior resin-based composite and amalgam restorations confirms the need for clinical judgment in materials selection.

The storage stability of dental composite resins: seven-year results.

The properties of chemically cured and light-cured composite resins were recorded at baseline and at intervals over seven years, while the materials were exposed to controlled storage conditions as well as to various conditions typical of clinical situations. For chemically cured resins in clinical conditions, mechanical properties decreased, and working and setting times increased over four years; if refrigerated (controlled), properties remained constant past seven years. For light-cured resins, test results were constant over the entire seven-year test period regardless of storage conditions. An accelerated aging protocol was developed to allow for the evaluation of the relative storage stability of new and similar materials.

Microleakage under amalgam restorations lined with Copalite, Amalgambond Plus, and Vitrebond.

To evaluate the effectiveness of 3 cavity-preparation lining agents in reducing microleakage under amalgam restorations, the apices of 64 human molars were sealed with amalgam, and Class V preparations were placed. Following storage and thermocycling, the molars were placed in acid fuchsin for 24 hours, then sectioned longitudinally. Ranked data were used to score dye penetration. A Kruskal-Wallis statistical test was used to compare the three groups to the control. Teeth treated with glass ionomer cement showed a statistically significant increase (p = .0227) in dye penetration. Dye penetration increased when Amalgambond Plus and glass ionomer resin liner were placed under amalgam restorations. No difference in dye penetration was observed when Copalite was applied. Results of this study do not support routine use of these agents under amalgam restorations for control of microleakage.

Effect of sterilization on stiffness and dimensional stability of rubber-dam clamps.

Simulated clinical conditions were used to test the effect of sterilization on rubber-dam clamp stiffness and dimension. Sixty Hygienic and Ivory W7 clamps were either steam or dry heat sterilized and compared to controls. Stiffness and dimensional change between Ivory clamp groups was significant (p<.0001); the sterilized clamps showed less change than the controls. Hygienic groups showed a significant different between the control and dry heat groups (p<.05); the sterilized clamps showed less change than the controls. The change in stiffness and interjaw width for all Ivory clamps compared to all Hygienic clamps was significant (p<.0001). The Hygienic clamps changes less than the Ivory clamps. The results indicate that steam and dry heat sterilization do not affect retention of rubber-dam clamps.

A comparison of commercially available mouthguards and a custom mouthguard.

Participation in sporting events involves a risk of injury to the teeth and surrounding structures. The purpose of this study was to compare the properties of a custom mouthguard and three commercially available mouthguards. Tests included rebound upon impact as well as incisor thickness and hardness after fabrication. Results revealed that all three commercially available mouthguards exhibited greater rebound than the custom mouthguard. Rebound was related directly to the thickness of the mouthguard in the incisor region. The thickness of a mouthguard may be critical to avoiding injury to the teeth and surrounding structures.

Comparison of 10% carbamide peroxide and sodium perborate for intracoronal bleaching.

The purpose of this study was to compare 10% carbamide peroxide to the combination of sodium perborate and water as intracoronal bleaching agents. Forty-four extracted teeth were discolored in vitro. Bleaching agents were placed intracoronally to the level of the cemento-enamel junction for 12 days; solutions were replaced after four and eight days. Standardized slides were used to rank color changes; a colorimeter was used to quantify color change. After 12 days, 65% of the discolored teeth in the 10% carbamide peroxide group and 67% of the discolored teeth in the sodium perborate group had lightened to their original shade or lighter. While there was no statistical difference between the two treatments, sodium perborate was easier to use.

A review of the strength properties of dental ceramics.

New ceramic materials for restorative dentistry have been developed and introduced in recent years. This article reviews advantages and disadvantages of dental ceramics, concentrating on strength properties. Included are factors affecting the strength of dental ceramic materials and the most common mechanisms for increasing the strength of dental ceramics. The properties of presently available materials such as dispersion-strengthened ceramics, cast ceramics, and foil-reinforced materials are discussed. Current research efforts to improve the fracture resistance of ceramic restorative materials are reviewed. A description of methods to evaluate the strength of ceramics is included, as a caution concerning the interpretation of strength data reported in the literature.