Comparative Evaluation of Primary Stability of Two Different Types of Orthodontic Mini-Implants.

Background: The mini-implants introduced new possibilities of adequate anchorage in orthodontics. Furthermore, due to its small size, it can even be placed at relatively difficult sites with ease. Removal torque should be high to prevent implant unscrewing. Objective: This prospective clinical trial was aimed to evaluate the insertion torque and removal torque of single-threaded and double-threaded cylindrical orthodontic mini-implants. Materials and Methods: A total of 36 cases were randomly divided into two groups, with an equal number of patients in each group (n = 18). In Group 1 single-threaded cylindrical mini-implant was placed, and in the other group, cylindrical implants with double-threaded were placed. Maximum insertion torque (MIT) and maximum removal torques (MRTs) were recorded for both groups. Data collected were subjected to statistical analysis. Results: MIT was found to be significantly higher than MRT for both the groups and between the groups. Intergroup comparison in the present study showed significantly higher values for MIT than MRT. Intergroup comparison of MIT showed more values for Group 2 as compared to Group 1. Similar statistically significant values were seen in terms with MRT, where double-threaded cylindrical mini-implants had more torque value than the other group. Conclusions: Orthodontic mini screws represent effective temporary anchorage devices. Double-threaded cylindrical mini-implants have significantly higher insertion and removal torque than single-threaded mini-implants and hence better stability. [ABSTRACT FROM AUTHOR]