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Objective: To determine the positional relationship between impacted mandibular third molar(IMTM) and mandibular canal(MC) by CBCT. Methods: 664 IMTMs with root apexes contacted to MCs on panoramic radiograph were further examined by CBCT,the exact positional relationship between IMTMs and MCs was observed and analyzed by I-Dixel software. Results: The 664 cases were divided into lowly(6. 3％),intermediately(60. 7％) and highly(33. 0％) impacted groups by the depth of IMTMs in mandibulae showed on CBCT images. The distance(mm) from the root apexes of IMTMs to the intact superior wall of MCs(n = 329) in lowly, intermediately and highly impacted cases were 1. 39 ± 1. 38,1. 28 ± 1. 03 and 1. 79 ± 1. 54 respectively(P ＜ 0. 05). MCs on the buccal side,lingual side,under the IMTMs and between the root apexes were found in 49. 8％,12. 0％,36. 6％ and 1. 5％ of the cases; the MC wall deffect was found in 65. 8％,27. 5％ and 95. 0％ of the cases with the MCs under,on buccal and lingual side of the IMTMs, respectively(P ＜ 0. 001). Conclusion: CBCT examination is necessary for the determination of the positional relationship between MC canal and IMTM with the root apex cotacted or overlapped to MC.
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Objective:To evlauate the mandibular bone mineral density(BMD) in postmenopausal osteoporotic(PMO) women by cone beam CT(CBCT) and to explore its clinical application.Methods:The BMD of the lumbar vertebrae and mandibular bone of 45 postmenopausal women was examined and calculated by dual energy X-ray absorptiometry(DXA) and CBCT respectively.The subjects were grouped by BMD value of lumbar vertebrae (PMO group,T ≤-2.5;healthy control group,T ≥-1.0).Correlation of CBCT indexes CTI (S),CTI(I) and CTMI with DXA index BMD was analyzed.Results:26 subjects were grouped into PMO (BMD =0.623 ± 0.056) and 19 into healthy control(BMD =0.973 ± 0.055)(P ＜ 0.05).The mandbular BMD in PMO and control groups was 0.776 ± 0.133 and 0.850 ± 0.122 (P ＞ 0.05) respectively.In PMO group all the CBCT indexes of mandibular bone were higher than those in the control group (P ＜ 0.05),no correlation was found between the CBCT indexes and BMD (P ＞ 0.05),while the CBCT indexes of the lumbar vertebrae were positively correlated with the BMD (P ＜ 0.05).Conclusion:CBCT is more sensitive than DXA in the assessment of mandibular BMD in PMO subiects.
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Objective:To explore the value of cone beam CT(CBCT) scanning following parotid sialography in the diagnosis of chronic parotitis.Methods:20 cases of suspected chronic parotitis patients underwent parotid gland sialography followed by CBCT scanning.The images were observed by transverse plane,coronal plane,sagittal plane of multiplanar reconstruction (MPR) and 3D reconstruction.Results:The acinus and ducts system of parotid were clearly displayed from any orientation by MPR and 3D-reconstructed images.The images of 6 cases of chronic recurrent parotitis in CBCT sialography were charactered by punctiform dilatation in whole parotid gland,4 of them showed a normal ductal system,while 2 exhibited expression of ductal inflammation.The images of 14 cases of chronic obstructive parotitis showed irregular ductal dilatations and stenosis.Punctiform dilatations were found in 2 cases,and small filling defects (negative salivary calculi) in 3 cases.Conclusion:CBCT sialography is an effective clinical examination for the diagnosis and treatment chronic parotitis.
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Objective:To study the anatomical correlation between dental arch and the volume of upper airway in patients with obstruc-tive sleep apnea hypoventilation syndrome(OSAHS). Methods: Dental arch architecture and upper airway volume were measured by cone beam CT(CBCT) in the subjects with OSAHS(n=22) and without OSAHS(n=19). The correlation between dental arch and the supper airway volume in OSAHS patients was analyzed. Results:The length of the upper dental arch and the height of palate in OSAHS patients were larger than those of the controls(All, P<0. 05). Cross-sectional area of nasopharynx and retropalatal and the total volume of upper airway were negatively correlated with the palatal height and upper dental arch length(P<0. 05), while positively correlated with upper dental arch of molar regions(P<0. 05). Conclusion:The abnormal shape of upper dental arch is related to the airway vol-ume of nasopharynx and retropalatal region in patients with OSAHS.
