Fracture strength of mesiobuccal roots following canal preparation via hand and rotary instrumentation: An in vitro study

INTRODUCTION: The aim of this in vitro study was to compare the effect of hand and rotary instruments on fracture strength of tooth roots.MATERIALS & METHODS: Thirty two teeth were randomly divided into two experimental groups of 15 each and one negative control group with two samples. In group 1, step-back technique with conventional stainless steel K-files was used, and in group 2, instrumentation was performed using rotary Ni-Ti Hero642. Samples in control group did not received cleaning or shaping after access cavity preparation. After obturating each canal, tip of the spreader was locked within canal. The required force for root fracture was measured using Instron testing machine. Recorded data was statistically analyzed using t-test.RESULTS: The mean and standard deviation force required for vertical root fracture were 50.33±19.1 and 63.1±25.46 N for hand and rotary groups respectively. However, no significant difference was found between experimental groups.CONCLUSION: The results indicate that the manual technique did not lower fracture strength of obturated roots in comparison with the rotary preparation technique

Comparing coronal discoloration between AH26 and ZOE sealers

INTRODUCTION: Intrinsic tooth discolorations after endodontic treatment are principally attributed to the composition of necrotic pulp tissue, hemorrhage within the pulp cavity, endodontic medicaments and/or filling materials. Residual sealer left in pulp chamber after obturation can cause discoloration. The objective of this in vitro study was to evaluate coronal discoloration created by AH26 and ZOE sealers after four months. MATERIALS & METHODS: Fifty intact human extracted maxillary central incisors were employed. Access cavities were prepared in all samples and root canals were instrumented; coronal orifices were then sealed using self-cure glass ionomer. The teeth were divided into two experimental groups (n=20) according to utilized sealer in pulp chambers including AH26 and Dorifill (ZOE). The remaining 10 teeth served as negative and positive controls (n=5). The access cavities were sealed with self-cure glass ionomer. Teeth were kept in incubator for four month. Preliminary digital images of the teeth were taken and then compared with those related to 4-month follow-up. The images were assessed using Photoshop software. Data was analyzed using paired t-test and independent samples t-test. RESULTS: The teeth which were filled with AH26 sealer showed significantly greater discoloration than those filled with ZOE sealer (Dorifill) (P < 0.05). CONCLUSION: AH26 sealer causes greater discoloration of the crown compared to ZOE sealer. Despite the other disadvantage of AH26 sealer, it seems that Dorifill is more esthetically considerate

Odontogenic tumors in Iran, Isfahan: A study of 260 cases

Background: The aim of this study was to record the relative frequency of odontogenic tumors (OTs), evaluate and analyze the epidemiological features of the lesions in patients referring to dental faculty of Isfahan and compare these data with previous studies. Materials and Methods: In this study, we reviewed the records of 6,860 lesions from 1988 to 2010 archived in the oral pathology department of dental faculty of Isfahan retrospectively and using criteria for histological typification published by the WHO in 2005. Age, sex, site and extent of tumors were analyzed. Results: Among recorded lesions 260 were OTs (3.79%). Of these, 259 were benign and just 1 was malignant. The most common lesions were ameloblastomas ( n = 95) followed by odontomas ( n = 86), odontogenic myxomas ( n = 24) and others. There were a few more female patients ( n = 133, 51.15%) than male and the mean age of patients was 27.8 years (range 1.5-80 years). The posterior of mandible was the most common site ( n = 86, 33%). Conclusion: According to accumulated data, odontogenic tumors are uncommon lesions and malignant tumors are very rare

Comparative evaluation of Enterococcus faecalis counts in different tapers of rotary system and irrigation fluids: An ex vivo study

Background: Bacteria and their by-products are etiological factors for the failure of endodontic treatment. Reduction of root canal bacterial contamination is one of the chief aims of root canal therapy. The aim of this study was to compare the effects of different rotary file tapers and two irrigation fluids on Enterococcus faecalis counts. Materials and Methods: In this ex vivo study Root canals of 72 human upper lateral incisors were enlarged to ISO #20 K-file. Then, the samples were sterilized and inoculated with E. faecalis for 72 h, divided into six experimental groups and prepared with #30 Flexmaster files with 0.02, 0.04, and 0.06 tapers and two different irrigation solutions such as normal saline and sodium hypochlorite. The control group (n = 10) was subdivided into two groups with or without bacterial inoculation and no mechanical instrumentation. Cleaning efficacy was evaluated in terms of the reduction of colony forming units (CFUs). T-test, ANOVA, Duncan, and Tukey tests were applied to the groups. A significant level of α = 0.05 was set for comparison between the groups. Results: The canals instrumented with 0.06 taper exhibited greater significant reduction in CFUs compared to canals instrumented with 0.04 and 0.02 taper (P 0.05). Conclusion: Under the conditions of this study, root canal preparation with greater taper resulted in canal cleanliness and better debridement