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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 1MPM1 (82.90%), with rare variations such as 1MPM1−3–1 (0.04%) and 2MPM1 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. [ABSTRACT FROM AUTHOR]

Abstract 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

Aim: This study aimed to evaluate the correlation between the presence of two canals in mandibular incisors and multiple canals in mandibular premolars in the Western Uttar Pradesh population of India using cone-beam computed tomography (CBCT). Methods: CBCT scans with 0.125-mm voxel size and 50 mm × 50 mm field of view of 800 patients were evaluated for the parameters; a number of canals, root canal configurations (according to Vertucci’s classification), unilateral/bilateral occurrences, and correlation between presence of two canal configuration in mandibular incisors and multiple canals (>1 canal) in mandibular premolars. The data obtained were subjected to statistical analysis using the SPSS statistical program version 22.0 using the Chi-square test. The significance level was set as 5%. Results: According to the current analysis, the prevalence of mandibular incisors with one canal was 68.1% and two canals were 31.9% whereas in mandibular premolars prevalence of one canal was 71.5%, two canals were 27.2%, and three canals were 1.3%. The incidence of Vertucci type I canal configuration (68.1% mandibular incisors and 71.5% mandibular premolars) was more prevalent than the other types. The incidence of C-shaped canals was 2.6%. The prevalence of bilateral occurrence of the same canal configuration was 16.6%. A positive correlation was found between the presence of two canals in mandibular incisors with multiple canals in mandibular premolars (20.4%). Conclusion: The root canal morphology of mandibular premolar teeth of the Western Uttar Pradesh Indian population is complex. Two canals in mandibular incisors are frequently associated with multiple canals in mandibular premolars.

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. [ABSTRACT FROM AUTHOR]

The study evaluated the spatial position of the mental foramen (MF) using 300 cone‐beam computed tomography. The spatial position was analyzed with the horizontal location and relative location (distance between apical foramen and MF). The horizontal location was assessed through three positions (positions 1, 2, and 3). The relative location was determined with the x, y, and x coordinates of the root apex of mandibular premolars and the MF. Student's t‐test and chi‐square were performed. The most common horizontal location (52%) was position 2, which means between the premolars (p < 0.05). The relative location of the MF to the root apex of the second premolar was closer than the first premolar (p < 0.05). The distance between the root tip of the second premolar and the MF was 5.27 mm, with a minimum value of 1.87 mm. Clinicians should be aware of the possible neural results to the mental nerve of an endodontic infection and the extrusion of irrigation solutions. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to evaluate the correlation between the presence of two canals in mandibular incisors and multiple canals in mandibular premolars in the Western Uttar Pradesh population of India using cone-beam computed tomography (CBCT). Methods: CBCT scans with 0.125-mm voxel size and 50 mm × 50 mm field of view of 800 patients were evaluated for the parameters; a number of canals, root canal configurations (according to Vertucci's classification), unilateral/bilateral occurrences, and correlation between presence of two canal configuration in mandibular incisors and multiple canals (>1 canal) in mandibular premolars. The data obtained were subjected to statistical analysis using the SPSS statistical program version 22.0 using the Chi-square test. The significance level was set as 5%. Results: According to the current analysis, the prevalence of mandibular incisors with one canal was 68.1% and two canals were 31.9% whereas in mandibular premolars prevalence of one canal was 71.5%, two canals were 27.2%, and three canals were 1.3%. The incidence of Vertucci type I canal configuration (68.1% mandibular incisors and 71.5% mandibular premolars) was more prevalent than the other types. The incidence of C-shaped canals was 2.6%. The prevalence of bilateral occurrence of the same canal configuration was 16.6%. A positive correlation was found between the presence of two canals in mandibular incisors with multiple canals in mandibular premolars (20.4%). Conclusion: The root canal morphology of mandibular premolar teeth of the Western Uttar Pradesh Indian population is complex. Two canals in mandibular incisors are frequently associated with multiple canals in mandibular premolars. [ABSTRACT FROM AUTHOR]

INTRODUCTION Mandibular premolars are challenging to treat endodontically due to their varied root and canal morphology, impacting treatment prognosis. This study aimed to assess the root and canal morphology of mandibular premolars in a Nepali subpopulation using Cone Beam Computed Tomography (CBCT) images. MATERIAL AND METHODS A descriptive cross-sectional study was conducted on 348 untreated mandibular first and second premolars teeth of both right and left side having completely developed roots from 87 CBCT images of patients from September 2021-April 2024. The study assessed the number of roots, root canals, their configurations and the tooth length. RESULTS Significant variations in root morphology were observed in mandibular premolars, with most having one root (91.40% in first premolars, 100% in second premolars) and one canal (50% in first premolars, 70.69% in second premolars). Type I configurations were most common (50% in first premolars, 70.69% in second premolars), followed by Type V (21.26% in first premolars, 13.79% in second premolars). C-shaped canals were more frequent in first premolars (2.3%) than second premolars (1.15%). CONCLUSION This study provides valuable insights into root canal morphology variations of mandibular premolars in Nepalese sub population. The findings can help clinicians better understand importance CBCT's in anatomical variations and improve endodontic diagnosis and treatment planning for better outcomes. [ABSTRACT FROM AUTHOR]

