Journal of Dental Medicine

One of the major goals of periradicular surgery is to create a good apical sea! at the apex. This is done by sectioning of 2 to 3mm from the apex, preparation of a class I cavity and filling with a biocompatible material.The purpose of this in vitro study was to determine whether ultrasonic units used for root end preparations could change the surface & structure of resected root ends, as competed to common methods of retropreparation. Eighty-five extracted single rooted teeth were divided into five similar groups. Then instrumented and filled with lateral condensation method. Then three millimeter of apex was resected, retropreparaiions in two groups were done with low speed handpiece and round V) ^ur and cavities in two other groups prepared with the highest power of dentspiay ultrasonic unit with TFI-10 tip and in one other group prepared with the highest power of neo sonic ultrasonic unit with diamond coated CT-1 retro tip.Following root resection and retropreparation the surface of resected root ends were examined for the presence of any cracks or structural changes on the surface of resected root ends with stereo microscope 50x.The results of this study showed thai high power settings of ultrasonic units can increase the potential of crack formation on resected root surfaces. In conclusion it is better to use low power setting of ultrasonic for retropreparation.

One of the major goals of preradicular surgery is to create a good apical seal. This can be done by sectioning approximately one third of the apex, preparation of a class I cavity, and filling with a biocompatible material. The purpose of this in vitro study was to compare crack propagation in retro filling with two commercially available amalgams. Thirty-four extracted single rooted teeth were divided into two groups. After instrumentation and filling with Gutta percha by lateral condensation method, three millimeter of apex was resected and retro preparations were done by a low speed hand piece and '/> round bur. Then cavities were filled with cinalloy and luxalloy amalgam in-group "one" and "two" respectively. The surface of resected root ends was examined in two stages, after doing retro preparation and retro filling and the presence of any cracks or structural changes was inspected by stereomicroscope 50x. Regard to number and type of cracks, the result of this study showed that there was no significant difference between cinalloy or luxalloy retro fillings. By considering the conditions of this study, cinalloy amalgam can be used as a retro filling material.

Statement of Problem: Different materials have been suggested for endodontic surgeries. One of the most important characteristics of filling materials is their biocompatibiiity.
Aim: The aim of this research was to evaluate the biocompatibiiity of four different root end filling materials.
Material and Methods: In this study, 20 male Guineanpigs from English short hair breed, weighing 600-700 grams, were selected. The animals were classified into two groups. In the first group, amalgam and composite and in the second group MTA and Glass Ionomer were examined. The testing materials were shaped into cylindrical form with 1 mm diameter and 1.5 mm height. After general anesthesia, two
cavities with 1mm diameter and 2 mm depth were prepared in parasymphysis area of animal jaw. The prepared materials were implanted in these cavities and the flaps were sutured. After 80 days, the animals were sacrificed and the dissected bones, with implanted materials inside them, were sent for histological evaluation. The histological findings were statistically analysed by Kruskal Wallis and x'tests.
Results: No significant differences were shown in the degree of inflammation, the type of inflammatory cells adjacent to the tested materials and the type of tissue response, induced in the vicinity of these four materials during 80 days.

Conclusion: Regarding biocompatibiiity, there was no significant difference among amalgam,composite, MTA and glass Ionomer in endodontic surgeries.

Statement of Problem: Root canal cleaning and elimination of the source of infection are the most important basis and the main requirements for successful root treatment since the main cause of failure in root treatment is the permeation of bacteria or their products into the periapical tissues. Nowadays, the newly designed and prcsented instruments for canal instrumentation can improve root treatment.

Purpose: The aim of this study was to compare the decrease in the number of intracanal Enterococcus-faecalis (Ef) among three mechanical instrumentation methods: manual (K-type) and rotary (Race, Profile).

Materials and Methods: In this experimental study, 30 single rooted teeth were selected. Three cases were considered as negative and three cases as posetive controls and 24 remainder cases were divided into three experimental groups. All root canals were inoculated by Ef and samples were taken from all canals to prepare microbial cultures. The three instrumentation procedures were: - Crown- down technique with K-type manual system file - Crown- down technique with Profile rotary system - Crown- down technique wiht Race rotary system After instrumentation, microbial cultures were taken from root canals and the reduction rate of bacteria were evaluated and compared using one way ANOVA test with P<0.05 as the limit of significance.

Results: There was no significant difference among the three instrumentation procedures regarding bacterial elimination.

Conclusion: According to the finding of this study, K-type manual file, Profile and Race rotary systems, all can be used in canal instrumentaion. However, since manual files are more accessible and require less equipment compared with rotary systems, and since the ability of all of these methods is identical regarding bacterial elimination, manual files can be used in straight canal instead of rotary systems.

Background and Aim: Mechanical preparation of canal is one of the most important stages in root canal therapy. Various kinds of hand or rotary techniques are used for mechanical preparation of canal and each of them has advantages and disadvantages. During canal preparation, extrusion of debris from the apical foramen can result in periapical inflammation and increased pain and edema. The aim of this study was to compare hand instrumentation technique with three rotary systems (Profile, Race, Flex Master) regarding the amount of extruded debris from apical foramen during canal preparation.

