Three-dimensional Localization of Impacted Canines and Root Resorption Assessment Using Cone Beam Computed Tomography

Summary： The purpose of this study was to develop a new way to localize the impacted canines from three dimensions and to investigate the root resorption of the adjacent teeth by using cone beam computed tomography （CBCT）. Forty-six patients undergoing orthodontic treatments and having impacted canines in Tongii Hospital were examined. The images of CBCT scans were obtained from KaVo 3D exam vision. Angular and linear measurements of the cusp tip and root apex according to the three planes （mid-sagittal, occlusal and frontal） have been taken using the cephalometric tool of the InVivo Dental Anatomage Version 5.1.10. The measurements of the angular and linear coordinates of the maxillary and mandibular canines were obtained. Using this technique the operators could envision the location of the impacted canine according to the three clinical planes. Adjacent teeth root resorption.of 28.26 % was in the upper lateral incisors while 17.39% in upper central incisors, but no lower root resorption was found in our samples. Accurate and reliable localization of the impacted canines could be obtained from the novel analysis system, which offers a better surgical and orthodontic treatment for the patients with impacted canines.

Scattering correction method for panel detector based cone beam computed tomography system

A scattering correction method for a panel detector based cone beam computed tomography system is presented. First, the x-ray spectrum of the system is acquired by using the Monte Carlo simulation method. Secondly, scattered photon distribution is calculated and stored as correction matrixes by using the Monte Carlo simulation method according to scanned objects and computed tomography system specialties. Thirdly, scattered photons are removed from projection data by correction matrixes. A comparison of reconstruction image between before and after scattering correction demonstrates that the scattering correction method is effective for the panel detector based cone beam computed tomography system.

Cone beam computed tomography aided diagnosis and treatment of endodontic cases:Critical analysis

Although intraoral radiographs still remain the imaging method of choice for the evaluation of endodontic patients, in recent years, the utilization of cone beam computed tomography(CBCT) in endodontics showed a significant jump. This case series presentation shows the importance of CBCT aided diagnosis and treatment of complex endodontic cases such as; root resorption, missed extra canal, fusion, oblique root fracture, nondiagnosed periapical pathology and horizontal root fracture. CBCT may be a useful diagnostic method in several endodontic cases where intraoral radiography and clinical examination alone are unable to provide sufficient information.

Establishment of reference mandibular plane for anterior alveolar morphology evaluation using cone beam computed tomography

To propose a method of establishing the reference mandibular plane (MP), which could be reestablished according to the coordinates of the reference points, and then facilitate the assessment of anterior alveolar morphology using cone beam computed tomography (CBCT), sixty patients with bimaxillary protrusion were randomly selected and CBCT scans were taken. The CBCT scans were transferred to Materialism's interactive medical image control system 10.01 (MIMICS 10.01), and three dimensional models of the entire jaws were constructed. Reference points determining the reference MP were positioned in the coronal, axial, sagittal windows, and the points were exactly located by recording their coordinates in the interfaces of software. The reference MP provided high intra-observer reliability(Pearson's r 0.992 to 0.999), and inter-observer reliability (intra-class correlation coefficients (ICCs) 0.996 to 0.999).

Evaluation of Frontal Sinus Index in Establishing Sex Dimorphism Using Three-Dimensional Cone Beam Computed Tomography in Northern Saudi Arabian Population

Purpose:Identification of sex of unknown people becomes important in situations of mass disaster.Previous studies have shown that morphological characteristic of frontal sinus is distinctive to particular individual and hence,literature suggests that it can be used in establishing identification of a person.However,few researches have concluded that,its use in detennining sexual dimorphism is limited.Aim:This study aimed to evaluate frontal sinus index using cone beam computed tomography(CBCT)and differentiate sex dimorphism based on the index obtained.Materials and Methods:A retrospective cross-sectional study was undertaken using three-dimensional-CBCT scans.By simple random sampling method,150 scans were selected,out of which 74 were of male and 76 were of female within the age group of20-64 years.The frontal sinus width and the height were measured,and the ratio was taken as frontal sinus index.This index was correlated to the differentiation of sex.Data were analyzed using SPSS,and sex dimorphism was assessed using discriminant function analysis.Results:The mean height of the frontal sinus in both males and females was 30.12±7.6 mm and 30.14±7.8 mm,respectively.The mean width of frontal sinus in males(13.39±3.6 mm)was slightly more than that of females(12.06±3 mm).Conclusion:The parameter frontal sinus index measured using CBCT was found to be a contributing factor in sex determination in forensic identification within the sample population.

