| Class I |
a |
Combined horizontal and vertical loss of the adjacent vestibular alveolar bone, leading to a dehiscence-type defect. |
| b |
Higher dehiscence values than Class Ia defects and clearly identifiable mesial and distal circumferential component. |
| c |
Additional circumferential component measured as the linear mid-oral distance from the implant surface to the inner surface of the alveolar bone components, without resulting in a dehiscence-type defect on the oral aspect. |
| d |
Clear mesial and distal component with oral and vestibular dehiscence. |
| e |
Clear mesial, distal, vestibular, and oral component without a dehiscence-type defect. |
| Class II |
|
Consistent horizontal bone loss, identifiable as supra-alveolar exposition of the implant. |
