Apical root canal microbiome associated with primary and posttreatment apical periodontitis: A systematic review.

BACKGROUND: Microorganisms colonizing the apical root canal system are conceivably the ones directly involved with the causation and maintenance of apical periodontitis. OBJECTIVES: This article systematically reviews the reports on the microbiome occurring exclusively at the apical root canal of teeth with primary and posttreatment apical periodontitis. METHODS: The electronic databases PubMed, Embase, Web of Science, Science Direct, and Proquest were searched up to August 2023. Clinical studies using culture and molecular microbiology methods to identify the microbial taxa present exclusively in the apical root canal segment of infected teeth with apical periodontitis were included. Studies were critically assessed using the Joanna Briggs Institute Critical Prevalence Assessment Checklist. RESULTS: From 2277 articles initially detected, 52 were selected for full reading and 21 were eventually included in this review. Of these, molecular methods were used in 19 and culture in 2 studies. Ten studies evaluated primary infections, 8 evaluated posttreatment infections, and 3 included both. Cryopulverization of the apical root specimens was conducted in 11 studies. All studies evaluated the prevalence and diversity of bacteria, and only one also reported on fungi. Overall, the most frequent/abundant bacterial taxa found in the apical canal of primary infections were Pseudoramibacter alactolyticus, Olsenella uli, Fusobacterium species, Streptococcus species, Porphyromonas endodontalis, Prevotella species, Actinomyces species, Parvimonas micra, Treponema denticola, Synergistetes species, and an as-yet uncharacterized taxon. In posttreatment infections, the most prevalent/abundant bacterial taxa included species of Streptococcus, Enterococcus, Fusobacterium, Actinomyces, Pseudoramibacter, Pseudomonas, and Propionibacterium. At the phylum level, Firmicutes was the most represented. The average apical bacterial load ranged from 105 to 106 in primary infections and from 103 to 104 in posttreatment infections. DISCUSSION: Microbial diversity in the apical part of the root canal system was examined encompassing data from both primary and posttreatment infections. Heterogeneity amongst the studies, especially in sample collection and microbial identification methods, is an important limitation that prevented a meta-analysis. CONCLUSIONS: There is a pronounced bacterial diversity in the infected apical canal, with a high interindividual variability. Different microbiome compositions at the species/genus level are observed according to the infection type. REGISTRATION: PROSPERO CRD42021275886.

Ex vivo detection of mandibular incisors' root canal morphology using cone-beam computed tomography with 4 different voxel sizes and micro-computed tomography.

BACKGROUND: In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients' root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors. METHODS: A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 µm. The teeth were then fixed in the tooth sockets of human dry mandibles and scanned by using a CBCT device with 4 different voxel sizes (300, 200, 250, and 125 µm). Four observers detected in blind the root canal morphology of the teeth according to the CBCT images, and the presence or absence of a double root canal system, and the presence or absence of ACs, were scored according to a 5-point scale, respectively. Receiver operating characteristic (ROC) analysis was performed, and DeLong test was used to compare the area under the curve (AUC) values and the micro-CT data was taken as a gold standard. RESULTS: Among 106 sample teeth, 25 specimens with a double root canal system were identified by the micro-CT. ROC curve analysis of the data obtained by the four observers showed that in the detection of double root canal systems, the AUC values ranged from 0.765 to 0.889 for 300 µm voxel size, from 0.877 to 0.926 for 250 µm voxel size, from 0.893 to 0.967 for 200 µm voxel size, and from 0.914 to 0.967 for 125 µm voxel size (all p < 0.01). In general, we observed a trend that the AUC values, sensitivity, and specialty increased with the decrease in the voxel size, and significantly higher AUC values were detected in 125 µm voxel size images. In the detection of ACs, ROC curve analysis showed that among the four observers, the AUC values ranged from 0.554 to 0.639 for 300 µm voxel size, from 0.532 to 0.654 for 250 µm voxel size, from 0.567 to 0.626 for 200 µm voxel size, and from 0.638 to 0.678 for 125 µm voxel size. CBCT images at a voxel size of 125 µm had a weak diagnostic potential (AUC: 0.5-0.7, all p < 0.05) in the detection of AC, with a lower sensitivity ranging from 36.8 to 57.9% and a higher specialty ranging from 73.6 to 98.8%. CONCLUSIONS: CBCT with 300 µm voxel size could only provide moderate diagnostic accuracy in the detection of a double canal system in mandibular incisors. CBCT with a voxel size of 125 µm exhibited high diagnostic value in the detection of double canal systems, while showing low but statistically significant value in the detection of ACs.

