Shape variation in modern human upper premolars.

Morphological variation in modern human dentition is still an open field of study. The understanding of dental shape and metrics is relevant for the advancement of human biology and evolution and is thus of interest in the fields of dental anthropology, as well as human anatomy and medicine. Of concern is also the variation of the inner aspects of the crown which can be investigated using the tools and methods of virtual anthropology. In this study, we explored inter- and intra-population morphometric variation of modern humans' upper third and fourth premolars (P3s and P4s, respectively) considering both the inner and outer aspects of the crown, and discrete traits. We worked by means of geometric morphometrics on 3D image data from a geographically balanced sample of human populations from five continents, to analyse the shape of the dentinal crown, and the crown outline in 78 P3s and 76 P4s from 85 individuals. For the study of dental traits, we referred to the Arizona State University Dental Anthropology System integrated with more recent classification systems. The 3D shape variation of upper premolar crowns varied between short and mesio-distally broad, and tall and mesio-distally narrow. The observed shape variation was independent from the geographical origin of the populations, and resulted in extensive overlap. We noted a high pairwise correlation (r1 = 0.83) between upper P3s and P4s. We did not find any significant geographic differences in the analysed non-metric traits. Our outcomes thus suggest that geographical provenance does not play a determinant role in the shaping of the dental crown, whose genesis is under strict genetic control.

Evaluating the Internal Anatomy of Maxillary Premolars in an Adult Saudi Subpopulation Using 2 Classifications: A CBCT-Based Retrospective Study.

BACKGROUND Understanding the root canal morphology is important for successful endodontic treatment. This retrospective cone-beam computed tomography (CBCT) study aimed to compare the adult maxillary premolars (MP), root, and canal morphology among a Saudi Arabian subpopulation based on Vertucci and Ahmed classifications. MATERIAL AND METHODS Scans of 1336 MP - 656 first premolars (MFP) and 680 second premolars (MSP) - were analyzed for the number of roots, morphology of the canals, and symmetry among them. The data were grouped based on the traditional preestablished Vertucci system and newer instantaneous code-based Ahmed classification. Comparative analysis was done using the chi-square test. RESULTS Two roots were common in MFP with 84.4% of the population, followed by those with 1 root and those with 3 roots. In MSP, single roots were more common. The results were non-significant with P values of 0.859 and 0.471, respectively. Most of these MFP had Type IV Vertucci configuration/²TNB¹P¹ Ahmed et al code (TN-tooth number, B-buccal canal, P-palatal canal). In MSP, Type I Vertucci/¹TN¹ Ahmed et al code was most common. However, the results were not statistically significant for the PM with P values of 0.997 and 0.732, respectively. Sex-based difference among them for the roots and root canals was also non-significant. Symmetry among PM in opposite quadrants was 87.1% in MFP and 90% in MSP. CONCLUSIONS Two roots with Type IV (²TNB¹P¹) and 1 root with Type I (¹TN¹) were most common in MFP and MSP, respectively. Symmetry among opposing PM was high.

Micro computed tomography (Micro-CT) characterization of root and root canal morphology of mandibular first premolars: a systematic review and meta-analysis.

INTRODUCTION: Mandibular first premolars are familiar with their varied root canal morphology, causing difficulties and challenges for successful endodontic procedures. This systematic review and meta-analysis aim to study the characterization of root and canal morphology of the first mandibular premolar using micro-computed tomography. METHODOLOGY: The literature search was conducted using electronic web databases like PubMed, Scopus, ScienceDirect and Cochrane with the chosen MeSH key words and data was retrieved until May 2023. Further to perform the statistical analysis, R v 4.3.1 software with "meta", 'metafor" "metaviz" " ggplot2" package was used, and results were represented by odds ratios (OR) and the percentage of forest plots along a 95 per cent confidence interval (CI). RESULTS: The total number of studies meeting the inclusion criteria was 13; these studies were conducted on mandibular first premolar using Micro-CT; the total sample size was 1817. To scan the sample, an X-ray micro-focus CT system (Siemens Inveon CT, Erlangen, Germany) was used in four studies and seven different machines were used in the respective studies. Mimics 10.01 software (Materialize, Leuven, Belgium) and NRecon v.1.6.9 software (Bruker, Kontich, Belgium) were commonly operated. The minimum and maximum voxel size ranges between 11.94 and 50 µm. Vertucci's classification was frequently used (9), while one study applied Ahmed et al. and Vertucci's classification. CONCLUSION: This systematic review provides essential information about the root and canal configurations, radicular grooves, accessory canals, and apical foramina through Micro-CT, aiming to improve the accuracy of endodontic treatment and help practitioners.

