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Background and Objectives: This study was conducted to determine the effective method to torque the incisor with thermoplastic aligner using a three-dimensional (3D) finite element method. Materials and Methods: Three finite element models of maxilla and maxillary dentition were developed. In the first model, thermoplastic aligner without any auxiliaries was used. In the second and third models, thermoplastic aligner with horizontal ellipsoid composite attachment and power ridge were used, respectively. The software used for the study was ANSYS 14.5 FE. A force of 100 g was applied to torque the upper right central incisor. The resultant force transfer, stress distribution, and tooth displacement were evaluated. Results: The overall tooth displacement and stress distribution appeared high in the model with power ridge, whereas the root movement was more in the horizontal ellipsoid composite attachment model. The model without any auxillaries produced least root movement and stress distribution. Conclusion: Horizontal ellipsoid composite attachment achieved better torque of central incisor than the model with power ridge and model without any auxillaries.

Sir, Our patient who had concurrent chronic lymphocytic leukemia and hairy cell leukemia, viral serological markers including HIV and hepatitis viruses B and C were tested by the highly sensitive chemiluminescent immunoassay method. With this screening immunoassay, although false positivity can occur, the probability of false negativity is extremely low. This patient tested negative for all the three viruses. He was a previously fit and well gentleman and in light of the above negative tests, we did not think it prudent to further pursue CD4 counts and viral load estimation by polymerase chain reaction. These details could not be incorporated in the original case report due to word limit restrictions. However, the point raised of HIV predisposing to multiple lympho-proliferative malignancies is well taken. Financial support and sponsorshipNil.

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