Micro-CT assessment of radicular pulp calcifications in extracted maxillary first molar teeth.

OBJECTIVES: The present study aimed to evaluate the frequency, position, and length of radicular pulp calcifications in three-rooted maxillary first molars using micro-computed tomography. MATERIALS AND METHODS: Two hundred three-rooted maxillary first molars were scanned at a pixel size of 10 µm and reconstructed using similar parameters. Three-dimensional models of the mesiobuccal (MB1, MB2, MB3), distobuccal (DB), and palatal (P) canals were qualitatively evaluated for discontinuity in the canal path. Transaxial and sagittal cross-sectional images of the roots were further screened, and the complete obliteration of the canal lumen by pulp calcification was identified when the canal had similar radiodensity to the surrounding dentine. Then, the number, position, and length of the calcifications were recorded for each root. Intra-observer agreement was performed using Cohen's kappa test, while one-way ANOVA and Duncan tests compared the lengths of calcifications among the canals, with α = 5%. RESULTS: Intra-observer agreement was perfect for identification of pulp calcifications (ĸ = 1.0; p = 0.000). MB2 and MB3 canals accounted for the highest percentage frequency of calcifications distributed throughout the canal path. In the MB1, DB, and P canals, they occurred mainly at the apical third. Lengths of calcifications were greater in the MB3 (0.89 ± 0.81 mm) and MB2 (0.82 ± 0.93 mm) canals than in the MB1 (0.39 ± 0.32 mm), DB (0.34 ± 0.22 mm), and P (0.28 ± 0.22 mm) canals (p < 0.05). CONCLUSION: MB2 and MB3 canals accounted for the highest frequency and length of radicular pulp calcifications. In the MB1, DB, and P canals, calcifications occurred mostly at the apical third, while in the MB2 and MB3, most of calcifications were observed at the orifice level and along the canal path. CLINICAL RELEVANCE: In maxillary first molars, radicular pulp calcifications are mainly located at the apical third of the MB1, DB, and P canals, while in the MB2 and MB3 canals, most of them are at the orifice level or along the canal path.

Mandibular incisors with two canals are associated with the presence of the distolingual root in mandibular first molars: a cone-beam computed tomographic study.

BACKGROUND: This study aimed to evaluate the root canal configurations and the association between mandibular first molars and distolingual root (DLR) and mandibular incisors using cone-beam computed tomography (CBCT). METHODS: Mandibular first molars and incisors were evaluated using CBCT images of 150 patients. Mandibular first molars were classified according to the presence or absence of DLR. The curvature of the DLR was evaluated using Schneider's method in buccolingual and mesiodistal orientations. The angle of the mesiolingual-distolingual-distobuccal canal orifices (ML-DL-DB) was evaluated at the pulpal floor level. The mandibular central and lateral incisors were classified as either single canal or two canals. The association between the root canal system of the mandibular first molar and mandibular incisors was evaluated. Data were analyzed using the Chi-square test, Student's t-test, and odds ratios from binary logistic regression. The significance level was set at 5%. RESULTS: The frequency of mandibular first molars with DLR was 27.0% and that of mandibular incisors with two canals was 25.8%. The curvature of the DLR was 37.1° in the buccolingual orientation and 10.4° in the mesiodistal orientation. The angle of ML-DL-DB was 79.0°. The presence of two canal systems in mandibular incisors was associated with the presence of DLR in the mandibular first molar (left central incisors: p = 0.001, odds ratio = 4.25; left lateral incisors: p < 0.001, odds ratio = 3.8; right central incisors: p = 0.003, odds ratio = 3.86; right lateral incisors: p = 0.001, odds ratio = 3.44) but not with the curvature of the DLR or angle of the ML-DL-DB orifice (p > 0.05). CONCLUSIONS: The mandibular first molar showed a high incidence of separate DLRs. It was confirmed that DLR in the mandibular first molar is highly associated with the presence of two-canal system in the mandibular incisors. This association can aid clinicians in successful endodontic treatments.