Background: The purpose of the study was to investigate the behavior of hard dental structures of the teeth with abfraction lesions when experimental occlusal loads were applied. Methods: A 65-year-old patient came to the dentist because she had painful sensitivity in the temporomandibular joints and the lower right premolars. The patient was examined, and cone-beam computed tomography (CBCT) of the orofacial area was indicated. The data provided from the CBCT were processed with Mimics Innovation Suite 17 software to create the desired anatomical area in 3D format. Then, the structural calculation module was used in order to perform a finite element analysis of the lower right premolar teeth. A focused review of articles published between 2014 and 2023 from specialty literature regarding the FEA of premolars with abfraction lesions was also conducted. Results: The parcel area and the cervical third of the analyzed premolars proved to be the most vulnerable areas under the inclined direction of occlusal loads. The inclined application of experimental loads induced 3–4 times higher maximum shears, stresses, and deformations than the axial application of the same forces. Conclusions: FEA can be used to identify structural deficiencies in teeth with abfractions, a fact that is particularly important during dental treatments to correct occlusal imbalances. [ABSTRACT FROM AUTHOR]

The location of all root canals (RCs) and their adequate preparation, disinfection, and obturation play an important role in successful endodontic treatment (ET). Furthermore, in addition to normal RC system morphology, the operator should also recognize their anatomical variations. This study presented two cases of mandibular premolars with RC configuration Vertucci type II and III after a clinical diagnosis of irreversible pulpitis. RC preparation in two cases was performed using the crown-down technique. After following the standard irrigation protocol, the RCs were obturated using the warm vertical condensation technique. Knowledge of RC system variations, with their preparation and 3D obturation, is the appropriate qualification for ET.

Abstract 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.

INTRODUCTION: The measurement consistency of an assessment tool in biomedical research is important for validation of data. This study aims to determine the reliability of SketchAndCalc™ Area Calculator software in evaluating the obturated surface area of single rooted mandibular premolars and mandibular first molars between two examiners and to compare with the previous studies. MATERIALS AND METHODS: 30 scanning electron microscopy (SEM) images of extracted single rooted mandibular premolars and 30 SEM images of mandibular first molars were obtained from the previous studies. The extracted teeth were previously obturated with GuttaFlow Bioseal. Calibration between two examiners was done prior to start of the study. SketchAndCalc™ Area Calculator software was used to evaluate the volumetric percentage of obturated surface area. Interexaminer reliability was determined between two examiners and compared to the previous studies using Intraclass Correlation Coefficient (ICC) with the following categories; ICC<0.50: poor reliability, ICC 0.50-0.75: moderate reliability, ICC 0.75-0.90: good reliability, ICC>0.9: excellent reliability. The data was analysed with SPSS version 25.0. RESULTS: The ICC values between two examiners were 0.979 in mandibular premolars and 0.918 in mandibular molars. Meanwhile, the ICC values between two examiners and to the previous studies were 0.844 in mandibular premolars and 0.962 in mandibular molars. CONCLUSIONS: Excellent inter-examiner reliability was observed in premolars and molars, however when compared to the previous studies, good and excellent interexaminer reliability were observed in premolars and molars respectively. [ABSTRACT FROM AUTHOR]

Background: Age is the prime factor in the identification of the individual. Among the age estimation methods, dental age estimation from the volume ratios of tooth and pulp is gaining importance due to its accuracy. Objective: To assess the dental age using the ratio of pulp volume (PV) and tooth volume (TV) of extracted mandibular premolars using CBCT and to correlate with chronological age. Methods: Mandibular premolars extracted for orthodontic and periodontic purposes were collected and prepared for CBCT exposure. The data obtained was analyzed using ITK SNAP for manual segmentation. Linear regression analysis was performed separately for the first and second premolars. Pearson's correlation was used to correlate dental age and odontological parameters with chronological age. Results: Statistical analysis of the data yielded the following equation: estimated age = 76.42-817.4*PV/TV of the first premolar and 75.11-758.94*PV/TV of the second premolar. The coefficient of determination (R2) was 0.908 and 0.755, respectively. Conclusion: Predicted age from the volumes of first mandibular premolars is more accurate producing reliable estimates with chronological age.

Introduction: Mandibular premolars are considered an enigma in dentistry because of their variability in anatomical and morphological features making it difficult to treat endodontically. This study was conducted to determine the root and canal morphology of mandibular premolars in the Nepalese population by using cone beam computed tomography imaging. Methods: One hundred and thirty-four cone beam computed tomography images of the Nepalese population were collected by convenience sampling method from April 1 to August 31, 2022 in Bir Hospital, Kathmandu, Nepal. A total of 536 premolars (268 mandibular first premolars and 268 mandibular second premolars) were evaluated by two examiners (one endodontist and one oral radiologist). Canal configuration was classified according to Vertucci’s classification. Results: In mandibular premolar teeth, the majority had one root followed by two roots and fused roots. The most common configuration in mandibular premolars was Vertucci’s type I (83.88% and 96.65% in the first and second premolar respectively) followed by type V (9.89%) in the first premolar and type III (1.86%) in the second premolar. Vertucci’s type VII (0.37%), C-shaped configuration (1.46%), and an unusual configuration (0.37%) were observed in the first premolar. In mandibular first premolars, males showed more variation than females; while in second premolars, females showed more variation than males. Conclusions: Mandibular premolar teeth showed variation in root and canal morphology with one root and Vertucci’s type I in the majority of the cases.