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Objective:To investigate the efficiency of CBCT in the diagnosis of impacted maxillary anterior teeth and the treatment effect of different guided eruption methods. Methods:34 impacted maxillary anterior teeth in 30 patients were examined by panoramic films and CBCT, the dental crowns, root, eruption space and other related items were measured and compared between 2 examinations. 20 cases were treated by closed guided eruption and traction( CGET) technique, 10 cases by circumferential supracrestal fibrotomy and exposed traction( CSF-EE) , results were compared. Results: CBCT was more effective than panoramic films in the revelation of tooth root bending, apical pore closure and eruption measurements(P<0. 05). 7-10 d after treatment 5 out off the 10 casses treated by CSF-EE showed different degrees of clinical crown elongation, poor gum appearance and low height of alveolar ridge as insufficient periodontal attachment. However, the treatment of CGET for 26 teeth (76. 47% of all cases) was highly successful and received very satisfactory re-sults, the rest 8 teeth (23. 53% of all cases) showed mediocre satisfaction. Conclusion: CBCT can accurately display the position, shape, relation with adjacent teeth of the impacted teeth. Closed guided eruption and traction is more effective for the treatment.
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Objective:To study the morphological characteristics of temporo-mandibular joint with high angle vertical skeletal pattern in adult females with class II skeletal type.Methods:41 CBCT films of adult females (20 normal controls;21 skeletal class II high angle subjects)were collected.The position of and form of condyle,form of fossa and joint spaces were measured by Mimics 17.0 soft-ware.Results:Compared with the control group the condyles in high angle patients located more posterior.The joint fossae were lower. The angles of posterior joint node bevels were smaller.The condyles were shorter,thinner and tipped more anteriorly.The position of the conyles were more anteriorly.Conclusion:Class II skeletal type adult females with high vertical skeletal patterns have different forms of fossae,different positions and forms of condyle compared with the normal controls.
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Objective:To study the alveolar bone morphology in the anterior teeth area of the skeletal Class Ⅱ malocclusion subjects with different vertical skeletal types.Methods:64 patients with skeletal Class Ⅱ malocclusion and 15 subjects with normal occlusion were included.The alveolar bone structure of the anterior teeth were observed using CBCT.Results:The labial and lingual alveolar bone height and the alveolar bone thickness of the incisors of the patients were much lower than those of the normal controls.The height of labial and lingual alveolar bone and the alveolar bone thickness of anterior teeth in high-angle subgroup were lower than those in low-angle subgroup.Conclusion:The thickness of the anterior teeth alveolar bone of skeletal Class Ⅱ malocclusion is low,espe-cially in the high-angle group.
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Objective:To investigate the effects of corticotomy assisted orthodontic treatment for mild skeletal Class Ⅱ malocclusion. Methods:7 adult patients with mild skeletal Class Ⅱ division 1 malocclusion were included and underwent corticotomy assisted ortho-dontic treatments.3D measurements and analysis of CBCT data before and after treatment were conducted.Results:The average dura-tion of upper anterior teeth retraction was 3.2 months.After treatment,obvious retraction of up incisiors with the retraction of maxillary alveolar bone and the upper lip backward and downward movement were observed.Conclusion:Corticotomy assisted orthodontic treat-ment is effective in the treatment of mild skeletal Class Ⅱ malocclusion by the retraction of uper anterior teeth,alveolarar bone and soft-tissue profile improvement.
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Objective:To study the relationship between gingival thickness(GT)and the underlying alveolar bone thickness(BT)in maxillary anterior region and the distance from cemento-enamel junction(CEJ)to alveolar crest.Methods:30 young volunteers with healthy gingiva were included.GT was measured at 2mm below the CEJ,buccal BT were measured at 3 locations:2,4 and 6 mm below the alveolar crest respectively,the distance from CEJ to alveolar crest were measured by CBCT and clinical direct measure respectively. Results:The correlation coefficient (r)values between GT and BT at 2,4 and 6 mm below alveolar crest were 0.493,0.383 and 0.342 (P <0.001 )respectively,the r value between GT and the distance from CEJ to alveolar crest was -0.21 3(P <0.01 ).No statistically significant difference was observed between CBCT and clinical measurements(t =-0.521 ,P =0.603).Conclusion:There is positive correlation between GT and BT at 2,4 and 6 mm below alveolar crest and negative relation between GT and the distance from CEJ to alveolar crest.
