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A novel shape representation of the dental arch and its applications in some dentistry problems

Rijal OM, Abdullah NA, Isa ZM, Davaei FA, Noor NM, Tawfiq OF

Annu Int Conf IEEE Eng Med Biol Soc, 2011;2011:5092-5.
PMID: 22255484 DOI: 10.1109/IEMBS.2011.6091261

Standardized digital images of maxillary dental casts of 47 subjects were analyzed using MATLAB software whereby the two hamular notches and the incisive papilla defines the Cartesian vertical and horizontal axes, as well as the origin. The angle and length of the midpoints of the anterior teeth, mesiobuccal and distobuccal cusp of the posterior teeth were measured from the origin and denoted as θ(1), …, θ(18) and l(1), …, l(18) respectively. These values were collectively used to represent the shape of each dental cast. Clustering and principal component analyses were employed to find possible groups of dental arches using the above measure of shape. The main result of this study is that the 3 groups of dental arch shape may be represented by the novel feature vector v(k) = (θ(k)(1), l(k)(1), θ(k)(3), l(k)(3), θ(k)(5), l(k)(5), θ(k)(13), l(k)(13)), k = 1, 2, 3. Knowledge of v(k) implies three impression trays should be sufficient in a particular prosthetic dentistry application for Malaysian patients. Further, given that v(k) are accurately measured they may be potential candidates as evidence in specific application of forensic dentistry.

Matched MeSH terms: Imaging, Three-Dimensional/methods*
Body surface area measurement and soft clustering for PASI area assessment

Hani AF, Prakasa E, Nugroho H, Affandi AM, Hussein SH

Annu Int Conf IEEE Eng Med Biol Soc, 2012;2012:4398-401.
PMID: 23366902 DOI: 10.1109/EMBC.2012.6346941

Psoriasis is a common skin disorder with a prevalence of 0.6 - 4.8% around the world. The most common is plaques psoriasis and it appears as red scaling plaques. Psoriasis is incurable but treatable in a long term treatment. Although PASI (Psoriasis Area and Severity Index) scoring is recognised as gold standard for psoriasis assessment, this method is still influenced by inter and intra-rater variation. An imaging and analysis system called α-PASI is developed to perform PASI scoring objectively. Percentage of lesion area to the body surface area is one of PASI parameter. In this paper, enhanced imaging methods are developed to improve the determination of body surface area (BSA) and lesion area. BSA determination method has been validated on medical mannequin. BSA accuracies obtained at four body regions are 97.80% (lower limb), 92.41% (trunk), 87.72% (upper limb), and 83.82% (head). By applying fuzzy c-means clustering algorithm, the membership functions of lesions area for PASI area scoring have been determined. Performance of scoring result has been tested with double assessment by α-PASI area algorithm on body region images from 46 patients. Kappa coefficients for α-PASI system are greater than or equal to 0.72 for all body regions (Head - 0.76, Upper limb - 0.81, Trunk - 0.85, Lower limb - 0.72). The overall kappa coefficient for the α-PASI area is 0.80 that can be categorised as substantial agreement. This shows that the α-PASI area system has a high reliability and can be used in psoriasis area assessment.

Matched MeSH terms: Imaging, Three-Dimensional/methods
Alpha shape theory for 3D visualization and volumetric measurement of brain tumor progression using magnetic resonance images

Hamoud Al-Tamimi MS, Sulong G, Shuaib IL

Magn Reson Imaging, 2015 Jul;33(6):787-803.
PMID: 25865822 DOI: 10.1016/j.mri.2015.03.008

Resection of brain tumors is a tricky task in surgery due to its direct influence on the patients' survival rate. Determining the tumor resection extent for its complete information via-à-vis volume and dimensions in pre- and post-operative Magnetic Resonance Images (MRI) requires accurate estimation and comparison. The active contour segmentation technique is used to segment brain tumors on pre-operative MR images using self-developed software. Tumor volume is acquired from its contours via alpha shape theory. The graphical user interface is developed for rendering, visualizing and estimating the volume of a brain tumor. Internet Brain Segmentation Repository dataset (IBSR) is employed to analyze and determine the repeatability and reproducibility of tumor volume. Accuracy of the method is validated by comparing the estimated volume using the proposed method with that of gold-standard. Segmentation by active contour technique is found to be capable of detecting the brain tumor boundaries. Furthermore, the volume description and visualization enable an interactive examination of tumor tissue and its surrounding. Admirable features of our results demonstrate that alpha shape theory in comparison to other existing standard methods is superior for precise volumetric measurement of tumor.

