A pilot study for the digital replacement of a distorted dentition acquired by Cone Beam Computed Tomography (CBCT)

Abstract Introduction: Cone beam CT (CBCT) is becoming a routine imaging modality designed for the maxillofacial region. Imaging patients with intra-oral metallic objects cause streak artefacts. Artefacts impair any virtual model by obliterating the teeth. This is a major obstacle for occlusal registration and the fabrication of orthognathic wafers to guide the surgical correction of dentofacial deformities. Aims and Objectives: To develop a method of replacing the inaccurate CBCT images of the dentition with an accurate representation and test the feasibility of the technique in the clinical environment. Materials and Method: Impressions of the teeth are acquired and acrylic baseplates constructed on dental casts incorporating radiopaque registration markers. The appliances are fitted and a preoperative CBCT is performed. Impressions are taken of the dentition with the devices in situ and subsequent dental models produced. The models are scanned to produce a virtual model. Both images of the patient and the model are imported into a virtual reality software program and aligned on the virtual markers. This allows the alignment of the dentition without relying on the teeth for superimposition. The occlusal surfaces of the dentition can be replaced with the occlusal image of the model. Results: The absolute mean distance of the mesh between the markers in the skulls was in the region of 0.09mm ± 0.03mm; the replacement dentition had an absolute mean distance of about 0.24mm ± 0.09mm. In patients the absolute mean distance between markers increased to 0.14mm ± 0.03mm. It was not possible to establish the discrepancies in the patient’s dentition, since the original image of the dentition is inherently inaccurate. Conclusion: It is possible to replace the CBCT virtual dentition of cadaveric skulls with an accurate representation to create a composite skull. The feasibility study was successful in the clinical arena. This could be a significant advancement in the accuracy of surgical prediction planning, with the ultimate goal of fabrication of a physical orthognathic wafer using reverse engineering

Three-dimensional assessment of dentofacial deformity in children with clefts

Background: Changes in clinical management; advances in non-invasive three-dimensional imaging; developments in methods of shape analysis. Aim: To assess three-dimensional dentofacial deformity with a view to early appraisal of primary surgical outcome. Results: Significant differences in upper lip morphology were found between the cleft children and their unaffected peers; nasal asymmetry that became more obvious in function was noted in cleft children; the maxillary dental arches of the children with repaired cleft palate were shallow, short and narrow; and the dental arch, deformity and the facial soft tissue deformity were unrelated. Contributions to the field: It has been shown that deviation from normal could be detected as young as 3 years of age using computerised stereophotogrammetry; preliminary, objective, three-dimensional analysis of facial function has been completed in young children; the accuracy of three-dimensional CT scanning of dentate study models and the time cost of data collection were quantified; and this study has produced a body of three-dimensional data that can test and support analytical advances

Retrospective evaluation of dento-alveolar morphology after fixed orthodontic treatment at HUSM: laser scanning 3D model

The purpose of this study was to evaluate the validity and reliability of orthodontic measurements made on laser scanned 3D models created with NextEngine laser scanner and ScanStudioHD software and to evaluate arch dimensional changes in subjects treated with extraction and non-extraction after conventional orthodontic treatment using laser scanned 3D models. Dental models of 104 patients (416 dental models) were randomly selected from the archives of School of Dental Sciences, Universiti Sains Malaysia. Scanning, imaging and measuring were completed to achieve objectives. A total of 100 set were measured by Mitutoyo digital caliper (DC) and ScanStudio HD software to achieve first objective and 416 dental models were used to achieve the second objective. Statistical comparisons were performed using paired t-test, independent t-test and RM ANCOVA. The validity (accuracy) of the digital measurements showed no statistical differences in any of the measurements performed. The reliability coefficient values were comparable between laser scanned 3D models and measurements using DC and the values of coefficient were in the range of strong correlation. The results showed that linear measurements of dental models using laser scanned 3D models are valid and reliable and can be used for various clinical orthodontic procedures. Significant differences were found in pre-treatment groups for 1-PMD and LII in maxillary arch whereas there were significant changes in all parameters except for ICD, 1-PMD, LII and OB in post-treatment group. Significant differences were observed in all parameters except for ICD and 1-PMD in XLA group. In non-extraction group, significant changes were observed in all parameters except in IMD, MCF and OJ. There were significant changes in all parameters of mandibular arch except for ICD, 1- PMD and A/L in pretreatment group whereas there were significant changes in all parameters except for ICD, 1-PMD and LII in post-treatment group. For pre and posttreatment differences, the changes of mandibular dental arch were significant in all variables except A/P in non-extraction group whereas all parameters except for 2-PMD, IMD and MCF were changed significantly in extraction group. The results of the present study showed conventional orthodontic treatment with extraction and non-extraction pattern potentially producing statistically significant changes of the dental arches. Thus, this finding would be beneficial for orthodontic patients at Hospital Universiti Sains Malaysia (HUSM) as 3D record for comprehensive diagnosis and consequently successful orthodontic treatment planning

The rephonologization of Hausa loanwords from English: an optimality theory analysis