Morphological differences between the first and second maxillary premolar crowns: A three-dimensional surface homologous modeling analysis.

OBJECTIVES: The current study used a three-dimensional (3D) surface homologous modeling to analyze the structure of maxillary first premolar (P1) and second premolar (P2) crowns, to identify any morphological differences between them, particularly in their cuspal structures. METHODS: The study sample comprised 27 male elementary and junior high school students from Chiba Prefecture, Japan. Plaster casts were collected and the 3D coordinates were used to measure the crown structures. Thereafter, principal component (PC) analysis was carried out using the 3D coordinates of the homologous models, containing 4498 anatomical data points, including 9 landmarks. RESULTS: The findings indicated that P1 was significantly larger than P2, despite both teeth exhibiting similar intercuspal distances. The homologous model analysis revealed that 61.5 % of the total variance could be explained up to the fourth PC. Overall size and shape in the mesiodistal and buccolingual directions were estimated using PC1 and PC2, respectively. Both components highlighted a shape factor, indicating that the buccal cusp was more well-developed than the lingual cusp in P1 compared to P2. CONCLUSIONS: The variations in the size of the mesial and distal premolar teeth and the relationships between the cusps in the completed tooth crowns can be explained using molecular biology developmental models.

Sexual dimorphism in the three-dimensional detailed crown structure of maxillary first premolars.

OBJECTIVES: Maxillary first premolars have a unique shape because of their curvature features, positional relationship of the cusps, and most prominent points, making them different from other teeth. This study aimed to quantitatively analyze the detailed three-dimensional morphometric structure of maxillary first premolars and sexual dimorphism. METHODS: The study participants were 60 elementary and junior high school students (30 boys and 30 girls) in Japan. The distance between landmarks was measured using the three-dimensional coordinates of plaster casts, and the data collected was statistically analyzed. RESULTS: Sexual dimorphism was greater in the lingual cusp, showing greater variation in size than the buccal cusp. Boys exhibited significantly larger relative distances in the mesiodistal and buccolingual directions than girls; particularly, regarding mesiodistal diameter of the central groove, mesial slope of the buccal cusp, and distal slope of the lingual cusp. These results may be due to a slight difference in the timing of secondary enamel knots between boys and girls during the developmental stage, which was reflected in the sexual dimorphism of the completed teeth. Curvature features, cusp positions, and most prominent points were considered individual traits because they were not interrelated. CONCLUSIONS: Subtle differences during the developmental stage may lead to sexual dimorphism of the completed crown. Furthermore, the morphological characteristics of the maxillary first premolars may be related to their location in the dental arch.

Worldwide Assessment of the Root and Root Canal Characteristics of Maxillary Premolars - A Multi-center Cone-beam Computed Tomography Cross-sectional Study With Meta-analysis.

