Iranian Endodontic Journal
Volume:7 Issue: 2, Spring 2012

Based on Iran’s 20-year prospective national vision document, Iran may be seen as the most developed country in science and technology in the region by 2025. In this report, bibliometric indicators are used to compare the research productivity in endodontics between Iran and 28 selected Asian countries. Medical Subject Headings keyword-searching of PubMed up to 2012 was conducted to compare the scientific publications in Iran and neighboring countries (Middle East, Middle Asia, Caucasus and EMRO countries). Highest 5 PubMed-indexed endodontic journals were also searched to retrieve the number of published articles of the top five countries. Data were extracted, tabulated and compared to identify the ranks as well as trends. The results confirm that there are many differences in scientific endodontic publications between the studied countries; Iran ranked second in endodontic research productivity compared to Turkey in 2011. However, Iran attained first place in 2010 as well as the most positive publication trend in PubMed-indexed endodontic journals. Although Iran was in second rank in the region last year, the positive trend in published endodontic research papers is considered a sign of future success in acquiring Iran’s vision.

Formocresol is widely used in primary teeth pulpotomies; however it is known to have several side effects. The purpose of this study was to assess pulpal changes of primary teeth pulps after pulpotomy with sodium hypochlorite and formocresol. In this randomized clinical trial, 22 teeth were selected. These teeth were randomly divided into 2 groups (formocresol; n=11 and sodium hypochlorite n=11). Two months post-operatively teeth were extracted and pulpal responses were evaluated by recording the degree of inflammation and extent of pulpal involvement. Dentinal bridge formation was also evaluated. Finally the data was analyzed with McNemartest. The formocresol group demonstrated mild inflammation in 4 cases whereas sodium hypochlorite had mild inflammation in six cases. Severe inflammation was only found in 1 case in the sodium hypochlorite group, but it was present in 4 cases in the formocresol group. In sodium hypochlorite group there were no cases of necrosis, and dentinal bridge was found in 3 cases, unlike, the formocresol group which had necrosis but no dentinal bridge formation. Based on the results of this study sodium hypochlorite may be a suitable solution for conducting pulpotomy in primary teeth.

The purpose of this study was to compare the inhibitory effect of heat-killed Candida albicans and dentin powder on the antibacterial activity of chlorhexidine (CHX) against Enterococcus faecalis and Streptococcus sanguis. The antibacterial effect of each group was determined by measuring the zone of inhibition diameter in millimeters after incubation at 37°C for 24 hours in a humid atmosphere. Each test was repeated three times. Data were analyzed using ANOVA and Tukey’s test. Results indicated that both heat-killed C. albicans and dentin powder decreased the antibacterial activity of CHX against both tested bacteria significantly (P<0.05). In conclusion, both heat-killed Candida albicans and dentin powder reduced the antibacterial activity of CHX significantly.

Some studies in dental literature have proposed that short term and long term exposure of root dentin to calcium hydroxide predisposes it to fracture. Mineral trioxide aggregate (MTA) and a recently introduced endodontic material, calcium-enriched mixture (CEM) cement may be used instead of calcium hydroxide and might have an effect on the strength of root dentin. Therefore, the aim of this in vitro study was to compare the short-term effect of calcium hydroxide, MTA and CEM cement on the strength of bovine root dentin. In this experimental study, 15 freshly extracted intact bovine incisors were selected. A cylinder with uniform wall thickness (internal diameter of 2.5 and external diameter of 5.5) was prepared. The cylinders were cut longitudinally into 4 symmetrical pieces. The 60 prepared samples were divided into four groups (n =15). The samples were placed in 4 petri-dishes containing calcium hydroxide, MTA, CEM cement and normal saline as the control group. They were then subjected to flexural forces applied by Instron universal machine. Data was analyzed using ANOVA and Tukey test. The mean flexural force in the calcium hydroxide, MTA and CEM cement groups was significantly lower than that in the control teeth (77.9 N, 90.66 N, 94.40 N, compared to 125.12 N respectively, P=0.001). There were no significant differences between calcium hydroxide, MTA and CEM cement group. MTA and CEM cement decreased the flexural strength of bovine root dentin, like their counterpart calcium hydroxide. Further studies are required to determine the effect of these materials on human root dentin clinically.

Good radiographs are required for endodontic therapy and because some patient’s are intolerant to intraoral films and/or sensors, this can cause complications in endodontic treatment. Extraoral film placement can be used to obtain clinically diagnostic and working radiographs. The no. 2 receptor was placed against the model’s cheek and centered in the molar-premolar area. The central beam was directed toward this area from the opposite side. The vertical and horizontal angles that achieved the most accurate radiograph were calculated by trial and error. The best method equated with the patient sitting upright and the Frankfort plane being horizontal to the floor and when the head was tilted 10 degrees toward the side being examined. For the upper posterior teeth the center of the image receptor was placed on the intersection of the ala-tragus and a parasagittal line while the upper border of receptor was parallel to the canthomeatal line; the cone was positioned a negative 25 degrees from the horizontal plane. The central beam was directed from midway between maxillary and mandibular premolars and molars of the opposite side. For the lower posterior teeth, the receptor was placed against the cheek on the side of interest and its lower border was parallel and 2 cm above the inferior border of the mandible. The cone was angled -20 degrees from the horizontal plane while the central beam was directed towards the mandibular molar-premolar region 1 cm below the lower border of the mandibular of the contralateral premolar/molar region. Using this novel technique, high quality images can be acquired for patients who cannot tolerate intraoral radiographs.