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]

The objective of this paper is to assess the prevalence of a second canal in maxillary and mandibular premolars based on two classification systems of root canal morphology using Cone beam computed tomography (CBCT) images. A total of 286 CBCT scans from the archive of the Radiology department of a hospital were assessed for the presence of a second canal in maxillary and mandibular premolars. The canal configuration and its assessment was undertaken using Vertucci and Ahmed's classification. A Chi-square test was used to test the significance of the difference between gender and age. A total of 286 premolars were examined (217 mandibular premolars and 69 maxillary premolars); of these, 173 teeth (60.5%) were from males and 113 were from females (39.5%). Some 62% of maxillary left first premolars had two roots, followed by maxillary right first premolars (47%), and then maxillary left second premolars (30%) and maxillary right ones (27%), respectively. Type IV Vertucci were seen in maxillary premolars, while type I were ordinarily seen in the included mandibular premolars. Surprisingly, Vertucci type III was only found in mandibular left first premolars at a frequency of 2%. One orifice with two separate canals and two orifices of two distinct canals with two portals of exit were predominantly noticed with maxillary first premolars (2 FP B1 P1) in 73% and 81%, respectively, followed by (1 FP 2) 19%. The prevalence of a second canal in maxillary and mandibular premolars was low in the investigated premolars in comparison to the premolars that had just one root and canal, as assessed based on Vertucci and Ahmed's root canal system classification. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to investigate the root anatomy of the maxillary and mandibular premolars among a sample of the Lebanese population and to explore their incidence by sex and the symmetry between the left and right sides. Materials and Methods: This retrospective analysis of 250 cone-beam computed tomography (CBCT) scans consisted of 960 maxillary and 972 mandibular premolars. Roots, canals, and morphology types were recorded. Vertucci's classification was used to categorize the canal morphologies. Fisher's exact and chi-square tests were applied (P≤.05). Results: The majority of maxillary first premolars had two roots (85.3%) with two canals (91.3%). Most of the maxillary second premolars showed one root (79.8%). Two-root canals (53.55%) were more common than one canal (44.2%). The three-root, three-canal morphology was rarely spotted in the maxillary first (0.4%) and second premolars (2.3%). The one-root (99.2%) and one-canal (84.5%) morphologies were most frequently located in the mandibular first and second premolars (100%, 88.6%), and two canals being less common (15.5%, 11.4%) correct same as before. The total prevalence of premolars with a complex root canal morphology was 62.4%, found in types II, III, and V to VIII. Men had significantly more roots and root canals in their maxillary first premolars than women (P≤.05). No significant differences were observed between the contralateral premolars (P>.05). Conclusions: Premolars displayed wide variations in root and root canal morphology and symmetry between the contralateral premolars. [ABSTRACT FROM AUTHOR]

Introduction: Thorough knowledge of the teeth's root and root canal morphology is vital before obtaining access to endodontic therapy. This study aimed to undertake a comprehensive literature review of the root and root canal anatomy of the mandibular premolars in several provinces of Saudi Arabia. Materials and Methods: The PubMed and Scopus databases were screened for relevant literature. Included studies reported data on the number of roots, root canals, canal configurations, and anatomical variations of mandibular premolars in the Saudi population. Gender morphological differences and bilateral symmetry have also been reviewed, along with case reports of anomalies. Results: Fifteen studies that fulfilled the inclusion criteria were included. The weighted average of single-rooted teeth is 91.4% of the mandibular first premolar and 96.7% of the second premolar. Studies of the internal canal morphology revealed that two or more canals were found in 21.5% of the first premolar and 7.1% of the second premolar. Type I Vertucci canal configuration is the most prevalent in mandibular premolars. The multi-rooted or multi-canalled system variants were frequently reported in the clinical case reports. Conclusion: Mandibular first premolars have a higher incidence of multi-canal system than second premolars, hence clinicians should be attentive to the possibility of an extra canal in these teeth. Few studies are available that discuss the root canal morphology of mandibular premolars in the Saudi population, and further studies with a larger sample size covering Saudi Arabia's provinces are indicated. [ABSTRACT FROM AUTHOR]

Background/Aim: This study aimed to evaluate the root canal morphology of mandibular first and second premolars with the aid of cone-beam computed tomography (CBCT) in the Southeast Anatolian population. Material and Methods: The study examined a total of 1258 mandibular first and second premolars using cone-beam computed tomography images of 370 randomly selected patients who applied to the Department of OralDental and Maxillofacial Radiology of Faculty of Dentistry, Dicle University due to various indications. The total number of roots and root canals, canal symmetry and correlations between the right and left side of the mandible, and the prevalence in men and women were recorded. Data was analzyed using the Chi-Square and Fisher's Exact tests. Canal configurations were evaluated based on the Vertucci classification. Results: The evaluation of CT images of a total of 370 individuals showed that 88.89% of the first premolars and 98.45% of the second premolars were symmetrical. The canal anatomy of the first premolars suggested that 85.98% of the premolars were of Type I, 12.02% were of Type V, and 2% were of Type III based on the Vertucci classification. On the other hand, the canal anatomy of the second premolars revealed that 98.83% were of Type I, 0.67% were of Type V, and 0.5% were of Type III. Conclusions: The prevalent morphology of the multiple canals was Type V, except for the Vertucci classification Type I in the mandibular first premolars. Limited number of canal variations were observed in the mandibular second premolars.

