No description available.

The aim of this study was to investigate the prevalence, etiology and types of injuries to permanent incisors among schoolchildren aged 10-14 years from Maseru, Lesotho. Upper and lower permanent incisors were examined for dental injuries.

Eighty normal cheek teeth and 26 normal incisors extracted from 14 donkeys (median age 19 years) at post mortem were anatomically examined including grossly and by computerised axial tomography (CAT) imaging. Decalcified histology was performed on 54 sections from 18 teeth (8 donkeys), undeclacified histology on 16 sections from 7 donkeys and scanning electron microscopy on 10 sections from 10 teeth (3 donkeys). The dental formulae and tooth number was found to be the same as in horses with a higher prevalence (17 %) of canine teeth in female donkeys. A decrease in tooth length, pulp horn length and pulp horn width with age was illustrated, as was an increase in occlusal secondary dentine depth with age, although not all these age changes were statistically significant. Normal histological and ultrastructural features of donkey teeth were identified and found to be similar to equine findings. Enamel was found to be thicker buccally in both maxillary and mandibular cheek teeth. Quantitative measurements of transverse dentine thickness around pulp cavities, dentinal tubule diameters and densities, and enamel prism diameters were made. Left lower incisors (301) were extracted from 7 donkeys and 6 horses for micro-hardness determination of enamel, primary and secondary dentine using a Knoop Hardness indenter. No significant difference between donkey and horse incisor microhardness was demonstrated. Examination of 19 donkey skulls at post mortem examination showed donkeys to have a higher degree of anisognathia (27%) compared to horses (23%). Post mortem dental examination of 349 donkeys (median age 31) demonstrated a high prevalence of dental disease (93%) and in particular cheek teeth diastemata (85%). Furthermore, age was associated with increasing prevalence of dental disease and diastemata. Diastemata were also associated with the presence of other dental disorders and with colic-related death in affected donkeys. Quantitative measurements of 45 diastemata from 16 donkeys showed no difference in the medial and lateral width of diastemata but periodontal pockets were deeper laterally. The definition of valve and open diastemata were confirmed. Pulp exposure, dental caries and periodontal disease were examined in detail (54 skulls) at post mortem. A total of 19 teeth were extracted for further detailed examination as performed in normal anatomy. Clinical dental examinations were performed on 357 donkeys in the U.K. that were selected for age distribution, and the prevalence of dental disease in different age groups was found to increase from 28% in the youngest group (age 0-10 years) to 98% in the oldest group (age > 35 years). An increased prevalence of most dental disorders with age was demonstrated as was an association between dental disease and weight loss, poor body condition score, supplemental feeding and previous episodes of colic. Clinical dental examination of 203 working donkeys in Mexico showed similar types of dental disorders as found in the U.K. study, with dental disease present in 62%, of which 18% required urgent dental treatment. There was a significant association between age groups and dental disease, and age groups and body condition score, but there was no association between dental disease and body condition score. However, body condition score was not associated with supplemental feeding or faecal egg counts either.

In my thesis I focused on the comparison of teeth in mammals and man. I compared from the viewpoint of the composition of the glass and then also from the various types of teeth transformations within demands for food and, from the viewpoint of appearance of the individual teeth, and from the perspective transformations of individual teeth. There is also focus on access issues in a single series of textbooks of natural history and biology. Where we created a simple analysis contained in the table. Next, I created a proposal of project teaching on the subject of comparison teeth of mammals and man, that serves as a guide for other teachers.

Thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Science, School of Geosciences, University of the Witwatersrand, Johannesburg, 2018 / Teeth make up the bulk of hominin fossil material and are useful in taxonomic assessments. In this thesis, discriminant function, principal components and randomised CV analyses on large samples of lower second molars (n=778) from five extant reference species, both sexually dimorphic and non-dimorphic, provide estimates of ranges of size-shape variability to be expected within a single species. However, there is evidence that diet-driven tooth-size reduction and cusp simplification has expanded the ranges of shape and size variability of Homo sapiens in some populations, in areas exposed to soft, undemanding diets since the transition to agriculture and increased use of cooking, food processing and ceramics from about 12500 years ago. Molar size and shape changes are less evident in communities retaining a hunter-gatherer subsistence strategy, requiring strong dentognathic structures with robust teeth to masticate harder, tougher foodstuffs. These factors, driving divergent variability in tooth size and shape, are unique to modern humans. Using a novel mathematically-based landmarking methodology, developed to allow the inclusion of severely worn teeth, intra-species size-shape variability was assessed from 63 lower M2s representing nine African Plio-Pleistocene species. The first hypotheses tested in this thesis address the question of which extant hominoid species might be suitable for use as analogue species for comparisons with fossil hominin molars, and whether uniquely modern-human anomalous size-shape variability exhibited by lower second molars might disqualify modern Homo sapiens for such analyses. Secondly, where lower second molar size-versus-shape variability ratios measured for fossil species do not match those of either a sexually dimorphic or a non-dimorphic extant species, evaluations are made as to whether samples attributed to single hominin species might actually represent specimens from more than one species present in the relevant assemblages, whether sexual dimorphism may have been greater in fossil species than in extant species, and whether some individual specimens attributed to any fossil species might be misclassified. Results of the analyses indicate that uniquely human subsistence strategy divergences are identifiable in the size-shape variability of lower second molars. Furthermore, specimens representing Australopithecus afarensis, Australopithecus africanus and Paranthropus robustus in this study exhibit very high variability and may indicate the presence of more than one species in their respective assemblages. / EM2018

The prevalence of pulpal involvement in young permanent teeth ranges between 0.3-36%. The outcome of Endodontic Therapy (ET) has not been widely studied in children and adolescents. Published studies that evaluated Endodontically Treated Teeth (ETT) in children and adolescents had results that varied tremendously. This variation could be due to the wide age range spanning from 6-18 years. Evaluating the predictors of survival, failure, and tooth retention between smaller subgroups within this age range may be relevant. AIM: To identify and assess variables associated with the outcome of ETT in 6-18 year old subjects stratified by age and to compare the results to the general population. METHODS: Retrospective chart review along with clinical follow up of subjects that received ET at BUGSDM between 2007-2015 at age 6-18 years. RESULTS: ET of the young permanent tooth resulted in 85% tooth survival and 91% retention. Patient age and tooth type were significantly related to survival and retention of ETT. CONCLUSIONS: Survival and retention of ETT observed among children and adolescents were similar to observations in adults. ET is more likely to survive when it is performed at an older age (15-18 years), or on an anterior tooth. This suggests that the longer ET is prevented through proper oral hygiene measures and preventive dental care, the better the likelihood of survival and retention of ETT in young patients.

Objective: Natural tooth is composed of different structures with different optical properties. The aim of this observational study is to investigate the difference between the dentin color and the tooth color in CIE LAB* color coordinates and Delta E at incisal, middle and cervical thirds of maxillary anterior teeth . Methods: Sound natural extracted maxillary anterior teeth were used. Horizontal and vertical grooves were cut into enamel to be used as a reference for the measurement locations. Teeth were mounted on a dentoform with a bite registration material (Regisil, DENTSPLY). An image of the tooth was captured with an image-based spectrophotometer (Spectroshade Micro, MHT Optic Research). The thickness of enamel for each tooth was determined with a radiograph. Enamel was grinded to expose the facial dentin with a diamond bur. Then an image of the facial dentin was captured. The color of the tooth and the dentin was compared based on the CIE LAB color space at nine locations in the incisal, middle and cervical thirds. Color difference between the whole tooth color measurement and the corresponding dentin color measurement was calculated for each tooth. Results: 89 maxillary extracted anterior teeth were included in the study. Based on the paired-samples t-test, the data provided evidence that there was a significant difference between the color of dentin and the color of tooth (p<0.05 in each instance), except for the color parameter L* measured at the incisal third (p=0.9251). For parameters L* and b*, the results indicated that the mean color of dentin was greater than the mean color of tooth, while it was lower for parameter a*. Conclusion: The results of this study suggest that the dentin is higher in value than the tooth. In addition, the dentin color was higher in b* but lower in a* than the tooth color. The difference between the color of the tooth and the dentin was the least in the cervical third.

Abstract not available

Master of Dental Surgery / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Master of Dental Surgery / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au