Search for charged Higgs bosons in e+e- collisions at [Formula: see text].

A search is made for charged Higgs bosons predicted by Two-Higgs-Doublet extensions of the Standard Model (2HDM) using electron-positron collision data collected by the OPAL experiment at [Formula: see text], corresponding to an integrated luminosity of approximately 600 pb-1. Charged Higgs bosons are assumed to be pair-produced and to decay into [Formula: see text], τντ or AW±. No signal is observed. Model-independent limits on the charged Higgs-boson production cross section are derived by combining these results with previous searches at lower energies. Under the assumption [Formula: see text], motivated by general 2HDM type II models, excluded areas on the [Formula: see text] plane are presented and charged Higgs bosons are excluded up to a mass of 76.3 GeV at 95 % confidence level, independent of the branching ratio BR(H±â†’τντ ). A scan of the 2HDM type I model parameter space is performed and limits on the Higgs-boson masses [Formula: see text] and mA are presented for different choices of tanß.

Repair of non-carious amalgam margin defects.

This study investigated the microleakage associated with the repair of non-carious amalgam defects using flowable resin composite. Occlusal amalgam preparations were accomplished on 36 non-carious mandibular molars. A standardized 40-micron marginal defect was made by condensing amalgam against a mylar matrix strip. Specimens then underwent a corrosion protocol designed to simulate intraoral corrosion seen with amalgam restorations. The resultant specimens were divided into three treatment groups: 1) No treatment (control); 2) Air abrasion of the amalgam defect surface, acid etching of both amalgam and enamel surfaces, then placement of a flowable composite and 3) Air abrasion of the amalgam defect, application of a fifth-generation dentin bonding agent and placement of the flowable composite. Specimens were thermocycled, sealed with glass ionomer and fingernail polish to within 1 mm of repaired margins, then immersed in basic fuchsin for 24 hours. Specimens were sectioned and microleakage assessed. Results indicated that a flowable resin composite significantly reduced marginal microleakage compared to the control (p < 0.05). There was no difference in microleakage between flowable resin composite repairs done with or without the use of a dentin-bonding agent.

Stylohyoid syndrome: a case report.

Elongation of the styloid process and/or ossification of the stylohyoid ligament can be associated with cervical pharyngeal pain, which may be detected both clinically and radiographically. Eagle's syndrome, stylohyoid syndrome, and pseudostylohyoid syndrome should be considered in the differential diagnosis.

The use of resin composite pins to improve retention of Class IV resin composite restorations.

This study evaluated the effect of an intracoronal resin composite pin on Class IV resin composite restorations. A control group of 16 bovine teeth was prepared with standardized conventional Class IV preparations. For an experimental group, 16 similar Class IV preparations were made, with the addition of an intracoronal pin channel prepared with a #330 bur into the dentin. All specimens were restored with Herculite XRV and OptiBond according to the manufacturer's recommendations. After one week, specimens were placed in an Instron Universal Testing Machine and loaded at 90 degrees to the long axis until the restorations failed. Results indicated that the mean fracture load of the Class IV restoration group, with the resin composite pin, was 36% higher than the conventional Class IV group (p = 0.02). An intracoronal resin composite pin may aid the retention and resistance form of complex resin composite restorations.

Performance of high-speed dental handpieces subjected to simulated clinical use and sterilization.

BACKGROUND: The authors investigated the performance of nine commercially available high-speed air-turbine dental handpieces subjected to 1,000 simulated clinical uses and sterilizations. METHODS: Six new handpieces from each of nine different models were subjected to simulated clinical use with a custom-made handpiece wear tester and then autoclaved. Ten parameters related to clinical performance (longevity, power, turbine speed, fiberoptic transmission, eccentricity, noise, chuck performance, visibility angle, interocclusal clearance and water coolant spray pattern) were measured at baseline and after 250, 500, 750 and 1,000 use/sterilization cycles. RESULTS: Power, turbine speed, eccentricity and noise performance were statistically analyzed using one-way analysis of variance and Turkey post hoc pairwise comparison tests at the .05 significance level. At baseline, significant differences were found between models for all of these parameters. In general, from baseline to 1,000 cycles, the handpieces exhibited greater eccentricity and reduced fiberoptic performance. Longevity data analyzed by using Gehan's generalized Wilcoxon test for comparison of survival distributions (alpha = .05) revealed significant differences between the handpiece models. CONCLUSIONS: The results of this study indicate that no handpiece model is superior to the others in all parameters evaluated. All models evaluated can be expected to perform for at least 500 clinical use/sterilizations, or approximately one year, if properly maintained. CLINICAL IMPLICATIONS: Clinicians need to be able to identify handpieces that can withstand repeated heat sterilization without loss of performance or longevity. The results of this study will aid clinicians in selecting handpiece models that meet their needs.

