Effects of increased low-level diode laser irradiation time on extraction socket healing in rats.
In our previous studies, we confirmed that low-level laser therapy (LLLT) with a 980-nm gallium-aluminum-arsenide diode laser was beneficial for the healing of the alveolar bone in rats with systemic disease. However, many factors can affect the biostimulatory effects of LLLT. Thus, we attempted to investigate the effects of irradiation time on the healing of extraction sockets by evaluating the expressions of genes and proteins related to bone healing. The left and right first maxillary molars of 24 rats were extracted. Rats were randomly divided into four groups in which extraction sockets were irradiated for 0, 1, 2, or 5 min each day for 3 or 7 days. Specimens containing the sockets were examined using quantitative real-time reverse transcription polymerase chain reaction and western blotting. LLLT increased the expressions of all tested genes, Runx2, collagen type 1, osteocalcin, platelet-derived growth factor-B, and vascular endothelial growth factor, in a time-dependent manner. The highest levels of gene expressions were in the 5-min group after 7 days. Five minutes of irradiation caused prominent increases of the expression of all tested proteins after both 3 and 7 days. The expression level of each protein in group 4 was higher by almost twofold compared with group 1 after 7 days. Laser irradiation for 5 min caused the highest expressions of genes and proteins related to bone healing. In conclusion, LLLT had positive effects on the early stages of bone healing of extraction sockets in rats, which were irradiation time-dependent.
Department of Periodontology, School of Dentistry, Kyung Hee University, Seoul, South Korea.
Joon Bong
JB
Park
Su-Jin
SJ
Ahn
Yoon-Goo
YG
Kang
Eun-Cheol
EC
Kim
Jung Sun
JS
Heo
Kyung Lhi
KL
Kang
D000818:Animals; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D054023:Lasers, Semiconductor; D028022:Low-Level Light Therapy; D008297:Male; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014081:Tooth Extraction; D020390:Tooth Socket / Q000473:pathology* / Q000528:radiation effects*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D014945:Wound Healing / Q000235:genetics / Q000528:radiation effects*
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D015675:Osteocalcin