Comparative Evaluation of Canal Transportation and Centering Ratio in Curved Canals: A Study of Cone-beam Computed Tomography and Micro-computed Tomography.

Introduction: This study aimed to compare the accuracy and agreement between cone-beam computed tomography (CBCT) and micro-computed tomography (micro-CT) in the assessment of canal transportation and centering ratio following root canal instrumentation with rotary files. Material and Methods: Twenty mesiobuccal canals of mandibular molars were prepared using the 2Shape sequential rotary system. CBCT and micro-CT scans were performed before and after instrumentation, and the magnitude of transportation and centering ratio were measured. The acceptable transportation was set at ≤0.15 mm. The accuracy and agreement between CBCT and micro-CT were calculated, and the intra-class correlation coefficient (ICC) and kappa coefficient were determined to assess the agreement between the two modalities. Statistical analyses were performed using repeated measures ANOVA. Results: Transportation was detected by both modalities at all distances from the apex after instrumentation. The agreement between CBCT and micro-CT in assessing canal transportation was observed in 80%, 85%, 75%, and 75% of specimens at 1-, 3-, 5-, and 7-mm from the apex, respectively. The ICC for transportation and centering ratio was much lower than 0.75, indicating poor agreement between the modalities. The kappa coefficient did not show acceptable agreement between the methods. Conclusions: CBCT and micro-CT demonstrated poor agreement in assessing canal transportation and centering ratio. Micro-CT remains the preferred modality for in vitro investigations, while CBCT should be limited to clinical settings.

Anesthetic efficacy of supplemental buccal infiltration versus intraligamentary injection in mandibular first and second molars with irreversible pulpitis: a prospective randomized clinical trial.

Background: To compare the anesthetic efficacy of supplemental buccal infiltration (BI) (1.7 ml) versus intraligamentary (IL) injection containing 0.4 ml of 4% articaine with 1:100.000 epinephrine after an inferior alveolar nerve block (IANB) with 1.7 ml 2% lidocaine in the first and second mandibular molars diagnosed with irreversible pulpitis (IP). Methods: One hundred subjects diagnosed with IP of either the mandibular first (n = 50) or second molars (n = 50) and failed profound anesthesia following an IANB were selected. They randomly received either the IL or BI techniques of anesthesia. Pain scores on a 170 mm Heft-Parker visual analog scale were recorded initially, before, and during supplemental injections. Furthermore, pulse rate was measured before and after each supplemental injection. During the access cavity preparation and initial filing, no or mild pain was assumed to indicate anesthetic success. The chi-square test, Mann-Whitney U test, and independent samples t-test were used for the analyses. Results: The overall success rates were 80% in the IL group and 74% in the BI group, with no significant difference (P = 0.63). In the first molars, there was no significant difference between the two techniques (P = 0.088). In the second molars, IL injection resulted in a significantly higher success rate (P = 0.017) than BI. IL injection was statistically more successful (P = 0.034) in the second molars (92%) than in the first molars (68%). However, BI was significantly more successful (P = 0.047) in the first molars (88%) than in the second molars (64%). The mean pulse rate increase was significantly higher in the IL group than in the BI group (P < 0.001). Conclusions: Both the IL and BI techniques were advantageous when used as supplemental injections. However, more favorable outcomes were observed when the second molars received IL injection and the first molars received BI.

The Effect of Low-Level Laser Therapy on the Viability of Human Dental Pulp Stem Cells.

Introduction: This study assessed the effect of low-level laser (LLL) irradiation on the viability of dental pulp stem cells (DPSCs). Methods: In this in vitro experimental study, human DPSCs were purchased from the cell bank of Iranian Genetic Resources and cultured in flasks containing Dulbecco's modified Eagle's medium supplemented with 20% fetal bovine serum (FBS) at 37°C, 5% CO2, and 95% humidity. The cells were stored in semi-confluent form, and the culture medium was refreshed every two days. The cells in the control group were not laser-irradiated, but the cells in the experimental groups were irradiated with 660-nm and 808-nm diode lasers with 4.1 J/cm2 energy density. Cell viability was assessed at baseline and after 24, 48, and 72 hours using the methyl thiazolyl tetrazolium (MTT) assay. The effects of laser irradiation, laser wavelength, and time on the percentage of cell viability were analyzed by two-way ANOVA and Tukey's test. Results: The effects of laser irradiation and its wavelength (P=0.04), time of assessment (P<0.001), and the interaction effect of group and time (P=0.02) on cell viability were significant. Cell viability in 660-nm and 808-nm laser groups at 48 and 72 hours was higher than that of the control group; however, only the difference in cell viability between the 660-nm laser group and the control group at 72 hours was statistically significant (P=0.03). Conclusion: Considering the optimal effect of diode laser irradiation (particularly 660 nm) on the viability of DPSCs, we conclude that it may be suitable for relevant clinical applications.

