Evaluation of the biomechanics of Aramany class I obturators of different designs using numerical and experimental methods. Part II: Stress distribution.

STATEMENT OF PROBLEM: Evidence regarding stress evaluations of removable obturators with Aramany class I defects is lacking. Whether the stress distribution on Aramany class I prostheses can be improved by modifying the currently used designs is also unclear. PURPOSE: The purpose of part II of this study was to evaluate the stress distribution in different designs of Aramany class I obturators using finite element analysis (FEA) and photoelastic stress analysis. MATERIAL AND METHODS: Four finite element and 8 photoelastic models, including 2 acrylic resin base obturators retained with 2 Adams clasps, 2 linear, 2 tripodal, and 2 fully tripodal design obturators, were used in this study. The frameworks were fabricated on the casts obtained from a modified printed model. Vertical and oblique loads were applied on 2 points (anterior and posterior) of the models. The quantitative measurement was done by measuring the fringe orders and von Mises values to compare the influences of occlusal forces on the obturator components and their supporting structures. The qualitative evaluation was done by visual color mapping to identify the stress concentration. RESULTS: In the photoelastic analysis, the anterior abutments of the tripodal showed the highest stress, followed by the fully tripodal obturators, while, in FEA, the anterior abutments of the linear design received the most in both vertical and oblique load. The central incisor received the most stress in photoelastic (3 or more fringe orders) and FEA (687.3 and 150.1 MPa for vertical and oblique loads, respectively), followed by the lateral incisors. Upon posterior loading, the base of the defect of the linear design demonstrated the most stress in photoelastic (3 or more fringes) and FEA (94.3 and 130.5 MPa for vertical and oblique loads, respectively). The acrylic resin base obturator retained with Adams clasps demonstrated the lowest stress distribution in abutments and their supporting bone upon anterior and posterior loads. CONCLUSIONS: Upon vertical and oblique load application, the fully tripodal design was comparable with the tripodal in terms of stress distribution. Both designs were better than the linear in response to the same loading. The stress was concentrated at the anterior palatal part of the obturator, the base of the defect, and the junction of the metal and acrylic resin part of the prostheses upon anterior and posterior loading, respectively.

Evaluation of the biomechanics of Aramany class I obturators of different designs using numerical and experimental methods. Part I: Retention and associated stress.

STATEMENT OF PROBLEM: Studies on the biomechanics of obturators in the currently used designs of Aramany class I defect are lacking. Also, modifications of the designs presently used in unilateral palatal defects are needed to produce a prosthesis with more retention and less stress on the abutments. PURPOSE: The purpose of part I of this study was to differentiate among Aramany class I obturators of 4 designs regarding retention and associated stress using numerical and experimental methods. MATERIAL AND METHODS: Four finite element models and 36 different base obturators were fabricated and divided into 9 acrylic resin bases retained with Adams clasps and 9 linear, 9 tripodal, and 9 fully tripodal design obturators from casts obtained from a scanned skull. After modification, the prostheses were fabricated on the casts obtained from a 3-dimensionally printed cast. The retention was evaluated, and the data were collected and analyzed using a statistical software program (α=.05). The displacement and associated stress in the assorted casts were compared by using 5-N displacing force at 3 points using finite element analysis. The quantitative assessment was made by measuring the displacement and von Mises stress distribution on the prostheses and their supporting structures. The qualitative analysis was done by using a visual color mapping to depict stress location and intensity. RESULTS: No significant differences were found between fully tripodal (4.478 ±2.303 MPa) and tripodal obturators (4.478 ±2.286 MPa; P=.153), although fully tripodal showed more resistance to anterior displacement (4.522 ±0.979 and 3.553 ±1.58 MPa for fully tripodal and tripodal designs, respectively; P=.007), and tripodal obturators produced more resistance to middle displacement (5.441 ±1.778 and 2.784 ±0.432 MPa for tripodal and fully tripodal design respectively; P=.001). The fully tripodal obturator showed more retention (3.736 ±1.182 MPa) than the linear one (2.493 ±1.052 MPa; P=.001). The maxillary central incisor was the most stressed abutment, followed by the lateral incisor, while the second molar was the least. CONCLUSIONS: Regarding retention, the fully tripodal obturator produces retention comparable with the tripodal and significantly more than the linear. Acrylic resin prostheses retained with Adams clasps may be similar to metal-based prostheses regarding retention and stress distribution on the supporting structures.

