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ePaper created 2017-03-17, 12:41:55 | version 1.38.0
| research Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 6: Tooth 41, initial clinical situation (left) and radiological situation (right). Fig. 7: Tooth 44, initial clinical situation (left) and radiological situation (right). Fig. 8: Tooth 41, final clinical situation (left) and radiological situation (right), 15 months later. Fig. 9: Tooth 44, final clinical situation (left) and radiological situation (right), 15 months later. – frequency: 15–20 Hz – saphir tip: chisel (15 mm long) – water spray ~ 35–40 ml/min This setting with a fluence of about 6 J/cm2 allows the operator to work with minimal risk for the patient to overheat the irradiated tissues or even carbonisa- tion of dentine or bone in the subgingival area. The only thing to be considered is safely reaching the ab- lation threshold of the irradiated tissues like alveolar bone and root dentine at about a fluence of 2–4 J/cm2 respectively.36 movement and little rests of calculus can be re- moved. The irradiation time is only a few seconds. 2. Curettage: The inflamed soft tissue in the peri- odontal crater must be removed completely. The direction of the laser beam inside of the pocket is slightly directed towards the soft tissue and the movement of the chisel is from the margin of the gum to the pocket bottom. This irradiation lasts several minutes for each deep pocket. The curet- tage is finished when the chisel “reads” the osseous pocket bottom and can feel its anatomy. The pocket crater must be free of soft tissue. 3. Irradiation and stimulation of the bony pocket cra- ter by removing some micrometers of the superfi- cial surface: It’s a fresh-up of the alveolar pocket bottom. This irradiation lasts about one minute for each deep pocket. The expected effects in a closed periodontal treat- ment with lasers in the middle infrared in the first session are: – Removal of little rests of concrements on the sub- gingival root dentin.29 – Complete de-epithelization of the inner pocket up to the margin of the gum. – Removing of the inflamed pocket soft tissue. – Decontamination of the whole pocket including root surface, osseous and soft tissue parts with energy densities far below 10 J/cm2.19, 20 – Stimulation of the osseous pocket crater for bone regeneration.21 The whole irradiation time of a deep pocket is be- tween five to eight minutes. To avoid any carbonisa- tion in hard tissues (Fig. 2), such closed curettage by lasers with wavelengths in the mid-infrared need time. It is therefore totally different from an open cur with high laser settings, where the water spray pre- vents absorption of the energy in hydroxyapatite. There is an easy home experiment to demonstrate the effect of laser irradiation on dental hard tissues without water. One takes a freshly extracted wisdom tooth between one’s fingers and irradiates dentine at these wavelengths without water with laser settings as illustrated in Fig. 2. If the fluence is about 60 J/cm2, then after some pulses of irradiation the tissue water of dentine is totally consumed and absorption in hydoxy- apatite starts immediately. After some seconds one is no more able to hold the irradiated wisdom tooth be- tween one’s fingers. It becomes too hot! The clinical effect is carbonisation of the dentine. In enamel there is less ablation but high heat generation (Fig. 2). Application technique 1. Irradiation of the subgingival root surface: The laser beam must be parallel29,30 to the root surface and the movement is from crown to pocket bottom. The pocket should be slightly enlarged by this Directly after Er:YAG irradiation of the pocket, transmucosal photodynamic therapy (tPDT) with a soft laser (Med-701, LASOTRONIC®) is applied. The tPDT is done with a buffered 1 % methylene blue 10 laser 1 2017