Morphology changes of maxillary molar distalization by clear aligner therapy / Cambios de la morfología en la distalización de molares maxilares mediante terapia con alineadores transparentes

SUMMARY: To evaluate the skeletal, dento-alveolar and soft tissue morphology changes after maxillary molar distalization by clear aligner therapy and identify the significant efficacy of molar distalization,18 patients in conformity with the inclusion criteria were selected. Pre- and post-treatment Cone Beam Computed Tomography (CBCT) were examined to measure the angular and linear parameters. All subjects were completed non-extraction clear aligner treatment by distalizing molars. A paired-t test and independent-samples t-test were performed to observe the difference between before and after treatment and the difference between the first molar and second molar respectively. P-values <0.05 were considered statistically significant. Predicted movement rate was calculated by the formula: (actual movement(mm)/planned movement(mm)) x100%. Most variables of pre- and post-treatment showed no statistical difference(P<0.05), excepting SNA angle (P<0.05) and Upper lip/E-line linear (P<0.01) due to incisor retraction. The first and second molar revealed a translation movement without significant tipping and vertical movement. Clear aligners provided a high predictability (83.44 %) of distalization the maxillary first molar, and 85.14 % of the maxillary second molar. Clear aligners can effectively achieve distal displacement of molars.

RESUMEN: Se seleccionaron 18 pacientes, de acuerdo con los criterios de inclusión, para evaluar los cambios en la morfología esquelética, dentoalveolar y de los tejidos blandos después de la distalización de los molares maxilares, mediante la terapia con alineadores transparentes e así identificar la significativa eficacia de la distalización de los molares. Se examinó a través de tomografía computarizada de haz cónico (CBCT) antes y después del tratamiento para medir los parámetros angulares y lineales. Todos los sujetos completaron el tratamiento con alineadores transparentes sin extracción mediante la distalización de los molares. Se realizó una prueba t pareada y una prueba t de muestras independientes para observar la diferencia entre antes y después del tratamiento y la diferencia entre el primer molar y el segundo molar, respectivamente. Los valores de p<0,05 se consideraron estadísticamente significativos. La tasa de movimiento prevista se calculó mediante la fórmula: (movimiento real (mm)/movimiento planificado (mm)) x 100 %. La mayoría de las variables de pre y postratamiento no mostraron diferencia estadística (P<0,05), excepto el ángulo SNA (P<0,05) y el labio superior/línea E lineal (P<0,01) debido a la retracción del incisivo. El primer y segundo molar revelaron un movimiento de traslación sin inclinación significativa y movimiento vertical. Los alineadores transparentes proporcionaron una alta previsibilidad (83,44 %) de la distalización del primer molar superior y del 85,14 % del segundo molar superior. Los alineadores transparentes pueden lograr efectivamente el desplazamiento distal de los molares.

Protocolo estandarizado para la observación de la imagen tomográfica en endodoncia / Standardized protocol of observation of the tomographic image in endodontics

Objetivo: establecer un protocolo estandarizado de observación de la tomografía computarizada de haz cónico (CBCT) en endodoncia, para determinar de manera sistemática las dimensiones de las lesiones apicales crónicas. Métodos: análisis y aplicación de las herramientas de los software tomográficos de haz cónico usados para la exploración de tejidos dentales y periapicales, con previa revisión bibliográfica del tema. Posteriormente, se diseñaron los pasos sistemáticos estandarizados de observación y medición de la imagen tomográfica dental en endodoncia, con lo cual se estableció el protocolo. Finalmente, se entrenaron dos endodoncistas en la aplicación del protocolo para medir sistemáticamente las dimensiones de lesiones apicales crónicas (altura, profundidad y ancho) Resultados: se generó un documento con material gráfico sobre los pasos a seguir del protocolo estandarizado y se realizó una prueba estadística de concordancia, que evidenció un alto grado de coincidencia entre las mediciones hechas por las endodoncistas entrenadas (observadoras 2 y 3) frente a las de una radióloga experta (observadora 1). El mayor grado de acuerdo se encontró entre las observadoras 1 y 2 en la vista sagital al evaluar la altura de la lesión (ICC: 0.9997545), mientras que, las observadoras 1 y 3 lograron el mayor grado de acuerdo en la vista axial (ICC 0.9996737, IC 95%) al evaluar la profundidad de la lesión. Conclusión: la aplicación de este protocolo sencillo, sistemático y estandarizado de observación de tomografía dental permite evaluar de manera confiable, reproducible y precisa la imagen de la periodontitis apical y, a su vez, alcanzar un alto grado de concordancia cuando se miden lesiones apicales.