Matched MeSH terms: Imaging, Three-Dimensional/methods*
Three-dimensional image analysis of developing mandibular third molars apices for age estimation: A study using CBCT data enhanced with Mimics & 3-Matics software

Asif MK, Nambiar P, Ibrahim N, Al-Amery SM, Khan IM

Leg Med (Tokyo), 2019 Jul;39:9-14.
PMID: 31158731 DOI: 10.1016/j.legalmed.2019.05.003

Three-dimensional imaging has improved the method of analysis in many forensic science investigations. The study aimed to derive regression equation for age estimation by investigating the relationship between chronological age and surface area of the developing mandibular 3rd molars apices. Furthermore, other predictor variables: ethnicity (Malay and Chinese), gender and status of the root development completion (open/closed apices) were also investigated in terms of fit to the age estimation model. One hundred and twenty eight training and 55 validation samples of intact mandibular 3rd molars were selected from 183 CBCT scans. The samples comprised of 93 Malays and 90 Chinese, ranging in age from 13 to 24 years. Three-dimensional image modeling and surface area analysis of the developing mandibular 3rd molars apices were performed using Mimics and 3-Matics software. Multiple linear regression analysis was used to derive age estimation model using chronological age as a dependent variable and surface area of the apices, ethnicity, gender and status of the root development completion (open/closed apices) as predictor variables. A strong inverse correlation (r = 0.95, SD = 1.144) was observed between chronological age and all the predictor variables. The results showed that 89.6% of the variation in age can be explained by the predictor variables. Mean absolute error (MAE) value of 0.8223 was observed when the derived regression equation was tested on the independent validation sample. In conclusion, three-dimensional surface area analysis of the developing mandibular 3rd molars apices can be used as a reliable method for age estimation.

Matched MeSH terms: Imaging, Three-Dimensional*
Three-Dimensional Computed Tomography Analysis of the Posterior Tibial Slope in 100 Knees

Ho JPY, Merican AM, Hashim MS, Abbas AA, Chan CK, Mohamad JA

J Arthroplasty, 2017 10;32(10):3176-3183.
PMID: 28579444 DOI: 10.1016/j.arth.2017.04.060

BACKGROUND: The posterior tibial slope (PTS) is an important consideration in knee arthroplasty. However, there is still no consensus for the optimal slope. The objectives of this study were (1) to reliably determine the native PTS in this population using 3-dimensional computed tomography scans and (2) to determine the normal reference range for PTS in this population.
METHODS: One hundred computed tomography scans of disease-free knees were analyzed. A 3-dimensional reconstructed image of the tibia was generated and aligned to its anatomic axis in the coronal and sagittal planes. The tibia was then rotationally aligned to the tibial plateau (tibial centroid axis) and PTS was measured from best-fit planes on the surface of the proximal tibia and individually for the medial and lateral plateaus. This was then repeated with the tibia rotationally aligned to the ankle (transmalleolar axis).
RESULTS: When rotationally aligned to the tibial plateau, the mean PTS, medial PTS, and lateral PTS were 11.2° ± 3.0 (range, 4.7°-17.7°), 11.3° ± 3.2 (range, 2.7°-19.7°), and 10.9° ± 3.7 (range, 3.5°-19.4°), respectively. When rotationally aligned to the ankle, the mean PTS, medial PTS, and lateral PTS were 11.4° ± 3.0 (range, 5.3°-19.3°), 13.9° ± 3.7 (range, 3.1°-24.4°), and 9.7° ± 3.6 (range, 0.8°-17.7°), respectively.
CONCLUSION: The PTS in the normal Asian knee is on average 11° (mean) with a reference range of 5°-17° (mean ± 2 standard deviation). This has implications to surgery and implant design.