INTRODUCTION: This worldwide study examined the root and root canal characteristics of maxillary premolars and explored how demographic factors impact the outcomes. METHODS: Observers from 44 countries assessed 26,400 maxillary premolars using cone-beam computed tomography and employed a standardized screening method to gather data on multiple canal morphology and 3-rooted configuration (primary outcomes), as well as secondary outcomes related to root and root canal anatomies. Demographic factors such as ethnicity, sex, and age were collected for each participant. The intra- and inter-observer tests ensured observer reliability. Primary outcomes were represented as odds ratios and untransformed proportions accompanied by 95% confidence interval (CI) forest plots. Meta-analysis compared sub-groups and identified sources of heterogeneity (α = 5%). RESULTS: The overall prevalence of multiple canal morphology in the first premolar was 93.5% (95% CI, 93.3%-94.7%), while in the second premolar, it was 49.7% (95% CI, 44.9%-54.6%). The proportion of 3-rooted configuration was 1.8% (95% CI, 1.4%-2.1%) in the first premolar and 0.4% (95% CI, 0.3%-0.5%) in the second. Asian countries generally displayed fewer roots and root canals, while European nations showed higher counts (P < .05). Males exhibited higher percentages and odds ratios for both outcomes in both premolars. Younger patients demonstrated lower percentages of multiple root canal morphologies (P < .05). Factors such as tooth side, voxel size and field-of-view did not influence the outcomes (P > .05). CONCLUSIONS: The worldwide assessment of root and root canal characteristics of maxillary premolars has revealed a discernible influence of various factors such as tooth type, geographical region, ethnicity, sex, and age.

Multipopulation evaluation of the internal morphology of mandibular first premolars from different South American countries. A micro-computed tomography study.

OBJECTIVE: To evaluate and compare several anatomical parameters of mandibular first premolars from individuals from different Latin American countries using micro-computed tomography. DESIGN: Five hundred extracted mandibular first premolars from Brazilian, Argentinian, Chilean, Colombian, and Ecuadorian individuals were scanned using micro-computed tomography (n = 100 teeth/country). Root canal configurations were classified according to established parameters. Analyses also included: canal volume and surface area, structure model index, distances from the apical foramen to the root apex or the cementoenamel junction, major/minor apical canal diameters, canal orifice shape, and prevalence of ramifications. RESULTS: A single root was the most common anatomy in all countries (range, 97%-100%). Vertucci's type-I canal was the most frequent configuration (range, 36%-66%), followed by C-shaped and type-V canals. The oval-shaped canal orifice was the most predominant in all countries (range, 34%-58%), followed by the circular shape (range, 16%-47%). C-shaped canals occurred in all subpopulations (range, 14%-26%), always associated with radicular grooves. Ranges for canal ramifications were as follows: accessory canals, 36%-73%; lateral canals, 4%-12%; and apical delta, 4%-14% of the teeth. Many anatomic parameters differed significantly between countries (P < .05). CONCLUSIONS: Vertucci's types-I and -V, and C-shaped canals were the most prevalent configurations in the subpopulations investigated. Accessory canals and several complex anatomies were found, with some significantly different frequencies between countries.

CBCT and Micro-CT analysis of the mandibular first premolars with C-shaped canal system in a Chinese population author.

OBJECTIVES: The purpose of this study was to survey the prevalence of C-shaped root canal system in mandibular first premolar in Chinese population by reading Cone-beam computed tomography (CBCT) images and to analyze its anatomical characteristics by CBCT and Micro-computed tomography (Micro-CT). METHODS AND MATERIALS: The prevalence and the morphologic features of C-shaped root canal system were evaluated by observing CBCT images of 760 patients (1520 mandibular first premolars). 66 mandibular first premolars with C-shaped root canal system were scanned by Micro-CT. The morphologic features including radicular groove, C-shaped root canal categories in the cross-sections and in the 3D models, accessory and connecting canals, apical foramina and accessory foramina, were analyzed using image software. RESULTS: C-shaped root canal system was identified in 16.9% of mandibular first premolars. The minimum mesial wall thickness most commonly occurred at the lingual site (69.7%). Regarding to the cross-sectional classification, the maximum was C2 (41.5%). In the 3D classification, the most common was S (34.8%). Accessory canals were observed in 36.4% of the samples and occurred mostly in the middle and apical regions. 42.4% samples had 1-3 variable connecting canals, and 40.9% samples had only one apical foramen. CONCLUSIONS: The incidence of C-shaped root canal system in mandibular first premolars was 16.9% in the Chinese population. The anatomy was very complex and variable, mostly distributed in the middle and apical regions of the root canal. The mesial wall of C-shaped canal was extremely thin on the lingual side.