Materials and Methods: In this experimental in vitro study, one hundred human extracted single rooted mandibular premolars with curvature between 0-10 degrees were selected and divided into four groups of 25 teeth each. All teeth were shortened to 15 mm length by cutting the crown. Group H was prepared by hand step back technique, group P by Profile system, group R by Race system and group F by Flex Master system. For debris collection, vials containing distilled water were used which were weighed before preparation. After the end of canal preparation, vials were completely dried and weighed again. The difference between weights of vials in two stages was the weight of debris extruded from apical foramen. The groups were compared by One-way ANOVA with p<0.05 as the level of significance.

Results: Group H had the highest mean weight of debris which showed significant difference with all three rotary groups (P<0.001). The lowest mean weight of debris was observed in group R (Race) which was significantly different from group F (Flex Master) but not significantly different from group P (Profile).

Conclusion: Based on the results of this study, race rotary system caused less debris extrusion from apical foramen compared to hand step back technique and Flex Master rotary system.

Background and Aim: Furcal perforation has a great impact on prognosis of endodontic treatments, requiring immediate and proper intervention. Gray MTA is applied as material of choice in repairing perforations. The aim of this study was to evaluate the repair of mechanical furcal perforations, histologically using white MTA and Portland cement and compare them with gray MTA.

Materials and Methods: In this experimental study, second to fourth mandibular and maxillary premolar teeth of five dogs received endodontic treatment, then the furcation area of the teeth were perforated and repaired as follow: gray MTA in group1, white MTA in group 2, Portland cement in group 3 and cotton pellet in group 4 (control). Animals were controlled for 4 months and sacrificed using an over dosage of sodium thiopental intravenous injection and perfusion of 10% formaldehyde. Chi-square and Fisher exact tests were used to compare hard tissue formation between groups and between each two groups, respectively. Non-parametric Kruskall Wallis and Dunn procedure were also used to compare degree of inflammation among groups and between each two groups, respectively.

Results: Gray MTA had more favorable results (90.9% hard tissue formation and only 9.1% severe inflammation) but the difference between gray MTA, white MTA and Portland cement was not statistically significant.

Conclusion: The difference between gray MTA, white MTA and Portland cement groups was not statistically significant for degree of inflammation and hard tissue formation. In conclusion both white MTA and Portland cement can be used instead of gray MTA to repair perforations in accordance to esthetic considerations.

Background and Aim: Mineral Trioxide Aggregate (MTA) is a material used in many endodontic problems. Recently a number of studies, have reported that Portland Cement (PC) and MTA have similar physical, chemical and biologic properties. In addition, a material known as Root MTA which is produced in Iran has been claimed to have similar properties to Pro Root MTA. If these claims are true, possible use of PC and Root MTA in clinic instead of Pro Root MTA will be quite cost effective. The aim of this study was to investigate the toxicity of Pro Root MTA, Root MTA and Portland Cement on L929 mouse fibroblasts.

Materials and Methods: In this experimental study 0, 4, 24 hours and 7 days' extracts of materials were transferred to cell culture plates containing L929 fibroblasts. After 24 hours incubation, cells were stained by Neutral Red (NR), and optical density (OD) of each cell was read with ELISA reader. Data were analyzed using Tukey HSD and one way analysis of variance. P<0.05 was considered as the level of significance.

Results: In all surveyed groups and negative control group, at all time points separated cells from the base of the well were round. Refraction which is a characteristic of cellular death was not observed, whereas the separated cells from the base of well in positive control group showed refractional characteristic.

Conclusion: Based on the findings of this study Pro Root MTA, PC and Root MTA have the same biocompatibility. PC seems to have the potential to be used in the same clinical situation as MTA. However in order to replace MTA with these less expensive materials more in vitro and in vivo studies are suggested.

Background and Aim: Root filling materials are usually in close contact with living tissues. So their biological properties like mutagenicity and cytotoxicity are important. These properties help us determine the potential damage to periapical tissues, or potential DNA mutations, and malignant transformation of the cells. The aim of this study was to evaluate the mutagenicity and cytotoxicity of four root canal sealers: AH Plus (Dentsply, DeTrey), Ketac-Endo Aplicap (3M ESPE), Sankin Apatite III (Sankin K.K), and Tubli-Seal EWT (Kerr).

Materials and Methods: In this experimental in vitro study fresh and set specimens from AH Plus, Ketac-Endo Aplicap, Sankin Apatite III, and Tubli-Seal EWT were immersed in culture medium for 1, 2 and 7 days. Cytotoxicity was assessed using tetrazolium bromide reduction assay (MTT) after 1, 2 and 7 days exposure of diluted extracts to L929 cells. Extracts of sealers in phosphate buffer saline (PBS) were used to examine the mutagenic effects by sos-umu test according to standard procedures. Data were analyzed using one way ANOVA, Kruskall Wallis, Mann Whitney and Post hoc tests with P<0.05 as the level of significance.

Results: Extracts of all freshly mixed sealers were cytotoxic. Ketac-Endo Aplicap and Sankin Apatite III showed the lowest toxicity respectively and Tubli-Seal EWT the highest. In contrast to other sealers, the cytotoxicity of Tubli-Seal showed no decrease with time. -galactosidase did not increase significantly thus none of the sealers showed mutagenic effects.

Conclusion: Based on the results of this study, Tubli-Seal EWT showed the highest cytotoxicity with time. Other sealers showed decreasing cytotoxicity with time. No mutagenicity effects was observed in none of  tested materials.