Digital comparative analysis in three dimensions of two impression techniques for the bilateral distal extension of partially edentulous mandibular arches: A pilot clinical study.

STATEMENT OF PROBLEM: The stability of mandibular removable partial dentures with bilateral distal extensions may be improved with the controlled tissue support achieved by using the altered cast impression technique, although this process is time-consuming and technique-sensitive. PURPOSE: The purpose of this pilot clinical study was to compare casts generated from a conventional definitive impression with casts generated from an altered cast impression using a 3-dimensional (3D) analysis software program. MATERIAL AND METHODS: Three partially edentulous participants with mandibular Kennedy Class I were enrolled, and impressions were made with the 2 techniques and poured in stone. The casts were scanned, aligned, and superimposed by using a 3D analysis software program. Surface deviations were measured to evaluate the differences in displacement induced by the impression on the tissue surface. Five observations were made in 4 different areas on each partially edentulous side. Means from these observations were generated, and the Wilcoxon and Mann Whitney tests were performed for all data to assess the differences between the right and left sides in the same participant and among the 3 participants (α=.05). RESULTS: The casts made from the altered cast impression had an overall mean ±standard deviation displacement of -0.05 ±1.25 mm on the right and left sides of the mandibular buccal shelf area. Moreover, the greatest overall difference of about 0.45 ±0.41 mm occurred on the lingual slope of the residual ridge, and the differences in the other areas were 0.10 ±0.99 mm (crest of the residual ridge) and 0.16 ±0.66 mm (buccal slope of the residual ridge). The overall differences varied statistically between significance and nonsignificance for the same participant and among the 3 participants. CONCLUSIONS: A digital comparative analysis of the conventional and altered cast methods of recording the bilateral distal extension areas in partially edentulous participants showed that the altered cast method exhibited more displacement on the buccal vestibule or buccal shelf area compared with other examined areas. The differences between the 2 impression methods in the displacement values among the examined areas were minimal and in close proximity, and such differences may lack clinical significance.

Correction: Evaluation of the osteogenic potential of demineralized and decellularized bovine bone granules following implantation in rat calvaria critical-size defect model.

[This corrects the article DOI: 10.1371/journal.pone.0294291.].

Development of Artificial Neural Network-Based Prediction Model for Evaluation of Maxillary Arch Growth in Children with Complete Unilateral Cleft Lip and Palate.

INTRODUCTION: Cleft lip and palate (CLP) are the most common congenital craniofacial deformities that can cause a variety of dental abnormalities in children. The purpose of this study was to predict the maxillary arch growth and to develop a neural network logistic regression model for both UCLP and non-UCLP individuals. METHODS: This study utilizes a novel method incorporating many approaches, such as the bootstrap method, a multi-layer feed-forward neural network, and ordinal logistic regression. A dataset was created based on the following factors: socio-demographic characteristics such as age and gender, as well as cleft type and category of malocclusion associated with the cleft. Training data were used to create a model, whereas testing data were used to validate it. The study is separated into two phases: phase one involves the use of a multilayer neural network and phase two involves the use of an ordinal logistic regression model to analyze the underlying association between cleft and the factors chosen. RESULTS: The findings of the hybrid technique using ordinal logistic regression are discussed, where category acts as both a dependent variable and as the study's output. The ordinal logistic regression was used to classify the dependent variables into three categories. The suggested technique performs exceptionally well, as evidenced by a Predicted Mean Square Error (PMSE) of 2.03%. CONCLUSION: The outcome of the study suggests that there is a strong association between gender, age, and cleft. The difference in width and length of the maxillary arch in UCLP is mainly related to the severity of the cleft and facial growth pattern.

Physicochemical Characterization of Thermally Processed Goose Bone Ash for Bone Regeneration.