Influencia de la Morfología Externa de la Raíz de Primeros Premolares Superiores en la Sobreestimación del Espesor Radiográfico Radicular Durante la Preparación para Poste, Evaluados Mediante Tomografía Computarizada Cone Beam / Influence of the External Morphology of the Root of Upper First Premolars on the Overestimation of Radiographic Root Thickness During Post Preparation, Evaluated by Cone Beam Computed Tomography

La investigación tuvo como objetivo determinar la influencia de la morfología externa de la raíz de primeros premolares superiores en la existencia de sobreestimación radiográfica durante la preparación para poste. Con este fin se realizó un estudio transversal in vitro, donde 60 premolares superiores uniradiculares fueron instrumentadas con fresas Gates Glidden y Pesso de calibre 1, 2 y 3. Seguidamente se obtuvieron imágenes radiográficas digitales de cada pieza dentaria mediante un aparato posicionador a una distancia constante en sentido vestíbulo lingual, asimismo se realizaron imágenes tomográficas volumétricas de las muestras. En ambas técnicas imagenológicas se midió el espesor a mesial y distal de las piezas. La sobreestimación fue calculada mediante la diferencia de la medida tomográfica menos la radiográfica. Los resultados indicaron que en ambas paredes radiculares hubo diferencia significativa entre las medidas radiográficas y tomográficas (p<0,05), encontrándose en la pared distal diferencias altamente significativas (p<0,001); además se evidenció que la sobreestimación radiográfica fue mayor en la pared distal. El estudio concluyó que existe sobreestimación radiográfica en premolares superiores durante la preparación para poste de un 20,42 % en promedio, siendo la pared distal la estructura que presenta mayor sobreestimación.

SUMMARY: he investigation´s objective was to determine the influence of external morphology of the root of upper first premolars in the existence of radiographic overestimation during preparation for post. An in vitro cross-sectional study was carried out, where 60 single-rooted upper premolars were instrumented with burs. Gates Glidden and Pesso of caliber 1, 2 and 3, then, digital radiographic images of each dental piece were obtained by means of a positioning device at a constant distance in the buccolingual direction; volumetric tomographic images of the samples were also performed. In both imaging techniques, the mesial and distal thickness of the pieces was measured. The overestimation was calculated by the difference of the tomographic measurement minus the radiographic one. The results indicated that in both root walls there was a significant difference between the radiographic and tomographic measurements (p<0.05), with highly significant differences being found in the distal wall (p<0.001); In addition, it was evidenced that the radiographic overestimation was greater in the distal wall. The study concluded that there is radiographic overestimation in upper premolars during post preparation of 20.42% on average, with the distal wall being the structure that presents the greatest overestimation.

Assessment of the canal anatomy of the premolar teeth in a selected Turkish population: a cone-beam computed tomography study.

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.

Evaluation of root and canal morphology of mandibular premolar amongst Saudi subpopulation using the new system of classification: a CBCT study.