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Objective:To analyze the 3D changes of pharyngeal airway in patients with skeletal Class Ⅲ malocclusion after rapid maxillary expansion(RME)and maxillary protraction.Methods:53 patients underwent orthodontic treatment with Hyrax palatal ex-panders and maxillary protraction.Cone-Beam computed tomography(CBCT)scan was taken before treatment(T0),after 1 6 d RME (T1 )and after about 5 month maxillary protraction(T2).Data were reconstructed into 3D model,sagittal and transversal measure-ments,cross sectional areas,volumes of the pharyngeal airway were computed.Results:After RME,the transversal measurements, cross sectional areas,volumes of nasal passage were increased(P <0.05).After maxillary protraction,the 4 nasopharyngeal measure-ments were increased(P <0.05).Conclusion:RME and maxillary protraction may increase pharyngonasal airway.
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Objective:To study the morphologic standard values of craniofacial hard-tissue of the youths in Xi'an.Methods:CBCT scanned cephalometric data of 100 selected volunteers (50 males and 50 females)with individual normal occlusion were collected.31 landmarks and 31 measurements were compared between sexes and between 3D and 2D data with software InvivoDental 5.2,WinCeph 8.0.and SPSS 19.0.Results:1.In the 3D measurements,vertical growth of mandible in the females was more than that in the males. The values of torque of lower incisor,basis length,height of rumi mandibulae and length of corpora mandibulae in the males were bigger than those in the females.2.Compared with 2D measurements,there existed statistically significant differences in most parameters except U1-NA(mm).Conclusion:3D analysis with CBCT may provide more accurite morphologic data for craniofacial hard tissues.
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Most of the maxillary first premolar are single-rooted,there are also two-rooted and three-rooted ones.A case of three-rooted maxillary first premolar was diagnosed by CBCT.CBCT has the advantage in the observation of the variation root number,root canal bending and the variation of root canal morphology.
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Objective:To investigate the root and canal morphology of mandibular first permanent molars in adolescents by cone-beam computered tomography (CBCT).Methods:366 mandibular first permanent molars in 1 83 adolescents aged 1 2 -1 6 years were examined by CBCT from July,201 2 to December,201 3.The age,sex,the number of roots and canals and canal morphology were re-corded.The data were statistically analyzed by software SPSS 1 9.0.Results:365 mandibular first permanent molars showed single mesial root except one with C-shaped root;282(77.05%)teeth had one distal root,83(22.68%)had two.356(97.27%)teeth had two mesial canals and 9(2.46%)had one.229(62.57%)teeth had one distal root with one canal,53(1 4.48%)had one distal root with two canals.83(22.68%)had two distal roots with one canal in each root,one (0.27%)had C-shaped root with three canals. There were no significant differences between males and females and between the two sides on the number of roots and number of ca-nals.Conclusion:Majority of mandibular first molars have two roots,the root change occurs in distal root.The prevalence of three-rooted mandibular first molars has no significant difference between genders and 2 sides.
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Objective:To study the changes of upper airway dimension and morphology in Class Ⅱ mandibular retrusion children af-ter functional treatment by Twin-block appliance.Methods:The Cone-Beam CT(CBCT)data of upper airway of the subjects were measured with Dolphin 11.5 software before and after fuctional treatment by Twin-block appliance.The comparison of upper airway di-mension and morphology between pre-treatment and post-treatment was performed by paired t-text.Results:After functional treatment the volume of total upper airway,velopharyngeal airway,glossopharyngeal airway,laryngopharyngeal airway,oropharyngeal airway,the sectional area of the inferior of the soft palate(SP),tip of the epiglotti(TE),the sagittal diameter of SP,the lateral diameter of SP and TE increased(P <0.05)in the children;the airway's shape of SP was attended to be rounder and TE to be more flat.Conclusion:Functional treatment is effective in the treatment of skeletal Class Ⅱ mandibular retrusion of children by increase of the upper airway and improvement of respiration.
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Objective:To investigate the structure of alveolar bone around incisors in patients with verical facial type of skeletal ClassⅡ by CBCT.Methods:60 skeletal Class Ⅱ patients were divided into low angle,average angle and high angle cases(n =20)by FMA.CBCT scanning was made and the thickness of the labial and lingual alveolar bone around the incisors in each subject was meas-ured.The measurements were analyzed using ANOVA.Results:The total width of alveolar bone at the root apical level of maxillary and mandibular incisors,the lingual thickness of alveolar bone at the root midpoint of maxillary incisors and labial thickness of alveolar bone at the root midpoint of mandibular incisors in the high angle cases were thinner than that in the average and low angle cases(P <0.05),but there was no significant difference in labial thickness of alveolar bone at the crest among 3 groups.Conclusion:The alveo-lar bone thickness around incisors of high angle patients is thinner,more attention should be paid for the alveolar bone absorpation and tooth root exposure in these patients.
