[In Vitro Evuluation of Flow and Working Time of AH PIus Alone and in Combinution with Amoxicillin und Triple Antibiotic Paste]

Background and Aim: Some researchers have attempted to enhance the antibacterial properties of sealers byaddition of antibiotics while this may affect their physical properties.The purpose of this in vitro study was to comparethe working time and flow of AH Plus sealer alone and in combination with amoxicillin and triple antibiotic paste [TAP]

Materials and Methods: This in vitro study assessed the flow and working time of AH Plus alone [control group] and in combination with amoxicillin and TAP in 1%, 5%, 10% and 25%concentrationsaccording to ANSI/ADA specification NO. 57. The data were analyzed by ANOVA and Tukey's test.

Results: Statistically significant differences were noted in the flow and working time of control group with those of different concentrations of TAp in combination with sealer [p<0.0001].]. The working time decreased by an increase inthe concentration of TAp. The AH Plus/ 1% TAP and AH Plus/5% TAP showed higher flow than the control group. The AH plus /1% amoxicillin, AH Plus/5% amoxicillinand AH Plus/l0% TAPhad a flow similar to that of the control group. Other groups showed lower flow than the control group.

Conclusion: All the alterations in the physical properties of AH Plus sealer in combination with amoxicillin and TAPwere within the ANSI/ADA specification NO 57 standard range.

[Clinical accuracy of lpex apex locator for measurement of root canal length of primary molars]

Radiography is the most commonly used technique for root canal length determination; but its application in pedodontics is difficult due to problems namely the radiation hazards, superimposition of permanent teeth buds and uncooperative children. Electronic apex locator [EAL] is used for determination of root canal length. The aim of this study was to assess the accuracy of an Electronic Apex Locator [Ipex] in measuring the root canal length of primary teeth in-vivo. This clinical study was conducted on 50 root canals of primary teeth that had to be extracted. After local anesthesia induction and caries removal, access cavities were prepared and the length of root canals was measured using Ipex Electronic Apex Locator. After the extraction of teeth, the actual length of canals was measured using a #15 K file from a reference point. Data were analyzed using paired t-test and intra-class correlation coefficient. The accuracy of Ipex was 20% for accurate determination of actual root canal length, 66% for estimation within +/- 0.5mm of the apex and 80% for estimation within +/- 1mm of the apex. Paired t-test revealed a significant difference between the actual root canal length and the length displayed by Ipex [P<0.001]. A direct strong correlation existed between the length measured by Ipex and the actual root canal length [r=0.957] Ipex had a tendency to underestimate the actual root canal length. Since the working length is shorter than the actual root canal length, Ipex may be used for endodontic treatment of primary teeth

Experimental study of smear layer and debris remaining following the use of four root canal preparation systems using scanning electron microscopy

Since the use of rotary nickel titanium instruments is an essential part of endodontic treatment, it is important to compare the root canal cleaning ability of these instruments. The aim of this study was to compare the amount of smear layer and debris remaining following the use of four rotary instruments: MTwo, Pro Taper, Race and BioRaCe. A total of 20 mesiobuccal canals of extracted human first molars with apical root curvature of 10 to 20 were selected. Working length of all roots was 19 mm. The roots were randomly divided into four groups of 30 specimens. After the preparation of access cavity, the roots were instrumented using rotary instruments according to the manufacturer's instructions. After each file, the root canal was irrigated with 2.5%sodium hypochlorite. Then the roots were studied under scanning electron microscope. The smear layer and debris scoreswere evaluated by 2 endodontistsusingSchafer and Schlingemannclassification. Kruskal -Wallis and Dunn tests were used for statistical analysis of results. The amount of smear layer produced by MTwo was lower than the other instrumentation techniques and it was significantly lower than that in BioRaCe system [p<0.05]. The amount of debris was also lower in the mentioned group but the difference in this respect between groups was not significant. BioRaCe system had the highest level of remained smear layer while Pro Taper had the highest amount of remained debris. Within the limitations of this study, it was revealed that MTwo instruments had greater capability of removing smear layer and debris than theBioRaCe system

[Comparison of stress between endodontists, postgraduate and undergraduate students during endodontic therapy]

