Magister Scientiae Dentium - MSc(Dent) / A public orthodontic system generally is designed to prioritize patients so that those who have the greatest need receive treatment. The aim of this study was to compare the subjective perceptions of the occlusal appearance of 11 to 12 year-old schoolchildren of Nairobi with the modified Aesthetic Component (AC) scale of the Index of Orthodontic Treatment Need (IOTN). The objectives were to assess the children's perception of their occlusal appearance, categorise the occlusal appearance using the AC scale, by both the children and researcher; and to compare the children's' perception and the AC of the IOTN. Satisfaction with appearance of teeth and occlusion as well as peer comparison was investigated. The treatment need and demand was assessed using the modified AC photographs of the IOTN. Altogether, 488 school children (249 girls and 239 boys) assessed their perception of the anterior teeth using a Verbal Descriptor Scale (VDS) and a Visual Analog Scale (VAS) questionnaire. The researcher examined the anterior teeth of the participants and categorised them using the AC of the IOTN. The following results were reported: about two-thirds of the respondents were satisfied with the appearance of their teeth, with the gender difference being statistically significant. About 35% were dissatisfied or very dissatisfied, but reasons for it varied. More than half of the respondents rated their teeth as better than those of their peers and three-quarters were satisfied with their occlusion, the two responses elicited no gender difference. Treatment need was assessed by use of the AC indicated that there was a moderate agreement between researcher and respondents’ in treatment need assessment. The researcher found 36.3% needed treatment against self-perceived need of 30.9%. One-third of the respondents determined by the researcher to 'need treatment', felt 'no need'. There was no statistical gender difference in perceived need for treatment. The selection of ranked photographs of the AC by both researcher and respondents demonstrated skewed distributions towards the 'low ranked' or attractive end of the ranking order irrespective of the state of occlusion. Statistical comparison of the two methods used, namely the VDS and VAS, indicated that the responses were significantly different. Therefore it is suggested that any treatment priority assessment should take perceptions of occlusal appearance. into consideration.

Nos tratamentos ortodônticos, fios de diferentes ligas metálicas são utilizados nas etapas de alinhamento, nivelamento, correção da posição molar, fechamento espacial, acabamento e retenção. Com relação às duas últimas, responsáveis pelo posicionamento adequado dos dentes superiores sobre os inferiores, a preparação requer um fio que favoreça o torque de incisão, ou seja, que apresente grande resistência e rigidez associadas à ativação de pequeno alcance. Para este fim, os fios de aços inoxidáveis austeníticos retangulares são os preferidos em razão do módulo de elasticidade elevado e boa resistência à corrosão no meio bucal. Quanto à geometria retangular, o processo de fabricação requer desenvolvimento tecnológico adequado para a produção em escala industrial de fios com as características geométricas e propriedades mecânicas para melhor adequação às necessidades de uso. Com o objetivo de se produzir fios com tais características, foi desenvolvido um laminador para a fabricação de fios retangulares com a intuito de se dispor de uma alternativa de menor custo ao processo de produção por trefilação, de custo elevado, devido a complexidade das matrizes. Além da fabricação do laminador, foram avaliados os aspectos tecnológicos que envolveram os efeitos da deformação nas propriedades mecânicas dos fios, por meio de medidas de microdurezas e ensaios em tração e de flexão. Nos testes realizados, os fios apresentaram geometria, acabamento superficial e propriedades mecânicas adequadas à sua utilização em tratamentos ortodônticos. / In orthodontic treatments, wires of different metallic alloys are used for alignment, leveling, correction of the molar position, space closing, finish and retention. With respect to finish and retention, these wires are responsible for adequate positioning of the upper teeth on the lower teeth. Wires that are subjected to incisor torque require high resistance and stiffness. For this, wires of rectangular austenitic stainless steel are used due to high modulus of elasticity and good corrosion resistance in the oral environment. Because of the rectangular geometry, wire production requires process development suitable for industrial scale manufacture with geometric characteristics and mechanical properties better adapted to the use conditions. To obtain wires with such characteristics, a rolling mill was developed for the production of rectangular wires by a rolling process with the objective of reducing cost of the cold drawing process that is currently used, which utilize complex and expensive wiredrawing dies. In addition to the rolling process itself, wire deformation, microhardness, tension and bend tests were also performed. In these tests, wire geometry, surface finish and mechanical properties were successfully adapted for use in orthodontic treatments.

