Cemil Yesilsoy

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.

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 Grossmans 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. Grossmans 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.

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

Grossmans 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. Grossmans 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 Grossmans 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 Grossmans sealer and CRCS did not have overall favorable histologic reactions; however, Grossmans sealer and CRCS have been used successfully clinically. Further clinical studies are needed.

A comparative leakage study of P-30 resin bonded ceramic, teflon, amalgam, and IRM as retrofilling seals

Thirty-six recently extracted teeth were used to evaluate the leakage characteristics of the following materials as retrofilling seals: cold-burnished guttapercha, P-30 with Scotchbond, a recently developed Teflon material, amalgam, and IRM. The teeth were instrumented and obturated with gutta-percha and Kerrs Sealapex. Apical bevels were placed on all of the teeth and class I preparations were prepared and obturation was with the various materials. The teeth were then subjected to an India ink solution. After splitting the teeth, a longitudinal measurement of dye penetration was done. The results showed that IRM, Teflon, and P-30 had statistically significantly less leakage than amalgam. The best results were shown by Teflon and P-30. Clinically, Teflon was the simplest to use.

Effects of endodontic materials on cell viability across standard pore size filters

Seven endodontic materials were tested in vitro to evaluate their cytotoxic effects. These materials were N2, Mynol, Roth, Tubliseal, Diaket, AH26 (root canal sealers), and Life (pulp capping agent). Formocresol, an intracanal medicament with previously measured high cytotoxicity, served as a positive control and saline served as a negative control. Two types of cells (L929 and human pulp cells) were used in the Millipore filter test technique. A succinate dehydrogenase vital staining technique was used to determine the cell viability. Three different criteria were used to determine the materials cytoxic activity. The results showed that the three criteria: (a) zone size, (b) stain intensity within the affected zone, and (c) degree of cell lysis in the zone are each important in evaluating cytotoxic activity of materials. OccaSional but significant alterations in toxicity ranking occurred when different criteria were used. These can be explained on the basis of other physical or chemical properties of the tested materials. Because of the differences in intercriterion correlation, no one toxicity parameter is sufficient for relative ranking of the test materials.

Effect of F-File on removal of the smear layer: a scanning electron microscope study.

The aim of this study was to evaluate the effectiveness of F-File with NaOCl on removal of the smear layer. A total of 48 single-rooted teeth were instrumented using crown-down technique with one of the irrigation agents: distilled water, 5.25% NaOCl, RC-Prep, Glyde, MTAD or F-File with NaOCl. The remaining smear layer was scored at cervical, middle and apical thirds of the roots with SEM. In all the canals of experimental groups the coronal sections were cleaner than the middle and apical sections except with distilled water (P<0.001). In the coronal third, intensive smear layer was observed in distilled water, NaOCl and F-File groups and less smear layer in MTAD (P<0.05) and least in RC-Prep and Glyde groups. In the middle third, RC-Prep and Glyde groups had less smear layer than the other groups (P<0.001). In the apical third, there was intensive smear layer in all specimens and statistical analyses showed no significant difference among the groups (P>0.05). The F-file failed to improve the effect of NaOCl in removing smear layer.

Radiographic evidence of absorption of hydron from an obturated root canal

Hydron (poly-2-hydroxyethyl methacrylate) was introduced to medicine in 1960 (1) and since then it has been used clinically in breast reconstructive surgery (2, 3), suture coatings (4), and soft contact lenses (5). Hydron was introduced to clinical dentistry in the mid1970s by Goldman et al. (6, 7), Rising et al. (8), and Benkel et al. (9). It has been reported to be an ideal root canal filling material for the following reasons: (a) it is easy to use because it is an injectable material; (b) it is nonirritating; (c) it obturates the root canal system well; and (d) it does not support bacterial growth (710). However, recent reports have cast doubt on the ideal nature of Hydron as a root canal filling material. Langeland et al. (11) and Tanzilli et al. (12, 13), using animal models, have shown that Hydron has a high degree of absorbability. Hydron also elicited a significantly greater degree of leakage when compared with

Observation of Depth and Incidence of the Mesial Groove between the Mesiobuccal and Mesiolingual Orifices in Mandibular Molars

The purpose of this study was to analyze the mesiolingual-mesiobuccal groove indentations at the pulpal floor in mandibular first and second molars. The depth and incidence of occurrence were assessed. Sixty freshly extracted, mature teeth were kept in a 2.5% sodium hypochlorite for 5 to 7 days. The teeth were accessed without touching the floor of the chamber. The dental debris was washed thoroughly and then the patency and the presence of two mesial canals were established with a #10 file. The teeth were placed in 2.5% sodium hypochlorite for 3 to 5 days and later rinsed and air-dried before placement in centrifuge tubes. A vinyl polysiloxane impression material was injected into the chambers, and the teeth were centrifuged. The impressions were carefully removed and then measured by using a dissecting microscope and a transparent millimeter ruler. The ruler, at zero, placed at the mid-floor area of the impression and viewed from the mesial, measured (to the nearest 0.5 mm) the depth of the mesial groove between the mesiolingual and mesiobuccal canals. Due to imperfect impressions, 50 teeth were included in the study. The recorded average in depth was 1.0 mm. Some of the impressions had depths measuring 3.5 mm. This could be a significant space when considering the limitations of instrumentation techniques. There is the question of whether this area may remain untouched, thereby effecting the prognosis of treatment in both vital and nonvital teeth. Modifications in access preparation and/or an increased emphasis on irrigation and intracanal medication may be needed.

A scanning electron microscopic examination of surface changes obtained from two variable methods of precurving files: A clinical observation

This clinical observational study compared finger-bending and cotton pliers-bending methods of precurving endodontic files. Changes to the surface appearance of the flutes of the files were examined with the scanning electron microscope. Thirty-six files (#15 and 25) were used in two groups of 16 each: group A, finger bending and group B, cotton-pliers bending. A control group had four files. In each group, one-half were bent at approximately 20 degrees and the other one-half at approximately 30 degrees. The files were examined by scanning electron microscopic observation. No differences were found relative to instrument size or degree of bending. In general, the cotton plier-bent files gave the appearance of flattening of the flutes. Flattening of the finger-bent files was not observed. However, more debris accumulated on the finger-bent files. Hence, from this study it appears that finger bending is preferable to cotton pliers bending as a method for precurving of endodontic files. However, a controlled study is necessary to determine which are the preferred bending sites, degrees, and methods.