Doctor Scientiae Dentium - DSc(Dent) (Odontology)

Permanent URI for this collectionhttps://hdl.handle.net/10566/10626

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Characterization of the cadmium telluride photon-counting sensor as applies to its use in the QRMaster-P panoramic machine
(University of the Western Cape, 2013) Langlais, Robert Paul
This study was undertaken to perform in vitro investigations of several potential important clinical applications of a new Cadmium Telluride Photon Counting (CdTe PC) sensor fitted to a newly designed panoramic machine. The study was divided into three parts and each of the three clinical applications was highly relevant to the current clinical practice of dentistry. More importantly, these functions were either not clinically possible with the use of existing panoramic machines or when standard panoramic devices were employed, clinically inaccurate data was obtained from the images. The aims of the three projects were as follows: Project 1. To investigate whether bone mineral density (quality) could be determined more accurately using the QR Master-P test machine than by one representative standard panoramic device and one representative hybrid pan cone beam computed tomography (CBCT) scanner in the standard pan mode; Project 2. To determine whether different restorative materials could be separated from each other and identified using the QR Master-P test device as compared to one standard panoramic machine and one hybrid pan-CBCT device in the standard pan mode and Project 3. To determine whether angular measurements could be made accurately using the QR Master-P test system as compared to a standard panoramic machine. Methodology The first project involved the use of a fiduciary hydroxyapatite object consisting of several known levels of hydroxyapatite mineral concentration and placed in an anatomical phantom with the upper jaw removed to make room for the placement of the fiduciary hydroxyapatite object in right side up and upside down configurations and in various locations on the occlusal plane of the mandible. The anatomical phantom was carefully positioned in a standard pan machine and a hybrid pan-CBCT device in standard pan mode and also in the new QR Master-P test pan scanner fitted with the CdTe PC sensor. The second project involved use of a standardized test block containing a variety of restorative (tooth filling) materials which was placed within a specially designed custom manufactured anatomical phantom. The test device and phantom were carefully positioned in a standard pan machine, in a hybrid pan-CBCT device in standard pan mode and in the new QR Master-P scanner fitted with the CdTe PC sensor. The third project involved the use of another phantom containing a 1 mm Wire grid meshwork within the central plane of the mandible and maxilla of the phantom. The phantom was carefully positioned in one standard pan machine and in the QR Master-P test device. The resultant image of the wire meshwork within the jaws allowed for the assessment of the accuracy of measured 45 and 90 degree angles. Results In project 1, it was found that the CdTe PC-fitted machine could more consistently separate each of the hydroxyapatite concentrations in all of the positioning configurations and locations including places where the effects of beam hardening would affect the image. However in its present form the QR Master-P test device is not appropriate for use in accurately determining bone quality. In project 2, the QR Master-P test machine fitted with the CdTe PC sensor did not distinguish well between all of the restorative materials; however it was superior to the other machines for the distinction of several of the dental filling compounds. In project 3 the test angles as measured from the wire grid within the Katsumata phantom proved to deviate from the known 45 and 90 degree values and each of the three individual measurements of each angle varied to some degree. Though the test machine performed better than the standard device, some measurement inaccuracy was present and the measurements were only slightly better in the test machine. Discussion The findings from Project 1 indicated that because the new sensor and software can separate the image energy data into three different bins, and using the dual energy equation which is possible in the QR Master-P device, the atomic or "Z" number and the electron density of the components of the unknown material can be separated and determined which in tum can identify the specific substances. This could be achieved with a simple low dose panoramic scan without the need for fiduciary standardization objects as are presently recommended or for higher dose medical computed tomography measurements or a medical dual x-ray absorptiometry (DXA) scan (unavailable in dental offices) which were considered the gold standards. In Project 2, the further development of the capability to apply the dual energy equation to accurately assess bone mineral quality which is not possible currently with a simple pan image is now recognized to be possible with the QR Master P system. Secondly when no previous history is available, this feature can be used to identify the contents of unknown restorative materials for the identification of the individual components. This information could be further applied to helping persons to overcome the debilitating oral effects of allergic reactions to these materials. In Project 3, it was found that more accurate angular measurements can be obtained by developing and applying a known software 3D surface mapping to produce 3D vector-based absolute angular measurements. Because of the QR Master-P machine's unique design and software capabilities, such a modification is entirely possible and could improve the treatment outcomes of millions of patients currently receiving less than accurate orthodontic diagnostic measurements and resulting less than ideal treatments which in the long term may in some cases be responsible for the breakdown and failure to achieve an esthetically pleasing, stable and functional dentition. Conclusions With respect to all three projects, it was concluded the QR Master-P test device did perform better in varying degrees to both of the standard pan machines. It was further postulated that based on the sensor's reported design and lower dose potential, these improved data could be obtained with as much as 3-5 times less radiation. This latter feature alone would in and of itself further endorse the preferential clinical use of the QR Master-P system at this time. Furthermore, these results indicate the methodologies as developed for this study can be used to test future outcomes including but not limited to: more sophisticated analyses to determine bone quality, accurate analysis and identification of unknown materials in patients' teeth and mouths; to obtain more accurate angular measurements which not only apply to orthodontic treatments, but also to implant placement next to adjacent teeth and abutment alignment for the design prosthetic devices. A hybrid pan-cone beam computed tomography version of the QR Master-P system which is currently under development may also prove to have similar capabilities.
