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Conventional radiography is the mainstay for evaluation of developmental and pathologic disorders of oral and maxillofacial structures. Occasionally, clinicians may experience diagnostic pitfalls during interpretation of these imaging modalities. The aim of this article is to present 4 cases of pseudopathologic disorders found on intraoral and panoramic radiographs. Subsequent use of cone beam computed tomographic (CBCT) imaging determined that the initial concerning findings represented anatomical or radiographic anomalies rather than pathologic processes. Supplemental use of CBCT scans may enhance diagnostic assessment, possibly reducing the need for surgical intervention, and elucidate structurally compromised regions of the jaw that could predispose it to fracture. [ABSTRACT FROM AUTHOR]

To evaluate the axial and dimensional changes of the condylar head after orthognathic surgery, including Le Fort I and bilateral sagittal split ramus osteotomies, and to assess condylar remodeling through three-dimensional (3D) surface superimposition. Twenty-four patients (15 females, 9 males; mean age: 32.22 ± 6.92 years) with skeletal Class III deformity were included in the study. Cone-beam computed tomography data obtained in the preoperative (T0) and postoperative (T1) periods were examined using Mimics and 3-Matic software. The height, depth, and width of the condylar head and its angular changes were measured. The volumes of the 3D reconstructed models were calculated, and remodeling amounts were evaluated through regional surface superimposition. Statistical significance was set at P <.05. Following the surgery, there was a significant decrease in the size of condyles (P <.05). An inward rotation of the condyles was found in the axial plane (T0: 79.60 ± 6.01°, T1: 76.6 ± 6.48°, P <.05). The maximum resorption, maximum apposition, mean remodeling, and mean absolute remodeling were −2.63 ± 1.23 mm, 1.15 ± 0.4 mm, −0.30 ± 0.34 mm, and 0.73 ± 0.43 mm, respectively. No correlation was found between the angular changes and remodeling parameters or linear and volumetric changes of the condylar head (P >.05). Condyles undergo a remodeling process with a resorptive character following orthognathic surgery, without clinically significant effects in the present study. [ABSTRACT FROM AUTHOR]

Studies on negation in the school of Vyākaraṇa have focused on the early period of its development, especially on the interpretation of prasajya and paryudāsa types of negation provided by early commentators starting with Patañjali and elaborated on by Bhartṛhari. The post-Bhartṛhari period requires thorough research when it comes to the theory of meaning and cognition proposed by Indian grammarians. The present article analyses the interpretation of negation proposed by Kauṇḍabhaṭṭa in the Vaiyākaraṇabhūṣaṇasāra and shows it against the background of theory of negation that had been developing for centuries within the school of Vyākaraṇa. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the pre- and postoperative position and dimensions of the inferior alveolar canal (IAC) following sagittal split osteotomy (SSO) and identify any association with postoperative neurosensory deficit (NSD) at 1 year. This retrospective cohort study enrolled consecutive patients who had SSO performed to correct skeletal malocclusion. The pre- and postoperative cone beam computed tomography data were superimposed to visualize differences in IAC position and dimensions. Subjective and objective neurosensory tests were used to determine NSD in the inferior alveolar nerve distribution. A total of 20 subjects were included. The preoperative distance from the lateral cortex of the IAC to the inner aspect of the lateral cortex of the mandible was significantly greater in sides with NSD when compared to sides without NSD (P = 0.01). A significantly greater reduction in the postoperative distance measurement was seen in sides with NSD when compared to sides without NSD (P = 0.01). The magnitude of mandibular movement was significantly increased in sides with NSD (P = 0.02). The preoperative location of the IAC, as well as certain changes in the mediolateral and vertical positions as a result of SSO, are risk factors for postoperative NSD. [ABSTRACT FROM AUTHOR]

This study analyzed the trueness of polymer-infiltrated ceramic and glass ceramic crowns manufactured using the chairside computer-aided design/manufacturing (CAD/CAM) system. The master model designs crowns using a CAD program after acquiring a digital impression with an intraoral scanner. Vita Enamic (VE), Vita Suprinity (VS), and IPS e.max CAD (IPS) were used to manufacture 10 crowns each (total: 30 crowns), using the chairside CAD/CAM system (inLab MC XL). Trueness was evaluated by superimposing the CAD data on the scan data using a three-dimensional program. The Kruskal–Wallis H test, a nonparametric test, and the Mann–Whitney U test were performed by applying the significance level (0.05/3 = 0.016), which was adjusted by post-analysis Bonferroni testing. There was a significant difference in the trueness between the samples (p < 0.05). However, there was no statistically significant difference in the outer surface trueness between the samples (p > 0.05). These findings show that the milling accuracy of VE is better than that of VS and IPS. [ABSTRACT FROM AUTHOR]

