Root Of First Molar Research Articles

Evaluation of Bone Mineral Changes in Panoramic Radiographs of Hypothyroid and Hyperthyroid Patients Using Fractal Dimension Analysis

Objective Hyperthyroidism and hypothyroidism are endocrinopathies that cause a decrease in bone mineral density. The aim of this study is to investigate possible bone changes in the mandible caused by hyperthyroidism and hypothyroidism using fractal analysis (FA) on panoramic radiographs.Material and Methods Panoramic radiographs of a total of 180 patients, including 120 patient groups (60 hyperthyroid, 60 hypothyroid) and 60 healthy control groups, were used. Five regions of interests (ROI) were determined from panoramic radiographs and FA was performed. ROI1: geometric midpoint of mandibular notch and mandibular foramen, ROI2: geometric midpoint of mandibular angle, ROI3: anterior of mental foramen, ROI4: basal cortical area from distal mental foramen to distal root of first molar, ROI5: geometric center of mandibular foramen and mandibular ramus.Results While a significant difference was observed between the patient and control groups regarding ROI1 and ROI2 (p < 0.05); there was no significant difference between the groups in relation to ROI3, ROI4, and ROI5. All FA values were lower in the hyperthyroid group than in the hypothyroid group.Conclusion Fractal analysis proves to be an effective method for early detection of bone mass changes. In the present study, it was concluded that while the mandibular cortical bone was intact, trabecular rich regions were affected by osteoporosis caused by thyroid hormones. Necessary precautions should be taken against the risk of osteoporosis in patients with thyroid hormone disorders.

Frequency of Multiple Canals in Mandibular Premolars and its Correlation with Other Anatomical Variants (C Shaped Canals in Mandibular Second Molars): A Retrospective and Cross-sectional Study

Introduction: Recognition of variations in molar root morphology is critically important for dental procedures such as root canal treatment and apical surgery. Usage of CBCT enables systemic evaluation of teeth including the number of roots and canals, location of roots, etc. The aim of this study was to determine the frequency of multiple canals in mandibular first and second premolars and to evaluate correlations between other anatomical variants using Cone beam computed tomography (CBCT).&#x0D; Methodology: The protocol of this retrospective, cross-sectional study was approved by the Ethics Committee of Saveetha Dental Hospital, Chennai, India. Images of mandibular premolars were obtained from patients who had undergone CBCT scanning at the hospital between January 2018 and November 2020.Cross-sectional images in the axial, coronal, and sagittal planes were reconstructed using GALILEOS ComfortPLUS ( Sirona 3D)is an advanced CBCT that provides seamless workflow integration. Serial axial, coronal and sagittal-plane CBCT images were closely examined at 1.0-mm intervals from the canal orifice to the apex.&#x0D; Results: Using SPSS software (ver. 21; SPSS, Inc., Chicago, IL, USA), chi-squared test was performed for analyses of different parameters involved. Various anatomical variants such as distolingual roots of first molars, C shaped canals of second molars are highly correlated with different canal configurations of mandibular premolars.&#x0D; Conclusion: This retrospective study showed that different configurations of mandibular premolars canals was significantly correlated with the presence of Distolingual root (DLRs) in first molars, and C shaped canals in second molars. Understanding and identifying anatomical variants is important in comprehensive success of endodontic treatment.

Smart distalization of the upper arch with an easy, efficient and no-compliance procedure.

In conventional Class II treatment, distalisation of the maxillary arch usually requires multiple phases of tooth movement during which anchorage loss can occur. In order to solve this issue, a rational and simple technique has been developed. Instead of using intraoral distalisers along with palatal mini-implants, Ni-Ti superelastic loops are used to obtain molar distalisation while buccal interradicular miniscrews (BIM), preferably placed between the roots of upper premolars, supply the necessary anchorage. Once the distalisation of molars and second premolars is performed, miniscrews are placed between the roots of first molars and second premolars after removing the previous miniscrews. Elastic chains or tie-backs, which go from the new miniscrews to the hooks of a 0.019×0.025-inch stainless-steel archwire, produce the retraction of incisors, canines and first premolars with optimal control of anchorage. Clinical cases are shown to illustrate the technique.

