Defect classification according to Schwarz et al.
| Class | Description |
| I | Intraosseous defects |
| Ia | Vestibular (oral vestibule) or oral dehiscence defects (defects due to divergence of associated tissue structures) |
| Ib | Vestibular or oral dehiscence defects with additional semicircular (“semicircular”) components |
| Ic | Vestibular or oral dehiscence defects with additional circular bone loss |
| Id | Circular bone resorption with oral and vestibular dehiscence defects. |
| Ie | Circular bone defects with preservation of vestibular and oral compacta |
| II | Horizontal supracrestal (“above the bone margin”) defects – The supracrestal distance here is measured between the peri-implant crestal alveolar bone (bone portion of the jaws in which the roots of the teeth are anchored) and the transition from the structured to the machined implant area. |
