Comparing the dental root biomechanical properties following two different methods of instrumentation and obturation

Clinically, vertical root fracture occurs commonly in endodonttcaliy treated teeth. Previous studies have shown little changes in root fracture strength following endodontic treatment. The purpose of this study was evaluation of changes in dental root biomechanical properties following two different methods of instrumention by Rotary [R] or Hand [H] files and two different methods of obturation by lateral [L] or vertical [V] technique. In this invitro study, one hundred extracted human mandibular premolars with straight root, closed apices and free of caries were selected. For the teeth to be indentical and simple to study, all teeth were decoronated 3mm above the CEJ. With making artificial PDL, all teeth were mounted in acrylic molds. Teeth were randomly distributed into four experimental groups according to the instrumentation and obturation techniques used each with a sample size of 25. Hand instrumentation was done using stainless steel [S.S] files and Step-Back technique. Rotary instrumentation was done using Ni-Ti files [Race] and crown-down technique. Loading was applied using a crosshead conical tip mounted in an Zwick testing machine. The crosshead tip was initially placed into the canal orifice of each tooth, advanced vertically until it contacted the gutta-percha automatically and at a constant rate [2mm/min]. Root fracture was noted with observation of a sudden deflection in the running graph. Load to fracture was recorded in Newton [N]. The energy to fracture, slope of elastic area and displacement was calculated using origin V.5.Q software through running graphs. The data were analyzed using ANOVA and Duncan test. Maximum mean load to fracture was observed in RL group [524 N]. Minimum mean load to fracture was observed in RV [Rotary and Vertical] group [319 N]. A significant difference in mean load to fracture was found between the [Rotary and Vertical] RV and [Hand and Lateral] HL, [Hand and Vertical] HV and [Rotary and Lateral] RL and [Rotary and Lateral] RL and [Rotary and Vertical] RV groups [P<0.05]. Both the energy and displacement were significantly correlated with load to fracture. The fracture strength of roots obturated through vertical compaction of gutta-percha was lower than that of lateral compaction regardless of method of instrumentation. Fracture strength of root was not affected by the method of instrumentation [hand or rotary]

[Comparing two different sealer penetrations in dentinal tubules and apical microleakage after using MTAD as a final irrigant]

The effect of removal of smear layer has already been a subject in many investigations, and has been a matter of controversy. Of course there is no doubt that sealer penetration would be facilitated when smear layer removed. The aim of this study was evaluation of the relationship between sealer penetration and apical microleakage after usage of MTAD. In this invitro study, 135 human single root extracted teeth were selected. The teeth were divided into three groups [40 samples in each] as experimental groups as follow: Group 1: Serum was used for irrigation [with the smear layer]. Group 2: EDTA 17% was used for irrigation [removal of the smear layer]. Group 3: MTAD was used for irrigation [removal of the smear layer] and 15 teeth were considered as the control. The teeth in each group were divided into two subgroups [20 teeth] to be filled either with AH Plus or Dorifill sealer. Sixty teeth were selected for dye penetration with methylene blue and statistically analysed using One-Way and Two-Way ANOVA. In the other 60 teeth, sealer penetration was evaluated using SEM. The data were statistically analysed using Kruskal-Wallis and Mann-Whitney tests. The end relationship between dye penetration and sealer penetration was evaluated by spearman correlation test. There was no significant difference between the three types of irrigants. There was a significant difference between the two sealers. AH plus revealed less dye penetration. Minimum dye penetration was observed in MTAD group with AH Plus and maximum dye penetration was observed in Serum group with Dorifill. Sealer penetration in MTAD and EDTA groups were better than Serum group. AH Plus was better than Dorifill. The correlation between sealer penetration in dentinal tubules and dye penetration wasn't statistically significant. Type of irrigant didn't affect apical microleakage but type of sealer affected microleakage. AH Plus proved to be better. AH Plus showed greater sealer penetration. Greater sealer penetration does not necessarily reduce apical microleakage

[Double maxillary central incisors: a case report]

Fusion and Gemination are developmental anomalies of the dental hard tissue. The preferred terminology for these two abnormalities is [double teeth]. A 10 year-old boy presented with a [double] maxillary permanent left central incisor. In clinical and radiographic examination, a large crown with two distinguishable roots and pulp spaces was observed. Double teeth usually need a multidisciplinary approach. Because of the communication found between the pulp spaces, endodontic treatment was performed followed by periodontal surgery to remove one of the roots and its corresponding crown. Finally, restorative and orthodontic treatment was provided

[ case report; endodontic treatment of 4-rooted mandibular second molar tooth]

