Aim: To evaluate the possible cytotoxic damage to the oral mucosal cells in healthy patients undergoing orthodontic treatment with clear aligners. Materials & Methods: 20 patients who required orthodontic treatment were chosen. The rst set of aligners were fabricated for each patient using a PETG material. Patients were instructed to wear the aligners for 22 hours a day for 15 days. Buccal mucosal cells were sampled at two time intervals T0- pre treatment and T1- after 15 days and were immediately smeared onto a clean glass slide. The smears were immediately xed in isopropyl alcohol, following which the slides were hydrated with distilled water, stained with the Papanicolaou method and subjected to cytomorphometric analysis. The two samples obtained at T0 and T1 for each patient were compared to check for an increase in number of micronucleated cells. Student Paired t Test was used to compare the mean micronuclei count between pre and post treatment. Results: The mean Micro Nuclei count in the post treatment period was signicantly higher (4.50 ± 1.96) as compared to pretreatment period (3.10 ± 1.73) with a mean difference of -1.40 at P=0.007. Conclusion: Within the experimental limits of this study the PETG material used for fabrication of aligners resulted in a change in the nature of buccal mucosal cells with an increase in the number of micronuclei which is an indicator for cytotoxicity. The PETG material may have a cytotoxic effect on the cells of the oral mucosa.

In orthodontic treatment, anchorage control is essential for success. A recent development, stationary anchorage (microimplants) eliminates one of the uncertainties of orthodontic tooth movement by offering absolute control over potentially undesirable counter movements. The objective of this study was to establish a 3D finite element model for microimplant and to analyze the influence of different angulations to the long axis of the teeth (30-90°) on the biomechanical characteristics of orthodontic anchorage implant-bone interface. Results of this study showed that largest stress and deformation was seen in the cortical bone and upper region of trabecular bone. Stress and deformation increased as the angulations of the implant to the long axis of the tooth increased. As the angulation of the implant to the long axis of maxillary 1st molar increased, stress and deformation also decreased. Maximum stress and displacement were recorded when implant was placed perpendicular to the long axis of maxillary 1st molar. How to cite this article Naidu DL, Harini T, Prasad CMSK, Lakshmi HV, Lokesh NK, Dharmesh HS. Biomechanical Characteristics of Microimplant for Anchorage in Orthodontics: A 3D Finite Element Model Study. J Contemp Dent Pract 2013;14(6):1076-1079.

Study models accurately represent the teeth, their supporting tissues and the relationship between upper and lower teeth in centric occlusion. They contribute greatly to diagnosis and treatment planning, to compare pre-and post-treatment changes and are valuable instructional and illustrative aids during consultation with patients. [1] Accurate trimming of orthodontic study models facilitates proper diagnosis and treatment planning. Well-trimmed, esthetically pleasing models, reflect the practitioner's attention to detail and are a part of the patient's legal treatment record. [2,3] American board of orthodontics prescribes certain specifications for plaster study models for universal acceptance. [4]

Anchorage is the most important consideration in any orthodontic treatment planning. The main aim of the D-Arch is to produce absolute anchorage in all three dimensions which cannot be obtained in the conventional transpalatal arch. D-Arch is a rigid, noninvasive appliance to avoid unwanted tooth movement.

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