Marginal bone loss around mandibular implant depends on all except
Abutment
Boning technique
Connector
Implant fixture
Bone loss around Implant-

One of the primary complications
Abnormal if more than 0.2mm/year
For peri-implantitis 1 mm to 1.5 mm detectable bone loss recommended

Important factors on which bone loss depends around an implant-

Implant size and shape (improper)
Inadequate in number compare to desired
Wrong positioning
Bone quality already poor or amount is inadequate
Initial instability achieved
Compromised healing phase
Improper prosthesis fit like Implant fixture
Defective design (like excessive cantilever, poor hygiene access)
Non maintained or excessive occlusal forces
Improper fitting of abutment components
Poor oral hygiene
Some systemic conditions like uncontrolled diabetes
Poor oral habits like tobacco chewing, smoking