Bahar Özçelik

Root canal morphology of maxillary premolars.

The objective of this study was to investigate further internal anatomy of maxillary premolars. Six hundred recently extracted maxillary first and second premolar teeth were used in this study. One-half of the teeth were maxillary first premolars, the other half were maxillary second premolars. The teeth were stored in 10% formalin solution, and a standard clearing technique was applied with some modifications. Finally, ink-dyed root canal systems were evaluated by a dissecting light microscope. Each tooth was examined as to the number of roots and root canals and their types, ramifications of the main root canals, and location of apical foramina and transverse anastomoses. Examination of the root canal systems of the teeth was based on Vertuccis classification. The incidence of type I canals (one canal) for the maxillary first premolars was 8.66%, whereas 89.64% of the total samples demonstrated two canals (from type II to type VII). Only 1.66% of maxillary first premolars were type VIII or type IX (three canals). Regarding maxillary second premolars, the incidence of type I (one canal) was 48.66%, whereas it was 50.64% for type II to type VII (two canals). Type VIII (three canals) was found in 0.66% of the total sample.

pH changes and calcium ion diffusion from calcium hydroxide dressing materials through root dentin.

The purpose of this study was to evaluate Ca2+ and OH- diffusion properties through root dentin by using different calcium hydroxide (CH) dressing materials. Twenty-eight single-rooted teeth were instrumented and external defects were created on the root surface. 17% EDTA was used to eliminate the smear layer. All surfaces except the external defects were sealed, and the teeth were placed in normal saline. Ca2+ concentrations and the pH in the saline were determined for 3 days as the control period. After removing the teeth from normal saline, they were filled with: (i) DT Temporary Dressing CH; (ii) CH powder and normal saline; (iii) TempCanal; and (iv) CH points. The teeth were then placed in normal saline, and Ca2+ concentrations and pH values were measured at 1, 3, 7, 14, and 28 days. Nonsetting CH pastes gradually released Ca2+, whereas this increase was absent from CH points. None of the test materials induced a pH increase in the media during the observation period. This study demonstrated that, when nonsetting CH pastes are applied to the root canal, diffusion of Ca2+ without an increase in pH to the surrounding media occurs. This implies that these type of material are more suitable than CH points for treatment of external root resorption.

Calcium ion diffusion from mineral trioxide aggregate through simulated root resorption defects.

The purpose of this study was to investigate the diffusion of calcium ions (Ca+2) through exposed dentinal tubules following intracanal application of mineral trioxide aggregate (MTA). Fifty-two single-rooted teeth were instrumented using 2.5% sodium hypochlorite for irrigation between each file size. Thereafter, standardized defects were created on the root surfaces so as to mimic external root resorption. The root canals and external defects received a final irrigation of 17% ethylenediaminetetraacetic acid and distilled water. MTA powder was then mixed with saline and placed into the canals. All root surfaces except the cavities were sealed with two coats of varnish. Teeth with unfilled canals (n = 26) served as controls. The teeth were immersed in saline after which the release of Ca+2 from the defects into the saline was measured at 1, 3, 7, 14, and 28 days. The results showed diffusion of Ca+2 through the defects in the dentin in MTA-filled roots with a significant increase in concentration within time.

Sealing efficiency of BeeFill 2in1 and System B/Obtura II versus single-cone and cold lateral compaction techniques.

OBJECTIVE The objective of this study was to investigate the sealing properties of 2 warm vertical compaction techniques (BeeFill 2in1, System B/Obtura II) in comparison with single-cone and cold laterally compacted gutta-percha. STUDY DESIGN The root canals of single-rooted human teeth were prepared by using Mtwo rotary files and divided into 4 groups (n = 10/group) with respect to the filling technique tested: Group 1, cold laterally compacted gutta-percha + AH-26; Group 2, single-cone tapered Mtwo gutta-percha + AH-26; Group 3, System B/ObturaII + AH-26; Group 4, BeeFill 2in1 + 2seal. The leakage of specimens was measured using a fluid-filtration method after 1 and 2 weeks. The data were analyzed statistically with 2-way repeated measures ANOVA (P = .05). RESULTS After 1 week, the System B/Obtura II group showed the greatest amount of leakage(P < .05) compared with the other test groups that had similar levels of fluid conductance(P < .05). By the end of the second week, the BeeFill group yielded the greatest amount of leakage (P < .05). Compared with their 1-week values, the fluid conductance of all test groups decreased significantly (P < .05). CONCLUSION The apical sealing efficiency of System B/Obtura II and BeeFill were inferior to the other obturation techniques after 2-week fluid conductance testing in vitro.