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Objective To quantitatively evaluate the thickness of the buccal cortical bone in the posterior region of the maxillary for orthodontic micro‐implants in children .Methods Forty children (20 males and 20 females) in permanent dentition with Class Ⅱdivision 1 malocclusion were selected .The maxillary posterior alveolar bones of the subjects were scanned and reconstructed by cone‐beam computed tomography (CBCT) .The thickness of the cortical bone between the dental roots of the second upper premolar and the first upper molar at the height of 3 ,4 ,5 ,6 ,7 ,8 ,9 mm from the alveolar crest were determined .The data were analyzed sta‐tistically .Results The thickness of the cortical bone between the second upper premolar and the first upper molar was minimum at the height of 4 mm from the alveolar crest(P<0 .05) .The thickness of the cortical bone increased along with the distance increas‐ing from the alveolar crest at the height of 5 mm .The cortical bones in male were significantly thicker than those in female at the height of 7 ,8 ,9 mm (P<0 .05) .Conclusion The thickness of the buccal corticalbone in children in permanent dentition with ClassⅡ division 1 malocclusion changes with the measured vertical position .Micro‐implant anchorage is better to be placed in the area with a distance of 5 mm from the alveolar crest .
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Objective:To investigate the alveolar bone height change before and after retraction of anterior teeth in adult patients. Methods:A total of 15 adult patients with angle class I bimaxillary protrusion had 4 first premolars extracted followed by othodontic treatment for retraction of anterior teeth with straight arch wire techniques.Cone beam computed tomography(CBCT)scans were made before and 3 months after retraction.The labial and the lingual alveolar bone height around central and lateral incisors was measured and analyzed before and after treatment.Results:Significant increase of labial alveolar bone height around anterior teeth was found in both maxilla and mandible(P ＜0.05),however,lingual alveolar bone height was decreased(P ＜0.05).Conclusion:For bimaxillary protrusion patients,the lingual alveolar bone height decreased due to obvious incisors retraction in adults which should be considered carefully in orthodontic clinic.
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Objective To establish a three-dimensional digitized visible model to meet the clinical and research needs.Methods The head of the volunteer was scanned by a cone beam CT (CBCT).The bone tissue,the facial soft tissue and the teeth were extracted from the cone beam CT raw data according to the different Houns field values.The 3D digital craniofacial model was reconstructed from the three tissues extracted from the CBCT original data.The 3D dental model with high resolution was acquired by scanning the dental cast with the laser scanner.The 3D facial model with texture was acquired by scanning the volunteer's face directly by other laser scanner.With the regis tration algorithm in 3D graphics,the 3D facial model with texture and the 3D dental model with high resolution were transformed to the same coordinate which was of the 3D digital craniofacial model.Results We acquired a complicated 3D craniofacial digital model which combined the teeth model with high resolution,the bone model and the face model with texture.Conclusions The method is able to accurately establish the craniofacial digital model.
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PURPOSE: On-line image guided radiation therapy (on-line IGRT) and (kV X-ray images or cone beam CT images) were obtained by an on-board imager (OBI) and cone beam CT (CBCT), respectively. The images were then compared with simulated images to evaluate the patient's setup and correct for deviations. The setup deviations between the simulated images (kV or CBCT images), were computed from 2D/2D match or 3D/3D match programs, respectively. We then investigated the correctness of the calculated deviations. MATERIALS AND METHODS: After the simulation and treatment planning for the RANDO phantom, the phantom was positioned on the treatment table. The phantom setup process was performed with side wall lasers which standardized treatment setup of the phantom with the simulated images, after the establishment of tolerance limits for laser line thickness. After a known translation or rotation angle was applied to the phantom, the kV X-ray images and CBCT images were obtained. Next, 2D/2D match and 3D/3D match with simulation CT images were taken. Lastly, the results were analyzed for accuracy of positional correction. RESULTS: In the case of the 2D/2D match using kV X-ray and simulation images, a setup correction within 0.06degrees for rotation only, 1.8 mm for translation only, and 2.1 mm and 0.3degrees for both rotation and translation, respectively, was possible. As for the 3D/3D match using CBCT images, a correction within 0.03degrees for rotation only, 0.16 mm for translation only, and 1.5 mm for translation and 0.0degrees for rotation, respectively, was possible. CONCLUSION: The use of OBI or CBCT for the on-line IGRT provides the ability to exactly reproduce the simulated images in the setup of a patient in the treatment room. The fast detection and correction of a patient's positional error is possible in two dimensions via kV X-ray images from OBI and in three dimensions via CBCT with a higher accuracy. Consequently, the on-line IGRT represents a promising and reliable treatment procedure.