Comprehensive evaluation of root and root canal morphology of mandibular second molars in a Saudi subpopulation evaluated by cone-beam computed tomography.

BACKGROUND: The study's goal was to use Cone Beam Computed Tomography (CBCT) to assess the root and root canal anatomy of mandibular second molars with C-shaped root canal configurations in residents of the Hail district. The impact of gender and side on the frequency of root canal morphology was considered. METHODS: The sample size for this study was 304 untreated mandibular second molars with completely developed roots on the right and left sides. Using CBCT on the teeth, the root form and canal morphology for each root are based on Vertucci's classification. The occurrence of canals in the shape of a C. The prevalence and resemblance of the left and right sides or men and females were investigated. The Chi-square test was performed to evaluate the findings. RESULTS: Of the 304 mandibular second molars studied, 286 teeth had two roots (94.1%), whilst 13 (4.3%) were C-shaped root canal systems. 77 molars (25.3%) had two canal orifices, 219 (72.0%) had three canal orifices, and six (2.0%) and one (0.3%) had four and five root canal orifices, respectively. Type IV was the most common for mesial root, accounting for 57.7% of the sample (n = 176). For distal root, the most common occurrence was type I, which occurred 282 times (96.60%). The most prevalent root canal morphology was the presence of two canals in the mesial root and one canal in the distal root of teeth with two distinct roots (variant 3). (69.4%). The overall prevalence of C-shaped root canal systems is (4.3%) (n = 13). CONCLUSIONS: The patient's race is an undeniable factor that influences root canal anatomy. The root canal morphology of mandibular second molars revealed significant differences between Saudi subpopulations. The majority of mandibular second molars had two roots and three root canals. When treating these molars, the presence of a C-shaped root canal system must be taken into account.

Radiographic and electronic working length comparison. An in vivo study of three Electronic Apex Locator devices.

The aim of this study is to compare the working length measured with Root ZX (EAL1), Propex II (EAL2) and Endo Analyzer Model 8005 (EAL3) with radiographic measurements during endodontic treatment. Fifty single canal teeth scheduled for endodontic treatment were selected for the study. After endodontic access preparation, pulp chamber was irrigated with 5mL of 5% sodium hypochlorite (NaOCl). The canal was scouted with a size 10 K-file introduced slightly over the apex to verify the canal patency. The working length (WL) was measured using all three EAL devices and radiographically. All measured working lengths were recorded and compared using ANOVA for repeated measures considering the multiple comparison of paired data Least Significant Difference (LSD). The WL mean values for EAL1 were 19.1 ± 1.7 mm; for EAL2 were 19.4 ± 1.7; for EAL3 were 19.4 ± 1.6 and for RG were 19.2 ± 1.7. The Pearson correlation coefficients indicated that the following correlation between electronic devices and radiographic WL: EAL1- 0.986, EAL2- 0.953 and EAL3- 0.931. Considering the mean values compared to radiographic measures, Root ZX gave better results than the other tested EAL devices. Endo Analyzer Model 8005 showed the worst performance.

CBCT evaluation of root canal morphology and anatomical relationship of root of maxillary second premolar to maxillary sinus in a western Chinese population.