Goose bone is traditionally applied for many ailments including bone fractures. Goose bone that consists of calcium phosphate plays a major role in bone regeneration. In this study, the production of goose bone ash (GBA) was translated from a traditional process into one of a laboratory scale via thermal and mechanical methods. The GBA was thermally processed via calcination at 300 °C and 900 °C. The differences in physicochemical properties between studied GBA (SGBA) and commercial GBA (CGBA) were elucidated via Fourier transform infrared (FT-IR), X-ray fluorescence (XRF), X-ray diffraction (XRD) and electron diffraction X-Ray (EDX). The morphological properties of SGBA and CGBA were characterized using field emission scanning electron microscopy (FESEM) in which nano-sized particles were detected. The results showed that the SGBA of 300 °C had comparable physicochemical properties to those of CGBA. A high processing temperature was associated with decreasing organic compounds and increasing crystallinity. The finding from EDX suggests that sintering at 900 °C (SGBA 900) demonstrated the presence of hydroxyapatite in the mineralogical phase and had a Ca/P atomic ratio of 1.64 which is comparable to the ideal stoichiometric ratio of 1.67. Findings from this study could be used for the further exploration of GBA as a potential material for bone regeneration via the elucidation of their biological properties in the next experimental setting.

Potential use of the cusp and crown areas of the maxillary posterior teeth measured with a two-dimensional stereomicroscope for sex determination.

In this study, we aimed to compare the cusp and crown areas of the maxillary first premolar (PM1), second premolar (PM2), and first molar (M1) in males and females in the Malay population and to formulate sex prediction models. For this purpose, the maxillary posterior teeth of 176 dental cast samples (from 88 males and 88 females) were selected and transformed to two-dimensional digital models using 2D-Hirox KH-7700. Cusp and crown area measurements were obtained using Hirox software by tracing the outermost circumference of the tooth cusps. Statistical analysis included independent t-tests, logistic regression analysis, and receiver-operating characteristic (ROC) curves as well as determination of sensitivity and specificity; analysis was performed with SPSS version 26.0. The significance threshold was set at 0.05. All crown and cusp area measurements were significantly larger in males than in females (p < 0.001). The most sexually dimorphic tooth was the first maxillary molar (mean difference, 10.27 mm2), and the most sexually dimorphic cusp was the mesiopalatal cusp (mean difference, 3.67 mm2) of M1. The sex prediction model had a good accuracy, with 80% of selected cases correctly predicted. Hence, we conclude that the maxillary posterior teeth in the Malay population exhibit significant sexual dimorphism, and this information may be used for sex determination as adjuvants along with other procedures.

Validity and reliability of palatal rugae morphometric assessment with 3D laser scanned models

Aim: To assess the reliability and validity of morphometric features on 3D digital models produced by scanning maxillary dental casts of Malaysian Malay subjects. Methods: Dental casts of 20 subjects were scanned using a 3D laser scanner (Next Engine Inc., Santa Monica, California, USA). The palatal rugae morphometric features were assessed on the resulting 3D models using 3-Matic Research 9.0 software (Materialise NV, Heverlee, Belgium). The assessments were repeated by the first and second authors to assess the intra- and interexaminer reliability, respectively. Rugae morphometric features were also evaluated on the conventional plaster models to assess the validity of the 3D method. Results: Kappa values of the validity ranged from 0.807 to 0.922 for rugae shape, size category and direction. The intraclass correlation coefficient (ICC) for rugae number validity was 0.979. For intra-examiner reliability, kappa values ranged from 0.716-1.000 for rugae shape, size category and direction. The ICC for rugae number intra-examiner reliability was 0.949. Kappa values of interexaminer reliability for rugae shape, size category and direction were 0.723-885, while the ICC of rugae number was 0.896. Conclusion: Palatal rugae analyses on 3D digital models scanned by the 3D Next Engine laser scanner using 3-Matic Research 9.0 software are valid and reliable

Clinical Applications of Artificial Intelligence and Machine Learning in Children with Cleft Lip and Palate-A Systematic Review.

OBJECTIVE: The objective of this systematic review was (a) to explore the current clinical applications of AI/ML (Artificial intelligence and Machine learning) techniques in diagnosis and treatment prediction in children with CLP (Cleft lip and palate), (b) to create a qualitative summary of results of the studies retrieved. MATERIALS AND METHODS: An electronic search was carried out using databases such as PubMed, Scopus, and the Web of Science Core Collection. Two reviewers searched the databases separately and concurrently. The initial search was conducted on 6 July 2021. The publishing period was unrestricted; however, the search was limited to articles involving human participants and published in English. Combinations of Medical Subject Headings (MeSH) phrases and free text terms were used as search keywords in each database. The following data was taken from the methods and results sections of the selected papers: The amount of AI training datasets utilized to train the intelligent system, as well as their conditional properties; Unilateral CLP, Bilateral CLP, Unilateral Cleft lip and alveolus, Unilateral cleft lip, Hypernasality, Dental characteristics, and sagittal jaw relationship in children with CLP are among the problems studied. RESULTS: Based on the predefined search strings with accompanying database keywords, a total of 44 articles were found in Scopus, PubMed, and Web of Science search results. After reading the full articles, 12 papers were included for systematic analysis. CONCLUSIONS: Artificial intelligence provides an advanced technology that can be employed in AI-enabled computerized programming software for accurate landmark detection, rapid digital cephalometric analysis, clinical decision-making, and treatment prediction. In children with corrected unilateral cleft lip and palate, ML can help detect cephalometric predictors of future need for orthognathic surgery.

