Over-insertion of orthodontic mini-implants in the maxilla: A systematic review of maxillary sinus, nasal floor and incisive canal perforations.

OBJECTIVE: Orthodontic mini-implants (OMIs) provide skeletal anchorage but may be over-inserted, perforating the maxillary sinus, nasal cavity, or incisive canal. This systematic review evaluated the frequency and consequences of such over-insertion in the maxilla. METHODS: This systematic review was registered in PROSPERO (CRD420261377587) and followed PRISMA guidelines. PubMed, Livivo, Cochrane, and Google Scholar were searched for studies reporting prevalence and complications of maxillary OMI over-insertion. Of 98 records, 7 studies were included. Two reviewers independently selected and extracted data, and methodological quality was assessed using Joanna Briggs Institute tools. RESULTS: Across the included studies comprising 702 OMIs, maxillary sinus perforation ranged from 8 to 78.3%, with mean penetration depths between 0.79 and 3.23mm. In a cadaver model, sinus perforation increased from 0% with 6-mm screws to 10% with 8-mm and 15% with 10-mm screws. Penetration>1mm raised Schneiderian membrane thickening from 37.5 to 88.2%, with a mean increase of 0.6mm, but no clinical sinusitis was reported. A sinus floor thickness<6mm markedly increased penetration risk (odds ratio 21.63). For anterior palatal OMIs, incisive canal perforation affected 25% of subjects (13.5% of OMIs), and nasal floor perforation up to 21.2% of subjects (11.5% of OMIs), with mean depth 1.4±0.4mm (range 0.5-2.0mm). One oronasal fistula after osseointegrated palatal implant explantation was the only severe complication. CONCLUSIONS: Radiographic perforations are relatively frequent, and risk is influenced by sinus floor thickness, screw length, insertion angle, age, and anterior crowding. Although these perforations are usually clinically asymptomatic, cautious length selection and 3D-based planning are recommended to minimize avoidable tissue reactions.