Objective: Establish a standardized protocol for the observation of Cone Beam Computed Tomography (CBCT) in endodontics, to systematically determine the dimensions of chronic apical lesions. Methods: Analysis and application of the tools of the specific Cone Beam Computed Tomography software for the exploration of dental and periapical tissues, prior literature review of the subject. Subsequently, the design of standardized systematic steps of observation and measurement of the dental tomographic image in Endodontics, thus establishing the Protocol. Finally, training of 2 Endodontists in the application of the Protocol by an expert Radiologist, measuring the dimensions of chronic apical lesions (height, depth and width) in 45 high-resolution conical beam dental tomographs and checking its usefulness, through a concordance test using the Intraclass Correlation Index (ICC). Results: A written document was generated with explanatory graphic material on the steps to follow by the Standardized Protocol and a statistical concordance test was carried out that evidenced a high degree of agreement between the measurements of the trained endodontists (observers 2 and 3) against the expert radiologist (observer 1). The highest degree of agreement was found among observers 1 and 2 in the sagittal view when assessing the height of the lesion (ICC: 0.9997545), while observers 1 and 3 achieved the highest degree of agreement in axial vision (ICC 0.9996737, 95% CI) when assessing the depth of the lesion. Conclusion: The application of this simple, systematic and standardized protocol for the observation of dental tomography in clinical practice makes it possible to reliably, reproducibly and accurately assess the image of apical periodontitis, prior observer training, allowing a high degree of concordance to be achieved when apical lesions are measured.

Sex determination by osteometric assessment of the mastoid process using Cone Beam Computed Tomography / Determinação do sexo em uma população Iraniana por avaliação osteométrica do processo mastóide em imagens de TCFC

Objective: Sex determination is one of the most important parameters to identify in forensic science. Because the mastoid process is the most resistant to damage due to its position in the skull base, it can be used for sex determination. The purpose of this study was to measure the dimensions and convexity and internal angles of the mastoid process to present a model of sex determination in Iranian population. Material and methods: This study was performed on three-dimensional images of 190 Cone Beam Computed Tomography (CBCT) of 105 women and 85 men. On each CBCT the distance between the porion and the mastoid (PM), mastoid length (ML), the distance between the mastoidale and the mastoid incision (M-I), the mastoid height (MH), the mastoid width (MW), intermastoidale distance (IMD) the lateral surfaces of the left and right mastoids (IMLSD) and the Mastoid medial convergence angle (MMCA) was measured on both the right and the left. The data were analyzed by descriptive statistics, t-test, and discriminant function analysis. Results: Significant differences were found for all variables except MMCA and MF in both sex. All measured variables except MW were greater for men than women. The discriminant model achieved a total accuracy of 93.7%. Among the measured factors IMD and IMSLD had the most influence on sex determination. Conclusion: Measuring the dimensions of the mastoid process is a very good method for sex determination with high accuracy of 90% (AU)

Objetivo: A determinação do sexo é um dos parâmetros mais importantes para identificação na ciência forense. Por ser o processo mastóide resistente a danos, devido a sua posição na base do crânio, este poderia ser usado na determinação do sexo. O objetivo deste estudo foi mensurar as dimensões, convexidade e ângulos internos do processo mastóide para apresentar um modelo de determinação do sexo em uma população Iraniana. Material e métodos: Este estudo foi realizado em 190 imagens de tomografia computadorizada de feixe cônico (TCFC), sendo 105 mulheres e 85 homens. Em cada TCFC foram realizadas medidas no processo mastóide em comprimento (ML), altura (MH), largura (MW) em ambos os lados direito e esquerdo, também foi medida a distância entre o Pórion e o processo mastóide (PM), distância até incisura mastoidea (M-I), distância entre as superfícies mediais (IMD) distância entre as superfícies laterais dos processos direito e esquerdo (IMLSD) e o ângulo de convergência medial (MMCA). Os dados foram analisados por estatística descritiva, teste t e análise de função discriminante. Resultados: Diferenças significativas foram encontradas para todas as variáveis, exceto MMCA e MF em ambos os sexos. Todas as variáveis medidas, exceto MW, foram maiores para os homens do que para as mulheres. O modelo de análise de função discriminante alcançou uma precisão total de 93,7%. Entre os fatores medidos, o IMD e o IMSLD tiveram a maior influência na determinação do sexo. Conclusão: Podemos concluir que as dimensões do processo mastóide constituem um método para determinação do sexo, em população Iraniana, com precisão de 90% (AU)

