It is common practice to remove impacted mandibular third molars due to pathology associated with these impactions. Alternatively, impactions can be treated conservatively through a closely guarded follow-up regiment. However, many symptoms associated with impacted third molars may be prevented by elective removal of potentially problematic teeth. To determine the risk of developing pathology associated with impacted mandibular third molars, a ransom sample of 200 pantomographs were analyzed displaying 324 impactions from patients who presented for treatment at the Maxillo-Facial and Oral Surgery Department, Faculty of Dentistry, University of the Western Cape.

It is common practice to remove impacted mandibular third molars due to pathology associated with these impactions. Alternatively, impactions can be treated conservatively through a closely guarded follow-up regiment. However, many symptoms associated with impacted third molars may be prevented by elective removal of potentially problematic teeth. To determine the risk of developing pathology associated with impacted mandibular third molars, a ransom sample of 200 pantomographs were analyzed displaying 324 impactions from patients who presented for treatment at the Maxillo-Facial and Oral Surgery Department, Faculty of Dentistry, University of the Western Cape.

Magister Scientiae Dentium - MSc(Dent) / It is common practice to remove impacted mandibular third molars due to pathology associated with these impactions. Alternatively, impactions can be treated conservatively through a closely guarded follow-up regiment. However, many symptoms associated with impacted third molars may be prevented by elective removal of potentially problematic teeth. To determine the risk of developing pathology associated with impacted mandibular third molars, a ransom sample of 200 pantomographs were analyzed displaying 324 impactions from patients who presented for treatment at the Maxillo-Facial and Oral Surgery Department, Faculty of Dentistry, University of the Western Cape. / South Africa

Abstract CROWN SIZE COMPARISONS IN PATIENTS WITH PALATALLY DISPLACED CANINES By Joseph L. Eliason, D.D.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University. Virginia Commonwealth University, 2015 Thesis Director: Steven J. Lindauer, D.M.D., M.Dent.Sc. Professor and Chair, Department of Orthodontics There has been significant debate over the past decades regarding the etiology of palatally displaced canines. Theorized risk factors include agenesis or malformation of the lateral incisors, incisor retroclination, transverse deficiency, or genetic predisposition. The purpose of this study is to compare the linear and volumetric measurements of canines and lateral incisors to determine how tooth size relates to canine impaction. Cone-beam CT images for 40 patients with unilateral palatally displaced canines were utilized to measure the linear dimensions and total crown volume of canines and lateral incisors and to compare those teeth on the impaction side with their isomers on the non-impaction side. Results showed that unilateral palatally impacted maxillary canine crowns were slightly, but statistically significantly wider and larger in volume than their non-impacted isomers. Lateral incisor crowns adjacent to impacted canines were significantly shorter than those adjacent to non-impacted canines.

In the event of a hypothetical nuclear reactor accident, the combination of plant design, operator training, and safety procedures result in low level risks to the general public; however, an additional offsite consequence mitigation system has the poten- tial to substantially decrease the amount of radioactive material that could reach a population zone in a postulated accident scenario. An experimental and numerical investigation of airborne particulate scavenging by water sprays was conducted as part of a consequence mitigation study. Previous researchers have experimentally studied the removal of aerosols by sprays, but only in a confined region. The ex- periment conducted in this research used an expansive region where sprays could significantly affect the flow fields in the spray region. Experimentation showed an expected trend of higher particle collection efficien- cies with increased residency time within the spray region, with the highest average overall collection efficiency found to be 70.6+/-3.2% at an air flow rate of 0.53 m/s and a water flow rate of 0.84 gpm. This general trend is expected because a longer resi- dency time leads to an increased probability of particle-drop interaction. Collection efficiencies were also found to increase with increased particle number density. The numerical investigation was done using a deterministic method and a Monte Carlo method. Each model shows promise based on theoretical limitations of drop size for the experimental conditions. The theory demonstrates that particle-drop relative velocity as well as the sizes significantly affect collection efficiency. An alternative study was conducted to determine the collection efficiency of non-wettable particles since the dust used in the experiment is hydrophobic. Computational Fluid Dynam- ics (CFD) models were also performed to determine the flow fields that developed within the experiment spray region and substantiate differences in the experimental and numerical models.

