Morphometric parameters of dental pulp in immature teeth in a sheep model after mechanical pulp exposure and restoration with reinforced zinc oxide-eugenol.

Background: The aim of the study was to investigate the morphometric parameters of dental pulp in open apices immature teeth in a sheep model after mechanical pulp exposure and restoration with reinforced zinc oxide-eugenol. Materials and Methods: In this experimental study, a total of 12 immature mandibular central incisors from six adult male sheep, weighing 30-40 kg and with the age of 1 year old with Merino race were examined. After anesthesia, the pulps of the teeth in the case group were mechanically exposed and then were restored with reinforced zinc oxide-eugenol and amalgam. In the control group, the teeth remained intact. The animals were sacrificed at intervals of 2, 4, 6, and 8 weeks (E2, E4, E6, and E8) in the case and 2 and 8 weeks (C2 and C8) in the control groups. Then, their teeth were removed with the surrounding supporting tissues and alveolar bones. Tissue processing and staining were done, and the sections were examined under a light microscope. The Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data and compare the changes between the two groups. P < 0.05 was considered statistically significant. Results: In response to mechanical exposure, reparative or tertiary dentin was formed, and its thickness increased during the time of the study. The thickness of the odontoblastic layer in the E4 group was the highest amount. The pulp chamber diameter in the C2 group was significantly larger than the other groups, and the diameter of the apical foramen in the E8 was decreased significantly compared to the controls (P < 0.05). Conclusion: In response to mechanical exposure and restoration with reinforced zinc oxide-eugenol, some morphometric parameters of the dental pulp changed significantly in the sheep model compared to the controls.

Outcomes of root canal therapy or full pulpotomy using two endodontic biomaterials in mature permanent teeth: a randomized controlled trial.

OBJECTIVE: The concept of minimally invasive endodontics recommends less-invasive vital pulp therapy (VPT) modalities over more aggressive traditional endodontic approaches in mature permanent teeth with carious pulp exposure, including irreversible pulpitis (IP) cases. Consequently, VPT needs to be compared with root canal therapy (RCT) in terms of treatment outcomes. This randomized clinical trial compares the results of full pulpotomy using two calcium-silicate cements, i.e., mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement, with RCT in mature permanent teeth. MATERIALS AND METHODS: A total of 157 carious pulp exposure cases in two academic centers with/without established IP were selected/included/randomly appointed to three study arms; (i) RCT (n = 51) as the reference treatment, (ii) pulpotomy with ProRoot MTA (PMTA; n = 55), and (iii) pulpotomy with CEM cement (PCEM; n = 51) as two alternative VPT treatments. Two-year clinical/radiographic results were the outcomes of interest. Data were statistically analyzed through the analysis of variance, chi-square, Fisher exact test, and Kruskal-Wallis. RESULTS: At 2-year recall, 147 teeth were examined (6.4% dropout). All molars, except for one, were clinically functional/symptom-free, and there was no statistical difference between the three study arms (p = 0.653). The radiographic success rates in RCT, PMTA, and PCEM arms were 98%, 100%, and 97.9%, respectively, without statistically significant differences (p = 0.544). CONCLUSION: In the management of mature permanent teeth with/without established IP, all experimental groups exhibited equivalent/comparable results. CLINICAL RELEVANCE: Simple VPT using MTA/CEM can be suggested/recommended as a viable advantageous alternative to RCT for the management of carious pulp exposures with/without sign/symptoms of IP.

Scanning electron microscopic evaluation of the effect of different root-end resection methods in the crack formation in root canals filled with mineral trioxide aggregate or calcium-enriched mixture cement.