Matched MeSH terms: Imaging, Three-Dimensional/methods
Assessing regional left ventricular thickening dysfunction and dyssynchrony via personalized modeling and 3D wall thickness measurements for acute myocardial infarction

Khalid A, Lim E, Chan BT, Abdul Aziz YF, Chee KH, Yap HJ, et al.

J Magn Reson Imaging, 2019 04;49(4):1006-1019.
PMID: 30211445 DOI: 10.1002/jmri.26302

BACKGROUND: Existing clinical diagnostic and assessment methods could be improved to facilitate early detection and treatment of cardiac dysfunction associated with acute myocardial infarction (AMI) to reduce morbidity and mortality.
PURPOSE: To develop 3D personalized left ventricular (LV) models and thickening assessment framework for assessing regional wall thickening dysfunction and dyssynchrony in AMI patients.
STUDY TYPE: Retrospective study, diagnostic accuracy.
SUBJECTS: Forty-four subjects consisting of 15 healthy subjects and 29 AMI patients.
FIELD STRENGTH/SEQUENCE: 1.5T/steady-state free precession cine MRI scans; LGE MRI scans.
ASSESSMENT: Quantitative thickening measurements across all cardiac phases were correlated and validated against clinical evaluation of infarct transmurality by an experienced cardiac radiologist based on the American Heart Association (AHA) 17-segment model.
STATISTICAL TEST: Nonparametric 2-k related sample-based Kruskal-Wallis test; Mann-Whitney U-test; Pearson's correlation coefficient.
RESULTS: Healthy LV wall segments undergo significant wall thickening (P 50% transmurality) underwent remarkable wall thinning during contraction (thickening index [TI] = 1.46 ± 0.26 mm) as opposed to healthy myocardium (TI = 4.01 ± 1.04 mm). For AMI patients, LV that showed signs of thinning were found to be associated with a significantly higher percentage of dyssynchrony as compared with healthy subjects (dyssynchrony index [DI] = 15.0 ± 5.0% vs. 7.5 ± 2.0%, P

Matched MeSH terms: Imaging, Three-Dimensional*
Fulltext A three-dimensional collagen construct to model lipopolysaccharide-induced activation of BV2 microglia

Haw RT, Tong CK, Yew A, Lee HC, Phillips JB, Vidyadaran S

J Neuroinflammation, 2014 Jul 30;11:134.
PMID: 25074682 DOI: 10.1186/1742-2094-11-134

BACKGROUND: We report a novel method of culturing microglia in three dimension (3D) using collagen as a substrate. By culturing microglia within a matrix, we aim to emulate the physical state of microglia embedded within parenchyma.
METHODS: BV2 microglia cell suspensions were prepared with type I collagen and cast into culture plates. To characterise the BV2 microglia cultured in 3D, the cultures were evaluated for their viability, cell morphology and response to lipopolysaccharide (LPS) activation. Conventional monolayer cultures (grown on uncoated and collagen-coated polystyrene) were set up concurrently for comparison.
RESULTS: BV2 microglia in 3D collagen matrices were viable at 48 hrs of culture and exhibit a ramified morphology with multiplanar cytoplasmic projections. Following stimulation with 1 μg/ml LPS, microglia cultured in 3D collagen gels increase their expression of nitric oxide (NO) and CD40, indicating their capacity to become activated within the matrix. Up to 97.8% of BV2 microglia grown in 3D cultures gained CD40 positivity in response to LPS, compared to approximately 60% of cells grown in a monolayer (P

Matched MeSH terms: Imaging, Three-Dimensional*
Three-dimensional quantitative evaluation of facial morphology in adults with unilateral cleft lip and palate, and patients without clefts

Othman SA, Ahmad R, Asi SM, Ismail NH, Rahman ZA

Br J Oral Maxillofac Surg, 2014 Mar;52(3):208-13.
PMID: 24342372 DOI: 10.1016/j.bjoms.2013.11.008

