Rg. Craig et Rz. Legeros, Early events associated with periodontal connective tissue attachment formation on titanium and hydroxyapatite surfaces, J BIOMED MR, 47(4), 1999, pp. 585-594
Endosseous dental implants can support at least three types of biomaterial/
connective tissue interfaces: osseointegration, fibro-osseous integration,
and periodontal connective tissue attachment. Although a periodontal connec
tive tissue attachment offers distinct advantages, only osseointegration an
d fibro-osseous integration are at present clinically achievable. Recent st
udies indicate a periodontal regeneration-competent cell population and an
appropriate biomaterial substrate both are required for periodontal connect
ive attachment formation on biomaterial surfaces. We therefore have develop
ed an in vitro model to characterize the effects of various biomaterial sub
strates on the early events of periodontal connective tissue attachment for
mation. Primary cultures of periodontal ligament and gingival connective ti
ssue cells were cultured on uncoated (control) and coated (titanium- and hy
droxyapatite-coated) tissue culture plastic, and the level of cell prolifer
ation, collagen, and noncollagen protein synthesis, alkaline phosphatase ac
tivity, and expression of a 42 kD cementum extracellular matrix protein wer
e measured over 5, 7, and 9 days in culture. While all three substrates sup
ported cell attachment, proliferation, and protein synthesis, only uncoated
and titanium-coated tissue culture plastic supported expression of the cem
entum extracellular matrix protein after 9 days of culture. In addition, th
e levels of cell proliferation and collagen and noncollagen protein synthes
is for cells grown on hydroxyapatite-coated surfaces lagged behind cells cu
ltured on the control or titanium-coated surfaces at each of the three time
points. These data suggest that biomaterial substrates markedly can influe
nce the temporal sequence of extracellular matrix proteins associated with
periodontal connective tissue attachment formation. In addition to surface
composition (titanium versus hydroxyapatite), surface properties (e.g., top
ography) also may have an effect on periodontal connective tissue attachmen
t formation. This model may be of use in designing biomaterials to support
the formation of periodontal connective tissue attachment in vivo. (C) 1999
John Wiley & Sons, Inc.