Role of Cone-Beam Computed Tomography in the Detection of Maxillary Sinus Disease

Dentists must understand the role of maxillary sinus diseases and their relationship to teeth and supportingstructures. The most maxillary sinus disease is Odontogenic maxillary sinusitis. Cone-beam computedtomography (CBCT) is the imaging choice in dental practice to evaluate maxillary sinuses and maxillofacialstructures. Maxillary sinuses carry a variation of mucosal thickening. If the mucosa of maxillary sinuses exceedsmore than 2 mm, it indicates the possibility of infection in the maxillary sinuses. More than 50% of patients visitingthe dental practice have thickening of lining mucosa more than 2 mm. Limitation for CBCT includes difficulty todifferentiate between soft-tissue attenuation. This review aims to emphasize the role of CBCT in the detection ofmaxillary sinus diseases in dental practice. In conclusion, the CBCT examination is the best and convenientimaging tool in the dental practice that can identify the presence of pathology in maxillary sinus before surgeryor post-operative complication and follow-up. This literature review was done to emphasize the demand for CBCTas an imaging investigation tool. This imaging modality is increased nowadays due to its accurate diagnosis ofdental disease and routine evaluation of alveolar bone for implant placement and sinus lift surgery.

Evaluation of Dental CBCT in Assessing the Furcation Involvement in Mandibular Molars

Furcation involvement (FI) refers to the invasion of the bifurcation and trifurcation areas of multi-rooted teeth by periodontal disease. Diagnosis of FI by 2D radiographs can be overcome by the use of cone-beam computed tomography (CBCT) imaging technique. Objective: To compare the measurements of furcation depth by clinical method and CBCT in assessing the FI. Methods: The present study comprised of 60 furcation involved mandibular molars from 45 patients suffering from Chronic Generalized Severe Periodontitis. Teeth having probing pocket depth of ≥6mm were considered for the study. Clinical measurements of furcation depth were made on buccal or lingual sides of mandibular molars by using endodontic file with stopper which was done by two clinicians. The CBCT measurements were performed by measuring the deepest vertical and horizontal furcation defects at each furcation entrance. These measurements were then recorded, compiled and statistically analysed. Results: The comparison of furcation involvement clinically by clinician 1 and CBCT measurements in buccal side was statistically significant (p=0.0255*), while it was statistically not significant (p=0.3696 NS) on lingual side. Similarly, the comparison of furcation involvement clinically by clinician 2 and CBCT measurements in buccal side was statistically significant (p=0.0278*), while it was statistically not significant (p=0.4951 NS) on lingual side. Conclusion: CBCT technique can be considered a reliable tool for detecting FI as CBCT imaging showed high accuracy and moderate reproducibility in the assessment of furcation depth.

Design and Implementation of Automated QA Software for Cone Beam CT Image / 中国医疗器械杂志

In order to improve the speed and accuracy of cone beam CT image quality assurance, an automatic image quality assurance software based on feature extraction is designed and implemented. This paper introduces how the software can realize the positioning of Catphan500 phantoms and the selection of ROI in each module through Canny algorithm and Hough transform circle detection. For the different modules in the Catphan500 phantom, this paper describes the calculation methods of HU accuracy, spatial linearity, HU uniformity and spatial linearity in the software. Finally, the article verifies the feasibility of the software through experiments.

Application of an individualized appliance in orthodontic treatment / 口腔疾病防治

@#More than 20 years have passed since the advent of individualized appliances, which are designed according to the corrective target position. Through a series of digital technology-aided design and production processes, individual appliances have been increasingly recognized and accepted by the public. At present, there are three types of individualized orthodontic appliances: individualized lingual orthodontic appliances, non-bracket invisible appliances and individualized labial appliances. Because of their good effects in orthodontics, these appliances have gradually become mainstream orthodontic treatment tools. However, many doubts persist regarding their use in clinical treatment. This article reviews the development history, design principles and characteristics of the three types of individualized appliances. The results of a literature review showed that CAD/CAM and CBCT provide a hardware foundation for personalized orthodontic appliances that simplifies the therapeutic process. Additionally, individualized appliances also place higher demands on orthodontists. This article could provide references for and help with the clinical selection and use of individualized appliances.