The main goal of this ex vivo study was to assess and compare the cellular and electrophysiological effects of two dental biomaterials, white mineral trioxide aggregate (WMTA) and calcium enriched mixture (CEM) cement, on neuronal cell excitability and electrical properties. A conventional intracellular current clamp technique was used to study the cellular effects of WMTA and CEM on the excitability, firing and the shape of action potential of neuronal soma membrane of F1 nerve cells. The dental biomaterials were prepared according to the manufacturer's directions and were applied to the bathing media and 0.05 mL of total mixture of each dental material at a distance of 3 mm from the cells. Findings indicated that exposure to both dental biomaterials shifted the irregular high frequency firing type observed in control conditions to a more regular low frequency firing pattern. Neuronal exposure to WMTA, but not CEM, significantly hyperpolarized the cell resting membrane potential. Both treatments significantly influenced the duration and the amplitude of action potentials. Extracellular application of either CEM or WMTA caused a significant increase in the after hyperpolarization (AHP) amplitu de and AHP area, but the potentiating effect of WMTA was more effective than CEM. Treatment with WMTA or CEM resulted in a profound alteration in the firing behaviour of F1 cells and changed the AP characteristics. Both dental biomaterials reduced the neuronal activity possibly through enhancement of K+ outward current. This may possibly explain the positive mechanisms of these biomaterials in regenerative endodontics, though further research is needed for such a conclusion.

The purpose of this study was to determine the effects of citrus aurantifolia (CA) extract on smear layer removal in different parts of root canals. Thirty-nine single-rooted human teeth were randomly divided into three experimental (n=12) and one control (n=3) groups. Teeth were instrumented using MTwo rotary instruments. Root canals were irrigated with NaOCl during instrumentation. The canals in each group were irrigated with one of the following: completed mixture of citrus aurantifolia extracts, 17% EDTA, and alcoholic extract of CA. Distilled water was used for the control group. The irrigants were left within the canal for 20 minutes, and then rinsed with normal saline solution. Teeth were subsequently split longitudinally into 2 halves, and the canals were examined by a scanning electron-microscope. Cleanliness was evaluated using a five point scoring system. Statistical significant difference was found between groups (P<0.05). The smear layer was more effectively removed with 17% EDTA compared to alcoholic CA extract. However, they were both able to remove the smear layer in the coronal segment. Completed CA extract removed more smear layer in coronal and middle parts compared with the alcoholic extract (P=0.001); however, there was no significant difference in the apical part. Both of the alcoholic and completed mixtures of citrus aurantifolia extracts were not able to effectively remove smear layer compared with 17% EDTA during root canal therapy.

Cone-beam computed tomography (CBCT) has been accepted as a useful tool for diagnosis and treatment in endodontics. Despite a growing trend toward using CBCT in endodontic practice the CBCT images should be interpreted carefully. This case report presents a case that showed radiolucency inside and around a tooth which was free of pathologic changes under a dental operative microscope and conventional radiographs. A male patient was referred to an endodontic office for evaluation of radiolucency inside and around tooth #21 in his CBCT images. The post and crown over the tooth was removed and the tooth was observed under a dental operative microscope. Clinical examination as well as direct observation under a dental operative microscope showed no pathological lesions inside and around the tooth. The misdiagnosis was based on an artifact on CBCT. Despite the advantages of CBCT images as a great radiographic aid in endodontic practice, in the presence of metallic structures such as post and core the images should be interpreted with caution.

Premixed non-setting calcium hydroxide (CaOH2) paste in pressure syringe system is commonly used in root canal therapy. The aim of this paper is to present a case involving an iatrogenic extrusion of the medicament during endodontic treatment and a literature review of similar reports. The present case demonstrates severe tissue necrosis and other deleterious effects following the extrusion of CaOH2 paste beyond root apex. A 21-year old female was referred for endodontic treatment of her maxillary left first premolar. After completion of the canal preparation, root canals were filled by premixed CaOH2 paste. In the second appointment, a gingival detachment and an irregular zone of necrosis adjacent to the tooth apex was observed. To treat this complication, a mucoperiosteal flap was raised and the extruded material and necrotic tissues were currettaged and the area sutured. The patient was prescribed antibiotics and followed up at 2 weeks, 6 months and 2 years. Two week follow up showed good soft tissue healing. Two years postoperatively, complete radiographic and clinical healing was observed. We can conclude that the application of CaOH2 should be carried out with care and preferably applied free hand or with a lentulo spiral rather than in a pressure syringe.