Combination of metformin and double antibiotic paste for the regeneration of non-vital immature teeth: a preliminary randomized clinical study.

BACKGROUND: The present study aimed to investigate whether incorporating metformin in double antibiotic paste (DAP) can promote the regeneration process of non-vital immature teeth. METHODS: Out of 32 pediatric patients undergoing regenerative endodontic procedures (REPs), 6 cases with a follow-up period of less than 12 months or lack of documentation were excluded then the remaining 26 were analyzed. 15 cases received DAP, and 11 cases received a DAP + metformin as the intra-canal medicament, kept for an average of 23 days. During 18 months of follow-up, clinical and radiographic examinations were performed to evaluate the treatment outcomes based on the resolution of apical periodontitis, root development, and the occurrence of intracanal calcification. The chi-square test was used for the statistical analysis (P < 0.05). RESULTS: All patients demonstrated resolution of apical periodontitis; however, complete apical closure was only seen in 50% of the patients. The rate of apical closure and root length was significantly higher in the DAP + metformin group (P = 0.047), although the two groups were not significantly different in terms of root width (P = 0.184). Canal obliteration was seen in 15% of cases, all of which were in the DAP group. CONCLUSIONS: According to the present findings, metformin could promote root development in the regeneration process when incorporated in DAP. TRIAL REGISTRATION: This clinical trial was registered on the Iranian Registry of Clinical Trials (IRCT20200120046197N1) on 26.2.2021.

Evaluation the Solubility and the Porosity of the Nano Fast Cement Comparing to the Mineral Trioxide Aggregate: An in vitro Study.

Statement of the Problem: New calcium silicate base cements are introduced as root repair materials in order to defeat the problems of early root repair materials. Their mechanical properties such as solubility and porosity should be concerned. Purpose: This study was conducted to evaluate the solubility and porosity of the NanoFastCement (NFC) as a new calcium silicate base cement comparing to mineral trioxide aggregate (MTA). Materials and Method: In this in vitro study, scanning electron microscope (SEM) was used to evaluate the porosity at five different magnifications (200×, 1000×, 4000×, 6000× and 10000×) in secondary backscattered electron mode. All analyses were performed at 20kV. The obtained images were subjected to qualitative evaluation regarding the porosity. Solubility was determined following the international standards organization (ISO) 6876 method. Twelve specimens in specially fabricated stainless steel ring molds were weighed, initially and after 24 hour and 28 days of immersion in distilled water. Each weight was measured three times to record the average weight. Solubility was measured by calculating the difference of the initial and final weight. Results: Solubility of the NFC in comparison with MTA showed no statistical difference (p Value > 0.05) after one day and 28 days. NFC acted like MTA and showed an acceptable solubility value at exposure time intervals. In both groups, solubility increased as time went on (p Value<0.05). The porosity of NFC was comparable to MTA, and NFC presented a less porous and a slightly smoother surface compared to MTA. Conclusion: NFC has similar solubility and porosity to Proroot MTA. Therefore, it can be a good, more available and less expensive substitute for MTA.

Maintaining a Hopeless Traumatized Maxillary Central Incisor as a Transient Treatment Option: A Case Report with a 3-Years Follow-Up.

An open apices tooth is among the rare types of traumatic dental injuries is horizontal root fracture. Many factors may affect the treatment and prognosis of root fractures, like the time between trauma and treatment, degree of dislocation and mobility, stage of tooth development, fracture site, and patient's age. This case presents a horizontal root fracture of a maxillary central incisor in an 8-year-old boy. The tooth was considered for extraction due to excessive mobility and deep probing depth, but the patient's parents refused to extract the tooth. After one year, during the follow-up examination, we noticed an unprecedented healing process had been initiated. Due to the weak crown-to-root ratio, the traumatized tooth was splinted to the surrounding teeth to reduce the wrecking forces and promote healing. In a three-year follow-up, the cone-beam computed tomography examination showed that the coronal and apical fragments continued to develop separately. Also, it was observed that the mobility and probing depth were reduced significantly.

