Journal of Dental Medicine

Background and Aims: The need to use a highly effective sealer in order to create a complete seal along the canal is essential for the basic treatment of tooth roots. Therefore, the aim of this study was to investigate the sealing ability of cold ceramic and gutta-percha with sealer by applying the bacterial leakage and electrochemical method.
Materials and Methods: In this in-vitro experimental study, fifty human single-rooted teeth were selected and their crowns were cut from the cervical region. The canals were prepared and washed with 17% EDTA. Then the teeth were randomly divided into four groups: group 1 gutta-percha with AH26 sealer (Dentsply Detrey, Germany) (n=20), group 2 cold ceramic (Yazd, Iran) (n=20), negative and positive control groups which each consisted of 5 teeth. Samples were kept in an incubator at 37° C for 48 hrs. Two coats of nail polish were used for covering the root, except for the last 2 mm, and microleakage in the fillings was measured by the bacterial leakage and electrochemical methods. The microleakage of the two groups was statistically analyzed in the electrochemical technique by Student's t-test, and in the bacterial leakage method by Fisher's exact test.
Results: In bacterial leakage method, in the first group (gutta-percha) 7 samples (35%) and in the second group (cold ceramic) 3 samples (15%) had bacterial leakage, but no significant difference was observed between the two groups on different days (P>0.05). The mean microleakage based on the electrochemical technique in gutta-percha was significantly higher than that of cold ceramic (P=0.0001).
Conclusion: According to the lower microleakage values in the use of cold ceramic compared to gutta-percha, cold ceramic  can be used to fill root canals to reduce microleakage, although further studies are needed.

Background and Aims: Pulp necrosis in immature teeth disrupts root development and makes the teeth susceptible to fracture. Regenerative endodontics is a relatively new modality of treatment where the necrotic pulp is replaced with newly formed healthy tissue which has normal functionality. Many clinical reports have demonstrated the potential of this strategy to induce root maturation and apical closure. However, clinical outcomes are patient-dependent and unpredictable. Developing predictable protocols can be achieved through the interplay of three basic elements of tissue engineering, namely, scaffolds, stem cells, and signaling molecules. Furthermore, the clinical success of this treatment is influenced by both the method of preparing the inner space of the root and the type of biomaterial utilized in the coronal part. In this review, we discuss recent advances in tissue engineering-based strategies for regeneration of the pulp/dentine complex along with their advantages and limitations. 

Background and Aims: To be successful in root canal therapy, the dentists must be aware of the possible variation in the root canal and should know not only the natural anatomy of the pulp, but also a variety of possible morphologies. Frst of all, the dentists should be familiar with the possible anatomy of the root canal and then with the extraction of organic tissue from pulp chamber and root canal, increasing the chances of treatment success. Therefore, in this study, we decided to investigate the internal anatomy of root canals in the maxillary permanent molar teeth in Khoy city. Materials and Methods: In this in vitro study, 100 extracted human molars in Khoy city in West Azerbaijan province were collected. In all teeth, the access cavities were prepared, then they were decalcified and colored with India ink and evaluated by clearing technique. Data were collected based on Vertucci's classification which entered into SPSS23 software. The descriptive statistics in the form of numbers and percentages in tables and graphs were used to analyze the data. Results: The most common type observed in the mesiobuccal root of the first molars was type IV by 44%, in distobuccal root was type I by 92%, and in palatal root was type I by 94%. Also, in the mesiobuccal root of the second molars, the most common type was type I by 70%, in distobuccal root was type I by 94%, and in palatal root was type I by 96%. Conclusion: The mesiobuccal root of the first molar had the most variation in the internal anatomy. Also, the most common type of Vertucci in the mesiobuccal root of first molar was type IV and in the other roots of the first and second molar teeth was type I.

Background and Aims: The present investigation was conducted on the evaluation of the microstructure, phase transformation behavior, mechanical properties, and fatigue resistance of nickel-titanium rotary endodontic files. The main purpose of this investigation was to find the effect of microstructural parameters on the performance of these files.
Materials and Methods: Three rotary tools with brand names Denco, Edgeendo, and Eighteeth were studied. To evaluate the microstructure and transformation behavior of tools, metallography, X-ray diffraction, and differential scanning calorimetry methods were used. The bending test was used to check the behavior of superelasticity and memory and the microhardness test was used to evaluate the hardness of the samples. Also, cyclic fatigue behavior in a mold containing a simulated tooth canal was investigated and calculated by parametric statistical analysis. The fracture surface of the samples was also studied by scanning electron microscope.
Results: Analyses revealed the existence of a high volume fraction of R phase in the microstructure of the Edgeendo file. Rotary files with higher volume fraction of martensitic phase showed higher shape memory effect and fatigue resistance. Denco and Edgeendo rotary files with better surface quality and high volume fraction of martensitic phases in the microstructure showed better fatigue resistance compared with the Eighteeth file. In all the results, the P-value was less than 0.05.
Conclusion: Multiphase microstructure containing austenite and martensite together with appropriate phase transformation and hardness of the alloy have key roles on functional properties of rotary files. This study provides dentists with a deeper understanding of the fatigue behavior and mechanical properties of these files, enabling them to make more informed decisions in choosing the appropriate instruments for endodontic treatment.

Background and Aims: The foundations of a successful root canal treatment are adequate adaptation of the gutta-percha to the canal wall and the establishment of an impermeable apical seal. Despite the common use of M3 and Neoniti rotary files by dentists, no study has been conducted to examine the compliance of gutta-percha in curved canals prepared with M3 and Neoniti files using CBCT. The present study was designed and compiled with the aim of investigating the adaptation of gutta-percha in curved canals prepared with M3 and Neoniti files by CBCT.
Materials and Methods: This randomized controlled laboratory study was conducted ex vivo on 30 permanent human first molar teeth. The teeth were randomly divided into two groups (the first group with M3 and the second group with neoniti), after finding and fixing the appropriate canal path with the examined rotary files. All groups were filled with Single Cone method using F2 gutta-percha and AH26 sealer. Then, the gutta adaptation was assessed using clinical criteria (visual and radiographic) and after the specimens were evaluated using CBCT. All the images obtained from CBCT were converted into the JPEG format and then entered into image J software. The gap between the canal walls and gutta was measured in each canal, and the obtained data were analyzed using the Mann–Whitney U test.
Results: The results showed that the average and standard deviation of gap in M3 files (0.181 ± 0.089) was higher than that of Neoniti file (0.173 ± 0.033). However, no significant difference in the gutta-percha adaptation in curved canals prepared between the M3 and Neoniti files  was observed (P>0.05).
Conclusion: Considering the acceptable adaptation of gutta-percha in canals prepared with M3 and Neoniti files, the use of these two files is recommended in curved canals.