Endodontic therapy is considered as one of the most stressful dental treatments. This study was designed with the aim of comparing stress levels during different stages of endodontic treatment among endodontic professionals under- and post-graduate students. In this ex-post facto investigation, three groups including professional endodontists [n=36], undergraduate [n=41] and postgraduate dental students [n=47] were involved by convenience sampling. A questionnaire including 48 items, with five-point scales [very few to very much], was prepared for this study based on interview. The questionnaire was filled out by participants in a self report method. Data were analyzed by multivariate analysis of variance and Scheffe's post - hoc tests. The stress among undergraduate dental students in all fields were more than those of professionals and postgraduate dental students, except for the stress of local anesthetic injection with lidocaine. Stress levels of all three groups were significantly different in inferior alveolar block injections with lidocaine, with professionals having more stress than under- and post- graduate dental students. The most stressful aspect of endodontic treatment, among the three groups was canal obturation, followed by obturation of the molar canals, preparing molar access cavities in special conditions and taking the final radiographs. The suggested methods offered for occupational stress reduction, was experience and knowledge, adequate knowledge, concentration and self confidence, and trust to God, respectively. The stress among under graduate dental students in all fields was more than professionals and post graduate dental students, except for the stress of local anesthetic injections with lidocaine

[Effect of different polishing methods and composite resin thickness on temperature rise of composite restorative materials]

Along with improvements in aesthetics and longevity of restorations, finishing and polishing, can produce potentially injurious temperature rise within the pulp chamber. The purpose of the current study was to find whether different polishing methods and thickness of composites have any effect on temperature rise of composite restorative materials. Sixty composite resin specimens 9 mm in diameter were prepared and assigned to three experimental groups with three sample thicknesses [2, 3 and 4mm]. Each group was divided into four subgroups randomly. Polishing in subgroups 1 and 2 [continuous and intermittent dry polishing] and subgroups 3 and 4 [continuous and intermittent wet polishing] was carried out with a slow speed contra-angle hand piece at a medium speed for 120 seconds in a roll on motion. Immediately after polishing, temperature was measured on the top and bottom surface of each sample using a laser thermometer. One and two way ANOVA, Duncan, and paired T-test was used to analyze the data. The mean temperature rise after polishing in different methods was significant; continuous dry polishing produced the maximum temperature rise. In addition, increasing the thickness of composite resin up to 4mm did not significantly affect thermal transfer from the top surface to the base during polishing. Copious use of water coolant during finishing and polishing procedures is considered a simple and effective method for pulpal protection. Increasing the thickness of composite resin does not have a significant role in compensating the heat generated during polishing procedure

[ cleaning efficacy of manual files compared with two rotary instruments in the root canal of permanent molars: an in vitro study]

Rotary files may be cause anatomical changes in apical area. The aim of this study was evaluation of maintenance of the canal's curve using Flex Master and Protaper rotary instruments. In this in vitro study, we used 30 mesiobuccal roots of first permanent maxillary molars with a mean length of 18-23 milimeters and a mean curve of 15-40 degrees. Sampling was simple and the specimens were divided into two groups of fifteen. In each group, the canals were prepared by crown down method after the access step. Then they were prepared using Flex master and Protaper according to their company's instruction. After finishing the preparation steps, hand instrument number 30 was placed in the canals and under the same primary condition we evaluated the final angle by digital radiographic system. For evaluation of the results, we used variance analysis, t test and covariance analysis. The mean angle of apical transportation after using two Flexmaster and Protaper rotary systems was 6/19 +/- 3/07 and 5/52 +/- 2/87 degree, respectively. The mean apical transporation using the Flexmaster system was more than Protaper system but the difference between them was insignificant [P>0/ 05]. Because of using these two rotary systems, we had apical canal transportation. This transportation by using Flexmaster system was more than the Protaper system, but it was not significant

[Comparison of smear layer removal of root canals with citric acid and EDTA- NaOCl [A SEM study]]