Purpose: The objective of the present study was to investigate the usefulness of high-output Erbium:Yttrium,Aluminum, Garnet (Er:YAG) laser in pulp cavity perforation, chamber roof removal, and root canal orifice enlargement. Materials and Methods: Seventy extracted human incisors without curvature were used. Using an Er:YAG laser system (2940 nm, Smart 2940D, DEKA; Florence, Italy), chamber roof removal and root canal orifice enlargement were performed. A total of 14 subgroups, including two control groups, were formed. The following three laser application tips were used: mirror, sapphire, and spear-shaped sapphire (spear). Laser output was set at either 5 or 7 W. Time required for dental tissue removal was measured and statistically analyzed using Kruskal-Wallis and Fisher's PLSD tests. After laser application, x-ray imaging, stereomicroscopy, and scanning electron microscopy were performed. Results: In teeth without crowns, the time required for root canal orifice enlargement was clearly shorter with the mirror tip. In teeth with crowns, the root canal was enlarged almost up to the apical third of the root, and when using the mirror tip, a V-shaped hole was created. In teeth without crowns, a U-shaped hole was made almost up to the center of the root. SEM showed hardly any smear layer on the cut surface of the root canal wall. Conclusion: Root canal preparation should be carried out by applying high-output Er:YAG laser using a spear tip. [ABSTRACT FROM AUTHOR]

Abstract Superimposition of radiographic imaging is used to evaluate patient growth and the effects of surgical and/or orthodontic treatment. The purpose of this study was to compare the outcomes of superimposition between two-dimensional (2D) and three-dimensional (3D) superimpositions. 2D lateral cephalograms were generated from the initial and final cone beam computed tomography scans (CBCT) of 18 patients and superimposed. Both 3D CBCT and 2D CBCT generated lateral cephalograms were oriented to the Frankfort horizontal plane and superimposed according to the American Board of Orthodontics recommendations. Changes in landmark position were quantified from the resulting superimposition outcomes via linear measurements made with Dolphin software. Differences between the two methods were analyzed using paired t -tests. Measurements were repeated twice for 10 randomly selected scans to assess reliability by intra-class correlation coefficient (ICC) analysis. Intra-examiner reliability was high for all measurements (ICC > 0.84). Agreement between 2D and 3D superimposition outcomes, as measured by P -values, was low for ANS (P = 0.026), B-point (P < 0.001), ST Upper lip (P = 0.019), U1 tip (P = 0.010), and U1 apex (P = 0.026). 2D measurements were significantly higher than 3D measurements for ANS, B-point, ST Upper lip, U1 tip, and U1 apex. Findings indicated that both methods of superimposition (2D and 3D) are highly reliable. Statistical differences between 2D and 3D superimposition outcomes were below the threshold of clinical significance. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this systematic review was to synthesize the available literature concerning the reliability of three-dimensional superimposition methods when assessing changes in craniofacial hard tissues. Materials and Methods: Four electronic databases were searched. Two authors independently reviewed potentially relevant articles for eligibility. Clinical trials, cohort, case-control, and crosssectional studies that evaluated the reliability of three-dimensional superimposition methods on the anterior cranial base were included. Results: Six studies fulfilled the inclusion criteria. Four studies used the voxel-based registration method, one used the landmark-based method and one used the surface-based method. Regarding reliability, the voxel-based studies showed on average a difference of 0.5 mm or less between images. The optimized analysis using a six-point correction algorithm in the landmarkbased method showed 1.24 mm magnitude of error between images. Conclusions: Although reliability appears to be adequate, the small sample size and high risk of bias among studies make available evidence still insufficient to draw strong conclusions. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Our aim was to assess the accuracy of computer-aided orthognathic surgery for maxillary repositioning in 15 patients with mandibular hyperplasia and normal temporomandibular joints (TMJ). We aligned preoperative and postoperative virtual skulls at the cranium using surface superimposition then recorded and calibrated three 3-dimensional coordinates (maxillary dental landmarks U0, 6R, and 6L) on the skulls. Errors between these preoperative and postoperative landmarks were calculated and the largest error of every patient was chosen for assessment. Landmark errors ranged from 1.00 – 2.49 mm, and recording errors from −0.06 – 0.07 mm. The superimposition error was mean (SD) 0.036 (0.002) mm. The accuracy of the method is acceptable in patients with a normal TMJ. [ABSTRACT FROM AUTHOR]