Faculty of Humanities School of Literature, Language and Media University of the Witwatersrand A Master’s DissertationThis study investigates how Hausa, a West Chadic language (Afro Asiatic phyla) remodells loanwords from English (Indo – European) to suit its pre-existing phonology. Loanword adaptation is quite inevitable due to the fact that languages of the world differ, one from another in many ways: phonological, syntactical, morphological and so on (Inkelas & Zoll, 2003, p. 1). Based on this claim, receptor languages therefore employ ways to rephonologize new words borrowed into their vocabularies to fit, and to conform to native structure demands. Hausa disallows complex onsets, preferably operates open syllables and avoids consonant clustering in word-medial positions as at its best can tolerate no more than a single consonant at a syllable edge (Clements, 2000; Han, 2009). On the contrary, English permits complex onsets as well as closed syllables (Skandera & Burleigh, 2005). Such distinctions in both phonologies motivate for loanword adaptation. Hausa therefore employs repair strategies such as vowel epenthesis, consonant deletions and segmental substitutions and/or replacements (Newman, 2000; Abubakre, 2008; Alqhatani & Musa, 2014) to remodell loanwords. For analytical purposes, this research adopts theoretical tools of Feature Geometry (FG) (Clements & Hume, 1995) and Optimality Theory (OT) (Prince & Smolensky, 2004) to clearly illustrate how loanwords are modified to satisfy Hausa native demands (Kadenge, 2012). Vowel epenthesis in Hausa involves two main strategies: consonantal assimilation and default insertions. During consonantal assimilation, coronal and labial segments spread place features unto the epenthetic segment in the process determining the vowel type and/or quality, while in the case of default insertions, fresh segments are introduced context independently. Concerning segmental substitutions, most notably are English consonants /p/ and /v/ maximally replaced with similar ones, [f] and [b] that exist in Hausa on the basis that former and latter segments share same phonation feature

Observations on the dynamic control of an articulatory synthesizer using speech production data

This dissertation explores the automatic generation of gestural score based control structures for a three-dimensional articulatory speech synthesizer. The gestural scores are optimized in an articulatory resynthesis paradigm using a dynamic programming algorithm and a cost function which measures the deviation from a gold standard in the form of natural speech production data. This data had been recorded using electromagnetic articulography, from the same speaker to which the synthesizer\u27s vocal tract model had previously been adapted. Future work to create an English voice for the synthesizer and integrate it into a text-to-speech platform is outlined.Die vorliegende Dissertation untersucht die automatische Erzeugung von gesturalpartiturbasierten Steuerdaten für ein dreidimensionales artikulatorisches Sprachsynthesesystem. Die gesturalen Partituren werden in einem artikulatorischen Resynthese-Paradigma mittels dynamischer Programmierung optimiert, unter Zuhilfenahme einer Kostenfunktion, die den Abstand zu einem "Gold Standard" in Form natürlicher Sprachproduktionsdaten mißt. Diese Daten waren mit elektromagnetischer Artikulographie am selben Sprecher aufgenommen worden, an den zuvor das Vokaltraktmodell des Synthesesystems angepaßt worden war. Weiterführende Forschung, eine englische Stimme für das Synthesesystem zu erzeugen und sie in eine Text-to-Speech-Plattform einzubetten, wird umrissen

Humanity from African Naissance to Coming Millennia

Humanity From African Naissance to Coming Millennia arises out of the world's first Dual Congress that was held at Sun City (South Africa) in 1998 that refers to a conjoint, integrated meeting of two international scientific associations, the International Association for the Study of Human Palaeontology - IV Congress - and the International Association of Human Biologists. The volume includes 39 refereed papers covering a wide range of topics, from Human Biology, Human Evolution (Emerging Homo, Evolving Homo, Early Modern Humans), Dating, Taxonomy and Systematics, Diet, Brain Evolution, offering the most recent analyses and interpretations in different areas of evolutionary anthropology.Humanity From African Naissance to Coming Millennia arises out of the world's first Dual Congress that was held at Sun City (South Africa) in 1998 that refers to a conjoint, integrated meeting of two international scientific associations, the International Association for the Study of Human Palaeontology - IV Congress - and the International Association of Human Biologists. The volume includes 39 refereed papers covering a wide range of topics, from Human Biology, Human Evolution (Emerging Homo, Evolving Homo, Early Modern Humans), Dating, Taxonomy and Systematics, Diet, Brain Evolution, offering the most recent analyses and interpretations in different areas of evolutionary anthropology

Digital Workflows and Material Sciences in Dental Medicine

The trend of digitalization is an omnipresent phenomenon nowadays – in social life and in the dental community. Advancement in digital technology has fostered research into new dental materials for the use of these workflows, particularly in the field of prosthodontics and oral implantology.CAD/CAM-technology has been the game changer for the production of tooth-borne and implant-supported (monolithic) reconstructions: from optical scanning, to on-screen designing, and rapid prototyping using milling or 3D-printing. In this context, the continuous development and speedy progress in digital workflows and dental materials ensure new opportunities in dentistry.The objective of this Special Issue is to provide an update on the current knowledge with state-of-the-art theory and practical information on digital workflows to determine the uptake of technological innovations in dental materials science. In addition, emphasis is placed on identifying future research needs to manage the continuous increase in digitalization in combination with dental materials and to accomplish their clinical translation.This Special Issue welcomes all types of studies and reviews considering the perspectives of the various stakeholders with regard to digital dentistry and dental materials