Biomaterial Database

Pulpal effects of enamel ablation with a microsecond pulsed lambda = 9.3-microm CO2 laser. 2009

Michal Staninec, and Cynthia L Darling, and Harold E Goodis, and Daniel Pierre, and Darren P Cox, and Kenneth Fan, and Michael Larson, and Renaldo Parisi, and Dennis Hsu, and Saman K Manesh, and Chi Ho, and Mehran Hosseini, and Daniel Fried

Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, 707 Parnassus Ave, San Francisco, California 94143-0758, USA.

OBJECTIVE In vitro studies have shown that CO2 lasers operating at the highly absorbed 9.3 and 9.6-microm 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 CO2 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. METHODS Test subjects requiring removal of third molar teeth were recruited and teeth scheduled for extraction were irradiated using a pulsed CO2 laser at a wavelength of 9.3 microm 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 degrees C without water cooling versus 1.7+/-1.6 degrees 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. CONCLUSIONS It appears that this CO2 laser can ablate enamel safely without harming the pulp under the rate of energy deposition employed in this study.

UI	MeSH Term	Description	Entries
D008963	Molar	The most posterior teeth on either side of the jaw, totaling eight in the deciduous dentition (2 on each side, upper and lower), and usually 12 in the permanent dentition (three on each side, upper and lower). They are grinding teeth, having large crowns and broad chewing surfaces. (Jablonski, Dictionary of Dentistry, 1992, p821)	Molars
D003743	Dental Enamel	A hard thin translucent layer of calcified substance which envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. Under the microscope, it is composed of thin rods (enamel prisms) held together by cementing substance, and surrounded by an enamel sheath. (From Jablonski, Dictionary of Dentistry, 1992, p286)	Enamel,Enamel Cuticle,Dental Enamels,Enamel, Dental,Enamels, Dental,Cuticle, Enamel,Cuticles, Enamel,Enamel Cuticles,Enamels
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D053685	Laser Therapy	The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.	Laser Knife,Laser Scalpel,Surgery, Laser,Vaporization, Laser,Laser Ablation,Laser Knives,Laser Photoablation of Tissue,Laser Surgery,Laser Tissue Ablation,Nonablative Laser Treatment,Pulsed Laser Tissue Ablation,Ablation, Laser,Ablation, Laser Tissue,Knife, Laser,Knifes, Laser,Knive, Laser,Knives, Laser,Laser Knifes,Laser Knive,Laser Scalpels,Laser Surgeries,Laser Therapies,Laser Treatment, Nonablative,Laser Treatments, Nonablative,Laser Vaporization,Nonablative Laser Treatments,Scalpel, Laser,Scalpels, Laser,Surgeries, Laser,Therapies, Laser,Therapy, Laser,Tissue Ablation, Laser
D054020	Lasers, Gas	Lasers in which a gas lasing medium is stimulated to emit light by an electric current or high-frequency oscillator.	Argon Ion Lasers,CO2 Lasers,Carbon Dioxide Lasers,Copper Vapor Lasers,Gas Lasers,Gold Vapor Lasers,Helium Lasers,Helium Neon Gas Lasers,Metal Vapor Lasers,Nitrogen Lasers,Xenon Ion Lasers,HeNe Lasers,Lasers, Argon Ion,Lasers, CO2,Lasers, Carbon Dioxide,Lasers, Copper Vapor,Lasers, Gold Vapor,Lasers, Helium,Lasers, Helium Neon Gas,Lasers, Metal Vapor,Lasers, Nitrogen,Lasers, Xenon Ion,Argon Ion Laser,CO2 Laser,Carbon Dioxide Laser,Copper Vapor Laser,Dioxide Laser, Carbon,Dioxide Lasers, Carbon,Gas Laser,Gold Vapor Laser,HeNe Laser,Helium Laser,Ion Laser, Argon,Ion Laser, Xenon,Ion Lasers, Argon,Ion Lasers, Xenon,Laser, Argon Ion,Laser, CO2,Laser, Carbon Dioxide,Laser, Copper Vapor,Laser, Gas,Laser, Gold Vapor,Laser, HeNe,Laser, Helium,Laser, Metal Vapor,Laser, Nitrogen,Laser, Xenon Ion,Lasers, HeNe,Metal Vapor Laser,Nitrogen Laser,Vapor Laser, Copper,Vapor Laser, Gold,Vapor Laser, Metal,Vapor Lasers, Copper,Vapor Lasers, Gold,Vapor Lasers, Metal,Xenon Ion Laser
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In