In vitro study of four types of elastics

It is significant to look at the performance of each material against itself over time in each of the two stated distances. The material Cinch seems to perform best over the short rather than the long span. Power thread appeared to perform, somewhat, better over the long rather than the short distance. Power chain showed similar performance in both the long and the short spans. Elastic ligature thread exhibited very consistent force delivery specially over the long span. With regards to the predictability of force delivery over time, it seems that Elastic ligature thread experienced the least decay in force delivery. Power thread, Cinch and to a lesser extent Power chain seem to deliver lesser decay of force when their initial activation is less. The difference in initial level of activation may account for the difference in behaviour of these materials over the short and long spans. There is perhaps, an optimal range of initial activation producing lesser decay of force delivery. Our results are in agreement with those of Andreasen and Bishara [1970], who also found that the initial drop of force is greater for synthetic material while the natural elastic [J 51] is more constant in its delivery of force, that is to say, the reliability of applied forces is greater in the natural elastic J 51 because the variability is less than that of the three synthetic elastics. It can be concluded that the initial force for the synthetic elastics should be approximately twice that of the force wanted to be applied on the teeth after the first hour both for short and long spanned distances. In accordance with Howard and Nikolai it was found that Elastic threads, as active components of the orthodontic appliance, is in the finer control of initial force levels than is possible with elastic bands or chains provided proper knot tying is, of course, achieved

Alexandria analysis: radiographic cephalometric standards for Egyptian adults

A radiographic cephalometric study was performed on a group of Egyptian University students. The subjects included 100 males and 100 females, between 18 and 25 years of age and with clinically acceptable occlusion and harmonious facial features. None of them had undergone orthodontic treatment. The object of this study is to establish craniofacial and soft tissue standards to be used by the clinicians on the Egyptian population. Twenty two angular measurements, thirteen linear measurements, and three ratios were established covering the most significant skeletal, dental and soft tissue parameters. The data obtained is presented in a convenient clinical table to assist orthodontists in diagnosis and treatment planning

Soft tissue analysis of the face in egyptian young adults

A cephalometric study of soft tissue analysis was performed for a random sample of 500 Egyptian young adults with an age average of 21.5 years. The means and standard deviations were calculated for seven linear measuremets and Student t test were obtained for statistical comparisons. The sex effect was significant for all the measurements, as there was a larger thickness of soft tissue in males than females. Hopefully the information derived from this study will aid the clinicians in their consideration of the soft tissue mask during the course of diagnosis and treatment planning