Odontoblast response to cavity preparation with Er:YAG laser in rat molars: an immunohistochemical study.
This study aimed to examine the dynamics of odontoblast-lineage cells following cavity preparation with erbium:yttrium-aluminum-garnet (Er:YAG) laser in rat molars. Cavity preparation was made with Er:YAG laser in the mesial surface of the maxillary left first molar of 8-week-old Wistar rats. Contralateral first molar served as unirradiated control. Immediately, 6 and 12 h and 1, 2, 3, 5 and 7 days after the lasing (n = 5, each), specimens were collected and processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin as markers for odontoblast-lineage cells. Cell proliferation assay using bromodeoxyuridine (BrdU) labeling was also performed. Unirradiated teeth showed HSP-25- and nestin-immunoreactivity in odontoblasts. At 6-12 h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1-2 days, however, HSP-25- and nestin-immunoreactivities in the odontoblast layer showed a noticeable recovery, resulting in the rearrangement of odontoblast-like cells intensely immunoreactive to HSP-25 and nestin at 3-7 days. BrdU-positive cells showed a significant increase at 2 days (P < 0.05 vs. immediate previous time point; one-way analysis of variance and Scheffé post hoc test), peaked at 3 days and then decreased significantly (P < 0.05). It was concluded that under the present experimental condition in rat molars, cavity preparation with Er:YAG laser induced mild and reversible damage to odontoblasts. The reparative process was characterized by the rearrangement of HSP-25- and nestin-immunoreactive odontoblast-like cells, which took place subsequent to the odontoblastic layer disorganization with partial loss of these immunoreactivities.
Division of Cariology, Operative Dentistry and Endodontics, Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan, yoshimi@dent.niigata-u.ac.jp.
Yoshimi
Y
Shigetani
Hironobu
H
Suzuki
Hayato
H
Ohshima
Kunihiko
K
Yoshiba
Nagako
N
Yoshiba
Takashi
T
Okiji
D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007834:Lasers; D008963:Molar / Q000528:radiation effects*; D009804:Odontoblasts / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar
D055551:HSP27 Heat-Shock Proteins; C486114:Hspb1 protein, rat; D001973:Bromodeoxyuridine