Introduction: Computer software allows a photograph of patient’s face and a photograph of their dental casts to be combined into one image, similar to that seen in a lateral cephalogram. The aim of this study was to assess the agreement between the measurements carried out on this novel composite photographic image and those taken from a lateral cephalogram of the same patient. Methods: The method involved the superimposition of a photograph of a patient’s dental casts onto a photograph of their profile thus creating a composite image. The position of teeth in relation to the face was then compared on these images and on lateral cephalograms. The distances between a number of facial reference points to the upper right central incisor and the upper right last molar, were measured on both images. Results: The records of 34 participants showed that there was good or acceptable agreement between measurements carried out on composite images and on lateral cephalograms. This agreement was generally better for measurements carried out from the reference points to the incisor tooth than to the molar. However, standard deviations of the mean differences between measurements were relatively high. Conclusions: The photographic superimposition method eliminates exposure to ionizing radiation and is relatively inexpensive. However, it is not reliable enough to deliver accurate information on the position of teeth in the face. [ABSTRACT FROM AUTHOR]

Purpose This Technical Procedure describes a novel workflow for a one-step formation of the supra-implant emergence profile in the esthetic zone – the ‘Digitally Flip Technique’ (DFT). Methods After implant placement, a post-operative intra-oral optical scan (IOS) was performed to capture the final three-dimensional implant position. Based on the superimposition of the digitally slice-wise DICOM-segmentation of the digitally flipped (mirrored) contra-lateral tooth and the STL-file of the IOS, an individualized healing abutment was CAD/CAM-fabricated out of PMMA-based restoration material in a fully digital workflow and seated at the stage of reopening surgery. One single treatment step was necessary for final modulation of the supra-implant mucosa architecture in order to mimic the morphological emergence profile of the contra-lateral tooth within a short-span time frame of four days after insertion of the individualized healing abutment. Conclusions The implant crown emergence profile could be shaped immediately after reopening according to the three-dimensional radiographic contour of the digitally flipped contra-lateral tooth. Estimating the emergence profile or time-consuming step-by-step conditioning of the mucosa through an additionally produced implant provisional was therefore avoided. [ABSTRACT FROM AUTHOR]

Purpose The present study tested the hypothesis that the type of anterior tooth movement is correlated with the height level of the power arm with respect to the center of resistance (CRe) of a tooth, but not with the power arm length itself in sliding mechanics using three-dimensional (3D) model analysis. Materials and methods Anterior teeth were retracted with sliding mechanics using power arms of different lengths in five subjects with maxillary protrusion. Anterior tooth movements during three months’ retraction were assessed by means of 3D model analysis, and the relationship between the power arm length and the distance from the center of rotation (CRo) to CRe, and the relationship between the distance from the level of the power arm hook to CRe and the CRo-CRe distance were evaluated. Results The height level of the power arm relative to CRe was significantly correlated with the CRo-CRe distance, but there was no significant correlation between the power arm length and the CRo-CRe distance. Conclusion Anterior tooth movement during retraction varied with the anatomical parameters of individual patients, even if the same power arm length was employed. The present findings suggest that the height level of the power arm relative to CRe is the most influential factor determining the tooth movement, while the power arm length itself has less impact on subsequent tooth movement. Therefore, it is recommended that an optimal power arm length be calculated back from the location of CRe at the beginning of treatment and treatment progress be monitored using 3D model analysis. [ABSTRACT FROM AUTHOR]

