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Background: A comprehensive understanding of the root form and canal anatomy is essential for successful endodontic treatment. This study aimed to evaluate the root canal anatomy of mandibular premolars in the Pakistani population using cone beam computed tomography (CBCT) and to classify the findings with the new classification proposed by Ahmed et al. METHODS: Ethical exemption was obtained from Aga Khan University Hospital, Karachi. A total of 707 CBCT scans from Karachi and Lahore were included, comprising 592 scans from a tertiary care hospital in Karachi and 115 scans from a radiology center in Lahore. The study focused on sound, fully formed mandibular first and second premolars, excluding those with significant caries, restorations, or prior root canal treatments. Scans from different equipment were used, and calibration was achieved between a specialist endodontist and two dental residents. Data was analyzed using the Statistical Package for the Social Sciences (SPSS) software, version 26. Descriptive statistics, Chi-square tests to determine association between the variables, and a significance level set at 5% (p <0.05) were utilized., Results: A total of 2403 mandibular premolars were analyzed. The most common configuration was 1 MPM 1 (82.90%), with rare variations such as 1 MPM 1-3-1 (0.04%) and 2 MPM 1 B1 L2 (0.04%). Single-rooted premolars were predominant (98.87%), and no significant differences were observed when data was stratified by age or gender., Conclusions: This is the first study in Pakistan involving multiple centers and using the classification system by Ahmed et al. to understand the anatomy of mandibular premolars. The findings indicate that while most premolars have a single root and canal, variations exist. These variations highlight the importance of understanding canal morphology for improving the success of endodontic treatment. Future studies should include a larger and more diverse dataset to fully represent the Pakistani population., Competing Interests: Declarations. Ethics approval and consent to participate: This study has been conducted in accordance with the guidelines of the Declaration of Helsinki. Additionally, Ethical exemption (reference no. 2024–10008-29535) was obtained from the Ethical Review Committee at the Aga Khan University before initiating the study. The Ethical Review Committee of Aga Khan University, Karachi waived the informed consent procedure because the study is retrospective in nature. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

The mandibular premolars can pose a significant challenge in root canal treatment due to their complex canal system. This study investigated the prevalence of multiple roots and complex canal morphology of mandibular premolars in a selected Egyptian sub-population using cone beam computed tomography (CBCT). 283 CBCT scans (131 males, 152 females, age 18-70) included 1132 mandibular premolars (566 first, and 566 second premolars) were viewed for incidences ofvariation in root numbers and canal configuration according to Vertucci's classification. CBCT images were assessed by two endodontists, data were statistically analyzed using Fisher exact and Chi-square tests. The majority of first premolars (85.7%) exhibited a single root, whereas 14.7% had 2 roots with a significantly higher frequency in males (19.8%) than in females (9.5%) (P < .05). The most prevalent type was type I (57.8%), followed by type V (21.7%), while types II and VII made up only 1%. Types V and III were more prevalent among females, while males had a higher prevalence of types I and IV. In 2.5% of cases, mandibular second premolars were found to have 2 roots, with a higher incidence in males (P < .05). Type I canals were significantly more prevalent (90.8%) than other types, followed by type V (5.3%) (P < .05). A statistically significant gender correlation was found regarding root number and canal configuration. It is not uncommon to find mandibular first premolars with two roots in the southern Egyptian population, particularly in males. These observations may be valuable for dentists who treat Southern Egyptians, in Egypt and other countries., (© 2024. The Author(s).)

