Packable composites.
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Chemical Phenomena↗
Biomedical subjects
T J Hilton
Publications and source records attributed to T J Hilton.
Properties of packable dental composites.
The introduction of many new packable composites suggests that these products are rapidly gaining popularity. The purpose of this study was to evaluate the in vitro properties of a variety of packable composites and to determine if significant enhancements in physical and mechanical properties have been achieved for these materials compared with two popular nonpackable posterior composites. For the five packable and two regular composites tested (ALERT, Pyramid-Dentin, Pyramid-Enamel, Solitaire, SureFil, Heliomolar, and Z100), the values for fracture toughness, flexure strength, flexure modulus, hardness, and volumetric polymerization shrinkage were determined. In general, although the packable composites were of heavier consistency, they had mechanical properties that were intermediate to (ALERT, Pyramid, and SureFil) or lower than (Solitaire) those of the nonpackable materials. These results could have been predicted based on the similar methacrylate resin chemistry and filler volumes of the various composites. No composite had adequate depth-of-cure when tested in increments greater than 2 mm thick. Polymerization contraction of the packable composites was similar to or higher than that of the nonpackable composites. In addition, the radiopacity of at least one material, Solitaire, was not considered to be adequate (less than 2 mm of aluminum). The results of this study suggest that these packable composites are unlikely to offer improved clinical performance over well-placed nonpackable composites.
Acrylic Resins↗
Cavity preparation factors and microleakage of Class II composite restorations filled at intraoral temperatures.
PURPOSE: To determine if alteration of any of the following factors could reduce microleakage following placement of Class II resin-based composites (RBC) at intraoral temperature: cavity preparation (vertical wall bevels), finishing technique (delayed vs. immediate), or postoperative re-bonding (marginal sealing). An additional purpose was to determine if a decalcification/clearing protocol was a valid technique for assessing three-dimensional microleakage. MATERIALS AND METHODS: Twenty recently extracted human molars had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on dentin. The teeth were imbedded in a stone template, warmed to 37 degrees C and restored immediately upon removal from the oven with visible light-cured (VLC) adhesive (All-Bond 2) and three horizontal increments of VLC RBC (Bisfil P) using a metal matrix. Teeth were placed into one of four groups: (1) Control; (2) The preparation was modified to include 0.5-1.0 mm enamel bevels on the vertical walls (facial and lingual); (3) Finishing of the RBC was delayed 24 hours; (4) Following immediate finishing, all margins of the RBC restorations were sealed by dentin bonding agent application. Teeth were stored at 37 degrees C for 2 weeks, thermocycled 1000x at 5/55 degrees C, stained with silver nitrate, underwent a decalcification and clearing protocol, and evaluated for three-dimensional dye penetration. RESULTS: Axial-occlusal enamel margins exhibited minimal leakage and no differences among the groups. Vertical walls without bevels exhibited pronounced microleakage. Beveled vertical proximal walls exhibited significantly less facial and lingual wall microleakage compared to all other groups, and less gingival marginal leakage compared to the control group.
Acid Etching, Dental↗
Perioperative use of 0.12% chlorhexidine gluconate for the prevention of alveolar osteitis: efficacy and risk factor analysis.
