No abstract

Objectives: The aims of this study were to compare the efficacy of two proven chemical disinfectants, glutaraldehyde and povidone iodine on dental impression and models by determining the reduction in the microbial load, and to compare changes in the physical properties of the models after adding the disinfectants. Materials and Methods: Irreversible hydrocolloid upper impressions of 90 patients were made and divided into 3 groups of 30 samples each; Group A––Control group; Impressions were run under clean tap water before pouring the model. Group B––2% Glutaraldehyde sprayed on the impression and left in situ for 10 min before pouring the model. Group C –10 ml of (5%) povidone iodine incorporated into the gypsum before pouring the model. Models from all three groups were subjected to microbiological assessment at three different time intervals, T0––24 h, T1––1 month and T2––3 months of storage by comparing the colony forming units (CFUs) of bacteria and fungi. The compressive strength of 5 models from each group was also analyzed in Newton's/mm2. Results: 2% Glutaraldehyde proved more effective than povidone iodine after 24 h of storage (T1), however at the end of 1 month (T1) and 3 months (T2) the Povidone group showed the maximum disinfection. Both the disinfectants caused a reduction in the compressive strength of the model with the povidone iodine group showing the maximum reduction. Conclusion: Although povidone iodine was the most effective disinfectant after 3 months, it showed a significant reduction in the compressive strength and caused discoloration of the model. 2% Glutaraldehyde proved to be the choice of disinfectant with minimal adverse effects.

Aim: This study aims at comparing the transverse width changes during leveling and aligning phase with conventional and self-ligating brackets. Materials and Methods: The study consisted of twenty samples. The sample was split into two groups. Group 1 consisted of ten samples treated with conventional brackets and ten samples treated with self-ligating brackets. Pretreatment and leveling aligning cast were used for the study. Measurement of transverse dimension was taken at two different regions, premolar and molar. Reference points were chosen according to the Pont's model analysis. In the premolar region, measurements were made from the distal pit of the first premolar on either side, and in the molar region, measurements were made from the mesial pit on either side. The overall values are compiled and compared among both the bracket groups. Results: The results of the study showed that there were changes in the interpremolar and intermolar arch width during leveling and aligning phase in both the bracket types. Conclusion: Since the arch width changes can affect the stability in the posttreatment phase, an orderly use of custom-made archwires from the very beginning is advised. The amount of arch width changes that occur with the treatment is irrespective of the bracket type, provided that other factors are maintained to be constant. Both conventional metal-ligated brackets and dual-activation self-ligating brackets provide an equal amount of changes in the dental arch transverse dimensions.