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BACKGROUND: Nitric oxide (NO) has several functions in bone healing and affects bone metabolism. Selective inducible NO synthase (iNOS) inhibitors can be used to assess the efficacy of NO for healing of bone defects. This study sought to assess the local effect of different concentrations of aminoguanidine hydrochloride (AG), a selective iNOS inhibitor, on bone healing in rats. MATERIALS AND METHODS: In this animal experimental study, 72 rats were divided into six groups of control, placebo, 5% AG, 10% AG, 15% AG, and 20% AG. A bone defect measuring 5 mm × 5 mm was created in the femur. The defect remained empty in the control group. In the placebo group, neutral gel was placed in the bone defect, and in the remaining four AG groups, different concentrations of AG were applied to the defects. Bone healing was assessed histologically. The healing score in the six groups was analyzed by the Kruskal-Wallis test. A P < 0.05 was considered statistically significant. RESULTS: The healing score in 20%, 15%, 10%, and 5% AG groups was significantly higher than that in the neutral gel and control groups (P < 0.01). Among the four groups of AG, 20% concentration showed better results, but the difference was not significant. CONCLUSION: Four concentrations of AG caused greater bone healing compared to the other two groups. Selective iNOS inhibitors such as AG can be used to promote local bone healing.

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BACKGROUND: Nitric oxide (NO) has many functions in wound healing and bone metabolism. This study sought to assess the local effect of aminoguanidine (AG), a selective inducible NO synthase (iNOS) inhibitor, on the rate of bone healing. MATERIALS AND METHODS: This experimental interventional study was conducted on 36 rats, which were randomly divided into three groups of control, placebo, and AG. Bone defects measuring 5 mm × 5 mm were created in the femur. In control group, bone defects remained empty. A placebo gel was applied to defects in the placebo group. AG gel was placed in bone defects in AG group. New bone formation and healing were assessed using histological and histomorphometric analyses. The healing score and the percentage of new bone formation (total bone mass, immature bone, and mature bone) were compared among the three groups using the Kruskal-Wallis test and analysis of variance, respectively. A P < 0.05 was statistically significant. RESULTS: The mean healing score in AG group (3.17 ± 0.577) was significantly higher than that in control (2.67 ± 0.49) and the placebo (2.58 ± 0.515) groups (P = 0.036). The percentage of new mature (lamellar) bone in AG group (22.06 ± 1.90) was significantly higher than that in control (20.94 ± 2.03) and the placebo (20.53 ± 1.20) groups (P = 0.008). CONCLUSION: The rate of bone healing was faster in the AG compared to the other two groups. Local application of selective iNOS inhibitors like AG may be efficient as an adjunct in the clinical setting where local bone formation is required.

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INTRODUCTION: The purpose of this prospective, randomized, double-blind study was to evaluate the effect of a buccal infiltration of sodium bicarbonate on the anesthetic success of the inferior alveolar nerve block (IANB) for mandibular first molars in patients with symptomatic irreversible pulpitis. METHODS: One hundred patients diagnosed with symptomatic irreversible pulpitis of a mandibular first molar were selected. The patients randomly received a buccal infiltration injection of either 0.7 mL 8.4% sodium bicarbonate with 0.3 mL 2% lidocaine containing 1:80,000 epinephrine or 0.7 mL sterile distilled water with 0.3 mL 2% lidocaine containing 1:80,000 epinephrine in a double-blind manner. After 15 minutes, all the patients received conventional IANB injection using 3.6 mL 2% lidocaine with 1:80,000 epinephrine. Access cavity preparation was initiated 15 minutes after the IANB injection. Lip numbness was a requisite for all the patients. Success was determined as no or mild pain on the basis of Heft-Parker visual analog scale recordings upon access cavity preparation or initial instrumentation. Data were analyzed using the t, chi-square and Mann-Whitney U tests. RESULTS: The success rate after the buccal infiltration of sodium bicarbonate was 78%, whereas without the buccal infiltration of sodium bicarbonate it was 44% (P < .001). CONCLUSIONS: A buccal infiltration of 0.7 mL 8.4% sodium bicarbonate increased the success rate of IANBs in mandibular first molars with symptomatic irreversible pulpitis.