Background: There is some concern that root resection may alter the surface features and crack formation of the previously set orthograde material. The aim of this in vitro study was to evaluate the crack formation in orthograde mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) plugs after root resection. Materials and Methods: This in vitro study was conducted on 170 extracted human maxillary anterior teeth. The teeth were randomly divided three experimental (n = 50) and control (n = 20) groups. In Group 1, after root canal treatment, half of the roots were cut with a bur, and the other half with an ultrasonic cutter. In Groups 2 and 3, after the 4-mm CEM and MTA plugs were placed and set, the root ends of half of the samples were cut with a bur and the other half by an ultrasonic cutter. The prevalence of cracks in the dentin and orthograde apical plugs of MTA and CEM was then assessed by scanning electron microscopy. Data were analyzed using the McNemar's, Chi-square, and Fisher's exact tests at P ≤ 0.05 level of significance. Results: In general, the prevalence of crack in dentin in Groups 2 and 3 was significantly higher than in the plug (P < 0.05). There was no significant difference in the prevalence of dentin crack in the studied groups (P > 0.05). The prevalence of crack in dentin was lower when the bur was used to cut off the end of the root, although the difference was not significant. The prevalence of crack in the plug was similar in CEM and MTA. Conclusion: Based on the results of this study, the prevalence of crack in dentin is always significantly higher than its prevalence in the plug, and the prevalence of crack in the plug was similar in CEM and MTA; then, when there is an orthograde access to the root canal and surgery is likely in future, MTA and CEM can be placed in an orthograde technique and it just resects the root during surgery.

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.

Proliferation, odontogenic/osteogenic differentiation, and cytokine production by human stem cells of the apical papilla induced by biomaterials: a comparative study.

INTRODUCTION: Clinical applications of bioactive materials are increasing in biomedical tissue engineering. This study sought to assess the effect of calcium enriched mixture (CEM) cement, Biodentine, mineral trioxide aggregate (MTA), octacalcium phosphate (OCP), and Atlantik on proliferation, odontogenic/osteogenic differentiation, and pro-inflammatory cytokine production by human stem cells of the apical papilla (SCAPs). MATERIALS AND METHODS: Proliferation of SCAPs treated with different biomaterials was evaluated using trypan blue exclusion test and flow cytometry. Differentiation of cells was evaluated using ALP activity, alizarin red staining, and RT-PCR. The expression of genes of pro-inflammatory cytokines was also evaluated using RT-PCR. RESULTS: The SCAPs treated with biomaterials showed significantly higher proliferation, increased ALP activity, higher number of calcified nodules, and up-regulation of genes related to odontogenic/osteogenic markers compared to the control group. The expression of pro-inflammatory cytokines increased in all groups compared to the control group. CONCLUSION: The tested biomaterials could induce odontogenic/osteogenic differentiation in SCAPs. MTA had a greater potential for induction of differentiation of SCAPs to odontoblast-like cells while OCP had higher potential to induce differentiation of SCAPs to osteoblast-like cells (MTA↔ BD↔ CEM↔ Atlantik↔ OCP).

Interaction of intracanal medicaments with apical papilla stem cells: quantitative cytotoxicity assessment by methyl thiazolyl tetrazolium, trypan blue and lactate dehydrogenase.

BACKGROUND: Chemical residues often have cytotoxic effects on the stem cells. This study aimed to assess the cytotoxic effects of intracanal medicaments on stem cells of the apical papilla (SCAPs) using methyl thiazolyl tetrazolium (MTT), trypan blue exclusion (TBE) and lactate dehydrogenase release (LDHR) assays. METHODS: SCAPs were cultured and exposed to 0.125, 0.25, 1, 5 and 10 mg/mL concentrations of modified triple antibiotic paste (mTAP)/distilled water (DW), mTAP/chlorhexidine (CHX), calcium hydroxide(Ca(OH)2)/CHX and Ca(OH)2/DW. Cell viability was quantitatively analyzed using the MTT, LDHR and TBE assays. Data were analyzed using one-way ANOVA and Tukey's test. RESULTS: All three assessment methods yielded the same results. Ca(OH)2/ DW resulted in the highest and mTAP/CHX resulted in the lowest cell viability. In contrast to Ca(OH)2, mTAP decreased cell viability in a dose-dependent manner. Also, addition of CHX to mTAP and Ca(OH)2 increased their cytotoxicity. CONCLUSIONS: In contrast to the proliferative effects of Ca(OH)2, even low concentrations of mTAP have cytotoxic effects on SCAPs.