Evaluation of the Bone Thickness of Mandibular Molars using Cone Beam Computed Tomography

Objective: To investigate buccal and lingual bone thicknesses and fenestration rate of mandibular first and second molars using cone-beam computed tomography (CBCT). Methods: A total of CBCT images of 41 patients were selected and overall 120 mandibular molars were investigated. The buccal and lingual alveolar bone widths were measured at apex of the roots. The prevalence of fenestration in mandibular molars was recorded. Statistical analyses were performed. Results: The buccal bone widths of mesial root of second molars were significantly lower than the lingual (p&lt;0.05). The lingual bone widths of mesial and distal root of second molars were lower than the buccal (p&lt;0.05). The lowest thickness of buccal and lingual bone was observed in mesial root of first molar and distal root of second molar. The prevalence of fenestration in mandibular first and second molars was 5% and 10%. Conclusion: The buccal bone widths were lower at the first molar than the second molar. All fenestrations in first molar were in buccal aspect, in second molar were in lingual aspect. Topographical proximity of the buccal side of first molar and the lingual side of second molar to bone plate create a risky region for endodontic treatment or spread of infection.

Comparative evaluation of displacement and stress distribution pattern during maxillary arch distalization with Infra Zygomatic Screw- A three dimensional finite element study

This study aimed to evaluate and compare the distribution of stress and displacement of teeth during maxillary arch distalization with IZC (Infra zygomatic crest) screw with two maxillary positions and different lever arm heights. Six three-dimensional finite element models of the maxillary arch were constructed with third molars extracted. Models 1, 2 and 3: IZC 6 (mesial to mesiobuccal root of first molar, 6) with 0mm, 4mm and 8mm lever arm height; Models 4, 5 and 6: IZC 7 (mesial to mesiobuccal root of second molar, 7) with 0mm, 4mm and 8mm, respectively. MBT preadjusted Brackets (slot size 0.022×0.028") were placed over the clinical crown's centre with 0.019×0.025" stainless steel archwire on all six models. Retraction force of 4N was applied with different combinations of IZC screws and lever arm bilaterally using Nickel-Titanium (NiTi) closed coil spring. Then, evaluation of stress distribution, von Mises stress and maxillary teeth displacement were performed using ANSYS 12.1 software. In this study, maximum von Mises stress in alveolar bone (cortical bone) was observed in Model 4 (107.79MPa) at the screw fixation site that was within the optimum limit (135MPa). Different extents of displacements like labiolingual tipping of crown, labiolingual tipping of root, extrusion and intrusion were noticed. The models with 0mm and 4mm lever arm height (models1, 2, 4 and 5) showed more controlled crown and root movements in comparison to 8mm long lever arm models (models 3 and 6). In model 5, a maximum distal movement compared to all other five models was observed. IZC 7 position showed the most favourable results (maximum distalization) with the lever arm height of 4mm. Therefore, the nearer the force to the centre of resistance of the tooth, the greater is distalization. Stresses on the IZC screw decreases when lever arm height increases, in all the models.

Anatomical Analysis of Mandibular Posterior Teeth using CBCT: An Endo-Surgical Perspective.

