An orthopantomography study of prevalence of impacted teeth
ABSTRACT Orthopantomograms of a total of 4,063 individuals were included in the study and were taken from patients of the Institute of Dentistry, University of Turku. Impacted teeth were found in 14.1% of the patients. The teeth most frequently impacted were the third molars, 76.1%, and of these, no difference between the maxilla and mandible was observed. No difference in sex in the prevalence of third molars was observed. The prevalence of impacted maxillary cuspids was higher in females than in males. When the prevalence of the third molars in different age-groups was studied, a decrease was found with an increase in age. The prevalence of impacted cuspids was approximately the same in different age-groups.
Conference Paper: Frequency invariant beamforming in very short arrays[Show abstract] [Hide abstract]
ABSTRACT: Frequency invariant beam patterns are often required in systems using an array of sensors to process broadband signals. Although several methods have been proposed to design a broadband beamformer (typically realized by an FIR filter for each sensor) with a frequency invariant beam pattern, till now the case in which the spatial aperture is shorter than the involved wavelengths has not been addressed. In such a case, the use of a superdirective beam pattern is essential to attain an efficient system. In this paper, a novel method to design a broadband beamforming that produces a frequency invariant beam pattern for a data-independent superdirective array is proposed and compared with other potential approaches. The method generates a far-field beam pattern that reproduces the desired profile over a very wide frequency band, also if the array is shorter than the wavelength. Two steps are necessary: (1) the generation of many apodizing windows at different frequency values by a stochastic method; (2) the synthesis of the FIR filters with the Parks-McClellan technique. At the end of the design chain, the very simple implementation and the robustness to array imperfections of the attained broadband beamformer increases the applicability of the system, for instance, in underwater communications for small vehicles.OCEANS '04. MTTS/IEEE TECHNO-OCEAN '04; 12/2004
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ABSTRACT: The purpose of this study is to assess the prevalence and agenesis of third molars, their impaction status, and the time and sequence of their eruption in the students of Asian-Indian population. One hundred students with ages ranging from 17.5 to 20.0 years were randomly selected. This age group was selected because this is the age at which third molars normally begin to erupt. Students who had undergone any tooth extraction or orthodontic treatment previously were not included in the study. The incidence of congenital missing third molars was 11.5%, with a higher incidence in females. Of the third molars present, 31% were in mesioangular position, 42% were in the vertical position, 27% were in the distoangular position, and none were in the horizontal position. Of the 354 teeth examined, 24% of teeth were found to be erupted and 76% were in various stages of eruption. The level of eruption of third molars was 27% at A; 39%, B; and 34%, C. The present study showed that at the baseline (mean age, 19.3 years), 24% of third molars were erupted, 76% were in various stages of eruption, and 11.5% were congenitally missing in the Asian-Indian student population.Journal of Oral and Maxillofacial Surgery 06/2005; 63(5):640-5. · 1.33 Impact Factor
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ABSTRACT: The development of wisdom teeth occurs within a definite period of time. The correlation of wisdom tooth development and chronological age has been frequently used for several purposes, e. g. the start of orthodontic treatment, estimates of age or, for legal and anthropological purposes. Wisdom teeth are frequently impacted in the bone. It has been argued that the impaction of wisdom teeth can cause a delay in root development. This thesis could have bearing on age estimations in teenagers and young adults and the timing of dental treatment. The aim of this study was to determine whether the impaction of wisdom teeth influences the velocity of root formation. The dental x-rays (orthopantomograms) of 1053 outpatients were evaluated (age: 14 to 24 years). The condition "impacted" or "not impacted" was registered for each wisdom tooth present. The impaction types were further classified. The data were then calculated using statistical tools. The correlation between the developmental stages of wisdom teeth and the chronological age is high. However, neither any impaction type nor the whole group of retained wisdom teeth showed a statistically significant different course of root development compared to the root development of non-retained wisdom teeth. This study provides evidence for the lack of bearing of wisdom teeth topography on the growth stages of the dental roots within definite time intervals, based on the evaluation of orthopantomograms only. Obviously, the variations of root formation in the selected chronological periods are greater than the variations attributable to possible periods of delay in root formation of retained wisdom teeth. These results could have some importance for the fields of dental anthropology and dentistry.Annals of Anatomy - Anatomischer Anzeiger 11/2003; 185(5):481-92. · 1.96 Impact Factor