Cone beam computed tomographic analyses of alveolar bone anatomy at the maxillary anterior region in Chinese adults

To provide an anatomical basis for clinical implant esthetics,we evaluated the morphology of the nasopalatine canal（NPC） and analyzed labial and interproximal bone anatomy at the maxillary anterior region.We sought to investigate the effect of maxillary protrusion and tooth labiolingual inclination on labial bone anatomy in Chinese adults.Three dimensional（3D） images were reconstructed using cone-beam computed tomography（CBCT） images from 80 Chinese subjects and by SimPlant 11.04.The dimensions of the NPC,the thickness and profile of the labial bone,the width and height of the interproximal bone,angle sella-nasion-subspinale（SNA） and angle upper central incisor-nasion,subspinale（U1-NA） were measured.The incisive foramen of the NPC was markedly wider than its nasal foramen.The dimension of its labial bone wall demonstrated an increasing width from the crestal to apical measurements.The labial bone at the maxillary anterior region was rather thin,especially at 3 mm below the cemento-enamel junction（CEJ） and the mid-root level;the profile of the labial bone was more curved at the central incisor,and the interproximal bone became wider and shorter posteriorly.There were significant relationships between maxillary protrusion and labial bone profile,tooth labiolingual inclination and labial bone thickness（P 〈 0.02）.To achieve optimal esthetic outcome of implant,bone augmentation is necessary at the maxillary anterior region.For immediate or early placement at the maxillary anterior region,the implant should be located palatally to reduce labial bone resorption and marginal recession;its apex should be angulated palatally to avoid labial perforation at the apical region.To protect the NPC,implants at the central incisor region should be placed away from NPC.

Cone beam computed tomographic evaluation of pharyngeal airway in North Indian children with different skeletal patterns

BACKGROUND In growing patients with skeletal discrepancies,early assessment of functional factors can be vital for the restoration of normal craniofacial growth.AIM To compare airway volumes in patients with mandibular retrognathism with the normal anteroposterior skeletal relationship,thereby assessing the association between cephalometric variables and airway morphology.METHODS Cone-beam computed tomography volume scans,and lateral cephalograms,3-dimensional airway volume and cross-sectional areas of 120 healthy children(54 boys and 66 girls mean age 15.19±1.28)which were done for orthodontic assessment were evaluated.The subjects were divided into 2 groups based on the angle formed between point A,Nasion and point B(ANB)values and cephalometric variables(such as anterior and posterior facial height,gonial angle etc.)airway volumes,and cross-sectional measurements were compared using independent t tests.Pearson’s correlation coefficient test was used to detect any relationship of different parts of the airway and between airway volume and 2-dimensional cephalometric variables.RESULTS Means and standard deviations for cephalometric,cross-sectional,and volumetric variables were compared.ANB,mandibular body length and facial convexity were statistically highly significant(P<0.01)whereas condylion to point A,nasal airway and total airway volume(P<0.05)were statistically significant.The nasal airway volume and the superior pharyngeal airway volume had a positive correlation(P<0.01),nasal airway was correlated to middle(P<0.05)and total airway superior had a relation with middle(P<0.05),inferior and total airway(P<0.05),middle was related to all other airways;inferior was also related to all the airways except nasal.Lateral cephalometric values were positively correlated with the airway volume with Frankfurt Mandibular Plane Angle and facial convexity showed significant correlations with total airway volume(P<0.05).Additionally,ANB angle was significantly correlated with total airway volume and superior airway(P<0.05).CONCLUSION The mean total airway volume in patients with retrognathic mandible was significantly smaller than that of patients with a normal mandible.

Morphometric and Volumetric Evaluation of Maxillary Sinus as an Aid in Sex Identification in Forensic Odontology-A Cone-Beam Computed Tomography Study