Purpose The present study aimed to establish a method for qualitatively and quantitatively determining tooth movement by integrating three-dimensional (3D) model analysis and cephalometric analysis. Materials and methods Superimposition of 3D images of dental casts before and after orthodontic treatment was performed in two steps. First, initial and final 3D images of dental casts were superimposed at the central incisor and then the reference axis of the incisor was constructed. Second, another superimposition was carried out at the medial points of the third palatal rugae and the palatal vault. The changes in the inclination of the central incisor were measured using an established method of 3D model analysis and cephalometric analysis. The error of measurement in 3D model analysis was compared with that in cephalometric analysis. Results There was no significant difference in the degree of incisor tipping between times (Time 1 and Time 2) for cephalometric analysis and 3D model analysis, and between the averaged (Time 1 and Time 2) measurements from cephalogram and the 3D model. The error of measurement for 3D model analysis was 0.58°, and the 95% confidence interval (CI) was [−0.62, 0.62]. Corresponding values for cephalometric analysis were 2.02° and [−1.49, 2.73], respectively. Conclusion The 3D model superimposition method established in the present study was found to be reliable enough to determine the degree of tipping and the location of the center of rotation of the incisor before and after orthodontic treatment. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. Methods: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class 11 patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. Results: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. Conclusions: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods. [ABSTRACT FROM AUTHOR]

Facial onlay augmentation is often performed as an ancillary procedure simultaneously with orthognathic surgery to improve facial appearance, with hydroxyapatite (HAp) and HAp-based composites often used as the materials of choice. The ability to apply HAp in a granular rather than solid shape form may be responsible for its comparatively reduced rate of complications. However, a known complication of HAp and HAp composites is reduction of implant volume over time associated with resorption of the material. Evaluation of the volumetric changes of implanted biphasic calcium phosphate (HAp/β-TCP)/collagen composite in the malar areas from baseline to 4 months, 9–12 months, and 18–24 months after surgery using cone beam computed tomography (CBCT) surface superimposition and volumetric subtraction was done. The average decrease of volume of implanted HAp/β-TCP 4 months after surgery was 18.6%. Further volumetric decreases were negligible and a mean total volume loss of 21.65% was found at 18–24 months postoperatively. [ABSTRACT FROM AUTHOR]

Objective: To describe a newly developed three-dimensional (3D) digital superimposition method for quantitative evaluation of tooth wear that occurs during orthodontic treatment. Materials and Methods: The sample consisted of dental casts obtained from 56 patients (23 male patients and 33 female patients; mean ± standard deviation age = 21.8 ± 5.1 years) who received orthodontic treatment with extraction of four premolars. The maxillary and mandibular dental casts taken before (T1) and after (T2) orthodontic treatments were scanned, and 3D images of the canines were constructed. The canines at T1 were superimposed with those at T2 with the best-fit method using the middle third of the labial and lingual surface as the reference area. To measure the volume of the canines, four boundary planes were constructed, and the differences in volume before and after orthodontic treatment were calculated. Results: The mean volume of tooth wear of the 224 canines was 2.0 mm³ after 35.5 months of orthodontic treatment. The volume of canine tooth wear was 2.3 ± 1.5 mm³ in male subjects and 1.9 ± 1.2 mm3 in female subjects. The mean wear of the upper right canines (2.4 ± 2.0 mm³) was significantly greater than that of the lower right canines (1.9 ± 2.6 mm³). Conclusions: Regional registration of teeth in 3D digital models is useful for quantitative evaluation of tooth wear in orthodontic patients. This method may also be used to assess treatment results in restorative dentistry [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of postoperative condylar axis changes on mandibular condylar remodeling by comparing the condylar head in three-dimensional (3D) surface reconstructions before and after surgery in skeletal Class III deformities (one-jaw [mandibular setback] or two-jaw surgery), and also to determine the relationship between condylar inward rotation and condylar surface remodeling after orthognathic surgery. Materials and Methods: A retrospective analysis was conducted of 30 patients with skeletal Class III deformities who had received orthognathic surgery. Group 1 underwent one-jaw surgery (10 men, five women, age 22.4 ± 3.3 years), and group 2 underwent two-jaw surgery (10 men, five women, age 22.3 ± 2.2 years). Sixty condyles were reconstructed and superimposed pre- and postoperatively to compare the changes of condylar surfaces. The relation between the condylar axis change and the surface change using the Pearson correlation were investigated from the 3D image software. Materials and Methods: A retrospective analysis was conducted of 30 patients with skeletal Class III deformities who had received orthognathic surgery. Group 1 underwent one-jaw surgery (10 men, five women, age 22.4 ± 3.3 years), and group 2 underwent two-jaw surgery (10 men, five women, age 22.3 ± 2.2 years). Sixty condyles were reconstructed and superimposed pre- and postoperatively to compare the changes of condylar surfaces. The relation between the condylar axis change and the surface change using the Pearson correlation were investigated from the 3D image software. Conclusion: After orthognathic surgery, condylar surface changes occurred, and condylar inward rotation was closely related to changes of condylar surface. [ABSTRACT FROM AUTHOR]