Forensic Radiographic Identification Using Manipulated Digital Dental Images
(University of the Western Cape, 1996) Wood, Robert Edgar; Nortjé, C.J.
A technique was developed for the assessment of forensic identification using dental radiographs. The technique involved the digitisation of dental radiographs, cutting of a horizontal section from an antemortem radiograph and superimposing it over the same geographic location on the postmortem radiograph. The technique was useful in vitro and in an in vitro mock mass disaster. It was accurate within both the paediatric and permanent dentition and not useful in subjects with changing dentitions (mixed dentition). Image density (with and without optical enhancement) did not prove to be an impediment to the technique although extremes of image contrast did. Within the range of dental xray generators settings, contrast could be altered in a manner to allow matching. Differences in the vertical angulation of the x-ray beam did not influence the technique although horizontal angulation was a critical factor. Alterations in focal-film distance did not adversely affect the use of this technique. The three different scanning systems used were .all adequate for the purpose of the technique and the images could be compressed and transferred with little difficulty. Analysis of a group of actual Coroner's cases proved the technique to be useful in a timely fashion, for actual field identifications with minimal inter and intra operator error.
Oral submucous fibrosis in Durban, Natal: a study of its epidemiology, aetiology and morphological features
(Stellenbosch University, 1985) Seedat, Hoosen Ahmed; van Wyk, C W
There is no satisfactory statistical record of oral submucous fibrosis in the Republic of South Africa or India. The present prevalence study of OSF among Indians in the municipal area of Durban was planned by the Institute for Biostatistics of the South African Medical Research Council. The sampling consisted of a stratified random survey and the total number of subjects examined was 2 058. They were stratified into the age groups: 10-14, 15-24, 25-34, 35-44, 45-54, 55-64, 65+ years, and into sexes. Each age group included 294 people (147 males and 147 females). From the 29 suburbs included in this survey 147 points were sampled. The number of sampling points was calculated proportional to the population size. At each sampling point one individual of each sex in each age group was selected i.e. 14 individuals at each sampling point.
Head Injuries: Risk factors and consequences
(University of the Western Cape, 2002) Lalloo, Ratilal; Sheiham, Aubrey
Injuries, and head injuries in particular, are a common cause of childhood, adolescent and young adulthood morbidity and mortality. The risk factors for injuries in general have been well researched. But it remains uncertain whether these factors are similar for specific injuries, such as head injuries. The inter-relationships between individual and environmental risk factors are difficult to study. Whilst much is know of the short-term consequences of head injuries, relatively little information is available on their long-term conseque~ces. The follow-up period in most research is short (often less than 1 year) and studies are weak in terms of design. Studies generally find a variety of social, cognitive and psychological consequences in children and young adults experiencing head injuries. This study assessed in two large, nationally representative samples, a 1946 birth cohort and a 1997 cross-sectional health survey: 1) the occurrence and risk factors for childhood, adolescent and early adulthood head and other injuries, and 2) the long-term cognitive and psychiatric effects of skull injuries. The overall findings for the risk factors across the two data sets and over 5 decades of data collection were strikingly similar. Maleness was a major risk factor for the head and other injuries. Some of the behaviour and personality factors such as hyperactivity and being neurotic, even after adjusting for sex, socioeconomic status and family type, remained significantly related to injuries, particularly those affecting the head region. A clustering of demographic, socioeconomic, family and behavioural risk factors significantly increased the likelihood of injuries, particularly recurring injuries with at least one being a head injury. In the unadjusted analyses socioeconomic status and family type were less consistently related to injuries. The long-term psychiatric and cognitive consequences of skull injuries causing concussion and skull fractures in childhood and early adulthood were negligible. Other childhood factors such as educational ability, behaviour and personality, and level of education achieved were more predictive of psychiatric symptoms and cognitive problems in adulthood. This study suggests that children and adolescents with behavioural and personality problems were at greater risk of head and other injuries in childhood, adolescence and later in adulthood. Children and adolescents with behavioural and personality problems were more likely to live in manual social class families and families with a single parent or stepparent. This combination of behavioural problems and deprived socioeconomic and family circumstances may increase tendencies for violent behaviour, alcohol dependence and manual occupations later in adulthood, which all increase the risk of injuries. There is therefore a need to identify children and adolescents with behavioural and personality problems as early as possible to prevent the impact in the short- and longterm. This will not only reduce the burden of injuries but also the many other consequence of behavioural and personality problems, particularly when located within deprived socioeconomic and family circumstances.