BACKGROUND: The clinician should have complete knowledge of the normal anatomy of the root as well as complexities in the root canal configuration for a better outcome, as missed or improper handling of the canal system can lead to the failure of an entire endodontic procedure. The present study aims to assess the morphology of roots and canals in permanent mandibular premolars in the Saudi subpopulation with a new classification system. METHODS: The present study includes 1230 mandibular premolars (645 first premolars and 585-second premolars) from 500 CBCT images of the patients, including retrospective data. iCAT scanner system (Imaging Sciences International, Hatfield, PA, USA) was used to obtain the images; scanning of 8 × 8 cm images was performed at 120 KVp and 5-7 mA with a voxel size of 0.2 mm. The new method of classification presented by Ahmed et al. 2017 was used to record and classify the root canal morphology, followed by recording the differences regarding the age and gender of the patients. Comparison of canal morphology in lower permanent premolars and its association with gender and age of the patients was done by Chi-square test/ Fisher exact test; the significance level was set at 5% (p ≤ 0.05). RESULTS: The left mandibular 1st and 2nd premolars with one root were 47.31%, with two roots were 2.19%. However, three roots (0.24%) and C-shaped canals (0.24%) were reported only in the left mandibular 2nd premolar. The right mandibular 1st and 2nd premolars with one root were 47.56%, with two roots were 2.03%. The overall percentage of the number of roots and canals in the first and second premolars 1 PM 1 (88.38%), 2 PM 1 B 1 L 1 (3.5%), 2 PM B 1 L 1 (0.65%), 1 PM 1-2-1 (3.08%), 1 PM 1-2 (3.17%), 1 PM 1-2-1-2 (0.24%), 3 PMMB 1 DB 1 L1 (0.48%). However, the C-shaped canals (0.40%) were reported in right and left mandibular second premolars. No statistically significant difference was reported between mandibular premolars and gender. A statistically significant difference was reported between mandibular premolars and the age of the study subjects. CONCLUSION: Type I (1 TN 1) was the major root canal configuration in permanent mandibular premolars, which was higher among males. The CBCT imaging provides thorough details about the root canal morphology of lower premolars. These findings could support diagnosis, decision-making, and root canal treatment, for dental professionals.

Evaluation of interfacial adaptation and penetration of bioceramic-based sealers in oval root canals: A confocal laser scanning microscope study.

To assess the interfacial adaptation and penetration depth of three different bioceramic-based sealers (CeraSeal, EndoSeal MTA, Nishika Canal Sealer BG) compared to an epoxy resin-based sealer (AH Plus) in oval root canals. Fourty extracted single-rooted mandibular premolar with oval canal were prepared and randomly allocated according to the obturation into; CeraSeal, EndoSeal MTA, Nishika Canal Sealer BG and AH Plus. The roots were sectioned at 3, 6 and 9 mm from the apex. The sealer adaptation and the penetration depth were evaluated under confocal laser scanning microscope. One-way ANOVA and Repeated measure ANOVA were used to statistically analyze the data. Nishika Canal Sealer BG showed significantly higher sealer adaptation than EndoSeal MTA (P < .001) at apical and middle thirds. Meanwhile, AH Plus showed significantly higher sealer adaptation than EndoSeal MTA (P = 0.011) at middle third. For sealer penetration, Nishika Canal Sealer BG showed the longest sealer penetration that was significant compared to AH Plus (P < .001) and EndoSeal MTA (P < .001) whereas CeraSeal was significantly higher than EndoSeal MTA (P = 0.029) at coronal third. For AH Plus, there was a significant less sealer penetration at coronal third compared to apical and middle thirds (P < .05). Whereas for EndoSeal MTA, the coronal third has significant less penetration compared to the middle third (P = 0.032). Endoseal has the lowest adaptation and penetration depth. Nishika Canal Sealer BG has better adaptation and penetration depth using single cone obturation technique in oval canal. RESEARCH HIGHLIGHTS: All the tested root canal sealers have some percentage of gaps and vary in their penetration capability into dentinal tubules. Nishika Canal Sealer BG has significantly better sealer adaptation to root dentinal walls than that of EndoSeal MTA at the apical and middle third but not significantly different from other type of sealers used. Nishika Canal Sealer BG has significantly better penetration depth than AH Plus and EndoSeal MTA at the coronal third of radicular dentin.

Evaluation of bone morphology in posterior mandible: A cone-beam computed tomography based study.