Endothelial cell adhesion molecules in human dental pulp: a comparative immunohistochemical study on chronic periodontitis.

Migration of leukocytes to inflammation sites through vascular endothelium is controlled by the interactions of adhesion molecules expressed on both endothelial cells and leukocytes, most of which are already covered by cluster of differentiation (CD) codes. We examined the expression of a variety of endothelial cell adhesion molecules in human dental pulp vasculature to obtain further evidence on the tissue distribution and function of these molecules by using an indirect immunoperoxidase technique. We obtained the pulp tissue samples from teeth extracted due to orthodontic reasons as controls and compared with those extracted due to chronic periodontitis. In all samples, both CD31 and CD146 were expressed by arterial, venous, and capillary endothelia. There was no significant difference between the staining intensity of normal and inflamed pulp tissues. CD102 expression on the endothelium was significantly stronger in chronic periodontitis pulp samples. CD106, CD62-E, CD62-P, CD105, and CD54 were variably expressed in control and chronic periodontitis groups. Our results indicate that CD102 represents the major endothelial cell adhesion molecule probably involved in the inflammatory reactions in chronic periodontitis.

The effect of N-acetylcysteine and calcium hydroxide on TNF-α and TGF-β1 in lipopolysaccharide-activated macrophages

OBJECTIVE The present study was designed to evaluate the pro- and anti-inflammatory effects of NAC and calcium hydroxide (Ca(OH)2) on lipopolysaccharide-stimulated human macrophage cell lines. DESIGN THP-1 human monocyte precursor cells were differentiated into macrophage adherent cells. Cell cytotoxicity was measured by flow cytometry analysis. NAC and Ca(OH)2 were applied in the presence or absence of lipopolysaccharides (LPS) for time periods of 4, 8, and 24h. Protein and mRNA levels of tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta1 (TGF-β1) were determined using ELISA and qRT-PCR. The data were statistically analyzed by three-way ANOVA followed by Bonferroni test at α=0.05. RESULTS In LPS-stimulated cell lines, while the TNF-α protein and mRNA levels were reduced in the first 4h, only the TGF-β1 mRNA levels increased in the 24th hour following treatment with Ca(OH)2 and NAC when compared with the control group (p<0.001). In LPS-unstimulated cells, the TNF-α protein level was significantly decreased by NAC and Ca(OH)2 at the 4th hour. Additionally, while the TGF-β1 mRNA levels were significantly reduced, the protein level of TGF-β1 was increased at the 24th hour. CONCLUSIONS It was concluded that NAC, similar to Ca(OH)2, has anti-inflammatory properties and might be considered an alternate candidate therapeutical agent to Ca(OH)2.

The effect of calcitonin on osseous healing in guinea pig mandible.

Calcitonin (CT) is reported to be an effective medication for the treatment of inflammatory root resorption and to be capable of stimulating osteoblast proliferation in cell culture studies. In this study the effect of CT on the healing of osseous defects was evaluated in the mandibles of guinea pigs. After raising tissue flaps two experimental cavities were created on both sides of the corpus mandible of 33 guinea pigs. CT was applied into cavities either in hydroxypropyl methycellulose (HPMC) gel or gelatin as carrier. HPMC and gelatin alone and an empty cavity were also examined as control groups. Histopathological examinations under light microscopy were performed on weeks 1, 3, and 6. At week 1 in CT+gelatin and CT+HPMC groups, prominent osteoblastic activity was observed when compared with control groups. At week 3 the presence of woven bone in the experimental cavity areas reflected the increased osteoblastic activity in all groups. At the end of week 6 woven bone was gradually replaced by osteogenic tissue undergoing remodelization with Haversian systems in all groups. It is suggested that the osseous healing of the experimental cavity was enhanced by CT application in early stages (i.e. at week 1). However there was no significant difference of osteogenic activity between the control and CT-treated groups at the end of weeks 3 and 6.