Abstract: This paper demonstrates a case of personal identification that initially seemed straightforward, mainly because complete and comprehensive antemortem dental records of a missing person were made available for analysis. Skeletal remains were found and the skull (most crucial for human identification) was delivered for analysis. Comparative analysis of antemortem and postmortem dental records excluded identification, while the results of superimposition (simultaneously performed by another team member) revealed sufficient concordant points to establish identity. The results caused confusion and additional information was required. The need for more evidence resulted in delivery of elements of the postcranial skeleton. Identification was finally achieved when concordant points were established in a comparison of antemortem X-rays and the humerus. Team members concluded that the dental records were in fact not adequate and that mistakes in numbering the teeth (superior canine instead inferior canine and right and left premolars) were considered to be the initial reason a positive identification had not been made. The authors conclude that a multidisciplinary approach is crucial to making a positive identification and that caution should be exercised when carrying out personal identification from dental records alone. The need to adequately train police officers to collect and preserve dental evidence is also emphasized. [Copyright &y& Elsevier]

During cone beam computed tomography (CBCT) scanning, intra-oral metallic objects may produce streak artefacts, which impair the occlusal surface of the teeth. This study aimed to determine the accuracy of replacement of the CBCT dentition with a more accurate dentition and to determine the clinical feasibility of the method. Impressions of the teeth of six cadaveric skulls with unrestored dentitions were taken and acrylic base plates constructed incorporating radiopaque registration markers. Each appliance was fitted to the skull and a CBCT performed. Impressions were taken of the dentition with the devices in situ and dental models were produced. These were CBCT-scanned and the images of the skulls and models imported into computer-aided design/computer-aided manufacturing (CAD/CAM) software and aligned on the registration markers. The occlusal surfaces of each dentition were then replaced with the occlusal image of the corresponding model. The absolute mean distance between the registration markers in the skulls and the dental models was 0.09±0.02mm, and for the dentition was 0.24±0.09mm. When the method was applied to patients, the distance between markers was 0.12±0.04mm for the maxilla and 0.16±0.02mm for the mandible. It is possible to replace the inaccurate dentition on a CBCT scan using this method and to create a composite skull which is clinically acceptable. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to develop a reference frame for three dimensional (3D) facial soft tissue growth analysis in children and to determine its reproducibility. Two observers twice placed the reference frame on 39 3D-stereophotogrammetry facial images of children with orofacial clefts and control children. The observers’ performances were analyzed by calculating mean distance, distance variability, and P95 between the same facial surfaces at two different time points. Correlations between observers were analyzed with Pearson''s correlation coefficient. The influence of presence of a cleft, absence of one ear in the photograph, and age on the reproducibility of the reference frame was checked using Student''s t test. Results of intraobserver comparisons showed a mean distance of <0.40mm, distance variability of <0.51mm, and P95 of <0.80mm. For interobserver reliability, the mean distance was <0.52mm, distance variability was <0.53mm, and P95 was <1.10mm. Presence of a cleft, age, and absence of one ear on the 3D photograph did not have a significant influence on the reproducibility of placing the reference frame. The children''s reference frame is a reproducible method to superimpose on 3D soft tissue stereophotogrammetry photographs of growing individuals with and without orofacial clefts. [Copyright &y& Elsevier]

