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Pulpal effects of enamel ablation with a microsecond pulsed λ = 9.3‐µm CO 2 laser
Author(s) -
Staninec Michal,
Darling Cynthia L.,
Goodis Harold E.,
Pierre Daniel,
Cox Darren P.,
Fan Kenneth,
Larson Michael,
Parisi Renaldo,
Hsu Dennis,
Manesh Saman K.,
Ho Chi,
Hosseini Mehran,
Fried Daniel
Publication year - 2009
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20748
Subject(s) - enamel paint , ablation , laser , microsecond , dentin , fluence , molar , irradiation , pulse duration , materials science , dentistry , biomedical engineering , medicine , optics , physics , nuclear physics
Background and Objectives In vitro studies have shown that CO 2 lasers operating at the highly absorbed 9.3 and 9.6‐µm wavelengths with a pulse duration in the range of 10–20‐microsecond are well suited for the efficient ablation of enamel and dentin with minimal peripheral thermal damage. Even though these CO 2 lasers are highly promising, they have yet to receive FDA approval. Clinical studies are necessary to determine if excessive heat deposition in the tooth may have any detrimental pulpal effects, particularly at higher ablative fluencies. The purpose of this study was to evaluate the pulpal safety of laser irradiation of tooth occlusal surfaces under the conditions required for small conservative preparations confined to enamel. Study Design/Materials and Methods Test subjects requiring removal of third molar teeth were recruited and teeth scheduled for extraction were irradiated using a pulsed CO 2 laser at a wavelength of 9.3 µm operating at 25 or 50 Hz using a incident fluence of 20 J/cm 2 for a total of 3,000 laser pulses (36 J) for both rates with water cooling. Two control groups were used, one with no treatment and one with a small cut made with a conventional high‐speed hand‐piece. No anesthetic was used for any of the procedures and tooth vitality was evaluated prior to treatment by heat, cold and electrical testing. Short term effects were observed on teeth extracted within 72 hours after treatment and long term effects were observed on teeth extracted 90 days after treatment. The pulps of the teeth were fixed with formalin immediately after extraction and subjected to histological examination. Additionally, micro‐thermocouple measurements were used to estimate the potential temperature rise in the pulp chamber of extracted teeth employing the same irradiation conditions used in vivo. Results Pulpal thermocouple measurements showed the internal temperature rise in the tooth was within safe limits, 3.3±1.4°C without water cooling versus 1.7±1.6°C with water‐cooling, n = 25, P <0.05. None of the control or treatment groups showed any deleterious effects on pulpal tissues and none of the 29 test‐subjects felt pain or discomfort after the procedure. Only two test‐subjects felt discomfort from “cold sensitivity” during the procedure caused by the water‐spray. Conclusion It appears that this CO 2 laser can ablate enamel safely without harming the pulp under the rate of energy deposition employed in this study. Lasers Surg. Med. 41:256–263, 2009. © 2009 Wiley‐Liss, Inc.