Lasers in Medicine
Year:2012 | Volume:8 | Issue:4 (42)|Papers Count:6

Background: Intrabony lesions caused by periodontal disease are of particular importance in terms of treatment. Such lesions have been treated with different methods including the use of autogenous bone harvested or allogeneic grafts, guided tissue regeneration (GTR) and enamel matrix proteins use (EMP) or a combination of these methods. Recently, the use of low power laser or Low-level lasertherapy (LLLT) as one of the new methods to improve bone repair has been of great interest. The purpose of this study was to compare the use of autogenous bone alone and in combination with Low-level laser therapy (LLLT) in the treatment of two and three wall periodontal intrabony defects in vivo.Material and Methods: A number of 14 patients with moderate to severe chronic periodontitis were with bilateral intrabony defect (probing pocket depth of at least 5 mm and intrabony component of at least 3 mm) were included. In a split mouth study, 14 defects were treated in one side by OFD and autogenous bone while in the contralateral side Low-level laser therapy was done as an adjunct treatment to the OFD and autogenous bone grafting. A GaAlAs diode laser (830 nm) (continuous wave 40 Mw and fluence 4 J/cm2 with total energy density of 16 J/cm2) was used. Laser therapy was repeated at days 3, 5 and 7 with the same parameters. Re-entry surgeries were done after 3 months. Clinical probing pocket depth, clinical attachment level, gingival margin level, alveolar crest level and the deepest part of the defect all were recorded relative to an acrylic stent at baseline and after 3 months. intrabony defect depth was also recorded at baseline and after 3 months.Results: Application of a low level laser with the parameters listed reduced probing depth (3.78 ± 0.72 mm vs. 2.39 ± 1.02 mm), improved the clinical attachment level (3.42 ± 0.93 mm vs. 2.25 ± 1.12 mm), reduced the distance between deepest part of the defect to stent (3.21 ± 1.03 mm vs. 1.44 ± 0.20 mm) and also reduced defect depth (1.33 ± 0.18mm versus 2.50 ± 0.91 mm ) significantly when compared to control group, while it had no significant effect on gingival margin level and alveolar crest level.Conclusion: The results of this study suggest the use of low level laser therapy in combination with autogenous bone can improve the periodontal treatment outcome in terms of probing depth reduction, clinical attachment level improvement and reduction of the defect depth.

Background: Laser Interstitial Thermo Therapy (LITT) is a minimally invasive surgical method to treat tumors in liver. Modeling laser effects on tissue in LITT has many advantages over other heat monitoring methods such as studying light and heat transfer in tissue, changing the effective parameters of the laser and lower cost. Among different numerical methods, Dual Reciprocity Boundary Element Method (DRBEM) is the newest method used by researchers to solve problems of heat transfer in tissue.Material and Methods: In this study the temperature increase in liver tissue is analyzed with DRBEM. Monte Carlo method with variable step size and implicit capture technique is used for light transport in tissue. The result of the DRBEM is also compared with Finite Element Method (FEM) results.Results: The results showed that both methods converge to similar results and the differences in temperatures are less than 1oC. Due to one dimension decrease of the problem in DRBEM, the solving time increases comparing with other numerical methods like FEM.Conclusion: DRBEM is an accurate and fast method to study heat transfer in biological tissue in laser-tissue interaction.

Background: In this article, we consider tooth as two-layer model by including the enamel and dentin. We solve heat conduction equation in them and obtain its analytical solution and study temperature distribution function, when Er: YAG laser incident on them.Material and Methods: By concerning heat constants of the enamel and dentin, we plot temperature distribution function and discuss them.Results: By drawing the diagram in different cases, we find out when a beam of laser irradiates on a tooth as two-layer, the temperature approaches to zero in the depth of dentin very fast, but the maximum variation of the temperature is 34 degrees of Celsius.Conclusion: This variation of temperature is such that it cannot disturb and carbonized enamel and dentin. So, Er: YAG pulsed laser irradiant is confidence and it will not lead to disturbance of enamel and dentin.

Background: This investigation has explored the detectivity of Surface Enhanced Raman Scattering (SERS) of Troponin I enzyme (cTnI) for diagnosing heart attack or myocardial anfractuous.Material and Methods: In this article, we designed a photo detector to diagnose the cTnI by recording it's SERS spectrum. To achieve this goal, AlxGa1-xAs/GaAs quantum well photo detector was used. By optimizing the percentage of aluminum in barrier material and appointing a precise well width, the behavior of cTnI has been simulated through its SERS spectrum. Results: By simulating and optimizing of quantum well photo detector width, the complete optical absorption and detectivity for cTnI SERS spectrum has been obtained.Conclusion: A quantum well in the near infrared photo detector is a suitable device for diagnosing diseases by transforming optical signals into electrical signals. The optimum and proper design of photo detector obtain improved detectivity and precise detectivity process.