Introduction: Cone-beam computed tomography (CBCT) is a recent advancement in diagnostic radiology in dentistry which allows the clinician to have a clear 3D view of the root canals before starting the endodontic treatment. The goal of the present research was to assess the root canal cross-sectional shape (RCCSS) in maxillary and mandibular premolars in the Saudi Arabian subpopulation. Materials and Methods: In the present study, radiographs of 330 patients who had teeth with complete root development and closed apices were selected. Root canal shapes were assessed at the coronal and middle thirds, and in the apical third, 1 mm above the apical foramen using CBCT. Categorical variables were explained as frequencies and percentages and evaluated using the Chi-square test. Results: 1666 premolars were evaluated in the study. Maxillary first and second premolars were found to have a maximum circular cross-sectional shape at the coronal, middle, and apical sections in most of them followed by flattened and oval cross-sectional shapes except the maxillary right second premolars where the most frequent RCCSS was flattened in the coronal section (71%), circular in the middle (14%), and apical (10%) section. The most recurring coronal RCCSS in mandibular first and second premolars was oval followed by flattened and circular, while the most frequent cross-sectional shape in the middle and apical sections was found to be circular followed by oval and flattened RCCSS. Conclusion: Marked variations were observed in the coronal and middle RCCSS of maxillary and mandibular premolars though the most prominent RCCSS in the apical section was the circular shape.

There is no apical morphological data being available for mandibular first or second premolars in the Turkish population. The aims of the study were (I) to assess apical morphological data of mandibular first and second premolars in a Turkish population at a young-adult age range (II) to analyze potential correlations between the size and position of the apical foramina (AF). Extracted sound teeth were collected from an adult volunteer population as willing to donate. Morphological data were obtained from specimens using a stereomicroscope. The number, size, shape, and position of AF and frequency of accessory foramina were quantified. Mann-Whitney U and Spearman's rank correlation tests were performed (α=0.05). A total of 237 teeth were investigated. The majority of the specimens had one major AF. The frequency of major AF was between 1–3 for both groups. The median AF size in mandibular first and second premolars were 55,180 µm2 and 67,483 µm2, respectively. The majority of foramina shape was irregular for the mandibular first premolars whereas, was oval for the second premolars. The median location of AF with respect to the anatomic apex was 664 µm in mandibular first premolars and 677 µm in mandibular second premolars. The size and location of AF mostly overlap between the mandibular first and second premolars. The shape of the AF might be the only relevant variation concerning the apical morphology between the mandibular first and second premolars in young adults. The interaction between the size and location of AF in mandibular premolars of young adults seems not significant

Purpose: An investigation of the configurations of mandibular premolar roots and canals in a population of Black South Africans. Methods: Cone-beam computed tomography analysis of 772 mandibular premolars was performed, and the premolars were classified according to the systems proposed by Vertucci and Ahmed et al. Root number, canal morphology, age, and sex were recorded. Fisher's exact test was used to determine relationships based on age and sex (P < 0.05). Results: Single roots were seen in the majority of mandibular premolars (97.1%). Single canal configurations (i.e., Vertucci Type 1/Ahmed et al. 1MP1) were observed in 48.5% of first and 81.3% of second mandibular premolars. Mandibular first premolars demonstrated multiple canals in more than half of the sample (51.5%), and C-shaped morphology in more than one-tenth (11.1%). A relationship between sex and the presence of radicular grooves was demonstrated (P = 0.049), males being more likely to demonstrate this feature (P = 0.051). Multiple canals in mandibular first premolars also showed a relationship with sex (P = 0.005), a male predilection being evident (P = 0.007). The Ahmed et al. system proved superior to the Vertucci classification for reporting complex configurations and anatomical variations, although a greater number of unique categories were created. Conclusion: Diverse mandibular premolar root and canal morphology was observed in the studied population. Clinicians must be aware of common morphological features as well as possible anatomical variations in mandibular premolars, as failure to treat complete root canal systems may negatively impact endodontic treatment outcomes. [ABSTRACT FROM AUTHOR]

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. 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. 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. 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. • Identification system for isolated tooth using deep learning were made. • Target teeth were mandible premolars. • Image of the occlusal surface with the adjacent teeth deleted should be used. • Accuracy needs to be further improved. [ABSTRACT FROM AUTHOR]

