Funda Kont Cobankara

In vitro antibacterial activities of root-canal sealers by using two different methods.

The purpose of this in vitro study was to evaluate the antibacterial activity of five different root-canal sealers (RoekoSeal, Ketac-Endo, AH Plus, Sealapex, Sultan). With the use of Enterococcus faecalis as a test organism, both the agar-diffusion test (ADT) and direct-contact test (DCT) were performed. For DCT, sealers were mixed and placed on the sidewall of microtiter plate wells. A 10-microl bacterial suspension was placed on the tested material samples. Bacteria were allowed to directly contact to the sealers for 1 h at 37 degrees C. Bacterial growth was then spectrophotometrically measured through every 30 min for 19 h by using an Anthos Labtec HT 2. For ADT, a 200-microl bacterial suspension was spread on brain-heart infusion agar plates. Freshly mixed sealers were poured into uniform wells punched in the agar. After periods of incubation at 37 degrees C for 24 h and 7 days in humid atmosphere, the zones of inhibition of bacterial growth on agar plates were observed and measured. Ketac-Endo, Sultan, and AH Plus had similar results for DCT. These sealers were more potent bacterial-growth inhibitors than Sealapex and RoekoSeal. According to ADT, RoekoSeal showed no antibacterial activity. There was no significant difference among AH Plus, Sealapex, and Sultan (p > 0.05). Ketac-Endo demonstrated lower antimicrobial activity than these sealers (p < 0.05). Time had no effect on the antibacterial activity of the tested sealers (p > 0.05). The antibacterial efficiency of the materials varied according to the tests used. It was concluded that the technique, time, and ingredients of the tested material can affect the results of the microbiological studies.

The Effect of Different Restoration Techniques on the Fracture Resistance of Endodontically-treated Molars

AIM This study compared the fracture resistance of endodontically-treated mandibular molars with mesio-occluso-distal (MOD) cavities restored using different restoration techniques. METHODOLOGY Sixty sound extracted mandibular molars were randomly assigned to six groups (n=10). Group 1 did not receive any preparation. The teeth in Groups 2-6 received root canal treatment and a MOD cavity preparation. The teeth in Group 2 were kept unrestored. Group 3 was restored conventionally with amalgam. Group 4 was restored with a dentin bonding system (DBS, Clearfil SE Bond) and resin composite (CR) (Clearfil Photoposterior). Group 5 was restored with indirect hybrid ceramic inlay material (Estenia). In Group 6, polyethylene ribbon fiber (Ribbond) was inserted into cavities in a buccal-to-lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens, except for Group 2, were loaded to failure by a chewing simulation device (60,000 cycles x 50 N load, 1.3 Hz frequency) in an artificial environment at 37 degrees C. Each tooth was subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/minute. The mean loads necessary to fracture were recorded in Newtons and the results were statistically analyzed. RESULTS The mean fracture values were as follows: Group 1: 2485.3 +/- 193.98a, Group 2: 533.9 +/- 59.4a, Group 3: 1705.8 +/- 135.7a, Group 4: 2033.3 +/- 137.6cd, Group 5: 2121.3 +/- 156.5d, Group 6: 1908.9 +/- 132.2cd. There were statistically significant differences between the groups annotated with different letters. Thus, Group 1 (intact teeth) had the greatest fracture resistance and Group 2 (non-restored teeth) the poorest. No statistically significant differences were found between Groups 3 (amalgam), 4 (resin composite) and 6 (polyethylene ribbon fiber reinforced composite) (p > 0.05). Group 5 (indirect hybrid ceramic inlay) had greater fracture resistance than Group 3 (p < 0.05). CONCLUSIONS Within the limitations of this study, although all of the restoration groups were stronger than the prepared-only group, none of the restoration techniques tested was able to completely restore the fracture resistance lost from MOD cavity preparation. However, use of indirect hybrid inlay restorations in these teeth may be recommended, because this restoration technique indicated more favorable fracture failure modes than other restoration techniques used in this study and particularly greater fracture strength than amalgam restorations. The promising result of indirect hybrid inlay restorations may need to be confirmed by long-term clinical studies.

The Effect of Two Different Root Canal Sealers and Smear Layer on Resistance to Root Fracture

The purpose of this in vitro study was to test the effect of Ketac-Endo (KE) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer. Seventy-two human maxillary canine teeth were randomly divided into six groups (n = 12) and were prepared using six different methods: group 1: KE, without smear layer (smear -); group 2: KE, with smear layer (smear +); group 3: AH 26, smear (-); group 4: AH 26, smear (+); group 5 (negative control): nonprepared; group 6 (positive control): prepared but unfilled. After storing 1 week in 100% humidity at 37 degrees C, the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots. The samples were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially designed steel pad at an angle of 15 degrees to the long axis of the root. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests. The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture (p < 0.05). The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated (p < 0.05), and there was no difference between the sealers. The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth (p > 0.05).

