1. Action of laser on tissues Presented by- Dr. Md Nazrul Islam. Assistant Registrar, Orthopedic and traumatology Department, Shaheed Suhrawardy Hospital, Dhaka. “ Laser in Orthopedic Surgery ” (Part-2)

4. Electromagnetic Spectrum: Wavelength: It is the distance between repeating units of a propagating wave of a given frequency. Frequency: It is the number of occurrences of a repeating event per unit time.

5. Basic steps of laser action on biologic tissues:

6. Laser-tissue interactions

7. Basic effects of laser on tissues

8. Laser-tissue interactions

9. Mechanism of action of laser:

12. Phenomena of thermal effects of laser :

14. Video clip on cutting (Thermal) effect of laser:

15. Thermal effects of a laser beam. Laser osteotomy with the CO2-laser

16. Thermal effects of a laser beam.

18. Mechanical effects of laser :

21. Video clip on photoablative effect of laser :

22. The photoablative effect of laser :

23. Photoablative effect of Laser:

24. Application of photoablative effects

25. Application of photoablative effects

26. 4. The photodynamic effect Photodynamic therapy (PDT) is based on photoactive drugs that produce excited singlet-state oxygen molecules from local (ground-state) oxygen molecules under illumination with visible light.1 The singlet oxygen produces reactive oxygen species, primarily free radicals such as ·OH. These free radicals attack DNA and other vital biomolecules in the cell, leading to cell death.. Due to the limited tissue penetration of visible light, PDT has mostly been utilized for skin cancers. Applications : Cancer Psoriasis Macular degeneration

28. The photodynamic effect of laser:

29. 5. Photochemical and Photobiological effects of Laser:

32. To subside inflammation and Pain.

33. To subside inflammation and Pain.

34. To subside inflammation and Pain .

35. To subside inflammation and Pain .

36. Healing skin ulcer, wound Bedsore.

37. Hard and soft tissues (Bone/ Muscular /nerve tissue) regeneration / growth.

38. Laser photosynthesis of vitamin D .

39. Hard and soft tissues (Bone/ Muscular /nerve tissue) regeneration / growth.

40. Hard and soft tissues (Bone/ Muscular /nerve tissue) regeneration / growth.