Effect of pre-heating resin composite on restoration microleakage.

Improving the adaptation of resin composites during placement is necessary to increase durability and reduce microleakage. Flowable resin liners have been introduced to improve adaptation in composite restorations. In addition, a device that lowers the viscosity of regular dental composites has been introduced (Calset, AdDent Inc, Danbury, CT, USA). This device lowers the viscosity of composites by preheating them to 54.4 degrees C, which should lead to improved adaptation. This study compared microleakage in Class II composite restorations prepared using: 1) preheated resin composite, 2) unheated composite and 3) a flowable liner followed by unheated composite. Class II cavities were prepared on the mesial and distal surfaces of extracted third molars. Ten preparations were restored with resin composite (Esthet-X, Dentsply, York, PA, USA) for each of the following four techniques: Control (Esthet-X with Prime & Bond NT, Dentsply), Flowable (f) (as Control but used Esthet-X Flow liner), Preheated (p) (as Control but with preheating composite to 54.4 degrees C) and Delay (d) (as Preheated but followed by a 15-second delay before curing). The teeth were restored, finished, stored in distilled water for 24 hours, then thermocycled between water bath temperatures of 5 degrees C and 55 degrees C with a one-minute dwell time for 1000 cycles. Tooth apices were sealed with epoxy and varnish was applied to within 1 mm of the restoration margins. The teeth were placed in 0.5% basic fuschin dye for 24 hours, rinsed, then embedded in self-curing resin. The embedded teeth were sectioned mesiodistally with a slow-speed diamond saw, providing multiple sections per restoration. Microleakage was rated by two evaluators using a 0-4 ordinal scale at the occlusal and cervical margins of each restoration and light microscopy (40x). The data were analyzed with Kruskal-Wallis ANOVA and pairwise testing with the Sign test (alpha=0.05). No statistical differences were observed among materials at the occlusal margin. However, at the cervical margin, the preheated samples P showed statistically lower microleakage than the controls and all other treatments. The D samples showed higher microleakage than the P and F samples. Ranked sum scores for the cervical were D (4516), C (3974), F (2756) and P (1958). There was a statistically greater amount of leakage at the cervical margins compared to the occlusal p<0.05. Preheating the composite resulted in significantly less microleakage at the cervical margins compared to the flowable liner and control. Delaying light curing of the preheated composite for 15 seconds (D) was counterproductive and led to increased microleakage.

Effect of a blueberry nutritional supplement on macronutrients, food group intake, and plasma vitamin E and vitamin C in US athletes.

Antioxidants from a blueberry beverage may impact plasma vitamins. We examined vitamins/food selection in 12 college athletes during 30 days compared with placebo. Blood was collected before and after exercise at the beginning of the study (day 1) and then after a 30-day period of taking a daily supplemental beverage (day 30). The six trials involved blood that was drawn pre-beverage ingestion/pre-exercise (trials 1 and 4), post-beverage ingestion/pre-exercise (trials 2 and 5), and post-beverage ingestion/1 h post-exercise (trials 3 and 6), on day 1 (trials 1, 2, and 3) and day 30 (trials 4, 5, and 6). Analysis of variance revealed non-significant differences for macronutrient or gamma-tocopherol and vitamin C intakes by food frequency questionnaire or plasma vitamins by liquid chromatography. There was a trend (P = 0.083) in the group x time interaction for alpha-tocopherol intake by repeated-measures analysis of variance. Blueberry alpha-tocopherol (23.91 +/- 9.31 mg) was significantly (P < 0.05) higher than placebo alpha-tocopherol intake (7.59 +/- 0.95 mg) on day 1, but not on day 30 (blueberry, alpha-tocopherol = 9.04 +/- 2.35 mg, placebo, alpha-tocopherol = 11.46 +/- 3.65 mg) by pairwise comparisons. Blueberry supplementation did not affect plasma vitamin concentrations or gamma-tocopherol and vitamin C intakes, and may reduce alpha-tocopherol intake in those starting with a higher alpha-tocopherol intake, yet not altering athletes' eating habits.