Long-term Evaluation of the Influence of Smear Layer on the Apical Sealing Ability of MTA

The aim of this in vitro study was to investigate the effect of the smear layer on apical microleakage in teeth obturated with mineral trioxide aggregate (MTA). Fifty single-rooted central maxillary teeth were used in this study. All teeth were instrumented to size 60 by using the step-back technique. The selected teeth were randomly divided into 2 groups (n = 20). In the first group (smear [+]), the teeth were irrigated with only NaOCl (5.25%). In the second group (smear [-]), the teeth were irrigated with ethylenediaminetetraacetic acid (EDTA) (17%) and NaOCl (5.25%) to remove the smear layer. The teeth were then filled with MTA. The computerized fluid filtration method was used for evaluation of apical microleakage. The quantitative apical leakage of each tooth was measured after 2, 30, and 180 days. Statistical analysis was done with the Mann-Whitney U and Wilcoxon signed ranks tests. At the end of this study there was no difference in 2 days between the groups, but removal of the smear layer caused significantly more apical microleakage than when the smear layer was left intact for 30 and 180 days (P < .005). Within the constraints of this study it can be concluded that the apical microleakage of MTA is less when the smear layer is present than when it is absent.

Effect of a new restoration technique on fracture resistance of endodontically treated teeth

The aim of the study was to investigate the effect of a new fiber-reinforced composite restoration technique on fracture resistance in endodontically treated premolars. Eighty sound extracted human mandibular premolars were assigned to four groups (n = 20). Group 1 did not receive any treatment. In groups 2, 3 and 4, the teeth received root canal treatment and a mesio-occluso-distal cavity preparation. Group 2 was kept unrestored. Group 3 was restored with a dentin bonding system and composite resin. In group 4, a piece of polyethylene ribbon fiber was inserted into the groove in a buccal to lingual direction during the restoration of teeth with dentin bonding system and composite resin. After finishing and polishing, the specimens were stored in 100% humidity at 37 degrees C for 24 h and placed at an angle of 45 degrees to the long axis of the tooth and subjected to compressive loading in a universal testing machine at a crosshead speed of 0.5 mm min(-1). The load necessary to fracture the samples was recorded in Newton (N) and submitted to Kruskal-Wallis anova and Mann-Whitney U-test. The fracture strength of the teeth reinforced with a combination of polyethylene fiber and composite resin were not significantly different than those that were restored with only composite resin (P > 0.05). However, most of the failure modes of the reinforced teeth were limited to the level of the enamel, while the other three groups showed fractures generally at the level of the dentin, cemento-enamel junction or more below (P < 0.05). Therefore, polyethylene ribbon fiber-reinforced composite resin restorations seemed a more reliable restorative technique than traditional composite restorations for extensive cavities.

Comparison of organic tissue dissolution capacities of sodium hypochlorite and chlorine dioxide.

The organic tissue dissolution properties of irrigating solutions are important for the success of endodontic treatment. Chlorine dioxide (ClO2) has been recently proposed as an irrigation solution in endodontics. The organic tissue dissolution property of sodium hypochlorite (NaOCl) is well-known and extensively investigated, but apparently no data have been published on tissue-dissolving properties of ClO2. The aim of this in vitro study was to compare organic tissue dissolution capacity of NaOCl and ClO2. In this study, 5.25% NaOCl, 13.8% ClO2, and, as a control, isotonic saline solutions (0.9% NaCl) were used. Thirty bovine pulp specimens were previously weighed and immersed for 20 minutes in each test solution (changing the solution every 2 minutes). The pulp specimens were then blotted dry and weighed again. The percentage of weight loss was calculated and statistically analyzed by using one-way analysis of variance and post hoc Tukey honestly significant difference tests. Saline solution did not dissolve the organic tissue. Both 5.25% NaOCl and 13.8% ClO2 dissolved the tissue pieces more effectively than saline control (P < .05). No statistically significant difference was found between the tissue-dissolving properties of 5.25% NaOCl and those of 13.8% ClO2 (P > .05). Within the limitations of this in vitro study, it was concluded that ClO2 and NaOCl are equally efficient for dissolving organic tissue.