BACKGROUND: To evaluate the root anatomy, root canal morphology and the anatomical relationship between the roots and maxillary sinus of maxillary second premolars by CBCT in a western Chinese population. METHODS: A total of 1118 CBCT scans of the maxillary second premolars were collected from West China Hospital of Stomatology, Sichuan University. Information below were measured on axial, coronal and sagittal sections, recorded and evaluated properly: the number of roots and canals, the morphology of canal system classified by Vertucci standard, the inter-orifice distance of canal orifices, the curvature of each canal and the distance from root tip to maxillary sinus floor. RESULTS: Among the 1118 teeth, 94.2% (1053) are single-rooted and 55.1% (616) have one canal. Type I (55.1%) is the commonest root canal morphology followed by Type II (31.9%). The mean inter-orifice distance (IOD) for multi-canal teeth ranging from 2.72 ± 0.32 to 3.41 ± 0.11 mm. Of 1622 canals, 38.8% (630) curvature are mesiodistal and 30.9% (501) are straight canals. The distance from root tip to maxillary sinus floor increased with age and the mean distance of single-rooted ones is 2.47 ± 3.45 mm. CONCLUSIONS: All kinds of canal morphology category can be detected in maxillary second premolars. The IOD might be a predictable factor for root canal morphology. Roots of maxillary second premolars are related to maxillary sinus which should be treated carefully.

Nanosilver gel as an endodontic alternative against Enterococcus faecalis in an in vitro root canal system in Mexican dental specimens.

Nanotechnology has become a research area with promising results for technological innovation. Endodontics can benefit from this field of research by increasing the success rate of the treatment, which currently ranges between 86% and 98% and has varied very little over the years. One of the causes of endodontic treatment failure is based on the presence of Enterococcus faecalis. The objective of this investigation is to evaluate the antibacterial effect of a gel preparation containing silver nanoparticles (Ag-NP) against E. faecalis present in the walls of the root canal. 60 extracted human uniradicular teeth that were instrumented with Wave One Gold (Denstplay/USA) and subsequently contaminated with Enterococcus faecalis. For antibacterial evaluation, intra-canal conducting was placed, and several groups were formed: a) Ag-NP 300 ug/MI gel; b) Ag-NP 500 ug/MI gel; c) Ca (OH) 2 (Ultracal from Ultradent/USA) and the control group. They were incubated at 37°C and a sample was taken every 24 h for 7 days. The Ag-NP gel showed antimicrobial activity against E. faecalis with a value of minimum inhibitory concentration and minimum bactericidal concentration of 300 g/ml and 900 g/ml, respectively. When the Ag-NP gel was used as an intra-canal conducting drug in an in-vitro model, its antimicrobial effect at 300 g/ml and 500 g/ml was equivalent to the action of Ca(OH)2.

Analysis of root canal system of maxillary first and second molars and their correlations by cone beam computed tomography.

BACKGROUND/PURPOSE: Understanding the root canal systems of molars and the association of root canal system in adjacent or contralateral molars is important for dental practice. This study aimed to use cone-beam computed tomography (CBCT) to analyze the morphology similarity of root canal systems in the maxillary first and second molars. METHODS: CBCT images of 1741 maxillary molars in a total of 519 patients were blindly examined to analyze the correlation of root canal systems between maxillary first and second molars as well as the bilateral first and second molars. RESULTS: The most common type in maxillary first molars is 3R4C (3 roots/4 canals), whereas in maxillary second molars is 3R3C.The symmetry in type of root canals in bilateral maxillary first and second molars were 87.36% and 79.85%, respectively. The similarities of root canal system in adjacent maxillary first and second molars were 53.07% (right side) and 52.58% (left side). The concurrence of MB2 canal in bilateral maxillary first molars is 77.8%, and 35.97% in maxillary second molars. In the 110 patients with MB2 canal in bilateral maxillary second molars, the chance of bilateral MB2 canals in their maxillary first molar is almost 100%. CONCLUSION: Maxillary first molars have higher prevalence of 3R4C than second molars. The symmetry in bilateral maxillary molars is higher than the similarity in adjacent maxillary first and second molars. Application of CBCT analysis of root canal system can improve endodontic treatment outcomes. The correlation of root canal system between teeth is useful for genetic linkage.