Objective:This study sought to analyse the relationship between mandibular posterior teeth and the surrounding anatomical structures.Methods:A total of 170 CBCT images were examined to obtain measurements regarding the following: buccolingual (BL) and mesiodistal (MD) root thickness at the standard level of resection (3 mm from the apex), the thickness of the overlying buccal and lingual bone at the same level, the proximity of the mandibular canal (MC) to the apices of the mandibular posterior teeth, as well as the horizontal location of the mental foramen (MF).Results:The BL root width at 3 mm from the apex was the broadest at the mesial roots of the first molars with males: 5.33±0.99 mm and females: 5.16±0.88 mm (mean±SD). The root width was narrowest at the second premolars (males: 3.80±0.83 mm; females: 3.61±0.60 mm). At the same level; the buccal bone was thickest over the distal roots of the second molars (males: 6.92±1.85 mm; females: 6.95±1.95 mm) and thinnest over the first premolars (males: 1.73±0.93 mm; females: 1.49±1.01 mm), while the lingual bone was thickest over the distal roots of the first molars (males: 5.58±1.36 mm; females: 4.52±1.24 mm) and thinnest over the distal roots of the second molars (males: 3.13±1.50 mm; females: 2.60±1.46 mm). The nearest root apices to the MC were the distal roots of the second molars (male: 1.21±1.45 mm; female: 1.75±1.97 mm), while the furthest were the mesial roots of the first molars (male: 4.00±2.39 mm; female: 4.77±2.58 mm). The most common horizontal location of the MF was between the first and second premolars (51.8%). The lingual bone was significantly thinner over both roots of first molars in females (P<0.05).Conclusion:As the position of the teeth became more posterior, the buccal bone thickness increased, the lingual bone thickness decreased, and the distance to the MC became closer. CBCT analysis provides distortion- and superimposition-free images of the relevant anatomic structures.

Anatomical analysis of mandibular posterior teeth for endodontic microsurgery: a cone-beam computed tomographic evaluation.

The purpose of this study was to analyze the anatomical structures relevant for endodontic microsurgery in the mandibular posterior teeth using a cone-beam computed tomography (CBCT). A total of 963 mandibular posterior teeth were analyzed in CBCT scans from 133 patients. The buccolingual and mesiodistal dimensions of the root and the buccal bone thickness overlying the root were measured at the site of root resection (apical 3 mm). At this location, the relationship between the buccal cortical bone and root was classified into three types (separated, contact, and exposed), and the distance from the root apex to the mandibular canal was measured. The thickest buccolingual dimension of the roots was found in the mesial roots of first molars, at 5.59 ± 0.97 mm. The buccal bone thickness overlying the root became thicker in posterior tooth locations. In the first premolar and first molar mesial root, contact was the most common type of relationship between the buccal cortical bone and root. As the position of the teeth became more posterior, the distance from the apex to the mandibular canal became shorter. As the position of the teeth became more posterior, the buccal bone thickness increased and the distance to the mandibular canal became closer; therefore, particular attention is required for posterior teeth. The first premolar and the first molar mesial root are often in contact with the buccal cortical bone, which may allow infections to spread to the buccal structure more easily and negatively affect for post-surgical healing. When planning and performing endodontic microsurgery, understanding the anatomical structure of the surgical site will help minimize tissue damage and reduce complications.

Topographic Analysis of the Isthmus in Mesiobuccal and Mesial Roots of First Molars in a South Korean Population

The purpose of this study was to evaluate the incidence and microscopic anatomy of the isthmus to provide more precise anatomical information about the mesiobuccal (MB) roots of the maxillary first molars and the mesial (M) roots of the mandibular first molars. Twenty-eight maxillary and 31 mandibular first molars were embedded, sectioned, stained, and observed at 30× magnification to evaluate the incidence and microscopic anatomy of the isthmus. The incidence of an isthmus 3 mm from the apex was 89.3% and 100% in the MB roots of the maxillary first molars and in the M roots of the mandibular first molars, respectively. The mean dentin thickness between the isthmus and the distal root surface was <1 mm at a distance of 3 mm from the apex in both types of roots. In this study, whenever two main canals were located in the MB roots of the maxillary first molars and in the M roots of the mandibular first molars, the likelihood of the presence of an isthmus increased. Therefore, clinicians should be aware of the thinnest dimensions in the distal surface of the MB roots of the maxillary first molars and the M roots of the mandibular first molars during nonsurgical and surgical root canal treatment.

Proximity of the roots of maxillary posterior teeth to the floor of maxillary sinus and cortical plate: A cone-beam computed tomography assessment.