Objective: To evaluate the position of the root apices of posterior teeth of mandible with inferior alveolar nerve canal and the cortical bone on cone beam computed tomography. METHODS: The retrospective study was conducted from September to October 2021 at the Aga Khan University Hospital, and comprised cone beam computed tomography scans between November 2017 and October 2021 scans of healthy individuals of either gender aged 18-71 years with healthy, untreated, mandibular posterior teeth bilaterally. Shortest distance from apices of the mandibular posterior teeth to the border of inferior alveolar nerve canal, and to the mandibular buccal cortex were measured on the scans. Data was analysed using SPSS 23. RESULTS: Of the 106 scans, 55(52%) were males and 51(48%) were females. Of the 746 33teeth in the scans, 385(51.6%) were present in the scans of males and 361(48.4%) in those of the females. For all mandibular posterior teeth, the distances in females were shorter than males, but for the distance from root apices to the IAN canal, the difference between genders was significant for the roots of second premolar and second molar only on the left side (p≤0.05). Regarding the distance from the root apices to the buccal cortex, no significant difference was found between the genders, for each type of tooth, (p>0.05). Correlations between the distance from apex to inferior alveolar nerve (r<0.30) and between age and apex to buccal cortex distance (r<0.28) were weak. Conclusion: Procedures planned apical to second premolar and second molar teeth can potentially damage the inferior alveolar nerve.

[Diversity of root canal morphology in mandibular first premolars and its clinical strategies].

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.

Assessment of the Root Canal Similarity in Contralateral Mandibular Incisors.

INTRODUCTION: The purpose of this study was to determine the degree of similarity between contralateral mandibular incisors utilising 3-dimensional (3D) models obtained from micro-computed tomographic (micro-CT) scans of extracted human teeth. The null hypothesis was that contralateral mandibular incisors do not exhibit matching symmetry. METHODS: Sixty pairs (n = 120) of extracted mandibular incisors were obtained from 30 patients and scanned with micro-CT with a voxel size of 15.0 µm. 3D virtual models of the pulpal cavities were rendered. Geometric morphometric deviation analysis was performed after mirroring, automatic alignment, and co-registration of the models of contralateral teeth root mean square (RMS) errors were calculated. The quantitative analysis of the 3D models included 6 different geometric parameters. Data sets were examined with a 2-sample Kolmogorov-Smirnov test. Post hoc retrospective power analysis was performed to find statistical power (α = 0.05). RESULTS: Contralateral pairs had a narrower distribution in deviation than random pairs. Also, contralateral pairs showed a statistically higher similarity coefficient (5 out of 6 geometric parameters) compared to random pairs (P < .001); no difference was found when comparing central to lateral pairs or between Vertucci type I configurations compared to non-type I. RMS errors had significantly lower Contralateral premolars (CPs) values than random pairs (P < .001). CONCLUSIONS: A high degree of similarity was demonstrated for pairing contralateral mandibular incisors using 3D models. The similarity between contralateral central and lateral incisors suggests that when screened and matched, these 4 teeth might be used in endodontic research where similar root canal anatomy is crucial.

Root canal narrowing patterns of mandibular first premolars on panoramic radiographs according to the number of root canals diagnosed on cone beam computed tomographic images.

Understanding the variations in root canal morphology is important for successful endodontic treatment. Mandibular first premolars have a single root in 98% of cases, and multiple root canals are found in approximately 20% of cases. However, the details of these characteristic findings in panoramic radiography and their diagnostic accuracy are unknown. This study aimed to investigate the characteristic radiographic findings of mandibular first premolars possessing multiple root canals and determine the diagnostic accuracy using panoramic radiography. Four radiologists evaluated 347 mandibular first premolars in 186 patients who underwent panoramic radiography and dental cone beam computed tomography (CBCT). Two radiologists confirmed the existence of single or multiple root canals using CBCT. The remaining two radiologists evaluated the imaging findings of the root canal morphology and classified them into two patterns: gradual narrowing and sudden narrowing. In the case of the sudden narrowing pattern, the location of sudden narrowing was also evaluated. A gradual narrowing pattern was observed in 56% of teeth with a single root canal, and a sudden narrowing pattern was observed in 83% of teeth with multiple root canals. When sudden narrowing between the cervical and apical 1/4 of the root canal was used as the diagnostic criterion for multiple root canal teeth, the highest diagnostic performance was observed (sensitivity, 76.1%; specificity, 73.9%). The sudden narrowing between the cervical level and the apical 1/4 level of the root canal is a practical diagnostic criterion for mandibular first premolar with multiple root canals.

