SBS vs Inhouse Recycling Methods-An Invitro Evaluation.

INTRODUCTION: In today's world of economic crisis it is not feasible for an orthodontist to replace each and every debonded bracket with a new bracket- quest for an alternative thrives Orthodontist. The concept of recycling bracket for its reuse has evolved over a period of time. Orthodontist can send the brackets to various commercial recycling companies for recycling, but it's impractical as these are complex procedures and require time and usage of a new bracket would seem more feasible. Thereby, in-house methods have been developed. The aim of the study was to determine the SBS (Shear Bond Strength) and to compare, evaluate the efficiency of in house recycling methods with that of the SBS of new brackets. MATERIALS AND METHODS: Five in-house-recycling procedures-Adhesive Grinding Method, Sandblasting Method, Thermal Flaming Method, Buchman method and Acid Bath Method were used in the present study. Initial part of the study included the use of UV/Vis spectrophotometer where in the absorption level of base of new stainless steel bracket is compared with the base of a recycled bracket. The difference seen in the UV absorbance can be attributed to the presence of adhesive remnant. For each recycling procedure the difference in UV absorption is calculated. New stainless steel brackets and recycled brackets were tested for its shear bond strength with Instron testing machine. Comparisons were made between shear bond strength of new brackets with that of recycled brackets. The last part of the study involved correlating the findings of UV/Vis spectrophotometer with the shear bond strength for each recycling procedure. RESULTS: Among the recycled brackets the Sandblasting technique showed the highest shear bond strength (19.789MPa) and the least was shown by the Adhesive Grinding method (13.809MPa). CONCLUSION: The study concludes that sand blasting can be an effective choice among the 5 in house methods of recycling methods.

Evaluation of Effects and Effectiveness of Various α and ß Angulations for Three Different Loop Made of Stainless Steel Arch Wires - A FEM Study.

INTRODUCTION: Evaluations on retraction loop designs have been limited to describe the force systems applied to the buccal surfaces of the tooth that can be in different planes resulting undesirable effects, needing corrective action in future. By initially understanding these effects, modifications to the loop design can essentially counteract the undesired affects. AIM: To deter-mine Moments & M/F ratios produced by different gabling in the three retraction loops (Tear drop loop, T-loop, Open vertical loop) and movement of the anterior teeth and posterior teeth) of the maxillary arch in an extraction model, on activation of three retraction loops by1 mm. MATERIALS AND METHODS: A PC with Quad core processor, 8GB RAM, 1TB storage space and Graphic Accelerator was used. Computer Software: ANSYS Version11, PRO/ENGINEER was used in the study. The first step is modeling, done by using Pro/Engineer software and for creating a model the CT scan data is required. The maxilla with teeth of a patient is scanned at various sections at regular intervals of 0.5 mm. These scanned images are then imported into Pro/E software to various offset planes. Once imported, the software can do an automatic meshing and establishes contact automatically. RESULTS: When angulations increases intrusive or extrusive movements and movements in horizontal direction of crown tip and root tip increases. All values of T-loop are more than Teardrop loop and less than Open vertical loop. CONCLUSION: FEM study concludes that Teardrop loop with 10-20(α-ß) combination is preferred for Group A anchorage.

Elasticity in Elastics-An in-vitro study.

BACKGROUND: Orthodontic tooth movement results from application of forces to teeth. Elastics in orthodontics have been used both intra-orally and extra- orally to a great effect. Their use, combined with good patient co-operation provides the clinician with the ability to correct both anteroposterior and vertical discrepancies. Force decay over a period of time is a major problem in the clinical usage of latex elastics and synthetic elastomers. This loss of force makes it difficult for the clinician to determine the actual force transmitted to the dentition. It's the intent of the clinician to maintain optimal force values over desired period of time. The majority of the orthodontic elastics on the market are latex elastics. Since the early 1990s, synthetic products have been offered in the market for latex-sensitive patients and are sold as nonlatex elastics. There is limited information on the risk that latex elastics may pose to patients. Some have estimated that 0.12-6% of the general population and 6.2% of dental professionals have hypersensitivity to latex protein. There are some reported cases of adverse reactions to latex in the orthodontic population but these are very limited to date. Although the risk is not yet clear, it would still be inadvisable to prescribe latex elastics to a patient with a known latex allergy. To compare the in-vitro performance of latex and non latex elastics. MATERIALS & METHODS: Samples of 0.25 inch, latex and non latex elastics (light, medium, heavy elastics) were obtained from three manufacturers (Forestadent, GAC, Glenroe) and a sample size of ten elastics per group was tested. The properties tested included cross sectional area, internal diameter, initial force generated by the elastics, breaking force and the force relaxation for the different types of elastics. Force relaxation testing involved stretching the elastics to three times marketed internal diameter (19.05 mm) and measuring force level at intervals over a period of 48 hours. The data were analyzed with student independent - t test, analysis of variance and the Tukey - HSD test at p <0.05 level of significance. RESULTS: Non latex elastics had greater cross sectional area than latex elastics in all types of elastics. Forestadent heavy elastics had grater cross sectional area than GAC and Glenroe. There was no statistically significant difference in the internal diameter in between all type of elastics. Forestadent non latex elastics had greater breaking force compared to GAC and Glenroe elastics. Forces generated by the elastics decreased over 48 hours to an average load approximating 65-75% of the manufacturer's values. Force degradation was greater in non latex elastics compared to latex elastics. CONCLUSION: The results of the study demonstrated that the clinical choice of elastics should be based on the patient's medical history and the specific mechanical properties of the type of elastic. How to cite the article: Kamisetty SK, Nimagadda C, Begam MP, Nalamotu R, Srivastav T, Shwetha GS. Elasticity in Elastics-An in-vitro study. J Int Oral Health 2014;6(2):96-105.