CONCLUSION
The results of the study indicate that there is no significant difference on the health of periodontium between the FRC and MSW fixed retainers, therefore, the null hypothesis was accepted. Both types of mandibular retainers can be used alternatively. Mandibular fixed lingual retainers deteriorate the health of periodontium; therefore, routine checkup visits should be planned.  Patients displayed in this article previously approved the use of their facial and intraoral photographs.