Bilateral Presence of Two Distobuccal Canals in Maxillary First Molars: A Case Report.

This article describes the diagnosis and treatment of bilaterally maxillary first molars with two canals in their distobuccal roots. A 13-year-old male came to the clinic with a severe pain of tooth #14. In the first session, after access and finding the main canals and the second mesio-buccal (MB2) canal, another canal was noticed in the distobuccal root. All teeth were examined and a severe decay was observed in the left maxillary first molar. After preparing the access cavity, another orifice was found between the palatal and distobuccal canals. The presence of the second distobuccal canal was confirmed using an apex locator and radiography.

Endodontic Treatment of a Maxillary Lateral Incisor with Two Canals: A Case Report.

Variations in the number of roots and canals have been extensively reported in endodontic literature. One rare variation is presence of two separate root canals in maxillary lateral incisors. This study reports a maxillary lateral incisor with two canals. Although rare, knowledge about this anatomical variation can help in successful endodontic treatment of such teeth.

Comparative Evaluation of Root Canal Transportation by Three NiTi Single-File Systems in Curved Canals: A Cone Beam Computed Tomography Study.

INTRODUCTION: This study is aimed at evaluating root canal transportation in the mesiobuccal canal of mandibular first molars prepared with One Shape, Reciproc, and M-One nickel titanium (NiTi) single-file rotary systems using cone beam computed tomography (CBCT). MATERIALS AND METHODS: In this ex vivo study, CBCT scans of 45 extracted human mandibular first molars with 20-40° curvature were obtained. The teeth were randomly divided into three groups (n=15) for preparation of the mesiobuccal canal with One Shape, Reciproc, and M-One rotary systems according to the manufacturers' instructions. CBCT scans were obtained again after canal preparation. Changes caused by preparation in the coronal, middle, and apical thirds were determined on CBCT scans and analyzed using the Kruskal-Wallis test at P ≤ 0.05 level of significance. RESULTS: No significant difference was noted in the amount of canal transportation among the three groups (P > 0.05). M-One caused greater transportation in the apical third compared with Reciproc and One Shape, and One Shape caused greater transportation in the coronal third compared with other groups, although its magnitude was less than 0.3 mm. CONCLUSION: Reciproc, One Shape, and M-One are not significantly different in terms of canal transportation.

Computed tomography evaluation of root canal transportation using ProTaper, Race and Sendoline rotary systems: an ex vivo study.

BACKGROUND: This ex vivo study aimed to compare transportation of the mesiobuccal root canal of mandibular first molars instrumented with ProTaper, Race and Sendoline rotary systems using cone beam computed tomography (CBCT). MATERIALS AND METHODS: Forty-five mesiobuccal canals of mandibular first molars were randomly divided into three groups of 15. Root canals in each group were instrumented with the ProTaper, Race or Sendoline rotary system according to the manufacturers' instructions. Root canal preparations were performed by one operator, while root canal wall measurements were made by another operator blinded to the group allocation of teeth. The pre- and post-chemomechanical preparation CBCT scans were obtained and evaluated at 3, 6 and 9 mm levels from the apex. The amount of root canal transportation at these levels was calculated. Data were analyzed using SPSS version 17 via Mann-Whitney and Kruskal-Wallis tests. P<0.05 was considered significant. RESULTS: No significant difference was noted in canal transportation among the groups (P>0.05), but ProTaper showed the least and Sendoline caused the most canal transportation in the coronal third. CONCLUSION: ProTaper, Race and Sendoline rotary systems are not significantly different in terms of canal transportation. Although all rotary files cause root canal transportation, ProTaper and Race showed the least amount of canal transportation in the coronal and apical thirds, respectively.

Comparison of Coronal Leakage in Tooth Preparation with Two Single File Systems and Three Obturation Techniques.

