Effect of intermittent systemic administration of recombinant parathyroid hormone (1-34) on mandibular fracture healing in rats.
OBJECTIVE
To establish a rat mandibular fracture model and investigate the short- and long-term effects of recombinant parathyroid hormone (PTH 1-34) on mandibular fracture healing in rats.


METHODS
A controlled unilateral mandibular fracture was created surgically in 29 male Sprague-Dawley rats and then stabilized using an external fixation device. The rats were divided into 2 groups: 1 group received daily subcutaneous injections of 10 microg/kg of PTH(1-34) and 1 group served as the vehicle control. The rats were killed on postoperative days 7 and 21, and radiographic densitometry and histologic evaluation of new bone formation were performed.


RESULTS
A novel unilateral mandibular fracture model was established that has significant differences from previously published models, both in the location of the osteotomy site and in the rigid external stabilization device. The PTH(1-34) treated rats showed a statistically significant difference (P < .05) in callous formation compared with the control animals. Radiographic densitometry evaluation of the injury site revealed an increase in bone density, apparent at day 7 in the experimental group. Visual inspection of the histologic sections stained with Masson's trichrome blue showed an apparent increase in new bone formation at 21 days in the PTH-treated group compared with the control group.


CONCLUSIONS
Intermittent systemic administration of PTH(1-34) might enhance the healing of mandibular fractures in the early phase (7-day period). Long-term administration (21-day period) showed no statistically significant differences between the control and experimental group by radiographic densitometry.
Rowshan
Henry H
HH
Oral and Maxillofacial Surgery, Ft Irwin, CA, USA.
Parham
Mary A
MA
Baur
Dale A
DA
McEntee
RaeLynn D
RD
Cauley
Eugene
E
Carriere
Dane T
DT
Wood
Joseph C
JC
Demsar
William J
WJ
Pizarro
Jose M
JM
D000818:Animals; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D001861:Bone Regeneration / Q000187:drug effects; D005593:Fracture Fixation, Internal; D017102:Fracture Healing / Q000187:drug effects*; D006801:Humans; D008297:Male; D008337:Mandibular Fractures / Q000601:surgery*; D010281:Parathyroid Hormone / Q000008:administration & dosage*; D010446:Peptide Fragments / Q000008:administration & dosage*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage; D019379:Teriparatide / Q000008:administration & dosage / Q000031:analogs & derivatives*
D050071:Bone Density Conservation Agents; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D011994:Recombinant Proteins; D019379:Teriparatide; C035748:parathyroid hormone (1-34)amide