Abstract: Forensic dentistry plays a major role in body identification. The dental examination is very accurate and also, nowadays, in the time of a comprehensive fingerprint and DNA assessment, objectively supported. The identification, which is based on the dental documentation, leads up to 43–89% of a successful process. The purpose of the study is to describe the techniques employed by forensic odontology to identify human remains and also to provide details of some of the novel developments within this area. Comparative methods of dental identification of the unknown subject with pre-mortem clinical records, X-ray images, implant presence, superimposition and DNA analysis confirm the identity of the individual. It was shown that dental identification of a person is based on unique individual characteristics of the dentition and dental restorations, relative resistance of the mineralised dental tissues and dental restorations to changes resulting from decomposition and harsh environmental extremes such as conditions of temperature and violent physical forces. [Copyright &y& Elsevier]

Objective: The purpose of this study was to develop superimposition method on the lower arch using 3-dimensional (3D) cone beam computed tomography (CBCT) images and orthodontic 3D digital modeling. Methods: Integrated 3D CBCT images were acquired by substituting the dental portion of 3D CBCT images with precise dental images of an orthodontic 3D digital model. Images were acquired before and after treatment. For the superimposition, 2 superimposition methods were designed. Surface superimposition was based on the basal bone structure of the mandible by surface-to-surface matching (best-fit method). Plane superimposition was based on anatomical structures (mental and lingual foramen). For the evaluation, 10 landmarks including teeth and anatomic structures were assigned, and 30 times of superimpositions and measurements were performed to determine the more reproducible and reliable method. Results: All landmarks demonstrated that the surface superimposition method produced relatively more consistent coordinate values. The mean distances of measured landmarks values from the means were statistically significantly lower with the surface superimpositions method. Conclusions: Between the 2 superimposition methods designed for the evaluation of 3D changes in the lower arch, surface superimposition was the simpler, more reproducible, reliable method. [ABSTRACT FROM AUTHOR]

Objective: To compare changes in maxillary position assessed from a maxillary implant and three cephalometric methods based on linear measurements. Methods: Series of tracings of the maxilla obtained around puberty from an implant study were analyzed. The displacement of the implant was used to determine the direction and amount of "actual" maxillary growth. Displacement of point A was measured according to three cephalometric methods. The values obtained from absolute, horizontal, and vertical displacement of point A by three cephalometric methods and by the implant method were compared. Results: Results showed that estimation of displacement of the maxilla by three cephalometric methods (point A) was significantly larger than that of the implant method in all directions. The average difference in the horizontal plane was 0.7 mm, 1.2 mm, and 1.6 mm, respectively; the average difference in the vertical plane was 2.2 mm, 2.5 mm, and 3.6 mm, respectively. Conclusions: Estimations of changes in maxillary position by the implant method and by cephalometric methods were not proportional. All three cephalometric methods overestimated changes in the position of the maxilla. [ABSTRACT FROM AUTHOR]

Objective: To test the feasibility of automated lateral cephalometric radiograph (LCR) superimposition using an image fitting algorithm. Materials and Methods: Using radiopaque markers, we identified seven cephalometric landmarks on three dry skulls, took digital LCRs on each in several rotated positions, and used a custom software program (XRay3D) to automatically superimpose each rotated image on the initial image using an anterior cranial base reference. We measured superimposition error at each landmark and adjusted image brightness levels to simulate potential fitting error due to exposure variation. Results: The greatest mean error for 24 image rotation trials of less than 100 was less than 0.5 mm. Rotations of 100 or more were not reliably superimposed. Errors of 0.2-1.6 mm occurred for ±10% brightness but increased exponentially with further brightness alteration. Conclusion: Automated superimposition of LCRs, using this fitting technique, has great potential when rotation is less than 10° and brightness variation is less than 10%. [ABSTRACT FROM AUTHOR]

