The comparative sealing ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid as root-end filling materials.

A comparison was made of the ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid to prevent the leakage of bacteria from root canals, when used as root-end filling materials. The materials were tested in a double-chamber device in which a root segment connects the upper (delivery) chamber and the lower (receiving) chamber. The root segment was prepared by having the root canal instrumented to a #45 file, and a 3-mm-deep, root-end preparation placed at the apical foramen. The canal of each root segment was filled with gutta-percha, and the root-end preparation was filled with one of three test materials, mixed according to the manufacturer's directions. Negative controls were constructed with sticky wax sealing the apical foramen. A titered suspension of radioactively (3H-thymidine)-labeled bacteria (Enterococcus fecalis) was placed into the delivery chamber, and sterile saline was placed into the receiving chamber such that the apical third of each root section was immersed. At various time points, samples were taken from the receiving chamber, and measured for 3H activity. The results indicated that (a) all the test materials leaked significantly compared with the negative controls; and (b) there was no significant difference found between the leakage rates of the three materials tested.

Antimicrobial and toxic effects of established and potential root canal irrigants.

Three dilutions of the commonly used irrigant sodium hypochlorite (0.5%, 2.5%, and 5.25%) and the potential irrigants Peridex, chlorhexidine gluconate (0.12%), and Therasol were tested. Alcohol and saline served as controls also. The in vitro portion of this study used four different microorganisms (Streptococcus mutans, Peptostreptococcus micros, Prevotella intermedius, and Porphyromonas gingivalis) to determine antimicrobial effect. Presterilized 7-mm diameter Whatman paper disks soaked with the test solution were prepared, and disks were placed onto the previously seeded agar petri dishes. Each dish was incubated aerobically or anaerobically according to the microorganisms used. An in vivo animal model (guinea pig) was used to examine subcutaneous local tissue reactions using the same materials; 0.1 ml of each test solution was injected subcutaneously into predetermined locations on the animal dorsum. Test site histological examination was done 2 h, 2 days, and 2 wk after the injections. The results of this comparative study indicate Peridex (chlorhexidine gluconate) and Therasol may have good potential for endodontic usage.

Short vs. long-term calcium hydroxide treatment of established inflammatory root resorption in replanted dog teeth.

This study examined, histologically, the healing of intentionally produced inflammatory root resorption of replanted teeth in beagle dogs, treated with short- or long-term placement of calcium hydroxide. Thirty beagle dog incisors were randomly divided into four groups. In group 1 (negative control), uninfected incisors were extracted, the roots were longitudinally grooved and the teeth were replanted within 2 min. In group 2 the root canals were artificially infected followed by extraction, longitudinal grooving, and replantation as in group 1. Radiographs were taken biweekly and at the first signs of inflammatory root resorption or at 4 weeks, the root canals were fully instrumented and medicated with calcium hydroxide. In group 2, the root canals were permanently obturated with gutta-percha and sealer after 1 week of calcium hydroxide. The teeth in group 3 were treated as described in group 2 but after 1 wk the calcium hydroxide dressing was repacked for the duration of the study. In group 4 (positive control) the teeth were treated as described in groups 2 and 3 but no endodontic treatment was performed. Twelve weeks after the initiation of the endodontic treatment, sacrifice and histological preparation were carried out. In group 1, complete cemental repair was seen in all teeth. In group 2, five of ten teeth showed complete cemental repair whereas in group 3 complete cemental repair was seen in nine of ten teeth. None of the teeth in group 4 showed cemental repair. It was concluded that long-term may be more effective than short-term calcium hydroxide treatment of established inflammatory root resorption.

Effect of different endodontic treatment protocols on periodontal repair and root resorption of replanted dog teeth.

This study examined, histologically, the healing of intentionally damaged root surfaces of replanted teeth with either uninfected or infected root canals treated with short- and long-term calcium hydroxide. Thirty beagle dog incisors were randomly divided into four groups. In group 1, uninfected obturated incisors were extracted, the roots were longitudinally grooved and the teeth were replanted within 2 min. In group 2 the root canals were artificially infected followed by extraction, longitudinal grooving, and replantation as described in group 1. Fourteen days after replantation, the root canals were fully instrumented and medicated with intracanal calcium hydroxide. One week later the root canals were permanently obturated with gutta-percha and sealer. The teeth in group 3 were treated as described in group 2 but after 1 wk the calcium hydroxide dressing was repacked for the duration of the study. In group 4 (positive control) the teeth were treated as described in groups 2 and 3 but no endodontic treatment was performed. After 8 wk, sacrifice and histological preparation were carried out. In group 1 complete cemental repair was seen in all teeth. In groups 2 and 3, complete and incomplete cemental repair was seen in seven and two teeth, respectively. An ankylotic area was present in one tooth in group 3. None of the teeth in group 4 showed cemental repair. It was concluded that short- and long-term calcium hydroxide treatment resulted in similar healing patterns when endodontic treatment is initiated 14 days after replantation of teeth.

The antimicrobial effect of various endodontic sealers.