Objective: To compare the fracture resistance of mandibular premolars restored with mesial-occlusal composites after access with traditional endodontic cavity (TEC) or contracted endodontic cavity (CEC) designs. Materials and Methods: Forty-five virgin single-rooted mandibular premolars were randomly divided into three groups and embedded in acrylic resin moulds. Group I (n = 15) remained untreated. Group II and III were prepared with mesial-occlusal cavities and accessed with TEC or CEC designs. Chambers were irrigated with 5.25% sodium hypochlorite/17% EDTA and dried. After etching and priming with Optibond, access cavities were restored with 3M Filtek. All samples were then fixed in a universal testing machine with the long axis of the roots positioned 45o to a load applied at a crosshead speed of 0.5 mm/min until failure. All specimens were visually assessed for failure modes. Fracture force data was statistically analysed by one-way ANOVA and Tukey post-hoc (P = 0.05). Results: The average fracture force for untreated teeth was 609.7 ± 279.1 N; 601.7 ± 307.9 N for mesial-occlusal cavities with TEC; and 600.9 ± 360.3N for teeth with CEC. There was no significant difference in fracture resistance between groups (F (2,42) = 3.299, P = 0.996). There was no signifi- cant difference in fracture resistance between traditional and modified groups (P = 0.994). All three groups had an equal number of "favourable" (repairable) and "unfavourable" failures (7:8), defined as irreparable failures or root fractures below the level of simulated bone. Conclusions: Modifying access outline to a contracted design did not improve fracture resistance of mandibular premolars restored with mesial-occlusal composites. Clinical Significance: A mandibular premolar with minimal caries that has been accessed endodontically with a CEC or TEC design may be restored provisionally with a class II composite with an equal measure of confidence with regard to fracture resistance. [ABSTRACT FROM AUTHOR]

Background/purpose: Variations in root and root canal morphology of mandibular premolars of Thais has not been reported, and understanding these variations enhances endodontic success. The purpose was to investigate prevalence and morphology of multiple roots, root canals and C-shaped canals in mandibular premolars in a Thai population from cone-bean computed tomography (CBCT) images. Materials and methods: A total of 349 first mandibular premolars and 416 second premolars from CBCT images with 0.125-mm voxel size and 60 × 60 mm field of view were evaluated. Number of roots, root canals, and C-shaped canals were recorded and statistically analyzed using chi-square test. Root canal configurations were defined according to the Vertucci's classification. Levels and distances of separated multiple canals were reported. Results: Multiple roots in mandibular first premolars were found at 5.73% while none of second premolars had. Multiple root canals were found in the first premolars at 19.48% and the second premolars at 3.85%. C-shaped canals (C1/C2) were found in the first premolars at 3.72% and the second premolars at 0.48%. All parameters in the first premolars were significantly higher than in the second premolars (p

Aim: To evaluate the applicability of the method by Lamendin et al. for adult dental age estimation using extracted single-rooted mandibular first premolar in the Western Indian population and to develop a new regression equation. Materials and Methods: Ninety-seven extracted mandibular first premolars were collected from patients in the age range of 15–75 years. The root height, root translucency, and periodontosis parameters were measured. Lamendin's formula was tested on 77 randomly selected specimens. The regression formula was applied to the remaining 20 specimens to validate the same. The data were analyzed using the Interclass Correlation Coefficient (ICC), paired t-tests, and Pearson's correlation tests. Results: The mean estimated age using Lamendin's original formula was 44.75 years (±10.52) for the overall sample (N = 77). There was an overestimation of the age of the study sample by 0.11 year (SD = 11.14; df = 76; P > 0.05). The regression equation based on the data of the mandibular first premolar was Age (Yrs.) =18.423 + 0.441 (P) +0.423 (T) with a SEE = 11.07; r2 = 0.540; Sig. P 0.05) by applying the new premolar formula and Lamendin's original formula, respectively. Conclusion: A strong positive correlation was found between the actual age and the estimated age using Lamendin's method, and there was no significant difference between the actual age and the estimated age of the study population using Lamendin's original and new premolar formula.

Objectives: This study aimed to investigate the anatomy of mandibular premolars from two perspectives—the canal configuration and radicular grooves—using cone-beam computed tomography (CBCT) in a large Korean population. Materials and methods: CBCT images of mandibles acquired from March 2018 to December 2019 for dental treatment were randomly selected. In each image, the root canal of premolars was classified into 8 types according to the canal merging or diverging pattern and the number of apical foramens. The presence and the location of radicular grooves were also assessed. Statistical analysis was performed. Results: A total of 1463 first and 1448 s premolars from 732 patients (390 males, 342 females, mean age of 36.1 years) were evaluated. A single canal with one foramen predominated in both first (85.7%) and second (99.5%) premolars, while complete or partial multi-canals accounted for 14.3% and 0.5% of first and second premolars, respectively. The prevalence of radicular grooves was significantly higher in first premolars (13.2%) than in second premolars (0.5%) and in males (4.3%, n = 119) than in females (2.5%, n = 73). Conclusions: Although most premolars were complete single canals, the first premolars showed a relatively higher number of complex canals compared to the second premolar. In addition, radicular grooves in mandibular premolars were significantly more common in male patients. Clinical relevance: When planning the endodontic treatment of mandibular premolars, clinicians should be aware of their morphologic complexity, especially in the first premolar of male patients. [ABSTRACT FROM AUTHOR]

Background/Aim: The aim of root canal treatment is the thorough cleaning, shaping and obturation of the root canals. Variations in root canal anatomy increase the difficulty of the root canal treatment and therefore the possibility of failure. The mandibular premolars often present complex anatomy and the existence of mandibular second premolars with three root canals is very scarce. This report presents the successful endodontic management of four mandibular second premolars with three root canals.

Abstract 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.

