Precise Insertion of Orthodontic Miniscrews with a Stereolithographic Surgical Guide Based on Cone Beam Computed Tomography Data: A Pilot Study

Purpose: Orthodontic miniscrews are commonly used to achieve absolute anchorage during tooth movement. One of the most frequent complications is screw loss as a result of root contact. Increased precision during the process of miniscrew insertion would help prevent screw loss and potential root damage, improving treatment outcomes. Stereo lithographic surgical guides have been commonly used for prosthetic implants to increase the precision of insertion. The objective of this paper was to describe the use of a stereolithographic surgical guide suitable for one-component orthodontic miniscrews based on cone beam computed tomography (CBCT) data and to evaluate implant placement accuracy. Materials and Methods: Acrylic splints were adapted to the dental arches of four patients, and six radiopaque reference points were filled with gutta-percha. The patients were submitted to CBCT while they wore the occlusal splint. Another series of images was captured with the splint alone. After superimposition and segmentation, miniscrew insertion was simulated using planning software that allowed the user to check the implant position in all planes and in three dimensions. In a rapid-prototyping machine, a stereolithographic guide was fabricated with metallic sleeves located at the insertion points to allow for three-dimensional control of the pilot bur. The surgical guide was worn during surgery. After implant insertion, each patient was submitted to CBCT a second time to verify the implant position and the accuracy of the placement of the miniscrews. Results: The average differences between the planned and inserted positions for the ten miniscrews were 0.86 mm at the coronal end, 0.71 mm at the center, and 0.87 mm at the apical tip. The average angular discrepancy was 1.76 degrees. Conclusions: The use of stereolithographic surgical guides based on CBCT data allows for accurate orthodontic mini screw insertion without damaging neighboring anatomic structures. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:860-865

Understanding Contradictory Data in Contraction Stress Tests

The literature shows contradictory results regarding the role of composite shrinkage and elastic modulus as determinants of polymerization stress. The present study aimed at a better understanding of the test mechanics that could explain such divergences among studies. The hypothesis was that the effects of composite shrinkage and elastic modulus on stress depend upon the compliance of the testing system. A commonly used test apparatus was simulated by finite element analysis, with different compliance levels defined by the bonding substrate (steel, glass, composite, or acrylic). Composites with moduli between 1 and 12 GPa and shrinkage values between 0.5% and 6% were modeled. Shrinkage was simulated by thermal analogy. The hypothesis was confirmed. When shrinkage and modulus increased simultaneously, stress increased regardless of the substrate. However, if shrinkage and modulus were inversely related, their magnitudes and interaction with rod material determined the stress response.

An analysis of accommodation needs of adults with an intellectual disability in Toowoomba and surrounding areas

Introduction The objective of this study was to analyse the accommodation needs of people with intellectual disability over the age of 18 years in Toowoomba and contiguous shires. In 2004, a group of carers established Toowoomba Intellectual Disability Support Association (TIDSA) to address the issue of the lack of supported accommodation for people with intellectual disability over the age of 18 and the concerns of ageing carers. The Centre for Rural and Remote Area Health (CRRAH) was engaged by TIDSA to ascertain this need and undertook a research project funded by the Queensland Gambling Community Benefit Fund. While data specifically relating to people with intellectual disability and their carers are difficult to obtain, the Australian Bureau of Statistics report that carers of people with a disability are more likely to be female and at least 65 years of age. Projections by the National Centre for Social and Economic Modelling (NATSEM) show that disability rates are increasing and carer rates are decreasing. Thus the problem of appropriate support to the increasing number of ageing carers and those who they care for will be a major challenge to policy makers and is an issue of immediate concern. In general, what was once the norm of accommodating people with intellectual disability in large institutions is now changing to accommodating into community-based residences (Annison, 2000; Young, Ashman, Sigafoos, & Grevell, 2001). However, in Toowoomba and contiguous shires, TIDSA have noted that the availability of suitable accommodation for people with intellectual disability over the age of 18 years is declining with no new options available in an environment of increasing demand. Most effort seemed to be directed towards crisis provision. Method This study employed two phases of data gathering, the first being the distribution of a questionnaire through local service providers and upon individual request to the carers of people with intellectual disability over the age of 18. The questionnaire comprised of Likert-type items intended to measure various aspects of current and future accommodation issues. Most questions were followed with space for free-response comments to provide the opportunity for carers to further clarify and expand on their responses. The second phase comprised semi-structured interviews conducted with ten carers and ten people with intellectual disability who had participated in the Phase One questionnaire. Interviews were transcribed verbatim and subjected to content analysis where major themes were explored. Results Age and gender Carer participants in this study totalled 150. The mean age of these carers was 61.5 years and ranged from 40 – 91 years. Females comprised 78% of the sample (mean age = 61.49; range from 40-91) and 22% were male (mean age = 61.7 range from 43-81). The mean age of people with intellectual disability in our study was 37.2 years ranging from 18 – 79 years with 40% female (mean age = 39.5; range from 19-79) and 60% male (mean age = 35.6; range from 18-59). The average age of carers caring for a person over the age of 18 who is living at home is 61 years. The average age of the carer who cares for a person who is living away from home is 62 years. The overall age range of both these groups of carers is between 40 and 81 years. The oldest group of carers (mean age = 70 years) were those where the person with intellectual disability lives away from home in a large residential facility. Almost one quarter of people with an intellectual disability who currently live at home is cared for by one primary carer and this is almost exclusively a parent.