Nonsurgical Treatment of Unusual Dens Invaginatus with MTA Based Filler in Immature Maxillary Lateral Incisor: A Case Report.

Dens invaginatus (DI) is a dental anomaly associated with complex internal anatomy. Our article discusses an unusual maxillary lateral incisor with two DI. The treatment was planned and performed using cone-beam computed tomographic (CBCT) imaging. During clinical and radiographic evaluations, tooth #7 was diagnosed with DI and pulp necrosis with asymptomatic apical abscess. Periapical radiographs of the tooth showed 2 roots and complex internal anatomy. CBCT evaluation revealed tooth #7 had 2 separate cul-de-sacs (that separate the main canal into four portions). Root canal treatment was completed in 2 visits. The tooth was obturated with EndoSeal MTA. At the 6-month re-evaluation, the patient remained asymptomatic and his tooth had remained functional. Clinical and radiographic examination showed tooth #7 had no sensitivity to percussion or palpation, probe depths within normal limits (#3 mm), no mobility and continued improvement of periapical lesion, despite the commencement of orthodontic Rx 3months previous. Radiographic assessment at the one-year follow up showed significant osseous healing of the preoperative lesion even after the orthodontic forces.

Assessment of sodium thiosulfate neutralizing effect on micro-hardness of dentin treated with sodium hypochlorite.

BACKGROUND: This study aims to evaluate the ability of sodium thiosulfate (STS) to neutralize the adverse effect of sodium hypochlorite (NaOCl) on dentin micro-hardness. METHODS: Fifty single-rooted teeth were longitudinally sectioned. The samples divided into a control and four sample groups (n = 20). All the samples were immersed in different solutions as follows, Control: Normal saline for 15 min, G1and G2: 2.5% NaOCl for 15 min, G3: 2.5% NaOCl for 15 min, followed by 5% STS for 10 min, G4: Normal saline for 15 min followed by 5% STS for 10 min. All groups except G1 incubated for one week before the test. The micro-hardness of samples was measured. Data were analyzed using the Kruskal-Wallis test for pairwise comparisons. A p value < 0.05 was considered significant. RESULTS: All groups showed a significant decrease in the micro-hardness value compared with the control group. NaOCl for one week (G2) reduced the micro-hardness of dentine compared with samples, tested immediately after immersion in NaOCl (G1) (p < 0.05). NaOCl alone (G2) or treated with STS (G3) resulted in a significant decrease in micro-hardness compared with the STS group (G4) (p < 0.05). CONCLUSIONS: STS as a neutralizing agent could not prevent the dentin micro-hardness downturn caused by NaOCl.

Evaluation of the Antibacterial and Antifungal Effects of ProRoot MTA and Nano-fast Cement: An In Vitro Study.

AIM: One of the most vital characteristics of an ideal root filling material is the capability to inhibit the growth of the microorganisms. Mineral trioxide aggregate (MTA) is one of the most used root repair materials, with approved antibacterial effect. A newly introduced root repair material is nano-fast cement (NFC) which should be investigated. The antibacterial and antifungal activities of NFC were evaluated in the present study. MATERIALS AND METHODS: Enterococcus faecalis (PTCC 1394), Escherichia coli (ATTC 15224), and Candida albicans (PTCC 5027) were employed for the antimicrobial assessment. The following were the steps used to conduct the agar diffusion test (ADT): six agar plates were used. 0.5 McFarland concentration of each strain was cultured on two plates by a sterile cotton-tipped swab. Three holes with 5mm diameter were created on each plate. Freshly mixed cement was placed in the holes of the related plate. After two hours, the plates were incubated at 37°C for 24 hours. Then, the diameter of the growth inhibition zones were measured, and the mean values were used for the analysis. Direct contact test (DCT) was done by using the following steps: Freshly mixed materials were placed in the 96-well microtiter plate. 10 µL of each bacterial suspension was added to the tested cement. After one-hour incubation at 37°C, 245 µL of BHI broth was added to each well, and the plate was vortexed for 2 minutes. About 15 µL of this bacterial suspension was added to a new well which contained 215 µL of fresh medium. The kinetics of the bacterial outgrowth were measured by the microplate spectrophotometer hourly for 12 hours. RESULTS: No significant differences were observed between the diameters of the growth inhibition zones of MTA and NFC groups in ADT. In DCT, the MTA inhibits E. coli more effectively than NFC (p value < 0.001). Both cements had the same inhibitory effect on E. faecalis and C. albicans. CONCLUSION: The MTA and NFC are almost equally effective against the tested microorganisms. CLINICAL SIGNIFICANCE: The antibacterial characteristic of any dental material is an important matter. As well, the antibacterial efficacy of the NFC should be evaluated.

