Low-level laser therapy on bone repair of rat tibiae exposed to ionizing radiation.
OBJECTIVE
The purpose of this study was to evaluate the effects of low-level laser therapy (LLLT) on the repair of rat tibiae exposed to ionizing radiation (IR).


BACKGROUND
IR causes structural changes that delay bone tissue repair. Properly dosed, LLLT improves the bone repair process.


METHODS
Seventy-two healthy Wistar rats were distributed into the following groups: Group I, sham control; Group II, LLLT; Group III, IR; and Group IV, IR and LLLT. Groups III and IV received a single dose (30 Gy) of gamma radiation and underwent surgery 28 days later. A noncritical sized bone defect (diameter 2.5 mm) was surgically created in all groups. Groups II and IV received three applications of postsurgical LLLT (GaAlAs, 808 nm, 100 mW, 0.028 cm(2), 3.57 W/cm(2), 20 sec, 2 J,≅71.4 J/cm(2)) on alternate days. Histomorphometry was assessed following digital image analysis.


RESULTS
The samples were evaluated on days 7, 14, and 21 after surgery; the IR protocol resulted in a significant reduction (p<0.018) in bone formation in Group III compared with Group I. Significant increases (p<0.006) in newly formed bone were noted in Group IV compared with Group III. No significant differences were observed between Group I and Group IV.


CONCLUSIONS
LLLT increased the newly formed bone area during the initial phase of the tibiae repair process in rats exposed to IR.
1 Division of Plastic Surgery, Department of Surgery, Universidade Federal de São Paulo , São Paulo, SP, Brazil .
Meire
M
Maman Fracher Abramoff
Max Domingues
MD
Pereira
Maria Teresa
MT
de Seixas Alves
Roberto Araújo
RA
Segreto
Arnaldo
A
Guilherme
Lydia Masako
LM
Ferreira
D000818:Animals; D001861:Bone Regeneration / Q000528:radiation effects*; D054023:Lasers, Semiconductor; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000628:therapy*; D011839:Radiation, Ionizing; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia / Q000528:radiation effects*