Evaluation of Antibacterial Effects of Cold Atmospheric Plasma, Calcium Hydroxide, and Triple Antibiotic Paste on Enterococcus faecalis Biofilm in the Root Canal System: An In Vitro Study.

Introduction: One of the essential factors in successful endodontic therapy is the effective cleaning and disinfection of the root canal. This study aimed to determine the effect of cold plasma on infected root canals with Enterococcus faecalis and compare its antibacterial effect with the conventional medicaments in vitro. Methods: Sixty-tree single-root teeth were extracted. Canals were cleaned and shaped. Ten teeth were selected as the negative control randomly. The rest of the teeth were incubated at 37°C for 21 days to form E. faecalis biofilm. The specimens were divided into six groups; each group had 10 teeth. In group 1 (the positive control group of calcium hydroxide and triple antibiotic paste [TAP]), methylcellulose was placed in the root canal; in group 2, calcium hydroxide was placed in the root canal for 12 days; in group 3, 10 mg/mL of TAP was placed in the root canal for 12 days; in group 4, helium/oxygen plasma jet was used for 10 minutes. Group 5 was considered as a positive control of plasma, and group 6 was the negative control. After treatment, F4 Pro-Taper rotary file was used to collect root canal microbial biofilms. Bacterial suspensions were serially diluted, and the percentage of growth reduction for each group was obtained by dividing the logarithm of CFU/mL of each group by CFU/mL of the control of the same group. Results: The CFU/mL of TAP and plasma-treated samples was significantly lower than that of the control groups; however, there were no significant differences between the control group and the samples treated by calcium hydroxide. The most percentage of CFU reduction was in the TAP-treated group compared with plasma and calcium hydroxide-treated groups. Conclusion: The application of cold plasma effectively inhibited the growth of E. faecalis and reduced bacterial biofilm. Also, in the present study, 10 mg/mL of TAP caused the complete elimination of E. faecalis. Calcium hydroxide had the most negligible effect on E. faecalis biofilm elimination.

Comparison of Canal Transportation and Centering Ability of One-G, EdgeGlidePath, and Neolix: A MicroComputed Tomography Study of Curved Root Canals.

AIMS: A glide path is created prior to root canal instrumentation by nickel-titanium (NiTi) rotary files to increase the efficiency and safety of cleaning and shaping. This study aimed to assess root canal transportation in use of different glide path files in curved canals. MATERIALS AND METHODS: 30 sound mesiobuccal root canals of mandibular molars with 20° to 40° curvature were selected and randomly assigned to 3 groups of EdgeGlidePath (EGP, EdgeEndo), One-G (Micro-Mega), and Neolix (Neoniti). The specimens were scanned before and after glide path creation by microcomputed tomography (micro-CT). The pre- and postoperative micro-CT scans were superimposed, and the degree of canal transportation and centering ratio were measured at 1, 3, 5, and 7 mm distances from the apical foramen. Statistical Analysis. The data were analyzed by two-way and one-way ANOVA. RESULTS: The effects of distance from the apical foramen and instrument type and the interaction effect of the two were not significant on the centering ability of the files or canal transportation. CONCLUSION: EdgeGlidePath, One-G, and Neolix files fabricated from the conventional NiTi alloy or heat-treated M-Wire alloy showed similar performance regarding centering ability and canal transportation in glide path preparation in curved canals.

Micro-computed tomography assessment of dentinal microcracks after the preparation of curved root canals with rotary and reciprocal systems.