The aims of this study were to assess the quantitative values of measurements using proportion indices in the craniofacial region in patients with repaired, non-syndromic, complete unilateral cleft lip and palate (UCLP), and compare them with a control group who did not have clefts using the non-invasive systems of 3-dimensional technology. Three-dimensional measurements of the facial surfaces of 15 Malay patients who had UCLP repaired and 100 Malay control patients aged 18-25 years were analysed. The 3-dimensional images of the respondents' faces were captured using the VECTRA-3D Stereophotogrammetry System. Eleven craniofacial proportions were assessed using a combination of 18 linear measurements obtained from 21 anthropometric soft tissue landmarks. These measurements were used to produce proportion indices to find the differences in the morphological features between the groups, and assessed using the independent sample t test and z scores. There were significant differences between the groups in 7 out of 11 craniofacial proportion indices (p=0.001-0.044). Z scores of 2 indices were disproportionate. They were nasal index (which was severely supernormal) and upper lip index (which was moderately supernormal). Patients with UCLP had higher mean z scores, indicating that patients with UCLP tended to have larger faces than the control group. There were clinically important differences mainly in the nasolabial area, where the nose and the upper lip were wider, larger, or flatter in patients with UCLP.

Matched MeSH terms: Imaging, Three-Dimensional/methods*
Fulltext Design process of cementless femoral stem using a nonlinear three dimensional finite element analysis

Baharuddin MY, Salleh ShH, Zulkifly AH, Lee MH, Noor AM, A Harris AR, et al.

BMC Musculoskelet Disord, 2014;15:30.
PMID: 24484753 DOI: 10.1186/1471-2474-15-30

Minimal available information concerning hip morphology is the motivation for several researchers to study the difference between Asian and Western populations. Current use of a universal hip stem of variable size is not the best option for all femur types. This present study proposed a new design process of the cementless femoral stem using a three dimensional model which provided more information and accurate analysis compared to conventional methods.

Matched MeSH terms: Imaging, Three-Dimensional*
Tooth size and dental arch dimensions: a stereophotogrammetric study in Southeast Asian Malays

Al-Khatib AR, Rajion ZA, Masudi SM, Hassan R, Anderson PJ, Townsend GC

Orthod Craniofac Res, 2011 Nov;14(4):243-53.
PMID: 22008304 DOI: 10.1111/j.1601-6343.2011.01529.x

To investigate tooth size and dental arch dimensions in Malays using a stereophotogrammetric system.

Matched MeSH terms: Imaging, Three-Dimensional/methods
Assessment of 3-D nasal airway morphology in Southeast Asian adults with obstructive sleep apnea using acoustic rhinometry

Banabilh SM, Suzina AH, Mohamad H, Dinsuhaimi S, Samsudin AR, Singh GD

Clin Oral Investig, 2010 Oct;14(5):491-8.
PMID: 19806371 DOI: 10.1007/s00784-009-0342-9

The aim of the present study is to investigate nasal airway morphology in Asian adults with and without obstructive sleep apnea (OSA) using acoustic rhinometry (AR), principal components analysis (PCA), and 3-D finite-element analysis (FEA). One hundred eight adult Malays aged 18-65 years (mean ± SD, 33.2 ± 13.31) underwent clinical examination and limited channel polysomnography, providing 54 patients with OSA and 54 non-OSA controls. The mean minimal cross section area 1 (MCA1) and the mean minimal cross sectional area 2 (MCA2) were obtained from AR for all subjects and subjected to t tests. The OSA and control nasal airways were reconstructed in 3-D and subjected to PCA and FEA. The mean MCA1 and MCA2 using AR were found to be significantly smaller in the OSA group than in the control group (p < 0.001). Comparing the 3-D OSA and control nasal airways using PCA, the first two eigenvalues accounted for 94% of the total shape change, and statistical differences were found (p < 0.05). Similarly, comparing the nasal airways using FEA, the 3-D mean OSA nasal airway was significantly narrower in the OSA group compared to the control group. Specifically, decreases in size of approx. 10-22% were found in the nasal valve/head of inferior turbinate area. In conclusion, differences in nasal airway morphology are present when comparing patients with OSA to controls. These differences need to be recognized as they can improve our understanding of the etiological basis of obstructive sleep apnea and facilitate its subsequent management.