Objectives: For constructing an isolated tooth identification system using deep learning, Igarashi et al. (2021) began constructing a learning model as basic research to identify the left and right mandibular first and second premolars. These teeth were chosen for analysis because they are difficult to identify from one another. The learning method itself was proven appropriate but presented low accuracy. Therefore, further improvement in the learning data should increase the accuracy of the model. The study objectives were to modify the learning data and increase the learning model accuracy for enabling the identification of isolated lower premolars., Methods: Static images of the occlusal surface of the premolars made from the dental plaster casts of dental students were used as the training, validation, and test data. A convolutional neural network with 32 hidden layers, AlexNet, convolutional architecture for fast feature embedding, and stochastic gradient descent was used to construct four learning models., Results: The accuracy of the identification model increased using static images of the occlusal surface of the teeth with the adjacent teeth deleted as the training and validation data; however, a learning model that could perfectly identify the teeth could not be realized., Conclusions: Static images of the occlusal surface of the teeth with the adjacent teeth deleted should be used as both training and validation data. The ratio of the numbers of training, validation, and test data should be optimized., Competing Interests: Conflicts of interest The authors declare that no conflicts of interest exist., (Copyright © 2022 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.)

Age estimation is an integral part of forensic medical and dental practice. In many countries, the age threshold of 14 years is set to determine the minimum age for criminal responsibility. In the present study, the authors studied the final maturation of the first (IPM 1 ) and second mandibular premolars (IPM 2 ) by Cameriere maturity index and determined cut-offs at the age threshold of 14 years, and validate on the test sample. Orthopantomograms of 960 healthy south Indian children and sub-adults (480 boys and 480 girls) aged between 10 and 18 were analysed, 640 as training sample and 320 as a test sample. The results of logistic regression analysis with age (1 , IPM 2, and sex as predictor variables on training sample showed that both IPM 1 and IPM 2 significantly related to the legal age of 14 years but not the sex (p = 0.052). A receiver operating characteristic (ROC) curve analysis was performed to evaluate the specific cut-off values of IPM 1 and IPM 2 for predicting 14 years. A cut- off value of IPM 1  < 0.01 and IPM 2  < 0.02 were obtained using the highest Youden index value. Our results on test sample showed that the combined predictor, IPM 1  + IPM 2  < 0.02, showed the highest specificity (97.5% in boys and 92.5% for girls), better post-test probability, 97.2% in boys and 91.9% for girls, and a smaller number of false positives (6.8%). In conclusion, the combination of IPM 1 and IPM 2 could be useful in determining the age of over 14 years in south Indian children., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Aims: To evaluate the prevalence, correlation, and differences of C-shaped canal morphology in mandibular premolars and molars by means of cone-beam computed tomography (CBCT)., Materials and Methods: A total of 1433 mandibular premolars and molars CBCT scans from the Saudi population were evaluated. Axial sections of the roots were acquired at coronal, middle, and apical levels to evaluate C-shaped canals types. The prevalence, correlation, differences of C-shaped canals, bilateral/unilateral presence, gender differences, and location of external grooves on roots were assessed., Results: The prevalence of C-shaped canals in the first premolars was 1.5%, 0.80% in second premolars and 7.9% in second molars, whereas C-shaped canals were absent in first molars. No correlation was found between the presence of C-shaped canals within premolars and molars and between the two groups in the same individual. Both premolars and molars exhibited different types of C-shaped canals, C2 being predominant in premolars and C3 in second molars. Longitudinal external grooves were mostly located on mesiolingual (ML) surface in premolars and lingual in molars. Females showed more prevalence of C-shaped canals in second molars and no differences in premolars. Bilateral symmetry and unilateral presence in premolars and second molars were not significant., Conclusions: Although the prevalence of C-shaped canals is significantly higher in mandibular second molars, they are also found in mandibular premolars but in small percentages. No significant differences were found between both genders and both sides. Since they exhibit unpredictable morphology and differences across the root length, the use of small field CBCT is recommended when such anatomy is presented in a tooth indicated for root canal treatment for better management., Competing Interests: None

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.