Mandibular first premolar with five root canals: a case report.

BACKGROUND: Understanding the anatomical morphology of the root canal is key for successful root canal treatment. The aims of this case presentation are to report a unique case of root canal treatment involving five root canals in the mandibular first premolar and to highlight the importance of variation in root canals of mandibular first premolars in clinical practice. CASE PRESENTATION: A 25-year-old male with intermittent pain in relation to the lower right posterior teeth over 3 weeks was diagnosed with symptomatic pulpitis in tooth #44. Four root canals were found, including mesiobuccal, distobuccal-1, distobuccal-2, and distolingual roots, and the Mtwo rotary system was used for root canal preparation. The four root canals were filled after 2 weeks, when a fifth canal was found, located in the buccal cavity. The fifth canal was confirmed to be the mesiolingual root canal by cone beam computed tomography (CBCT) and was found to be curved. After completion of the root canal filling, CBCT was performed, and a three-dimensional root canal image was reconstructed. After 1 week of observation, the tooth was repaired using composite resin filling. CONCLUSIONS: This is the first case presentation of a fifth canal of the mandibular first premolar and advances our understanding of variations in the anatomy of the mandibular first premolar. This case report provides a reference for the treatment of mandibular first premolars.

Prevalence of middle mesial canal and radix entomolaris of mandibular first permanent molars in a western Chinese population: an in vivo cone-beam computed tomographic study.

BACKGROUND: The aim of this study was to investigate the prevalence of the middle mesial canal (MMC) and radix entomolaris (RE) in mandibular first permanent molars in a western Chinese population using cone-beam computed tomography (CBCT). METHODS: A total of 1174 CBCT images of the mandibular first molars were collected from West China Hospital of Stomatology, Sichuan University. The following information was recorded and evaluated: the detection rate and location of the MMC and RE, the curvature of the RE, the canal configuration and bilateral symmetry. RESULTS: The detection rates of the MMC and RE were 3.41 and 25.04%, respectively, as calculated by individuals, and 1.79 and 22.15%, respectively, as calculated by total teeth. The average curvature in the buccolingual (BL) orientation (40.63 ± 14.39°) was significantly larger than that in the mesiodistal (MD) orientation (17.64 ± 7.82°) (p < 0.05). Of 587 patients, 71.72% (421/587) had bilateral symmetry according to the root canal morphology. The prevalence of three-rooted mandibular first molars was higher in males than in females, while the prevalence of two-rooted mandibular first molars was higher in females than in males. CONCLUSIONS: Our results showed that the RE could be detected in almost 1/4 of the western Chinese population; thus, RE detection requires special attention and careful assessment in endodontic treatment.

Frequency of non-single canals in mandibular premolars and correlations with other anatomical variants: an in vivo cone beam computed tomography study.