Background:Various methods are used in forensic odontology for the purpose of sex and personal identification.Some of them include cheiloscopy,rugoscopy,mandibular measurements,and study of paranasal sinuses.In our study,we have used maxillary sinus as an aid in sex identification.For this purpose,we have evaluated the morphometric and volumetric measurements of the maxillary sinus using a 3-Dimensional imaging modality,Cone Beam Computed Tomography.Aims and Objectives:Sex and age identification are important in the process of identification of both the living and the dead.Hence,this transverse retrospective study was done to appraise the precision of the dimensions and volume of the maxillary sinus to aid in sex and age identification.Material and Methods:Eighty full Field of View(FOV)Cone-Beam Computed Tomography(CBCT)images were retrieved from the archives which were matched with age and sex.The maxillary sinuses on either side were measured mediolaterally in the axial section and supero-inferiorly in the coronal section.The volumetric analysis of the sinus was done in the sagittal section.The sex was classified using discriminant function analysis and the differences were compared using independent t-test.The differences with age were analyzed using one-way ANOVA.Results:Independent t-test was done for comparison of the sinuses between both sexes.Maxillary sinuses measurements were larger among the males both superior-inferiorly on either side(P<0.001)and mediolaterally on the right(P<0.049)showed statistically significant values.A significant correlation existed while comparing the maxillary sinus volume among both the sexes on either side(P<0.001 and<0.002 in the case of right and left respectively).On comparing the supero-inferior and mediolateral measurements and the maxillary sinus volume on either side among the various age groups,the values were statistically insignificant.Present study shows that the maxillary sinus measurements using Cone-beam computed tomography were diagnostic in the identification of sex but not in age estimation and can be used in forensic dentistry.

Scatter correction for cone-beam computed tomography using self-adaptive scatter kernel superposition

The authors propose a combined scatter reduction and correction method to improve image quality in cone beam computed tomography （CBCT）. The scatter kernel superposition （SKS） method has been used occasionally in previous studies. However, this method differs in that a scatter detecting blocker （SDB） was used between the X-ray source and the tested object to model the self-adaptive scatter kernel. This study first evaluates the scatter kernel parameters using the SDB, and then isolates the scatter distribution based on the SKS. The quality of image can be improved by removing the scatter distribution. The results show that the method can effectively reduce the scatter artifacts, and increase the image quality. Our approach increases the image contrast and reduces the magnitude of cupping. The accuracy of the SKS technique can be significantly improved in our method by using a self-adaptive scatter kernel. This method is computationally efficient, easy to implement, and provides scatter correction using a single scan acquisition.

New clinical application of digital intraoral scanning technology in occlusal reconstruction:A case report

BACKGROUND Digital intraoral scanning,although developing rapidly,is rarely used in occlusal reconstruction.To compensate for the technical drawbacks of current occlusal reconstruction techniques,such as time consumption and high technical requirements,digital intraoral scanning can be used in clinics.This report aims to provide a way of selecting the most suitable maxillo-mandibular relationship(MMR)during recovery.CASE SUMMARY A 68-year-old man with severely worn posterior teeth underwent occlusal reconstruction with fixed prosthesis using digital intraoral scanning.A series of digital models in different stages of treatment were obtained,subsequently compared,and selected using digital intraoral scanning together with traditional measurements,such as cone beam computed tomography,joint imaging,and clinical examination.Using digital intraoral scanning,the MMR in different stages of treatment was accurately recorded,which provided feasibility for deciding the best occlusal reconstruction treatment,made the treatment process easier,and improved patient satisfaction.CONCLUSION This case report highlights the clarity,recordability,repeatability,and selectivity of digital intraoral scanning to replicate and transfer the MMR during occlusal reconstruction,expanding new perspectives for its design,fabrication,and postoperative evaluation.

Successful individualized endodontic treatment of severely curved root canals in a mandibular second molar:A case report

BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A 26-year-old Chinese female patient presented with intermittent and occlusal pain in the left mandibular second molar.The patient had undergone filling restoration for caries before endodontic consultation.With the aid of cone beam computed tomography(CBCT),a large periapical radiolucency was observed,and curved root canals in a mandibular second molar were confirmed,depicting a severe and curved distolingual root.Nonsurgical treatments,including novel individualized preparation skills and techniques and the use of bioceramic materials as an apical barrier,were performed,and complete healing of the periapical lesion and a satisfactory effect were achieved.CONCLUSION A case of severely curved root canals in a mandibular second molar was successfully treated and are reported herein.The complex anatomy of the tooth and the postoperative effect were also evaluated via the three-dimensional reconstruction of CBCT images,which accurately identified the aberrant canal morphology.New devices and biomaterial applications combined with novel synthesis techniques can increase the success rate of intractable endodontic treatment.

