Background: The width of the facial alveolar bone wall is crucial for long term successful esthetic outcomes of implants immediately placed into extraction sockets. A threshold of 2 mm is recommended to minimize buccal vertical bone resorption. Aim: To assess the width of the facial alveolar bone wall using cone-beam computed tomography images (CBCT). Methods: Retrospective CBCT images were acquired from a representative sample of Asians using the i-CAT® classic system with a 0.4 mm voxel size. At random, 200 CBCT images were selected according to predefined criteria. The DICOM file was imported into the i-Cat Vision® software. In the panoramic screen, the middle of each tooth was selected and, in the sagittal window, the middle cross section was selected for performing the measurements using a computer. The vertical distance from the alveolar crest (BC) - CEJ was measured. The width of the facial alveolar bone wall was measured at three locations: 1, 3, and 5 mm apical to BC. Descriptive statistics, frequency analyses, and multi-level comparisons were performed. Results: The sample consisted of 74 males and 126 females (mean age of 37.2 years; range 17-82 years). A total of 3618 teeth were assessed. There was no significant difference between the values of right and left sides, or between genders. However, statistically significant differences were observed between age groups at all levels. The distance from CEJ-BC varied from 0.4 to 4mm, with an overall tendency to increase with age. The mean width of the facial alveolar bone wall at anterior teeth was 0.9 mm and increased towards posterior regions. Rarely, a width of 2 mm was yielded (0.6-1.8 % for anterior teeth, 0.7- 30.8 % for posterior teeth). At a 5mm distance from BC, minimal widths of facial alveolar bone were identified for the anterior teeth. The frequency of dehiscence ranged from 9.9- 51.6 % for anterior and 3.1- 53.6 % for posterior teeth, respectively. Conclusion and clinical implications: A thin facial alveolar bone wall was usually present in both jaws. Hence, for most patients, adjunctive bone augmentation may be needed when installing implants in areas of esthetic concern. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Planar bone scintigraphy is highly sensitive but it may not be sensitive enough to detect subtle lesions in complex bony structures such as the spine. The accurate anatomic localisation of lesions in regions such as this is also limited using planar images. Single Photon Emission Computed Tomography (SPECT) results in a higher lesion contrast resulting in an improved sensitivity for the detection of subtle lesions. SPECT also enables improved lesion localisation, often valuable in distinguishing benign from malignant disease in the spine. A number of previous studies have demonstrated that the addition of SPECT of the spine significantly enhances the value of bone scintigraphy for the detection of bone metastases compared to planar imaging alone. These studies were however not done in the African context where patients typically present with more advanced disease. In a retrospective study of 576 patients with known primary tumors sent to our institution for bone scintigraphy for the diagnosis of bone metastases, we evaluated 119 patients in whom both planar imaging and SPECT were obtained. The studies were graded for the probability of metastatic disease, and the number of spinal lesions was determined with and without SPECT. The influence of adding SPECT on the interpretation of the study was determined in terms of the reported probability of metastatic disease, the exclusion and confirmation of metastatic disease, the decisiveness of interpretation, and the number of spinal lesions. The addition of SPEeT resulted in a statistically significant change in the interpretation of studies, although the actual numbers of patients affected were relatively small. SPEeT resulted in a more decisive interpretation of bone scintigraphy. There was a significant increase in the number of spinal lesions detected after the addition of SPEeT. It was concluded that although the use of SPEeT is ideal, acceptable results could be achieved using planar imaging alone in this patient population. This is particularly relevant in the African context, where SPEeT is often unavailable or scarce and in great demand. / AFRIKAANSE OPSOMMING: Planare beenflikkergrafie is hoogs sensitief, maar moontlik nie sensitief genoeg om subtiele letsels in ingewikkelde beenstrukture soos die werwelkolom aan te toon nie. Akkurate anatomiese lokalisasie van letsels in die genoemde strukture is beperk wanneer slegs planare beelde gebruik word. Enkelfoton-uitstraling Rekenaartomografie (EFERT) lewer 'n hoër letsel kontras, wat 'n verbeterde sensitiwiteit vir die opsporing van subtiele letsels tot gevolg het. EFERT lei ook tot verbeterde letsel lokalisasie, wat dikwels van waarde is om onderskeid tussen benigne en maligne siekte in die werwelkolom te tref. Reeds met 'n aantal vorige studies is aangetoon dat die toevoeging van EFERT van die werwelkolom die waarde van beenflikkergrafie in die opsporing van beenmetastases beduidend verhoog bo dié van planare beelding alleenlik. Hierdie studies is egter nie in omstandighede eie aan Afrika gedoen nie, waar pasiënte kenmerkend met gevorderde siekte voordoen. In In terugskouende studie van 576 pasiënte met bekende primêre tumore, wat na ons instelling verwys is vir beenflikkergrafie om beenmetastases op te spoor, het ons 119 pasiënte, wat beide planare beelding en EFERT ondergaan het, ge-evalueer. Die studies is gegradeer volgens die waarskynlikheid vir metastatiese siekte, en die hoeveelheid werwelkolom letsels, met en sonder EFERT, is bepaal. Die invloed van EFERT op die vertolking van die studie is bepaal in terme van die waarskynlikheid van metastatiese siekte, die bevestiging en uitskakeling daarvan, die beslistheid van vertolking, en die hoeveelheid werwelkolom letsels. Die toevoeging van EFERT het tot 'n statisties beduidende verandering in die vertolking van studies gelei, alhoewel die werklike getal pasiënte wat hierdeur geraak is, relatief min was. EFERT het 'n meer besliste vertolking van beenflikkergrafie tot gevolg gehad. Daar was 'n beduidende toename in die hoeveelheid werwelkolom letsels wat opgespoor is na die toevoeging van EFERT. Daar is tot die slotsom gekom dat, alhoewel die gebruik van EFERT wenslik is, aanvaarbare resultate met slegs die gebruik van planare beelding in hierdie pasiënt bevolkingsgroep verkry kan word. Dit is veral van belang in Afrikaomstandighede, waar EFERT dikwels onbeskikbaar of skaars is, en ook in groot aanvraag is.

