Thesis (M.S.)--University of Michigan, 1947. / eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--University of Michigan, 1977.

Magister Scientiae Dentium - MSc(Dent) / Teething, a common subject of discussion among nursing mothers has been held responsible for a variety of childhood ailments by both health professionals and parents. It appears to be a social construct coined by society to express the experience the child goes through during early days of childhood. Teething to the dental profession is the biological expression of tooth movement, in a predominantly axial direction, from the tooth's developmental position within the jaws to its emergence in the oral cavity. Several studies have reported both health professionals and parents to attribute local and systematic disturbances to the eruption of the primary dentition. The mothers experience and understanding of teeting have not been reported on. The aim of this study was therefore to explore the mothers experience of their child's teething. The objectives of the study were to determine what mothers understood by the term teething; to establish the signs and symptoms mothers associate with teething; to ascertain the treatment sought by mothers for their child's teething; to investigate how mothers in different setting understand and respond to teething. / South Africa

No description available.

Teething, a common subject of discussion among nursing mothers has been held responsible for a variety of childhood ailments by both health professionals and parents. It appears to be a social construct coined by society to express the experience the child goes through during early days of childhood. Teething to the dental profession is the biological expression of tooth movement, in a predominantly axial direction, from the tooth's developmental position within the jaws to its emergence in the oral cavity. Several studies have reported both health professionals and parents to attribute local and systematic disturbances to the eruption of the primary dentition. The mothers experience and understanding of teeting have not been reported on. The aim of this study was therefore to explore the mothers experience of their child's teething. The objectives of the study were to determine what mothers understood by the term teething / to establish the signs and symptoms mothers associate with teething / to ascertain the treatment sought by mothers for their child's teething / to investigate how mothers in different setting understand and respond to teething.

No description available.

No description available.

Phreatic and hydrothermal eruptions often occur with little or no warning representing a significant hazard within geothermal regions. These violent eruptions occur at a range of temperatures and pressures within varying rock types. A range of mechanisms including heating or decompression, allows hydrothermal/supercritical fluid to rapidly flash to steam, expanding and shattering the surrounding rock to produce an eruption, with no direct magmatic influence. These eruptions are highly variable resulting in the current wide ranging classification schemes, many of which are based on characteristics that are hard to observe and define. This has resulted in confusing nomenclature with many different terms used to describe the same eruptive phenomena. Here a new classification scheme is presented, based on the easily definable features of eruption size, trigger type (natural or anthropogenic) and geological setting (volcanic or hydrothermal). This ultimately produces a classification dividing the eruptions into either phreatic, where magma interacts with cold water but no juvenile material is erupted; or hydrothermal where eruption occurs from an already heated hydrothermal system. Examples are then provided for each classification type. Previous studies have focused exclusively on either physical characteristics of eruptions, small scale experimental modelling of trigger processes or mathematical modelling of various eruption characteristics. Here, a new experimental procedure has been developed to model phreatic fragmentation, based on shock tube experiments for magmatic fragmentation by Alidibirov and Dingwell (1996). Water saturated samples are fragmented from a combination of argon gas overpressure and steam flashing within vesicles. In this thesis, these experimental results have been integrated with the physical characteristics of porosity, permeability and mineralogy to create two new models of phreatic fragmentation. Firstly a generalised model to explain fragmentation processes and secondly a specific model describing the eruption forming Lake Okaro, within the Taupo Volcanic Zone of New Zealand. These models were developed with the overall aim to improve understanding of these eruption types, ultimately improving future hazard modelling. Experiments were performed on Rangitaiki ignimbrite, through which the Okaro eruption occurred. In order to evaluate alteration effects, both unaltered ignimbrite and hydrothermally altered ignimbrite samples were analysed. Experiments were performed at room temperature and 300°C with pressures from 4 to 15 MPa, to reflect likely geothermal conditions while also assessing the effect of liquid water on fragmentation. Results indicate that within these samples 5 to 8 MPa of decompression is required to trigger an eruption, fitting well with the previously identified trend between decompression and porosity for magmatic samples. The fragmentation front propagates through the sample at speeds ranging between 14 m/s to 42 m/s, increasing with higher applied pressures and higher sample porosity. Most importantly, grain size analysis from these experiments show a clear shift to smaller grain sizes when liquid water flashes to steam (independent of pressure or sample type), reflecting the greater energy involved with steam flashing. Previous grain size analysis of the Okaro breccia deposits have indicated that the highest weight percentage of fragments fall between -3.5 and 1.5 phi, with our experimentally produced fragments fitting right within this range at -0.5 to 1.0 phi. Here the first parameterisation of conditions for phreatic and hydrothermal eruptions is presented creating a general fragmentation model along with a case study on Lake Okaro. These models describe how eruptions occur, with stages from initial system priming and overpressure development through to the last stages of eruption and crater formation.

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.

Teething, a common subject of discussion among nursing mothers has been held responsible for a variety of childhood ailments by both health professionals and parents. It appears to be a social construct coined by society to express the experience the child goes through during early days of childhood. Teething to the dental profession is the biological expression of tooth movement, in a predominantly axial direction, from the tooth's developmental position within the jaws to its emergence in the oral cavity. Several studies have reported both health professionals and parents to attribute local and systematic disturbances to the eruption of the primary dentition. The mothers experience and understanding of teeting have not been reported on. The aim of this study was therefore to explore the mothers experience of their child's teething. The objectives of the study were to determine what mothers understood by the term teething / to establish the signs and symptoms mothers associate with teething / to ascertain the treatment sought by mothers for their child's teething / to investigate how mothers in different setting understand and respond to teething.