Color variations during digital imaging of facial prostheses subjected to unfiltered ambient light and image calibration techniques within dental clinics: An in vitro analysis.

BACKGROUND: The study aimed to evaluate 1) the amount of color variations presents within clinical images of maxillofacial prosthetic silicone specimens when photographed under different clinically relevant ambient lighting conditions, and 2) whether white balance calibration (WBC) methods were able to mitigate variations in ambient lighting. METHODS: 432 measurements were acquired from standardized images of the pigmented prosthetic silicone specimens within different ambient lighting conditions (i.e., 2 windowed and 2 windowless clinics) at noon with no light modifying apparatus. The specimens were photographed once without any white balance calibration (raw), then independently alongside an 18% neutral gray card and Macbeth color chart for calibration in a post-processing (PPWBC) software, and once after camera calibration (CWBC) using a gray card. The LAB color values were extracted from the images and color variations (ΔE) were calculated after referring to the corresponding spectrophotometric values as control. RESULTS: Images in windowless and windowed clinics exhibited highly significant differences (p < 0.001) with spectrophotometer (control). CWBC demonstrated no significant differences (p > 0.05) in LAB values across windowed clinics. PPWBC using Macbeth color chart produced no significant differences for a* values (p > 0.05) across all clinics while PPWBC by gray card showed no significant differences (p > 0.05) in LAB values when only similar clinics (either windowed or windowless) were compared. CONCLUSION: Significant color variations were present for maxillofacial prosthetic specimens owing to natural ambient light. CWBC and PPWBC using color charts were more suitable for color correction across windowed clinics while CWBC and PPWBC using gray cards had better outcomes across windowless setups.

A virtual analysis of the precision and accuracy of 3-dimensional ear casts generated from smartphone camera images.

STATEMENT OF PROBLEM: The anatomic complexity of the ear challenges conventional maxillofacial prosthetic rehabilitation. The introduction of specialized scanning hardware integrated into computer-aided design and computer-aided manufacturing (CAD-CAM) workflows has mitigated these challenges. Currently, the scanning hardware required for digital data acquisition is expensive and not readily available for prosthodontists in developing regions. PURPOSE: The purpose of this virtual analysis study was to compare the accuracy and precision of 3-dimensional (3D) ear models generated by scanning gypsum casts with a smartphone camera and a desktop laser scanner. MATERIAL AND METHODS: Six ear casts were fabricated from green dental gypsum and scanned with a laser scanner. The resultant 3D models were exported as standard tessellation language (STL) files. A stereophotogrammetry system was fabricated by using a motorized turntable and an automated microcontroller photograph capturing interface. A total of 48 images were captured from 2 angles on the arc (20 degrees and 40 degrees from the base of the turntable) with an image overlap of 15 degrees, controlled by a stepper motor. Ear 1 was placed on the turntable and captured 5 times with smartphone 1 and tested for precision. Then, ears 1 to 6 were scanned once with a laser scanner and with smartphones 1 and 2. The images were converted into 3D casts and compared for accuracy against their laser scanned counterparts for surface area, volume, interpoint mismatches, and spatial overlap. Acceptability thresholds were set at <0.5 mm for interpoint mismatches and >0.70 for spatial overlap. RESULTS: The test for smartphone precision in comparison with that of the laser scanner showed a difference in surface area of 774.22 ±295.27 mm2 (6.9% less area) and in volume of 4228.60 ±2276.89 mm3 (13.4% more volume). Both acceptability thresholds were also met. The test for accuracy among smartphones 1, 2, and the laser scanner showed no statistically significant differences (P>.05) in all 4 parameters among the groups while also meeting both acceptability thresholds. CONCLUSIONS: Smartphone cameras used to capture 48 overlapping gypsum cast ear images in a controlled environment generated 3D models parametrically similar to those produced by standard laser scanners.