BACKGROUND: Root canal preparation with nickel-titanium (NiTi) instruments may lead to the formation of microcracks in the root canal wall. Vertical root fractures may initiate from dentinal cracks, and eventually necessitate tooth extraction. OBJECTIVES: This study aimed to assess the effect of the instrumentation of curved root canals of mandibular molars with the 2Shape (2S) sequential rotary, EdgeFile® X1 (EFX1) reciprocating and NeoNiTi (NN) rotational single-file systems on the formation of dentinal microcracks with the use of micro-computed tomography (micro-CT). MATERIAL AND METHODS: Thirty curved mandibular molar root canals were instrumented with the 2S, EFX1 and NN systems (10 in each group). The teeth underwent micro-CT before and after instrumentation. Next, the pre-instrumentation and post-instrumentation cross-sectional images were evaluated and compared for the detection of dentinal microcracks. The number of microcracks in each group was calculated and reported as percentage. The data was analyzed using the McNemar's test with the IBM SPSS Statistics for Windows software, v. 25.0 (α = 0.05). RESULTS: Out of the 29,280 cross-sectional images evaluated in this study, 11.5% showed dentinal microcracks (n = 3,362). On the post-instrumentation images, the frequency percentage of microcracks was 12.0% (n = 585) in the 2S group, 8.8% (n = 402) in the EFX1 group and 13.3% (n = 694) in the NN group. All of the microcracks detected on the post-instrumentation images were also present on the preinstrumentation images and no new microcracks were formed after root canal instrumentation with the aforementioned systems. CONCLUSIONS: Root canal instrumentation with the 2S, EFX1 and NN systems did not result in the formation of new dentinal microcracks.

The efficacy of supplemental intraseptal and buccal infiltration anesthesia in mandibular molars of patients with symptomatic irreversible pulpitis.

OBJECTIVE: The aim of this randomized clinical trial was to compare the success rate of three different anesthetic techniques in mandibular molars with symptomatic irreversible pulpitis. MATERIALS AND METHODS: Ninety patients with symptomatic irreversible pulpitis in mandibular molars randomly received three anesthetic techniques. Group I: an inferior alveolar nerve block (IANB) of 2% lidocaine. Group II: IANB and buccal infiltration (BI) of 4% articaine. Group III: IANB + BI and intraseptal injection of articaine in each mesial and distal papilla. The pain (Heft-Parker visual analog scale (VAS)) and electric pulp tester (EPT) scores were recorded prior to (VAS1, EPT1) and after the injection and during access preparation (VAS2, EPT2). The success of anesthesia was defined as the ability to access the tooth with no or mild pain (VAS ≤ 54). RESULTS: The mean value for VAS2 was significantly less and the mean value for EPT2 was significantly more in groups II and III compared with group I. The success rates for groups I, II, and III were 30.33%, 66.66%, and 80.00% respectively. Also, differences of EPT2, VAS2, and success rates were statistically significant between groups II and III. CONCLUSION: Administration of articaine as a supplemental intraseptal and BI following IANB can be considered a more successful anesthetic technique in mandibular molars with symptomatic irreversible pulpitis compared with the conventional IANB and supplemental BI. CLINICAL RELEVANCE: The addition of an articaine intraseptal injection to IANB+BI technique may result in a significantly higher success rate of pulpal anesthesia in mandibular molars with symptomatic irreversible pulpitis.

In Vitro Cytotoxicity and Setting Time Assessment of Calcium-Enriched Mixture Cement, Retro Mineral Trioxide Aggregate and Mineral Trioxide Aggregate.

INTRODUCTION: The present study sought to evaluate and compare biocompatibility and setting time of Retro mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) and Angelus MTA. METHODS AND MATERIALS: CEM cement, Angelus MTA and Retro MTA were assessed in set and fresh states. Extracts transformed to each cavity of three 24-well plates in which 1×104 cell were seeded into each well 24 h earlier. All specimens were incubated in a humidified incubator with 5% CO2 at 37°C. Mosmann's tetrazolium toxicity (MTT) assay was used to determine in vitro cytotoxicity on L929 mouse fibroblast cell line. Cell viability was determined at 1, 24, and 72 h after exposure. The initial setting time was measured by 113.4 g Gilmore needle testing. Then, final setting times were assessed by the 456.5 g Gilmore needle. Data comparisons were performed using the analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05). RESULTS: All groups in both forms indicated higher cell vitality compared to positive control group (P<0.001). After 24 h, the set Retro MTA showed better biocompatibility compared to set CEM and set Angelus MTA (P<0.001). Retro MTA showed significantly lower initial and final setting time compared to CEM and Angelus MTA (P<0.001). CONCLUSION: Our results indicated the good cell viability values of Retro MTA and relatively short period of setting time. It seems a promising alternative material in clinical situations where accelerated setting is required. However, more clinical and in vivo investigations are needed for a clear decision making.

Correlation between Histological Status of the Pulp and Its Response to Sensibility Tests.

