Vertical bone augmentation at endosseous implants is a technically challenging procedure that, when successful, can contribute to the biomechanical and
esthetic value of implant-supported dental rehabilitations. One approach is the creation of a protected space for host cell ingrowth and subsequent bone
formation. The aim of this pilot study performed in the beagle dog model was to examine the feasibility of an alternative approach for concurrent implant
placement and vertical bone augmentation using an allogeneic marrow-derived stem cell-based construct without a barrier membrane. Allogeneic
marrow-derived stem cells were obtained from iliac crest aspirations from donor animals and subsequent cell culture expansion. Alveolar defects (7
mm long x 4 mm deep) were created six weeks following tooth extraction. Central to the defects, 3.5 x 8 mm endosseous implants were placed at a
depth of 4.5 mm. The 3.5 mm of exposed implant was either a) left exposed to the forming blood clot, b) covered with a HA/TCP matrix, c) covered
with an allogeneic-stem cell-loaded matrix or d) covered with an autogenous bone graft. After 6 weeks, block sections of the mandible were prepared
for histological evaluation of healing. For each implant (2 per test group), three sections were made parallel with the long axis of the implants. The
histological appearance of bone was scored for each dental implant at both the implant-host bone interface and the implant-regenerated bone interface.
The results demonstrated that allogeneic stem cell-loaded devices supported the formation of a bone-to-implant interface along the entire vertical
augmentation surface of the implants and along the bone-to-graft interface. Vertical augmentation was also achieved using autogenous bone. However,
in the absence of allogeneic stem cells or in the absence of any matrix graft, bone regeneration failed to occur. This initial success with vertical alveolar
bone augmentation at dental implants using an MSC-based tissue engineering approach suggests a number of avenues to improve or simplify current
regenerative therapies in dentistry.
Author(s): Luisa F. Echeto, Ingeborg J. De Kok, Debra Sacco, Susan J. Drapeau, and Lyndon F. Cooper