Paul D. Eleazer

Scanning electron microscopic study of the efficacy of various irrigating solutions

Fifty-four freshly extracted single-rooted teeth were mechanically instrumented until clean, white shavings were obtained. The following agents were used for irrigation: physiologic saline solution, hydrogen peroxide, sodium hypochlorite, hydrogen peroxide and sodium hypochlorite, Glyoxide, Glyoxide and sodium hypochlorite, RC Prep, RC Prep and sodium hypochlorite, ethylenediaminetetraacetic acid (EDTA), and EDTA and sodium hypochlorite. The teeth were then prepared for examination with a scanning electron microscope. Photomicrographs were taken of the apical, middle, and coronal thirds. The effectiveness of the irrigation solutions in removing debris and microbes was assessed. There seemed to be no apparent difference in the effectiveness of any of the tested solutions in removing root canal debris. Significantly less debris was removed when no irrigant was used.

pH Required to Kill Enterococcus faecalis in Vitro

Enterococcus faecalis tolerates highly alkaline environments, yet the exact pH required for killing E. faecalis is not known. This study tests growth at 0.5 increments from pH 9.5 to 12. Twelve culture tubes were used in each group. Positive growth was measured using turbidity, a visual scale, and a spectrophotometer. At 24 h, growth was observed in all tubes at pH 9.5 and 10. At 48 h, all pH 10.5 tubes showed growth. At 72 h, six of the pH 11 tubes showed growth. After 7 days, five of the remaining pH 11 tubes were positive. No growth occurred in any of the pH 11.5 or pH 12 tubes. Apparently, pH 10.5 to 11.0 retards growth of E. faecalis, whereas no tubes showed growth at pH 11.5 or greater.

The Effect of Three Commonly Used Endodontic Materials on the Strength and Hardness of Root Dentin

The purpose of this study was to determine if calcium hydroxide, mineral trioxide aggregate, or sodium hypochlorite caused a change in the force required to fracture root dentin. Ten bovine central and lateral incisors were machined using various saws and drills to produce a cylinder of dentin with a 6.0-mm outer diameter 3.5-mm inner diameter and a length of 10 mm. The cylinders were cut lengthwise into four symmetrical pieces. The canal sides of the sections were then placed into Petri dishes containing a 1-mm depth of calcium hydroxide, mineral trioxide aggregate, sodium hypochlorite, or physiologic saline (control). The samples remained in the dishes for 5 weeks and were then shear tested by using an Instron machine. Data were analyzed using an ANOVA test for comparison of the groups as a whole, and a t test was used to compare each quarter section with its control from the same tooth. A 32% mean decrease in strength was discovered for calcium hydroxide, a 33% decrease in strength for mineral trioxide aggregate, and a 59% decrease for sodium hypochlorite. All decreases in strength were statistically significant: p < 0.001 for calcium hydroxide, p = 0.027 for mineral trioxide aggregate, and p < 0.001 for sodium hypochlorite. Results indicated that root dentin was weakened after 5 weeks of exposure to calcium hydroxide, mineral trioxide aggregate, or sodium hypochlorite.

Flare-Up Rate in Pulpally Necrotic Molars in One- Visit Versus Two-Visit Endodontic Treatment

This retrospective study compared one-visit versus two-visit endodontic treatment. The same technique and materials were used before and after making the sole change to one-visit endodontic treatment in 1991. Treatment records of 402 consecutive patients with pulpally necrotic first and second molars were compared. In 201 patients, treatment was provided by debridement and instrumentation, followed by obturation at a second visit; whereas the second group received single visit therapy. Flare-ups were defined as either patient reports of pain not controlled with over-the-counter medication or as increasing swelling. Sixteen flare-ups (8%) occurred in the two-visit group versus six flare-ups (3%) for the one-visit group. This showed an advantage for one-visit treatment at a 95% confidence level. In a second comparison, one-visit patients who had previously received two-visit treatment for a different pulpally necrotic molar served as their own control. No significant differences were present in this subgroup of 17 patients.

Detoxification of Endotoxin by Endodontic Irrigants and Calcium Hydroxide

The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.

Effect of lowering the pH of sodium hypochlorite on dissolving tissue in vitro.

Sodium hypochlorite (NaOCl), a common antimicrobial and tissue-dissolving irrigant, comes from the manufacturer at pH 12. When the pH is lowered, NaOCl becomes more antimicrobial. The aim of this study was to examine what effect lowering the pH has on the property of tissue dissolution. Seven groups were tested for dissolving porcine muscle tissue at varying pH, concentrations, and times. When groups were examined solely by pH, there was no significant difference between the pH 12 and 9 groups, but a statistically significant level was found between pH 12 and 9 versus the pH 6 groups (P < .05). Higher concentrations and greater time periods all led to greater amounts of tissue dissolution.