Prediction of mesio-distal dimensions of the unerupted permanent canines and premolars using measurements of different groups of erupted teeth: retrospective cross-sectional analysis of digital records in Western Australians.

PURPOSE: Recently, other combinations of teeth are claimed to be better predictors for size estimation of permanent canine and premolars. The present study aimed to determine which combinations of teeth presented an appropriate predictor in Western Australians using digital technology. METHODS: A total of 500 (323 females, 177 males) participants meeting the inclusion criteria were randomly selected from private orthodontic clinics. Mesiodistal dimensions of selected teeth obtained from pre-orthodontic treatment digital records were analyzed using SPSS 20. Fifteen possible combinations of teeth were used to determine the best prediction capability. RESULTS: Different combinations of teeth showed a higher correlation with the sum of permanent canine and premolars. In females, group 13 (Mandibular incisors and maxillary first molars) and in males, group 15 (mandibular incisors, maxillary central incisors, and first molars) and group 14 (mandibular incisors and first molars) showed a higher correlation in maxilla and mandible respectively. Linear regression equations were developed based on the best predictor for each arch and gender. CONCLUSION: Permanent mandibular incisors may not be better predictors when used alone. Newly developed equations, based on different combinations of teeth, more accurately predicted the sum of mesiodistal dimensions of permanent canine and premolars in the Western Australian population.

Diversity of root canal morphology in mandibular first premolars and its clinical strategies / 中华口腔医学杂志

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.

Estudio de la morfología de los conductos radiculares de los primeros premolares superiores en tomografía computarizada de haz cónico / Study of the morphology of root canals of the first upper premolars in cone beam computed tomography

Objetivo: analizar, mediante tomografía computarizada de haz cónico (TC o CBCT [Cone Beam Computed Tomograph]) la frecuencia del tipo de morfología interna de los conductos radi- culares según la clasificación de Vertucci y el número de raíces de los primeros premolares superiores. Material y métodos: en una población argentina de 50 pacientes, 30 de sexo femenino y 20 masculino, que concurrieron a la Cátedra de Diagnóstico por Imá- genes de la Facultad de Odontología de la Universidad de Buenos Aires, se evaluaron 100 primeros premolares superiores con CBCT. Se estudiaron las variables: número de raíces, tipo de morfología interna, edad, sexo y lado. Fueron seleccionadas las tomografías de maxilar superior que incluyeron ambos primeros premolares en salud dental, periodontal y con ápice cerrado. Se realizó una adquisición volumétrica 100 × 90 mm y tamaño de vóxel de 150 µm. Se realizó la exploración de las imágenes en el plano axial de los tercios apical, medio y cervical de las piezas 1.4 y 2.4. Se utilizó un corte axial, observando en él, el tercio apical, medio y cervical de las piezas 1.4 y 2.4. Cada premolar fue analizado con 30 cortes transversales. Se utilizó la clasificación de Vertucci para agrupar las distintas variables anatómicas de los conductos radiculares de los primeros premolares superiores, la cual consta de VIII tipolo- gías. Resultados: el tipo más representativo entre los 100 primeros premolares superiores, dentro de la clasificación de Vertucci, fue el tipo IV (dos conductos separados desde la cámara al ápice). La coincidencia de tipos entre los lados derecho (78%; IC 95%: 65 a 87%) e izquierdo (70%; IC 95%: 56 a 81%) fue significativa. La distribución según el número de raíces en el lado derecho (χ 2 = 2.88) e izquierdo (χ2 = 0.72) no presentó una heterogeneidad significativa. La coincidencia del número de raíces entre los lados derecho e izquierdo fue significativa. Conclusión: se comprobó el tipo de morfología interna más frecuente, el número de raíces y su variabilidad de acuerdo al lado, sexo, y edad; lo cual es de una relevante importancia para realizar una correcta instrumentación y obturación del sistema de conductos radiculares (AU)