Failure of a primary hip arthroplasty is often caused by osteolysis which compromises the patient’s periprosthetic bone stock. Impaction allografting involves the use of morselized allograft bone and cement to stabilize the implant and restore this periprosthetic bone stock. Although clinical results of impaction allografting are favourable, regions of necrotic bone graft have been shown to exist for many years post-operatively and may ultimately lead to implant failure. Previous laboratory research has identified a correlation between mechanical stimuli and bone growth; therefore, the purpose of this study was to develop an in vivo device that would enable the investigation of the effect of mechanical load on bone graft incorporation in impacted allograft hip prostheses. An actuator was developed with a finite volume to enable its subcutaneous implantation along the tibia (20mm x 10mm x 10mm) and spine (35mm x 25mm x 15mm) in a rat bone chamber model. The actuator was designed to deliver a dynamic, (1Hz), compressive, (-6N), load that was controlled telemetrically throughout a 6-week long in vivo study. Independent validations of the mechanical actuator and the electrical control system were performed prior to an electromechanical validation of the integrated system. The responsiveness, quantity and magnitude of the load were investigated. The mechanical actuator was motor-driven and the electrical control system was based on radio frequency signal transmission. The electromechanical actuator conformed to the volumetric restrictions of the rat bone chamber model (tibia: 13mm x 17mm x 10mm; spine: 35mm x 30mm x 11mm). A wide range of operating frequencies (0.5 to 3.0 ± 0.05Hz) was achieved and a telemetrically controlled load was produced for 20 seconds per day throughout a simulated 6 week in vivo study. Due to inefficiencies of the mechanical actuator and voltage limitations of the control system, the magnitude of the compressive load produced by the actuator (-1.67 ± 0.10N) was less than specified by the design criteria. Future work to optimize the actuator design and fabrication is warranted in order to increase the maximum load magnitude; however, the current design provides a novel means to begin the investigation of the role of mechanical load on bone graft incorporation in impaction allografting.

Failure of a primary hip arthroplasty is often caused by osteolysis which compromises the patient’s periprosthetic bone stock. Impaction allografting involves the use of morselized allograft bone and cement to stabilize the implant and restore this periprosthetic bone stock. Although clinical results of impaction allografting are favourable, regions of necrotic bone graft have been shown to exist for many years post-operatively and may ultimately lead to implant failure. Previous laboratory research has identified a correlation between mechanical stimuli and bone growth; therefore, the purpose of this study was to develop an in vivo device that would enable the investigation of the effect of mechanical load on bone graft incorporation in impacted allograft hip prostheses. An actuator was developed with a finite volume to enable its subcutaneous implantation along the tibia (20mm x 10mm x 10mm) and spine (35mm x 25mm x 15mm) in a rat bone chamber model. The actuator was designed to deliver a dynamic, (1Hz), compressive, (-6N), load that was controlled telemetrically throughout a 6-week long in vivo study. Independent validations of the mechanical actuator and the electrical control system were performed prior to an electromechanical validation of the integrated system. The responsiveness, quantity and magnitude of the load were investigated. The mechanical actuator was motor-driven and the electrical control system was based on radio frequency signal transmission. The electromechanical actuator conformed to the volumetric restrictions of the rat bone chamber model (tibia: 13mm x 17mm x 10mm; spine: 35mm x 30mm x 11mm). A wide range of operating frequencies (0.5 to 3.0 ± 0.05Hz) was achieved and a telemetrically controlled load was produced for 20 seconds per day throughout a simulated 6 week in vivo study. Due to inefficiencies of the mechanical actuator and voltage limitations of the control system, the magnitude of the compressive load produced by the actuator (-1.67 ± 0.10N) was less than specified by the design criteria. Future work to optimize the actuator design and fabrication is warranted in order to increase the maximum load magnitude; however, the current design provides a novel means to begin the investigation of the role of mechanical load on bone graft incorporation in impaction allografting.

Failure of a primary hip arthroplasty is often caused by osteolysis which compromises the patient’s periprosthetic bone stock. Impaction allografting involves the use of morselized allograft bone and cement to stabilize the implant and restore this periprosthetic bone stock. Although clinical results of impaction allografting are favourable, regions of necrotic bone graft have been shown to exist for many years post-operatively and may ultimately lead to implant failure. Previous laboratory research has identified a correlation between mechanical stimuli and bone growth; therefore, the purpose of this study was to develop an in vivo device that would enable the investigation of the effect of mechanical load on bone graft incorporation in impacted allograft hip prostheses. An actuator was developed with a finite volume to enable its subcutaneous implantation along the tibia (20mm x 10mm x 10mm) and spine (35mm x 25mm x 15mm) in a rat bone chamber model. The actuator was designed to deliver a dynamic, (1Hz), compressive, (-6N), load that was controlled telemetrically throughout a 6-week long in vivo study. Independent validations of the mechanical actuator and the electrical control system were performed prior to an electromechanical validation of the integrated system. The responsiveness, quantity and magnitude of the load were investigated. The mechanical actuator was motor-driven and the electrical control system was based on radio frequency signal transmission. The electromechanical actuator conformed to the volumetric restrictions of the rat bone chamber model (tibia: 13mm x 17mm x 10mm; spine: 35mm x 30mm x 11mm). A wide range of operating frequencies (0.5 to 3.0 ± 0.05Hz) was achieved and a telemetrically controlled load was produced for 20 seconds per day throughout a simulated 6 week in vivo study. Due to inefficiencies of the mechanical actuator and voltage limitations of the control system, the magnitude of the compressive load produced by the actuator (-1.67 ± 0.10N) was less than specified by the design criteria. Future work to optimize the actuator design and fabrication is warranted in order to increase the maximum load magnitude; however, the current design provides a novel means to begin the investigation of the role of mechanical load on bone graft incorporation in impaction allografting. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

published_or_final_version / Dentistry / Master / Master of Dental Surgery

<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>