Nomogram to predict the risk of endoscopic removal failure with forceps/baskets for treating submandibular stones

BACKGROUND Endoscopic removal with forceps/baskets is favored in treating submandibular stones due to its minimal invasiveness.However,recent studies have found that endoscopic removal failure(ERF)is not unusual,and stones in such cases still need to be removed with other surgical methods.If the risk of ERF can be predicted preoperatively,it could be helpful for surgeons when choosing the appropriate therapy.AIM To develop a predictive nomogram for the risk of ERF when treating submandibular stones based on their preoperative clinical features.METHODS A total of 180 patients with 211 submandibular stones treated from January 2012 to December 2020 were included in the current study.Based on the preoperative clinical features of the stones,independent risk factors for ERF were identified by logistic regression analysis.The stones were then randomly divided into training and testing sets.A nomogram was constructed to predict the risk of ERF using the training set and then validated using both sets.The predictive performance of the nomogram was assessed by calibration curves and the concordance index(Cindex).RESULTS Three independent predictors,location(P=0.040),transverse diameter(P<0.001)and longitudinal diameter(P<0.001)measured on the cone beam computed tomography(CBCT)images of the submandibular stones,were identified and included in the predictive nomogram.Calibration curves of the nomogram showed good agreement between the predicted and observed probabilities in both sets.The C-index in the training set was 0.917(95%CI,0.875-0.959)and that in the testing set was 0.925(95%CI,0.862-0.989).CONCLUSION A nomogram based on the location,transverse and longitudinal diameters on CBCT images of submandibular stones showed satisfactory efficacy in predicting the risk of ERF preoperatively when treating submandibular stones.

Endodontic management of the maxillary first molar with special root canals:A case report and review of the literature

BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of endodontic treatment and prognosis.This article presents an endodontically managed left maxillary first molar with an unusual palatal root morphology.The available literature on the anatomic variation of maxillary first molars is also reviewed.CASE SUMMARY A 36-year-old man with no medical history presented to the Stomatology Department of Peking University Third Hospital complaining of a toothache during mastication in the maxillary left posterior region for approximately 3 mo.He had a spontaneous and intermittent toothache that had worsened,particularly at night.The diagnosis based on clinical examination,X-ray imaging,and cone beam computed tomography(CBCT)was symptomatic irreversible pulpitis.Nonsurgical endodontic therapy was performed for the left maxillary first molar.Five root canals revealed by CBCT included a special palatal root canal(1-2-1-shaped),two mesiobuccal root canals,and one distobuccal root canal.Evaluation of the CBCT images confirmed the root canal morphology and the clinician performed more effective cleaning,obturation,and therapy.Finally,the tooth was restored using composite resin,and the patient was satisfied with the result.CONCLUSION CBCT and a complete review of the literature may be beneficial for investigating the root canal system to achieve a biological and functional therapeutic effect.

The Comparison of Entrance Surface Radiation Dose to the Thyroid Gland Region in Different Dental Panoramic Radiography

Introduction:The proven radio sensitivity and the position of the thyroid gland make it a significant organ during the dental radiography exposure.Objectives:This study compared the surface radiation dose to the thyroid gland region during two different techniques of two dimensional(2D)conventional orthopantomography(OPG)and three dimensional(3D)OPG reconstructed from cone beam computed tomography(CBCT).Methods:The entrance surface dose to the thyroid region of the patients was evaluated using a personal dosimeter in a sample of 156 patients who prescribed for an OPG examination.Results:The obtained mean dose values for conventional OPG and reconstructed OPG from CBCT are 7.47μSv and 28.65μSv,respectively.Further a significant difference(p<0.05)was observed between those two doses.Conclusions:A significant amount of dose reduction to the thyroid gland region can be obtained when using conventional OPG compared to the CBCT.

Exploring the practice of common oral diseases among the patients visiting in the selected dental college and hospital in Bangladesh

Background:Having the ability to identify potential health risk factors such as lifestyle,ethnicity,health status,and social determinants associated with oral health status risk,health care providers can take an active role in health screening to discover any need for clinical preventive services,including dental preventive services,and can detect health problems.Methods:A descriptive type of cross-sectional study was conducted to explore the practice of common oral diseases among the patients visiting in the selected dental college and hospital in Bangladesh from October 2019 to December 2019.About 100 patients were interviewed through a semi-structured questionnaire,followed by an oral examination through a checklist and a face-to-face interview.A systematically random sampling technique was employed to select the study population.Results:Among them,the(21-30)year age group shows a maximum 20%,whereas the(71-80)year age group represents the minority with only 2%.Among them,56%were male and 44%were female.Students represent the majority of 26%,whereas others(day laborers)represent only 4%.Decayed teeth remained in 72%of cases,teeth were missing in 31%of cases,and filled teeth were present in 24%of cases.A majority of 71%clean teeth once daily,whereas only 29%clean teeth twice daily.Again,only 30%brush teeth at night and a maximum of 95%brush teeth in the morning.Moreover,a maximum of 68%use toothpaste and brushes,while only 4%use meswak for cleaning their teeth.About 4%of cases with no debris,51%of cases with less than 1/3rd of the tooth with debris,32%of cases with 1/3rd-2/3rd of the tooth with debris,and 13%of cases with more than 2/3rd of the tooth with debris were present.Again,about 30%had no calculus,52%less than 1/3rd of tooth,16%in between 1/3rd and 2/3rd of tooth,and 2%more than 2/3rd of the calculus was present.About 47%of mild,22%of moderate,6%of severe and 25%had no inflammation.Furthermore,for treatment purposes,20.69%was advised for scaling,19.66%for filling,16.90%for root canal treatment,17.59%for extraction,17.24%for prosthodontic treatment,1.03%for orthodontic treatment,2.07%for pulpotomy,2.41%for pulpectomy,and 2.41%for minor surgery.Overall,about 72%of the respondents,mostly the students,are suffering from decayed teeth,which may be due to a lack of frequency of brushing,indicating 95%that it is once daily.In addition,the most alarming situation among them is about 20.69%required scaling,which may be due to improper and inadequate brushing maintenance.Conclusion:to some extent,the above scenario may reflect the negative hallmark for our country’s younger generation in terms of oral health practice.Therefore,the establishment of a preventive oral health policy by our policymakers for the general population,mostly school-going students,on an emergency basis.