Accuracy of film-based, digital, and enhanced digital images for endodontic length determination.

OBJECTIVE: This study compared the accuracy of D- and F-speed intraoral radiographs and digital and enhanced digital radiographic images for endodontic file length determination. STUDY DESIGN: Size 15 K-files were bonded in 51 canals of 34 human cadaver teeth. The distance from file tip to root apex was measured on D- and F-speed film and on unenhanced and enhanced digital images. The quality of the images was rated by the observers. Overlying cadaver bone and root structure were subsequently removed to expose the file tip for actual measurement to the apex. The distance measured on each image was compared with the actual measurement. ANOVA, Kruskal-Wallis, sign test, and Pearson correlation statistical analyses were applied. RESULTS: There were no significant differences in measurement accuracy among the 4 image types (P < or = .05). Subjective ratings showed a preference for the quality of enhanced digital images. Conclusion All 4 image types were similar in accuracy of file measurement. The image quality of enhanced digital images was subjectively superior to the others.

Evaluation of surface finish and polish of eight provisional restorative materials using acrylic bur and abrasive disk with and without pumice.

This study evaluated the effects of two finishing techniques and pumice polishing on the surface roughness of eight different provisional materials. Provisional materials included polymethylmethacrylate-based Alike, Snap, Trim and Jetand composite-based provisional materials Temphase, Protemp 3 Garant, Luxatemp and Integrity. Baseline surface roughness was measured by a profilometer, then the provisional materials were finished using extra fine acrylic burs or medium abrasive disks. The surface roughness of each sample was measured following finishing using a profilometer as previously stated. Each surface was then polished with pumice and the surface roughness was measured again. The data were analyzed using repeated measures of ANOVA and Bonferroni pairwise comparisons (alpha = 0.05). The results indicated that with composite provisional materials, the unfinished surfaces are smoother than with bur or abrasive-disk finished surfaces. Pumice application did not smooth the surface finish for all materials. The different types of provisional materials required different finishing techniques to produce the smoothest finishes.

The effect of prophylactic polishing pastes and toothbrushing on the surface roughness of resin composite materials in vitro.

Polishing composite restorations at recall prophylaxis may affect their surface roughness. This investigation evaluated the effect of prophy paste on the surface roughness of a microfilled (Filtek A110) and a microhybrid (Filtek Z250) resin composite before and after simulated toothbrushing. Twenty, two-sided samples of both materials were fabricated in acrylic molds against a Mylar strip (baseline). Three roughness readings were recorded for each surface using a Surfanalyzer 5400 to determine the mean roughness. The samples were finished and polished with the Sof-Lex disk system and the surface roughness (Ra) was re-measured. Samples were randomly assigned and five surfaces for each material were polished with Nupro coarse, medium, fine or Clinpro prophy paste and the surface roughness measured again. All surfaces were brushed 60,000 times at 1.5Hz using a 2N brush-head force (Manly V-8 cross-brushing machine) in a 50:50 (w/w) slurry of toothpaste and water. The surface roughness was measured followed by the application of prophy paste as previously described and this final roughness recorded. Data were analyzed using repeated measures two-factor ANOVA with TUKEY HSD pairwise comparison as appropriate (alpha = 0.05). No significant difference in surface roughness was determined between the microfilled and microhybrid materials at baseline or disk treatment, yet significant differences were observed following brushing and/or prophy paste application. In conclusion, although baseline and disk treated surfaces were not significantly different in microfilled versus microhybrid composites, subsequent prophy paste application and/or simulated toothbrushing caused significant differences.

The effect of automated nonroller processing on the sensitometric characteristics of 3 intraoral film types.

