Investigation Of The Effects Of Twin-Block Appliances On Demineralization Of Lower First Premolar

Objective: The purpose of this study is to evaluate possible mineral losses in mandibular first premolars after the use of twin-block appliance, by enamel microhardness measurement method. Materials and Methods: Twenty patients (12 females, 8 males; mean age=12.21±1.12) indicated as fixed orthodontic treatment with mandibular first premolar extraction after functional treatment with twin-block were included in the study. The twin-block appliance was used continuously (excluding meals) for 12 months. The appliance used in this research, which is a split-mouth study, was designed to cover the first premolar only on one side of the mandible, leaving the opposite the first premolar tooth exposed. After the extraction of the mandibular first premolars, two groups were formed: the teeth outside the appliance (Group I) and the teeth inside the appliance (Group II). Hardness measurements were calculated using Vicker’s microhardness measuring device on the buccal and lingual regions of the both groups. 200 g load was applied to specimens for 10 sec. Two Independent Sample t test used in the statistical analysis of the data. Results: A statistically significant difference was found between the hardness values of the buccal and lingual tooth regions of Group I and Group II (p <0.05). Group II showed statistically significantly lower hardness values on both tooth regions (buccal region and lingual region) than Group I. In both groups, the hardness values on the buccal regions of the teeth were found to be significantly lower than the hardness values on the lingual regions (p <0.05). Conclusion: There is a possibility of mineral loss in the teeth remaining inside the appliance in treatments using the twin-block appliance