Comparative radiopacity of flowable resin composites.

OBJECTIVE: This in vitro investigation aimed to determine the radiopacity of eight recently introduced "flowable" restorative resin composites and to compare their radiodensities to those of enamel, dentin, and a widely used composite marketed for universal application in anterior and posterior teeth. METHOD AND MATERIALS: A total of 45 composite specimens were fabricated in cylindrical molds and exposed to a curing light for 120 seconds. Two methods were used to determine radiopacity: a transmission densitometer and a computer-assisted densitometric image analysis station. RESULTS: Of the eight flowable resin composites tested, only three exhibited a radiopacity equal to or greater than that of enamel, a widely followed guideline for clinicians' diagnostic ability. The radiopacity of the remaining five materials was not statistically significantly greater than that of dentin. CONCLUSION: The level of radiopacity of the tested flowable composites was variable; those with low radiodensity should be avoided in Class II restorations, where a clear determination of recurrent caries by the examining clinician could be compromised.

Effect of curing-tip diameter on the accuracy of dental radiometers.

The purpose of this study was to determine the accuracy of four commercially available radiometers when curing tips of different diameters were used. A visible-light curing unit (Optilux 500) with a new 80-watt quartz-halogen bulb (OptiBulb) was used as the light source for all measurements. The unit's irradiance value was measured using three hand-held radiometers (Demetron model #100, Cure-Rite model #644726, and Coltolux Light Meter) and a built-in visible-light curing unit radiometer (Optilux 500). Measurements were made with four curing tips of diameters 4 mm, 7.5 mm, 10.5 mm, and 12 mm. For each tip, trials were made with five radiometers of each model. Student's t-tests at the 0.05 level of significance were used to compare the mean irradiance measured by each model of radiometer, to the irradiance value measured by a laboratory-grade power meter. A one-way analysis of variance at the 0.05 level of significance was used to compare the irradiance values among the five samples of each commercially available radiometer model. Except for the Optilux 500 built-in radiometer with the 10.5-mm tip, all the commercially available radiometers exhibited irradiance values significantly different from those of the laboratory-grade power meter. There were no statistically significant differences among the five samples of each commercially available radiometer model.

Repairability of three resin-modified glass-ionomer restorative materials.

The purpose of this study was to evaluate the repair shear bond strengths of three resin-modified glass-ionomer restorative materials repaired at two different times. Thirty specimens of Fuji II LC, Vitremer, and Photac-Fil were prepared in cavities (2 mm x 7 mm) cut into acrylic resin cylinders. After the initial fill, half of the specimens were repaired 5 minutes later and half 1 week later. The specimens were stored in 37 degrees C distilled water when not being repaired or tested. Repairs were made without any surface preparation of the initial fill. Each specimen was mixed according to the manufacturer's directions, placed in the preparation in 1-mm increments and photocured for 40 seconds. The last increment was covered with a plastic strip and a glass slide before curing to create a smooth surface. Repairs were accomplished by drying the specimen for 10 seconds, then adding the new material to the unprepared surface using a 3-mm-thick polytetrafluoroethylene mold. The specimens were thermocycled 500 times, stored in 37 degrees C distilled water for 1 week, then loaded to failure in shear at a rate of 0.5 mm/min. Data were analyzed using a one-way ANOVA and Z-value multiple comparison test to determine significant differences at the 0.05 significance level. Vitremer showed no significant difference in shear bond strength for 5-minute and 1-week repair periods, while Fuji II LC and Photac-Fil did. Repair bond strength of Vitremer was significantly greater than Fuji II LC and Photac-Fil at both repair times. This study showed that time of repair significantly affected the bond strength of two of the materials tested.

Dentin bonding: past and present.

Dentin-bonding agents have changed dramatically since being introduced. The large number of these products, as well their dynamic nature and myriad clinical uses, make it difficult for clinicians to understand how they work and when to use them. Sequential development of dentin-bonding agents from the mid-1950s to the present is described. Information also is provided about current popular bonding products and new clinical applications.

Immersion disinfection of irreversible hydrocolloid impressions in pH-adjusted sodium hypochlorite. Part 2: Effect on gypsum casts.

Lowering the pH of sodium hypochlorite has been shown to greatly improve its efficacy as a disinfectant for irreversible hydrocolloid. This study evaluated the surface roughness and detail reproduction of gypsum casts recovered from impressions disinfected with sodium hypochlorite at altered pH levels. The experimental disinfectants were sodium hypochlorite 0.525% (10-minute immersion) at pH 11.5 (unaltered), pH 10, and pH 8. An additional group was tested at pH 10 for 5 minutes. There was a trend toward increased surface roughness as the pH was lowered, but a 5-minute immersion of impressions in sodium hypochlorite at pH 10 produced casts of equivalent surface roughness to impressions rinsed in water and poured immediately. The test for surface detail reproduction produced similar results.