The purpose of the study is to assess the vertical and horizontal relationship between the roots of maxillary posterior teeth and neighboring structures like the floor of the maxillary sinus and cortical plates using cone-beam computed tomography (CBCT). 100 CBCT scans of the patients from the Indian population were analyzed. Vertical and horizontal relationship between the roots of maxillary posterior teeth and the floor of the maxillary sinus was divided into 4 types and 3 types, respectively. Distances between the root apices and the floor of the maxillary sinus and cortical plate was measured for each root and results were formulated. In total 365 teeth were assessed, 185 first molar and 180 second molar. It was found that the roots of first molar and second molar usually had type 2 (root apices in close contact with the floor of maxillary sinus) and type 3 (roots projecting laterally into the sinus, but its apices are outside the sinus border) vertical relationship respectively with the floor of maxillary sinus. The deepest portion of the floor of the maxillary sinus was most commonly seen projecting between buccal and palatal roots. The mean distance between the cortical plate and root was highest for the distobuccal root of second molar i.e., 1.20 mm SD = 0.97. The distobuccal root of the first molar and mesiobuccal root of the second molar are closest to the sinus floor, hence clinician should be extra cautious while working on these roots during endodontic or surgical procedures in the Indian population.

Radiographic assessment of mandibular canal in Nepalese population: a study based on cone beam computed tomography images

Background: Mandibular canal runs in the body and ramus of mandible and provides pas­sage for inferior alveolar nerve. Knowledge on spatial relationship of canal with adjacent structures prevent damage to nerve during surgical procedures. This study aims to find three-dimensional relationship of canal as well as its relation with third molar.&#x0D; Methods: This was a cross sectional and retrospective study conducted on Cone Beam Com­puted Tomography images. The relation and position of canal with third molar and position of canal in vertical and horizontal dimensions were analyzed.&#x0D; Results: Mandibular canal was found to be progressively descended in 43% of the canals. The canal was located apical to third molar in 61.9% cases and regarding contact relation, 121(56%) of the third molars had no contact with the canal. Buccal cortical plate was maxi­mum at the level of distal root of second molar and minimum at the level of mesial root of first molar and was reverse for lingual cortical plate. The highest distance between upper border of canal and inferior border of mandible was at mental foramen 13.55±2.27 mm and lowest at mesial root of second molar, 8.72±2.59 mm. Minimum distance between superior border of canal and alveolar crest was distal to second molar (13.78±3.54 mm) and maximum between first molar and second premolar (17.91±3.08 mm).&#x0D; Conclusions: It was observed that canal was interradicularly placed and was by penetrated by third molar in some cases. Thickness of cortical plates varied in various locations buccally and lingually.

RADIOGRAPHIC ASSESSMENT OF MANDIBULAR CANAL IN NEPALESE POPULATION: A STUDY BASED ON CONE BEAM COMPUTED TOMOGRAPHY IMAGES

Background: Mandibular canal runs in the body and ramus of mandible and provides pas­sage for inferior alveolar nerve. Knowledge on spatial relationship of canal with adjacent structures prevent damage to nerve during surgical procedures. This study aims to find three-dimensional relationship of canal as well as its relation with third molar.&#x0D; Methods: This was a cross sectional and retrospective study conducted on Cone Beam Com­puted Tomography images. The relation and position of canal with third molar and position of canal in vertical and horizontal dimensions were analyzed.&#x0D; Results: Mandibular canal was found to be progressively descended in 43% of the canals. The canal was located apical to third molar in 61.9% cases and regarding contact relation, 121(56%) of the third molars had no contact with the canal. Buccal cortical plate was maxi­mum at the level of distal root of second molar and minimum at the level of mesial root of first molar and was reverse for lingual cortical plate. The highest distance between upper border of canal and inferior border of mandible was at mental foramen 13.55±2.27 mm and lowest at mesial root of second molar, 8.72±2.59 mm. Minimum distance between superior border of canal and alveolar crest was distal to second molar (13.78±3.54 mm) and maximum between first molar and second premolar (17.91±3.08 mm).&#x0D; Conclusions: It was observed that canal was interradicularly placed and was by penetrated by third molar in some cases. Thickness of cortical plates varied in various locations buccally and lingually.

