## 4 Discussion  
The purpose of regenerative periodontal treatments is to restore physiological dental function by reconstructing periodontal tissues such as the alveolar bone, gingiva, periodontal ligament, and cementum. With tissue regeneration, destructive periodontal tissues can be rebuilt by using stem cells, growth factors, or extracellular matrix scaffolds. Until now, various types of stem cells have been used to regenerate periodontal tissues; today these include Mesenchymal Stem Cells (MSCs) [32]. In 2010, [PERSON] et al. isolated Adipose-Derived Stem Cells (ADSCs) from a mass of fatty tissue in the oral cavity called the Buccal Fat Pad. Under appropriate conditions, it has been shown that ADSCs Derived From the Buccal Fat Pad (BFPADSCs) differentiate into chondrocytes, osteoblasts, or fat cells [7]. This study used Human Buccal Fat Pad mesenchymal cells to regenerate periodontal tissues. Laser therapy is widely used to increase the speed of tissue regeneration. Studies have shown an increase in the proliferation rate of cells such as fibroblasts and osteoblasts. In mesenchymal cells, studies have shown that PBMT has a positive effect on mesenchymal stem cells obtained from bone marrow and adipose tissue [33; 34]. One of the crucial issues that should be considered in choosing the wavelength is the optical window, in which the effective permeability of light into the tissue is the maximum. The optical window is approximately in the range of 650 nm to 1200 nm. The amount of absorption and diffusion of light in the blue region of the spectrum is higher than in the red region because the main chromophores in tissue (hemoglobin and melanin) have the highest absorption and scattering of light at shorter wavelengths. In addition, water absorbs infrared light at wavelengths greater than 1100 nm. Therefore, the use of PBMT in patients and animals is in the range of red and near-infrared light (600-1100 nm). [35]. In our study, our wavelengths were 635 nm, 660 nm, 808 nm, and 980 nm, which are in the abovementioned range. Another parameter that should be considered in cell stimulation is energy density. According to the studies of [PERSON] and [PERSON], cell stimulation can be achieved at low doses, such as 0.001 J/cm\({}^{2}\), and even at higher doses, with 10 J/cm\({}^{2}\) being the maximum amount [36]. In this study, energy densities were 1, 1.5, 2.5, and 4 J/cm\({}^{2}\), which are in the abovementioned range. According to published studies, wavelengths in the range of 810 nm are one of the most used wavelengths for PBM treatment. The mechanism of their function is that the photons of these wavelengths are absorbed by the chromophores in cytochrome C oxidase and stimulate mitochondrial metabolism by increasing MMP and O2 absorption; therefore, they will increase the production of ATP [37]. In this study, the 808 nm wavelength was significantly higher on the first and third days than the other three wavelengths. In addition, the 808 nm wavelength was greater on the fifth day than other wavelengths at 1, 1.5, and 2.5 J/cm\({}^{2}\). In the study by [PERSON] et al., the mechanism of the effect of 810 and 980 nm wavelengths on fat stem cells was investigated. They wanted to test the hypothesis that the 980 nm chromophore is intercellular water that can create a microscopic temperature gradient during laser irradiation. To achieve this, 4 \({}^{\circ}\)C cold medium was added during laser \begin{table}
\begin{tabular}{c c c c c} \hline
**Energy Density** & **1 J/cm\({}^{2}\)** & **1.5 J/cm\({}^{2}\)** & **2.5 J/cm\({}^{2}\)** & **4 J/cm\({}^{2}\)** \\ \hline wavelength & & & & \\ \hline control & 101.11 & 101.11 & 101.11 & 101.11 \\ \hline
635 nm & 98.706 & 116.94 & 105.71 & 124.08 \\ \hline
660 nm & 114.48 & 118.43 & 112.64 & 113.84 \\ \hline
808 nm & 131.37 * & 145.55961 * & 145.84 * & 129.9 \\ \hline
980 nm * & 99.442 & 98.755 & 104.1 & 115.86 \\ \hline \end{tabular}
\end{table} 
Table 4: The viability of cells (%) on the fifth day (items marked with * are \(p<0.05\) in comparison with the control group).