Effect of triturator speed variation on physical properties of encapsulated glass-ionomer luting cements.

This in vitro study evaluated the effect of variation of triturator mixing speed on the physical properties of two encapsulated glass-ionomer luting cements. Physical properties evaluated were working time, setting time, film thickness, and 24-hour and 7-day compressive strengths. Encapsulated glass-ionomer luting cements were mixed at 3000, 3500, 4000 (control), and 4500 cycles per minute (cpm). An oscillating rheometer was used to determine working and setting times. Film thickness and compressive strength were determined using methods described in ANSI/ADA Specification No 66 for dental glass-ionomer cements. Results of the study indicated that decreased mixing speed may prolong working and setting times for Ketac-Cem Maxicap and Fuji Cap I. Within the range of 3500 to 4500 cpm, variations in mixing speed do not significantly affect compressive strength or film thickness values for either cement. Excessively slow mixing speed (3000 cpm) often resulted in the presence of unmixed powder expressed from the capsule nozzle prior to the expression of mixed cement. The presence of this unmixed powder results in a decreased powder/liquid ratio, which may have an adverse effect on the physical properties of the set cement.

Repairability of polyacid-modified composite resin.

The purpose of this study was to evaluate the effect of time and surface treatment on the resulting shear bond strength of a repaired polyacid-modified composite resin restorative material (VariGlass VLC). Seventy-two specimens of VariGlass were prepared in cavities (2 mm X 7 mm) cut into acrylic resin cylinders. The specimens were then divided into three groups of 24. For each of the three groups, 12 of the specimens were repaired 5 minutes after the cavities were initially filled, while 12 specimens were repaired 1 week after the initial fill. The VariGlass surfaces were treated in one of the following ways: no treatment; primer (30 seconds) and adhesive (light activated for 10 seconds); or 37% phosphoric acid etchant (30 seconds), primer (30 seconds), and adhesive (light activated for 10 seconds). Repairs were made using a split polytetrafluoroethylene mold (3 mm X 5 mm) mounted over the exposed VariGlass surface. After bonding a cylinder of VariGlass to the treated surfaces, the specimens were thermocycled 500 times (5 degrees C and 55 degrees C water baths), stored in distilled water for 1 week, and loaded to failure in shear at 0.5 mm/min. Data were analyzed using two-way ANOVA and a Student-Newman-Keuls multiple comparison test. Results indicated that the bond strength of specimens repaired at 5 minutes was significantly higher when no surface treatment was used prior to repair. Bond strength of specimens repaired at 1 week was unaffected by surface treatment. Time of repair significantly affected the no-treatment and the primer-adhesive groups.

Effect of dentin moisture and storage time on resin bonding.

PURPOSE: To evaluate the effects of dentin moisture and two different storage times on the shear bond strength of resin composite bonded to dentin with Scotchbond Multi-Purpose Adhesive. MATERIALS AND METHODS: The occlusal surfaces of 60 extracted human molars were reduced to provide flat dentin surfaces. After being hand-finished using wet 400- and 600-grit SiC papers, the teeth were randomly divided into four groups of 15 specimens each. The teeth were etched, rinsed, and then either blotted with gauze which left a visibly moist surface or dried with compressed air. The primer and adhesive were applied according to the manufacturer's instructions and resin composite cylinders were bonded to the teeth. Two of the groups (one moist, one dry) were stored for 24 hours in 37 degrees C distilled water while the other two groups were stored for 90 days in 37 degrees C distilled water. At the end of their storage times, the specimens were loaded to failure in shear at 0.5 mm/minute. RESULTS: Mean bond strength values and standard deviations in MPa were: Dry dentin at 24 hrs, 13.30 +/- 5.1; Dry dentin at 90 days, 13.07 +/- 3.8; Moist dentin at 24 hours, 13.64 +/- 4.9; Moist dentin at 90 days, 15.58 +/- 5.3. No statistically significant differences were found for bond strengths to dry and to moist dentin for either storage time. Time had no significant effect for either the dry dentin group or the moist dentin group.

Dentin treatment with an oxalate solution and glass ionomer bond strength.

