1397 Responses of Pulpal Cell and Nerve Fibers by Er:YAG and COsub>2 Laser Radiation
H. INOUE, T. EIDA, H. KAWANAMI, and T. IZUMI, Fukuoka Dental College, Japan

Objectives: Dental lasers are claimed to produce analgesia, but the mechanisms and extend of any effects are uncertain. The purpose of this study was to investigate the influence of Er:YAG and CO2 laser radiation on the dental pulp through the dental bard tissue in the rat. Methods: One hundred and twelve rat teeth were used in the study. The rats were anesthetized and were radiated with an Er:YAG and CO2 laser at the occlusal surface of a rat's molar. Er:YAG and CO2 laser radiation under such conditions as a spot diameter of 0.6mm(70mJ, 10pps, 10s)was performed on rat teeth, and responses of nerve fibers, odontoblasts, and pulp cells and pulp were investigated using electron and light microscopy at various time points after radiation(1,3,5days, 1w, 2ws, 3ws, 4ws, and 5ws). After various times of laser application, the animals were sacrificed,and the teeth were removed from the jaw. The pulpal reaction was evaluated histologically by light and electron microscopy on the paraffin sections stained with uranyle acetate and lead citrate. Results: The pulpal reactions following Er:YAG and CO2laser radiation were similar in totality.In the pulp tissue damaged by Er:YAG and CO2 laser radiation, degeneration of nerve fibers, nerve endings and Schwann cells was seen and reparation of these cells was slower than repair of other pulp cells. Pulp damage was histopathologically observed at the sphere of laser radiation, and stimulated dentin was recognized at the same portion. Conclusion: From the observed histological and ultrastructural changes in the pulpal nerves, Er:YAG and CO2 lasing could diminish sensations,including pain until repair.

Seq #152 - Pulpal Responses to Infection or Injury
11:00 AM-12:15 PM, Friday, 27 June 2003 Svenska Massan Exhibition Hall B

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