Anthony P. Joyce

Antibacterial Efficacy of Calcium Hydroxide and Chlorhexidine Gluconate Irrigants at 37°C and 46°C

This study investigated the ability of two endodontic irrigants to eliminate Enterococcus faecalis from dentinal tubules, and whether their antimicrobial action was enhanced by heat. The lumens of disks prepared from extracted bovine roots were infected with E. faecalis and incubated for 72 h. Specimens were then filled with saline, 10% calcium hydroxide (Ca(OH) 2 ), or 0.12% chlorhexidine gluconate (CHX) at 24°C or 46°C and incubated at 37°C or 46°C. The samples were then pulverized and plated to quantify residual bacteria. No statistical difference (p > 0.05) in bacterial growth was seen between the two saline groups, or between the two medication groups at a given temperature. CHX and Ca(OH) 2 at either temperature produced significantly less growth than either saline group, and CHX or Ca(OH) 2 at 46°C produced significantly less growth than either group at 37°C. Heat enhanced the antibacterial action of both experimental irrigants against E. faecalis , but heating saline produced no increase in bactericidal effect.

Sealing Ability of One-Up Bond and MTA With and Without a Secondary Seal as Furcation Perforation Repair Materials

This study investigated the ability of One-Up Bond alone and mineral trioxide aggregate (MTA), with and without a secondary seal of One-Up Bond or SuperEBA to seal saucer-shaped perforation defects in human molars. Cusps were removed, roots were amputated, and endodontic therapy completed on 40 extracted teeth. A cylindrical hole was made in each tooth from the furcation area to the chamber, into which a section of steel tubing was cemented. Intracoronal saucer-shaped defects were created over the perforation. The teeth were restored with MTA, One-Up Bond, or MTA with a secondary seal of One-Up Bond or SuperEBA. The integrity of the seal was evaluated by fluid filtration. MTA alone leaked significantly more than One-Up Bond or MTA with either secondary seal at 24 h. At 1 month, MTA, MTA plus One-Up Bond, and One-Up Bond alone were equivalent.

An In Vitro Evaluation of the Growth of Human Periodontal Ligament Fibroblasts after Exposure to a Methacrylate-based Endodontic Sealer

The cytotoxicity of Epiphany root canal sealer at various concentrations from 25-800 microg/mL on human periodontal ligament (HPDL) fibroblasts was evaluated at 1, 3, and 7 days. Controls included untreated cells and cells treated with the vehicle for Epiphany suspension. Fibroblast viability was assessed by 2 methods, crystal violet staining in 24-well plates and the fluorescence-based CyQUANT Cell Proliferation Assay in 96-well plates. Significant cytotoxicity against HPDL fibroblast growth by Epiphany was both time- and concentration-dependent. On day 1, 800 microg/mL, the highest concentration of Epiphany, showed significant cytotoxicity (P < or = .001). By day 7, all concentrations greater than 25 microg/mL showed significant (P < or = .05) loss of viability. This study demonstrated increased Epiphany cytotoxicity with an increase in concentration or exposure time.

Photoelastic comparison of stress induced by using stainless-steel versus nickel-titanium spreaders in vitro

The vertical force applied to an endodontic spreader generates stress along the canal walls. Recognizing the potential for this stress may reduce the incidence of vertical root fractures. A photoelastic acrylic model was fabricated to exhibit the stress produced during obturation of curved canals using the lateral condensation technique. Twenty standardized models simulating curved canals (32 degrees) were formed within PL-2 photoelastic acrylic resin blocks. The canals were fitted with a gutta-percha point, and either a stainless-steel or nickel-titanium finger spreader was inserted. An Instron 4502 universal testing machine applied a vertical force of 20 Newtons to the spreader. Quarter wave and polarizing filters were used with backlighting to generate the fringe patterns in the models. Photographs of the resulting stress lines showed that the stainless-steel spreaders created three areas of concentrated stress. The nickel-titanium spreaders induced stress patterns spread out along the surface of the canals, thus reducing the concentration of stress and the potential for vertical root fracture.

Evaluation of the effectiveness and comfort of incisive nerve anesthesia given inside or outside the mental foramen.

Thirty volunteer subjects were given bilateral injections of one-half carpule of 2% Xylocaine with 1:100,000 epinephrine to anesthetize the incisive nerve. Injections were given either inside or outside the mental foramen. Success (80/80 reading) and duration of anesthesia were verified with the Analytic Technology pulp tester. Pain and preference for either injection type were evaluated via questionnaire. The mental foramen could be located in 1 min 56.6% of the time. There was a significantly greater chance of success for injections given inside the foramen for the second bicuspid (p = 0.0422) and the canine (p = 0.015). There was no statistically significant difference in success for either type injection for the first bicuspid (p = 0.184). There was no significant difference in duration of anesthesia whether given inside or outside the foramen and no difference in pain of injection with either type. Patients had no clear-cut preference for either injection type.

Comparative Study of the Variability of 0.06 Tapered Rotary Endodontic Files to Current Taper Standards

This study compared the taper variation among Profile, Guidance, and EndoSequence 0.06 tapered rotary files to current standards. Fifteen files of sizes 35, 40, and 45 from each manufacturer were evaluated for a total of 135 files. A digital image of the first 4 mm of each file was captured with light microscope at 22x, calibrated for 0.001-mm accuracy, and analyzed. The diameter of each file was measured at 1 and 4 mm, and the taper was calculated. Of the 3 file systems, 100% of the Profile files, 97.8% of the Guidance files, and 86.7% of the EndoSequence files fell within +/-0.02 taper. All file systems demonstrated variability within their groups. A series of chi(2) analyses indicated that manufacturers tend to produce Guidance and Profile tapers slightly under the ideal 0.06 taper (P < .05). The tapers of EndoSequence files were just as likely to be over or under the advertised 0.06 taper (P > .05).