Postendodontic Pain after Pulpotomy or Root Canal Treatment in Mature Teeth with Carious Pulp Exposure: A Multicenter Randomized Controlled Trial.

This equivalence, randomized, clinical trial aimed to compare the postoperative pain of root canal therapy (RCT) with pulpotomy with mineral trioxide aggregate (PMTA) or calcium-enriched mixture (PCEM) in permanent mature teeth. In seven academic centers, 550 cariously exposed pulps were included and randomly allocated into PMTA (n = 188), PCEM (n = 194), or RCT (n = 168) arms. Preoperative "Pain Intensity" (PI) on Numerical Rating Scale and postoperative PIs until day 7 were recorded. Patients' demographic and pre-/intra-/postoperative factors/conditions were recorded/analysed. The arms were homogeneous in terms of demographics. The mean preoperative PIs were similar (P=0.998), the mean sum PIs recorded during 10 postoperative intervals were comparable (P=0.939), and the trend/changes in pain relief were parallel (P=0.821) in all study arms. The incidences of preoperative moderate-severe pain in RCT, PMTA, and PCEM arms were 56.5%, 55.7%, and 56.7%, which after 24 hours considerably decreased to 13.1%, 10.6%, and 12.9%, respectively (P=0.578). The time span of endodontic procedures was statistically different; RCT = 69.73, PMTA = 35.37, and PCEM = 33.62 minutes (P < 0.001). Patients with greater preoperative pain, symptomatic apical periodontitis, or presence of PDL widening suffered more pain (P=0.002, 0.035, and 0.023, resp.); however, other pre-/intra-/postoperative factors/conditions were comparable. Pulpotomy with MTA/CEM and RCT demonstrate comparable and effective postoperative pain relief.

Histological Evaluation of Periapical Tissues after Root Canal Treatment with or without Coronal Seal in Dogs for Six Months.

Introduction: Preventing recontamination of the obturated root canal is important for successful root canal treatment (RCT). The main purpose of this study was assessing the histological health of periradicular tissue in obturated root canals with or without coronal seal between two and six months. Methods and Materials: Sixty roots from five dogs with vital pulps were randomly assigned to one of the following five groups (n=12): Group 1, RCT and six months oral exposure; Group 2, RCT and immediate amalgam restoration; Group 3, RCT and amalgam restoration after two months exposure to the oral cavity; Group 4, RCT and amalgam restoration after four months exposure to the oral cavity; Group 5, RCT with two months exposure to oral cavity. The teeth were prepared and filled with gutta-percha and sealer using lateral condensation technique. Two intact root canals of each animal were regarded as the negative control group (n=10), and the two root canals exposed to the oral cavity constituted the positive one (n=10). After six months the animals were euthanized. The upper and lower jaws were removed and submitted for histological processing. Longitudinal sections were obtained from each root. After staining the sections, periradicular regions were examined histologically under light microscope. The Kruskal-Wallis and Mann-Whitney tests was used to analyze the data (P<0.05). Results: The results showed a significant difference between all groups (P<0.05). The negative control group was free of any inflammation. Two-by-two comparison revealed that the positive control group, Group 1 and Group 4 displayed the most intense inflammation. Groups 2, 3 and 5 showed similar results without developing any significant inflammation. Conclusion: Based upon the findings of this animal study, it can be recommended that the obturated root canals which are exposed to oral cavity for around four months or more should be retreated before crown restoration.

