Iranian Endodontic Journal
Volume:3 Issue: 1, Winter 2008

The major objective in endodontic therapy is to disinfect the entire root canal system. This requires that the pulpal content be eliminated as sources of infection. This goal may be accomplished by mechanical instrumentation and chemical irrigation, in conjunction with medication of the root canal between treatment sessions. Microorganisms and their by-products are considered to be the major cause of pulpal and periradicular pathosis. In order to reduce or eliminate bacteria from the root canal system, various irrigants have been used during treatment. Chlorhexidine is a cationic solution which can be used during treatment. It has a wide range of antimicrobial activity. Furthermore, because of its cationic structure, chlorhexidine has a unique property named substantivity. The purpose of this paper is to review different aspects of chlorhexidine in endodontics.

The purpose of this study was to evaluate the number of distal roots and canals in mandibular first molars and their internal anatomy radiographically within Iranian population. A total of 310 distal roots of mandibular first molars were incorporated in this study and evaluated in terms of number of roots and number and types of canals. Root canal systems were studied in vitro by means of radiography and based on Vertucci’s classifications. It was shown that 4.5% of the teeth in this study had two distal roots, of which, 100% indicated type I for both distobuccal and distolingual roots. Among all the teeth, 43.2% had two canals, 24.2% two apical foramina, and 38.7% two orifices in their distal roots. According to Vertucci’s classification 54.9% of the teeth were type I, 19% type II, 1.9% type III, 14.2% type IV, 4.2% type V, 1% type VI, 0.3% type VII and 0% type VIII. In as many as 43.2% of all teeth assessed in this study, bicanaled distal roots were observed, dentists are always recommended to search for the second canal in distal roots of mandibular first molars. In case the second canal in the distal root is missed, failure of endodontic treatment will be anticipated. A rectangular type access cavity design allows better visualization and negotiation of the probable second canals within the distal roots of mandibular first molars.

The purpose of this study was to compare first accessory gutta-percha penetration after the use of nickel-titanium (Ni-Ti) or stainless-steel spreaders in curved resin blocks. Forty resin blocks with 30º and 45º curvatures (20 blocks for each) were prepared and #30 master cones were placed in canals. In part one, under 20 Newton pressure, Ni-Ti or stainless-steel spreaders were placed alongside the master cone and their penetration was measured with a millimeter ruler. In part two, after removing the spreader, one of the accessory cones (#15, #20 or MF) was substituted in the canal and its penetration was measured. The Mann-U Whitney test was used for the final evaluation. In both curvatures, the penetration of Ni-Ti spreaders were significantly more than stainless-steel spreaders(p≤0.005).Penetration of the first accessory cones (#15 and MF) in Ni-Ti spreader group were also significantly more than stainless-steel group (p≤0.05) (in both curvature groups). This study showed that Ni-Ti spreaders and #15 accessory cones penetrated deeper in curved canals than stainless spreaders and #15 accessory cones. Therefore, the use of NiTi spreader in lateral condensation technique is suggested for better results.

General dental practitioners provide the majority of treatment in Iran. The aim of this study was to gather information on the methods, materials and attitudes employed in root canal treatment by dentists participated in 7th Congress of Iranian Academy of Restorative Dentistry in Shiraz /2007 in order to evaluate the quality of current practice. A questionnaire for this cross-sectional study was designed with the purpose of evaluating the routine endodontic treatment performed by Iranian dentists. The questionnaire made up of 24 questions with multiple-choice answers. Covering subjects are demographic and professional activity, root-canal preparation and instrumentation, choice of irrigants and disinfectants, and choice of obturation techniques. A total of 247 questionnaires (49.4%) were returned. Ninety-one percent of the respondents were general dental practitioners. The results indicate that there are discrepancies between daily practice and academic teaching, especially regarding the use of rubber dam (only 0.9 % report using it as a standard procedure). Most of practitioners used manual instruments manipulated with a filing technique and few used rotary for canal preparation. The majority of the respondents prepared root canals 0.5-1 mm short of the radiographic apex. The first-choice root-canal irrigant was normal saline (55%), followed by sodium hypochlorite. Approximately, 68% used intracanal medications. The most popular obturation technique was cold lateral condensation (90%) with zinc-oxide eugenol as sealer. Most practitioners performed treatment in two visits for teeth with two or more canals. Eighty-four percent of the dentists used radiograph for determining the working length, and only 2.7% used Apex-locator. The survey mentions the importance of continuing dental education for practitioners to update their knowledge.