Magister Scientiae Dentium - MSc(Dent) / The research is aimed at investigating and finding alternatives to the physical necessity of producing and storing plaster casts or stone models of the tissues of the mouth. The quest for time and space is universal and the successful management of both results in stress free, financially stable and uncluttered work circumstances. Study models do playa very important role in diagnostics and treatment planning as well as communicating final results in Dentistry, especially in Orthodontic practice. Conventional study models are bulky, fragile, and expensive diagnostic tools produced from impressions taken of the patient's mouth and cast in plaster or stone. The storage of these records creates major space problems, and recalling or retrieving models at some later stage also causes logistical problems. Ideally, the tissues of the mouth could be scanned and from this a 3-D image produced on screen, which could later be milled (machining process of reproducing, explained in Appendix B) if necessary. Three dimensionally accurate, visually pleasing, reproducible, measurable and retrievable records, would be the solution. Computerizing dental records has already revolutionized the industry in the fields of Radiology and written patient data. This information is available at the click of a mouse, and integrated diagnostic tools can be displayed on screen. A thorough investigation of all methods of capturing dental data and 3D images from previously researched and publicized studies was conducted before attempting the latest technology. The final project involved: 1. requesting an introductory and explanatory demonstration on the scanning possibilities in South Africa 2. organizing and attending a demonstration of the laser and contact scanner on study models and impressions. 3. undergoing training in the use of a contact scanner. Computerizing of these results and comparing data derived from analyzing both study models and impressions, manually and digitally. 4. researching and collecting of data with engineering professionals, to establish the validity and viability of this method ( aiming to use uncomplicated, widely accepted and thoroughly applicable basic criteria in all experiments.) 5. evaluation of data statistically by a statistician. Discussion: Digitizing and computerizing of images derived from scanning the models or impressions offers the most attractive alternative for record keeping. Laser scanning disappointed in general due to the relative unavailability in South Africa, the expensive nature of the service elsewhere and limiting factors due to the sensitivity of the laser beam. It is the most promising alternative in future research, because of improved accuracy, higher speed of scanning, uniformity and reproducibility. Contact scanning proved to be available, reliable and adjustable. In most applications, the best results in terms of accuracy and quality of surface finish are obtained using contact scanning. The disadvantage of this method is the time factor and therefore it becomes expensive and economically not viable. The direct scanning of impressions, albeit with laser or contact scanning, remains a scientific and clinical viable option. Conclusion: Digital imaging is still a young technology and many aspects are not yet completely explored. It is a promising technology and its significance is increasing because it opens the door to diagnostic information. Another important development is that the software for digital imaging will become more integrated with other computerized dental applications in the dental office, enabling patient data between different and remote practices to be exchanged more easily. Further progress is not limited by a lack of available image processing tools but rather by our restricted understanding of the various components of diagnostic imaging in dentistry. A Bioengineering exhibition mounted by the University of Munich during a December 2000 conference, displayed a specially adapted CT Scanner that could scan information directly from the mouth. This leads to more possibilities of deriving images without impressions or study casts.

Magister Chirurgiae Dentium (MChD) / Cephalometric norms for the soft-tissue profile presently utilized in this country, are based almost entirely on North American Caucasian and Negroid studies. Orthodontists use these standards as a guide in the treatment of all sections of the South African population. Various studies have conclusively shown that the soft-tissue profile differs both racially, and from country to country. In recent years the number of patients presenting for orthodontic treatment at the University of the Western Cape has increased significantly. The need has therefore arisen for the establishment of soft-tissue profile trends in the Western Cape area.