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Endodontic treatment of immature necrotic teeth is a real challenge. Recently, a biologically based treatment strategy, referred to as regeneration, has been introduced. Tissue regeneration requires the presence of stems cells, a scaffold, and growth factors. Endodontic regeneration may improve the prognosis of immature necrotic teeth by re-establishing the functional pulpal tissue and further development of the root. However, the tissue formed in the pulpal space may not be original pulp tissue, and in some cases, it may result in uncontrolled calcification of the pulp. This study reports a case of successful endodontic regeneration and compares this process with the normal development of the contralateral tooth. Finally, it discusses the nature of the tissue formed during endodontic regeneration.

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OBJECTIVE: Electronic apical foramen locators are now widely used to determine working length. This study was designed to determine whether tooth length influenced the accuracy of the Root ZX device. MATERIALS AND METHODS: Forty extracted maxillary canine teeth with a length range of 27-29 mm were selected. Access cavities were prepared and coronal flaring of canals performed. The teeth were mounted in self-polymerizing acrylic resin to facilitate horizontal sectioning except for the apical 3-4-mm portion of the root and embedded in alginate as the electronic medium. Electronic measurements were taken at the major foramen, 'zero' reading using the Root ZX and compared with the actual root canal length. The teeth were sectioned 3 mm from the coronal reference point to create a second group with shorter length; these reductions in the length continued six times in all to create seven groups of 40 specimens each. The actual and electronic lengths of specimens in each group were measured. Data were analyzed by Pearson's correlation coefficient. RESULTS: Identical measurements between the actual and electronic root canal length from the longest to the shortest groups were 12.5%, 10.0%, 20.0%, 27.5%, 37.5%, 35.0% and 45.0%, respectively. There was a mild negative correlation between the precise measurements of the Root ZX and root canal lengths in the seven groups (r = -0.964, p < 0.001). CONCLUSION: Under the conditions of the study, the Root ZX device was more accurate in shorter teeth compared to longer ones.

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BACKGROUND: The incidence of dentinal defects may influence the outcome of root canal treatment. The aims of this study were to evaluate and compare the incidence of dentinal defects following root canal obturation with two different techniques. MATERIALS AND METHODS: A total of 110 mesial roots of human mandibular first molars were selected. Twenty-seven roots were left unprepared as negative controls (NCs). The mesiobuccal canals of 83 roots were prepared using rotary instruments. Twenty-seven roots were left unobturated as positive controls (PCs). Twenty-eight roots were obturated with cold lateral compaction (CLC) technique and the others were obturated with mechanical lateral compaction (MLC) technique. In the CLC and MLC groups, spreader penetration depth was measured by an electromechanical testing machine in canals containing master Gutta-percha cones. After root canal obturation, all the roots were sectioned horizontally at four levels from the apex and evaluated under a stereomicroscope at a magnification of ×40. The presence of dentinal defects was noted. Data were analyzed using the Chi-square and t-tests. RESULTS: The number of defects was not significantly different between the CLC, MLC, and PC groups. The CLC, MLC, and PC groups had significantly more defects compared to the NC group. CONCLUSION: According to the results of this study, the MLC and CLC techniques were the same in producing dentinal defects.

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The aim of the present study was to compare the antibacterial effect of calcium hydroxide (CH), triantibiotic mixture (TAM), and CH in combination with chlorhexidine (CHX), sodium hypochlorite (NaOCl) or colchicine (COL) against Enterococcus faecalis (E. faecalis) in surface and deep dentinal tubules. Seventy five fresh single-rooted human teeth were infected and divided into five experimental groups (n=15). The experimental groups were treated with CH+distilled water, CH+CHX, CH+NaOCl, CH+COL+distilled water and TAM+distilled water. Dentin chips obtained from surface and deep dentin of these root canals were prepared and analyzed by counting the number of colony forming units. There was significant difference between groups in the surface dentin (p<0.05). TAM showed higher antibacterial activity compared to CH-containing groups. There was no significant difference between TAM and CH-containing groups in the deep dentin (p>0.05). CH-containing medications and TAM can be used as effective disinfectants in treatment of infected root canals.

