The knowledge related to the methodology of the field TRIAL study as a type of intervention studies, yet for many of our researchers is not fully understood. The aim of the current study was a better understanding of conducting this type of research. Field TRIAL studies are done on healthy individuals and aim to prevent. These types of studies such as clinical TRIALs are performed on both individual and collective levels. One type of these studies is Community Intervention TRIAL which is usually done on a large scale population. Field TRIAL study should be carried out in stages, such as the formulation of hypotheses, selection of the population (reference population, study population, and sampling), measuring the baseline variables (before conducting preventive intervention), random allocation of subjects to intervention and control groups, doing interventions and measuring outcome. The methodology of field TRIAL studies is very similar to clinical TRIALs. The difference is that field TRIALs are conducted on healthy individuals and aim to prevent and also the sample size required to this type of study is relatively more, and these studies are usually time consuming and costly.

The purpose of this study was to apply recurrence plots on event related potentials (ERPs) recorded during memory recognition tests. EEG signals recorded during memory retrieval in four scalp region were used. Two most important ERP’s components corresponding to memory retrieval, FN400 and LPC, were detected in recurrence plots computed for SINGLE-TRIAL EEGs. In addition, the RQA was used to quantify changes in signal dynamic structure during memory retrieval, and measures of complexity as RQA variables were computed. Given the stimulus, amplitude of the RQA variables increases around 400ms, corresponding to dimension reduction of system. Furthermore, after 800ms these amplitudes decreased which can be as a consequence of an increase in system dimension and complexity and back to its basic state. The mean amplitude of Old items was more than New one. Furthermore we applied statistical analysis (t-test) to find meaningful difference between features extracted from nonlinear measures. Using this method, we found its ability to detect memory components of EEG signals and to do a distinction between Old/ New items. In contrast with linear techniques, recurrence plots and RQA do not need large number of recorded TRIALs, and they can indicate changes in even SINGLE-TRIAL EEGs. RQA can also show differences between old and new events in a memory process.

Background and Aim: Although orthodontists have long recognized that the EXTRACTION (Ext) of premolars often is accompanied by changes in the soft tissue profile, investigations indicate that the soft tissue does not always respond favorably to hard-tissue retraction. This study was designed to evaluate the effects of treatment, with and without premolar Ext, on the lateral facial profiles of borderline patients with particular reference to the curvature of the upper and lower lips.Materials & Methods: Eighty-nine border line patients were included in this study. 41 patients were treated with a non-EXTRACTION (Non-Ext) protocol, 16 patients were treated with EXTRACTIONs of 5.5, 18 patients with 4.4 and 14 patients with 4.5. All pre-and posttreatment lateral cephalograms were traced and analysis by one examiner. To quantify the soft tissue effects of growth and treatment, the depths of the upper and lower lip curves were calculated in two ways relative to the PM reference line and anterior soft tissue reference line.Results: The changes in depth of upper and lower lip curves were statistically significant (P<0.001).The Non-Ext group showed an increase in depth of upper and lower lip curves, whereas the Ext group showed a decrease in depth of upper and lower lip curves. No significant differences were found between the various EXTRACTION sequences (5.5, 4.4, 4.5) for depth of the upper and lower lip curves changes.Conclusions: l) The upper and lower lip changes were significant; more retrusive in the Ext group and more protrusive in the Non-Ext group. 2) There were no significant post treatment differences in the depths of upper and lower lip curves between premolar EXTRACTION sequences.

Background & Aim: EXTRACTION of first premolars and their influence on the third molars' eruption and impaction has been of concern to dental profession. The aim of this study, was to determine the relation between the changes of third molar angulation and the first premolar EXTRACTION in orthodontic treatment.Materials and Methods: This analytical study was carried out on total 90 subjects selected from two orthodontic clinics. Forty five subjects (14 males and 31 females) 14.46±1.64 years old treated with EXTRACTION of four first premolars (EXTRACTION group) and the other 45 subjects (13 males, 32 females) 13.9±1.99 years old treated by nonEXTRACTION were studied. Lateral cephalometric and panoramic films were studied before and after treatment. Eight angles in panoramic, four angles and 4 linear variables on the lateral cephalometric films were measured. Age, gender, amount of crowding in both dental arches and treatment duration were matched in the two groups. Student t and chi square tests were used to analyze the data.Results: The upper eruption space and the lower eruption spaces were more in EXTRACTION group and the difference was significant (P=0.02, P=0.004, P<0.001). The changes of third molar angulation were not significant between the two groups. Eruption rate of the third molars in both arches were more in EXTRACTION group and the difference was significant (P<0.001).Conclusion: EXTRACTION of the first premolars did not influence the changes in the third molar angulation, while it affected the third molar eruption by space creation. It seems that EXTRACTION of the first premolars is not a way for secure eruption of the third molar.