BACKGROUND: A knowledge regarding anatomical variants is important to achieve success in endodontic treatment. Root canal treatment of mandibular first premolars (PM1 s) is challenging due to the existence of numerous variations in canal configurations, including a C-shaped variant. We aim to determine the frequency and morphologic characteristics of non-single canals of mandibular first (PM1 s) and second (PM2 s) premolars in a Korean population using cone beam computed tomography (CBCT) and to evaluate correlations between non-single canals of PM1 s and other anatomical variants, such as distolingual roots (DLRs) in mandibular first molars (M1 s) and C-shaped canals in mandibular second molars (M2 s). METHODS: A total of 971 PM1 s and 997 PM2 s from 500 patients were examined in vivo by CBCT. Root canal configurations and C-shaped canals were determined in accordance with the Vertucci classification and Fan classification, respectively. The correlation between non-single canals in PM1 s and DLRs in M1 s was evaluated using logistic regression analysis. RESULTS: PM2 s typically had one root (99.89%) with one canal (98.4%). Among PM1 s with non-single canals (21.2%), Vertucci type V (10.9%) and C-shaped (3.7%) canals were prevalent. Among C-shaped PM1 canals, the majority were Vertucci type V (77.8%); a C-shaped configuration (C2) was predominant mostly at the middle and/or apical third of the root. After adjusting for other variables (i.e., sex, age, and side), C-shaped canals in PM1 s was significantly correlated with the presence of DLRs in M1 s (odds ratio = 2.616; 95% confidence interval, 1.257-5.443; p = 0.010). CONCLUSIONS: The presence of C-shaped PM1 canals was positively related to the presence of DLRs in M1 s. Although C-shaped canals in PM1 s are difficult to distinguish, this finding could aid clinicians in predicting C-shaped canal configurations in PM1 s of patients who exhibit DLRs in M1 s.

An original micro-CT study and meta-analysis of the internal and external anatomy of maxillary molars-implications for endodontic treatment.

The aim of this work was to conduct a radiological micro-CT study and meta-analysis to determine the morphological features of the root canal anatomy of the maxillary molars. The radiological study included micro-CT scans of 110 maxillary first molars and 98 maxillary second molars. To identify articles eligible for inclusion in our meta-analysis, PubMed, Embase, and Web of Science were search comprehensively. The following data were extracted: study type (cadaveric, intraoperative or imaging), Vertucci types of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and inter-canal communications. The mesiobuccal root was the most variable with respect to canal configuration, type I being the most common configuration followed by type II and type IV. Type I was the most common canal configuration in the distobuccal and palatal root. Regarding the number of canals in the maxillary first and second molars, one canal was most prevalent in all roots of the three molars, except for the mesiobuccal root of maxillary first molar, in which two canals were most prevalent. The most prevalent number of roots in all maxillary molars was three. Knowledge of endodontic anatomy determines the parameters of root canal treatment and significantly affects the probability of success. It is therefore especially important to know the morphology of the root canal system in order to perform endodontic treatment correctly. Clin. Anat. 31:838-853, 2018. © 2018 Wiley Periodicals, Inc.

Internal and external morphology of mandibular molars: An original micro-CT study and meta-analysis with review of implications for endodontic therapy.

The aim of this radiological micro-CT study and meta-analysis was to determine the morphological features of the root canal anatomy of the mandibular molars. The radiological study included micro-CT scans of 108 mandibular first, 120 mandibular second, and 146 mandibular third molars. For our meta-analysis, an extensive search was conducted through PubMed, Embase, and Web of Science to identify articles eligible for inclusion. Data extracted included investigative method (cadaveric, intraoperative, or imaging), Vertucci type of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and intercanal communications. In the mesial roots of mandibular molars, the most frequent Vertucci type of canal configuration was type IV, except for the mandibular third molar where type I was most common. Type I was most common in the distal root. There were usually two canals in the mesial root and one in the distal root. Two was the most common number of roots, and a third root was most prevalent in Asia. One apical foramen was most common in the distal root and two apical foramina in the mesial root. Intercanal communications were most frequent in the mesial root. Knowledge of the complex anatomy of the mandibular molars can make root canal therapy more likely to succeed. We recommend the use of cone-beam computed tomography before and after endodontic treatment to enable the root anatomy to be accurately described and properly diagnosed, and treatment outcome to be assessed. Clin. Anat. 31:797-811, 2018. © 2018 Wiley Periodicals, Inc.

Laser-based Disinfection of the Root Canal System: An Update.