Objective. To observe the morphological relationship between the maxillofacial skeleton and medial pterygoid muscle by superimposing images constructed by MRI on a cephalogram. Design: Cross-sectional study. Setting: The Departments of Maxillofacial Orthognathics and Orthodontics, Tokyo Medical and Dental University. Participants: Sixteen patients (5 males and II females, aged between 13.5 and 27.5 years) with various craniofacial skeletal patterns, who were about to start orthodontic treatment. Methods: Lateral cephalometric radiographs and MRI scans were obtained and their images uploaded to a computer using a digitizer. The area of the medial pterygoid muscle was selected by binarization from the MRI. The mid-sagittal-plane MRI with a complete superimposed sagittal image of the medial pterygoid muscle was superimposed on the cephalogram using anatomical structures situated in the mid-sagittal plane of the head and shapes that could be identified from both the radiograph and the MRI image. Results: These combined images showed various shapes of the medial pterygoid muscle. The inclination axis of the medial pterygoid muscle was correlated with various cephalometric variables including SNB (r0.658), Facial angle (r0.601), ramus inclination (r=0.676) and Ba-Po% (r=0.585). The volume of the medial pterygoid muscle was also correlated with cephalometric variables such as ramus inclination (r=0.453), Ba-Nmm (r=0.676), Ba-Po% (depth) (r=0.447), Ar-Go% (depth) (r=0.444) and Ar-Go% (actual length) (r=0.532). Conclusions: Morphometric analysis using a superimposed image of the medial pterygoid muscle produced from a cephalogram and MRI may help explain the influence of the medial pterygoid muscle inclination axis and volume on the shape of the mandibular bone, especially the shape of the ramus. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Thermodynamics is the property of International Centre for Applied Thermodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To investigate the precise longitudinal change in the periodontal ligament (PDL) space width and three-dimensional tooth movement with continuous-force magnitudes in living rats. Materials and Methods: Using nickel-titanium closed-coil springs for 28 days, 10-, 25-, 50-, and 100-g mesial force was applied to the maxillary left first molars. Micro-CT was taken in the same rat at 0, 1, 2, 3, 10, 14, and 28 days. The width of the PDL was measured in the pressure and tension sides from 0 to 3 days. Angular and linear measurements were used to evaluate molar position at day 0, 10, 14, and 28. The finite element model (FEM) was constructed to evaluate the initial stress distribution, molar displacement, and center of rotation of the molar. Results: The initial evaluation of PDL width showed no statistical differences among different force magnitudes. Tooth movement was registered 1 hour after force application and gradually increased with time. From day 10, greater tooth movement was observed when 10 g of force was applied. The FEM showed that the center of rotation in the molar is located in the center of five roots at the apical third of the molar roots. Conclusion: The rat's molar movement mainly consists of mesial tipping, extrusion of distal roots, intrusion of mesial root, palatal inclination, and mesial rotation. Although the initial tooth movement after the application of different force magnitudes until day 3 was not remarkably different, 10 g of force produced more tooth movement compared with heavier forces at day 28. [ABSTRACT FROM AUTHOR]

Objective: To (1) evaluate the stability of palatal rugae as landmarks for superimposition of dental casts and (2) establish a three-dimensional superimposition method of maxillary dental casts for analyzing orthodontic tooth movement. Materials and Methods: The sample consisted of dental casts obtained from 10 patients treated with extraction of bilateral maxillary first premolars and placement of three palatal miniscrews as anchorage for retraction of the anterior teeth. Dental casts were measured by means of laser surface scanning system, and three-dimensional images were reconstructed. Serial dental casts were superimposed on the three miniscrews as registration landmarks (miniscrew-superimposition method), and the displacement of each palatal ruga point during the closure of extraction spaces was measured. Displacement of the central incisors was measured by the miniscrew-superimposition method and the proposed superimposition technique (ruga-palate-superimposition method). Correlation analysis and paired t-tests were performed to determine whether a significant difference existed between the measurements of the two superimposition methods. Results: The medial points of the third palatal rugae and the shape of the palatal vault were stable throughout the treatment. The displacement of the central incisors measured using the ruga-palate-superimposition method showed no significant difference with that measured using the miniscrew-superimposition method. Conclusion: The maxillary dental casts can be reliably superimposed on the medial points of the third palatal rugae arid the palatal vault as reference landmarks. [ABSTRACT FROM AUTHOR]

