Immunohistochemical study on pulpal response in rat molars after cavity preparation by Er:YAG laser.
While Er:YAG laser systems are in extensive use for caries removal and cavity preparation, the effects of such treatment on pulp tissue remain unclear. This study evaluates these systems using immunohistochemical methods and compares the results with information gained from treatment using conventional burs. Cervical cavities were prepared in the upper first molars of rats, using either an Er:YAG laser or a conventional tungsten-carbide bur. At intervals of 5 min, 6 h, 12 h, 1 d, 3 d and 7 d after cavity preparation, the teeth were processed for immunohistochemical analyses of tissue non-specific alkaline phosphatase, OX6-positive major histocompatibility complex class II antigen-expressing cells and PGP 9.5-immunoreactive nerve fibers. DNA fragmentation was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Tissue non-specific alkaline phosphatase was observed mainly in the subodontoblastic layer under the cavity lesion, from 5 min, in both groups. The immunoreactivity was more pronounced in the laser group, but by 7 d no significant differences were recognizable. At 12 h, TUNEL-positive cells were detected around the odontoblastic layer in both groups. From 3 d to 7 d, a limited number of positive cells were still visible in the group that underwent standard treatment. Clear similarities in the distribution patterns of OX6-immunopositive cells and PGP 9.5-immunoreactive nerve fibers were also noted. From 12 h to 1 d, OX6-positive cells accumulated along the pulp-dentin border, extending their processes into the dentinal tubules. Numerous bead-like PGP 9.5-immunoreactive nerve fibers were observed under the odontoblastic layer at 7 d. These results demonstrated that there was no appreciable difference in the manner in which pulp tissue responded to treatment with either Er:YAG laser or a conventional drill. This would seem to indicate the usefulness of the Er:YAG laser system in the removal of caries and cavity preparation.
Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, Japan.
Keita
K
Tanabe
Kunihiko
K
Yoshiba
Nagako
N
Yoshiba
Masaaki
M
Iwaku
Hidehiro
H
Ozawa
D000469:Alkaline Phosphatase / Q000032:analysis; D000538:Aluminum Silicates; D000818:Animals; D000938:Antigen-Presenting Cells / Q000473:pathology; D053938:DNA Fragmentation; D003737:Dental Cavity Preparation / Q000295:instrumentation / Q000379:methods*; D003782:Dental Pulp / Q000473:pathology*; D003804:Dentin / Q000473:pathology; D004871:Erbium; D019085:Fluorescent Antibody Technique, Direct; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D053685:Laser Therapy; D008297:Male; D008963:Molar; D009412:Nerve Fibers / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000032:analysis; D009804:Odontoblasts / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013223:Statistics as Topic; D013869:Thiolester Hydrolases / Q000032:analysis; D013997:Time Factors; D019237:Tooth Cervix / Q000601:surgery; D017973:Tungsten Compounds; D043222:Ubiquitin Thiolesterase; D015019:Yttrium
D000538:Aluminum Silicates; D000949:Histocompatibility Antigens Class II; D009419:Nerve Tissue Proteins; D017973:Tungsten Compounds; C002802:tungsten carbide; D015019:Yttrium; D004871:Erbium; D013869:Thiolester Hydrolases; D000469:Alkaline Phosphatase; D043222:Ubiquitin Thiolesterase