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Abstract: Murray James Barrett (1916–1975) graduated from the University of Adelaide''s Bachelor of Dental Surgery programme in 1939 and subsequently became a colleague of Professor Thomas Draper Campbell (1893–1967). Campbell''s passion for dental anthropology and his special interest in food habits and dental disease inspired Barrett to commence a longitudinal growth study in the 1960s of Aboriginal Australians living at Yuendumu in the Northern Territory of Australia. This study, referred to as the Dentgro project, involved the collection of dental records, growth data and cultural information about the Wailbri people. Murray Barrett''s application of computer technology enabled him to automate the entry of data derived from the Dentgro study and to develop programmes to analyse those data. The collection of dental casts (over 1700 serial casts for more than 450 individuals) and other records have provided a unique resource for research and teaching purposes. The casts have been in constant use for over 40 years providing insights into many aspects of dental development, including: the timing and sequence of tooth emergence; the nature and extent of variation in dental crown size and morphology in human populations; the patterns of growth in the dental arches over time; the range of occlusal variation between individuals; and the effects of wear on the dentition. The Yuendumu cast collection, representing a population with limited exposure to European customs and dietary habits, continues to attract the Adelaide School of Dentistry many interstate and overseas researchers interested in genetic and environmental influences on human dental development. [Copyright &y& Elsevier]

Abstract: Sexual differences in the crown units of mandibular molars were investigated in Australian Aborigines. The first and second deciduous molars (dm1 and dm2), and first to third permanent molars (M1, M2 and M3) were measured on dental casts using a sliding caliper. Measurements of tooth crowns included overall mesiodistal and buccolingual diameters, as well as the mesiodistal and buccolingual diameters of the trigonid and talonid. Percentage dimorphism values were greater in the talonid dimensions than the trigonid, indicating that sex differences tend to be larger in the later-developing crown units. Sex differences in mesiodistal diameters increased from dm1 to M2 but decreased for M3, the tooth that showed the least dimorphism of all the molars. This result seems to be due to the marked variability in size of the M3 between individuals. [Copyright &y& Elsevier]

Corrected head position (CHP) has been simulated by using the Frankfurt horizontal (FH) for over 100 years but FH varies between individuals. Because CHP is biologically relevant for orthodontic diagnosis and treatment planning, orthognathic surgical planning, and art, this study examined relationships between head position and selected cephalometric planes. Natural head position cephalograms of Aboriginal Australians and two contemporary samples from private orthodontic practices were analysed. Each sample comprised 40 individuals (20 males and 20 females). The Aboriginal Australian sample comprised longitudinal data (T1 early adolescent, T2 late adolescent, and T3 adult), enabling examination of natural head position (NHP) reproducibility over a period of approximately 8 years. Results of reproducibility differences revealed an absolute mean=2.9°, range=−7.9° to 8.2°, and standard deviation=3.6°. Stable basicranial line (SBL), neutral horizontal axis (NHA), FH, palatal plane (P plane), and Krogman–Walker plane (KW plane) demonstrated near parallelism and their mean angulations from the true horizontal (HOR) ranged between −4.6° and 2.4°. While NHP is not consistently reproducible at the individual level, the combined use of multiple planes such as SBL, P plane, and KW plane enables a more consistent CHP to be achieved. [ABSTRACT FROM AUTHOR]

The nature and frequency of dental wear facets were studied in a sample of 18-year-old Aborigines, 28 males and 31 females, living at Yuendumu in the Northern Territory of Australia. Facet frequencies were scored indirectly using dental models for all permanent teeth, except third molars, and evidence of non-masticatory tooth grinding in eccentric jaw positions was also recorded. The interplay between attrition and abrasion in an individual over time was assessed by examining facet appearance on serial dental models obtained at approximately yearly intervals from 7 to 25 years of age. Facetting was found to be a very common feature of the Aboriginal dentitions, with frequencies ranging from around 65% for pre-molars to about 90% for molars. Evidence of extreme mandibular movement was noted in 93% of males and 100% of females. The longitudinal observations indicated that wear facet definition varied over time, apparently due to episodes of tooth grinding superimposed on continually-acting abrasive influences. These results show that facetting on teeth associated with extreme mandibular positions and, by inference, the related behaviour of tooth grinding or bruxism are very common features in dentitions of Australian Aboriginals living an essentially non-industrial way of life. [ABSTRACT FROM AUTHOR]