The smear layer is a thin layer composed of organic and inorganic debries which forms on canal walls. Removal of this layer after instrumentation is critical for adaptation between filling material, root walls and apical seal. The aim of this in vitro study was to determine the effect of 30% citric acid and 17% EDTA- 5.25% NaOCl on smear layer removal in the middle third of root canals. In this experimental study, twenty extracted anterior teeth were used. After decoronation, instrumentation was done. The teeth were divided into three groups. After final preparation the canals were irrigated by 10 ml 30% citric acid in group I and 10 ml 17% EDTA followed by 5.25% NaOCI in group 2. In control specimens, normal saline was used. Then the roots were split longitudinally and studied under scanning electron microscope. The photomicrographs were evaluated by X and Y methods. The data was analyzed by Kolmogorov-Smirnov, Leven's, Mann Whitney U and T-student tests. Canal walls were covered with smear layer in the positive control group. in both methods [X, Y], the result showed that canals irrigated with 17% EDTA- 5.25% NaOCL had less smear layer throughout the canal than group irrigated with 30% citric acid. This difference was not statistically significant in both [X, Y] methods. Both 17% EDTA-5.25% NaOCL and 30% citric acid removed the smear layer from root canal walls effectively

[Biocompatibility comparison of two different sealers AH26 and Apexit: in-vivo animal model]

There are a few conditions that prove a sealer to be suitable for use in practice. One of the important factors in a good sealer is its biocompatibility. The purpose of this in-vivo study was to compare the biocompatibility of two types of endodontic sealers; AH26 and Apexit by using animal model. A total of eleven white rats were included in this interventional in-vivo study. After sedation of rats, two sealers [AH26 and Apexit] were implanted in the subcutaneous tissue of each rat. AH26 was implanted in two sites of subcutaneous tissue in the left side and Apexit was implanted in two sites in the right side and the control site was designated in between them. In control group, the incisions were made similar to AH26 and Apexit groups and sutured without insertion of any material. Biopsies were taken from five rats after three days and from the other six rats after thirty days. Histological specimens were studied by pathologist and findings were reported. Data was analyzed using appropriate statistical procedures as well as Mann-Whitney and Kruskal-Wallis tests in order to report the significance level. Although Apexit caused more inflammation compared to AH26, after 3 and 30 days, but such difference was not statistically significant [P>0.05]. However, both sealers initiated mild to moderate inflammation when judged against control group and the difference was statistically significant [P<0.05]. Even though AH26 and Apexit cause inflammation in subcutaneous tissues of rats but they have moderate biocompatibility as the inflammation was graded two in this study according to the pathologic report

Comparison of irrigation penetration into the apical part of canals in hand and rotary instrumentations

The penetration of irrigating solution to the apical one third of canals and removal of debris are dependent on the final size of the instruments and instrumentation techniques used in the canals. The purpose of this study was to evaluate the effect of final instrument size, on irrigation penetration into the apical part of canals in hand K-file instrumentation versus rotary system of Hero 642. The mesiobuccal canals of 48 first mandibular molar teeth were selected for this study. The teeth were divided into 2 groups of 24 in each and the mesiobuccal canals were instrumented by hand K-file or rotary system of Hero 642 at 2 stages. After each stage, a contrast medium was injected into the canals and radiographs were taken by RVG system. The irrigation penetration was measured in radiographs by Diamax software. The data were analyzed using t -student test. This study showed that instrumentation up to # 25 file is not enough for irrigation penetration into the apical area. Also by more flaring the canals, more irrigating solution penetrates into the apical part of canals [P < 0.001], but the difference between hand and rotary systems was not statistically significant [P > 0.05]. According to this study, instrumentation up to # 30 file results in better irrigation penetration into the apical area. The flaring of the canals is essential for better cleaning and irrigation of apical area

Extra oral comparison of smear layer removal from root canals when using phosphoric acid and RCprep-NaOCL: a SEM study