Introduction: Aberrant root canal morphology of mandibular premolars has always been associated with high endodontic treatment failures. This study was conducted to assess the canal morphology of the mandibular premolars in the Malaysian population using periapical radiographs and cross-sections of the premolar teeth. Materials and Methods: One hundred extracted permanent mandibular premolars with intact apex were randomly collected from various clinics across Malaysia. Radiographs were taken both in mesiodistal (MD) and buccolingual (BL) views to examine the presence of a second canal and to evaluate the type of canal configuration. The roots were then stained and perpendicularly resected to the long axis at three levels (cervical, middle, and apical one third). Digital photographs were taken for each of the cross-section sample and analyzed according to the number and shape of canals. Results: It was found that 78% of the mandibular premolars had single canal in BL radiographic view and 65% in MD view. Seventy-one percent of the single-canal premolars were observed in all three cross-sectional views (1-1-1 configuration). Furthermore, 37% showed oval-shaped canals and 34% showed irregular-shaped canals mainly found at cervical one third; 20% of the teeth showed the canals to be rounded in shape, most prevalent at the apical one third. Two canals with isthmus were observed in 5% of the all cross-sectional views. Conclusion: The majority of mandibular premolars in Malaysian population have a single canal, and there are a few possibilities of two or more canals in these teeth.

Objectives: To establish the frequency of the various types of direct contacts of the root apices with the wall of the mandibular canal and to determine gender differences in number of such contacts in a selected Belarusian population using cone beam computed tomography. Methodology: One hundred and two cone beam computed tomography scans were analyzed to classify the types of contact and three-dimensional relationship between the mandibular teeth and the mandibular canal. Results: The direct contact between the teeth and the mandibular canal was observed in 63.7% of patients. Overall 300 roots of 189 teeth were in direct contact with the mandibular canal: 9.3% were second premolars, 14.7% were first molars, 33.8% were second molars and 50.0% were third molars. There were no statistically significant differences in the number of teeth with direct contact with the mandibular canal between males and females. Conclusion: The direct contact of the root apices with the mandibular canal was most often found in the second and third molars. The root apices of the third molars had the greatest variability of location relatively to the mandibular canal.

Objectives: A C-shaped canal can lead to dead spaces being left in the root canal system during endodontic treatment and adversely affect the treatment outcome. The aim of this study was to determine the prevalence of C-shaped premolars and its correlation with gender, right/left side, and family-related variables using cone beam computed tomography (CBCT). Methods: CBCT images of 1721 mandibular premolars (from 563 patients) were examined in serial axial sections for the presence of C-shaped anatomy. Fisher's exact test was carried out to find the relationship between occurrence of the Cshaped canal and gender, location in the mouth, and occurrence of the same in firstdegree family members. Results: Out of the 1721 examined mandibular premolars, C-shaped canals were found in only 21 teeth (1.22%): 15 mandibular first premolars (1.6%) and 6 mandibular second premolars (0.76%). No significant difference was found between the premolars of males and females or between the right and left-side premolars (p > 0.05). However, a significant association was noted between C-shaped mandibular premolars and occurrence of the same in first-degree family members (p = 0.047). Furthermore, both C1 and C2 types were usually located within the middle part of the root, at 42.86% and 57.14%, respectively. Conclusions: Although the prevalence of the C-shaped canal among mandibular premolars is not high, endodontists should be careful when performing root canal treatment and post-placement. The use of CBCT can be helpful in the diagnosis and management of these conditions, especially when the occurrence of the C-shaped mandibular premolar is reported in one of the first-degree relatives of the patient. [ABSTRACT FROM AUTHOR]

Variations in root and root canal morphology of mandibular premolars of Thais has not been reported, and understanding these variations enhances endodontic success. The purpose was to investigate prevalence and morphology of multiple roots, root canals and C-shaped canals in mandibular premolars in a Thai population from cone-bean computed tomography (CBCT) images. A total of 349 first mandibular premolars and 416 second premolars from CBCT images with 0.125-mm voxel size and 60 × 60 mm field of view were evaluated. Number of roots, root canals, and C-shaped canals were recorded and statistically analyzed using chi-square test. Root canal configurations were defined according to the Vertucci's classification. Levels and distances of separated multiple canals were reported. Multiple roots in mandibular first premolars were found at 5.73% while none of second premolars had. Multiple root canals were found in the first premolars at 19.48% and the second premolars at 3.85%. C-shaped canals (C1/C2) were found in the first premolars at 3.72% and the second premolars at 0.48%. All parameters in the first premolars were significantly higher than in the second premolars (p < 0.01). The majority of multiple root canals were defined as Vertucci's type V (1–2 canals). Multiple root canals were frequently separated at the middle level of roots about 6.5–7.0 mm from the cementoenamel junction. Prevalence of multiple roots/root canals and C-shaped canals in mandibular first premolars were significantly higher than in mandibular second premolars. Level of separation in multiple root canals was frequently at the mid-root level. [ABSTRACT FROM AUTHOR]

Introduction: Mandibular premolars have shown higher percentage of root canal failures. The aim of this study was to explore numerous variations in canal morphology seen in mandibular premolars for localization and negotiation of canals as well as their subsequent management in the studied population. Materials and Method: 400 human mandibular premolars in North Indian population were taken and analyzed to record the canal configuration using Spiral CT and Clearing techniques. Statistical Analysis: The comparison of different types by Vertucciwas done using Wilcoxon and Mann Whitney test and found to be significant with Spiral CT. Results: Spiral CT is better in visualizing root canal anatomy as it had shown the presence of Type VI, Type VII and C-shaped canals. Conclusion: A good understanding of external and internal root anatomy helps to reduce the number of missed roots and root canals during treatment, thus increasing the rate of favorable outcomes following root canal treatment. [ABSTRACT FROM AUTHOR]