Different Application Methods for Endoseal MTA Sealer: A Comparative Study.

Introduction: The aim of present ex vivo study was to investigate the filling quality and voids, using Endoseal mineral trioxide aggregate (Endoseal MTA) with a single-cone technique with and without ultrasonic application and to compare these methods with lateral compaction technique. Methods and Materials: Thirty-six extracted human anterior single-root teeth were prepared and assigned to 3 groups: Group 1: EMS group was Endoseal MTA+ single-cone; Group 2: EMSU group was Endoseal MTA+ single-cone with ultrasonic activation; and Group 3: LC group was Endoseal MTA+ lateral condensation technique. Teeth were sectioned transversely in coronal, middle and apical of the teeth and the existence of voids and their areas in the slices were measured and scored under a dental microscope. One-way analysis of variance and Post Hoc test were used for statistical analysis and also to detect any significance (α=0.05). Results: EMS group showed significantly more void area than lateral compaction group (P<0.05), but the difference between the EMSU group and the other two groups were not significant (P>0.05). Also, EMS group had significantly higher void score than the other two groups (P<0.017). Conclusion: Endoseal MTA as a premixed calcium silicate sealer has a better performance when used with gutta-percha cone-mediated ultrasonic activation, so we suggest gentle ultrasonic activation for applying Endoseal MTA in the clinical use.

Tooth Discoloration Induced by Imidazolium Based Silver Nanoparticles as an Intracanal Irrigant.

STATEMENT OF THE PROBLEM: The endodontically treated teeth usually suffer from the discoloration induced by endodontic materials, which can adversely affect the esthetical outcome of a treatment. PURPOSE: This study aimed to compare the discoloration caused by the silver nanoparticles coated with imidazolium as an irrigant, sodium hypochlorite (NaOCl), and chlorhexidine gluconate (CHX). MATERIALS AND METHOD: The root tips of 65 single-rooted human teeth were resected and root canal systems were chemomechanically prepared from the apical aspect. The specimens were randomly divided into three experimental (n=15) and two control groups (n=10). In the experimental groups, the substance was placed in the root canal for 30 minutes, and then washed with normal saline. Saline or blood alone was used in the control groups. The discoloration was assessed spectrophotometrically right after substance placement (T1), 1 week (T2), and 1 (T3) and 3 months (T4) after and color change values were calculated. Statistical analysis was performed using multi-sample repeated measures analysis of variance, Tukey's HSD, and Sidak tests. RESULTS: In T1, there was no significant difference in color change between silver nano particle, blood and CHX (p> 0.05); but these three groups had significantly more ∆E value than NaOCl and Normal Saline (p< 0.05). NaOCl and normal saline had no significant difference in T1 (p> 0.05). In T2, T3 and T4 results were the same and showed blood and silver nano particle had significantly higher color change in comparison with NaOCl, CHX and normal saline (p< 0.05). There was no significant difference between NaOCl, CHX, and normal saline in tooth discoloration (p> 0.05). There was no significant difference between silver nano particle and blood in ability of tooth discoloration (p> 0.05). CONCLUSION: Within the limitation of this study, silver nano particle material could not be suggested as an intra-canal irrigant regarding its unfavourable tooth discoloration.

Comparison of the Hemostatic Activity of Quercus persica Jaub. & Spach. (Oak) With Ferric Sulfate in Bony Crypts.