Effects of mechanical force application on the developing root apex in rat maxillary molars

ObjectivesWe aimed to investigate the effects of mechanical force application on the developing root apex in vivo. DesignMechanical force was applied on the maxillary first molars of Sprague–Dawley rats at postnatal day 21 for 1, 3, 5, and 7 days to induce tooth movement. We observed the developing root apex of the mesial root of first molar by using micro-focus X-ray computed tomography, histological staining, immunohistochemistry and in situ hybridization to analyze apical cell proliferation and gene expression. Moreover, the force was released after 3 and 7 days of tooth movement, and root apical morphology at postnatal day 35 was subsequently observed. ResultsAfter 1 and 3 days of tooth movement, root apical morphology was altered by increasing immune-reactivity of laminin in the forming periodontal ligament. After 7 days of tooth movement, the root length decreased significantly with bending root apex, decreased cell proliferation and altered gene expression in developing root apex. At postnatal day 35, apical morphology showed no obvious abnormality when the force was released after 3 days of tooth movement, whereas root apical bending was not rescued when the force was released after 7 days. ConclusionsRelatively short-term force application had no obvious adverse effects on the developing root apex. However, relatively long-term force application altered root apex by affecting Hertwig’s epithelial root sheath morphology and apical cellular behavior.

The relation of maxillary root apices and the maxillary sinus floor among patients with different skeletal patterns in Iraqi samples

Background: Understanding the morphological characteristics between the floor of the maxillary sinus and the tips of the maxillary posterior roots is crucial in orthodontics involving diagnosis and treatment planning. The aim of this study was to evaluate the distances from the maxillary posterior root apices to the inferior wall of the maxillary sinus, thickness and density of maxillary sinus floor using cone-beam computed tomography images and the relationships between roots and maxillary sinus according to gonial angle and skeletal pattern. Materials and methods: Three-dimensional images of each root were checked, and the distances were measured along the true vertical axis from the apex of the root to the sinus floor, and the thickness and density of maxillary sinus floor in 60 patients (30 males, 30 female) aged 18 to 25 years. Evaluation of the differences between groups which classified to gonial angle and skeletal pattern which were done according to the comparsion between the mean statistic tests. Results: results showed that the density of floor of maxillary sinus at the first molar roots region in class III were significantly lower than class I and II, also the distance between the floor of maxillary sinus and both distobuccal and palatal roots of first molar were significantly lower in class I than other classes, while the thickness of maxillary sinus floor at the distobuccal root of first molar were significantly higher in class III than other classes. In gonial angle difference, the maxillary sinus floor density and distance to the maxillary posterior roots had no significant difference in all groups, while the thickness of maxillary sinus floor at distobuccal and palatal of second molar roots region were significantly higher in large gonial angle than small and normal angles. Conclusion: subjects with class I skeletal pattern have small distance between the maxillary sinus floor and the maxillary posterior roots due to the pneumatisation of maxillary sinus causing more difficult and time consuming orthodontic treatment.

Evaluation of maxillary buccal alveolar bone before and after orthodontic alignment without extractions: A cone beam computed tomographic study.

