Background:Palatal rugae comprises three to seven ridges radiating out tangentially from the incisive papilla on the anterior part of the palate. These rugae patterns are studied for various reasons, mainly in the fields of anthropology, genetics, orthodontics, prosthodontics, and forensic science.Objective:To compare the palatal rugae pattern in two different populations (Manipuri and Kerala), and to assess the predominant pattern if any in the selected groups.Materials and Methods:Sixty maxillary study models (30 from each group including males and females) were examined in the age group ranging from 17 to 23 years. Palatal rugae pattern were analyzed on the right and left sides of the palate for total number, length, shape, direction, and unification.Results:After analyzing the rugae patterns in both the groups and between the two sides of the palate, the wavy pattern was found to be predominant followed by curved, straight, and circular in overall population. Manipuri population showed predominant curved shape than the Kerala population and was statistically significant. Females in general had slightly more rugae than males and the left side of the palate showed comparatively more number of rugae than on the right side.Conclusion:A statistically significant association between the shape of the rugae and population exists although, subtle. Parameters like direction and unification need more attention for better understanding.

Aim The objective of this study was to evaluate density changes around the apices of teeth during orthodontic treatment by using digital subtraction radiography to measure the densities around six teeth (maxilla central incisors, lateral incisors, and canines) before and after orthodontic treatment in 36 patients and also assess treatment variables and their coorelation with root resorption. Materials and methods A total of 36 consecutive patient files were selected initially. The selected patients presented with a class I or II relationship and were treated with or without premolar extractions and fixed appliances. Some class II patients were treated additionally with extraoral forces or functional appliances. External apical root resorption (EARR) per tooth in millimeters was calculated and was also expressed as a percentage of the original root length. Image reconstruction and subtraction were performed using the software Regeemy Image Registration and Mosaicing (version 0.2.43-RCB, DPI-INPE, São José dos Campos, São Paulo, Brazil) by a single operator. A region of interest (ROI) was defined in the apical third of the root and density calibration was made in Image J® using enamel (gray value = 255) as reference in the same image. The mean gray values in the ROIs were reflective of the change in the density values between the two images. Statistical analysis The root resorption of the tooth and the factors of malocclusion were analyzed with a one-way ANOVA. An independent t-test was performed to compare the mean amount of resorption between male and female, between extraction and nonextraction cases. The density changes after orthodontic treatment were analyzed using the Wilcoxon signedrank test. In addition, the density changes in different teeth were analyzed using the Kruskal-Wallis test. The cut-off for statistical significance was a p-value of 0.05. All the statistical analyses were carried out using SPSS (version 13.0 for Windows, Chicago, IL, USA). Results Gender, the age at which treatment was started and Angle's classification was not statistically related with observed root resorption. The mean percentage density reduction as assessed by DSR was greatest in both central incisor: by 27.2 and 25.2% in the upper-right and upper-left central incisors, respectively, followed by the upper-right and upper-left canine teeth (23.5 and 21.0%) and then the upper-right and upper-left lateral incisors (19.1 and 17.4%). Conclusion Tooth extraction prior to treatment initiation and the duration of orthodontic treatment was positively correlated with the amount of root resorption. DSR is useful for evaluating density changes around teeth during orthodontic treatment. The density around the apices of teeth reduced significantly after the application of orthodontic forces during treatment. Clinical significance Assessment of density changes on treatment radiographs of patients undergoing orthodontic therapy may help in the monitoring of external apical root resorption during course of treatment. How to cite this article Sunku R, Roopesh R, Kancherla P, Perumalla KK, Yudhistar PV, Reddy VS. Quantitative Digital Subtraction Radiography in the Assessment of External Apical Root Resorption Induced by Orthodontic Therapy: A Retrospective Study. J Contemp Dent Pract 2011;12(6):422-428.

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Abstract.A mobile Adhoc network (MANET) is a collection of mobile nodes to form a temporary network without use of any predefined infrastructure. Direct communication is possible only when two nodes lie within their sensing range; otherwise communication is made through intermediate nodes till the destination is reached. Such type of networks can allow any node to join in the network or leave the network at any instant of time. So any node can act as a host or the router in the network, which results in security issues in MANETs. A well known attack in MANETs is a Black hole attack. In this paper, we present a simple but effective method called Code Division Security Method (CDSM) for security in order to prevent Black hole attack in MANETs. Black hole node is a malicious node which can mislead a normal node to forward the data through it and corrupt the data so that it can degrade the performance of the network. We validate our approach using network simulator with an example.

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