INTRODUCTION: Microorganisms have been considered to have played a critical role in the initiation and development of pulpo-periapical diseases. Some evidences have shown that mechanical instrumentation may leave considerable portions of canal surfaces undebrided. Therefore, some supplemental methods, such as the use of chemical solutions and/or lasers, have been introduced to further disinfect the complicated canal anatomy and destroy as many microorganisms as possible. The purpose of this review was to address a brief review of characteristics of lasers and their effects to disinfect the root canal in endodontics.

Evaluation of the root and root canal systems of mandibular first premolars in northern Taiwanese patients using cone-beam computed tomography.

BACKGROUND/PURPOSE: Cone-beam computed tomography (CBCT) can provide valuable data for root canal systems of human teeth in vivo. This study used CBCT to evaluate the number of roots and canals of 300 mandibular first premolars in 150 northern Taiwanese patients. METHODS: The root canal systems of 300 mandibular first premolars in 150 northern Taiwanese patients with bilateral premolars were analyzed by CBCT. RESULTS: Of the 300 mandibular first premolars, 197 (65.7%) had one root with one canal (1R1C), 49 (16.3%) had one root with two canals (1R2C), 51 (17.0%) had two roots with one canal in each root (2R2C), and three (1.0%) had three roots with one canal in each root (3R3C). Statistical analyses showed that women had a significantly higher incidence of 1R1C mandibular first premolars (71.4%) than men (58.8%, p = 0.031), and men had a significantly higher incidence of 2R2C mandibular first premolars (27.2%) than women (8.5%, p < 0.001). One hundred and twenty-two (81.3%) of the 150 patients had a symmetrical root and root canal system between the right and left mandibular first premolars. Men had a significantly higher symmetrical rate of 2R2C mandibular first premolars (26.5%) than women (8.2%, p = 0.013). CONCLUSION: Approximately 82% of mandibular first premolars in northern Taiwanese patients have one root with either one or two canals. There are significant differences in the number of roots and canals and symmetry of the root canal system of bilateral mandibular first premolars between male and female northern Taiwanese patients.

Three-dimension model of root canal morphology of primary maxillary incisors by micro-computed tomography study.

The success of root canal treatment for deciduous teeth depends upon the shape of the root canal, among other factors. Despite this, there are limited reports on the use of high-resolution micro-CT to describe the root canal morphology of primary maxillary incisors. In this study, we aimed to create a three-dimensional (3D) digital model of the root canal morphology of primary maxillary incisors using microcomputed tomography (micro-CT). To provide a reference for the development of restorative posts for the primary maxillary incisors. Primary maxillary central and lateral incisors (n = 10 each) were analysed. Micro-computed tomography was used to conduct 3D analyses of the root canal system of the primary maxillary incisors. The canal volume and surface area of the primary maxillary central incisors were larger than those of the primary maxillary lateral incisors. The structural model index value was significantly lower in central incisors. At the cervical level and the interface between the cervical and middle one-third cross-sectional levels, the root canals of the primary maxillary lateral incisors were significantly rounder. The labio-palatal dimension and the diameters of the central incisors at the four different levels were significantly smaller than the diameter of the mesio-distal dimension. The taper of the central and lateral incisors gradually increased from the apical one-third to the cervical one-third in the labio-palatal dimension. The data obtained from the 3D analysis of maxillary incisors in this study will contribute to the design of root canal posts.

Optimized protocol for collecting root canal biofilms for in vitro studies.