A variety of mesial and distal projections have been suggested for separating the canals in a multi-canaled root. But there is no general agreement on the best angulation for each tooth. The purpose of this study was to evaluate the X-ray horizontal angle for separating the canals of four-canal first mandibular molars. Forty four-canaled mandibular molars were selected. After preparation of coronal access cavities, files were inserted into the root canals and the specimens were radiographed at 10, 15, 20, 25 degrees mesial and distal horizontal angulations. Apices and canals were evaluated. Chi-square test was used for statistical analysis Although 10° and 15° mesial and distal angulations were best for the most obvious apices manifestation (p≤0.001)it was found that 20° mesial angulation is significantly better than the other cone angulations (p ≤0.001)for separating the root canals. 20° mesial angulation improved detection of both the canals and canal terminus visibility

Knowledge of the anatomic location and dimension of the molar pulp chamber may preserve healthy pulp during operative procedure and reduce risk of perforation of chamber during access preparation. A review of literatures regarding the morphology of pulp chamber however revealed very little information; so the aim of this in vivo study was to measure the dimensions of first molar pulp chambers as seen on bitewing (BW) radiographs. In this cross-sectional study molar''s BW radiographs of 130 subjects in two age groups were taken under standardized conditions (group of 18-25 years old subjects and group of 50-65 years old subjects). The films were digitized and nine anatomical landmarks were evaluated from the image of each first molar as follow: A; mesial to distal pulp horn distance, B; mesial to distal walls at the middle of pulp chamber, C; mesial to distal orifices, D; mesial cusp tip to its horn, E; distal cusp tip to its horn, F; pulp chamber height, G; pulp chamber floor to furcation, H; pulp chamber ceiling to furcation, I; cusp tips to furcation. The data were evaluated by using AUTOCAD (2007) software with 0.00 precision. Two way ANOVA test (Uni-variant analysis) were used to determine the interaction between restoration and age on pulp chamber dimensions. There was no significant difference in pulp chamber dimensions between the genders. Although there was significant reduction in the size of pulp chamber with advancing age, no significant differences were found in the restored and non restored teeth. The finding of this study showed size reduction and changes of pulp chamber with age so may enhance knowledge to minimize errors during endodontics treatments.

The aim of this innovative study was to regenerate a condition that makes it possible to carry out researches in the field on a variety of resorption. In order to develop apical resorption, the root canals of selected teeth were instrumented and then drilled with #4 Gates Glidden drills. In the next stage, the teeth were submerged in melted rose wax up to 3 mm to the apex. The waxed teeth were submerged in 20% sulfuric acid for 4 days. After that, all samples were evaluated under stereomicroscope and also the SEM. Images showed areas with different pattern of resorption in root apex and entire root canals in all samples. Simulation of the root resorption can be helpful in many experimental studies.

Chronic hyperplastic pulpitis (pulp polyps) usually occurs in molar teeth of children and young adults and is characterized by an overgrowth of granulomatous tissue into the carious cavity. Here, we report a rare type of pulp polyp in lower third molar of a 27-year-old woman that not only grow into carious cavity but also extruded in very large size that interfered with occluding of the teeth.

The purpose of this study was to compare the apical sealing ability of lateral and vertical compaction techniques following immediate and delayed post space preparation. Seventy-four distal and palatal roots of human extracted molars were instrumented and randomly divided into 4 experimental groups (n=15), two experimental control groups (n=5), and two positive and negative leakage controls (n=2). Canals were filled by lateral (groups 1 and 2) and vertical (groups 3 and 4) compaction techniques using Tubliseal sealer. Post space was prepared immediately after obturation in group 1 and after seven days in groups 2 and 4 using a # 3 Peeso drill. In group 3, post space was prepared immediately during down-packing phase. The teeth were kept in 2% methylen blue dye for seven days. The roots were sectioned buccolingually and the mean score of dye penetration was measured. Data was analyzed with T-test and one way ANOVA. There was significant difference in dye penetration between delayed and control-lateral compaction groups (p=0.009). There was also a significant difference in dye penetration between immediate and delayed lateral compaction groups (p=0.044). Less apical leakage in the cold lateral condensation and immediate post space preparation group was observed.