Effective Debridement And Subsequent Obturation Of Tooth With Morphoanatomic Variations In Non Syndromic Patients– A Series Of 3 Case Reports

Taurodontism is a morphoanatomical anomaly of teeth characterised by enlarged pulp chamber with apically displaced pulp chamber floor and furcation.Endodontic treatment of a taurodont is challenging and requires special handling because of proximity and apical displacement of roots. In performing root canal treatment on such teeth, one should appreciate the complexity of the root canal system, canal obliteration and configuration, and the potential for additional root canal systems. Careful exploration of the grooves between all orifices particularly with magnification, use of ultrasonic irrigation; and a modified filling technique are of particular use. This paper presents three case reports on diagnosis and successful endodontic management of hypertaurodontic teeth, in non-syndromic patients

Three-dimensional study on symmetry of the first molar and its peripheric alveolar bone in skeletal class III patients with mandibular deviation / 上海交通大学学报（医学版）

Objective: To compare the difference of the first molar and alveolar morphology between the deviated side and non-deviated side in skeletal class III patients with mandibular deviation by using cone-beam computed tomography (CBCT) image combined with three-dimensional reconstruction measurement technology. Methods: Fifty-six asymmetric CBCT data were evaluated by Mimics 10.0 and 3-Matic software. Some measures were analyzed by t-test including the buccolingual angle, the mesiodistal angle, crown root ratio of first molar and the thickness of alveolar or cancellous bone. Results: The buccolingual angle and crown root ratio of mandibular first molar were significantly larger on the deviated side than on the non-deviated side (P=0.021, P=0.004). Compared with the non-deviated side, the buccal and total cancellous bone thickness of mandibular first molar were significantly smaller on the deviated side (P=0.043, P=0.048). There was no significant difference in the ratio of buccal and total cancellous bone thickness on mandibular first molar (both P=0.118). The measurements of maxillary first molar and maxillary alveolar bone morphology were not significantly different between two sides (all P>0.05). Conclusion: In skeletal class III patients with mandibular deviation, although the buccolingual compensation of first molar is found, the position of first molar in the alveolar bone is symmetrical. The asymmetry of alveolar bone morphology are mainly manifested in the reduction of the buccal and total cancellous bone thickness on the mandibular deviated side.

Comparison of alveolar bone changes in maxillary anterior area secondary to different kinds of retraction method of anterior teeth: a cone-beam computed tomography study / 上海交通大学学报（医学版）

Objective • Using cone-beam computed tomography (CBCT) to compare alveolar bone changes in maxillary anterior area secondary to maxillary incisor retraction adjunct with tip (R&Tp) and retraction adjunct with torque (R&Tq) movements. Methods • Forty teenagers with Angle's class Ⅱ division 1 malocclusion who had completed orthodontic treatment met the inclusion criteria and were selected, and all of their 160 maxillary incisors were classified into two categories, namely R&Tp group and R&Tq group, according to their actual retraction pattern. Pre- and post-treatment CBCT images and 3D measurement software were used to measure and analyze tooth retraction and alveolar bone height and thickness changes within each group and to compare treatment changes of teeth and alveolar bone between two groups. Results • Anterior teeth in each group were intensively retracted and uprighted, with a longer retraction distance of incisal edge and a greater retraction angle of teeth in R&Tp group than in R&Tq group (both P=0.000). Alveolar bone thickness was significantly decreased at L3 and P1 in R&Tp group (both P<0.05), while it was significantly decreased at P1 and P2 in R&Tq group (both P<0.05). Total alveolar bone thickness decreased at T1 in R&Tp group (P=0.000) and at all levels in R&Tq group (all P=0.000). Finally, alveolar ridge height in two groups dropped both in the buccal (both P=0.000) and palatal (both P=0.000) sides, with a more prominent extent in the palatal side, and ridge height dropped most in palatal side of the teeth in R&Tq group. Conclusion • The buccal root apex area and the palatal alveolar ridge area of alveolar bone in the R&Tp group and the cervical and middle area of incisor root in palatal side of alveolar bone in the R&Tq group are high-risk areas for alveolar bone resorption when anterior teeth in teenagers with Angle's class Ⅱ division 1 malocclusion are intended to have en masse retraction.

