Comparative evaluation of various low-level laser therapies on bone healing following tooth extraction: An experimental animal study.

PURPOSE: The aim of this study was to evaluate the effects of helium-neon and gallium-aluminum-arsenide lasers with various doses on bone healing following tooth extraction. MATERIALS AND METHODS: Maxillary right incisor teeth of 30 female albino Wistar rats were extracted. Five groups were established: four groups treated with helium-neon or gallium-aluminum-arsenide lasers and a control group. Both laser groups' rats received energy doses of 6 J/cm2 and 10 J/cm2 for 7 days. At the end of 30 days, all subjects were sacrificed for histological and morphological evaluations. RESULTS: Laser groups showed faster bone healing and gallium-aluminum-arsenide lasers increased vascular immunoreactivity. The most widespread organized bone formation in the extraction socket was observed in the gallium-aluminum-arsenide laser group with the energy dose of 10 J/cm2 (p < 0.05). CONCLUSION: This study demonstrated that low-level laser therapies were effective on alveolar bone healing and that an energy dose of 10 J/cm2 did not have an inhibition effect on bone regeneration.

Effects of Low-Level Laser Therapy With a Herbal Extract on Alveolar Bone Healing.

PURPOSE: This study investigated the effect of a gallium-aluminum-arsenide (GaAlAs) diode laser used in low-level laser therapy (LLLT) with the application of Mecsina Hemostopper on mandibular alveolar bone healing. MATERIALS AND METHODS: Standard semispherical bone defects were created in left mandibular diastema sites of 32 female Long-Evans rats. Experimental animals were allocated to 1 of 4 groups: control group (no treatment), laser group (GaAlAs LLLT), Mecsina group, and laser-Mecsina combination group. Liquid Mecsina 0.01 mL was applied to the bone defects. Laser treatment was performed for 7 days after surgery at an energy dose of 10 J/cm2. All animals were sacrificed to observe hard tissue healing histologically, immunohistochemically, and radiologically at 30 days after surgery. RESULTS: Histologic assessment showed significantly more calcified tissue areas and significantly more osteoblast cells in the laser and laser-Mecsina groups than in the other groups (P < .01). Qualitative morphologic assessment showed that more bone tissue was present in the laser-Mecsina group than in the other groups. CONCLUSION: This study showed that LLLT, Mecsina application, and combined treatments were effective in healing alveolar bone among all tested treatment modalities.

Low-level laser therapy and invisible removal aligners.

It seems that Low Level Laser Therapy (LLLT) stimulates orthodontic tooth movements, increasing the alveolar bone turnover. The aim of this study is to evaluate how LLLT can influence the orthodontic treatment with invisible removal aligner. A sample of 21 subjects was divided into two groups, a laser group (10 patients) and a control group (11 patients). All subjects were instructed to wear each aligner 12 hours a day for 2 weeks. Laser external bio-stimulation was given in the laser group every second week. The laser group successfully finished the treatment, while at 3rd – 5th aligner the control group did not finish the treatment. Laser treatment seemed to be better than treatment without laser. LLLT combined with aligners is able to favour, in 12 hours, the same tooth movement obtained by wearing the aligner 22 hours a day, according to the traditional protocol. This aspect could be useful for those patients who prefer not to use the aligners during the day. LLLT makes invisible removal aligner treatment more comfortable also because during the day the patients have to wear the aligners less hours than the treatment without laser.

Effect of low-level laser therapy on orthodontic tooth movement into bone-grafted alveolar defects.

