Salivary insulin-like growth factor-1 (IGF-1) and bone alkaline phosphatase (BALP) levels during mandibular advancement with Twin Block appliance: A longitudinal study.

OBJECTIVE

To assess salivary insulin-like growth factor-1 (IGF-1) and bone alkaline phosphatase (BALP) levels during mandibular advancement with Twin Block appliance.

METHODS

The study enrolled 49 participants with skeletal Class 2 malocclusion, a retrognathic mandible, positive visual treatment objective (VTO), horizontal to average growth pattern and cervical vertebrae maturation index stages 3-4 (CVMI). Participants were treated with Twin Block appliance (Twin Block group [TBG]; n = 39). Salivary samples were collected before treatment (T0), at 7-10 days (T1), 6-10 weeks (T2), 8-10 months (T3) and after treatment (T4). Non-compliant participants formed the non-compliant group (NCG; n = 10). Lateral cephalograms were obtained for cephalometric evaluation. Statistical analyses compared salivary IGF-1 and BALP levels and cephalometric parameters within and between groups.

RESULTS

The final sample included 39 participants in the TBG (17 boys, 22 girls; mean age =12.56 ± 1.09 years) and 10 participants in the NCG (5 boys, 5 girls; mean age =12.7 ± 1.16 years). A significant difference was observed in the salivary IGF-1 and BALP levels within the TBG across different time intervals. In the TBG, IGF-1 increased significantly at T1, and BALP significantly increased at T2 and T3. The NCG showed no significant changes in levels of IGF and BALP. A significant positive correlation between IGF-1 and BALP was noted at T1 in the TBG (P <0.05), whereas a significant negative correlation was observed at T2 and T3 (P <0.05). Mann-Whitney test showed a significant increase in mandibular length in TBG compared to NCG. Cephalometric analysis revealed significant improvements in mandibular length in TBG compared to NCG between T0 and T4.

CONCLUSIONS

The study demonstrated a significant increase in salivary IGF-1 levels within 7-10 days, with BALP levels peaking at 6-10 weeks. These findings suggest a potential role of IGF-1 and BALP in the biochemical response to Twin Block appliance therapy.