Comparison of Success of Implants versus Endodontically Treated Teeth

Implants verses root canal therapy is a current controversy in dentistry. The purpose of this investigation was to compare the success of each treatment, with minimal subjective grading. Outcome was determined by clinical chart notes and radiographs. Failure was defined as removal of the implant or tooth. Uncertain findings for implants were defined as mobility class I or greater, radiographic signs of bone loss, or an additional surgical procedure. Mobility, periapical index score of 3 or greater, or the need for apical surgery was classified as uncertain for endodontically treated teeth. Success was recorded if the implant or tooth was in place and functional. Implants were placed by periodontists in a group practice, whereas the endodontic treatments were performed by endodontists in group practice. Charts of 129 implants meeting inclusion criteria showed follow-up of an average of 36 months (range, 15-57 months), with a success rate of 98.4%. One hundred forty-three endodontically treated teeth were followed for an average of 22 months (range, 18-59 months), with a success rate of 99.3%. No statistically significant differences were found (P = .56). When uncertain findings were added to the failures, implant success dropped to 87.6%, and endodontic success declined to 90.2%. This difference was not statistically significant (P = .61). We found that 12.4% of implants required interventions, whereas 1.3% of endodontically treated teeth required interventions, which was statistically significant (P = .0003). The success of implant and endodontically treated teeth was essentially identical, but implants required more postoperative treatments to maintain them.

Effectiveness of various medications on postoperative pain following root canal obturation

This prospective study compared the effectiveness of nine medications and a placebo in controlling pain following obturation. A total of 588 patients who required root canal obturation were included. After obturation of root canals, each patient took one of the medications, salicylic acid (2 x 250 mg), acetaminophen (2 x 250 mg), ibuprofen (2 x 250 mg), ketoprofen (2 x 250 mg), acetaminophen (2 x 250 mg) plus codeine (2 x 250 mg), penicillin (2 x 250 mg), erythromycin base (2 x 250 mg), penicillin plus ibuprofen (2 x 250 mg), methylprednisolone (2 x 250 mg) plus penicillin (2 x 250 mg), or a placebo, every 6 h for 72 h. All medications were encapsulated in identical capsules. The patients registered their degree of discomfort on a visual analogue scale of 0 to 9. Statistical analysis of the data showed that the incidence of postoperative pain after obturation is lower than that following complete cleaning and shaping (5.83% versus 21.76%). In addition, there was no significant difference between the effectiveness of the various medications and placebo tablets in controlling postoperative pain following obturation.

Comparison of Classic Endodontic Techniques versus Contemporary Techniques on Endodontic Treatment Success

INTRODUCTION Many recent technological advancements have been made in the field of endodontics; however, comparatively few studies have evaluated their impact on tooth survival. This study compared the survival rates of endodontic treatment performed by using classic techniques (eg, instrumentation with stainless steel hand files, alternating 5.25% NaOCl and 3% H2O2 irrigation, mostly multiple treatment visits, and so on) versus those performed using more contemporary techniques (eg, instrumentation with hand and rotary nickel-titanium files, frequent single-visit treatment, NaOCl, EDTA, chlorhexidine, H2O2 irrigation, warm vertical or lateral condensation obturation, use of surgical microscopes, electronic apex locators, and so on). METHODS Using a retrospective chart review, clinical data were obtained for 984 endodontically treated teeth in 857 patients. Survival was defined as radiographic evidence of the treated tooth being present in the oral cavity 12 months or more after initial treatment. A mixed-model Poisson regression analysis was used to compare failure rates. RESULTS Of the 459 teeth in the classic group, there was an overall survival rate of 98% with an average follow-up time of 75.7 months. Of 525 teeth in the contemporary group, there was an overall survival rate of 96%, with an average follow-up time of 34 months. Considerably more treatments in the classic group were completed in multiple appointments (91%) than in the contemporary group (39%). More teeth in the classic group underwent posttreatment interventions (6.7% vs 0.9%, respectively). CONCLUSIONS No statistically significant difference was noted between the two technique groups or between single or multiple visits in terms of survival.

Effect of a Separated Instrument on Bacterial Penetration of Obturated Root Canals

The aim of this study was to determine the effect a separated instrument has on the time required for bacterial penetration of obturated root canals. Twenty-six extracted human mandibular premolars with single canals were used in the study. Group 1 consisted of teeth that contained a separated size 40 Profile rotary file and were obturated with gutta-percha and zinc oxide eugenol sealer to the level of the separated file. Group 2 consisted of teeth that were similarly obturated, but without a separated file. The negative control canals were obturated and had the entire root surface sealed with nail polish. The positive controls were obturated without sealer. Streptococcus sanguis was placed in the access chamber daily, and penetration was determined when turbidity was noted in the culture broth. The results showed no significant difference between the two experimental groups.