Abstract: Objective: In addition to its role as a remineralizing agent in preventing dental caries, calcium product (CPP–ACP) delivered as a mousse (Tooth Mousse®, TM) can reduce erosion of enamel and dentine. The aim of this study was to determine whether CPP–ACP could also reduce erosive tooth wear involving toothbrush abrasion. Methods: Flat, polished enamel and dentine specimens (n =72) were subjected to 10 wear regimes, with each regime involving erosion in 0.3% citric acid (pH 3.2) for 10min followed by toothbrush abrasion in a slurry of fluoride-free toothpaste and artificial saliva (1:3 ratio by weight) under a load of 2N for 200 cycles. The specimens were immersed in artificial saliva for 2h between wear regimes. In the experimental group 1, TM (containing CPP–ACP) was applied at the beginning of each wear episode for 5min whereas TM− (without CPP–ACP) was applied in the experimental group 2. No mousse was applied in the control group. Results: TM significantly reduced enamel wear (mean±S.E., 1.26±0.33μm in the experimental group 1 vs 3.48±0.43μm in the control group) and dentine wear (2.16±0.89μm in the experimental group 1 vs 10.29±1.64μm in the control group), and dentine wear was significantly less in the experimental group 1 than in the experimental group 2 (5.75±0.98μm). Conclusion: The finding that TM reduced erosive tooth wear involving toothbrush abrasion, probably by remineralizing and lubricating eroded tooth surfaces, may have implications in the management of tooth wear. [Copyright &y& Elsevier]

Abstract: There have been very few studies of frontal sinus development and its association with other growth parameters in humans. The aim of this study was to investigate the relationship of frontal sinus development with somatic and skeletal maturation in a sample of Aboriginal Australians. The sample comprised 31 individuals, of whom 17 were males and 14 females. For the selected subjects the following records were available: lateral head radiographs, hand–wrist radiographs and stature recordings, generally covering the age range from 7 to 18 years. Descriptive statistics for frontal sinus size, skeletal ossification and body height were calculated at yearly intervals and comparisons made between the sexes. Growth velocities in frontal sinus height, frontal sinus depth and stature were also calculated for both sexes. The frontal sinus was found to display a well-defined adolescent growth spurt, with its peak velocity occurring after the peak velocity in body height. Females were found to attain peak velocity in sinus height earlier, on average, than males but they attained peak velocity in sinus depth at a similar age to males. The sequence of hand–wrist ossification events followed a similar pattern in both sexes, with events in females occurring approximately one year earlier than those in males. These results indicate that an adolescent spurt is present in frontal sinus growth and that the spurt tends to occur after statural velocity has peaked. Hand–wrist ossification events also tend to have a close relationship to peak statural and frontal sinus velocity and these relationships may be useful in clinical situations for predictive purposes. [Copyright &y& Elsevier]

Abstract: Aims: Anomalies of tooth number may not be isolated conditions but may have wider associations in the development of the dentition including tooth size. This study aimed to examine links between hypodontia, supernumerary teeth and crown size, considering the effect on the development of the whole dentition and so increase understanding of the aetiology of these conditions. Methods and results: The patients, who were all of European ancestry, were 60 young adults (30 males and 30 females) with hypodontia and 60 age and sex matched controls together with 60 young adults (39 males and 21 females) with supernumerary teeth and 60 age and sex matched controls. Hand measurements of mesiodistal and buccolingual dimensions were made of the teeth on dental study models using Mitutoyo electric callipers. The mean value of two measurements was used and intra-operator and inter-operator reliability determined. Patients with hypodontia had smaller teeth than the control group and this difference was statistically significant (p <0.05) for all teeth except the MD dimensions of 13, 23, 24 and 44. The difference in size was greatest for the BL dimensions in hypodontia patients. Further, the greater the number of missing teeth the smaller the tooth size. The hypodontia patients also showed higher variability in tooth dimensions than the control group. Patients with supernumerary teeth had larger teeth than the controls, with the greatest differences in the MD dimensions. In both hypodontia and supernumerary patients the differences in tooth size were generalised throughout the dentition. Conclusions: In anomalies of tooth number the size of teeth is also involved. In patients with hypodontia and supernumerary teeth the crown size of the whole dentition is affected. These findings are compatible with a multifactorial aetiology of these conditions. [Copyright &y& Elsevier]