Effect of systemic parathyroid hormone (1-34) and a beta-tricalcium phosphate biomaterial on local bone formation in a critical-size rat calvarial defect model.
OBJECTIVE
The objective of this study was to evaluate local bone formation following systemic administration of parathyroid hormone (1-34) (PTH), a surgically implanted synthetic beta-tricalcium phosphate (beta-TCP) bone biomaterial serving as a matrix to support new bone formation.


METHODS
Critical-size, 8 mm, calvarial through-and-through osteotomy defects were surgically created in 100 adult male Sprague-Dawley rats. The animals were randomized into five groups of 20 animals each to receive one of the following treatments: PTH (15 microg PTH/kg/day; subcutaneously), PTH/beta-TCP, beta-TCP, or particulate human demineralized freeze-dried bone (DFDB), and sham-surgery controls. Ten animals/group were euthanized at 4 and 8 weeks post-surgery for radiographic and histometric analysis.


RESULTS
The histometric analysis showed that systemic PTH significantly enhanced local bone formation, bone fill averaging (+/-SE) 32.2+/-4.0% compared with PTH/beta-TCP (15.7+/-2.4%), beta-TCP (12.5+/-2.3%), DFDB (14.5+/-2.3%), and sham-surgery control (10.0+/-1.5%) at 4 weeks (p<0.014). Systemic PTH showed significantly enhanced bone formation (41.5+/-4.0%) compared with PTH/beta-TCP (22.4+/-3.0%), beta-TCP (21.3+/-4.4%), and with the sham-surgery control (23.8+/-4.2%) at 8 weeks (p<0.025). The DFDB group showed significantly increased bone formation from 4 (14.5+/-2.3%) to 8 weeks (32.0+/-3.2%) (p<0.006). The PTH/beta-TCP and beta-TCP groups both showed limited biomaterials resorption. The radiographic analysis was not diagnostic to distinguish local bone formation from the radiopaque beta-TCP biomaterial.


CONCLUSIONS
Systemic administration of PTH significantly stimulates local bone formation. Bone formation was significantly limited by the beta-TCP biomaterial.
US Army Advanced Education Program in Periodontics, US Army, Ft. Gordon, GA, USA. jonathan.yun@us.army.mil
Jonathan I
JI
Yun
Ulf Me
UM
Wikesjö
James L
JL
Borke
Frederick C
FC
Bisch
Jill E
JE
Lewis
Robert W
RW
Herold
Gary D
GD
Swiec
Joseph C
JC
Wood
James C
JC
McPherson
D000818:Animals; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001857:Bone Matrix / Q000637:transplantation; D001861:Bone Regeneration / Q000187:drug effects*; D002130:Calcium Phosphates / Q000494:pharmacology; D007267:Injections; D008297:Male; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012886:Skull / Q000601:surgery
D050071:Bone Density Conservation Agents; D002130:Calcium Phosphates; D010281:Parathyroid Hormone; C485817:beta-tricalcium phosphate