Objectives: To evaluate the effectiveness of lingual arch in maintain space in children who lost teeth early. Subjects and methods: 30 children with missing mandibular primary molars were included in this study. The authors conducted a prospective, descriptive study and compare the effectiveness before-after treatment. Results: With lingual arch, the mean of space lost is 0.51+/- 0.38mm, 0.8+/-0.51mm after 3 months and 6 months, respectively. The effectiveness of using lingual arch after 3months: Good: 86.7 percent, Moderate: 13.3 percent
and after 6months is: Good: 70 percent, Moderate: 23.3 percent
Bad: 6.7 percent.