Effective tissue hemostasis in periapical surgical site is important in the procedures. Plants with large amount of tannins may act as a local hemostatic agent. We aimed to compare the hemostatic effect of the extract of Quercus persica with one of the common hemostatic material used in periapical surgery. Six standardized bone holes were prepared in the calvaria of 5 Burgundy rabbits. Two hemostatic medicaments were tested for their hemostatic effect and were compared with control defects: Group 1, cotton pellet soaked in 15.5% ferric sulfate solution; Group 2, cotton pellet soaked in pure ethanolic extract of Q. persica. Bleeding score between the groups was compared. The ferric sulfate group exhibited significantly less bleeding than the other 2 groups. Q. persica was found to cause more hemostasis than the control group at 4 and 5 minutes but there were no significant differences between normal saline and Q. persica extract in bleeding control.

Clinical and Histopathologic Investigation of Periapical Actinomycosis with Cutaneous Lesion: a Case Report.

Management of an extra-radicular infection is a challenging procedure that requires surgical intervention. This report describes a patient with discharging cutaneous lesion that required apical surgery. A 40-year-old woman was referred to the Department of Endodontics, Shiraz Dental School with chief complaint of a cutaneous sinus tract. She had been treated by a dermatologist and an otolaryngologist. The patient had also received orthograde root canal treatment of tooth #16. Yet, the lesion was still discharging and the patient was scheduled for surgery. Histopathologic analysis of the lesion showed actinomycosis infection. A 36-month follow-up revealed clinical and radiographic healing.

Assessment of Root Perforation within Simulated Internal Resorption Cavities Using Cone-beam Computed Tomography.

INTRODUCTION: Internal root resorption lesions may perforate external root surfaces, which may not be detectable on conventional radiographic images. The purpose of this study was to evaluate the accuracy of cone-beam computed tomographic (CBCT) imaging in the detection of small perforations within simulated internal resorption cavities. METHODS: Artificial internal root resorption cavities with minimal (0.1-0.2 mm) wall thickness were prepared at 64 sites on buccal and lingual halves of 32 single-rooted mandibular teeth that had been split mesiodistally. Perforations with 0.5-mm diameters were produced using a #40 K-file in half of the specimens. All teeth were placed in dry sheep mandibles and imaged using a NewTomVGi CBCT scanner (6 × 6 cm field of view, 0.1-mm resolution; NewTomQR srl, Verona, Italy). Two observers evaluated the images. Interexaminer and intraexaminer agreement were assessed using the kappa statistic. Sensitivity, specificity, and predictive values were used to assess diagnostic accuracy. RESULTS: Intra- and interobserver agreement on perforation detection were high. The sensitivity and specificity of CBCT-based detection of perforation in internal root resorption were 81.3% and 84.4%, respectively. CONCLUSIONS: CBCT imaging is useful for perforation detection in internal root resorption defects.

The long-term effect of calcium hydroxide, calcium-enriched mixture cement and mineral trioxide aggregate on dentin strength.

INTRODUCTION: Many of highly-alkaline dental materials have some adverse effects on physical properties of dentin. As basic substances, mineral trioxide aggregate (MTA), calcium hydroxide (CH) and the new endodontic material, calcium-enriched mixture (CEM) cement, may adversely affect dentin. The purpose of this in vitro study was to evaluate the effect of long-term application of CEM cement, MTA and CH on flexural strength of bovine dentin. MATERIALS AND METHODS: Three hundred and twenty bovine dentin samples were divided into 4 groups, which were either exposed to CEM cement, CH, MTA or normal saline (control group). Samples of each group were divided into 4 subgroups which were tested by means of Instron Universal Testing Machine for periods of 7, 30, 180 and 365 days after exposure to the test materials. The required force for sample breakage was recorded. The data were analyzed by the two-way ANOVA and Tukey tests. RESULTS: The mean value of forces to break the samples in CEM cement and CH groups was significantly lower than the control group after 1 month (P<0.05). After 180 days, the samples of CEM cement group retrieved their strength but in MTA and CH groups the time interval weakened the samples. After one year of exposure to CH and MTA, flexural strength of the dentin reduced to 72% and 38.7%, respectively (P<0.05). Yet the flexural strength of samples in CEM cement group did not change significantly compared to control group. CONCLUSION: Following 365 days of application of experimental materials to bovine dentin, the CEM cement showed an interesting result and the samples in this group reached their initial strength during the first week of the study but the other materials caused a reduction in dentin strength at the end of the study.