Objective: to analyze, using cone beam computed tomography (CBCT), the frequency of the type of internal morphology of the root canals according to the Vertucci classification and the number of roots of the first upper premolars. Material and methods: 100 first upper premolars were evaluated with CBCT, which corresponded to 30 female and 20 male patients in the Chair of Diagnostic Imaging of the Faculty of Dentistry, University of Buenos Aires. Variables were studied: number of roots, type of internal morphology, age, sex and side. The tomography of the upper jaw with both first premolars in dental, periodontal and closed apex health, a 100 × 90 mm volumetric acquisition and a voxel size of 150 µm were selected. An axial cut was used, observing the apical, middle and cervical third of pieces 1.4 and 2.4. Each premolar was analyzed with 30 paraxial cuts. The Vertucci classification was used to group the different anatomical variables of the root canals of the first upper premolars which consists of VIII typologies. Results: the most representative type among the top 100 upper premolars within the Vertucci classification was type IV (two separate ducts from the chamber to the apex). The type coincidence between the right (78%; 95% CI: 65 to 87%) and left (70%; 95% CI: 56 to 81%) los primeros premolares superiores, la cual consta de VIII tipolo gías. Resultados: el tipo más representativo entre los 100 primeros premolares superiores, dentro de la clasificación de Vertucci, fue el tipo IV (dos conductos separados desde la cámara al ápice). La coincidencia de tipos entre los lados derecho (78%; IC 95%: 65 a 87%) e izquierdo (70%; IC 95%: 56 a 81%) fue significativa. La distribución según el número de raíces en el lado derecho (χ 2 = 2.88) e izquierdo (χ2 = 0.72) no presentó una heterogeneidad significativa. La coincidencia del número de raíces entre los lados derecho e izquierdo fue significativa. Conclusión: se comprobó el tipo de morfología interna más frecuente, el número de raíces y su variabilidad de acuerdo al lado, sexo, y edad; lo cual es de una relevante importancia para realizar una correcta instrumentación y obturación del sistema de conductos radiculares (AU))

Root Canal Configuration Of Maxillary First Premolar Teeth In A Subpopulation Of Peshawar Using Tooth Cross-Sectioning Method; An Invitro Study.

Background: Knowledge of tooth morphology is obligatory for achieving success in dental treatment. The root canal configuration of maxillary first premolar (MFP) has been shown to be highly varying. The study was conducted to assess the canal configurations in the roots of upper first premolars within a sample population of Peshawar with the help of tooth cross-sectioning method. Methods: The extracted 250 maxillary first premolars had undergone access cavity preparation after cleaning and pulp was removed from each individual tooth. The root canals were located in the pulp chamber floor and then India ink was injected in to their orifices. When the canals get stained the roots were cross sectioned at three levels to assess the configurations of root canals using a categorization method devised by Weine. SPSS version 19 was used to analyze the data. A p-value of less than 0.05 was considered statistically significant. . Results: Among 250 maxillary first premolars, the common root canal configuration was Weine's type-IV in 30.4% and type-III in 30.0% teeth. Weine's type-I and type II were observed in 24.8% and 8.8% premolars, respectively. Variable root canal configurations were seen in 6.0% teeth. Apical delta was found in 1 (0.4%) tooth. A highly statistically significant difference was observed when root canal configuration was compared with external root morphology. Conclusion: Weine's type-IV and type-III root canal configurations were frequently observed in maxillary first bicuspids.