Objective: To measure the fracture resistance of mandibular premolar roots following root canal instrumentation with different sizes. Methods: A total of100 human permanent mandibular premolars with a straight single canal were decoronated and assigned to 10 groups (n = 10) by block randomisation. In the control group, the roots were uninstrumented, whereas roots in the nine experimental groups were instrumented to different master apical files (MAF) and tapers (MAF/taper): 40/0.05, 45/0.05, 50/0.05, 55/0.05, 60/0.05, 40/0.10, 40/0.15, 45/0.10 and 45/0.15. All roots were subjected to vertical loading until fracture. Results: Fracture load values for instrumented roots were lower than the intact roots of the control group. In 50/0.05, 55/0.05, 60/0.05, 40/0.15 and 45/0.15 groups, the fracture load values were significantly lower than the fracture load value for the control group (P < 0.05) with a 30% decrease. No significant differences in the fracture modes were detected among the 10 groups (P > 0.05). Conclusion: Mechanical instrumentation adversely affects the fracture resistance of roots. When the roots of mandibular premolars were instrumented to a MAF equal to or larger than 50 with a taper of 0.05 or to a MAF of 40 or 45 with a taper of 0.15, the fracture load values significantly decreased. [ABSTRACT FROM AUTHOR]

Knowledge of the normal root canal morphology and its variation is essential to ensure a successful root canal therapy. The aim of this report is to describe the endodontic treatment of two mandibular premolars with aberrant root canal morphology with the aid of dental operating microscope. A 29-year-old Saudi male with three mandibular left premolars was referred by the Prosthodontic Department for endodontic evaluation prior to placement of final coronal restorations. The first premolar was diagnosed as having necrotic pulp while the third premolar was previously treated. Root canal treatment and nonsurgical root canal retreatment were performed for the first and third premolars, respectively. The first premolar had a C-shaped configuration and Vertucci′s Type V (1-2) canal system while the third premolar had Type III configuration (1-2-1). One year later, the teeth were asymptomatic with normal periapical tissues radiographically. Root canal aberrations may occur in any tooth type, and the clinicians should always assume the presence of these aberrations and use all the available tools to detect and manage them.

Abstract Objective To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population. Methods CBCT images of 707 patients, number of roots and canal configuration were identified and categorized according to Vertucci classification. Bilateral symmetry and association between gender and number of roots, as well as gender and root canal configuration were investigated. Results Majority of the patients had one root and type I root canal configuration in mandibular first (96.4%) and second premolar (95.6%). All types of canal configurations were observed except Type VII for the mandibular first premolar, and Types VI and VII for the mandibular second premolar. High degree of bilateral symmetry was seen in both mandibular first and second premolars in terms of the number of roots and canal configuration; 93.8% and 97.8%, respectively. There was an association between gender and number of roots (P = 0.04) and gender and root canal configuration in mandibular first premolar (P = 0.030). Conclusions Single-root with type I canal configuration was the most prevalent of mandibular premolars in the Saudi population. However, incidence of more than one root with different canal configurations was detected. [ABSTRACT FROM AUTHOR]

Introduction: Aberrant root canal morphology of mandibular premolars has always been associated with high endodontic treatment failures. This study was conducted to assess the canal morphology of the mandibular premolars in the Malaysian population using periapical radiographs and cross-sections of the premolar teeth. Materials and Methods: One hundred extracted permanent mandibular premolars with intact apex were randomly collected from various clinics across Malaysia. Radiographs were taken both in mesiodistal (MD) and buccolingual (BL) views to examine the presence of a second canal and to evaluate the type of canal configuration. The roots were then stained and perpendicularly resected to the long axis at three levels (cervical, middle, and apical one third). Digital photographs were taken for each of the cross-section sample and analyzed according to the number and shape of canals. Results: It was found that 78% of the mandibular premolars had single canal in BL radiographic view and 65% in MD view. Seventy-one percent of the single-canal premolars were observed in all three cross-sectional views (1-1-1 configuration). Furthermore, 37% showed oval-shaped canals and 34% showed irregular-shaped canals mainly found at cervical one third; 20% of the teeth showed the canals to be rounded in shape, most prevalent at the apical one third. Two canals with isthmus were observed in 5% of the all cross-sectional views. Conclusion: The majority of mandibular premolars in Malaysian population have a single canal, and there are a few possibilities of two or more canals in these teeth. [ABSTRACT FROM AUTHOR]

Dens invaginatus (DI) is a developmental anomaly that results from an infolding of the dental papilla during tooth development and simulates the appearance of a tooth within another tooth. It shows a wide spectrum of variations in morphology and usually affects the maxillary lateral incisors. This study presents an unusual case of an Oehlers′ Type I DI involving the bilateral mandibular first and second premolars, which presented as an incidental radiographic finding in the first premolars and was associated with a periapical lesion in the second premolars which was successfully treated using nonsurgical endodontics.

