Edentulous jaw segment parameters Edentulous jaw segment types (risk degree)
Type I
(low risk)
Type II
(moderate risk)
Type III
(high risk)
Non aesthetic zone
Height (mm) Maxilla > 10 > 8 to ≤ 10 > 4 to ≤ 10 in MSR ≤ 8 ≤ 4 in MSR
Mandible > 10 > 8 to ≤ 10 ≤ 8
Width (mm) > 6 > 4 to ≤ 6 < 4
Length (mm) ≥ 7 or ≤ 12 ≥ 6 or ≤ 13 < 6 or > 13
Alveolar ridge vertical position (mm) ≤ 3 > 3 to < 7 ≥ 7
Aesthetic zone
Height (mm) Maxilla > 10 > 8 to ≤ 10 > 4 to ≤ 10 in MSR ≤ 8 ≤ 4 in MSR
Mandible > 10 > 8 to ≤ 10 ≤ 8
Width (mm) Optimal implant diameter + 3 Optimal implant diameter + < 3 Optimal implant diameter + ≤ 0
Length (mm) Equal to contralateral tooth Asymmetry with contralateral tooth < 1 Asymmetry with contralateral tooth ≥ 1
Alveolar ridge vertical position (mm) ≤ 1 > 1 to ≤ 3 > 3
Interdental bone peak height (mm) Mesial 3 to 4 ≥ 1 to < 3 < 1
Distal 3 to 4 ≥ 1 to < 3 < 1
MC region (IAN injury risk degree)
MC walls identification and jawbone
quality typea combination
Identified MC walls/D2
and D3
Unindentified superior
MC wall/D1 and D4
Unindentified MC/D1 and D4

aD = bone quality defined according to Lekholm and Zarb (1985).
MC = mandibular canal; IAN = inferior alveolar nerve; MSR = maxillary sinus region.