The knowledge of root canal anatomy and morphology and understanding the cases with variations from the normal anatomy are necessary to achieve success in endodontics. No cases with four separate roots in the mandibular second molars have been reported sofar. The purpose of this study was to report the presence of four separate roots in a mandibular second molar in a patient. A 29 year old male patient was referred for root canal therapy of a mandibular right second molar with a history of emergency treatment. The diagnostic radiograph revealed the presence of four separate roots. The presence of five orifices was confirmed in the pulp chamber after access cavity completion. Conventional root canal treatment was performed in the five root canals of the tooth. The knowledge of common anatomic configurations and possible variations in root canal morphology is one of the important factors for a successful root canal treatment. Report of uncommon cases can motivate the dentist to always perform exact radiographic and clinical evaluations of the teeth and consider the rarities during root canal treatment

[Effect of obturation techniques on obturation quality of molar C-shaped canals]

Due to the anatomic complextieis of C-shaped canals, using an obturation technique capable of filling the irregular isthmus in the root canal system seems to be necessary. The aim of this study was to compare the efficacy of three different root canal obturation techniques used for filling the irregular root canal system in C-shaped teeth. The study was perfomed on 30 human extracted molar teeth which were radiographically and anatomically recognized as having C-shaped canals. All root canals were prepared in the same way and the samples were divided into 3 groups, each of 10 teeth. The root canals in group I were filled by cold lateral condensation technique [CL]. Teeth in group II were filled by means of warm lateral condensation technique [WL] and those in group III were filled by means of warm vertical condensation technique [WV]. All teeth were demineralized and then cleared with methylsalicilate. Images were taken from both longitudinal and cross-sectional feature of the cleared teeth by a digital camera connected to a stereomicroscope. The filling quality of the main canals and the isthmus between them was evaluated by three independent endodontists. The data were statistically analyzed by chisquare, one way and two way ANOVA and t-test. In longitudinal photographs, the highest percentage of good filling quality [80%] was observed in the WV group and was significantly more acceptable than WL group [p<0.05]. The lowest percentage of good filling quality was observed in the isthmus area of the canals [46.7%] which was significantly less than other areas [p<0.05]. Cross- sectional photographs demonstrated no significant difference between the percentage of isthmuses filled with the filling material and the two areas of the canals in the three obturation techniques [p>0.05]. The results indicated that none of the suggested techniques could successfully fill the root canal space, but the warm vertical and cold lateral condensation techniques were more acceptable than warm lateral condensation technique

[Comparison of remaining obturating material on canal walls using rotary and hand instrumentation techniques for endodontic re-treatment]

Inadequate removal of the original obturating material during non-surgical endodontic retreatment may lead to failure of root-canal therapy. The purpose of this in vitro study was to quantify and compare the percentage of root canal area occupied by remaining gutta-percha, employing rotary and hand instrumentation techniques with and without use of chloroform. Ninety extracted single-rooted human teeth were prepared by a passive step-back technique in three different working lengths: optimum increased [over-instrumented] and reduced [under-instrumented]. Obturation was performed by a combination of cold lateral and warm vertical compaction methods. The teeth were divided into 3 groups according to the methods used for gutta-percha removal: Group A, stainless steel K-type hand files plus chloroform; Group B, rotary Ni-Ti files plus chloroform; and Group C, rotary Ni-Ti files without chloroform. The roots were sectioned longitudinally and the percentage of root canal area occupied by root-filling material was calculated by a digital stereomicroscope in three levels: coronal, middle and apical. Data were analyzed by ANOVA. The coronal two-thirds contained larger amounts of filling material in all 3 groups, but the difference was not significant. A significantly smaller amount of gutta-percha/sealer was found in the middle and apical thirds in group C [P<0.05]. The relative percentage of canal area occupied by obturating material was not significantly different among the 3 working-lengths. The use of rotary files without solvent resulted in cleaner canals. However, completely clean root canal walls were not achieved with any of the studied instruments

[Evaluation of adhesion and morphology of human osteoblasts to white MTA/Gray MTA and IRM as root end filling materials by scanning electron microscopy]

Osteoblast and periodontal ligament cells are major cells for wound healing after root end resection. The interaction of osteoblast with directly contact filling materials could plays a critical role in healing of surgical lesion. Adhesion and spreading of cells on material surface are the initial phase for cellular function. The purpose of the present study was the evaluation of morphology and attachment of human osteoblasts in presence of Gray MTA, white MTA and IRM as root end filling material. This study was a descriptive study the human osteoblasts [MG-63 cell line] were prepared from Iranian Pasteur Institute; Cellular Bank, were grown in PRMI 1640 medium. The testing materials were mixed according to the manufacture's instruction, inserted into the wells of 24-well flat-bottomed plate, and condensed to disk of 1mm thickness and 1×1mm diameter. Cells were added to the materials after two weeks. During 1,3,7 days intervals, the disk of materials along with cells were grown on their surface, examined by a scanning electron microscopy. First day: After first day cells in presence of white and gray MTA showed adhesion and normal morphology, in presence of IRM were totally round. Third day: After third day osteoblasts adjacent to white and gray MTA were flat with adhesion to both materials. In presence of IRM they were round and with no attachment. Seventh day: In seventh day cells appeared with adhesion and normal morphology. Adjacent to IRM cells were round with no attachment. The results indicate that human osteoblasts have a favorable response to gray and white MTA compared with IRM