Percentage of mesh reduction appropriate for designing digital obturator prostheses on personal computers.

STATEMENT OF PROBLEM: Computer-aided design (CAD) of maxillofacial prostheses is a hardware-intensive process. The greater the mesh detail is, the more processing power is required from the computer. A reduction in mesh quality has been shown to reduce workload on computers, yet no reference value of reduction is present for intraoral prostheses that can be applied during the design. PURPOSE: The purpose of this simulation study was to establish a reference percentage value that can be used to effectively reduce the size and polygons of the 3D mesh without drastically affecting the dimensions of the prosthesis itself. MATERIAL AND METHODS: Fifteen different maxillary palatal defects were simulated on a dental cast and scanned to create 3D casts. Digital bulbs were fabricated from the casts. Conventional bulbs for the defects were fabricated, scanned, and compared with the digital bulb to serve as a control. The polygon parameters of digital bulbs were then reduced by different percentages (75%, 50%, 25%, 10%, 5%, and 1% of the original mesh) which created a total of 105 meshes across 7 mesh groups. The reduced mesh files were compared individually with the original design in an open-source point cloud comparison software program. The parameters of comparison used in this study were Hausdorff distance (HD), Dice similarity coefficient (DSC), and volume. RESULTS: The reduction in file size was directly proportional to the amount of mesh reduction. There were minute yet insignificant differences in volume (P>.05) across all mesh groups, with significant differences (P<.001) in HD. The differences were, however, only found with DB1. DSC showed a progressive dissimilarity until DB25 (0.17%), after which the increase was more prominent (0.46% to 4.02%). CONCLUSIONS: A reduction of up to 75% polygons (25% of the original mesh) was effectively carried out on simulated casts without substantially affecting the amount of similarity in volume and geometry.

Biomechanics in Removable Partial Dentures: A Literature Review of FEA-Based Studies.

The present study was aimed at reviewing the studies that used finite element analysis (FEA) to estimate the biomechanical stress arising in removable partial dentures (RPDs) and how to optimize it. A literature survey was conducted for the English full-text articles, which used only FEA to estimate the stress developed in RPDs from Jan 2000 to May 2021. In RPDs, the retaining and supporting structures are subjected to dynamic loads during insertion and removal of the prosthesis as well as during function. The majority of stresses in free-end saddle (FES) RPDs are concentrated in the shoulder of the clasp, the horizontal curvature of the gingival approaching clasp, and the part of the major connector next to terminal abutments. Clasps fabricated from flexible materials were beneficial to eliminate the stress in the abutment, while rigid materials were preferred for major connectors to eliminate the displacement of the prosthesis. In implant-assisted RPD, the implant receive the majority of the load, thereby reducing the stress on the abutment and reducing the displacement of the prosthesis. The amount of stress in the implant decreases with zero or minimal angulation, using long and wide implants, and when the implants are placed in the first molar area.

Biomechanical Stress in Obturator Prostheses: A Systematic Review of Finite Element Studies.

AIM: This systematic review is aimed at investigating the biomechanical stress that develops in the maxillofacial prostheses (MFP) and supporting structures and methods to optimize it. Design and Methods. A literature survey was conducted for full-text English articles which used FEA to examine the stress developed in conventional and implant-assisted MFPs from January 2010 to December 2020. RESULTS: 87 articles were screened to get an update on the desired information. 74 were excluded based on a complete screening, and finally, 13 articles were recruited for complete reviewing. Discussion. The MFP is subjected to stress, which is reflected in the form of compressive and tensile strengths. The stress is mainly concentrated the resection line and around the apices of roots of teeth next to the defect. Diversity of designs and techniques were introduced to optimize the stress distribution, such as modification of the clasp design, using materials with different mechanical properties for dentures base and retainer, use of dental (DI) and/or zygomatic implants (ZI), and free flap reconstruction before prosthetic rehabilitation. CONCLUSION: Using ZI in the defective side of the dentulous maxillary defect and defective and nondefective side of the edentulous maxillary defect was found more advantageous, in terms of compression and tensile stress and retention, when compared with DI and free flap reconstruction.

Machine Learning and Intelligent Diagnostics in Dental and Orofacial Pain Management: A Systematic Review.