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OBJECTIVE: Recurrent aphthous stomatitis (RAS) is a common, painful ulcerative disorder of the oral cavity with unknown etiology. No documented cure exists and topical application of medications aims to reduce pain associated with this condition. The aim of this study was to evaluate the efficacy of Punica granatum (PG) extract on the clinical management of RAS. METHODS: A total of 40 patients with RAS participated in this randomized, double-blind, and placebo-controlled study. During three episodes of RAS, the efficacy of topical PG gel (10%) was evaluated. Patients were randomly assigned to use placebo gel or PG gel daily. The time of pain elimination and the time of complete healing were recorded and the pain degree was assessed and recorded by each patients in different time intervals including: Before using the oral gel (day 0), and on days 1, 3, 5, 7 after using the product. Data were analyzed using the repeated measures ANOVA, paired and independent t-test. FINDINGS: Mean time of pain elimination showed a significant difference (P < 0.001) between PG group (3.4 ± 1.09) and placebo group (5.9 ± 0.6). The mean duration of complete healing also showed a significant difference (P < 0.001) between PG group (5.3 ± 0.81) and placebo group (8.6 ± 0.99). The visual analog scale score in PG group was significantly less than the placebo group in all time intervals (day 1 to day 7) (P < 0.001). CONCLUSION: The findings of this study revealed that PG extract in the form of oral gel (10%) may be beneficial in reducing RAS pain and has a positive effect in reducing the overall time period of complete healing. It was concluded that PG is an effective herbal medicine for the management of RAS.

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INTRODUCTION: Antimicrobial activity of interappointment intracanal medications is an important consideration in endodontics. Considering the fact that calcium hydroxide (CH) cannot sterilize the root canal system, completing its antimicrobial spectrum seems necessary. The aim of this study was to compare the antibacterial activity of CH combined with three different vehicles in root canal system. MATERIALS AND METHODS: In this in vitro experimental study, 61 freshly extracted human single rooted teeth were used. After chemo-mechanical preparation, the teeth were dressed with CH in combination with: G1: Distilled water (DW); G2: 5.25% sodium hypochlorite; G3: 0.2% chlorhexidine solution. All teeth were mounted in a 2-chamber apparatus. After sterilization, the coronal chamber was exposed to bacteria and the apical chamber was filled with broth for 90 days. Leakage was recorded when turbidity was observed in broth. Mean times of leakage and turbidity percentage were recorded for each group. Data were analyzed by One Way ANOVA test (α=0.005). RESULTS: The highest mean time of contamination was for chorhexidine/CH combination (M=66.76 days), and the lowest was for DW/CH combination (M=40.29 days). Statistically significant difference was observed between G3 and G1 (P=0.042), but the difference between G2 and G3 (P=0.76) or G1 and G2 (P=0.18) were not significant. 88.23% of the samples of G1, 70.58% of G2, and 64.70% of G3 were contaminated after 3 months. CONCLUSION: As an intracanal medication, the chlorhexidine/CH combination had significantly more antibacterial activity than DW/CH combination.

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BACKGROUND: Mineral trioxide aggregate (MTA) is a multi-purpose dental material with various uses in dentistry. Iodine potassium iodide (IKI) is the most commonly used iodine compound in endodontics. We aimed to assess the antimicrobial activity of tooth-colored ProRoot MTA combined with IKI. MATERIALS AND METHODS: The antimicrobial activity of IKI was assessed at three concentrations (1%, 2%, and 4%) as the mixing agents combined with MTA against Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. For each microorganism, three plates were inoculated with 100 µl of a microbial suspension (McFarland 0.5). Four wells were prepared in each plate. MTA (70 mg) was mixed with any of the three concentrations of IKI (25 µl) or sterile distilled water (25 µl) and placed in each well. The plates were incubated for 24 h at 37°C. Zones of inhibition (ZOI) were measured in millimeters by a blinded observer. Data were analyzed using analysis of variance and the Dunnett t-test. RESULTS: All MTA mixtures with water or IKI solutions showed inhibitory zones. The mean ZOI of each MTA/IKI mixture was not significantly different from MTA/water mixture (P > 0.05). MTA/1% IKI had smaller ZOI than MTA/water against E. coli, E. faecalis, and C. albicans. MTA/2% IKI showed larger ZOI only against P. aeruginosa. MTA/4% IKI showed larger ZOI against P. aeruginosa and E. coli (P < 0.05). CONCLUSIONS: Substitution of IKI solutions (1%, 2%, and 4%) for water did not significantly increase the antimicrobial activity of MTA.

