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Facial alveolar bone wall width: a cone beam computed tomography (CBCT) study in AsiansZekry, Ahmed Khaled Ahmed Abdin. January 2012 (has links)
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
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Preparation of curved root canals with different nickel-titanium rotary systems: three-dimensional comparisonusing micro-computed tomographyChiu, Mei-ling, Bonnie., 趙美玲. January 2003 (has links)
published_or_final_version / Dentistry / Master / Master of Dental Surgery
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Tuned aperture computed tomography (TACT) : an investigation on the factors associated with its image quality for caries detectionDe Abreu, Murillo Jose Nunes 03 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The purpose of this investigation was to explore the multiple variables involved in TACT®
image generation in an attempt to optimize this imaging modality for the diagnostic task of
primary dental caries detection. The work is divided in seven phases in which the variables are
evaluated individually. Teeth from the study samples were mounted in dental stone and imaged
with a solid state digital radiography sensor. As a requisite of TACT® imaging, multiple images
of the teeth were acquired from different projection angles. These resulting basis images were
then used to generate TACT® slices. Variables tested in the investigation included the number of
iterative restorations to which the slices were submitted, the number of basis images, the angle
formed between the basis images, the two- and three-dimensional distribution of the basis
projections in space, and the method through which the slices were reconstructed. For all phases,
observers were asked to assess the presence or absence of primary caries in the teeth imaged
using the TACT® slices treated with the different variables. Finally, to determine whether the
best combination of variables produced a significant improvement in diagnostic performance, a
comparison with conventional digital radiography images was carried out. No statistically
significant differences were found in caries detection between TACT® slices submitted to
different numbers of iterative restorations, reconstructed from basis images bearing different
angular disparities, spatial distributions (in both two and three dimensions), or through different
reconstruction methods. A statistically significant difference was detected between TACT® slices
reconstructed from different numbers of basis projections. The final comparison showed that
TACT® was not statistically superior to conventional digital radiography for the task of caries
detection. The results of this investigation suggest that, although TACT® has been shown to be
useful in many tasks performed in dentistry, its application in caries detection is not essential
inasmuch as there are modalities that are simpler, more practical, less expensive, and that submit
the patient to smaller radiation doses.
Keywords: TACT, tomosynthesis, image reconstruction, digital radiography, caries detection,
ROC analysis, analysis of variance / AFRIKAANSE OPSOMMING: Die doel van hierdie proefskrif was om die veelvuldige veranderlikes wat betrokke is by
gewysigde spleet rekenaartomografie (Tuned Aperture Computed Tomography (TACT)) te
ondersoek in 'n poging om die beeldingsmodaliteit te optimaliseer in die diagnostiese opsporing
van primere karies. Die proefskrif bestaan uit 'n ekstensiewe literatuur oorsig en word in 7
fases aangebied waarin die veranderlikes individueel geevalueer word. Tande is in gips ingebed
en radiografiese opnames is gemaak met behulp van 'n digitale radiografiese sensor. As 'n
voorvereiste vir TACT beelding is veelvuldige beelde uit verskillende projeksiehoeke van die
tande gemaak. Die resulterende basisbeelde is dan gebruik om TACT snitte te produseer.
Veranderlikes wat in die proefskrif getoets is, sluit die volgende in: 'n aantal herhalende
herstellings waaraan die snitte blootgestel is, die aantal basisbeelde, die hoek gevorm tussen die
basisbeelde, die 2 en 3 dimensionele verspeiding van die basis projeksies in die ruimte en die
metodes waardeur die snitte gerekonstrueer is. In aIle fases is waarnemers gevra om die
teenwoordigheid of afwesigheid van primere karies te evalueer wat met TACT afgeneem is met
in ag neming van die verskillende veranderlikes. Ten slotte, om te bepaal of die beste
kombinasie van veranderlikes 'n aansienlike verbetering in diagnostiese prestasies sou meebring,
is 'n vergelyking met konvensionele digitale radiografiese beelding uitgevoer. Geen statistiese
beduidende verskille is waargeneem in die opsporing van karies tussen TACT snitte wat
blootgestel is aan verskillende aantal herhalende herstellings, rekonstruksie van basis beelding
met verskillende hoek veranderinge, ruimtelike verspreiding (beide 2 en 3 dimensioneel) of deur
verskillende rekonstruksie metodes nie. 'n Statistiese beduidende verskil is waargeneem tussen
TACT snitte wat van 'n verskeidenheid basis projeksies gerekonstrueer is. Die finale
vergelyking het aangetoon dat TACT nie statisties beter is as konvensionele radiografie in die
opsporing van karies nie.
Die resultate van hierdie proefskrif het getoon dat alhoewel TACT bruikbaar is in vele
prosedures wat in die tandheelkunde uitgevoer word, is die toepassing daarvan in die diagnose
van karies nie noodsaaklik nie, omdat daar in die tandheelkunde modaliteite beskikbaar is, wat
meer eenvoudig, meer prakties en goedkoper is, met 'n laer stralingsdosis vir die pasient.
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