Purpose: The study explored the clinical influence, effectiveness, limitations, and human comparison outcomes of machine learning in diagnosing (1) dental diseases, (2) periodontal diseases, (3) trauma and neuralgias, (4) cysts and tumors, (5) glandular disorders, and (6) bone and temporomandibular joint as possible causes of dental and orofacial pain. Method: Scopus, PubMed, and Web of Science (all databases) were searched by 2 reviewers until 29th October 2020. Articles were screened and narratively synthesized according to PRISMA-DTA guidelines based on predefined eligibility criteria. Articles that made direct reference test comparisons to human clinicians were evaluated using the MI-CLAIM checklist. The risk of bias was assessed by JBI-DTA critical appraisal, and certainty of the evidence was evaluated using the GRADE approach. Information regarding the quantification method of dental pain and disease, the conditional characteristics of both training and test data cohort in the machine learning, diagnostic outcomes, and diagnostic test comparisons with clinicians, where applicable, were extracted. Results: 34 eligible articles were found for data synthesis, of which 8 articles made direct reference comparisons to human clinicians. 7 papers scored over 13 (out of the evaluated 15 points) in the MI-CLAIM approach with all papers scoring 5+ (out of 7) in JBI-DTA appraisals. GRADE approach revealed serious risks of bias and inconsistencies with most studies containing more positive cases than their true prevalence in order to facilitate machine learning. Patient-perceived symptoms and clinical history were generally found to be less reliable than radiographs or histology for training accurate machine learning models. A low agreement level between clinicians training the models was suggested to have a negative impact on the prediction accuracy. Reference comparisons found nonspecialized clinicians with less than 3 years of experience to be disadvantaged against trained models. Conclusion: Machine learning in dental and orofacial healthcare has shown respectable results in diagnosing diseases with symptomatic pain and with improved future iterations and can be used as a diagnostic aid in the clinics. The current review did not internally analyze the machine learning models and their respective algorithms, nor consider the confounding variables and factors responsible for shaping the orofacial disorders responsible for eliciting pain.

Using 21st-Century Technologies to Determine the Cognitive Capabilities of a 11,000-Year-Old Perak Man Who Had Brachymesophalangia Type A2.

Perak Man, named after the state where the skeleton was found, was the most complete skeleton found in Southeast Asia. The funerary artefacts indicate that Perak Man was highly respected, as he was buried at the centre of the highest cave in Lenggong, and he was the only person buried there. A copy of the original skull was made using computed tomography (CT) and 3D printing. Based on the internal structure of the reconstructed skull, the estimated intracranial volume (ICV) is 1,204.91 mL. The hypothetical face of Perak Man was reconstructed according to established forensic methods. Based on his presumed status, Perak Man was likely a respected person in the group and, perhaps, a shaman and the most knowledgeable person in the group regarding survival, hunting, gathering and other aspects of Palaeolithic daily life.

Optimization of Prosthodontic Computer-Aided Designed Models: A Virtual Evaluation of Mesh Quality Reduction Using Open Source Software.

PURPOSE: Mesh optimization reduces the texture quality of 3D models in order to reduce storage file size and computational load on a personal computer. This study aims to explore mesh optimization using open source (free) software in the context of prosthodontic application. MATERIALS AND METHODS: An auricular prosthesis, a complete denture, and anterior and posterior crowns were constructed using conventional methods and laser scanned to create computerized 3D meshes. The meshes were optimized independently by four computer-aided design software (Meshmixer, Meshlab, Blender, and SculptGL) to 100%, 90%, 75%, 50%, and 25% levels of original file size. Upon optimization, the following parameters were virtually evaluated and compared; mesh vertices, file size, mesh surface area (SA), mesh volume (V), interpoint discrepancies (geometric similarity based on virtual point overlapping), and spatial similarity (volumetric similarity based on shape overlapping). The influence of software and optimization on surface area and volume of each prosthesis was evaluated independently using multiple linear regression. RESULTS: There were clear observable differences in vertices, file size, surface area, and volume. The choice of software significantly influenced the overall virtual parameters of auricular prosthesis [SA: F(4,15) = 12.93, R2 = 0.67, p < 0.001. V: F(4,15) = 9.33, R2 = 0.64, p < 0.001] and complete denture [SA: F(4,15) = 10.81, R2 = 0.67, p < 0.001. V: F(4,15) = 3.50, R2 = 0.34, p = 0.030] across optimization levels. Interpoint discrepancies were however limited to <0.1mm and volumetric similarity was >97%. CONCLUSION: Open-source mesh optimization of smaller dental prostheses in this study produced minimal loss of geometric and volumetric details. SculptGL models were most influenced by the amount of optimization performed.

