Understanding peri-implant endosseous healing

932 Journal of Dental Education ■ Volume 67, Number 8
Transfer of Advances in Sciences into Dental Education
Understanding Peri-Implant Endosseous
Healing
John E. Davies, B.D.S., Ph.D., D.Sc.
Abstract: If dental implantology is an increasingly successful treatment modality, why should we still need to understand the
mechanisms of peri-implant bone healing? Are there differences incortical and trabecular healing? What does “poor quality”
bone mean? What stages of healing are most important? How do calcium phosphate-coated implants accelerate healing? What is
the mechanism of bone bonding? While there are still many aspects of peri-implant healing that need to be elucidated, it is now
possible to deconvolute this biological reaction cascade, both phenomenologically andexperimentally, into three distinct phases
that mirror the evolution of bone into an exquisite tissue capable of regeneration. The first and most important healing phase,
osteoconduction, relies on the recruitment and migration of osteogenic cells to the implant surface, through the residue of the
peri-implant blood clot. Among the most important aspects of osteoconduction are the knock-oneffects generated at the implant
surface, by the initiation of platelet activation, which result in directed osteogenic cell migration. The second healing phase, de
novo bone formation, results in a mineralized interfacial matrix equivalent to that seen in the cement line in natural bone tissue.
These two healing phases, osteoconduction and de novo bone formation, result in contact osteogenesisand, given an appropriate
implant surface, bone bonding. The third healing phase, bone remodeling, relies on slower processes and is not considered here.
This discussion paper argues that it is the very success of dental implants that is driving their increased use in ever more challeng-
ing clinical situations and that many of the most important steps in the peri-implant healing cascadeare profoundly influenced by
implant surface microtopography. By understanding what is important in peri-implant bone healing, we are now able to answer all
the questions listed above.
Dr. Davies is Professor, Bone Interface Group, Faculty of Dentistry and Institute for Biomaterials and Biomedical Engineering,
University of Toronto, 4 Taddle Creek Road, Toronto, Ontario, Canada M5S 3G9;416-978-1471 phone; 416-946-5639 fax;
davies@ecf.utoronto.ca.
Key words: bone, healing, formation, osteoconduction, platelets, “poor quality bone,” osteogenic cells, osteoblasts, calcium
phosphates, titanium, implants
Submitted for publication 4/28/03; accepted 5/30/03
I
t is just as true in dentistry as in other disciplines
that the more useful a technology, the more rap-
idly are itslimits challenged by the user and that,
in turn, user demand drives the necessity for refine-
ments and improvements in the technology. An ob-
vious example would be the rapid evolution of com-
puters over the last few decades that has led to our
almost indispensable reliance on the ubiquitous mi-
crochip. Similarly, in dentistry, over the last few de-
cades there has been anincreasing use of endosseous
(in-bone) implants as a means of providing a foun-
dation for intra-oral prosthetic devices,1 from full arch
dentures to single crowns, or other devices for orth-
odontic anchorage2,3 or distraction osteogenesis.4,5
While there is no question that the popularity of
endosseous implants for these treatment modalities
is based on increasingly convincing data oflong-term
clinical success rates, it is this very success that has
prompted the use of implants in more challenging
clinical situations than were previously envisioned.6
Thus, single root implants previously employed
in only anterior mandibular and maxillary sites are
now commonly inserted into posterior regions where
there is less cortical bone to provide initial mechani-
cal...