Comparing two methods of education (virtual versus traditional) on learning of Iranian dental students: a post-test only design study.

BACKGROUND: The importance of using technologies such as e-learning in different disciplines is discussed in the literature. Researchers have measured the effectiveness of e-learning in a number of fields.Considering the lack of research on the effectiveness of online learning in dental education particularly in Iran, the advantages of these learning methods and the positive university atmosphere regarding the use of online learning. This study, therefore, aims to compare the effects of two methods of teaching (virtual versus traditional) on student learning. METHODS: This post-test only design study approached 40, fifth year dental students of Shiraz University of Medical Sciences. From this group, 35 students agreed to participate. These students were randomly allocated into two groups, experimental (virtual learning) and comparison (traditional learning). To ensure similarity between groups, we compared GPAs of all participants by the Mann-Whitney U test (P > 0.05). The experimental group received a virtual learning environment courseware package specifically designed for this study, whereas the control group received the same module structured in a traditional lecture form. The virtual learning environment consisted of online and offline materials. Two identical valid, reliable post-tests that consisted of 40 multiple choice questions (MCQs) and 4 essay questions were administered immediately (15 min) after the last session and two months later to assess for knowledge retention. Data were analyzed by SPSS version 20. RESULTS: A comparison of the mean knowledge score of both groups showed that virtual learning was more effective than traditional learning (effect size = 0.69). CONCLUSION: The newly designed virtual learning package is feasible and will result in more effective learning in comparison with lecture-based training. However further studies are needed to generalize the findings of this study.

Comparison of soymilk, powdered milk, Hank's balanced salt solution and tap water on periodontal ligament cell survival.

The purpose of this study was to evaluate the ability of soymilk, powdered milk, and Hank's balanced salt solution (HBSS) to maintain human periodontal ligament (PDL) cell viability in vitro. PDL cells were obtained from extracted healthy third molars and cultured in Dulbecco's modified Eagles medium (DMEM). The cultures were exposed for 1, 2, 4, and 8 h to experimental solutions (tap water served as negative control and DMEM as positive control) at 37°C. The viable cells were then counted using the trypan blue exclusion technique. Data were analyzed by using one-way anova, post hoc Scheffe and two-way anova test. Statistical analysis showed that HBSS, powdered baby formula, and soymilk maintain cell viability equally well in different periods of times. Tap water cannot keep cells viable as well as other solutions. Soymilk and powdered baby formula can be recommended as suitable storage media for avulsed teeth for up to 8 h.

Success rate of nonsurgical endodontic treatment of nonvital teeth with variable periradicular lesions.

INTRODUCTION: Bacterial infection of tooth pulp can progress into periapical diseases. Root canal treatment has been established as the best treatment. In cases of failure, nonsurgical retreatment of teeth is preferred to surgical procedure and extraction. MATERIALS AND METHODS: In this historical cohort study, 104 permanent teeth with apical lesion were treated during 2002-2008. All teeth showed radiographic evidence of periapical lesion varying in size from 1 to >10mm. A total of 55 teeth were treated with initial root canal treatment and 49 teeth required retreatment. Patients were recalled up to ≈7 years. All radiographs were taken by RSV MAC digital imaging set and long cone technique. The presence/absence of signs and symptoms and periapical index scores (PAI) were used for measuring outcome. Teeth were classified as healed (clinical/radiographic absence of signs and symptoms) or diseased (clinical/radiographic presence of signs and symptoms). The data were statistically analyzed using student t-test and Pearson chi-square or fisher's exact test. RESULTS: The rate of complete healing for teeth with initial treatment was 89.7%, and for retreatment group was 85.7%; there was no significant difference. Size of lesions did not significantly affect the treatment outcomes. Success of tooth treatment did not reveal significant correlation with gender and number of roots. CONCLUSION: Orthograde endodontic treatment/retreatment demonstrates favorable outcomes. Thus, nonsurgical endodontic treatment/retreatment should be considered as the first choice in teeth with large periapical lesion.