The smear layer is a thin layer of microcrystalline and organic debris which forms due to instrumentation of canal walls. Today, it is known that the smear layer contains bacteria as well as the nutrients necessary for bacteria. However, it is at the same time a barrier against penetration of irrigants and filling materials into dentinal tubules. Thus it is a factor that can cause micro-leakage and treatment failure. Smear layer removal will increase the adaptation between filling material and canal walls, and therefore it improves the overall sealing quality. Obtaining the cleanest canal possible before obturation is one of the goals of Endodontic treatment. The purpose of this in vitro study was to evaluate the smear layer removal ability of the 10% phosphoric acid and RCprep-5.25% NaOCL in the middle third of the root canals. Twenty freshly extracted human mature anterior teeth with single root canals were used in this study. Then the teeth were divided into three groups. Root canal instrumentation was conducted after decrownation of teeth at the CEJ level. Normal saline was used as irrigants during instrumentation in group 1. After final preparation, the canals were irrigated by 10 ml 10% phosphoric acid for 5-min. In group 2, the irrigants used during instrumentation by files coated with RCprep was 2 ml 5.25% NaOCL. At the end, both groups were irrigated with 5 ml normal saline. In 2 control specimens [teeth], normal saline was the only irrigants used during instrumentation. The roots were first split longitudinally, and then one section was randomly selected for further analysis under the electron microscope. The photomicrographs were evaluated by two different investigators [in group 1] and three different investigators [in group 2]. Statistical analysis was performed to detect group differences and student-t test was used to determine the significance level. Canal Walls were covered with smear layer in control group. The results showed that canals irrigated with 10% phosphoric acid had less smear layer throughout the canal walls compared with the group prepared with RCprep that contained 5.25% NaOCL. This difference was statistically significant in method used in group one [P<0.05] only. Based on the findings of this study, 10% phosphoric acid is superior to RCprep - 5.25% NaOCL in terms of removing smear layer from root canal walls

Histological evaluation of inflammation after sealing furcation perforation in Dog's teeth by four materials

The materials used in sealing furcating perforation can have considerable effects on controlling the ensuing inflammation and periodontal repair. The objective of the present study was to carry out a histological comparison between the effects of pro-root, cold ceramic, glassionomer cement, and root MTA on the healing of periodontal tissues after furcal perforation in dog's teeth. One-hundred premolar teeth of one-year old dogs were used in this experimental/animal study. After anesthetizing the dogs and the premolar teeth, the access cavities were prepared at the occlusal level and the root canals were instrumented and filled with gutta percha and AH26 sealer, using the step-back technique. Furcations were perforated to a size of 3X3 mm2, using long burs. These areas were then randomly filled with aforementioned four test materials [a total number of 84 premolar teeth] while the access cavities were filled with amalgam. The remaining 16 teeth were selected to serve as positive and negative controls. Biopsy samples were taken from the perforated areas at 1, 2, and 3-month intervals and were transferred to laboratory for pathological examination. The results were statistically analyzed, using the Kruskal Wallis and Mann Whitney tests. The statistical analysis revealed that under similar conditions, periodontal tissues surrounding Pro-root, show less inflammatory response than the other three materials. However, no significant differences were observed among the four studied materials during 1 and 2months as evidenced by the biopsy samples [P>0.05]. For longer period [three month], however, samples surrounding cold ceramic and Root MTA showed decreasing inflammatory responses. From the findings of the present study, it may be concluded that although tissues adjacent to Proroot showed less inflammatory response than other three test materials, all of them [Proroot, Glass-ionomer cement, cold ceramic, and Root MTA] may be considered to be suitable materials for sealing furcal perforation providing. They receive approval by other tests including micro leakage, cytotoxicity, tissue analysis, and etc

Histological investigation of glass-inomer and pro-root effects in healing of periodontal tissues after sealing furcation perforation in dogs' teeth

In root canal therapy some accidents may happen that affects the prognosis of the tooth. For example, when preparing access cavity, perforation of furca is a possibility that leads to tooth loss. Important factors in prognosis of furcation perforation include: the kind of materials used, area that perforation has happened in, time in which perforation is sealed and skill of clinician. Because the kind of material used is important in control of inflammation and periodontal repair, we decided to compare effects of two materials Glass-ionomer and pro-root in this role. Thirty five teeth from one year old dogs were used in this research. It was an exprimental study and done in prof-M.Torabinejad dental research center. After anesthesia and injection of lidocaine, access cavity was prepared and root canals were cleaned by step-back technique and then filled.Furca was perforated by long burs of 3'3 mm. Areas were washed by serum to control bleed-ing.Perforated zones were sealed accidentally by pro-root and glass-ionomer and then the cavities filled by amalgam. Six teeth were considered as positive and negative controls. Two dogs were sacrifized after one month and two after two months by vital perfusion method. Jaws and teeth were seperated and put in formaline [10 percent]. After laboratory procedures and preparing parafine blocks the samples were investigated by microscope. In this research we found that there is no important difference between two material after one and two months but in the same condition pro-root may cause more repair. Both glass-ionomer and pro-root will lead to repair of supporting tissues but inflammation near pro-root is less and periodontal regeneration, Cement and bone formation is more