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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]

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]

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]

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]

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 (a = 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. [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]

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. [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]

Aim To investigate the root canal anatomy of mandibular premolars in a Jordanian population. Methodology Nine hundred extracted mandibular premolars were examined. After the length of the teeth was measured, the presence of developmental grooves and furcated roots was noted. Following the preparation of access cavities, pulp tissue was removed and the canal systems were stained. The teeth were then rendered clear by demineralization and immersion in methyl salicylate. Cleared teeth were examined and the following features were evaluated: (i) type of root canals; (ii) presence and location of lateral canals; transverse anastomosis; (iii) location of apical foramina; and (iv) frequency of apical deltas. Results The mean lengths of first and second mandibular premolars were 22.6 mm (18–27.5 mm) and 22.2 mm (16–26.5 mm), respectively. Although the majority of the specimens corresponded to Vertucci’s classification scheme, analysis of this large data set revealed four additional root canal morphologies. Variable root canal morphologies were found in the mandibular first premolars; two separate apical foramina were found in 33% of the teeth with two canals, compared to 6.2% with one apical foramen. Teeth with three separate apical foramina were scarce (2.2%). The majority of the mandibular second premolars had a single canal; 72% of teeth possessed type I canal systems, whilst 22.8% of the roots had two canals with two separate apical foramina. Conclusions The prevalence of multiple canals in the investigated Jordanian mandibular premolars was high, especially for the second mandibular premolar, in comparison with previous studies performed on populations of different racial origin. [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]

The authors present a method for differentiating between human mandibular premolars: P1 inf and P2 inf. The material with which the method was developed consisted of 260 stone casts. On these, both premolars were present and were intact on at least one side. The study models represented 131 girls and 129 boys, mean age 14.6 yr. In a comprehensive pilot project, a whole range of macromorphologic criteria was tested that, in various combinations, could be expected to be usable for differentiation between P1 inf and P2 inf. On the basis of the pilot study, the total variation was reduced to four criteria-combinations, called types, which, in summary, can be characterized as the following: type 1: flattening of the mesiolingual part of the crown, no lingual lobe; type 2: at least one lingual lobe; type 3: lingual part of the crown symmetrically curved, no lingual lobe; type 4: other characteristics. After definition of the types, their occurrence on P1 inf and P2 inf was definitively registered. Observations were made with a stereomicroscope; 131 premolar pairs from the right side and 129 from the left were registered. Statistical tests showed that there was no significant difference in the distribution of types between variants from the right and left sides, or between girls and boys. These data were therefore pooled for P1 inf and P2 inf, respectively. A subsequent test revealed, as expected, a highly significant difference in the distribution of the four types among 1. and 2. premolar. For estimation of the degree of certainty when the types concerned were used for differentiation, 95% confidence limits were set up from the observed frequencies. Results of these statistical analyses can be described as follows: the probability that a mandibular premolar of type 1 was a 1. premolar was 0.96 (0.93-0.98), that a type 2 variant was a 2. premolar was 0.99 (0.96-1.00), that a type 3 variant was a 2. premolar was 0.79 (0.58-0.93), and that a type 4 variant was a 2. premolar was 0.92 (0.74-0.99). The target groups of this publication are clinical dentists, forensic odontologists, dental anthropologists, and dental morphologists. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the incidence in mandibular premolars of multiple roots and root canals that could be demonstrated radiographically. The images of mandibular premolar teeth as seen on intraoral full-mouth radiographic surveys (547) taken with the paralleling technique were examined. In 99 patients (18.1%) there was at least one premolar tooth with either divided canals or roots. First premolars were involved in 15.7% of patients, and second premolars in 7%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• The prevalence of C-shaped canals in mandibular premolars is low. • Mandibular C-shaped premolars present complex inner morphologies. • Grooves on the mesiolingual surface of the root are associated with C-shaped pattern. To evaluate cone-beam computed tomography images in an Argentine population in order to determine the presence of mandibular premolars with C-shaped canal system and classify them. 697 images were observed, 170 of them fulfilling the selection criteria. Once established the presence of a C-shaped canal system, premolars were classified using Fan's criteria. Data description was made by frequencies and percentages rates, with a 95% confidence interval according to the score method. Comparisons were assessed by means of the Chi-square test with a significance level equal to 5%. Of 269 first premolars, 27 teeth showed C-shaped canal system, i.e. 10%, and of 231 second premolars, 4 presented C-shaped canal system, i.e. 2%. Out of 17 patients presenting first premolars in both sides, 6 showed a bilateral C-shaped canal system pattern and 11 did not present this condition. When the condition was unilateral (n = 15), 7 patients showed C-shaped canal in the tooth 3.4 and 8 patients showed C-shaped canal in the tooth 4.4. The second premolars showed C-shaped canals unilaterally. Along the canal, configuration variations at the three-thirds have been observed for the first and second mandibular premolars. The C-shaped canal system pattern prevalence in mandibular first and second premolars was estimated for the first time in an Argentine population, in vivo. The present report contributes to the epidemiological understanding of the anatomical variable of the inner dental configuration and its extrapolation to the clinical practice. [ABSTRACT FROM AUTHOR]

• Age of 14 years is set to determine the minimum age for criminal responsibility. • Maturity index (IPM) of mandibular first and second premolars was studied. • Cut-off values of IPM 1 < 0.01 and IPM 2 < 0.02 for both teeth were determined. • The combined predictor IPM 1 + IPM 2 < 0.02 shows the highest specificity and better probability. • Mineralization of first and second premolars could be useful in predicting age over 14 years. 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 (

• Mandibular first premolars with RGs had a high incidence of complex canals. • C-shaped canals were mostly observed in first premolars with a Type V configuration. • RGs started on middle thirds, extended to apical and showed mostly deep depressions. • Most of the C-shaped canals exhibited semilunar-type configuration. To conduct an in vivo evaluation of prevalence of root canal configurations, lengths of C-shaped canals, prevalence and depths of radicular grooves (RGs), in mandibular first and second premolars in a Turkish subpopulation using cone beam computed tomography (CBCT). CBCT images of 327 first and 264 second premolars were included. Canal configurations, locations, lengths, and types of C-shaped canals, and RGs were evaluated on CBCT images. Data were statistically analyzed (P < 0.05). First and second premolars were classified as follows: type I, (83.8%, 97.72%); type V, (12.22%, 0.76%); type III, (3.06%, 0.76%); and other types. RGs were exhibited by 14.68% of first and 2.27% of second premolars (P < 0.05). Incidence of complex canals (types III, V and other types, 89.8%) in first premolars with RGs was significantly higher versus without RGs (P < 0.05). C-shaped configuration was exhibited by 4.58% of first (80% semilunar-type), and 1.13% of second premolars (P < 0.05). All first premolars with C-shaped canals showed RGs and complex canals. Complex canals and RGs frequently co-exist in mandibular premolars. C-shaped canals are not common in mandibular premolars, and mostly located in middle thirds. Type V is the most prevalent complex canal configuration in first premolars, and frequently associated with a C-shaped semilunar-type anatomy. [ABSTRACT FROM AUTHOR]