The effects of short-term calcium hydroxide application on the strength of dentine.

BACKGROUND: Studies have suggested that the long-term exposure of dentin from immature teeth to calcium hydroxide may weaken the dentin but the effects of short-term exposure of dentin from mature teeth have not been reported. The aim of this study was to evaluate the effects of a short term application of calcium hydroxide on the strength of dentine from mature human permanent teeth. MATERIALS AND METHODS: 50 human extracted single rooted disease-free permanent mandibular premolars were chosen. The root canals were prepared with rotary instruments and randomly assigned to two groups. In one group, the root canals were filled with a calcium hydroxide paste. Canals of teeth in the control group were left empty. All teeth were stored in normal saline for 30 days and then coronal third root dentin cylinders were created by removing the crown and apical portions of the teeth. An Instron machine was used to measure the compressive forces needed to break the dentin cylinders and data were analysed using the Student's t-test. RESULTS: The mean compressive force in the calcium hydroxide-filled teeth was significantly lower than that in the control teeth (210.6 +/- 32.3 kg cm(-1) vs 246.2 +/- 29.0 kg cm(-1) respectively, P < 0.001). CONCLUSION: Teeth subjected to 30 days application of calcium hydroxide required less compressive force to break root dentin cylinders. Further studies are necessary to determine whether similar effects would result if impact tests were performed.

Effect of lengthy root canal therapy sessions on temporomandibular joint and masticatory muscles.

BACKGROUND AND AIMS: Trauma is one of the major factors associated with temporomandibular joint disorders (TMD). These disorders result from macro-trauma or micro-trauma. Macro-trauma might be iatrogenic; for example, from intuba-tion procedures, third molar extraction procedures, and lengthy dental appointments. The aim of this study was to evaluate the effect of lengthy root canal therapy (more than 2 hours) on TMJ and its supporting structures. MATERIALS AND METHODS: Eighty patients whose root canal therapy session lasted more than 2 hours were examined for the status of TMJ and masticatory muscles. After one week the second part of the examination was carried out for TMJ problems and pain and tenderness levels of masticatory muscles. Data was analyzed using Wilcoxon statistical test. RESULTS: Women showed more pain compared to men. There was a significant increase in pain in the external acoustic meatus examination one week after root canal therapy. Patients who were treated for their posterior teeth suffered more pain than those who were treated for the anteriors and premolars. Other aspects of the examination were not affected significantly by lengthy root canal therapy. CONCLUSION: Lengthy dental treatments can harm TMJ and masticatory muscles and wide opening of the mouth during such appointments can worsen the situation. Therefore, it is wise to break the appointment into shorter intervals and let the patients rest during treatment to close their mouth to prevent iatrogenic damage to TMJ.

Histological evaluation of the effect of three medicaments; trichloracetic acid, formocresol and mineral trioxide aggregate on pulpotomised teeth of dogs.

The aim of this study was to use clinical, radiographic and histological examinations to compare the dental pulp response in 162 premolar roots of eight dogs when trichloracetic acid (TCA), formocresol, mineral trioxide aggregate (MTA) and zinc oxide eugenol were used as pulpotomy agents. The teeth were divided into four groups. Following pulpotomy, the teeth were restored with amalgam. The animals were sacrificed at 48 h, 2, 4 and 8 weeks (two dogs at each interval). Histological evaluation indicated no cases with necrosis. After 8 weeks follow up, dentine bridge formation was evident in 20%, 50% and 91.7% of formocresol, TCA and MTA cases respectively. The first signs of bridge formation were seen for MTA at 2 weeks and for TCA at 4 weeks. MTA was superior to formocresol and TCA in treating pulps in dogs. However, bridge formation was seen in 50% of TCA cases after 8 weeks which is a desirable finding in pulpotomy procedures.