Detailed Anatomical Volumetric Study of Deep Nuclei of Brain and Other Structures Between Parkinson's Disease Patients Who Had Deep Brain Stimulation and Control Group.

BACKGROUND: Deep brain stimulation (DBS) was pioneered by Neuroscience team of Hospital Universiti Sains Malaysia (HUSM) nearly a decade ago to treat advanced medically refractory idiopathic Parkinson's disease (IPD) patients. OBJECTIVES: Brain volume reduction occurs with age, especially in Parkinson plus syndrome or psychiatric disorders. We searched to define the degree of volume discrepancy in advanced IPD patients and correlate the anatomical volumetric changes to motor symptoms and cognitive function. METHODS: We determined the magnetic resonance imaging (MRI)-based volumetry of deep brain nuclei and brain structures of DBS-IPD group and matched controls. RESULTS: DBS-IPD group had significant deep nuclei atrophy and volume discrepancy, yet none had cognitive or psychobehavioural disturbances. Globus pallidus volume showed positive correlation to higher mental function. CONCLUSION: The morphometric changes and clinical severity discrepancy in IPD may imply a more complex degenerative mechanism involving multiple neural pathways. Such alteration could be early changes before clinical manifestation.

Designing 3D prosthetic templates for maxillofacial defect rehabilitation: A comparative analysis of different virtual workflows.

OBJECTIVE: To design and compare the outcome of commercial (CS) and open source (OS) software-based 3D prosthetic templates for rehabilitation of maxillofacial defects using a low powered personal computer setup. METHOD: Medical image data for five types of defects were selected, segmented, converted and decimated to 3D polygon models on a personal computer. The models were transferred to a computer aided design (CAD) software which aided in designing the prosthesis according to the virtual models. Two templates were designed for each defect, one by an OS (free) system and one by CS. The parameters for analyses were the virtual volume, Dice similarity coefficient (DSC) and Hausdorff's distance (HD) and were executed by the OS point cloud comparison tool. RESULT: There was no significant difference (p > 0.05) between CS and OS when comparing the volume of the template outputs. While HD was within 0.05-4.33 mm, evaluation of the percentage similarity and spatial overlap following the DSC showed an average similarity of 67.7% between the two groups. The highest similarity was with orbito-facial prostheses (88.5%) and the lowest with facial plate prosthetics (28.7%). CONCLUSION: Although CS and OS pipelines are capable of producing templates which are aesthetically and volumetrically similar, there are slight comparative discrepancies in the landmark position and spatial overlap. This is dependent on the software, associated commands and experienced decision-making. CAD-based templates can be planned on current personal computers following appropriate decimation.

Patient-Specific Reconstruction Utilizing Computer Assisted Three-Dimensional Modelling for Partial Bone Flap Defect in Hybrid Cranioplasty.

PURPOSE: Decompressive craniectomy is a life-saving procedure in the setting of malignant brain swelling. Patients who survive require cranioplasty for anatomical reconstruction and cerebral protection. Autologous cranioplasty remains the commonest practice nowadays, but partial bone flap defects are frequently encountered. The authors, therefore, seek to develop a new technique of reconstruction for cranioplasty candidate with partial bone flap defect utilizing computer-assisted 3D modeling and printing. METHODS: A prospective study was conducted to evaluate the outcome of a new reconstruction technique that produces patient-specific hybrid polymethyl methacrylate-autologous cranial implant. Computer-assisted 3D modeling and printing was utilized to produce patient-specific molds, which allowed real-time reconstruction of bone flap with partial defect intra-operatively. RESULTS: Outcome assessment for 11 patients at 6 weeks and 3 months post-operatively revealed satisfactory implant alignment with favorable cosmesis. The mean visual analog scale for cosmesis was 91. Mean implant size was 50cm, and the mean duration of intra-operative reconstruction was 30 minutes. All of them revealed improvement in quality of life following surgery as measured by the SF-36 score. Cost analysis revealed that this technique is more cost-effective compared to customized cranial prosthesis. CONCLUSION: This new technique and approach produce hybrid autologous-alloplastic bone flap that resulted in satisfactory implant alignment and favorable cosmetic outcome with relatively low costs.