AIMS AND OBJECTIVES: Root canal preparation and obturation are of great importance in endodontics. Its purpose is to eliminate pulpal and periradicular disease. The aim of this study was to compare coronal bacterial microleakage in prepared root canals using Neoniti A1 and Reciproc files that obturated with lateral compaction, single cone gutta-percha, and hybrid (tapered cone/lateral compaction) methods. MATERIALS AND METHODS: In this ex vivo study, a total of 110 single-rooted mandibular first premolars were choose and randomly divided into two study groups A and B (each 45) that one group was prepared with Reciproc and another with Neoniti A1 and negative and positive control groups (each 10). Each group divided into three subgroups of 15 each and obturated using a single cone, lateral compaction, and hybrid (tapered cone/lateral compaction) techniques. For evaluation of coronal leakage, "two-chamber setup" was used. The solution of enterococcus faecalis culture was injected in the upper chamber and incubated. If the bacteria pass through the canal and obturation materials, the lower chamber becomes turbid. TSB medium in the lower chamber (apex) were investigated every day in terms of occurrence of turbidity, and the duration of occurrence of leakage was recorded. The data were analyzed using Chi-square test. RESULTS: Data analysis showed that in each group the difference in percentages between subgroups was statistically significant (P = 0.003). So that the highest and the lowest amount of leakage in both groups were related to lateral compaction and hybrid techniques, respectively. CONCLUSION: Under the conditions of this study, independent of the instrument used for canal preparation, hybrid method and then single-cone technique, however, were more effective in the prevention of coronal leakage than lateral condensation technique.

Apical Extrusion of Intracanal Bacteria with Single File and Multifile Rotary Instrumentation Systems.

AIMS AND OBJECTIVES: Instrumentation techniques may cause extrusion of microorganisms and their products into the periapical region resulting inflammation and treatment failure. The aim of this ex vivo study was comparing the apical bacterial extrusion in canals prepared with single file versus multiple file rotary systems. MATERIALS AND METHODS: Ninety-two human single-rooted mandibular first premolars were used. Endodontic access cavities were prepared, and root canals were contaminated with an Enterococcus faecalis (E. faecalis) suspension. The samples were incubated at 37°C for 30 days; the contaminated teeth were divided into four groups of 20 specimens each (1: Reciproc, 2: Mtwo, 3: Neoniti A1, 4: Safesider). Six teeth were not infected and each were prepared with one of the above instruments were considered as negative and six teeth which had been previously infected, were used as positive control groups. Extruded bacteria from the apical foramen during instrumentation were collected into vials containing 0.9% NaCl. The microbial samples were taken from the vials and incubated in brain heart agar medium for 24 h. The resulting bacterial titer, in colony-forming units per mL, was determined. The data entered into SPSS 18 software and were analyzed by Kruskal-Wallis and Mann-Whitney U-tests at 0.05 significance level. RESULTS: Mtwo multifile system showed significantly less bacterial extrusion than Safesider (P = 0.015) and Neoniti A1 (P = 0.042) but did not show significant difference with Reciproc system (P = 0.25). CONCLUSIONS: All instrumentation systems extruded bacteria beyond the apical foramen. However, this study showed that Mtwo multifile rotary system extruded fewer bacteria.

Value of CBCT in vertical root fracture detection in endodontically-treated teeth.

BACKGROUND: Vertical root fracture (VRF) is a diagnostic challenge for dentists. Cone-beam computed tomography (CBCT) scans provide accurate three-dimensional images of teeth enabling detection of VRFs. This in-vivo study compared the accuracy of CBCT and exploratory surgery for detection of VRFs in endodontically-treated teeth. METHODS: Forty endodontically-treated teeth of 40 patients with clinical signs and symptoms of VRFs were evaluated. No fracture line was detectable on periapical radiographs. The CBCT scans with limited FOV were obtained of the teeth and inspected separately by a radiologist and two endodontists. Exploratory surgery was performed for all patients as part of their treatment to ensure the presence/absence of VRF (gold standard). RESULTS: The kappa coefficient was 0.71 (95% CI: 0.59 to 0.84). The CBCT scans had 93% sensitivity, 78% specificity and 88% accuracy for detection of VRFs. CONCLUSIONS: The results showed low specificity of CBCT imaging in detecting VRFs in endodontically-treated teeth.