OBJECTIVES: The purposes of this study were to evaluate the use of 0.12% chlorhexidine gluconate as a prophylactic therapy for the prevention of alveolar osteitis and to further examine subject-based risk factors associated with alveolar osteitis. STUDY DESIGN: The trial was a randomized, double-blind, placebo-controlled, parallel-group study conducted among 279 subjects, each of whom required oral surgery for the removal of a minimum of one impacted mandibular third molar. Subjects were instructed to rinse twice daily with 15 ml of chlorhexidine or placebo mouthrinse for 30 seconds for 1 week before and 1 week after the surgical extractions. This regimen included a supervised presurgical rinse. Alveolar osteitis diagnosis was based on the subjective finding of increasing postoperative pain at the surgical site that was not relieved with mild analgesics, supported by clinical evidence of one or more of the following: loss of blood clot, necrosis of blood clot, and exposed alveolar bone. RESULTS: In comparison with use of the placebo mouthrinse, prophylactic use of the chlorhexidine mouthrinse resulted in statistically significant (p < 0.05) reductions in the incidence of alveolar osteitis. With chlorhexidine therapy, the subject- and extraction-based incidences of alveolar osteitis in the evaluable subset (271 subjects) were reduced, relative to placebo, by 38% and 44%, respectively. The corresponding odds ratios that describe the increased odds of experiencing alveolar osteitis in the placebo group were 1.87 and 2.05 for subject- and extraction-based analyses, respectively. In comparison with nonuse of oral contraceptives, the use of oral contraceptives in female subjects was related to a statistically significant increase in the incidence of alveolar osteitis (odds ratio = 1.92, p = 0.035). Relative to male subjects, the observed incidence of alveolar osteitis for female subjects not using oral contraceptives was not statistically significant (odds ratio = 1.18, p = 0.64). Smoking did not increase the incidence of alveolar osteitis relative to not smoking (odds ratio = 1.20, p = 0.33). CONCLUSIONS: These data confirm that the prophylactic use of 0.12% chlorhexidine gluconate mouthrinse results in a significant reduction in the incidence of alveolar osteitis after the extraction of impacted mandibular third molars. In addition, oral contraceptive use in females was confirmed to be a risk factor for the development of alveolar osteitis.
Adolescent↗
Microleakage of four Class II resin composite insertion techniques at intraoral temperature.
Twenty recently extracted human molars had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on dentin. The teeth were embedded in a stone template, warmed to 37 degrees C, and restored immediately using one of two incremental placement techniques with visible light-cured composite (VLC), or one of two directed shrinkage placement techniques using an autocure/VLC composite combination. Teeth were stored at 37 degrees C for 2 weeks, thermocycled, stained, sectioned in the middle of the preparation, and evaluated for dye penetration. Reevaluation of the microleakage following removal of the resin composite from the preparation revealed greater microleakage at the gingival margin than did the initial sectioning technique. There were no differences among any of the groups. Enamel margins exhibited minimal leakage and no differences among the groups.
Composite Resins↗
Effect of thermocycling on the microleakage of conventional and resin-modified glass ionomers.
PURPOSE: To compare the effect of thermocycling on the microleakage of conventional and resin modified glass ionomer restorative materials. MATERIALS AND METHODS: Class V preparations, centered on the CEJ, were prepared on the lingual and facial surfaces of 30 extracted human third molar teeth. Preparations were conditioned and restored randomly on one surface with Ketac-Fil and on the other surface with Photac-Fil. Restorations were protected during curing, finishing, and storage with Ketac-Glaze. Specimens were aged in room temperature distilled water for 7 days. Half of the specimens were thermocycled for 2,500 cycles in 5 degrees-55 degrees water baths with 5-second dwell times. All specimen apices were sealed with red compound, occlusal fissures sealed with pit/fissure sealant, and surfaces painted to within 1.5 mm of restoration margins with red nail polish. Specimens were stained with 5% methylene blue, invested in orthodontic resin, and sectioned faciolingually. The percentage of dye penetration along the tooth restoration interface was measured with a digital imaging system. RESULTS: Statistical analysis showed that neither thermocycling or type of material had a significant effect on dye penetration (P > 0.5).
Analysis of Variance↗
Retention of complex amalgam restorations using self-threading pins, amalgapins, and Amalgambond.
PURPOSE: To compare the shear fracture resistance of complex amalgam restorations retained by four regular TMS pins, four amalgapins, Amalgambond, or four amalgapins in conjunction with Amalgambond. MATERIALS AND METHODS: Sixty maxillary molars free of caries were mounted in acrylic resin and the occlusal surfaces were ground flat to within 2 mm of the CEJ. The specimens were randomly divided into four groups of 15 teeth. Each group provided one of the four different methods of resistance. Dispersalloy was condensed into the prepared specimens. The specimens were adjusted to provide 4 mm height of amalgam. After 1000 thermocycles, the specimens were loaded at a 45 degree angle to the occlusal surface at a crosshead speed of 1 mm/second. RESULTS: Statistical analysis revealed that Amalgambond, four amalgapins and four amalgapins in conjunction with Amalgambond provided more resistance to shear force than four regular TMS pins.
