Division of Cariology, Operative Dentistry and Endodontics, Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, Nigata, Japan.
J Endod. 2011 Aug;37(8):1086-91. doi: 10.1016/j.joen.2011.05.020.
This study aimed to clarify pulpal responses to gallium-aluminum-arsenide (GaAlAs) laser irradiation.
Maxillary first molars of 8-week-old rats were irradiated at an output power of 0.5 or 1.5 W for 180 seconds, and the samples were collected at intervals of 0 to 14 days. The demineralized paraffin sections were processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin in addition to cell proliferation assay using bromodeoxyuridine (BrdU) labeling and apoptosis assay using deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (TUNEL).
Intense HSP-25 and nestin immunoreactivities in the odontoblast layer were weakened immediately after 0.5-W irradiation and recovered on day 1, resulting in slight tertiary dentin formation by day 14. On the contrary, 1.5-W irradiation immediately induced the loss of HSP-25 and nestin-immunoreactivities in the odontoblast layer. On day 1, numerous TUNEL-positive cells appeared in a degenerative zone that was surrounded by intense HSP-25 immunoreactivity. BrdU-positive cells occurred within the intensely HSP-25-immunopositive areas during days 2 through 5, whereas TUNEL-positive cells gradually decreased in number by day 5. HSP-25- and nestin-positive odontoblast-like cells were arranged along the pulp-dentin border by day 7, resulting in remarkable tertiary dentin formation on day 14.
The output energy determined pulpal healing patterns after GaAlAs laser irradiation; the higher energy induced the apoptosis in the affected dental pulp including odontoblasts followed by active cell proliferation in the intense HSP-25-immunoreactive areas surrounding the degenerative tissue, resulting in abundant tertiary dentin formation. Thus, the optimal GaAlAs laser irradiation elicited intentional tertiary dentin formation in the dental pulp.
本研究旨在阐明镓铝砷（GaAlAs）激光照射对牙髓的反应。
用 0.5 或 1.5 W 的输出功率照射 8 周龄大鼠的上颌第一磨牙 180 秒，每隔 0 到 14 天收集样本。对脱矿石蜡切片进行免疫组织化学染色，以检测热休克蛋白（HSP）-25 和巢蛋白，并用溴脱氧尿苷（BrdU）标记进行细胞增殖检测，用脱氧核苷酸转移酶脱氧尿苷三磷酸缺口末端标记（TUNEL）进行细胞凋亡检测。
0.5 W 照射后即刻，成牙本质细胞层中 HSP-25 和巢蛋白免疫反应性增强，第 1 天恢复，第 14 天形成轻微的第三期牙本质。相反，1.5 W 照射即刻导致成牙本质细胞层中 HSP-25 和巢蛋白免疫反应性丧失。第 1 天，在强烈的 HSP-25 免疫反应性区域周围出现大量 TUNEL 阳性细胞。第 2 天至第 5 天，BrdU 阳性细胞出现在强烈的 HSP-25 免疫阳性区域内，而 TUNEL 阳性细胞数量逐渐减少，第 5 天减少。第 7 天，HSP-25 和巢蛋白阳性的成牙本质细胞样细胞沿牙髓牙本质交界排列，第 14 天形成明显的第三期牙本质。
输出能量决定了 GaAlAs 激光照射后牙髓的愈合模式；较高的能量诱导受影响的牙髓包括成牙本质细胞凋亡，随后在强烈的 HSP-25 免疫反应性区域周围的退行性组织中出现活跃的细胞增殖，导致大量第三期牙本质形成。因此，最佳的 GaAlAs 激光照射可在牙髓中诱发有意的第三期牙本质形成。