Evaluation of Cytotoxic Effects of Various Endodontic Irrigation Solutions on the Survival of Stem Cell of Human Apical Papilla.

INTRODUCTION: Root canal disinfection is an important step in regenerative endodontic treatments. An ideal irrigating solution must have high antimicrobial activity and minimum cytotoxicity. This study sought to assess the effect of some irrigating solutions on stem cells from the human apical papilla (SCAP) after different periods of exposure. METHODS AND MATERIALS: Stem cells were isolated from immature, impacted mandibular third molars, transferred to 24-well plates, randomly divided into 6 experimental groups and exposed to BioPure MTAD Cleanser, QMix, 17% EDTA, 2% chlorhexidine (CHX), 5.25% sodium hypochlorite (NaOCl), sterile saline and untreated control group. Cytotoxicity of these solutions was assessed after 1, 5 and 15 min of exposure using the methyl thiazol tetrazolium (MTT) assay. Data were statistically analyzed using repeated measures ANOVA. Level of significance was set at 0.05. RESULTS: The mean percentage of viable cells in all experimental groups was significantly different from the control and sterile saline groups at all the time points (P<0.0001). The mean percentage of viable cells significantly decreased over time in NaOCl, QMix, EDTA and MTAD groups, but no significant reduction was noted in CHX group. At all the time points the highest and the lowest cytotoxicity were seen in MTAD and normal saline groups, respectively. Cytotoxicity of the understudy materials from the highest to the lowest was as follows: MTAD>EDTA>QMax=NaOCl>CHX> sterile saline. CONCLUSION: Chlorhexidine had the lowest cytotoxicity compared to EDTA, MTAD, QMix and NaOCl and its cytotoxicity did not change over time compared to other solutions.

Detection of Carious Lesions and Restorations Using Particle Swarm Optimization Algorithm.

Background/Purpose. In terms of the detection of tooth diagnosis, no intelligent detection has been done up till now. Dentists just look at images and then they can detect the diagnosis position in tooth based on their experiences. Using new technologies, scientists will implement detection and repair of tooth diagnosis intelligently. In this paper, we have introduced one intelligent method for detection using particle swarm optimization (PSO) and our mathematical formulation. This method was applied to 2D special images. Using developing of our method, we can detect tooth diagnosis for all of 2D and 3D images. Materials and Methods. In recent years, it is possible to implement intelligent processing of images by high efficiency optimization algorithms in many applications especially for detection of dental caries and restoration without human intervention. In the present work, we explain PSO algorithm with our detection formula for detection of dental caries and restoration. Also image processing helped us to implement our method. And to do so, pictures taken by digital radiography systems of tooth are used. Results and Conclusion. We implement some mathematics formula for fitness of PSO. Our results show that this method can detect dental caries and restoration in digital radiography pictures with the good convergence. In fact, the error rate of this method was 8%, so that it can be implemented for detection of dental caries and restoration. Using some parameters, it is possible that the error rate can be even reduced below 0.5%.

In-vitro evaluation of coronal microbial leakage after post space tooth preparation.

