No abstract

No abstract

This assignment applies to all translations of the Work as well as to preliminary display/posting of the abstract of the accepted article in electronic form before publication. If any changes in authorship (order, deletions, or additions) occur after the manuscript is submitted, agreement by all authors for such changes must be on file with the Publisher. An author's name may be removed only at his/her written request. (Note: Material prepared by employees of the US government in the course of their official duties cannot be copyrighted.

The purpose of the present study is to evaluate the effects of low-level laser therapy on the osseointegration process by comparing resonance frequency analysis measurements performed at implant placement and after 30 days and micro-computed tomography images in irradiated vs nonirradiated rabbits. Fourteen male New Zealand rabbits were randomly divided into two groups of seven animals each, one control group (nonirradiated animals) and one experimental group that received low-level laser therapy (Thera Lase®, aluminum-gallium-arsenide laser diode, 10 J per spot, two spots per session, seven sessions, 830 nm, 50 mW, CW, Ø 0.0028 cm). The mandibular left incisor was surgically extracted in all animals, and one osseointegrated implant was placed immediately afterward (3.25ø × 11.5 mm; NanoTite, BIOMET 3i). Resonance frequency analysis was performed with the Osstell® device at implant placement and at 30 days (immediately before euthanasia). Micro-computed tomography analyses were then conducted using a high-resolution scanner (SkyScan 1172 X-ray Micro-CT) to evaluate the amount of newly formed bone around the implants. Irradiated animals showed significantly higher implant stability quotients at 30 days (64.286 ± 1.596; 95 % confidence interval (CI) 60.808-67.764) than controls (56.357 ± 1.596; 95 %CI 52.879-59.835) (P = .000). The percentage of newly formed bone around the implants was also significantly higher in irradiated animals (75.523 ± 8.510; 95 %CI 61.893-89.155) than in controls (55.012 ± 19.840; 95 %CI 41.380-68.643) (P = .027). Laser therapy, based on the irradiation protocol used in this study, was able to provide greater implant stability and increase the volume of peri-implant newly formed bone, indicating that laser irradiation effected an improvement in the osseointegration process.

Objective: The purpose of this study was to demonstrate the effect of low-level laser therapy (LLLT) on the peri-implant bone healing process in the rabbit mandible. Background data: LLLT has been shown to accelerate tissue repair and osseointegration of implants placed into the rabbit tibia. However, the beneficial effects of LLLT have never been tested in the rabbit mandible, which would more closely mimic the human situation. Materials and methods: Twenty-four male New Zealand rabbits were randomly divided into four groups of six animals each. All animals had their left mandibular incisors extracted, followed by immediate insertion of a titanium dental implant in the fresh socket. Three groups received LLLT [aluminum-galliumarsenide (AlGaAs), k = 830nm, 50 mW, continuous wave (CW)] at three different energy densities per treatment session (E-5, 5 J/cm 2 ; E-10, 10 J/cm 2 ; and E-20, 20 J/cm 2 ). Irradiation was performed every 48 h for 13 days, totaling seven sessions. One group received sham treatment (controls). Histological sections were obtained from each of the 24 mandibles dissected, without first decalcifying the specimens, and were stained with hematoxylin and eosin and Picrosirius red for histomorphometric evaluation. Bone-to-implant contact (BIC), bone formation area, and collagen fiber area were assessed by light microscopy. Results: Significant differences were found between group E-20 and all other groups ( p < 0.05). Histomorphometric evaluation showed significantly higher BIC and significantly more collagen fibers in group E-20. Conclusions: Photobiostimulation with LLLT at an energy density of 20 J/cm 2 per session had a significant positive effect on new bone formation around dental implants inserted in the rabbit mandible.

Objective: The purpose of this study was to assess the systemic effects of low-level laser therapy (LLLT) on thyroid gland function and, consequently, calcium regulation -as measured by serum triiodothyronine (T3), thyroxine (T4), and free calcium levels -when administered after dental implant placement in a rabbit model. Background data: Protocols for the use of laser therapy in several clinical procedures are currently under investigation, as not all of the actions and systemic effects of laser irradiation have been clearly established. Materials and methods: Forty male adult New Zealand rabbits were distributed across five groups of eight animals each: two control groups (C-I and C-II) of unirradiated animals, and three experimental groups (E-5, E-10, and E-20), each exposed to a distinct dose of gallium-aluminum-arsenide (GaAlAs) laser [k = 830 nm, 50 mW, continuous wave (CW)] every 48 h for a total of seven sessions. The total dose per session was 5 J/cm 2 in E-5, 10 J/cm 2 in E-10, and 20 J/cm 2 in E-20. Animals in C-II and all experimental groups underwent surgical extraction of the mandibular left incisor followed by immediate placement of an osseointegrated implant (Nanotite Ò , Biomet 3i TM ) into the socket. Animals in group C-I served as an absolute control for T3, T4, and calcium measurements. The level of significance was set at 5% ( p £ 0.05). Results: ANOVA with Tukey's posthoc test revealed significant differences in T3 and calcium levels among experimental groups, as well as significant within-group differences in T3, T4, and calcium levels over time. Conclusions: Although not reaching abnormal values, LLLT applied to the mandible influenced thyroid function in this model.

No abstract

This study aimed to assess the systemic effect of LLLT on thyroid gland functioning and consequently on calcium regulation through Triiodothyronine (T 3) and Thyroxine (T 4) measurements in rabbits' serum. A total of thirty two New Zealand male rabbits were randomly distributed in four groups with eight animals each: control group C (nonirradiated animals), group EI (5 J/cm 2 per session), group EII (10 J/cm 2 per session) and group EIII (20 J/cm 2 per session). All animals underwent lower left incisor extraction followed by immediate insertion of an osseintegrated implant, providing an equality of initial clinical condition between the groups. The experimental groups were irradiated with aluminium gallium arsenide diode laser (GaAlAs, λ = 830 nm, 50 mW, CW), during 13 days at each 48 hours, totalizing 7 sessions. Laboratorial T 3 and T 4 measurements were done in four distinct moments (before surgical procedure, immediately after surgical procedure, after the first LLLT session and after the last LLLT session) in all animals. The results obtained showed statistically significant differences in Triiodothyronine values between the groups throughout the experiment. It was concluded that the LLLT, in the protocol of irradiation used in this study, promoted a significantly alteration on rabbits' serum hormonal levels.