Analysis of Variance↗
A comparison of bond strengths among chairside hard reline materials.
Several chairside hard resin reline materials have been introduced to improve the fit and function of existing denture bases. However, it is not known whether the bond strengths among the various chairside reline and denture base materials are significantly affected by their differences in chemical composition. This study evaluated the bond strengths of five chairside hard reline materials (Extoral VLC, Flexacryl Hard, Kooliner, Light Liner, and Triad Hi-Flow VLC reline material) to two different denture base resins (Lucitone 199 and Triad VLC) by use of a three-point transverse flexural test. The reline resins are representative of autopolymerizing, light- and dual-cured materials. The results indicate that Triad VLC reline resin with bonding agent gave the highest bond strengths to Triad VLC denture base resin. Light Liner reline resin gave the highest repair bond strengths to Lucitone 199 denture base resin.
Acrylic Resins↗
Fracture resistance of complex amalgam restorations with peripheral shelves used as resistance features.
This in vitro study compared various peripheral shelves (steps) as resistance features for complex amalgam restorations. Three different sizes of peripheral shelves were evaluated: 1 mm x 1 mm, 2 mm x 2 mm, and 1 mm cervically x 2 mm pulpally. The resistance of these features was compared to a control group that utilized two amalgam pins. The 1 mm x 1 mm shelf provided significantly less resistance than the other groups.
Analysis of Variance↗
Effect of temporary cements on the bond strength of a resin cement.
This study evaluated the effect of temporary cements with or without eugenol on the bond strength of a dual-cure resin cement to dentin. Etched, silanated Dicor buttons were bonded to dentin surfaces after pretreatment with the cements. The buttons were sheared in an Instron testing machine. The results showed that shear bond strength is not affected by the temporary cements, if the dentin is cleaned with pumice and treated with Prisma Universal Bond 3 dentin bonding system.
Analysis of Variance↗
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.
Analysis of Variance↗
Evaluation of different methods for cleaning and preparing occlusal fissures.
The effectiveness of different methods for cleaning and preparing occlusal fissures before placing sealants was evaluated. Extracted mandibular molars received such treatments as brushing, pumicing, bur preparing, and air abrasion before application of fissure sealants. FluroShield fissure sealant was then applied to the occlusal fissures. Specimens were subjected to thermo-cycling and then immersed in a 10% solution of methylene blue, and finally sectioned. The sections were examined and photographed in a stereomicroscope, and the dye penetration was recorded using a scoring system. The results indicated that only the control (brushing with a dry brush) and the pumicing groups demonstrated dye penetration to the base of the sealant. Teeth prepared with the #1/4 round bur and air abrasion demonstrated a better seal in evaluated fissures. For this study, those three groups (occlusal fissures prepared with the #1/4 round bur and two air abrasion methods), demonstrated significantly better sealing (P < 0.01) than the control group and the other groups tested.
Air Abrasion, Dental↗
The influence of matrix use on microleakage in Class 5 glass-ionomer restorations.
This in vitro study examined the relationship of matrix use to microleakage in class 5 Ketal-Fil glass-ionomer restorations. Class 5 glass-ionomer restorations were placed on the facial and lingual surfaces of 40 extracted human molars. The occlusal margin was located on enamel, and the cervical margin was located on cementum or dentin. Each tooth had one restoration placed with and without the aid of a soft metal matrix. Specimens were thermocycled (1234 cycles, 6 degrees C -60 degrees C, 30-second dwell time) and immersed in 5% methylene blue dye for four hours. The teeth were sectioned occlusogingivally through the center of each restoration, viewed with an optical microscope (X10), and each restoration was scored for dye penetration around the cavity walls. The enamel and cementum margins were scored separately for the extent of marginal leakage. No difference in leakage was found between restorations placed with or without a matrix (P > 0.05). Enamel restorations leaked significantly less than nonenamel margins, regardless of matrix use (P > 0.05).
Dental Cementum↗
An analysis of selected normative tooth proportions.