INTRODUCTION: The objective of this study was to investigate the effect of low-level laser therapy (LLLT) on the rate of orthodontic tooth movement (OTM) into bone-grafted alveolar defects based on different healing states. METHODS: Ten male beagles were randomly allocated to 3 groups: group C, OTM alone as a control; group G, OTM into the grafted defects; group GL, OTM into the grafted defects with LLLT. The maxillary second premolars were protracted into the defects for 6 weeks, immediately (G-0 and GL-0) and at 2 weeks (G-2 and GL-2) after surgery. The defects were irradiated with a diode laser (dose, 4.5 J/cm(2)) every other day for 2 weeks. The rates of OTM and alveolar bone apposition, and maturational states of the defects were analyzed by histomorphometry, microcomputed tomography, and histology. RESULTS: The total amounts of OTM and new bone apposition rates were decreased by LLLT, with increased bone mineral density and trabecular maturation in the defects. Group GL-2 had the slowest movement with root resorption in relation to less woven bone in the hypermatured defect. CONCLUSIONS: LLLT significantly decreased the rate of OTM into the bone-grafted surgical defects by accelerating defect healing and maturation, particularly when the start of postoperative OTM was delayed.

The Radiological and Stereological Analysis of the Effect of Low-Level Laser Therapy on the Mandibular Midline Distraction Osteogenesis.

OBJECTIVE: The aim of this study was to evaluate the effect of low level laser therapy (LLLT) on bone mineral density by using high-resolution computerized tomography (HR-CT) and stereology in patients subjected to mandibular midline distraction. METHODS: Nine patients between the ages of 13 and 16 years with mandibular transverse deficiency (>5 mm) were evaluated. Mandibular midline distraction osteogenesis was performed for all the patients. The patients were divided into 2 groups: the control group (n = 4) and the laser group (n = 5). GaAlAs, 830 nm wavelength, power of 40 mW, energy of 8.4 J/cm2 dose per spot, was directly applied from 2 points on the mandibular midline. The laser was applied in 8 treatment sessions at 48-hour intervals. Bone mineral density and volume of the newly formed bone were analyzed using HR-CT and stereological methods. RESULTS: A higher bone mineral density rate was found in the laser group (P < 0.05). A higher newly formed immature bone rate was found in the control group (P < 0.001). These findings suggest that more mature bone may also have a greater mineral organization than that of immature newly formed bone, which is shown by HR-CT and stereological results. CONCLUSIONS: The retention period can be shortened and mineralization may be increased by using LLLT in mandibular distraction osteogenesis.

Micro-computed tomography and histomorphometric analysis of human alveolar bone repair induced by laser phototherapy: a pilot study.

Immediate dental implant placement in the molar region is critical, because of the high amount of bone loss and the discrepancy between alveolar crest thickness and the implant platform. Laser phototherapy (LPT) improves bone repair. The aim of this study was to evaluate the human alveolar bone repair 40 days after molar extraction in patients submitted to LPT. Twenty patients were selected for this randomized controlled clinical trial; 10 underwent LPT (laser group) with a GaAlAs diode laser (808 nm, 100 mW, 0.04 cm(2), 75 J/cm(2), 30s per point, 3 J per point, at five points). The control group patients (n=10) were not irradiated. Forty days later, the tissue formed inside the sockets was analyzed by micro-computed tomography and histomorphometry. Data from the two groups were compared with Student's t-test and Pearson's correlation test. The relative bone volume was significantly higher in the laser group (P<0.0001). The control group showed negative correlations (P<0.01) between number and thickness, and between number and separation of trabeculae, and a positive correlation between thickness and separation of trabeculae. The laser group showed a significant negative correlation between the number and thickness of trabeculae (P<0.01). The results suggest that LPT is able to accelerate alveolar bone repair after molar extraction, leading to a more homogeneous trabecular configuration represented by thin and close trabeculae.

Histological analysis of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low-level laser therapy.

