فصلنامه لیزر در پزشکی
سال هشتم شماره 1 (پیاپی 39، بهار 1390)

Fluorescence molecular imaging (FMI) in reflectance mode is a powerful method for providing valuable information about pathologic processes.Tumor growth is a common pathologic process which can be traditionally obtained by caliper measurement. The caliper measurement has several major disadvantages. However FMI method can be used as a non-invasibly method. The goal of this project is validating FMI of tumor growth by comparing it to traditional tumor volume measurement method such as caliper measurement. Here we used an animal tumor model to evaluate the extent on correlation between noninvasively measured fluorescence and traditional methods. BALB/c mice received subcutaneous injection of WEHI-164 cells. The tumor size was measured. Fluorescein was directly injected in center of the tumor. Serial measurements of fluorescence intensities were performed with FMI. After imaging, the mice were sacrificed and tumor was removed for weighting. The results showed that Spearman correlation coefficient between tumor volume and the maximum height of fluorescent intensity in the first, the second and the third group are 0.019, 0.5 and 0.09 respectively. The ROC analysis showed that the cutoff point of tumor volume and the weight are 93 mm3 and 0.12g respectively. The measurement of tumor growth in the BALB/c mice by imaging fluorescence correlates well with the traditional method of determining the tumor volume and with the increase in tumor weight that results from tumor growth. Given the great advantages of measuring fluorescence intensity, we conclude that FMI imaging is a the reliable and superior method for measuring experimental tumor growth in the small animals.

The application of laser in dentistry has gained special attention in caries removal, cavity preparation and surface modification to obtain best adhesion of restorative materials to dental tissue. The aim of this study was to compare the microleakage of composite restoration in occlusal and cervical parts of cavities prepared by Er:YAG laser and diamond bur. 12 human caries free third molars were selected for this study. Then, the teeth were randomly divided in 2 groups of 6 in each. The class V cavities were prepared on both buccal and lingual side of each teeth by Er:YAG or diamond bur. After etching and bonding procedure, the cavities were restored by composite resin incrementally and light cured for 40 sec. All tooth surfaces were coated with two layers of nail varnish leaving 1mm wide border around restoration margins. Then, the samples were immersed in 2% methylene blue solution. After 24 hours, they were washed and dried. The samples were bisected longitudinally into two equal buccal and lingual halves. Then, samples were assessed by using a light microscope. The extent of dye penetration in occlusal and cervical part was analyzed by Kruskal-Wallis. There was no significant difference in 2 groups. Regardless of the method of cavity preparation (Er:YAG laser or diamond bur) the microleakage of class V cavities in cervical part was significantly more than those in occlusal part.

The main objective of periodontal therapy is to eliminate bacterial biofilm from root surface but the anatomical complexity of the tooth roots and furcation areas make the accessibility difficult. Because that complementary treatment recommended for removal of the calculus and microbial deposits, one of these treatment is PDT or photodynamic therapy.PDT is a non-invasive treatment process that effective for treatment of periodontal disease and it's side effects and development of the resistance to PDT is less than antibiotics. The aim of this study was to review the relevant articles, concerning the application of PDT in treatment periodontal disease.

PubMed, GoogleScholar and ScienceDirect were searched electronically.

Results included 16 full text article. There is a controversy in the article about effect of PDT on the pocket depth and clinical attachment loss, some show the effectiveness of it but another dont show any differences between PDT and SRP. Laser showed be more effective than SRP for reduction of full mouth bleeding score.

It seems that PDT is more effective for adjunctive treatment not as a single treatment and multiple dose application is better than single dose.

Crosslinking and photodegradation mechanisms are induced by exposure to excimer laser irradiation which depends mainly on the irradiation dose. Tensile test was performed associated with the FTIR spectroscopy to investigate the changes after ArF laser irradiation on the tissue.

Samples from sheep renal capsule were irradiated by ArF excimer laser at 193nm. Young’s modulus is determined, in order to estimate the effect of irradiation in tensile test. The FTIR spectroscopy is used to study the variation of chemical and molecular structures.

Reduction of young’s modulus during 10 second exposure leads to the partial peptide bond scissions and stiffness decreasing. Aromatic acids absorption predominated between 10 to 30 sec exposure and tissue’s stiffness reaches its peak at 30 sec. Increasing the irradiation dose, the process of peptide bond scissions makes the stiffness drop and a shift of amide II frequency takes place to the lower frequency.

The aim of this study is to evaluate the effects of low intensity ultrasound (LIUS) on proliferation and growth indexes of rat Bone-Marrow mesenchymal stem cells (MSCs) in vitro.

Low intensity ultrasound was irradiated by Ip/IAve= 355 mW.cm-2 and 3 MHz frequency in continues mode. Bone marrow cells prepared from rat's tibia and femur central canal were cultured in medium complemented with FBS. Passage three confluent cells were irradiated by LIUS and during 7 days culture period proliferation and growth indexes of cells were evaluated by calculation of Population Doubling Number (PDN) and daily examination of the cell growth for drawing growth curve. Each experiment was performed three times for ten sample and the mean values were statistically compared by SPSS (16.0) software. In this study, passaged-3 cells were evaluated in terms of their bone and adipocyte differentiation potential.

According to growth curve, the cells affected by ultrasound, have short lag phase and their log phase was sharper and shorter than control group (without ultrasound treatment). In US group more population doubling number occurred (p<0.004); PD in US group was 17.3924±5.79 versus control group 14.087±4.69 (p<0.005). Passageed-3 cells were readily differentiated among bone and adipocyte lineages confirming their mesenchymal stem cell nature.

Taken together, we investigated that LIUS could significantly improve the proliferation and viability potential of rat MSCs in vitro.