Objective: To compare traditional superimposition on sella turcica and the anterior cranial base (SACB) to superimposition referenced at the occipital condyle (I-point) for demonstrating craniofacial growth and development. Materials and methods: Tracings for ages 8, 10, 12, 15 and 18 were chosen from the Bolton Standards of Dentofacial Developmental Growth to compare superimposition with the traditional longitudinal reference at SACB (anterior curvature of sella turcica and anterior cranial base) to reference at I-point on the antero-inferior contour of the occipital condyles in norma lateralis. The serial tracings were superimposed using both the sagittal and postero-anterior (PA) tracings. Incremental growth of landmarks was measured in relation to Cartesian coordinates and compared between the superimposition methods. Results: Sagittal and PA tracing superimpositions displayed an average 7 mm greater cephalad movement of landmarks, an average 2.4 mm greater ventral movement, and comparable transverse dimension with superimposition referenced at 1-point as compared to the SACB reference. Conclusion: I-point superimposition demonstrates physiologic growth patterns concealed by traditional registration at sella turcica. The evolution of superimposition on SACB was based on convenience and reproducibility. Fundamental principles of bone development are consistent with the occipital condyles as a more biologic reference for relative craniofacial growth. Actual vertical growth is believed to be greater than displayed in this study, due to the cross-sectional and blended nature of the sample. [ABSTRACT FROM AUTHOR]

Objective: To test the hypothesis that there is no difference between the information produced by superimposition of serial lateral headfilms on anatomical structures and that produced by superimposition on metallic implants according to the protocols of Björk. Materials and Methods: Serial cephalograms of 10 untreated subjects who had tantalum implants placed in the maxilla and mandible during childhood were analyzed. Headfilms taken at six consecutive stages of cervical vertebral maturation (CS1-CS6) for six female and four male subjects were used. Tracings were superimposed according to the methods of superimpositions advocated by the American Board of Orthodontics (ABO). In addition, superimpositions along the inferior border of the mandible were performed. Finally, superimpositions of serial tracings on stable intraosseous implants were made to determine the actual growth and remodeling patterns of the maxilla and mandible. Results: The ABO maxillary superimposition method underestimates the vertical displacement and overestimates the forward movement of maxillary landmarks. Superimposing on the internal cortical outline of the symphysis and the inferior alveolar nerve canals generally approximates the mandibular superimposition on implants, although the lower anterior border of the symphysis may be a preferable area of superimposition. Superimposition on the lower border of the mandible does not reflect accurately the actual pattern of growth and remodeling of the mandible. Conclusions: When analyzing serial headfilms, erroneous information concerning patterns of bone growth and remodeling can be obtained if convenient, but biologically incorrect superimposition protocols are used. In addition, tooth movements measured can be distorted significantly depending on the method of superimposition. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the influence of attachments and interproximal reduction on canines undergoing rotational movement with Invisalign. Materials and Methods: In this prospective clinical study, 53 canines (33 maxillary and 20 mandibular) were measured from the virtual TREAT models of 31 participants treated with anterior Invisalign. The pretreatment virtual model of the predicted final tooth position was superimposed on the posttreatment virtual model using ToothMeasure, Invisalign's proprietary measurement software. A one-way analysis of variance (ANOVA) (P < .05) compared three treatment modalities: attachments only (AO), interproximal reduction only (IO), and neither attachments nor interproximal reduction (N). Student's t-tests (P < .05) compared the mean accuracy of canine rotation between arches. Results: The mean accuracy of canine rotation with Invisalign was 35.8% (SD = 26.3). Statistical analyses indicated that there was no significant difference in accuracy between groups AO, IO, and N (P = .343). There was no statistically significant difference (P = .888) in rotational accuracy for maxillary and mandibular canines for any of the treatment groups. The most commonly prescribed attachment shape was the vertical-ellipsoid (70.5%). Conclusions: Vertical-ellipsoid attachments and interproximal reduction do not significantly improve the accuracy of canine rotation with the Invisalign system. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this investigation was to assess the feasibility of building a virtual human face digitally by superimposing a photo-realistic three-dimensional (3D) soft-tissue surface on bone in the correct relationship and evaluating the registration errors associated with this method. The 3D soft-tissue surface of the face was captured using a fast stereophotogrammetry method and the underlying bone was recorded using a 3D computed tomography (CT) scanner. Using the Procrustes registration method, the outer surface of the 3D CT scan and the photo-realistic soft-tissue surfaces were merged into a single Virtual Reality Modelling Language (VRML) file and displayed using a standard VRML viewer. Quantitative measurements of registration errors were calculated in the reconstructed human head models using the signed closest point distance from the photo-realistic skin surface to the transformed CT skin surface. The registration errors between most parts of the aligned surfaces were within ±1.5mm. The errors were relatively large around the eyebrows, eyelids and cheeks. Simultaneous recording of the face and skull may reduce this error. [Copyright &y& Elsevier]