To assess the changes in the maxillary buccal alveolar bone during alignment without extractions. Secondarily, to evaluate the changes in arch dimensions and buccolingual inclinations of teeth and to identify risk factors for bone loss. Twenty-two adolescents with crowded permanent dentitions were treated without extractions with Damon 3MX brackets. Cone beam computed tomographic scans were taken before treatment (T0) and after alignment (T1). Bone thickness (BT) and height from the cementoenamel junction to the alveolar crest (BH) were evaluated at the maxillary central incisors, second premolars, and buccal roots of first molars. Changes in all variables from T0 to T1 were assessed. Correlations between bone changes and initial bone thickness, initial arch widths, initial crowding, amount of expansion, amount of tipping, and amount of molar rotation were calculated. BT decreased and BH increased significantly for the incisors and mesiobuccal root of the first molars. Arch dimensions generally increased together with tipping. Bone loss was correlated with crowding and amount of expansion in the premolar region. Initially thinner BT was correlated with greater apical migration of bone for the incisors. Nonextraction alignment with self-ligating brackets led to arch expansion associated with tipping of teeth. Expansion related to alignment resulted in horizontal and vertical bone loss at the incisors and mesiobuccal root of the first molars. Thinner BTs and more severe crowding before treatment increased the risk for buccal bone loss.

Duration from Initial Symptoms to Diagnosis of Vertical Root Fracture in Dental Offices.

Diagnosing vertical root fracture (VRF) is difficult. Here, we retrospectively investigated the duration from initial symptoms to a definite diagnosis of VRF in dental offices. Data were collected on patients with VRF between July 2013 and June 2015. Initial symptoms were ascertained from clinical records. The focus was on the maxillary second premolars and mesial roots of the mandibular first molars, where VRF is most frequent. All VRF in the bilateral dentition was analyzed. Only cases in which the buccal-lingual plane of the root was fractured were included. Data from 31 dental offices revealed a total of 39 VRFs in the maxillary second premolars and 43 in the mandibular mesial roots of the first molars. The patients comprised 42 males and 40 females, and the average age was 59.7±11.6 years at initial onset of symptoms. The mean duration from initial symptoms to a definite diagnosis in the maxillary second premolars was 18.3±22.5 months, while that in the mandibular first molars was 16.1±17.8 months. The cumulative diagnostic rate was 48.7% at 12 months and 79.5% at 24 months in the maxillary second premolars, and 38.1% at 12 months and 86.0% at 24 months in the mandibular first molars. No significant difference was observed between tooth type. If VRF is suspected, doctors should explain the risks of tooth extraction and begin considering treatment options. The present results revealed that 80% of VRFs were diagnosed within 2 years of initial onset of symptoms.

Ridge Dimensions of the Edentulous Mandible in Posterior Sextants: An Observational Study on Cone Beam Computed Tomography Radiographs.

To evaluate the ridge dimensions of posterior sextant in totally edentulous mandibles. Cone beam computed tomography scans of 136 patients were retrospectively included for analysis. At sites corresponding to the second premolar (site a) and the mesial and distal root of first molar (sites b and c, respectively), bone height (BH) and bone width (BW) were measured. BH significantly decreased from site a (11.20 ± 4.03 mm) to site c (10.28 ± 3.33 mm). Males showed a significantly higher BH compared with females at all sites (P < 0.001), No significant impact of age on BH was found. BW increased from coronal to apical at all sites. At all height levels, BW increased from mesial to distal (BWc > BWb > BWa). BH decreased from mesial to distal, whereas BW showed an increase. Sex showed a significant impact on BH, with males having on average a 2.8 mm greater height than females, but not on BW. Age did not significantly influence the dimensions of the residual bone crest.

Mandibular Canal Location: Cone-beam Computed Tomography Examination

IntroductionThe increased use of implants and potential endodontic misadventures can lead to nerve damage. The purpose of this study was to use cone-beam computed tomography (CBCT) measurements to investigate mandibular canal (MC) location in relation to mandibular posterior teeth, the dimension of the buccal and lingual bone over the MC, the diameter of the MC, and the anterior loop location near the mental foramen. MethodsCBCT scans from 106 patients (age, 18–69 years) were used to evaluate measurements from 636 teeth and respective MC areas. ResultsRespective locations of MC to teeth (buccal, inferior, or lingual) were as follows: second molar (57% buccal, 40% inferior, and 3% lingual), first molar (18% buccal, 55% inferior, and 27% lingual), and second premolar (33% buccal, 55% inferior, and 11% lingual). Buccal bone thickness over the MC was thickest at mesial root of second molars and thinnest over the second premolar (5.4 versus 2.6 mm). The lingual bone next to the MC was thickest over the second premolar and thinnest at distal root of first molars (3.8 versus 1.7 mm). The average diameter of the MC along the length of the canal from second molar to second premolar was 3.03 mm on left and 2.91 mm on right. The anterior loop was present in 10.4% of patients, with the average depth below bone of 13.43 mm. The anterior loop was more often seen on the left side than right and occurred bilaterally 50% of the time. ConclusionsMandibular bone thickness, nerve location, and dimension data all contribute to a useful knowledge base for practitioners. The application of CBCT imaging techniques aids in the surgical treatment, while offering advantages over conventional periapical and panoramic films.

