Journal of Dental Medicine

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Statement of Problem: Root canal cleaning and shaping are important steps in endodontic therapy. In order to develop better techniques, new instruments are constantly designed and delivered to the market.
Purpose: The aim of the present study was to compare the effectiveness of one manual with three rotary root canal instrumentations techniques.
Materials and Methods: In this in-vitro study, 80 mesial roots of freshly extracted human mandibular molars were divided in to four groups equally and prepared by one of the following instrumentation methods profile NiTi rotary system, Protaper NiTi rotary system, Flex Master NiTi rotary system and hand NiTi K-file instrumentation. In each root one of the canals was instrumented and the other was used as control.After decalcification, cross sections at 3mm and 5mm of apical portion were prepared and examined for remaining debris, predentin and smooth walls under light microscope. The data were analyzed by Kxuskal-Wallis test.
Results: Significantly less debris was found at 3mm cross- section using protaper and Flex Master techniques (P<0.05). No significant differences were found at 5mm cross section. Also no significant differences were observed for remaining predentin at all regions. Significantly more smooth walls were found at both regions using protaper technique (P<0.05).
Conclusion: The protaper technique employed in this study resulted in cleaner root cana! walls than the
other techniques.

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Statement of Problem: Total removal of tissues and remnant microorganisms as well as canal shaping are the essential objectives of endodontic therapy. A successful endodontic treatment is obtained through Shilder’s principals, however complete observation of this technique using stainless steel files manually is problematic and time-consuming. Modern technology, in order to eliminate such problems, has presented new facilities such as Nickel-Titanium (NiTi) files and engine driven instruments.

Purpose: The aim of this in-vitro study was to compare the canal debridement efficiency of three engine driven instruments: Rotary, Reciprocal and Vertical.

Materials and Methods: In this experimental study, 60 mesial roots of human first and second mandibular molars were divided into three groups randomly. In each sample, one canal was considered as case, the other one as control. Files used in Reciprocal and vertical groups were of handy Ni-Ti type and in rotary group, rotary Ni-Ti files were used. After debridement, the roots were sectioned at 3mm and 5mm from anatomic apex, stained and examined under light microscope. Comparison criteria between case and control groups were based on residual debris and predentin and the level of root canal preparation and shaping after debridement. Data were subjected to kruskal-Wallis non-parametric test.

Results: There was no significant difference between the efficiency of debridement at 3mm and 5mm sections between all groups. But difference in time consumption was significant ranked from the shortest to the longest as rotary, reciprocal and vertical.

Conclusion: The efficiency of debridement between the three automated instruments was approximately equal, however the instrumentation time was different between three groups. Rotary system was the fastest one, as compared with reciprocal (second) and vertical (last). It may be concluded that rotary system has a superiority over the other two groups in conventional root canal therapies.

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Statement of Problem: Today, cross infection control is an integral part of dentistry and many dental health care workers no longer question its necessity. All dental equipments and instruments could be potentially considered as a source of infection.

Purpose: The aim of this study was the evaluation of aerobic contaminations of four disposable materials used in routine dental practice.

Materials and Methods: In this cross-sectional study, random sampling was performed and tryptone soy broth transfer culture medium was used. After 24 hours of incubation, samples were transferred to specific culture media. (Mckangy, Chocolate agar and Blood agar). Cultured bacteria were stained and studied using gram staining method. The study was carried out in a 17 weeks period.

Results: All suction tips were infected with Bacillus cereus bacterium. Two cases of cotton roll samples showed contamination with Bacillus cereus, 2 cases with gram positive, coagulase negative cocci, 1 case with Streptococcus viridians and one case with Enterobacter class A. One case of anesthetic cartridges was contaminated with Staphylococcus epidermidis and two cases with Streptococcus viridians. Two cases of gutta-percha samples were contaminated with Bacillus cereus.

Conclusion: Based of the findings of this study, the highest level of contamination was observed in saliva ejector tips. Contamination with Bacillus cereus was seen more frequently.