BACKGROUND: The aim of this in-vitro study was to determine the occurrence of coronal microbial leakage in endodontically treated teeth that have been prepared for post space, and also determine the minimum and maximum time required for the permanent restoration of the teeth after post space preparation. METHODS: This experimental study was conducted using a simple random sampling. Fifty extracted single-root teeth with approximately the same length were selected for this study. In order to assimilate the samples length, the crowns of all teeth were cut perpendicular to the long axis of the teeth at a distance of 15 mm from the apex. The canals of 40 teeth were filled with gutta-percha and sealer and prepared for post placement. The teeth were divided randomly into two equal groups of 20 each. In one group, temporary dressing (Cavisol) was used while in the other group, no dressing was used. Five of the teeth were considered as a positive and 5 as a negative control group. For evaluation of microbial leakage, "two-chamber setup" was used. The solution of Proteus mirabilis with fresh culture was injected in the upper chamber and incubated. If the bacteria pass through the dressing and obturation, the trypticase soy broth (TSB) media become turbid. TSB medium in the lower chamber (apex) were investigated every day in terms of occurrence of turbidity and the duration of occurrence of coronal leakage was recorded. The data were analyzed using independent t-test. RESULTS: The leakage time in the group without temporary filling was within 7-21 days and it was within 28-47 days in group with temporary filling (P<0.001). CONCLUSIONS: The minimum time required for microorganisms to enter the canal in group with and without dressing was 28 and 7 days respectively. It is suggested that the teeth with post space preparation receive permanent restoration after RCT in the shortest possible time, to reduce the need for retreatment.

Analysis of methylation and mRNA expression status of FADD and FAS genes in patients with oral squamous cell carcinoma.

BACKGROUND: Apoptosis is an important mechanism that is responsible for the physiological deletion of harmful, damaged, or unwanted cells. Changed expression of apoptosis-related genes may lead to abnormal cell proliferation and finally to tumor genesis. Our aims were to analyze the promoter methylation and gene expression profiles of FADD and FAS genes in risk of OSCC. MATERIAL AND METHODS: we analyze the promoter methylation status of FADD and FAS genes using Methylation - Specific PCR (MSP) in 86 OSCC tissues were kept in paraffin and 68 normal oral tissues applied as control. Also, FADD and FAS genes expression were analyzed in 19 cases and 20 normal specimens by Real-Time Reverse-Transcripts PCR. RESULTS: Aberrant promoter methylation of FADD and FAS genes were detected in 12.79 % (11 of 86) and 60.46 % (52 of 86) of the OSCC cases, respectively, with a significant difference between cases and healthy controls for both FADD and FAS genes (P < 0.001). The gene expression analysis showed statistically significant difference between cases and healthy controls for both FADD (p<0.02) and FAS (p<0.007) genes. CONCLUSIONS: To the best our knowledge, the data of this study are the first report regarding, the effect of promoter hypermethylation of the FADD and FAS genes in development of OSCC. To confirm the data, it is recommended doing further study in large sample sizes in various genetic populations.

Evaluation of the effect of blood contamination on the compressive strength of MTA modified with hydration accelerators.

OBJECTIVES: This study was performed to evaluate the effect of blood contamination on the compressive strength (CS) of Root MTA (RMTA) modified with Calcium chloride (CaCl2) and Disodium hydrogen phosphate (Na2HPO4) as setting accelerators over time. MATERIALS AND METHODS: A total of 110 cylindrical specimens of RMTA were divided into 6 experimental groups as follows: Group1, RMTA; Group 2, RMTA modified with CaCl2 (RMTA-C); Group 3, RMTA modified with Na2HPO4 (RMTA-N); Group 4, RMTA contaminated with blood; Group 5, RMTA-C contaminated with blood; Group 6, RMTA-N contaminated with blood. The CS of specimens in all groups was evaluated after 3 hr, 24 hr, and 1 wk. In the modified groups (groups 2, 3, 5, and 6) the CS of five specimens per group was also evaluated after 1 hr. RESULTS: Blood contamination significantly reduced the CS of all materials at all time intervals (p < 0.05). After 3 hr, the CS of specimens in the RMTA groups (with and without blood contamination) was significantly lower than those in the RMTA-C and RMTA-N groups (p < 0.05). The CS values were not significantly different at the other time intervals. In all groups, the CS of specimens significantly increased over time (p < 0.05). CONCLUSIONS: Blood contamination decreased the CS of both original and accelerated RMTA.