INTRODUCTION: The purpose of this study was to assess the accuracy of sensibility tests by correlating it with histologic pulp condition. METHODS AND MATERIALS: Assessment of clinical signs and symptoms were performed on 65 permanent teeth that were scheduled to be extracted for periodontal, prosthodontic or orthodontic reasons. The normal pulp and reversible pulpitis were considered as treatable tooth conditions while irreversible pulpitis and necrosis were considered as untreatable conditions. The teeth were then extracted and sectioned for histological analysis of dental pulp. Histologic status and classification corresponded to the treatable or untreatable pulp condition. Comparisons between histological treatable and untreatable pulp condition were performed with chi-square analysis for sensibility test responses. The positive predictive value (PPV), negative predictive value (NPV) and accuracy to detect untreatable from treatable pulp condition were calculated for each test. RESULTS: A significant difference was detected in the normal and a sharp lingered response to heat and cold tests. There was significant difference in the negative response to EPT between histological groups. The kappa agreement coefficient between clinical and histological diagnosis of pulp condition was about 0.843 (P<0.001). The accuracy of cold and heat tests and EPT to detect treatable pulp or untreatable pulp states were 78, 74 and 62%, respectively. The sensibility tests diagnosed untreatable pulpitis with a higher probability (NPV=63%-67% -54%, PPV=83%-91% -95% for heat, cold and EPT, respectively). CONCLUSION: Sensibility test results were more likely to diagnose pulpal disease or untreatable pulp conditions. However, to increase the diagnostic accuracy patient history, clinical signs and symptoms and also radiographic findings in conjunction with sensibility tests must be used. The result of this small study demonstrated a good agreement between clinical and histological pulp diagnosis.

Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System -An in vitro study.

Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load.

Immunohistological Evaluation of Revascularized Immature Permanent Necrotic Teeth Treated by Platelet-Rich Plasma: An Animal Investigation.

OBJECTIVE: Pulp regeneration within the root canal of necrotic teeth is considered an ideal treatment to allow for continued root development and recover teeth vitality. This study aims to evaluate the inductive effect of platelet-rich plasma (PRP) on expression of angiogenesis factors and pulpal revascularization of immature necrotic teeth. MATERIALS AND METHODS: In this experimental animal study, we randomly divided 28 immature premolars from two mixed breed dogs into four groups, two experimental, negative and a positive control. Premolars in negative control group were left intact to develop normally. In the positive control and experimental groups, we removed the pulps and induced pulp necrosis, after which the chambers were sealed. Then, we applied the revascularization protocol in the experimental teeth located in the right quadrant. Two months later, the same protocol was applied to the left quadrant. The root canals were disinfected by irrigation with sodium hypochlorite (NaOCl) solution and application a triple antibiotic past. Following the induction of a blood clot (BC) inside the canal space, the coronal portion of the canals was assigned to either of two experimental groups: group 1 [BC+PRP+ mineral trioxide aggregate (MTA)], group 2 (BC+MTA). Access cavities were sealed with a Glass Ionomer. The jaws that held the teeth were processed for histologic analysis of newly formed tissue and immunohistochemical evaluation according to vascular endothelial growth factor (VEGF) and factor VIII expressions in the canals. RESULTS: Histological analysis demonstrated no significant difference in the formation of new vital tissue inside the root canals between groups1 (42.8%) and 2 (43.5%, P>0.05). Based on immunohistochemical evaluation, micro-vessel density (MVD) of the granulation tissues in both groups were similar and were higher compared with the normal pulp. We observed strongly positive expressions of VEGF and factor VIII in the stromal and endothelial cells, with severe intensity after one month. Both factors showed downregulation at three months postoperative. CONCLUSION: PRP could not increase the formation of new vital tissue. The immunohistochemical results showed that VEGF and factor VIII played a pivotal role in the formation of new vessels inside the root canals of immature, non-vital teeth.

Management of Traumatized Permanent Incisors. Revascularization and Delayed Replantation.

This article reports a clinical case of a 9-year-old boy with a traumatic injury to the maxillary central incisors 24 hours after a fall in his schoolyard. The upper left central incisor was avulsed and was kept in saliva for four hours from the moment of trauma until its replantation. The right one was necrotized after one month. We describe successful revascularization treatment of right necrotic immature upper incisor and delayed replantation of left one. After 18 months, radiolucent lesions in the periapical areas of both maxillary central incisors had healed, and root apex development was noted with thickening of the walls in tooth #8.

A case report of maxillary second molar with two palatal root canals and a furcal enamel pearl.

This case report presents an uncommon case of maxillary molar with two palatal root canals and an enamel pearl in the furcation area. The article discusses root canal complexities of maxillary second molars as well as possibility of coexisting anomalies in the region that makes radiographic interpretation difficult and compromises the success of endodontic treatment.