Effects of chelating agents on the mineral content of root canal dentin

OBJECTIVE The objective of this in vitro study was to assess the effect of several chelating agents on the mineral content of root dentin. STUDY DESIGN Extracted human mandibular incisor roots were prepared and divided into groups according to the following irrigation protocols: 1) 17% ethylenediaminetetraacetic acid (EDTA); 2) 10% citric acid solution; 3) 18% etidronate; 4) 2.25% peracetic acid; 5) and deionized water (control). Dentin chips were obtained (Gates-Glidden nos. 3, 4, and 5). The levels of different minerals were analyzed with the use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). RESULTS 1) Peracetic acid significantly decreased P, K, Mg, Na, and S levels compared with the other groups (P < .05). 2) S decreased by different levels in all of the chelating solutions (P < .05), and the greatest decrease was observed in peracetic acid. 3) Ca levels significantly decreased in peracetic acid, citric acid, and EDTA (P < .05). 4) Mn levels significantly decreased in the citric acid and peracetic acid groups (P < .05). 5) Na and Zn levels significantly decreased in the peracetic acid, citric acid, and etidronate groups (P < .05). CONCLUSIONS The chelation agents can create different effects on mineral contents of root dentin, so it is important to know what effects each solution will have on root dentin before their clinical use. In addition, according to the results of this in vitro study, it might be recommended that peracetic acid, in particular, should be used with caution.

Effect of Immediate and Delayed Post Preparation on Apical Microleakage by Using Methacrylate-based EndoREZ Sealer with or without Accelerator

The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the apical sealing ability of EndoREZ, a methacrylate-based dual-cured resin sealer, with or without accelerator. Fifty extracted human teeth were endodontically prepared and randomly divided into 6 groups. Teeth in experimental groups 1, 2, 3, and 4 (n = 10) were filled with resin-coated gutta-percha and either EndoREZ with accelerator (A+) or EndoREZ without accelerator (A-) by the lateral compaction technique. In group1 (A+) and group2 (A-), the post space was prepared immediately at the time of obturation. In groups 3 (A+) and 4 (A-), the post space was prepared after storage in 100% humidity at 37 degrees C for 1 week. Groups 5 and 6 (n = 5) represented positive and negative control groups, respectively. Leakage was determined by computerized fluid filtration device. Complete leakage was observed in group 5, and no leakage was evident in group 6 (P = 1.000). In experimental groups, mean apical microleakage values (microL/cmH(2)O/min(-1)) were as follows: group 1, 2.77 +/- 0.79(a); group 2, 2.88 +/- 1.38(a); group 3, 19.95 +/- 7.85(c); group 4, 6.20 +/- 2.09(b) (different letters indicate significantly different groups, P < .005). Immediate post space preparation achieved better sealing than delayed post preparation at the apical end, regardless of whether the EndoREZ accelerator was used. There was no significant difference between the (A+) and (A-) in immediate post space preparation. However, more leakage was found when using (A+) than (A-) in delayed post preparation. Under the conditions of this study, it was concluded that EndoREZ accelerator seems not to provide clinicians with any advantage for rapid transition from endodontic treatment to post-endodontic restorative procedures immediately after completion of root canal therapy.

Effect of Unintentionally Extruded Calcium Hydroxide Paste Including Barium Sulfate as a Radiopaquing Agent in Treatment of Teeth with Periapical Lesions: Report of a Case

Calcium hydroxide [Ca(OH)2] has been widely used as short- or long-term intracanal antibacterial dressing material after endodontic treatment. In general when used in endodontics, Ca(OH)2 paste is composed of the powder, a vehicle, and a radiopacifier. To provide radiopacity, barium sulfate (BaSO4) powder is usually added to the paste. In this case report, BaSO4:Ca(OH)2 powders (ratio 1:8) and distilled water were mixed and applied as dressing material after root canals of mandibular left canine and premolar teeth with periapical lesions. However, the prepared paste was unintentionally extruded into the periapical lesion during application. The patient was seen 12 and 36 months later, at which point periapical healing was evaluated. At this time, it was observed that the periapical lesion had disappeared, but white radiopaque spots were seen at the place where calcium hydroxide remnants had originally been present. The presented case report reveals that when Ca(OH)2 paste that included BaSO4 was applied as an intracanal dressing and extruded through the periapical lesion associated with pulpless teeth, it had no detrimental effect. However, healing might take longer when Ca(OH)2 paste including BaSO4 is used, so deliberate overextension is not advocated.

Maxillary first molar with an unusual morphology: report of a rare case

Variations in dental anatomy are found in all teeth. Knowledge of these variations, particularly concerning the location and treatment of all canals, is very important for the success of endodontic therapy, because the inability to find and properly treat the root canals may cause failures. Variations in canal morphology, such as extra canals, apical ramifications, apical deltas, or lateral canals, are commonly encountered, and their incidence and significance have been well documented. However, the clinician should also be aware of the possibility of the existence of fewer root and/or canal numbers. The goal of this clinical article is to describe root canal treatment in a maxillary first molar with the unusual morphology of a single root and a single canal.