Endodontic retreatment is often necessitated by several factors, including the persistence of microorganisms in the root canal system (RCS). Their complex organization in biofilms increases their pathogenic potential, necessitating new disinfection strategies. This study aimed to standardize a new in vitro protocol for collecting biofilm from the RCS. Thirty-four bovine incisors were used in the study, divided into two experimental groups with two collection steps each: (a) biofilm collection protocol and (b) absorbent paper points protocol. Twelve specimens from each group were selected for counting colony-forming units (CFUs), while eight specimens were prepared for scanning electron microscopy (SEM). Two additional specimens served as sterilization controls to ensure that experiments were free of contamination. The coronal region was removed and standardized at 15 mm. After preparation with ProTaper up to F5, the apical foramen was sealed with composite resin, and the roots were stabilized with acrylic resin in 1.5-mL Eppendorf tubes. The specimens were sterilized and inoculated with Enterococcus faecalis NTCT 775 every 24 h for 21 days. After this period, each group underwent biofilm collection protocols, and CFU and scanning electron microscopy (SEM) data were analyzed. The Shapiro-Wilk test was performed to assess the normality of log-transformed data, and the results indicated a normal distribution for all groups, allowing parametric testing. The Levene test was used to evaluate the equality of variances. The proposed biofilm collection method yielded significantly higher CFU counts compared with the absorbent paper points method, particularly when analyzed on a log10 scale. An independent samples t-test confirmed a statistically significant difference between the two methods (p < 0.0001). The proposed protocol achieved an efficiency rate of 95.85 % ± 1.15 %, whereas the absorbent paper points protocol yielded a lower efficiency of 5.46 % ± 1.37 %. Therefore, the biofilm collection protocol proposed in this study proved to be more effective for biofilm removal from the RCS.

The Efficiency of Erbium Lasers in the Removal of Root Canal System and Surface Biofilms: A Systematic Review and Meta-Analysis.

Background: Studies have shown positive effects of erbium lasers in removal of biofilms. A review article was required with quantitative data for confirmation of their effects, but there is still no a comprehensive study reviewing their effects based on the root canal and implant surface. This systematic review and meta-analysis was conducted to evaluate the efficiency of erbium lasers in removal of the root canal system and surface biofilms. Methods: Studies were searched with keywords in databases of PubMed, Scopus, Europe PMC, Cochrane Central, Embase, and Web of Science and screened by referees. Data were included based on mean ± standard deviation and size of control and laser groups. Effect sizes were assessed as standardized mean differences and calculated for each study and for the root and dental surface. Laser characteristics and bacteria were considered as moderators. Results: Nineteen articles in the current study comprised 565 samples (283 control samples and 282 laser samples). The analyses showed the significant effects of erbium lasers on bacterial biofilms on the implant surface [-0.496, 95% confidence interval, CI (-0.720 to -0.273); I2 = 26.94; p = 0.029; Q = 13.28] and root canal [-0.551, 95% CI (-0.656 to -0.445); I2 = 23.89; p = 0.031; Q = 10.46]. Results showed that highest efficiency lasers were obtained at higher wavelengths of 2940 nm, 75-100 mJ energy, and 100-150 µsec and <50-Hz pulses. Conclusions: Erbium lasers can be used to remove biofilms on dental implant surfaces and root canal systems and are safe options for untouchable sites in the root canal.

Prevalence and anatomic associations of middle mesial canals and isthmi in mandibular first molars: A CBCT-based study in a Northern Chinese population.

This study investigated the prevalence of the middle mesial canal (MMC) and isthmus in a northern Chinese subpopulation using cone-beam computed tomography (CBCT). CBCT images of 1060 mandibular first molars (MFMs) were analysed. Data analysis was performed using the chi-square test, t-test, and multiple logistic regression analysis (p < 0.05). The prevalence of MMC and isthmus was 15.2% and 40.6%, respectively. The average dentinal thickness in the danger zone was 1.61 ± 0.14 mm. Patients younger than 40 years were two times more likely to have MMC (odds ratio [OR] = 2.204). Additionally, for every 1 mm reduction in the MB-ML orifice distance, the likelihood of detection of MMC in MFM nearly doubled (OR = 1.738). Furthermore, MFMs with MB-ML isthmus were five times more likely to exhibit MMC than those without it (OR = 4.756). The findings revealed that the prevalence of MMC and isthmus in MFMs is high and suggested that anatomical and demographic variables can serve as valuable indicators for clinicians in anticipating their presence.