Background: Teeth may have additional roots and a different number of root canals. Overlooked root canals may cause endodontic failure. The aim of this study was to investigate the prevalence of root canals and the number of roots of premolars in a selected Turkish population. Materials and methods: A total of 2,570 teeth from 1,438 patients were evaluated. The cone-beam computed tomography scans of 1,055 maxillary and 1,515 mandibular premolars were examined. Results: Type IV root canal morphology was observed most frequently in maxillary first premolars (77%), and the rates of single and double channel formations were very similar (51% and 49%, respectively). Of the second maxillary premolars, 57.4% had Type I morphology, and 89.9% of the teeth were single-rooted, while 68.6% had a single root canal. The most common formation was Type I (85%) among mandibular first premolars, and a single root was observed in 95.6% of these teeth. In addition, 87% of the mandibular first premolars had a single root canal. The second mandibular premolars mostly had Type I (95.4%) formation, and 99.3% of the teeth were single-rooted, while 96.9% had a single root canal. Conclusion: According to our findings, 51% of maxillary first premolars had a single root, 79.4% had two root canals, and 77% had Type IV (77%) formation. Maxillary second premolars mostly had Type I formation. In addition, a single root and single root canal formation were most common. Mandibular first premolars generally had a single root and single root canal formation, but 13% had two root canals, and 6.4% had Type V formation. More than 95% of mandibular second premolars had Type I formation. [ABSTRACT FROM AUTHOR]

Aim To describe morphometric aspects of the internal anatomy of C-shaped mandibular premolars from a Brazilian subpopulation using micro- CT analysis. Methodology First mandibular premolars with radicular grooves ( n = 123) were scanned using a micro-computed tomography system. After cross-section analysis, 83 specimens were identified with a C-shaped canal and selected for micro- CT analysis. Number and location of canals according to Vertucci's classification, distances between anatomic landmarks, occurrence of apical deltas, furcation canals, prevalence of C-shaped cross-sections at five levels as well as 2-dimensional analysis (Area, perimeter, roundness, aspect ratio, major and minor diameters) were performed for the more prevalent anatomical features. Data were compared statistically using Kruskal-Wallis tests (α = 0.05). Results The more prevalent anatomical types according to Vertucci's classification were Type I (13%), III (8%), V (37%) and VII (2%). Mean distances from the furcation to the cemento-enamel junction were in the range of 5.36-5.65 mm. Apical deltas and furcation canals were present in 36 (43%) and 27 (33%) specimens, respectively. C-shaped cross-sections were more prevalent at the middle (56%) and apical middle levels (81%). Overall, significant differences were found in the 2-dimensional analyses between single canals at the apical third and buccal and lingual canals of Vertucci's V classification ( P < 0.05). Conclusions In this Brazilian subpopulation, C-shaped canal configuration of the root canal system was found in 67% of extracted first mandibular premolars with radicular grooves. Vertucci's types I and V were the most prevalent anatomical variations. C-shaped cross-sections were more prevalent in the middle third, and the presence of apical deltas was the most common feature in the apical third. [ABSTRACT FROM AUTHOR]

