Journal of Luminescence 102–103 (2003) 96–100 Spectroscopic study of ejected dental tissue after Er:YAG laser ablation L.C. Courrol a, *, D.M. Zezell b , R.E. Samad b , L. Gomes b a Laborat ! orio de Vidros e Data , c * ao, FATEC-SP, UNESP, Brazil b Centro de Lasers e Aplica , c * oes, IPEN/CNEN-SP, Cidade Universitaria, Travessa R400, Sao Paulo 05508-900, Brazil Abstract By means of IR spectroscopy, we determined the teeth ablation mechanism by an Er:YAG laser oscillating at 2.94 mm. Ejected dental material, ablated by the laser from human teeth, was deposited on an IR window and the absorption spectra were measured in the range 2500–20,000nm. Sound teeth were used, and the corresponding film spectrawerecomparedtospectraobtainedbytraditionalmethods.Thefilmsspectraobtaineddonotdifferappreciably from those obtained by the traditional method for sound teeth, indicating that the material ejected by an Er:YAG represents the tooth condition. The obtained results confirm that a spectroscopic analysis of a tooth treated with an Er:YAG laser can be done measuring the absorbance of a film composed of ejected material without the need to slice it. In addition, we could determinethatthelaserabsorptionoccursmainlybytheinterstitialwater,andthetemperatureelevationoftheejected material does not exceed 601C. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Er:YAG laser; Ablation; Spectroscopy; Temperature; Protein; Demineralization 1. Introduction Laser applications define one of the most importantareasofdentistrytoday.Usingthelaser itispossibletotreatthetoothinawidevarietyof new conditions that reduce pain, mechanical stress,noise,andpost-operativeproblems,without anesthesia in most of the cases. Lasers [1] can act ashighprecisiontoolsinnumerousapplicationsin softandharddentaltissues,asforexampleingum treatment, decay removal, sealant application, teeth whitening, drilling, etc [2]. In the last years, lasersbecameattractiveandaffordableforclinical use in dental tissue removal by ablative processes, due to recent developments in the diode laser and solid-state laser technology [3,4]. ThewavelengthoftheEr:YAGlaserradiationis 2.94 mm,whichcoincideswiththeabsorptionpeak of the stretching mode of the water molecule [5], thusbeingstronglyabsorbed.Thisintenseabsorp- tion within tooth micropores heats up the water instantaneously, changing its phase to vapor, increasing the pressure inside the micropore. This effect breaks the hydroxyapatite structure [6,7], leading to microexplosions that eject dental tissue away from the laser interacting volume. As a *Corresponding author. Centro de Lasers e Aplica , c * oes, IPEN/CNEN-SP, Cidade Universitaria, Travessa R400, Sao Paulo 05508-900, Brazil. Tel.: +55-11-38169314; fax: +55-11- 8169315. E-mail address: lcourrol@net.ipen.br (L.C. Courrol). 0022-2313/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0022-2313(02)00473-8