Biomedical Engineering Reference
In-Depth Information
was reduced to make space for a previously fabricated calcium
orthophosphate cement block. One more month later, 8 mm HA
implants were placed in such a manner that the apical half was
embedded into alveolar bone and the coronal half in the calcium
orthophosphate cement block. The investigators observed that the
cement block was gradually replaced by bone and histopathologic
features of the cement area were similar to that of natural bone.
Moreover, the coronal half of the implants, previously surrounded by
the calcium orthophosphate cement, was firmly attached by natural
bone [480]. In another study, the same researchers used fluorescent
labeling analysis and electron microanalysis to measure the extent of
new bone formation and elemental (Ca, P, Mg) distribution [481]. The
results indicated the presence of newly formed bone at ~ 1 month
after surgery and similar elemental distributions in the calcium
orthophosphate cement and natural bone areas at ~ 6 months after
surgery [202]. Besides, calcium orthophosphate cements were tried
as root canal fillers [59, 482, 483] and for pulp capping [484].
A hydraulic calcium orthophosphate cement was injected as
a bone filler for gaps around oral implants placed on the medial
femoral condyles of six goats and found excellent bone formation
around the graft material. Unfortunately, the degradation rate of the
cement appeared to be very slow and no resorption was observed
[485]. In another study, a cement was placed on artificially created
periodontal defects but no significant difference was found between
the cement and control. However, the cement acted as a scaffold for
bone formation and provided histocompatible healing of periodontal
tissues [486]. Still other investigators used a cement for direct pulp
capping [487, 488] and compared it to calcium hydroxide. Both
materials were found to be equally capable of producing a secondary
dentin at ~ 24 weeks [488]. Finally, injectable forms of calcium
orthophosphate cements can be used as an adjunctive supportive
agent for dental implants [489].
5.8.2
Craniofacial and Maxillofacial Applications
The use of self-setting calcium orthophosphate formulations for
craniofacial applications seems logical, as there is little or no stress
generated under these conditions. Moreover, the ability to mold the
material at placement is an enormous advantage from a cosmetics
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