Plug-Assisted Retrograde Transvenous Obliteration for the Treatment of Gastric Varices: The Role of Intra-Procedural Cone-Beam Computed Tomography

OBJECTIVE: To investigate the technical and clinical outcomes of plug-assisted retrograde transvenous obliteration (PARTO) for the treatment of gastric varices (GV) and to evaluate the role of intra-procedural cone-beam computed tomography (CBCT) performed during PARTO to confirm its technical success. MATERIALS AND METHODS: From January 2016 to December 2016, 17 patients with GV who had undergone PARTO were retrospectively evaluated. When the proximal part of the afferent vein was identified on a fluoroscopy, non-contrast CBCT images were obtained. In patients with incomplete embolization of GV, an additional injection of gelatin sponges was performed. Follow-up data from contrast-enhanced CT and upper intestinal endoscopy, as well as clinical and laboratory data were collected. RESULTS: Plug-assisted retrograde transvenous obliteration procedures were technically successful in all 17 patients. Complete embolization of GV was detected on CBCT images in 15 patients; whereas, incomplete embolization was detected in two. Complete embolization of GV was then achieved after an additional injection of gelatin sponges in these two patients as demonstrated on the 2nd CBCT image. The mean follow-up period after PARTO was 193 days (range, 73–383 days). A follow-up CT obtained 2–4 months after PARTO demonstrated marked shrinkage or complete obliteration of GV and portosystemic shunts in all 17 patients. There were no cases of variceal bleeding during the follow-up. CONCLUSION: Plug-assisted retrograde transvenous obliteration is technically and clinically effective for the treatment of GV. In addition, intra-procedural CBCT can be an adjunct tool to fluoroscopy, because it can provide an immediate and accurate evaluation of the technical success of PARTO.

Three-dimensional study on symmetry of the first molar and its peripheric alveolar bone in skeletal class Ⅲ patients with mandibular deviation / 上海交通大学学报（医学版）

Objective·To compare the difference of the first molar and alveolar morphology between the deviated side and non-deviated side in skeletal class Ⅲ patients with mandibular deviation by using cone-beam computed tomography (CBCT) image combined with three-dimensional reconstruction measurement technology. Methods·Fifty-six asymmetric CBCT data were evaluated by Mimics 10.0 and 3-Matic software. Some measures were analyzed by t-test including the buccolingual angle, the mesiodistal angle, crown root ratio of first molar and the thickness of alveolar or cancellous bone. Results·The buccolingual angle and crown root ratio of mandibular first molar were significantly larger on the deviated side than on the non-deviated side (P=0.021, P=0.004). Compared with the non-deviated side, the buccal and total cancellous bone thickness of mandibular first molar were significantly smaller on the deviated side (P=0.043, P=0.048). There was no significant difference in the ratio of buccal and total cancellous bone thickness on mandibular first molar (both P=0.118). The measurements of maxillary first molar and maxillary alveolar bone morphology were not significantly different between two sides (all P>0.05). Conclusion·In skeletal class Ⅲ patients with mandibular deviation, although the buccolingual compensation of first molar is found, the position of first molar in the alveolar bone is symmetrical. The asymmetry of alveolar bone morphology are mainly manifested in the reduction of the buccal and total cancellous bone thickness on the mandibular deviated side.

Remoção de terceiro molar superior deslocado para o espaço bucal / Removal of upper third molar displaced to the buccal space

Os autores descrevem um caso clínico de deslocamento de germe dentário de terceiro molar superior esquerdo para o espaço bucal em um paciente de 13 anos de idade. A localização do dente em posição profunda com envolvimento do corpo adiposo do bucinador dificultou a sua localização, ainda não descrita, nas condições em questão, na literatura. Com a Tomografia Computadorizada de Feixe Cônico (TCFC), foi possível localizar o dente deslocado e planejar a sua remoção. Os riscos e benefícios das extrações de germes de terceiros molares precisam ser avaliados devido ao grande risco de deslocamentos... (AU)

The authors describe a case of displacement of left upper third molar tooth germ to the buccal space in a patient 13 years old. The deep position of the tooth with involvement of the fat body of the buccinator made it difficult its location, still not described, under the concerned conditions, in the literature. With the cone beam computed tomography (CBCT), it was possible determine the location of the tooth and plan his removal. The risks and benefits of third molar tooth germ extraction should be evaluated because there is a greater chance of displacement... (AU)