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BACKGROUND: Nitric oxide (NO) is one of the many chemical mediators involved in inflammatory processes. In addition to periapical inflammation, NO can have a role in periapical healing. The purpose of this study was to evaluate the effect of aminoguanidine (AG) as a selective inhibitor of inducible nitric oxide synthase (iNOS) on the degree of healing response of periapical lesions of the canine teeth of cats. METHODS: In this interventional experimental study, the root canals of 48 cat canine teeth were infected with cat dental plaque and sealed. After induction of periapical lesions, root canal therapy (RCT) was performed. On the day of RCT phase, the cats were administered either AG (experimental group) or normal saline (control group), which was continued on a daily basis until the day of sacrifice. Four canine teeth in one cat served as negative and positive controls. The animals were sacrificed 6 weeks after RCT. The healing response of the periapical zones was analyzed histologically. The mean scores of healing for the two groups were compared using Mann-Whitney U test. RESULTS: The mean scores of healing for the AG group (2.45±0.508) were significantly higher than those of the control group (2±0.510) (P<0.05). CONCLUSION: The use of an iNOS selective inhibitor such as AG can accelerate the healing process in periapical lesions.

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Dens invagination (DI) is a developmental abnormality of teeth which frequently results in a complex internal anatomy of the root canal system. DI type 3 is an anomaly characterized by infolding of enamel and dentin extending into the root apex. This may present difficulties when forming a diagnosis and treatment plan. Many treatment modalities have been presented in case reports for DI type 3, but there is insufficient evidence to recommend a therapy. This case report presents the successful nonsurgical root canal treatment of a maxillary canine with an open apex DI type 3, necrotic pulp, and an associated large periradicular lesion.

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Careful management of fused teeth is essential as abnormal morphology can predispose a tooth to caries and periodontal disease. In this paper, a rare case of successful endodontic management of unilateral mandibular third molar fused to a distomolar is reported. Caries was removed from the tooth complex under local anaesthesia. The pulp chambers of the third molar and supernumerary tooth were accessed and the root canals were prepared using rotary instrumentation and copious irrigation with 2.5% sodium hypochlorite. Obturation using the lateral condensation technique with gutta-percha and AH26 sealer was subsequently performed. A 1-year recall showed a good treatment result.

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INTRODUCTION: The purpose of this in vitro study was to assess the apical microleakage of AH26 sealer when three different root canal irrigant regimens were used. MATERIALS AND METHODS: Eighty single-rooted human teeth were randomly divided into three experimental (n=20) and two control groups (n=10). NaOCl was used as irrigant during instrumentation, and apical patency was ensured in all teeth. Final irrigation was implemented as follow: group A- 17% EDTA + 5.25% NaOCl, Group B- 7% citric acid + 5.25% NaOCl, and group C- 20% citric acid + 5.25% NaOCl. The experimental and negative control groups were obturated by laterally condensed gutta-percha with AH26 sealer. The positive control group was obturated without sealer. The teeth were stored in 100% humidity and 37ºC for 48 hours. In the experimental groups and positive control group, the root surfaces except for the apical 2 mm were covered with nail polish and sticky wax. In the negative control group, the roots were completely covered. The samples were then immersed in 2% methylene blue dye for 72 hours at 37ºC. After that the roots were sectioned longitudinally and the dye penetration was measured. The results were statistically analyzed by One-way Variance and Post Hoc Tukey tests. RESULTS: Statistically significant difference was found between groups (P<0.05). Group C showed the least (1.072 mm) and group A showed the most (2.072 mm) amount of dye penetration. CONCLUSION: When a resin-based sealer is used for the obturation of the root canal system, it is better to use a citric acid irrigant instead of EDTA to remove the smear layer and to improve the apical seal.