What causes initial crestal bone loss from implant surgery?
Crestal bone loss from an implant surgery is inevitable. Some of the bone will die from the trauma of the surgery. Where and how much is not totally in our control, but we can to some extent predict high risk areas. Note the crestal bone loss we are discussing is not the same as the bone one loses from peri-implantitis or natural bone loss. This bone loss occurs during the initial healing phase.
What is the cause of the bone loss?
Trauma, or more precisely the interference and destruction of oxygenated blood flow to the area, is the cause. This occurs in the crestal area because cortical bone has a lower blood supply and fewer osteoprogenitor cells in comparison to the trabecular bone. Kristensen 2014 AJPath Cortical crestal bone has the highest strain levels during dental implant surgery yet is the most sensitive to bone loss. Pikos Comp 2019 ref 10 and 11. This is a recipe to guarantee some crestal bone loss.
What areas of are more at risk for bone loss from the dental implant surgery?
Cortical bone is at high risk of being lost because it starts with a much lower blood supply. Therefore, people with thick cortical bone are at higher risk.
Areas of bone with low blood supply are at higher risk of crestal bone loss. There could be many reasons someone has low blood supply to the bone, such as radiation treatment.
Areas that are more traumatized and have lost more blood supply are at higher risk. This is why flapping causes more bone loss as the bone loses the blood supply from the periosteum.
Thin bone is at higher risk because it is more likely to be all cortical bone and there will be even less blood supply in thinner bone.
Areas of very dense bone are at higher risk.
How can we limit the changes in bone from occurring?
Know the anatomy of the area, and particularly the thickness of the cortical bone, ahead of time will help you know your risks. High insertion torques in areas of thick cortical bone will increase the likelihood of crestal bone loss. Simons COIR 2015 recommends bone tapping to help prevent high insertion torques at sites with thick cortical bone.
If a osteomy site has no bleeding in it at all there are clinicians who recommend letting the area heal for 2-4 weeks and then coming back and placing the implant. This makes a lot of sense but does require a second visit which no one wants.