Matched MeSH terms: Imaging, Three-Dimensional/methods*
Brain white and gray matter anatomy of MRI segmentation based on tissue evaluation

Salih QA, Ramli AR, Mahmud R, Wirza R

MedGenMed, 2005;7(2):1.
PMID: 16369380

Different approaches to gray and white matter measurements in magnetic resonance imaging (MRI) have been studied. For clinical use, the estimated values must be reliable and accurate when, unfortunately, many techniques fail on these criteria in an unrestricted clinical environment. A recent method for tissue clusterization in MRI analysis has the advantage of great simplicity, and it takes the account of partial volume effects. In this study, we will evaluate the intensity of MR sequences known as T1-weighted images in an axial sliced section. Intensity group clustering algorithms are proposed to achieve further diagnosis for brain MRI, which has been hardly studied. Subjective study has been suggested to evaluate the clustering group intensity in order to obtain the best diagnosis as well as better detection for the suspected cases. This technique makes use of image tissue biases of intensity value pixels to provide 2 regions of interest as techniques. Moreover, the original mathematic solution could still be used with a specific set of modern sequences. There are many advantages to generalize the solution, which give far more scope for application and greater accuracy.

Matched MeSH terms: Imaging, Three-Dimensional/methods
Diagnostic ability of computed tomography using DentaScan software in endodontics: case reports

Siotia J, Gupta SK, Acharya SR, Saraswathi V

Int J Comput Dent, 2011;14(4):321-34.
PMID: 22324223

Radiographic examination is essential in diagnosis and treatment planning in endodontics. Conventional radiographs depict structures in two dimensions only. The ability to assess the area of interest in three dimensions is advantageous. Computed tomography is an imaging technique which produces three-dimensional images of an object by taking a series of two-dimensional sectional X-ray images. DentaScan is a computed tomography software program that allows the mandible and maxilla to be imaged in three planes: axial, panoramic, and cross-sectional. As computed tomography is used in endodontics, DentaScan can play a wider role in endodontic diagnosis. It provides valuable information in the assessment of the morphology of the root canal, diagnosis of root fractures, internal and external resorptions, pre-operative assessment of anatomic structures etc. The aim of this article is to explore the clinical usefulness of computed tomography and DentaScan in endodontic diagnosis, through a series of four cases of different endodontic problems.

Matched MeSH terms: Imaging, Three-Dimensional/methods*
Is C1 lateral mass screw placement safe for the Chinese, Indians, and Malays? An analysis of 180 computed tomography scans

Lee CK, Tan TS, Chan C, Kwan MK

J Orthop Surg (Hong Kong), 2017 01;25(1):2309499017692683.
PMID: 28211302 DOI: 10.1177/2309499017692683

INTRODUCTION: C1 lateral mass (C1LM) screw is a common procedure in spine surgery. However, related studies are lacking in Asia. We aim to determine the safety of C1LM screw for the Chinese, Indians, and Malays.
METHODS: Three-dimensional computed tomographies of 180 subjects (60 from each ethnic) were analyzed. The length and angulations of C1LM screw and the location of internal carotid artery (ICA) in relation to C1LM were assessed and classified according to the classification by Murakami et al. The incidence of ponticulus posticus (PP) was determined and the differences among the population of these three ethnics were recorded.
RESULTS: The average base length was 8.5 ± 1.4 mm. The lengths within the lateral mass were between 14.7 ± 1.6 mm and 21.7 ± 2.3 mm. The prevalence of PP was 8.3%. 55.3% (199) of ICA were located in zone 0, 38.3% (138) in zone 1-1, 6.4% (23) in zone 1-2, and none in zone 1-3 and zone 2. The average angulation from the entry point to the ICA was 8.5° ± 6.4° laterally. The mean distance of ICA from C1 anterior cortex was 3.7 ± 1.7 mm (range: 0.6∼11.3). There was no difference in distribution of ICA in zone 1 among the three population (Chinese-47%, Indians-61%, and Malays-53%; p > 0.05).
CONCLUSIONS: No ICA is located medial to the entry point of C1LM screw. If bicortical purchase of C1LM screw is needed, screw protrusion of less than 3 mm or medially angulated is safe for ICA. The incidence of PP is 8.3% with higher prevalence among the Indian population.

