No description available.

<p>To compare the use of a piezoelectric with a standard surgical handpiece in third molar surgery. Thirty patients requiring removal of third molars were included in the study. Panoramic radiographs were used to assess the third molars. The patients were randomly subdivided and the split-mouth technique applied. In split-mouth design, divisions of the mouth, such as right (upper and lower) and left (upper and lower) quadrants constitute the experimental units, which are randomly assigned to two treatment groups. Each patient serves as his or her own control, which increases statistical efficiency (Siddiqi et al. 2010). Each side was operated with either a piezoelectric or a conventional handpiece. All aspects of preoperative care, general anaesthesia, surgery and postoperative care were standardized for the groups.</p>

Third molar (M3) impaction is commonly observed in dental practice. While the causes of impaction are still not clearly understood, they appear to be multifactorial. Currently, an insufficient amount of space in the jaw distal to the second molar - the retromolar (RM) region - is considered to be the most significant of these putative risk factors. However, M3 eruption is not always guaranteed by space availability in the RM region, and other factors such as delayed M3 mineralization, tooth crown size, and dental arch size are suspected to increase impaction risk. Because studies have traditionally focused on mandibular M3s and been limited to two-dimensional (2D) radiographs, this study is the first to investigate the causes of M3 impaction in both jaws, using 3D imaging, with precision and accuracy not previously possible using standard 2D dental imaging modalities. This study tests the hypothesis that not only a reduced amount of space in the RM region is observed when M3 impaction is present but also delayed M3 mineralization, larger molar and premolar crowns, and shorter dental arches. Research ethics permission (BIO#11-202) was obtained to use existing retrospective cone beam computed tomography (CBCT) images of over 500 patients aged 8 to 24 years taken and curated at the College of Dentistry, University of Saskatchewan. Anatomical landmarks were defined and a proprietary software package, Xoran-CAT (Imaging Sciences International, Philadelphia, USA) was used to measure RM regions, molar and premolar crowns, and dental arch dimensions, as well as to score M3 mineralization status. Results were assessed using independent sample t-tests. When M3 impaction was present, both short RM regions and delayed M3 mineralization occurred in both jaws, indicating that both of these are risk factors for impaction. In the presence of M3 impaction, narrower dental arches were observed only in the maxilla, while larger premolar and molar crowns were seen only in the mandible. The observation of these last risk factors in distinct jaws when M3 impaction was present, suggests that these are secondary factors in the determination of the M3 impaction condition, and that standards of M3 impaction differ between upper and lower jaws.

Magister Chirurgiae Dentium - MChD / To compare the use of a piezoelectric with a standard surgical handpiece in third molar surgery. Thirty patients requiring removal of third molars were included in the study. Panoramic radiographs were used to assess the third molars. The patients were randomly subdivided and the split-mouth technique applied. In split-mouth design, divisions of the mouth, such as right (upper and lower) and left (upper and lower) quadrants constitute the experimental units, which are randomly assigned to two treatment groups. Each patient serves as his or her own control, which increases statistical efficiency (Siddiqi et al. 2010). Each side was operated with either a piezoelectric or a conventional handpiece. All aspects of preoperative care, general anaesthesia, surgery and postoperative care were standardized for the groups. / South Africa

published_or_final_version / Paediatric Dentistry / Master / Master of Dental Surgery

Magister Chirurgiae Dentium (MChD) / There is a paucity of studies that make use of the alpha angle as a diagnostic tool to assist with the interceptive treatment, prognosis, treatment duration and surgical outcome of possible maxillary canine impaction in orthodontics. While the literature is replete with studies that utilise the sector method, the alpha angle is an alternative approach to assess the possible eruptive outcome of the unerupted canine. It has been reported that if the alpha angle is greater than 25°, there is the possibility of external root resorption. However, if the alpha angle is more than 31°, the prospect of canine eruption decreases even if the deciduous canine is extracted as an interceptive measure. The dental pantomograph has historically been used to predict canine eruption or possible impaction. The use of this method, however, is wrought with limitations. These limitations include magnification, distortion and blurred images. The use of cone-beam computed tomography has been advocated as a means to overcome these limitations.

abstract: In the nano-regime many materials exhibit properties that are quite different from their bulk counterparts. These nano-properties have been shown to be useful in a wide range of applications with nanomaterials being used for catalysts, in energy production, as protective coatings, and in medical treatment. While there is no shortage of exciting and novel applications, the world of nanomaterials suffers from a lack of large scale manufacturing techniques. The current methods and equipment used for manufacturing nanomaterials are generally slow, expensive, potentially dangerous, and material specific. The research and widespread use of nanomaterials has undoubtedly been hindered by this lack of appropriate tooling. This work details the effort to create a novel nanomaterial synthesis and deposition platform capable of operating at industrial level rates and reliability. The tool, referred to as Deppy, deposits material via hypersonic impaction, a two chamber process that takes advantage of compressible fluids operating in the choked flow regime to accelerate particles to up several thousand meters per second before they impact and stick to the substrate. This allows for the energetic separation of the synthesis and deposition processes while still behaving as a continuous flow reactor giving Deppy the unique ability to independently control the particle properties and the deposited film properties. While the ultimate goal is to design a tool capable of producing a broad range of nanomaterial films, this work will showcase Deppy's ability to produce silicon nano-particle films as a proof of concept. By adjusting parameters in the upstream chamber the particle composition was varied from completely amorphous to highly crystalline as confirmed by Raman spectroscopy. By adjusting parameters in the downstream chamber significant variation of the film's density was achieved. Further it was shown that the system is capable of making these adjustments in each chamber without affecting the operation of the other. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2015

