An extra short, 2-piece implant with a Brånemark hexagon interface was developed with a bone anchoring length of only 4.5 mm, for subjects with severely resorbed jaws.

Inclusion Criteria:

• The subject should be at least 18 years of age and have passed secession of growth
• The subject should be in need of an implant-supported restoration in the posterior region of the mouth (maxilla: first premolar to third molar, mandible: first premolar to second molar, not third molar due to mobile gingiva), where at least 2 implants are needed of which at least one should be an Extra Short Implant
• Obtained informed consent from the subject
• The subject must be in such a physical and mental condition that a 5-year follow-up period can be carried out without foreseeable problems
• The subject should have a severely resorbed posterior mandible and/ or maxilla.
• Implants are only to be placed in healed sites, defined as a site with minimum 6 months of healing following tooth extraction
• At least 6 mm residual bone width, between 4-7 mm residual bone height in the maxilla and between 6-9 mm residual bone height in the mandible
• At implant installation the implant should be stable; final tightening torque of the implant about 25 Ncm or higher, preferably not exceeding 45 Ncm
• The subject should be healthy and compliant with good oral hygiene
• Favorable and stable occlusal relationship

Exclusion Criteria:

• The subject is not able to give her/his informed consent of participating
• Health conditions, which do not permit the surgical treatment
• Reason to believe that the treatment might have a negative effect on the subject's total situation (psychiatric problems), as noted in subject records or in subject history
• Any disorders in the planned implant area such as previous tumours, chronic bone disease or previous irradiation
• Alcohol or drug abuse as noted in subject records or in subject history.
• Heavy smoking (>10 cigarettes/day)
• Intake of medication containing bisphosphonates
• Uncontrolled diabetes, i.e. a subject with diagnosed diabetes that has a history of neglecting doctor's recommendations regarding treatment, food and alcohol intake
• Severe bruxism or other destructive habits
• Immediate insertion (i.e. placement of the implant immediately after extraction)
• Bone augmentation procedures before or at implant installation is not allowed
• Deviation from stated drilling protocol, utilizing osteotomes, is not allowed
• Lack of opposing dentition
• Single crown restorations are not to be performed in the study