Clinical and radiographic features of Hutchinson-Gilford progeria syndrome: A case report

Hutchinson-Gilford progeria syndrome(HGPS) is a rare dysmorphic syndrome characterized by several features of premature aging with clinical involvement of the skin, bones, and cardiovascular system. HGPS has an estimated incidence of one in four million to one in eight million births. The main clinical features of HGPS include short stature, craniofacial dimorphism, alopecia, bone fragility, and cardiovascular disorders. The most frequent cause of death is myocardial infarction at a mean age of 13 years old. Dental manifestations include delayed development and eruption of teeth, discoloration, crowding and rotation of teeth, and displaced teeth. Cone beam computed tomography images revealed the absence of the sphenoid, frontal, and maxillary sinus, flattening of the condyles and glenoid fossa, and bilateral hypoplasia of the mandibular condyles. The disease is caused by mutations in lamin A/C(LMNA). Here, we present a case report of an 11-year-old boy with classical features of HGPS, which was caused by a de novo germ-line mutation(C1824T, G608G) in exon 11 of the LMNA gene. Some uncommon HGPS-associated features in our patient, such as alterations in the facial sinuses and hypoplasia of the condyles, contributed to the expansion of the phenotypic spectrum of this syndrome from a dentomaxillofacial perspective.

Clinical relevance of distolingual roots and periodontal status in mandibular first molars: a cross-sectional study employing CBCT analysis

Objectives:Distolingual root of the permanent mandibular first molar(PMFM-DLR)has been frequently reported,which may complicate the treatment of periodontitis.This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background.Materials and methods:A total of 836 cone beam computed tomography(CBCT)images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China.Among them,complete periodontal charts were available for 69 Chinese patients with 103 teeth.Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR,bone loss,and periodontal clinical parameters,including clinical attachment loss(CAL),probing pocket depth(PPD),gingival recession(GR),and furcation involvement(FI).Results:The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4%and 26.3%,respectively.Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section,while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section.Conclusions:The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort.The morphological features of DLR were correlated with the periodontal status of mandibular first molars.This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.

Accuracy Assessment of a Novel Radiographic Method to Evaluate Guided Bone Regeneration Outcomes Using a 3D-Printed Model

The aim of this study was to evaluate the accuracy and reproducibility of a morphological contour interpolation(MCI)based segmentation method for the volumetric measurement of bone grafts around implants.Three 3D-printed models(one with a cylinder and two with a geometrically-complex form)were fabricated to simulate implant placement with a simultaneous guided bone regeneration(GBR)procedure.All models were scanned using a cone beam computed tomography(CBCT)instrument with the same parameters.The true volumes of the bone grafts in the models were assessed using computer-aided calculation(controls).For the test measurements,both manual and MCI-based methods were used.A comparison between the measured and true volumes was performed to evaluate the accuracy.The coefficients of variation of repeated measurements were calculated to evaluate the reproducibility.In addition,the execution time was recorded and a comparison between the two methods was performed.The high accuracy of the MCI-based method was found with differences between the measured value and actual volume,which never exceeded 7.3%.Excellent reproducibility was shown,with coefficients of variation never exceeding 1.1%.A shorter execution time was observed for the MCI-based method than for the manual method.Within the confines of this study,the MCI-based method may be suitable for volumetric measurements of grafted bone around implants.