PURPOSE: To evaluate the effect of dentin surface treatment on shear bond strengths of two visible light-cured glass ionomer restorative materials to dentin. MATERIALS AND METHODS: Cylinders of Fuji II LC and VariGlass VLC were bonded to dentin surfaces that were (1) treated as directed by the manufacturer, (2) treated with a monohydrogen-monopotassium oxalate solution (Protect Dentin Desensitizer), or (3) treated with the monohydrogen-monopotassium oxalate solution followed by treatment per the manufacturer. Specimens were thermocycled and tested in shear at 7 days. Data for each restorative material were subjected to a one-way ANOVA and the Scheffé F-test (P < 0.05). After shear bond testing the specimens were examined using a stereomicroscope at x8 to determine the mode of failure (adhesive, cohesive or mixed). Dentin specimens were also surface treated as described above, sputter-coated, and examined using a scanning electron microscope. RESULTS: In every instance, the oxalate solution significantly reduced the shear bond strength of both materials.

Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part II: Effect on gypsum.

This study investigated the effects of various immersion times and concentrations of sodium hypochlorite on irreversible hydrocolloid impressions and resultant gypsum casts. Irreversible hydrocolloid impressions of a test die were immersed for 1, 5, or 10 minutes in water (control), 5.25%, 0.525%, and 0.0525% sodium hypochlorite and then cast in a Type III stone and a Type V stone. Each stone specimen was evaluated for detail reproduction, dimensional change, surface roughness, and surface hardness. The results indicated that impressions may be immersed in sodium hypochlorite for any of the experimental times and concentrations without negative effects on Type V stone casts. However, immersion of impressions in 5.25% sodium hypochlorite causes some surface deterioration on Type III stone casts.

The effect of dentin surface moisture on bond strength to dentin bonding agents.

This in vitro study compares the mean shear bond strengths of two dentin bonding agents to dry and to moist human dentin. The occlusal surfaces of 60 extracted human molars were ground to produce flat dentin surfaces. The teeth were divided into four groups of 15 specimens each. For Scotchbond Multi-Purpose dentin bonding agent, the teeth were etched, rinsed, and then either blotted with gauze, which left the dentin moist, or dried with compressed air. The primer and adhesive were then applied, and composite cylinders were bonded to the teeth. For Optibond, the teeth were again either blotted with gauze or dried with air. The primer and dual-activated adhesive were applied, and composite cylinders were bonded to the teeth. After storage in room-temperature distilled water for 48 hours, the specimens were thermocycled. Shear bond strength testing was performed at 1 week. Analysis using two-sample t-tests found no significant difference for either product in bond strengths to moist and to dry dentin (P > 0.05). This study indicated that for some current-generation dentin bonding agents, the presence of moisture on dentin surfaces does not compromise short-term bond strength.

Dentin surface treatment and bond strength of glass ionomers.

This study evaluated the effect of dentin surface treatment on shear bond strengths of two light- cured glass ionomer restorative materials to dentin. Cylinders of Fuji II LC and VariGlass VLC were bonded to dentin surfaces that were untreated, treated with a 10% polyacrylic acid (GC Conditioner), or treated with a dentin bonding agent primer (Prisma Universal Bond 3 Primer). Specimens were thermocycled and tested in shear at 7 days. Data for each restorative material were subjected to one way ANOVA and Tukey's procedure at the 0.05 probability level. For Fuji II LC, mean bond strength to conditioner-treated dentin was significantly higher than mean bond strength to primer-treated dentin and to untreated dentin. For VariGlass VLC, mean bond strength to primer-treated dentin was significantly higher than mean bond strength to untreated dentin. Bond strengths to primer-treated dentin and conditioner-treated dentin were not significantly different.

Carbamide peroxide bleaching: effects on enamel surface hardness and bonding.

Three 10% carbamide peroxide home bleaching agents were evaluated to determine their effects on tensile bond strength of resin to enamel and enamel surface hardness. Eighty extracted bicuspid crowns were divided into four groups (three bleaching agents and control), and treated with the bleaching agents for five consecutive days. A bonding site on the buccal surface of each crown was etched with phosphoric acid and an orthodontic bracket bonded in place. The specimens were thermocycled and loaded to failure in an Instron Universal Testing Machine. Five hardness specimens per group were measured prebleaching and after five days' exposure. Analysis by one-way ANOVA indicated no significant differences in bond strength between the four groups (P > 0.05). There were also no differences in pre- or postbleaching Knoop hardness values for the four groups (P > 0.05). This study indicated that in short-term regimens 10% carbamide peroxide does not significantly affect enamel surface hardness or bonding ability.

In vitro evaluation of the use of resin liners to reduce microleakage and improve retention of amalgam restorations.

This in vitro study evaluated the ability of three commercially available adhesive resins to reduce microleakage and provide retention between amalgam restorations and tooth structure. Results indicated that Amalgambond reduced leakage significantly more than Panavia EX, Prisma Universal Bond 2, and Copalite. In addition Amalgambond and Panavia EX exhibited the ability to bond amalgam to tooth structure. These results suggest that Amalgambond has the potential for serving successfully as a cavity liner with amalgam.