Zygomatic miniplates produced measurable open-bite correction without orthognathic surgery
Adult skeletal anterior open bite remains one of the most difficult orthodontic problems because growth modification is no longer an option once skeletal maturity has been reached. Conventional incisor extrusion can close the bite, but it often does so at a cost: the lower face can lengthen further, and relapse is a familiar concern when the underlying vertical discrepancy is not controlled. In this prospective interventional case series, bilateral zygomatic miniplates were used as skeletal anchorage to intrude maxillary molars and redirect the bite relationship in 20 adults treated at two centers in Saudi Arabia.
The cohort was small, but the treatment effect was not subtle. Mean overbite shifted from −6.0 ± 1.48 mm before treatment to 2.80 ± 0.78 mm at 12 months, a correction of 8.80 ± 1.26 mm. Overjet also improved, falling from 6.05 ± 1.08 mm to 2.67 ± 0.63 mm. These changes matter because anterior open bite is not only a cosmetic or speech issue; it reflects a vertical skeletal imbalance that often resists ordinary tooth movement unless the posterior dentoalveolar excess is controlled first.
Posterior intrusion drove the bite closure
The mechanics were straightforward and biologically plausible. After bilateral miniplate placement under local anesthesia, fixed orthodontic treatment used a modified Erverdi appliance together with nickel-titanium coil springs delivering 150–200 g of force per side. The goal was maxillary molar intrusion, and the measured response aligned closely with that intent. True intrusion of the maxillary first molars averaged −3.0 ± 0.86 mm relative to the palatal plane.
One sentence captures the treatment logic: posterior intrusion altered the mandibular posture enough to close the anterior gap.
As the molars moved superiorly, the mandible rotated counterclockwise. That rotation reduced the Frankfort-Mandibular plane angle, which fell from 31.95 ± 1.81° to 29.12 ± 1.71° by 12 months, a mean reduction of 2.8 ± 0.89°. In adult open-bite correction, this is the key anatomical lever. Rather than forcing the incisors to compensate for a vertical skeletal problem, the therapy addressed the posterior height excess that often keeps the mandible open and the bite separated.
Skeletal anchorage gave the orthodontist a firmer biomechanical foothold
The study enrolled consecutive adults between 16 and 28 years of age, including 12 females and 8 males, with skeletal maturity confirmed by cervical vertebral maturation stage CS5–CS6. Inclusion criteria were specific: open bite between −4 mm and −8 mm, maxillary posterior vertical dentoalveolar excess, acceptable incisor-lip relations, and Frankfort-Mandibular plane angle greater than 29°. Those parameters define a population in which pure dental camouflage is unlikely to be enough, but full orthognathic surgery may be more than some patients want or need.
Skeletal anchorage changes the biomechanics in a meaningful way. Conventional orthodontic anchorage depends on teeth, which can move or tip in response to force. A miniplate fixed to bone offers a more stable platform, allowing intrusive force to be applied to the molars with less unwanted reciprocal movement. In an open-bite case, that stability can translate into more predictable posterior height reduction and a more reliable mandibular autorotation pattern.
The statistical associations in this cohort fit that model. Correlation between molar intrusion and overbite correction was strong, with ρ = 0.85. The relationship between molar intrusion and FMA reduction was moderate, with ρ = 0.72. Those values do not prove causation, but they do reinforce the mechanical chain linking posterior intrusion, mandibular rotation, and anterior bite closure.
Safety signals were clean over 12 months
No plate loosening, infection, or relapse was observed during follow-up. In a small cohort, that absence of complications cannot be interpreted as proof of universal safety, yet it is still clinically relevant. Zygomatic miniplates are placed in a region that allows relatively robust anchorage, and their use under local anesthesia may lower the procedural burden compared with more invasive jaw surgery. For patients who meet the skeletal criteria but are reluctant to undergo orthognathic correction, that balance of efficacy and invasiveness is the central appeal.
The operative pathway also matters for adherence. Adults with open bite often endure prolonged treatment, and a method that produces visible occlusal change without major surgery may improve acceptance of definitive care. The present study did not measure patient-reported outcomes, treatment burden, or quality of life, so those practical dimensions remain outside the evidence base here.
What the data can and cannot support
The findings support zygomatic miniplate anchorage as a workable option for correcting adult skeletal anterior open bite when posterior maxillary excess is part of the problem. Overbite, overjet, and FMA all improved across the 12-month observation window, and the magnitude of overbite correction was substantial. The treatment effect also followed a coherent anatomical pathway: molar intrusion led to counterclockwise mandibular autorotation and a narrower open-bite gap.
The evidence still comes from a single-arm case series of 20 patients, which leaves important questions unanswered. Without a control group, the study cannot separate the specific contribution of the miniplates from other concurrent orthodontic effects. The follow-up period was limited to 12 months, so long-term stability after appliance removal remains unknown. Comparative data against other temporary anchorage devices, or against orthognathic surgery in similarly selected adults, are not available from this cohort.
Even with those limits, the study offers something useful to orthodontic practice: a documented route to skeletal open-bite correction that avoids jaw surgery while preserving posterior vertical control. For adults with completed growth and a genuine skeletal discrepancy, that combination is clinically attractive. The next step is not speculation but comparison—longer follow-up, larger samples, and controlled trials that can determine how durable miniplate-assisted intrusion really is when the appliances come off.