Efficacy of rotary Ni-Ti retreatment systems in root canals filled with a new warm vertical compaction technique

The aim of this study was to compare the efficacy of Mtwo, ProTaper retreatment files and Hedström files for the retreatment of root canals filled with BeeFill 2 in1 and cold lateral compaction techniques. 63 single-rooted human teeth were prepared with Mtwo rotary files to size 35/.04 and assigned into three groups (n=21/group). (1) BeeFill 2 in1/2Seal, (2) BeeFill 2 in1/AH26 and (3) laterally-compacted gutta-percha/AH26. The specimens were subgrouped according to the file system used to remove root fillings (n=7/subgroup): 1. Mtwo retreatment file, 2. ProTaper retreatment file, 3. Hedström file. Roots were split longitudinally and photographed. The time required for removal of root canal fillings and the areas of residual root filling materials were compared statistically (p<0.05). The maximum amount of remnant was observed in the Mtwo group for removal of BeeFill 2 in1/AH26. ProTaper retreatment files required less time to remove root filling material than Mtwo retreatment files and Hedström files (p<0.05). Among the tested removal systems, ProTaper retreatment files may offer the best efficiency-speed combination.

Sealing Properties of Different Obturation Systems Applied over Apically Fractured Rotary Nickel–Titanium Files

This study investigated the sealing properties of cold laterally compacted gutta percha and Thermafil applied over different apically fractured rotary nickel-titanium files. Extracted human premolars were prepared by using ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland) or ProFile (Dentsply-Maillefer) systems (n = 40 for each), after which half of the specimens in each subgroup were subjected to instrument separation at the apical level. For each rotary system, roots with and without apically separated instruments (n = 10 for each) were filled with the two obturation systems and the levels of fluid conductance were recorded. In the absence of instrument separation, the leakage of Thermafil (Dentsply Maillefer) was significantly less than that achieved with cold lateral compaction (p < 0.05), whereas Thermafil yielded similar amounts of leakage in roots prepared with the ProTaper and ProFile systems (p < 0.05). Roots with fractured ProTaper instruments displayed significantly less leakage than those filled without ProTaper fragments, regardless of the obturation technique used (p < 0.05). However, intracanal separation of ProFile instruments increased the leakage (p < 0.05), but the obturation method did not influence fluid conduction (p > 0.05). These results reveal the variability of leakage associated with apically fractured ProFile and ProTaper files and different obturation methods used.

Influence of size and insertion depth of irrigation needle on debris extrusion and sealer penetration

Objectives To determine the effect of size and insertion depth of irrigation needle on the amount of apical extruded debris and the amount of penetration depth of sealer using a confocal laser scanning microscope (CLSM). Materials and Methods Twenty maxillary premolars were assigned to 2 groups (n = 10), according to the size of needle tip, 28 G or 30 G. Buccal roots of samples were irrigated with respective needle type inserted 1 mm short of the working length (WL), while palatal roots were irrigated with respective needle type inserted 3 mm short of the WL. Prepared teeth were removed from the pre-weighed Eppendorf tubes. Canals were filled with F3 gutta-percha cone and rhodamine B dye-labeled AH 26 sealer. Teeth were transversally sectioned at 1 and 3 mm levels from the apex and observed under a CLSM. Eppendorf tubes were incubated to evaporate the irrigant and were weighed again. The difference between pre- and post-weights was calculated, and statistical evaluation was performed. Results Inserting needles closer to the apex and using needles with wider diameters were associated with significantly more debris extrusion (p < 0.05). The position of needles and level of sections had statistically significant effects on sealer penetration depth (p < 0.05 for both). Conclusions Following preparation, inserting narrower needles compatible with the final apical diameter of the prepared root canal at 3 mm short of WL during final irrigation might prevent debris extrusion and improve sealer penetration in the apical third.