BackgroundTo evaluate the closure of midline diastema using the Neodymium-Iron-Boron magnets and to compare the treatment duration of midline diastemas with the use of magnets compared to regular orthodontic treatment.Material and MethodsThirty patients with age group 12 to 30 years with the midline diastema ranging from 0.5 to 3mm were selected. These patients were divided into two groups. Diastema closure in one group was accomplished by conventional method, in other group was done with Ne2Fe14B magnets. These magnets were fitted to the labial surfaces of the maxillary central incisors such a way that the opposite poles of the magnets face each other. At each appointment, study models and radiographs were taken for study subjects and the midline diastema was measured using digital vernier calipers on the study models obtained. Descriptive statistics carried out using Paired t-test.ResultsSubjects treated with Ne2Fe14B magnets showed a significant difference compared to fixed orthodontic appliance subjects with respect to time of closure, rate of space closure and incisal inclination. Significant difference between 2 groups with reduction of 64.6 days in time to diastema closure in subjects treated with Ne2Fe14B magnets (P<0.05).ConclusionsNe2Fe14B magnets more efficient in complete closure of mid line diastema in less duration of time. Key words:Midline diastema, Ne2Fe14B magnets, rare earth magnets, space closure.

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Introduction: The study aims to evaluate the effect of osteotomies with and without Pterygomaxillary disjunction (PMD) during Surgical Assisted Rapid Maxillary Expansion on the displacement pattern and stress distribution of Dental and Skeletal structures of the Nasomaxillary (NM) complex by a modified rapid maxillary expansion (RME) Hybrid appliance. Materials and Methods: A CT scan of a 20-year-old adult with maxillary constriction and the posterior bite was utilized for the restructuring of the finite element model. Five different meshed models were created individually with varying procedures of the osteotomy. A posteriorly anchored Hybrid-Hyrax appliance was utilized for RME. Groups included Group 0 - Control group without osteotomy; Group I - Only Midpalatal osteotomy; Group II - Only Subtotal Le fort I; Group III - Both Midpalatal and Subtotal Le fort I without PMD; Group IV - Midpalatal + subtotal Le fort I with bilateral PMD. The displacement pattern and stress distribution in all three dimensions were recorded and analyzed using analysis of variance and post-hoc Tukey test. Results: Group IV with PMD exhibited the highest stress dissipation and displacement of the skeletal and dental structures followed by Group III osteotomies. The highest stress concentration was at midpalatal suture (292 MPa) for Group III osteotomies. There is no statistical difference between Group III and Group IV osteotomies for many of the parameters measured (P > 0.05). Conclusions: Posteriorly anchored Hybrid appliance without PMD is as effective as that with of PMD.

Every practicing orthodontist today is aware of the importance of considering arch form in the attainment of a functional orthodontic correction [1] . Arch perimeter or circumference prediction is an essential component when Tooth Size Arch Length Discrepancy (TSALD) is estimated. Arch perimeter is the distance from mesial contact of the permanent molar on one side to the mesial contact of the permanent molar on the other side, with the line connecting the buccal/incisor tip points in the intervening teeth. This is most evident when seeking to resolve dental crowding or arch-length discrepancy (ALD) [2] . The shape of the arch form of maxillary and mandible resembles that of the various geometric forms such as including ellipse, parabola, hyperbola, and catenary curve [3] , [4] , [5] , [6] . Ellipse is the best form that fits the shape of the Maxillary arch [1 , 2] . The mathematical equation formulated by Srinivasan Ramanujan in 1914 for widely considered to be the most accurate for calculation of the circumference of an ellipse is [7] . The computation of the circumference of the ellipse by this equation requires two values- ‘ a’ and ‘ b,' the semi-major and semi-minor axis [half of the major axis and minor axis of the ellipse] respectively [8] . The perimeter (P) of an ellipse is given by the formulae; = π(a+b){1+(3h/(10-√(4-3h))}; where h=(a-b) 2 /(a+b) 2 and calculated Maxillary arch perimeter (CP) =1/2 P. This necessitates a complex series of steps, and to overcome this, a statistical formula is developed by algorithm steps for mathematical equation where perimeter can be directly obtained by just two inputs ’a’ and ’b’ in excel sheet. We correlated this calculated arch perimeter (CP) with directly measured perimeter (MP) and marginal difference estimated in three different classes of malocclusion.