Magister Chirurgiae Dentium (MChD) / Skeletal age assessment is not only an important aspect in orthodontic treatment planning, but is also widely used in forensic medicine and physi cal anthropology. Vari aus studi es have shown that chronological age may be at variance with an individual's biologic age. Current research would seem to indicate that the hand-wrist radiograph provides the most accurate method of assessing skeletal age for diagnostic purposes. In recent years the number of patients presenting with malocclusions of a skeletal nature at the University of the Western Cape has increased si gnifi cantly. If it i s accepted that treatment of jaw di screpancies associated with malocclusion is dependent on a large component of dentofacial orthopedics, then by implication it is necessary that a substanti al amount of faci al growth remai ns. The need has therefore arisen for the establishment of skeletal maturation trends in the Western Cape. Skeletal maturity was assessed from hand-wrist radiographs in a sample of 318 Western Cape children aged 6 to 16 years for both sexes, utilising the bone specific Tanner-Whitehouse TW-2 scoring system. Data obtai ned from the present study showed a marked difference in skel etal maturati on trends between femal es of the Western Cape to that of the British norm, while the males showed less divergence. Further, these findings show that in both sexes the epiphyseal bones matured in advance of the TW-standard. Carpal maturation, however, was delayed in the male when compared to the British standard, while that of the female conformed to that of the British standard.

Magister Scientiae Dentium - MSc(Dent) / These laws were first published in Latin,in 1687.The first law may be literally translated thus, Every body continues in its state of reat or of uniform motion in a straight line ,unless it is compelled to change that state by impressed force. This meano that if a body is at rest it will remain so unless some force acts on it,if in motion ,the velocity of motion must continue uniform unless some force acts to increase it or diminish it. Also the direction of motioA mast continue unchanged and therefom rectilinear unless some force causes it to be diverted. This law therefore supplies us with a definition of force; Force is that which produces or tends to produce, motion 0.' change of motion. Newton's second law of motion may be translated as follows:- Newton's second law of motion may be translated as follows:- The change of motion (produced)is proportional to the impressed force producing it,and pursues the direction in which that force is impressed. This law leads to a method of measuring forces. If we change the velocity with which a mass is moving,we also change its momentum. Change in momentum will serve to measure force.lt seems obvious that whatever change in momentum is produced by a force, twice the force will produce twice the change ,etc.i.e. the change is directly proportional to the force. For a given mass,m,change of momentum ,mv,means change of velocity;the change of velocity per unit time is aceeleration,a;the change in momentum per unit time is therefore malf we employ absolute units (poundals or dynes)this can be shown as; Newton's third law of motion states that 'to every action there is an equaI and opposite reaction'.This law recognises the dual aspect of forces It a tooth is pushed by a finger spring ,the spring is also pushed by the tooth,and an eqpal counter force acts towards the spring unti1 the biology of the system intervenes. This dual stress is called pressure. Retracting incisors against posterior segments it is apparent that the reaction of the posterior segments must be equal and opposite to the incisors.In this case the two forces act away trom each other,and tG this dual stress we give the name tension.

