Management of skeletal anterior open bite using zygomatic miniplates: a prospective interventional study

Apertognathia (anterior open bite) is among the most challenging skeletal discrepancies in adult orthodontics, where growth modification is no longer feasible. Orthognathic surgery is effective but invasive, whereas conventional incisor extrusion increases lower facial height and is prone to relapse. This study evaluated the clinical and cephalometric outcomes of managing anterior open bite using a zygomatic miniplate skeletal anchorage system combined with fixed orthodontic appliances. This single-arm prospective interventional study (case series) was conducted at the Gurayat Specialist Dental Center and Gurayat General Hospital, Al-Qurayyat, Saudi Arabia, from February 2023 to January 2024. Twenty consecutively enrolled adult patients (12 females, 8 males; mean age 20.85 ± 3.18 years; range 16–28 years) with skeletal anterior open bite were treated. Inclusion criteria were an open bite of − 4 mm to − 8 mm, maxillary posterior vertical dento-alveolar excess, acceptable incisor-lip relations, and a Frankfort-Mandibular plane angle (FMA°) greater than 29°. Skeletal maturity was confirmed using the cervical vertebral maturation (CVM) method (stage CS5–CS6) prior to inclusion. All patients underwent bilateral zygomatic miniplate placement under local anaesthesia, followed by fixed orthodontic treatment with a modified Erverdi appliance. Maxillary molar intrusion was performed with nickel-titanium coil springs delivering 150–200 g of force per side. Cephalometric variables (overbite, overjet, FMA°, and true molar intrusion) were recorded at pretreatment (T1), 6 months (T2), and 12 months (T3). Because the Shapiro–Wilk test indicated non-normal distributions for several variables, non-parametric tests (Wilcoxon Signed-Ranks and Kruskal–Wallis) were used throughout, with Spearman correlation; significance was set at p < 0.05. Significant improvements were observed across all parameters. Mean overbite improved from − 6.0 ± 1.48 mm (T1) to 2.80 ± 0.78 mm (T3) (correction 8.80 ± 1.26 mm; 95% CI 8.21–9.39 mm). Overjet decreased from 6.05 ± 1.08 mm to 2.67 ± 0.63 mm (reduction 3.37 ± 0.8 mm). True intrusion of the maxillary first molars averaged − 3.0 ± 0.86 mm relative to the palatal plane, with a mean FMA° reduction of − 2.8 ± 0.89° (from 31.95 ± 1.81° to 29.12 ± 1.71°). A strong correlation was found between molar intrusion and overbite correction (ρ = 0.85) and a moderate correlation with FMA° reduction (ρ = 0.72). No plate loosening, infection, or relapse was observed during follow-up. Within the limitations of a small, single-arm sample and a 12-month follow-up, zygomatic miniplate anchorage combined with fixed appliances appears to be an effective, minimally invasive option for correcting skeletal anterior open bite in adults. The approach induces counterclockwise mandibular autorotation and improves overbite, overjet, and FMA° without orthognathic surgery. Longer-term, controlled studies are required to confirm stability and to compare miniplates with alternative anchorage devices.