Matched MeSH terms: Imaging, Three-Dimensional*
Three dimensional neuro-retinal rim thickness and retinal nerve fiber layer thickness using high-definition optical coherence tomography for open-angle glaucoma

Subramaniam S, Jeoung JW, Lee WJ, Kim YK, Park KH

Jpn. J. Ophthalmol., 2018 Nov;62(6):634-642.
PMID: 30229404 DOI: 10.1007/s10384-018-0620-7

PURPOSE: To compare the diagnostic capability of three-dimensional (3D) neuro-retinal rim thickness (NRR) with existing optic nerve head and retinal nerve fiber layer (RNFL) scan parameters using high-definition optical coherence tomography (HD-OCT).
DESIGN: Retrospective study.
METHODS: Based on the mean deviation (MD) of the Humphrey Field Analyzer (HFA), the 152 subjects were categorized into mild (MD > - 6 dB, 100), moderate (MD - 6 to - 12 dB, 26), and severe (MD

Matched MeSH terms: Imaging, Three-Dimensional*
The prevalence of abnormal posterior compartment anatomy and its association with obstructed defecation symptoms in urogynecological patients

Guzman Rojas R, Kamisan Atan I, Shek KL, Dietz HP

Int Urogynecol J, 2016 Jun;27(6):939-44.
PMID: 26670577 DOI: 10.1007/s00192-015-2914-3

INTRODUCTION AND HYPOTHESIS: Symptoms of obstructive defecation (OD) are common in women. Transperineal ultrasound (TPUS) has been used for the evaluation of defecatory disorders. The aim of our study was to determine the overall prevalence of anatomical abnormalities of the posterior compartment and their correlations with OD in women seen in a tertiary urogynecology clinic.
METHODS: This is a retrospective study on 750 women seen at a tertiary urogynecological unit who had undergone a standardized interview, clinical examination, and 4D TPUS. Univariate and multivariate logistic regression analyses were undertaken to study the association between examination findings and symptoms of OD. This study was approved by the local human research ethics committee (Nepean Blue Mountains Local Health District Human Research Ethics Committee, IRB approval no. 13-16).
RESULTS: The datasets of 719 women were analyzed. Mean age was 56.1 (18.4-87.6) years. Ninety-seven patients (13 %) reported fecal incontinence, 190 (26 %) constipation, and 461 (64 %) symptoms of OD. On examination, 405 women (56 %) were diagnosed with significant posterior compartment prolapse (POP-Q ≥ stage 2), which was associated with symptoms of OD (p

Matched MeSH terms: Imaging, Three-Dimensional
Fulltext Virtual reality based support system for layout planning and programming of an industrial robotic work cell

Yap HJ, Taha Z, Dawal SZ, Chang SW

PLoS One, 2014;9(10):e109692.
PMID: 25360663 DOI: 10.1371/journal.pone.0109692

Traditional robotic work cell design and programming are considered inefficient and outdated in current industrial and market demands. In this research, virtual reality (VR) technology is used to improve human-robot interface, whereby complicated commands or programming knowledge is not required. The proposed solution, known as VR-based Programming of a Robotic Work Cell (VR-Rocell), consists of two sub-programmes, which are VR-Robotic Work Cell Layout (VR-RoWL) and VR-based Robot Teaching System (VR-RoT). VR-RoWL is developed to assign the layout design for an industrial robotic work cell, whereby VR-RoT is developed to overcome safety issues and lack of trained personnel in robot programming. Simple and user-friendly interfaces are designed for inexperienced users to generate robot commands without damaging the robot or interrupting the production line. The user is able to attempt numerous times to attain an optimum solution. A case study is conducted in the Robotics Laboratory to assemble an electronics casing and it is found that the output models are compatible with commercial software without loss of information. Furthermore, the generated KUKA commands are workable when loaded into a commercial simulator. The operation of the actual robotic work cell shows that the errors may be due to the dynamics of the KUKA robot rather than the accuracy of the generated programme. Therefore, it is concluded that the virtual reality based solution approach can be implemented in an industrial robotic work cell.