[Cytotoxic effect of amalgam and mineral trioxide aggregate on L929 cell line culture]

In many cases of endodontic treatment like retrograde surgery and perforation correction, because the materials are placed adjacent to vital connective tissue, biocompatibility and non cytotoxicity are of great importance and improve healing process. Among so many introduced materials, amalgam has been used for many years as a low cytotoxic material. Mineral Trioxide Aggregate [MTA] has been introduced as a new material with high biocompatibility and cementogenesis stimulation. The purpose of this study was the comparison of the cytotoxicity of amalgam and MTA on L[929] cell culture using light microscope. Different dilutions of fresh and set materials were placed adjacent to flasks of L[929] in DMEM media for 24h, 48h, 72h and 4 and 6 days. Then qualitative evaluation of cell morphology by light microscope were done. In qualitative evaluation on L[929] cells with light microscope, fresh-neat amalgam had a moderate cytotoxic effect as proliferation inhibition, whereas fresh MTA had a low cytotoxic effect. Set materials had no cytotoxic effects. According to our findings, MTA revealed a lower degree of cytotoxicity than amalgam. Thus MTA could be used nearby the vital connective tissue

[Stereomicroscopic evaluation of calcified canals for determining open spaces]

One reason for endodontic failure is calcified canals. Canals may be calcified radiographically or clinically but are not often completely obliterated. The purpose of this study was to determine the microscopic size of open spaces in clinically and radiographically calcified canals. In this in-vitro descriptive study 18 human extracted teeth including 21 calcified canals were selected and transverse sections were prepared in 0.8-0.9mm thickness and studied using a stereomicroscope. After taking digital photographs of these sections, open spaces dimensions were measured in each section using Auto Cad 14 program. Computerized evaluation of samples revealed varying dimensions of open spaces. Open spaces were observed in most of the canals, specially those with closed orifices. According to varying dimensions of open spaces in calcified canals, practitioners are recommended to be more persistent when negotiating canals with calcified appearances

Comparison of the extruded apical debris rate following rotary and hand instrumentation techniques during endodontic retreatment

Non-surgical retreatment is a way to correct the factors responsible for the failure of previous endodontic treatment. In recent years, rotary instrumentation systems have created a new option for both clinicians and patients. The aim of the present study was to quantify and compare the amount of debris extruded from apical foramen during endodontic retreatment using rotary and hand instrumentation techniques with and without use of chloroform. In this invitro experimental study, root canals of 96 extracted single-root human teeth were instrumented by passive step back technique in three different working lengths: optimum, over and under [three subgroups: a, b, c]. they were then obturated by a combination of cold lateral and warm vertical compaction methods. After removal of gutta-percha, re-instrumentation was performed in three groups as follows: group A; stainless sled K-type hand files plus chloroform, group B; rotary Ni-Ti files plus chloroform and group C; rotary Ni-Ti files without chloroform. Finally, the weight of extruded debris was blindly determined. The results were analyzed by Univariate ANOVA. In all groups, the mean weight for extruded debris was not more than 0.37 gr. The weight of extruded debris was ranked as: Group B>Group C>Group A. The differences between three groups and subgroups were statistically significant [P<0.001]. The results of this study showed that the largest amount of extruded debris during retreatment was found after using rotary files with solvent and in canals with overfilled obturation

[Histological evaluation of pulpal status in patients with periodontal diseases]

Introduction: the close relationship between endodontics and periodontics is firmly established. Many authors claimed that pulpal inflammation might occur following periodontal diseases. The purpose of this study was histological evaluation of pulp in teeth with periodontitis

Materials and Methods: 32 single root teeth with periodontal diseases and without any caries and restoration selected for extraction were used in this study. Extractions were done after special clinical and radiographical examination. Samples were fixed in 10% formalin and then decalcified by EDTA for three months. Six micron sections were prepared and stained by H and E. Pulp status was evaluated histologically under light microscope

Results: showed that the amount of inflammatory cells was directly related with mobility and pocked depth. Atrophy in pulpal vessels as well as calcific feature were found in samples with deeper pocket

Conclusion: the findings imply that pulp is significantly affected by periodontal diseases. This should be a carefully considered factor when dental treatment is planned