Aim. The aim of this study was to evaluate the root canal number and configuration of maxillary and mandibular premolar teeth by gender, intervals for decades, tooth position and unilateral or bilateral occurrence in a Turkish population using Cone Beam Computed Tomography(CBCT) scanning. Methodology. CBCT images of 5496 maxillary and mandibular premolars from 849 patients were evaluated. The following was evaluated in all the images: numbers of roots and root canals, the morphology of the root canal configuration according to the Vertucci classification, male-female differences in the tooth position and male-female differences in unilateral or bilateral occurrence. The reliability data were analyzed with a chi-square test. Results. The most prevalent root canal frequency was the two canals (86.2%) and type IV (76.9%) configuration for maxillary first premolar, one canal (59.7%) and type I (54.5%) canal configuration for second premolar. The incidence of one canal was higher in females and the occurrence of two or three canals was more common in males. The incidence of one canal was higher on the left side of maxillary premolars and the incidence of two canals was higher on the right side. Most mandibular first (93.5%) and second (98.5%) premolars had one canal. In general, females had one root canal of the mandibular premolar, whereas males had two or three canals. The type I configuration was most common and the incidence was higher on the right side. There were some differences found in the frequency distribution of the number of root canals and configuration of maxillary and mandibular premolar teeth according to intervals for decades. Conclusion. CBCT scanning provides comprehensive information about the root canal morphology of maxillary and mandibular premolar teeth. These data may help clinicians in root canal treatment of premolar teeth. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to study the root canal morphology of South Asian Indian mandibular premolars using a tooth clearing technique. Methods Two hundred mandibular premolar teeth were collected from different dental schools and clinics in India. After pulp tissue removal and root canal staining with Indian ink, the specimens were decalcified with 5% nitric acid, dehydrated in ethyl alcohol, and subsequently cleared in methyl salicylate. Results Of the 200 mandibular premolars, 100 were first premolars and 100 were second premolars. Of the first premolars, 94% had a single root, whereas 6% were 2 rooted. Seventy-six percent had a single canal, 22% had 2 canals, and 2% had 3 canals. Eighty-two percent had a single apical foramen, 16% had 2 foramens, and 2% teeth had 3 apical foramens. Eighty percent of teeth had type I, 6% had type II, 10% had type IV, 2% had type V, and 2% teeth had type IX root canal anatomy. Of the 100 second premolars, 92% had a single root, whereas 8% teeth were 2 rooted and fused. Fifty-eight percent of teeth had a single canal, and 42% had two canals. Eighty-eight percent had a single apical foramen, and 12% had 2 foramens. Sixty-six percent had type I, 30% had type II, and 4% had type V root canal anatomy. Conclusions A high prevalence of 2 canals was noted in the first and second premolars. Also, 20% of first premolars and 34% of second premolars had a root canal anatomy other than type I. [ABSTRACT FROM AUTHOR]

Aim To describe unusual variations in the root morphology and root canal systems of mandibular first and second premolar teeth extracted for orthodontic reasons. Normally mandibular first and second premolar teeth have single roots with single canals. A 15-year-old patient presented for orthodontic treatment and two mandibular premolar teeth were examined post-extraction. The mandibular first premolar exhibited three distinct, separate roots and the mandibular second premolar exhibited a C-shaped root canal system. The coronal morphology of each of the mandibular premolars revealed dimensions and anatomy within normal limits. The incidence of a three-rooted mandibular first premolar is approximately 0.2%. Key learning points • Thorough clinical and radiographic interpretation is important in recognizing anomalous root and root canal systems. • The most common forms of root and canal systems and its aberrations must be understood to realize variations from normal do occur. • Successful root canal treatment requires an accurate diagnosis of the root canal system using all available aids. • Value of microcomputed tomography in the study of anatomy ex vivo and cone-beam tomography in clinical endodontics of complex premolar cases is increasing. [ABSTRACT FROM AUTHOR]

Abstract Aim The purpose of this article is to report the case of a mandibular second premolar with four distinct canals. Summary It is generally recognized that incomplete instrumentation and cleaning of root canals will lead to failure in root-treated teeth. Before root canal treatment is performed, the clinician should be aware of the configuration of the pulp space of the tooth that is to be treated. Frequently, root canals are left untreated because the clinician fails to identify their presence, particularly in teeth that have anatomical variations or additional root canals. Traditionally, additional canals have been detected by clinical examination of the floor of the pulp chamber, and sometimes found radiographically. More recently microscopic examination of the pulp chamber using endodontic microscopy has assisted the identification of extra canals. A case report is presented that deals with the successful treatment of a mandibular second premolar with four canals. Key learning points •Even in teeth with a low frequency of abnormal root canal anatomy, the possibility of additional root canals has to be considered in the clinical and radiographic examination of the patient. •The ability to recognize and locate unsuspected canals is enhanced by microscopic investigation of the pulp chamber. [ABSTRACT FROM AUTHOR]