Objectives: To test that the speed of tooth translation is not affected by stress magnitude and growth status. Setting and Sample Population: Advanced Education Orthodontic clinics at the Universities of Nebraska Medical Center and Missouri-Kansas City. Forty-six consenting subjects with orthodontic treatment plans involving maxillary first premolar extractions. Materials and Methods: This randomized split-mouth study used segmental mechanics with definitive posterior anchorage and individual vertical-loop maxillary canine retraction appliances and measured three-dimensional tooth movements. Height and cephalometric superimposition changes determined growing (G) and non-growing (NG) subjects. Subjects were appointed for 9-11 visits over 84 days for maxillary dental impressions to measure three-dimensional tooth movement and to ensure retraction forces were continuously applied via calibrated nitinol coil springs. Springs were custom selected to apply two different stresses of 4, 13, 26, 52 or 78 kPa to maxillary canines in each subject. Statistical analyses (α=0.050) included ANOVA, effect size (partial η2) and Tukey's Honest Significant Difference (HSD) and two-group t tests. Results: Distolateral translation speeds were 0.034±0.015, 0.047±0.019, 0.066±0.025, 0.068±0.016 and 0.079±0.030 mm/d for 4, 13, 26, 52 and 78 kPa, respectively. Stress significantly affected speed and partial η2=0.376. Overall, more distopalatal rotation was shown by teeth moved by 78 kPa (18.03±9.50º) compared to other stresses (3.86±6.83º), and speeds were significantly higher (P=.001) in G (0.062±0.026 mm/d) than NG subjects (0.041±0.019 mm/d). Conclusions: Stress magnitude and growth status significantly affected the speed of tooth translation. Optimal applied stresses were 26-52 kPa, and overall speeds were 1.5-fold faster in G compared to NG subjects.

Introduction: Orthodontics has clinical benefits, however, the psychosocial outcomes are not well understood. These soft benefits are often classified as aesthetic, functional, and psychosocial, however, there is limited work understanding these outcomes as reported directly from the patient. By better understanding the patient’s perspectives, we can continually refine our clinical model to be patient-centric and more appropriately manage the patient’s expectations and experiences. Materials and Methods: This is a cross-sectional qualitative study of 20 parents of 24 children ages 8-11 years. Participants were remotely interviewed using a semi-structured chronologically based line of questioning to elucidate their perceived outcomes of early orthodontic treatment or phase one. A content thematic analysis using a framework approach was used to analyze the resulting data. Results: The thematic analysis uncovered four major themes and associated subthemes as follows (1) dental health including functional changes, aesthetic improvement, and improved cleansability; (2) opportunity cost: meaning harnessing growth for lasting change, avoidance of future orthodontic treatment, avoidance of future dental treatment, and supervision of growth; (3) social outcomes: encompassing external perception and acceptance, self-perception, parental perception, and reduced dental anxiety; and (4) behavioral changes: including the correction of bad habits, development of good oral hygiene, and an increase in responsibility of the patient. Conclusions:This study highlights the depth of psychosocial benefit perceived by patients undergoing early orthodontic treatment, with the main outcome being functional improvement, followed by an advantage to treatment at a young age, and an improvement in aesthetics. Patients did not recognize an increase in self-perception which is contrary to outcomes previously found in other age groups.

Indiana University-Purdue University Indianapolis (IUPUI) / Microabrasion with PREMA Compound (Premier Dental Product Co., King of Prussia, Penn.) has been advocated for the removal of superficial enamel stains. This procedure eliminates stains by removing a microscopic layer of enamel. The objective of this study was to determine whether the use of PREMA microabrasion prior to orthodontic bonding affects the tensile bond strength of an adhesive precoated stainless steel orthodontic bracket. Sixty noncarious extracted human premolar teeth were randomly divided into three groups of 20 and stored in 3-percent buffered formalin solution. Group I was a control group that was etched and bonded in the usual manner. Group II received PREMA Compound microabrasion immediately prior to bonding. Group III received PREMA microabrasion followed by a six-week storage period prior to bonding. After bonding, specimens were thermocycled and stored in distilled water at 37 °C for 14 days. The specimens were then loaded to failure in the tensile mode of an Instron testing machine (Instron Corp., Canton, Mass.). A stress-breaking apparatus was utilized to minimize all forces other than tensile. The data was statistically analyzed using one-way analysis of variance at the 0.05 level. No statistically significant differences were found among the three groups. From these results it was concluded that microabrasion with PREMA did not affect bond strength. Enamel microabrasion can be provided prior to orthodontic treatment without any detriment to bracket bond strength.

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