Introduction The aim of this study was to investigate the number of roots and the morphology of the root canals of maxillary and mandibular premolars in a selected German population. Methods Randomly selected full-size cone-beam computed tomographic images were collected from 700 patients (45% men and 55% women, average age = 50.21 years). This resulted in a total of 644 first and 512 second maxillary premolars as well as 1044 first and 871 second mandibular premolars. The total number of roots and root canals, the frequency and correlations between the left and right sides, and the incidence in men and women were recorded and statistically analyzed using the Fisher exact and chi-square tests. Canal configurations were classified according to the Vertucci classification. Results First maxillary premolars mainly had 2 roots (1 root: 36.4%, 2 roots: 62.4%, and 3 roots: 1.2%) with predominantly 2 canals (88.4%). The majority of second maxillary premolars had 1 root (82.6%), but 2 root canals (56.3%) occurred more frequently than 1 canal (43.1%). In the first and second mandibular premolars, 1 root was found predominantly (90.76% and 98.16%, respectively) with 1 canal (77.9% and 96.0%), whereas 2 canals were less common (21.9% and 3.6%). Three roots (0%, <0.11%) and 3 canals (0.2%; 0.4%) were rarely found. Vertucci classifications were heterogeneously distributed. Men showed significantly more roots and root canals compared with women ( P < .05), with the exception of the second mandibular premolars. Conclusions This cone-beam computed tomographic study confirmed previous anatomic and morphologic investigations. When treating premolars, the likelihood of additional root canals should be considered. [ABSTRACT FROM AUTHOR]

Objectives: This article investigates the internal and external morphological variability of mandibular premolars along with clinical and radiographical signs that leads to early identification of these cases. Materials and Methods: The authors identified articles by searching the PubMed, Medline and Scopus databases. Inclusion criteria were case reports of mandibular premolars with aberrant internal and external anatomy, articles that describe the origin of anatomy of mandibular premolars, the traits that may influence their external and internal variability through species revolution and articles of new technologies like cone beam computed tomography that help the diagnosis of difficult cases. Results: In the majority of the cases, mandibular premolars are reported to have one root canal running a single root. On the other hand, anatomic irregularities in this group of teeth, such as the existence of more than one root or more than one root canals or even a more complicated root canal system cannot be considered infrequent as it appears in 10-25% of the cases. Conclusion: Successful endodontic treatment of mandibular premolars is a challenge for the clinician as they often present morphological and anatomical abnormalities.

The most difficult clinical considertions in orthograde root canal treatment are generally related to the anatomy of the teeth. Three-canalled maxillary and mandibular premolars (mini-molars) have been reported in several studies. The purpose of this paper was to review various aspects of three-canalled premolars including incidence, clinical and radiographic diagnosis, racial predisposition, access cavity preparation, instrumentation and obturation. [ABSTRACT FROM AUTHOR]

The radiographic recognition of any disease requires a thorough knowledge of the radiographic appearance of normal structure. Intelligent diagnosis mandates an appreciation of the wide range of variation in the appearance of normal anatomical structures. The mental foramen is usually the anterior limit of the inferior dental canal that is apparent on radiographs. It opens on the facial aspect of the mandible in the region of the premolars. It can pose diagnostic dilemma radiographically because of its anatomical variation which can mimic as a periapical pathosis. Hereby we are reporting a rare case of superimposed mental foramen over the apex of right mandibular second premolar mimicking as periapical pathology.

Background: Conventional radiographic techniques being two dimensional, has its restrictions and is confined to limited diagnostic value. However, the incorporation of Cone Beam Computed Tomography (CBCT) gives a three dimensional insight to the tooth morphology and leads to better evaluation and treatment management. Aim: The aim of this study was to evaluate and assess the root canal morphology of mandibular pre-molars in South Indian Population using CBCT radiographic technique. Materials and Methods: One thousand and eighty six and 814 fully erupted mandibular first and second premolars respectively were scanned using CBCT to evaluate the canal morphology according to Vertucci and Gulabiwala’s classification. Results: The most common configuration in mandibular first and second premolars was Vertucci’s Type I(83.81% and 93.48% respectively) followed by Type V (11.97% and 3.5% respectively). Conclusion: South Indian population presented Type IV ertucci’s canal morphology as the most common in mandibular first and second pre-molars followed by Type V. CBCT scanning poses a greater advantage in assessing the complexity of root canal morphology and planning an appropriate endodontic treatment for the same.

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]

Dens invaginatus (DI) is a developmental anomaly that results from an infolding of the dental papilla during tooth development and simulates the appearance of a tooth within another tooth. It shows a wide spectrum of variations in morphology and usually affects the maxillary lateral incisors. This study presents an unusual case of an Oehlers' Type I DI involving the bilateral mandibular first and second premolars, which presented as an incidental radiographic finding in the first premolars and was associated with a periapical lesion in the second premolars which was successfully treated using nonsurgical endodontics. [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]

Complete cleaning and shaping is the key to successful endodontic treatment. A thorough understanding of the internal anatomy and morphology of the root canal system is an important consideration when performing cleaning and shaping procedures. Mandibular premolars are one of the most difficult teeth to treat endodontically because of aberrant root canal anatomy. This article describes case series of mandibular premolars with variations in root canal anatomy treated successfully by conventional endodontic treatment. [ABSTRACT FROM AUTHOR]