This study was conducted to determine the average dimensions of the six maxillary anterior teeth in a targeted population and to evaluate the relationships between intertooth and intratooth dimensions. Casts were obtained from 54 patients ranging in age from 18 to 35. Measurements of length and width were made on the casts using a digital caliper. Using these measurements, ratios were calculated: length to width, width to width, and length to length. Although the tooth dimensions varied somewhat by race and gender, the ratios were quite consistent. In addition, the golden proportion was not found to correlate with any of the calculated ratios.
Analysis of Variance↗
Immersion disinfection of irreversible hydrocolloid impressions. Part 1: Microbiology.
This study evaluated the effectiveness of four disinfectants for irreversible hydrocolloid impressions. Impressions were made of a sterile metal model of the maxillary arch that had been contaminated with one of the following bacteria: Staphylococcus aureus, Salmonella choleraesuis, Pseudomonas aeruginosa, Mycobacterium bovis, or Bacillus subtilis. The impressions were cultured before and after immersion in one of the following disinfectants: lodofive, OMC II, 0.525% sodium hypochlorite, or Alcide LD. Alcide LD achieved a 4-log10 (99.99%) or greater reduction in colony forming units for all five organisms plus mixed oral flora. Sodium hypochlorite achieved a 4-log10 reduction in three of the five organisms and mixed oral flora. Iodofive and OMC II were ineffective against all test organisms and mixed oral flora.
Bacillus subtilis↗
Immersion disinfection of irreversible hydrocolloid impressions. Part 2: Effects on gypsum casts.
This study evaluated the quality of gypsum casts recovered from disinfected irreversible hydrocolloid impressions. Four disinfectants were evaluated: 0.525% sodium hypochlorite, Alcide LD, Iodofive, and OMC II. Water served as the control. Specimens were evaluated for roughness, surface detail, and dimensional stability. Impressions disinfected with NaOCI or Alcide produced gypsum casts with physical properties that were generally equal or superior to casts from impressions rinsed with water. OMC II and Iodofive generally produced casts inferior to the controls.
Analysis of Variance↗
Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part I: Microbiology.
Current American Dental Association infection control guidelines recommend immersion disinfection of irreversible hydrocolloid impressions, and this study further defines the parameters for use of sodium hypochlorite. Sodium hypochlorite has been shown to be an effective disinfectant for impressions; however, it has not been fully evaluated for optimum immersion time and concentration. In this study, irreversible hydrocolloid impressions contaminated with different bacteria were immersed in varying concentrations of sodium hypochlorite for 1, 5, or 10 minutes. Dilute solutions of sodium hypochlorite (0.525% or 0.0525%) produced a 4-log10 (99.99%) reduction in colony-forming units of Staphylococcus aureus, Salmonella choleraesuis, or Pseudomonas aeruginosa after 1 to 5 minutes' immersion. Full-strength sodium hypochlorite (5.25%) required 5 minutes to produce a 4-log10 reduction of Bacillus subtilis. A 4-log10 reduction of Mycobacterium bovis was not obtained under any conditions examined.
Alginates↗
The effect of air thinning on dentin adhesive bond strength.
The purpose of this study was to determine if air thinning three dentin adhesives would affect bond strength to dentin. Ninety human molars were mounted in acrylic and the occlusal surfaces ground to expose a flat dentin surface. Thirty teeth were randomly assigned to one of the following dentin bonding agent/composite combinations: A) Universal Bond 3/TPH (Caulk), B) All-Bond 2/Bis-Fil-P (Bisco), and C) Scotchbond Multi-Purpose/Z-100 (3m). The primers were applied following the manufacturers' instructions. The adhesives were applied by two methods. A thin layer of adhesive was applied with a brush to 15 specimens in each group and light cured. Adhesive was brushed on to the remaining 15 teeth in the group, air thinned for 3 seconds, and then polymerized. The appropriate composite was applied in 2 mm increments and light cured utilizing a 5 mm-in-diameter split Teflon mold. Following 3 months of water storage, all groups were shear tested to failure on an Instron Universal Testing Machine. Bond strength was significantly higher in all groups when the dentin bonding agent was painted on without being air thinned. Scotchbond Multi-Purpose had significantly higher bond strength than All-Bond 2, which had significantly higher bond strength than Universal Bond 3.
Air↗