Correlation between pain and degenerative bony changes on cone-beam computed tomography images of temporomandibular joints / 대한악안면성형재건외과학회지

BACKGROUND: The aim of this study was to assess correlation between pain and degenerative bony changes on cone-beam computed tomography (CBCT) images of temporomandibular joints (TMJs). METHODS: Two hundred eighty-three temporomandibular joints with degenerative bony changes were evaluated. Pain intensity (numeric rating scale, NRS) and pain duration in patients with degenerative joint disease (DJD) were also analyzed. We classified condylar bony changes on CBCT into five types: osteophyte (Osp), erosion (Ero), flattening (Fla), subchondral sclerosis (Scl), and pseudocyst (Pse). RESULTS: Degenerative bony changes were the most frequent in the age groups of 10~19, 20–29, and 50~59 years. The most frequent pain intensity was “none” (NRS 0, 34.6%) followed by “annoying” (NRS 3–5, 29.7%). The most frequent condylar bony change was Fla (219 joints, 77.4%) followed by Ero (169 joints, 59.7%). “Ero + Fla” was the most common combination of the bony changes (12.7%). The frequency of erosion was directly proportional to NRS, but the frequency of osteophyte was inversely proportional. The prevalence of Ero increased from onset until 2 years and gradually decreased thereafter. The prevalence of Osp, Ero, and Pse increased with age. CONCLUSIONS: Osp and Ero can be pain-related variables in degenerative joint disease (DJD) patients. “Six months to 2 years” may be a meaningful time point from the active, unstable phase to the stabilized late phase of DJD.

Eatimation of effective doses from a dental cone beam computed tomographic scanner / 中华放射医学与防护杂志

Objective To calculate effective dose based on the dose-area Product (DAP) measured in dental cone beam computed tomograhic (CBCT) scanning and using a conversion coefficient.Methods The method of the DAP was used to calculate the effective dose from KODAK 9500 dental CBCT scanner with fields of view (FOV) of 16 cm×15 cm and 12 cmu×8 cm.The DAP-values (mGy · cm2) were measured using a transmission ionization chamber connected to an electrometer (Doseguard 100,RTI Electronics AB,Sweden) and the chamber was placed directly on the exit of the X-ray tube.All measurements were repeated three times and averaged on each FOV data.The conversion coefficient of 0.080 μSv/mGy · cm2 was used to estimate the effective dose on the basis of DAP values,which was quoted from a literature.Results DAP values were found between the two FAOs to vary from 512 to 1 083 mGy · cm2,and the effective doses calculated with 0.080 μSv/mGy · cm2were 41 to 87 μSv.The effective doses given in this paper was lower than those reported in other literatures.Conclusions DAP measurement was found to be well defined and easy-to-use method of determining effective dose for some CBCT Units.However,determination of specific conversion coefficient in the CBCT must be further developed.

Correlations of pulp chamber height and dentine thickness of mandibular first molar with age in Chinese Han population based on cone beam computed tomography / 实用口腔医学杂志

Objective:To investigate the relationship between pulp chamber height and dentine thickness of mandibular first molar on long axis with age in a Chinese Han population by cone-beam computed tomography(CBCT).Methods:CBCT images of 420 Chinese Han subjects(210 males and 210 females) were divided into 6 age groups as follows:15-24,25-34,35-44,45-54,55-64 and 65-74 years(n=70,35 males and 35 females).The height of pulp chamber and dentine thickness of the chamber root and floor of mandibular first permanent molar on long axis was measured by Galileo software of CBCT in vertical direction and then statistical analysis was carried out.Results:On long axis,the height of pulp chamber was (0.85±0.54) mm in males and (0.79±0.51) mm in females(P>0.05);dentine thickness of the pulp chamber roof was (3.60±0.49) mm in males and (3.50±0.49) mm in females(P>0.05);and dentine thickness of the pulp chamber floor was (2.57±0.52) mm in males and (2.49±0.5) mm in females(P>0.05).With aging,the height of pulp chamber was decreased(P<0.05) and dentine thickness of mandibular first permanent molar on long axis was increased(P<0.05).Conclusion:In Chinese Han population,the of pulp chamber height of mandibular first permanent molar on long axis is related to age,The dentine thickness increased with ages,the increase of dentine thickness of pulp chamber floor is more significant than that of the roof.

