Evaluation of Radicular Dentin Thickness of Danger Zone in Mandibular First Molars

Objective: Better understanding of the furcation anatomy may serve to decrease the risk of root perforation. The purpose of this study was to measure the thickness of root walls in the danger zone in mandibular first molars.Materials and Methods: The roots of 53 extracted human mandibular first molars were sectioned in the horizontal plane 4 mm below the orifice of the mesial and distal root canals.For each cut surface buccal, lingual, mesial, and distal thickness of the root wall wasmeasured. Mean values of the thickness at each location were calculated and compared by ANOVA and t-test.Results: The results showed that the mean thickness in the distal portion of the mesial root was smaller in comparison to all other portions of the roots (P<0.05) and this difference was statistically significant except for the mesial portion of the distal root (P=0.463). The mean thickness of radicular dentin at the distal aspect of mesial roots was 1.2 millimeter.Conclusion: Our study suggests that knowledge of the root dentin thickness in the danger zone is essential for preventing endodontic mishaps leading to failure

Comparison of different techniques for disinfection of teeth internal space in preclinical teaching

&quot;nBackground and Aim: Extracted teeth used in preclinic should be disinfected. The aim of this study was to evaluate the effects of some disinfectants on microorganisms cultured from pulp chamber of extracted teeth.&quot;nMaterials and Methods: In this experimental study 54 intact human teeth were collected. After access cavity preparation, 10 8 B. streothermophillus endospors were inoculated into pulp chamber. Then cavities were sealed with a temporary restorative material. Teeth were divided into 5 groups of 10 each. The teeth were then stored in these disinfectants: 5.25% hypochlorite sodium, 5% Microten, 5% Deconex, 2% Glutaraldehyd, and 10% Formalin for 48 hours. Two teeth were autoclaved as negative controls and two were stored in normal saline as positive controls. The teeth were then sectioned in cervical area and cultured in Trypticase Soy Broth. After three days turbidity in tubes was evaluated. Statistical analysis was done by Fisher&apos;s exact test.&quot;nResults: None of these solutions were able to prevent microorganism growth in all samples; however, Formalin was better in six cases than that of other disinfectants. Differences between these five groups were not statistically significant (P=0.384).&quot;nConclusion: Sterilization of the teeth with autoclave is the only absolute method for disinfecting the root canals of extracted teeth and disinfectants are not reliable for this purpose

In Vitro Comparison of Instrumentation Time and Cleaning Capacity between Rotary and Manual Preparation Techniques in Primary Anterior Teeth

Objective: The aim of this study was to evaluate and compare the cleaning ability and instrumentation time of manual and rotary methods used for preparation of primary an-terior teeth.Materials and Methods: Forty-four primary anterior teeth were used in this experi-mental study. Access cavities were prepared and India ink was injected into the canals. The samples were divided into three groups according to the instrument and preparation technique. In group I the root canals were manually instrumented with K-files. Rotary Flexmaster instruments were used for canal preparation in Group II, and the samples in Group III (control) were not instrumented. After canal preparation, the teeth were cleared with methyl salicilate and the removal of India ink was measured in the cervical, middle and apical thirds. The incidence of file breakage and instrumentation time was recorded in the three study groups. Statistical analysis was performed using Mann-Whitney and t-tests.Results: There was no significant difference in cleaning capacity between the two tech-niques, but a significant difference was found between the experimental and control groups. Working time was significantly shorter when using the rotary system. No file fracture was observed during the study period.Conclusion: Regarding the shorter working time for rotary instrumentation and the similar cleaning ability of the two techniques, the application of the rotary system is suggested for preparation of decidious root canals during pulpectomy

Comparison of the apical leakage of root canals filled with MTA with those filled with gutta percha and lateral condensation technique

Background and Aim: Sealing the root canal system is of great importance in endodontic treatment especially in infected teeth. Several materials have been introduced for this purpose. The aim of the present study was to evaluate the sealing ability of MTA as an orthograde root filling material and compare it with laterally condensed gutta-percha with sealer.Materials and Methods: Thirty-six extracted human maxillary central and canine teeth were used in this experimental study. After preparation and surface disinfection with 1% NaOCl solution, the crowns of the teeth were cut at cemento-enamel junction.Roots were randomly divided into four groups: two experimental groups &amp;nbsp;of 15 roots each (gutta-percha with AH26 sealer and MTA) and two control groups of 3 roots each (positive and negative). After root canal preparation and filling, the sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 72 hours. Then the teeth were cleared and the extent of dye penetration was measured with a stereomicroscope. Data were analyzed by T-test with P&amp;lt;0.05 as the level of significance.Results: The results showed that the mean microleakage was 1.1mm (SD=2.1) in the gutta percha group and 3.4mm (SD= 2.1) in the MTA group.This difference was statistically significant (P=0.013).Conclusion: Based on the results of this study, canal obturation with gutta-percha and AH26 sealer may provide a better apical seal compared with MTA. However, further studies on microbial leakage are needed for more precise evaluation of the sealing ability of MTA

In vitro comparison of microbial microleakage of two types of MTA (Made in Iran and Brazil) used in single visit apexification

Background and Aim: Incomplete root development caused by trauma ,caries, or pulpal pathosis requires special attention and treatment . Although calcium hydroxide apexification has been used successfully for years but it requires patient cooperation and multiple appointments . Single visit apexification with MTA has been used in recent years. The purpose of this study was to compare bacterial microleakage of two types of MTA (Made in Iran and Brazil) applied as apical barrier in open apex teeth.Materials and Methods: 48 single root teeth were used in this experimental in vitro study. Teeth apices were prepared as open apex teeth. For canal obturation the 4mm of root end was filled with 2 types of MTA (white Iranian MTA salami co. Iran and Angelus MTA Angelus Brazil) from coronal access. Teeth were mounted in self-cured acryl and put in BHI microbial culture. A suspension of Staphylococcus epidermidis was injected from coronal area into the root canals.The teeth were incubated and examined every 24 hours for microbial microleakage, indicated as turbidity in culture. Data were analyzed using Fisher exact test with p&amp;lt;0.05 as the level of significance.Results: Microleakage appeared after 15 days in all Iranian and after 17 days in Angelus MTA samples.There was no significant difference between microleakage of two types of MTA (P = 0.48).Conclusion: Based on the results of this study, there was no significant difference between microleakage of Iranian and Angelus MTA. If further studies confirm other physical, chemical, biological and sealing properties of Iranian MTA, it could be recommended for clinical applicatio

The Effect of Canal Contamination with Saliva on Apical Sealing

Introduction: Root canal obturation aims at sealing the root canal system to prevent re-contamination of canal and periapical space. Presence of moisture in canal before obturation may posit a negative effect on the quality of canal sealing. Therefore, this study was conducted to investigate the effect of canal contamination with saliva on apical microleakage. Methods: In this laboratory study, 58 human uni-root teeth were cleaned and shaped for obturation with gutta percha and sealer AH26. In the case group, specimens were contaminated with human saliva immediately before obturation, whereas the teeth in the control group were kept dry. All canals were filled by lateral condensation technique. Moreover, the teeth were placed in methylene blue dye for 3 days. Dye penetration was measured using a stereomicrosope. As a matter of fact, the study data were analyzed via utilizing t-test. Results: A significant difference was found between the two groups in regard with the apical leakage(P<0.001). The microleakage mean of dye in the dry group was 3/48mm, whereas it was 6/36mm in the saliva contaminated group. Conclusion: The study findings revealed that complete drying of canal can improve apical sealing