Thesis (M.S.)--University of Michigan, 2007. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 90-93).

Yuen, Wing Ki. / "June 2008." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 44-58). / Abstracts in English and Chinese, some text in appendix also in Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / Table of Contents --- p.5 / List of Tables --- p.8 / List of Figures --- p.9 / CHAPTER / Chapter 1. --- INTRODUCTION --- p.11 / Purpose of the Study --- p.12 / Hypotheses --- p.12 / Chapter 2. --- LITERATURE REVIEW --- p.13 / Chapter 3. --- METHODS --- p.17 / Study population --- p.17 / Aerobic Capacity of Apparently Healthy Hong Kong Population --- p.17 / Mr Os and Ms Os --- p.18 / Recruitment of subjects --- p.19 / Chapter (a) --- Relationship between age and vBMD for the Chinese population using pQCT --- p.19 / Chapter (b) --- Risk factors for vBMD in peripheral sites --- p.20 / Chapter (c) --- Performance of pQCT and DXA on fracture discrimination --- p.20 / Subject inclusion and exclusion criteria --- p.21 / Interview and questionnaire --- p.21 / Anthropometric measurements --- p.22 / Overall health and medication --- p.22 / Cigarette smoking and alcohol consumption --- p.23 / Grip strength --- p.23 / Physical activity --- p.23 / Walking speed --- p.23 / Assessment of fracture case --- p.24 / Incident fracture --- p.24 / Bone Mineral Measurements --- p.24 / pQCT measurement --- p.24 / DXA measurement --- p.25 / Statistical Analysis --- p.26 / Chapter 4. --- RESULTS --- p.27 / Chapter (a) --- Relationship between age and vBMD for the Chinese population using pQCT --- p.27 / Chapter (b) --- Risk factors for vBMD in peripheral sites --- p.29 / Lifestyle factors --- p.29 / Medical history and medications --- p.30 / Fracture history --- p.30 / Multivariate model --- p.30 / Chapter (c) --- Performance of pQCT and DXA on fracture discrimination --- p.31 / Chapter 5. --- DISCUSSION --- p.33 / Relationship between age and vBMD for the Chinese population using pQCT --- p.33 / Risk factors for vBMD in peripheral sites --- p.36 / Performance of pQCT and DXA on fracture discrimination --- p.39 / Limitations --- p.42 / Conclusion --- p.42 / Reference --- p.44 / Appendix --- p.84 / Chapter A) --- Informed Consent Form --- p.84 / Chapter B) --- Medical Record Consent Form --- p.86 / Chapter C) --- MrOs/ MsOs baseline Questionnaire --- p.87 / Chapter D) --- MrOs/ MsOs Physical Measurement Questionnaire --- p.111 / Chapter E) --- MrOs/ MsOs follow-up Questionnaire --- p.120

published_or_final_version / Medicine / Master / Doctor of Medicine