Low-level laser therapy improves bone formation: stereology findings for osteoporosis in rat model

© 2015, Springer-Verlag London.Low-level laser therapy (LLLT) benefits bone metabolism, but its use needs to be standardized. We evaluated the effects of LLLT on bone defects in calvaria of ovariectomized rats. Stereology was used to calculate tissue repair volume (Vtr), density of trabecular bone volume (Vvt), total volume of newly formed trabecular bone (Vtot), and the area occupied by collagen fibers (AC). Fifty-four Wistar rats were submitted to bilateral ovariectomy, and bone defects were created in calvaria after 150 days. The animals were divided into nine groups (n = 6), and 24 h after defects, the treatment started with a 780-nm low-intensity GaAlAs laser: G1, G2, and G3 received 3 sessions of 0, 20, and 30 J/cm2 respectively; G4, G5, and G6 received 6 sessions of 0, 20, and 30 J/cm2, respectively; and G7, G8, and G9 received 12 sessions of 0, 20, and 30 J/cm2, respectively. A normal distribution was found for all of the data. The test used to verify the normality was the Kolmogorov-Smirnov (KS, p > 0.05). The one-way ANOVA followed by Tukey’s post hoc test was used for data processing. A difference of p tr, Vvt, Vtot, and (AC). Results were significant for (Vvt) and (Vtot) between G3 and G1. There were no significant results between G5 and G4 as well as between G8 and G7. Groups G6 and G4 results showed statistical difference for Vtr, Vvt, Vtot, and (AC). Groups G9 and G7 showed significance for Vtr, Vvt, Vtot, and (AC). In conclusion, there was new bone formation in the groups that received 20 and 30 J/cm2 when compared to control groups, but over time, the dose of 30 J/cm2 showed better stereological parameters when compared to 20 J/cm2

Low-level laser therapy improves bone formation: stereology findings for osteoporosis in rat model

© 2015, Springer-Verlag London.Low-level laser therapy (LLLT) benefits bone metabolism, but its use needs to be standardized. We evaluated the effects of LLLT on bone defects in calvaria of ovariectomized rats. Stereology was used to calculate tissue repair volume (Vtr), density of trabecular bone volume (Vvt), total volume of newly formed trabecular bone (Vtot), and the area occupied by collagen fibers (AC). Fifty-four Wistar rats were submitted to bilateral ovariectomy, and bone defects were created in calvaria after 150 days. The animals were divided into nine groups (n = 6), and 24 h after defects, the treatment started with a 780-nm low-intensity GaAlAs laser: G1, G2, and G3 received 3 sessions of 0, 20, and 30 J/cm2 respectively; G4, G5, and G6 received 6 sessions of 0, 20, and 30 J/cm2, respectively; and G7, G8, and G9 received 12 sessions of 0, 20, and 30 J/cm2, respectively. A normal distribution was found for all of the data. The test used to verify the normality was the Kolmogorov-Smirnov (KS, p > 0.05). The one-way ANOVA followed by Tukey’s post hoc test was used for data processing. A difference of p tr, Vvt, Vtot, and (AC). Results were significant for (Vvt) and (Vtot) between G3 and G1. There were no significant results between G5 and G4 as well as between G8 and G7. Groups G6 and G4 results showed statistical difference for Vtr, Vvt, Vtot, and (AC). Groups G9 and G7 showed significance for Vtr, Vvt, Vtot, and (AC). In conclusion, there was new bone formation in the groups that received 20 and 30 J/cm2 when compared to control groups, but over time, the dose of 30 J/cm2 showed better stereological parameters when compared to 20 J/cm2

Effect of gender, facial dimensions, body mass index and type of functional occlusion on bite force

OBJECTIVE: Some factors such as gender, age, craniofacial morphology, body structure, occlusal contact patterns may affect the maximum bite force. Thus, the purposes of this study were to determine the mean maximum bite force in individuals with normal occlusion, and to examine the effect of gender, facial dimensions, body mass index (BMI), type of functional occlusion (canine guidance and group function occlusion) and balancing side interferences on it. MATERIAL AND METHODS: Thirty-four individuals aged 19-20 years-old were selected for this study. Maximum bite force was measured with strain-gauge transducers at first molar region. Facial dimensions were defined by standardized frontal photographs as follows: anterior total facial height (ATFH), bizygomathic facial width (BFW) and intergonial width (IGW). BMI was calculated using the equation weight/height². The type of functional occlusion and the balancing side interferences of the subjects were identified by clinical examination. RESULTS: Bite force was found to be significantly higher in men than women (p<0.05). While there was a negative correlation between the bite force and ATFH/BFW, ATFH/IGW ratios in men (p<0.05), women did not show any statistically significant correlation (p>0.05). BMI and bite force correlation was not statistically significant (p>0.05). The average bite force did not differ in subjects with canine guidance or group function occlusion and in the presence of balancing side interferences (p>0.05). CONCLUSIONS: Data suggest that bite force is affected by gender. However, BMI, type of functional occlusion and the presence of balancing side interferences did not exert a meaningful influence on bite force. In addition, transverse facial dimensions showed correlation with bite force in only men