‘Recommendations for the development of a framework for radiological imaging studies during implant therapy in SA’
(University of the Western Cape, 2021) Beshtawi, Khaled Raed; Chetty, M.
Radiographic examination is an essential facet of dental implant therapy, and the success of this therapy depends on a suitable treatment based on adequate clinical and radiographic information. International organisational bodies have published guidelines on the use of radiographic imaging during implant therapy, but since the cone beam computed tomography modality became available, a need for the development of comprehensive imaging guidelines to limit the misuse of this modality became necessary. There is a lack of stringency regarding the recommendations and guidelines on radiographic imaging modalities used during implant therapy. This is due to variations in practice, experience, and socioeconomic factors. The most recent published global guidelines and recommendations and their relevance to dental implant therapy are described in this chapter.
Synthesis and characterization of biopolymer nanoapatite composite electrospun bioactive scaffold: A potential application for guided tissue/bone regeneration
(University of the Western Cape, 2019) Nadeem, Muhammad; Stephen, Lawrence
Search for an ideal scaffold for guided tissue/bone (GTR/GBR) regeneration continues as till now none of the commercially available GTR/GBR membrane fulfils the desired criteria. Currently, a variety of new materials and techniques have been investigated all over the world to improve the properties of GTR/GBR membranes. In the recent past three dimensional bioactive scaffolds composed of natural polymers have gained enormous popularity as potential future GTR/GBR devices. Electrospinning has emerged as one of the relatively simple, cost effective and efficient technique to fabricate three dimensional nanofibrous scaffolds in the field of tissue engineering. The rationale of this project is to investigate the natural polymers based bioactive nanofibrous scaffolds for GTR/GBR applications in the field of Periodontology.
Dental maturation of the permanent mandibular teeth of South African children and the relation to chronological age
(2009) Phillips, Vincent Michael; Nortjé, C.J.; Morris, A.G.
Age estimation of the skeletal remains of children can be accomplished by examination of the ossification centres and the fusion of the epiphyseal plates of long bones. Dental age estimation is done by examining the eruption of the deciduous and permanent teeth. Both these methods are inaccurate and are subject to the nutritional status of the individual. A more accurate method of age estimation is by the examination of radiographic images of the developmental stages of the tooth crown and root formation. Two methods of dental age estimation used are those of Moorrees, Fanning and Hunt (1963) (MFH) and that of Demirjian, Goldstein and Tanner (1973) (DGT). These methods were tested on a sample of 913 Tygerberg dental patients; a random mixture of Caucasoid and Khoisanoid children. The MFH method under-estimated the ages of the sample by an average of 0.91 years and the DGT method over-estimated the ages by an average of 0.89 years. Samples of Indian and Negroid children from Kwa-Zulu Natal were tested in a similar manner and the results showed similar under and over-estimation of the ages by these methods. The Negroid children were labelled the Zulu sample. Correction factors were derived for the MFH and DGT methods of dental age estimation when used on Tygerberg, Indian and Zulu children. These correction factors were tested on the samples and found to improve the accuracy of the age estimation methods of MFH and DGT significantly.A second sample group of Tygerberg, Indian and Zulu children were then tested firstly using the standard method of MFH and DGT and the using the correction factors. The results showed that the correction factors improved the age estimation on these samples except in the case of the DGT method on Zulu children. A sample of Xhosa speaking children were added to the two Zulu samples and made an Nguni sample. The Tygerberg samples were combined as were the Indian samples to form data bases for the construction of dental age related tables for Tygerberg, Indian and Nguni children. These tables show that there are distinct differences in the ages at which the teeth develop in the different sample groups and that dental age related tables are necessary for children of different population origins. Statistical analysis of the age related tables from this study (Phillips Tables) show these tables are more accurate in the age estimation of South African children.

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