Estimating Income Inequality in China Using Grouped Data and the Generalized Beta Distribution

There are two main types of data sources of income distributions in China: household survey data and grouped data. Household survey data are typically available for isolated years and individual provinces. In comparison, aggregate or grouped data are typically available more frequently and usually have national coverage. In principle, grouped data allow investigation of the change of inequality over longer, continuous periods of time, and the identification of patterns of inequality across broader regions. Nevertheless, a major limitation of grouped data is that only mean (average) income and income shares of quintile or decile groups of the population are reported. Directly using grouped data reported in this format is equivalent to assuming that all individuals in a quintile or decile group have the same income. This potentially distorts the estimate of inequality within each region. The aim of this paper is to apply an improved econometric method designed to use grouped data to study income inequality in China. A generalized beta distribution is employed to model income inequality in China at various levels and periods of time. The generalized beta distribution is more general and flexible than the lognormal distribution that has been used in past research, and also relaxes the assumption of a uniform distribution of income within quintile and decile groups of populations. The paper studies the nature and extent of inequality in rural and urban China over the period 1978 to 2002. Income inequality in the whole of China is then modeled using a mixture of province-specific distributions. The estimated results are used to study the trends in national inequality, and to discuss the empirical findings in the light of economic reforms, regional policies, and globalization of the Chinese economy.

Dental caries in adolescents from public schools in Maputo, Mozambique

Aim: To assess dental caries prevalence in adolescents at urban and sub-urban areas of Maputo-City, Mozambique and to identify its relationship with dental fluorosis, dental plaque, nutritional status, frequency of sugar consumption and the concentration of fluoride in public water supply. Methods: Subjects (n=601) were randomly selected from five urban schools and five sub-urban schools. Clinical examinations were performed under standardised conditions by a trained examiner using DMFT index, SiC index, fluorosis index, PHP, BMI, a sugar consumption questionnaire and water supply analysis. The bivariate analysis and Pearson correlation was used (p<0.05). Results: The mean (DMFT) was 0.9 (+/- 1.65 SD). Children in urban schools showed less dental caries (0.8 +/- 1.49SD) than children in sub-urban schools (1.1 +/- 1.80SD, p=0.03). Only 8.15% had very mild to moderate fluorosis but most presented poor oral hygiene. Cases of malnutrition were found in more sub-urban schools (n = 109; 36.22%) than in urban schools (n = 66; 22.00%) (p=0.03). The frequency of sugar consumption was higher among urban children compared to suburban schools (p<0.00). The level of fluoride in water consumption in urban schools was 0.4 ppmF, above the level of fluoride in sub-urban schools, 0.2 ppmF. Conclusion: Dental caries should not be considered a major oral health problem in Maputo at the moment. However the data suggest the implementation of a population strategy to reduce dental caries rates, in children of both urban and sub-urban areas, in Maputo.