Cone-beam Computed Tomography: Anatomic Analysis of Maxillary Posterior Teeth—Impact on Endodontic Microsurgery

IntroductionIt is imperative that the endodontic surgeon be knowledgeable of the anatomic dimensions of the surgical site. If cone-beam computed tomography is not available because of location/cost, it is prudent for the clinician to consult a knowledge base for the surgical site. An understanding of the root thickness of maxillary premolars and molars at the preferred level for root resection (3.0–3.6 mm), bone thickness over these roots, and the proximity of each root apex to the maxillary sinus will help the surgeon before and during the surgical procedure. MethodsCone-beam computed tomography scans from 155 patients were used to evaluate measurements from 505 teeth and respective areas. Results(1) Buccal bone was thinnest over the buccal root of the 2-rooted first premolar (0.66 mm) and the mesiobuccal (MB) root of the first molar (0.84 mm) and thickest over the MB root of the second molar (1.91 mm). (2) The palatal bone was thinnest over the palatal root of the maxillary first molar (1.24 mm) and thickest over the single-rooted second premolar (3.26 mm). (3) The longest distances to complete resection were found for the 2-rooted first and second premolars (8.81 mm and 9.14 mm, respectively) and the MB root of the second molar (7.40 mm). (4) The MB root of the second molar had the closest proximity to the sinus floor, with an average distance of 0.66 mm. ConclusionsAn understanding of the maxillary posterior tooth anatomy for apical resection is beneficial to the endodontist.

Analysis of the Root and Canal Morphologies in Maxillary First and Second Molars in a Chinese Population Using Cone-beam Computed Tomography

IntroductionWe analyzed and characterized the root and canal morphologies in maxillary first and second molars in a large sample of Chinese patients using reconstructed cone-beam computed tomographic (CBCT) imaging. MethodsMaxillary first (n = 1558) and second (n = 1539) molars were collected from Chinese patients (N = 844) who had undergone in vivo CBCT imaging. The root canal number and morphology were determined according to Vertucci's classification. ResultsA single root was found in 0.06% of first molars, which showed type I canal systems. However, second molars with a single root (4.2%) showed widely varied canal systems. The buccal roots of first molars with 2 separate roots showed type I, II, or III canal systems, whereas those of 2-rooted second molars showed widely varied canal systems. The incidence of fused roots was 1.38% for first molars and 23.9% for second molars, whereas canal fusion within fused roots was observed in 4.5% of first molars and 10.6% of second molars. Additional canals were observed in 67.8% and 29.7% of mesiobuccal roots, 1.8% and 0.7% of distobuccal roots, and 0.7% and 0.3% of palatal roots in 1523 and 1017 first and second molars with 3 separate roots, respectively. The mesiobuccal root canal number showed bilateral symmetry between 79% of first molars and 82.3% of second molars, with a concurrence rate of 59.8% between adjacent molars. ConclusionsWe reported the root and canal morphologic variations in maxillary first and second molars, which have not been reported for Chinese populations. Further studies should focus on canals in fused roots and mesiobuccal roots.

Odontogenic Myxoma of Mandible with Unusual (Sunburst) Appearance: A Rare Case Report

Odontogenic Myxoma of Mandible with Unusual (Sunburst) Appearance: A Rare Case Report