Root canal system in permanent anterior teeth studied by cone beam computed tomography / 实用口腔医学杂志

Objective:To study the root canal system in permanent anterior teeth by cone-beam computer tomography(CBCT).Methods:12 85g anterior teeth in 1 103 patients were divided into group A(≤40 years) and group B(＞40 years).The CBCT images of 6 404 maxillary anterior teeth and 6 454 mandibular anterior teeth were collected.The number of roots and root canals,crown-root length,the types of root canal configurations,symmetry,age-related changes and gender differences were analyzed statistically.The correlation of double root canals system in mandibular anterior teeth were compared.Results:All of the maxillary anterior teeth and mandibular incisors had only one root while 1.66％ double roots were found in canines.The prevalence of double root canals in maxillary and mandibular anterior teeth were 0.03％ and 11.25％ respectively,that of the lateral incisors was the highest(17.40％).Type Ⅰ was the most frequent type (88.75％) in permanent anterior teeth followed by Type Ⅲ (7.07％).There was symmetrical distribution of the bilateral root canals of anterior teeth.There was no statistical significance of crown-root length among different age groups in permanent teeth (P ＞ 0.05).The variation of the root canal rate increased gradually at the age of 18-50 years,decreased gradually after the age of 50.The incidence of double root canals was higher in males (13.12％)than in females (9.93 ％) in mandibular anterior teeth.The incidence of double root canals of mandibular central incisors was positively correlated with lateral incisors and canines respectively (P ＜0.05).Conclusion:The root canal morphology of mandibular anterior teeth is complicated.The prevalence of double root canals is symmetic,age-related and gender difference.

The application value of cone beam CT in the diagnosis of sialolithiasis / 实用口腔医学杂志

Objective:To find the better imaging method for the diagnosis of sialolithiasis by comparing the 3 different imaging methods.Methods:32 cases of salivary calculus were examined by sonography,X-ray and cone beam computed tomography(CBCT),the sensitivity,specificity,positive predictive value,negative predictive value were compared among the 3 methods.Results:The sensitivity and negative predictive value of cone beam computed tomography(95.8％ and 80％) was significantly higher than those of sonography(83.3％,50.0％) and X-ray(58.3％,20％)(P ＜ 0.05).Of three imaging methods there was no statistical difference in specificity and positive predictive value.Conclusion:CBCT is more sensitive than sonography or X-ray in the diagnosis of sialolithiasis.

Detection of maxillary second molar with two palatal roots using cone beam computed tomography: a case report

The purpose of this clinical report was to show anatomical variations in permanent maxillary second molar using computed tomography (CT). This case report describes the application of CT to detect the unusual root anatomy of maxillary second molar with 2 separate palatal roots for successful endodontic treatment procedures. The use of cone beam computed tomography (CBCT) can overcome the limitation of the periapical standard radiography caused by the overlap of buccal and secondary palatal roots.

Changes of maxillary teeth and maxilla following quad helix maxillary expansion observed by Cone-Beam CT (CBCT) / 实用口腔医学杂志

Objective:To evaluate dental and skeletal changes following slow maxillary expansion with quad helix using Cone-Beam computer tomography (CBCT).Methods:13 patients(5males and 8 females,mean age 14.38 ±2.22 years)requiring maxillary ex-pansion as a part of their comprehensive orthodontic treatment were included.Each patient had CBCT images taken pre-(T1 )and post-(T2)maxillary expansion with quad helix.Changes of the distances between bilateral canines,first premolars,second premo-lars,first molars,the width of basal bone and palatal suture were measured.paired t-test results were analyzed using SPSS 17.0 soft-ware.Results:The distances between the 4 bilateral teeth increased by (2.47 ±1.05)mm,(2.97 ±1.90)mm,(2.79 ±1.21) mm and (3.15 ±1.15)mm,the apical distances decreased by (1.19 ±0.40)mm,(2.12 ±0.68)mm,(2.02 ±0.65)mm and (1.34 ±0.63)mm,respectively.The inclination of the first molars were decreased by (4.45 ±2.86)°and (4.02 ±1.45)°on the left and right side respectively.The width of basal bone and palatal suture increased by (2.37 ±0.96)mm and (1.21 ±0.50)mm respectively,the differences between T1 and T2 were all statistically different(P <0.001).Conclusion:Quad helix expands maxil-lary arch by greater dental changes than by skeletal changes.