Matched MeSH terms: Imaging, Three-Dimensional
Dento-facial relationships in individuals with normal occlusion

Al-Khatib AR, Rajion ZA, Masudi SM, Hassan R, Townsend GC

Homo, 2013 Aug;64(4):296-311.
PMID: 23755965 DOI: 10.1016/j.jchb.2013.04.002

The aim of this study was to evaluate the relationships of selected facial measurements with mesio-distal crown widths and dental arch dimensions in individuals with normal occlusions. A cross-sectional study was conducted on 276 subjects with Angle's Class I normal occlusions. Three-dimensional images of the face and dental casts were captured and analyzed using stereophotogrammetric systems. Significant correlations were found between the sagittal facial variables and both upper and lower dental arch dimensions and to lesser degree with the horizontal and vertical variables. The values of correlation coefficients calculated between facial and dental crown measurements ranged from .01 to .50 for upper teeth and .01 to .49 for lower teeth. The values of correlation coefficients between facial and upper dental arch dimensions ranged from .01 to .55 and those between facial and lower dental arch dimensions ranged from .01 to .60. A principal components analysis showed that the sagittal dimensions, face height, nose, labial fissure, binocular widths were positively associated with dental arch dimensions and mesio-distal crown diameters in males. On the other hand, only the sagittal variables were associated with dental dimensions in females. The results of this study confirm that positive associations exist between facial and dental arch dimensions. These relationships should be taken into consideration when attempts are made to modify dental arch size as part of orthodontic treatment. Moreover, these relationships are also relevant to prosthodontists involved with selecting tooth sizes that display optimal functional balance with the craniofacial structures.

Matched MeSH terms: Imaging, Three-Dimensional
Comparative analysis of realistic CT-scan and simplified human airway models in airflow simulation

Johari NH, Osman K, Helmi NH, Abdul Kadir MA

Comput Methods Biomech Biomed Engin, 2015;18(1):48-56.
PMID: 23521065 DOI: 10.1080/10255842.2013.776548

Efforts to model the human upper respiratory system have undergone many phases. Geometrical proximity to the realistic shape has been the subject of many research projects. In this study, three different geometries of the trachea and main bronchus were modelled, which were reconstructed from computed tomography (CT) scan images. The geometrical variations were named realistic, simplified and oversimplified. Realistic refers to the lifelike image taken from digital imaging and communications in medicine format CT scan images, simplified refers to the reconstructed image based on natural images without realistic details pertaining to the rough surfaces, and oversimplified describes the straight wall geometry of the airway. The characteristics of steady state flows with different flow rates were investigated, simulating three varied physical activities and passing through each model. The results agree with previous studies where simplified models are sufficient for providing comparable results for airflow in human airways. This work further suggests that, under most exercise conditions, the idealised oversimplified model is not favourable for simulating either airflow regimes or airflow with particle depositions. However, in terms of immediate analysis for the prediction of abnormalities of various dimensions of human airways, the oversimplified techniques may be used.

Matched MeSH terms: Imaging, Three-Dimensional
A radiological evaluation of the morphometry and safety of S1, S2 and S2-ilium screws in the Asian population using three dimensional computed tomography scan: an analysis of 180 pelvis

Kwan MK, Jeffry A, Chan CY, Saw LB

Surg Radiol Anat, 2012 Apr;34(3):217-27.
PMID: 22194086 DOI: 10.1007/s00276-011-0919-2

Studies of sacral pedicle anatomy have been reported in the European population. However, the feasibility for the use of S1, S2 and S2-ilium screws has not been fully investigated in the Asian population.

Matched MeSH terms: Imaging, Three-Dimensional

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