The eddy impaction ash deposition model derived and validated in this document predicts eddy impaction rates as a function of turbulence intensity, boundary layer thickness, and gas velocity. The experimental apparatus introduces small particles (200 nm, 25 µm, and 500 µm diameter) into a gas stream flowing through a horizontal pipe (Re 2,300-8,000). The particles deposit on the pipe wall and the total mass of impacted particles provides a measure of collection efficiency. Experimental results indicate deposition velocity increases with Reynolds number, consistent with eddy impaction theory and based on increased turbulent energy. Eddy impaction also increases with particle size at fixed Reynolds number, again consistent with theory.

Objectives: To investigate differences in the modulus of elasticity, tensile strength, and load at breakage for elastic thread alone and elastic thread with gold chain in combination used in force application of palatally impacted and exposed maxillary canines. Methods: Two groups with n=6 in each were tested. A circular portion of elastic thread was cut, tied and measured to the nearest hundredth of a millimeter and recorded. Five links of a gold chain were cut and an elastic thread was tied to the fifth link opposite the bondable eyelet. The length of the elastic thread and the total apparatus was measured to the hundredth of a millimeter and recorded. An Instron with a ramp speed of 100 mm/min was used for all testing. Results: The addition of the gold chain, as compared to the elastic thread alone, increased the modulus from 8.8 MPa (SD 3.7) to 17.0 MPa (SD 5.03), (p&lt; 0.04) and significantly decreased the maximum tensile stress at breakage from 92.1N (SD 5.0) to 84.1N (SD 1.6), (p&lt;0.004) and the tensile stress at maximum load from 107.8 N (SD 6.7) to 93.8N (SD 4.8), (p&lt;0.002). The stress-strain curve for both groups demonstrated an initial linear behavior followed by non-linear behavior, partially obeying Hooke’s Law, due to the inherent nature of the elastic thread. The addition of the gold chain introduced a rigid element by reducing the of length of the elastic thread by one-half, altering the properties of the assembly. Conclusions: The modulus of elasticity (stiffness) increases and the toughness and resiliency decreases when a gold chain is added to the assembly and compared to elastic thread alone. This could indicate that in the gold chain group, more initial force/strain is delivered to the tooth and there is less stress relaxation over time due to the decrease in the amount of elastic thread. Therefore, the elastic thread alone delivers a more constant and continuous force to the tooth. The use of elastic thread alone may provide a biomechanically more efficient approach to orthodontic movement of impacted and open exposed teeth. / Oral Biology

Student Number : 9000040F - M Dentistry research report - Faculty of Health Sciences / This study assessed the sagittal soft-tissue changes of the lower lip and chin area in 22 patients subsequent to mandibular autorotation following surgical vertical impaction of the maxilla. A subgroup of six patients in addition had undergone advancement genioplasty procedures. Lateral cephalometric radiographs were taken immediately prior to surgery and on average 15 months following surgery. Sixteen cephalometric landmarks were identified on each radiograph and these were digitized using a Kontron Videoplan Image Analysis System to enable differences reflecting changes to be assessed. The comparison between those cases that had had maxillary elevation only and the six cases that had received additional advancement genioplasty procedures revealed statistically significant differences in relation to the proportional changes in the chin area. Therefore, when studying the soft-tissue chin changes following mandibular autorotation, these six patients were excluded from the sample. It was found that there was no significant difference in the lower lip response between the two groups and therefore when studying the lower lip changes, the two groups could be pooled. The soft-tissue changes in the chin area showed statistically and clinically significant correlations. In the horizontal plane, a ratio of 0.9:1 was found for the changes between sulcus inferior and point B, between soft-tissue pogonion and hard-tissue pogonion, and between soft-tissue gnathion and hard-tissue gnathion. In the vertical dimension, soft-tissue gnathion followed hard-tissue gnathion in a ratio of 0.9:1, whereas soft-tissue menton followed hardtissue menton in a ratio of 1:1. In the study of the lower lip response, a significant correlation with a ratio of 1:1 existed for the horizontal change in the lower lip as measured at labrale inferius relative to both lower incisor tip and lower incisor anterius. In the vertical dimension, stomion inferius followed lower incisor anterius in a ratio of 1.3:1, while labrale inferius followed lower incisor anterius in a ratio of 1.5:1. Multiple regression analyses revealed that presurgical tissue thickness exerted no influence upon the strength of the correlations between changes expressed at corresponding soft- and hard-tissue landmarks located in the lower lip and soft-tissue chin area. Based on the findings of this study, it is suggested that the soft-tissue to hard-tissue ratios may be applied to prediction tracings with enhanced confidence. As a result, the tracings will reflect a more accurate prediction of the lower lip and soft-tissue chin positions following autorotation of the mandible.