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ePaper created 2017-03-17, 12:41:55 | version 1.38.0
| research Periodontal therapy of deep localised pockets larger than 9 mm Adjunctive laser irradiation without antibiotics or open surgery Author: Dr Gottfried Gisler, MSc, Switzerland 1. Introduction The aim of this paper is to demonstrate that even “hopeless” teeth with very deep periodontal pockets of 10 mm and more pocket depth can be saved. Lasers as adjunctive therapy in periodontics have been described for a long time for the following reasons: Bactericidal effect of low-level laser application in photodynamic therapies1–4 and decrease of immune- inflammatory mediators5, stimulation of wound heal- ing with application of low-level lasers6–9, bactericidal effect10–12 or better wound healing for lasers in the near infrared like diode lasers13 or Nd:YAG lasers14,15, Fig. 1: Light absorption constants µA of biological materials.22 Fig. 1 06 laser 1 2017 calculus removing16,17, and bactericidal effect with la- sers in the middle infrared18–20 and stimulation of bone healing with Er:YAG lasers21. To achieve the above-mentioned effects of laser irradiation, the laser energy must be absorbed in the specific chromophores or absorbers of the tissues. The graph by Meister et al.22 in Fig. 1 gives a perfect overview about the different wavelengths and their chromophores applied in clinical situations. It can be seen that there is a high absorption in water for lasers in the mid-infrared like Er:YAG or Er,Cr:YSGG. A lower absorption was found for hydroxyapatite. The ab- sorption constant of 102 /cm in hydroxyapatite can lead to misunderstandings of ablation in hydroxy- apatite containing tissues like bone or dental hard tissues. If ablation in these tissues would occur by absorption in the secondary absorber for these wavelengths in the mid-infrared, the hydroxyapatite crystals would be strongly heated above the melting point and the generated heat would be transferred by conduction directly in the irradiated hard tissue. Ablation of dental hard tissues and bone occurs by absorption in water for the wavelengths in the mid- dle infrared. As can be seen in Fig. 1, the absorption curve shows a very high absorption in water at about 104 /cm. If water covers the irradiated surface during ablation, dental hard tissue and bone removal is achieved by explosive (water-mediated) ablation, socalled thermo-mechanical ablation.23 In this pro- cess, light is absorbed by water molecules, rapidly heating a small volume. The vaporisation of water