OBJECTIVES: We sought to compare the sensitometric characteristics of 3 intraoral film types processed in an automated roller solution with the characteristics of the films processed in 4 automated nonroller solutions. STUDY DESIGN: Eastman Kodak Ultra-Speed, Flow X-ray EV-57, and Eastman Kodak InSight films were exposed to varying levels of radiation and processed in 1 automated roller solution and in 4 nonroller solutions. Speed and contrast were measured at various density levels and ranges. RESULTS: With the exception of 1 nonroller solution, there was little difference in speed between roller and nonroller processing chemicals at various density levels. Some nonroller solutions were faster than the roller chemicals for all films. Nonroller processing mostly increased contrast compared with roller processing over various ranges. CONCLUSIONS: Sensitometric properties of films processed in automatic nonroller solutions are comparable in many cases to those in roller solutions, sometimes resulting in greater speed and contrast. Different adjustments in exposure factors are required for specific film/processing combinations.

Contemporary endodontic retreatments: an analysis based on clinical treatment findings.

A prospective in vivo investigation was conducted to determine radiographic and clinical factors associated with contemporary nonsurgical endodontic retreatments. Approximately 1,100 failing endodontically treated teeth were screened to determine an appropriate treatment plan. Using magnification, 337 consecutive retreatment cases were evaluated and treated. The vast majority of the retreated cases involved multiple factors. Eighty-five percent of the cases presented with periradicular radiolucencies. Sixty-five percent of the cases demonstrated poor radiographic obturation quality. Associated pain was noted 51% of the time. Forty-two percent of the teeth had untreated canal space. It was statistically significant (Chi-square, p < or = 0.05) that additional canal space was located and treated in 89% of the cases that had previous radiographic asymmetrical obturations. Evidence of coronal leakage was noted in 13% of the retreated teeth. Tooth number, obturation materials, overfills, and previous surgical retrofillings were also recorded. Recommendations were made that might improve the rate of clinical success.

Microleakage of Class II packable resin composites lined with flowables: an in vitro study.

Flowable resin materials have been suggested as liners beneath packable composites to improve marginal integrity. This investigation evaluated the effect of low-viscosity liners on microleakage in Class II packable composite restorations. Twenty Class II cavities were prepared in extracted third molars for each of four packable composites (Heliomolar HB, Prodigy Condensable, Surefil and Tetric Condense). Ten restorations were placed for each material with their corresponding bonding agent per manufacturer's suggestion; in addition, 10 were placed with the flowable liner recommended by the manufacturer for that material. Samples were finished, stored in distilled water for at least 24 hours and thermocycled for 1,000 cycles between 5 degrees and 55 degrees C with a one-minute dwell time. Apices were sealed with epoxy cement and the teeth were varnished to within 1 mm of the margins. Samples were placed in 0.5% basic fuschin dye for 24 hours, rinsed, embedded in resin and sectioned to produce multiple sections. Microleakage was rated (0-4 ordinal scale) at both the occlusal and cervical margins. Data were analyzed with Kruskal-Wallis ANOVA for main effect and ranked sum analysis for pairwise testing (alpha = 0.05). All materials, either separately or in combination with a flowable liner, had greater leakage scores at the cervical margin compared to the occlusal margin. All packable systems tested did not yield a reduction in microleakage with the use of a flowable liner in vitro; however, the packable system with the flowable compomer used as a liner yielded significantly less overall microleakage compared to the three systems that used a resin composite liner.

Implant dentistry in predoctoral education: the elective approach.

In response to interest by dental students and patient needs, an elective program in implant dentistry was started at the University of Detroit Mercy School of Dentistry (UDM) in the summer of 1994. The 1-year program is offered to a group of 10 senior students out of a class of 72. Implant treatment is provided to selected edentulous and partially edentulous patients. Predoctoral students participate in diagnosis and treatment planning, assist in surgical placement, and perform the prosthodontic procedures. A survey was sent to 160 UDM graduates, and 90 responded. Out of the 90 respondents, 35% had participated in the elective implant program and 65% had not. A Pearson correlation matrix was used to analyze their responses. A stronger positive correlation with offering and restoring implants was seen in graduates who had completed the elective program in implant dentistry.