The antimicrobial activity of an endodontic sealer can be helpful in destroying any remaining root canal microbes. Therefore it was decided to test the antimicrobial activity of several commonly used endodontic sealers. The sealers used were Grossman's sealer, Tubliseal, Calciobiotic, Sealapex, Hypocal, eucapercha, Nogenol, and AH26. Also tested were dry calcium hydroxide powder, calcium hydroxide mixed with saline, and a Teflon formulation. The microbes used were Streptococcus mutans (a gram-positive microaerophile). Staphylococcus aureus (a gram-positive facultative anaerobe), and Bacteroides endodontalis (a gram-negative obligate anaerobe). The freshly mixed sealers were placed into the prepared wells of agar plates inoculated with the test microorganisms. After varying periods of incubation, the zones of inhibition of bacterial growth were observed and measured. Grossman's sealer had the greatest overall antibacterial activity. However, AH26 had the greatest activity against B. endodontalis. The zinc oxide-eugenol-based sealers had more antimicrobial activity than either the calcium hydroxide-based sealers or eucapercha.

Management of teeth with open apexes and necrotic pulps: representative cases.

This paper briefly reviews the pros and cons of five methods used to treat a tooth with a necrotic pulp and an open apex (incompletely developed root), and presents representative treatments of open apex cases. These treatments include customized cone, short-fill, periapical surgery, apexification, and one-visit apexification.

Apexification: review of the literature.

Five methods for the treatment of teeth with an incompletely formed apex (open apex) and a necrotic pulp are discussed. The methods discussed include the use of (1) a customized cone (blunt-end, rolled cone); (2) a short-fill technique; (3) periapical surgery (with or without a retrograde seal); (4) apexification (apical closure induction); and (5) one-visit apexification. The apexification techniques, which use various formulations of calcium hydroxide to induce closure, are stressed. Based on the review of the literature and clinical experience of the authors, it was concluded that successful treatment of an immature pulpless tooth can partly result from the antibacterial and calcification-inducing action of calcium hydroxide.

A detailed analysis of four long-term silver cone root canal fillings.

Because many failures in root canal therapy have been attributed to the use of silver cones as a filling material, it was decided to examine four roots of three teeth, each of which had been successfully treated endodontically with silver cones ranging from 24 to 34 years previously. These roots, which were resected for periodontal reasons, were examined both under the scanning electron microscope and histologically. Examination with the scanning electron microscope revealed that all four cones were moderately to severely corroded. Histologic examination of two teeth disclosed corrosion products along the entire wall and, in one instance, within the dentinal tubules and apical tissue. The corrosion products, however, were most extensive in the cone that appeared to be loose fitting within the canal. The results indicated that corrosion products occurred in all of the teeth examined. Therefore, corrosion may not be the primary factor accounting for failure in teeth endodontically treated with silver cones.

A comparative tissue toxicity evaluation of established and newer root canal sealers.

Grossman's sealer, eucapercha, Endo-Fill, CRCS, Sealapex, Hypocal, and sterile saline solution (0.3 ml of each) were injected into specific dorsal subdermal tissue sites of 12 guinea pigs. The animals were killed after 6 days, 15 days, and 80 days (four per time period). Analysis of tissue response showed that, overall, Sealapex and Endo-Fill had less severe inflammatory reactions than any of the other test materials. Grossman's sealer, CRCS, and Hypocal showed principally severe inflammatory responses at both 6 and 15 days, but mild reactions at 80 days. Overall, eucapercha showed less severe inflammatory responses than Grossman's sealer, CRCS, and Hypocal. Diffuse calcification was induced by the three calcium hydroxide preparations (CRCS, Sealapex, and Hypocal). Eucapercha and Endo-Fill had minute local areas of calcification. Both Grossman's sealer and CRCS did not have overall favorable histologic reactions; however, Grossman's sealer and CRCS have been used successfully clinically. Further clinical studies are needed.

Comparison of diflunisal and an aspirin-codeine combination in the management of patients having one-visit endodontic therapy.

One hundred seventy-nine patients with asymptomatic or mildly symptomatic endodontic disease had single-visit therapy and were given either diflunisal (n = 94) or aspirin with codeine (n = 85) to control posttreatment pain. In this open-label, randomized study, diflunisal was judged superior to the aspirin-codeine combination in all major categories evaluated. Of patients receiving diflunisal, 93.6% needed the medication for only one day. In contrast, 77.7% of patients receiving aspirin with codeine needed the medication for only one day. Almost 64% of patients receiving diflunisal needed only one dose, while 32.9% of patients using aspirin with codeine needed only one dose. Four or more doses were required by 5.3% of patients receiving diflunisal and by 23.5% of patients receiving the aspirin-codeine combination. In patients receiving diflunisal, 20.2% experienced side effects. In contrast, 29.4% of patients receiving aspirin with codeine reported side effects. Thirty-five percent of patients receiving diflunisal rated the analgesic as excellent; 5.3% rated it as fair or poor. In contrast, 12.9% of patients receiving aspirin with codeine rated the analgesic combination as excellent; another 12.9% rated it as fair or poor. Diflunisal was found to be generally effective and well-tolerated, and superior to aspirin with codeine in the management of pain from endodontic treatment.

Differential sensitivity of normal human pulp and transformed mouse fibroblasts to cytotoxic challenge.

Six different lines of diploid cells from human pulp and one commonly used transformed-cell line, L929 (a continuous fibroblast line of mouse lung connective tissue origin), were challenged by sera changes, an agar-overlay toxicity test and transfilter-histochemistry-toxicity test. The normal diploid cells showed greater sensitivity than transformed cells in each test. Although a different parameter of cell toxicity was measured in each test, the data indicate greater toxic response in diploid cells by all measurements. These normal diploid human cells are more appropriate cells for toxicity testing materials for human use.