Long-term stability of unilateral posterior crossbite corrected with function generating bite

Aim: The aim of this study was to evaluate the long-term stability of unilateral posterior crossbite correction after therapy with Function Generating Bite. Methods: 36 patients (17 boys and 19 girls, 8,53 ± 2 y.o.) with unilateral posterior crossbite corrected with Function Generating Bite were included in this study. Linear measurements were made on dental casts by the same examiner with a digital gauge considering the intermolar distance between the tips of cusps (mesiobuccal cusp was used) and the shortest intermolar distance at the gingival crests. In 21 patients, when the deciduous canines were present, the mean intercanine distances at tips of cusps and at gingival crests were registered. Measurements were made before treatment (T0), after crossbite correction (T1), and about 3 years after the correction and the end of active treatment (T2). Results: The results showed that: before therapy mean intermolar distance was 45.2 mm (±9) at tips of cusps and 29.52 mm (±7) at gingival crests, intercanine distance was 28.93 mm (±2) and 20.65 mm (±2). After crossbite correction mean intermolar distance was 50.2 mm (± 10) at tips of cusps (p= 0.002) and 32.39 mm (±7) at gingival crests (p= 0.007). Intercanine distance was 31.33 mm (±2) at tips of cusps (p=0.03) and 23.2 mm (±2) at gingival crests (p=0.0001). About 3 years after the end of active treatment, mean intermolar distance was 52.71 mm (±3) at tips of cusps (p=0.0004) and 35.71 mm (± 4) at gingival crests (p=0.0006), intercanine distance was 32.83 mm (±2) (p=0.02) and 24.04 mm (±2) (p=0.0003). The mean increase of maxillary transversal widths during treatment (T1-T0) in the intercanine distance was 2.39 mm (±1) at the tips of cusps and 2.55 mm (±1) at gingival crest , whereas in the intermolar distance was 4.50 mm (±1) at the tips of cusps and 3.27 mm (±1) at gingival crest. The study showed an additional increase of transversal widths before correction (T1-T2): the mean increase in intercanine distance was 1.5 mm (±1) at the tips of cusps and 0.84 mm (±1) at gingival margin, in the intermolar distance was 0.99 mm (±1) at the tips of the cusp and 0,87 mm (±1) at gingival crest. The overall increase (T0-T2) of intercanine and intermolar distance was 3.89 mm (± 1) and 5.5 mm (±1) at the tips cusps, 3.39 mm (±1) and 4.48 mm (±1) at the gingival crest. Conclusion: The increase of maxillary transversal width in patients with unilateral posterior crossbite corrected by Function Generating Bite was significant and showed higher values compared to results in literature using fixed appliances. Moreover, at 3 years follow-up, patients treated with Function Generating Bite significantly showed an additional increase of intercanine and intermolar distance instead of the relapse showed after use of fixed appliance in literature.