Risk factors for dental erosion in a group of 12- and 16-year-old Brazilian schoolchildren

Background. Dental erosion is a multifactorial disease and is associated with dietary habits in infancy and adolescence. Aim. To investigate possible associations among dental erosion and diet, medical history and lifestyle habits in Brazilian schoolchildren. Design. The sample consisted of a random single centre cluster of 414 adolescents (12- and 16-years old) of both genders from private and public schools in Bauru (Brazil). The O`Brien [Children`s Dental Health in the United Kingdom, 1993 (1994) HMSO, London] index was used for dental erosion assessment. Data on medical history, rate and frequency of food and drinks consumption, and lifestyle habits were collected by a self-reported questionnaire. Odds ratios with 95% confidence intervals were used to assess the univariate relationships between variables. Analysis of questionnaire items was performed by multiple logistic regression analysis. The statistical significance level was set at 5%. Results. The erosion present group comprised 83 subjects and the erosion absent group 331. There were no statistically significant correlations among dental erosion and the consumption of food and drinks, medical history, or lifestyle habits. Conclusion. The results indicate that there was no correlation between dental erosion and the risk factors analysed among adolescents in Bauru/Brazil and further investigations are necessary to clarify the multifactorial etiology of this condition.

Dental Erosion in a Group of 12- and 16-year-old Brazilian Schoolchildren

Purpose: This study`s purpose was to assess the prevalence of dental erosion in adolescents and to investigate the association between erosion and sociodemographic characteristics. Methods: This study consisted of a single center cluster random sample of 414 adolescents (12 and 16 years old) of both genders from private and public schools in Bauru, Sao Paulo, Brazil. Two previously calibrated examiners (kappa=0.85) used the O`Brien (7994) index for assessment of dental erosion on the buccal and palatal surfaces of the permanent maxillary incisors and on the occlusal surfaces of the permanent first molars. Data on gender, type of school, and mean family income were collected by a questionnaire completed by the adolescents. Descriptive statistics were applied to the data, and the associations between erosion and sociodemographic variables were investigated by chi-square test (P<0.05). Results: The prevalence of dental erosion was 20% (N=83), with only enamel being involved (score 1). The labial surface was the most affected (16%). There were no significant differences between the presence of erosion and gender, type of school, and mean family income. Conclusions: The results indicate that dental erosion restricted to enamel was observed among adolescents in Bauru/Brazil, and there was no correlation between this condition and sociodemographic factors. (Pediatr Dent 201733:23-8) Received August 7, 2009 1 Last Revision October 13, 2009 I Accepted October 14, 2009

Association between breastfeeding duration and non-nutritive sucking habits

Objective To evaluate the relationship between breastfeeding duration and the prevalence of non-nutritive Sucking habits in children with deciduous dentition. Method A cross-sectional survey was conducted on the mothers of 551 children aged 3 to 6 years, randomly selected from public pre-schools in Sao Paulo, Brazil. Mothers were asked to complete a questionnaire that included items regarding their children`s age, gender, race, method and duration of infant feeding, as well as pacifier use and/or digit-sucking habits. According to the answers pertinent to the method and duration of infant feeding, children were assigned to five groups: 1 - never breastfed, 2 - breastfed for a period shorter than 3 months of life, 3 - breastfed for 3 to 6 months, 4 - breastfed for 6 to 9 months, and 5 - breastfed for 9 months or longer. Data were submitted to the Fisher`s exact test with Bonferroni correction for multiple comparisons to analyse possible associations between breastfeeding duration period categories and non-nutritive sucking behaviours. Results Pacifier use frequency was high in groups 1, 2, 3 and 4 (85%, 87.6%, 78% and 70%, respectively), in comparison with that in group 5 (38.6%). The prevalence of non-nutritive sucking habits was significantly reduced in children who were breastfed for nine months or longer (p=0.000). There were no statistically significant differences in the frequencies of pacifier use and/or digit-sucking habits between genders, regardless of the breastfeeding duration period. Conclusion Children aged 3-6 years who were breastfed for nine months or longer had a lower prevalence of non-nutritive sucking habits.