Infrazygomatic Crest: Bone Screws- A Review

Abstract

Infrazygomatic crest (IZC) bone screws have gained widespread acceptance as an extra-alveolar skeletal anchorage system in orthodontics. Their strategic placement in the dense cortical bone of the infrazygomatic region allows clinicians to perform complex orthodontic movements with minimal reliance on dental anchorage or patient compliance. IZC bone screws are particularly advantageous for maxillary distalization, intrusion mechanics, and vertical control in patients with skeletal discrepancies. This review comprehensively discusses the anatomical considerations, screw design, biomechanical principles, clinical indications, placement protocols, success rates, complications, comparative advantages, and future perspectives of IZC bone screws, supported by current scientific evidence.

Introduction

Anchorage control is essential in orthodontic treatment, and the introduction of temporary anchorage devices (TADs) has significantly improved treatment efficiency by providing stable anchorage independent of patient compliance. Infrazygomatic crest (IZC) bone screws represent an important advancement among TADs due to their extra-radicular placement, which avoids root interference, allows higher orthodontic forces, and enables more versatile tooth movement.

The infrazygomatic crest offers dense cortical bone suitable for stable screw placement, typically 12–17 mm above the maxillary occlusal plane. Although proximity to the maxillary sinus is a concern, limited sinus penetration does not significantly affect success when adequate cortical engagement is achieved. IZC bone screws are commonly made of titanium alloy or stainless steel, with design features such as increased length, appropriate diameter, and self-drilling threads contributing to primary stability.

Biomechanically, IZC screws rely on mechanical retention rather than osseointegration. Oblique insertion angles enhance cortical contact and reduce stress, while the extra-alveolar position permits force application closer to the center of resistance, improving bodily tooth movement and minimizing unwanted effects.

Clinically, IZC bone screws are widely used for maxillary arch distalization, vertical control through posterior intrusion, and anchorage in complex orthodontic mechanics. Their use can reduce the need for extractions and improve facial esthetics. CBCT imaging and digital planning have improved placement accuracy and safety.

Reported success rates range from 75% to 95%, with failures mainly associated with poor oral hygiene, inflammation, and inadequate cortical engagement rather than patient age or minor sinus perforation. Compared to interradicular miniscrews, IZC screws provide greater freedom of movement but require advanced anatomical knowledge and precise technique. Future developments are expected to focus on AI-assisted planning, customized screw designs, and standardized clinical protocols.

Conclusion

Infrazygomatic crest bone screws provide a reliable, versatile, and efficient skeletal anchorage system in orthodontics. Their ability to support complex orthodontic mechanics with high success rates makes them a valuable tool in contemporary practice. Proper case selection, imaging, and biomechanical planning are essential for achieving predictable outcomes.

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Copyright

Copyright © 2026 Dr. Lokesh Kumar, Dr. Loga Priya, Dr. R. Sukanya, Dr. S. Keerthana, Dr.Jeevana . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.