OBJECTIVE: The purpose of this research was to evaluate the histological changes of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low level laser therapy (LLLT). METHODS: The movement of the upper molar was performed in 60 male Wistar rats divided into four groups (n=15): CTR (control), DBT (diabetic), CTR/LT (irradiated control) and DBT/LT (irradiated diabetic). Diabetes was induced with alloxan (150 mg/kg, i.p.). LLLT was applied with GaAlAs laser at 780 nm (35 J/cm(2)). After 7, 13 and 19 days, the periodontal ligament and alveolar bone were histologically analyzed. RESULTS: The mean of osteoblasts (p<0.01) and blood vessels (p<0.05) were significantly decreased in DBT compared with CTR at 7 days, whereas the mean of osteoclasts was lower at 7 (p<0.001) and 13 days (p<0.05). In DBT/LT, only the mean of osteoclasts was lower than in CTR (p<0.05) at 7 days, but no difference was observed at 13 and 19 days (p>0.05). The collagenization of the periodontal ligament was impaired in DBT, whereas DBT/LLT showed density/disposition of the collagen fibers similar to those observed in CTR. CONCLUSIONS: LLLT improved the periodontal ligament and alveolar bone remodeling activity in diabetic rats during dental movement.

Effect of frequent application of low-level laser therapy on corticotomized tooth movement in dogs: a pilot study.

PURPOSE: The purposes of the present study were to evaluate the effects of frequent applications of low-level laser therapy (LLLT) on corticotomy-assisted tooth movement in a beagle dog model and to compare the effects in the mandible and maxilla. MATERIALS AND METHODS: In 4 male beagles, the maxillary and mandibular second premolars were extracted. The third premolars were corticotomized and then protracted from the canines with a continuous force of 200 g. Daily LLLT (using an aluminum gallium indium phosphide [AlGaInP] diode) was applied at the buccal mucosa of the corticotomized premolars on 1 side only. The tooth movement was measured for 8 weeks. Fluorochromes were injected intravenously at the start of the experiment (T0) and after 2 (T2), 4 (T4), and 8 (T8) weeks to evaluate new bone formation on the tension sides. Histomorphometric and immunohistologic evaluations were performed. RESULTS: In the mandible, the movement of the corticotomized premolars in the LLLT plus corticotomy group was less than that in the corticotomy-only group, although the difference was not statistically significant. In the maxilla, no significant differences between the 2 groups were found. Osteoclastic and proliferating cell activities and the amount of new bone formation were greater in the mandibular LLLT plus corticotomy group than in the corticotomy-only group. CONCLUSIONS: The frequent application of LLLT showed no significant effect on the corticotomized tooth movement.

Platelet-rich plasma, low-level laser therapy, or their combination promotes periodontal regeneration in fenestration defects: a preliminary in vivo study.

BACKGROUND: This study histomorphometrically analyzes the influence of platelet-rich plasma (PRP), low-level laser therapy (LLLT), or their combination on the healing of periodontal fenestration defects (PFDs) in rats. METHODS: PFDs were surgically created in the mandibles of 80 rats. The animals were randomly divided into four groups: 1) C (control) and 2) PRP, defects were filled with blood clot or PRP, respectively; 3) LLLT and 4) PRP/LLLT, defects received laser irradiation, were filled with blood clot or PRP, respectively, and then irradiated again. Animals were euthanized at either 10 or 30 days post-surgery. Percentage of new bone (NB), density of newly formed bone (DNB), new cementum (NC), and extension of remaining defect (ERD) were histomorphometrically evaluated. Data were statistically analyzed (analysis of variance; Tukey test, P <0.05). RESULTS: At 10 days, group PRP presented ERD significantly lower than group C. At 30 days, group PRP presented NB and DNB significantly greater than group C. Groups LLLT, PRP, and PRP/LLLT showed significant NC formation at 30 days, with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any group C specimen. CONCLUSIONS: LLLT, PRP, or their combination all promoted NC formation with a functional periodontal ligament. The combination PRP/LLLT did not show additional positive effects compared to the use of either therapy alone.

Influence of low-level laser on bone remodeling during induced tooth movement in rats.

OBJECTIVE: To analyze the effect of low-level laser on bone remodeling during induced tooth movement in rats. MATERIALS AND METHODS: A diode laser (808 nm, 100 mW, 54 J on an area of 0.0028 cm(2)) was used. The application was continuous, punctual, and with contact. Forty-two 70-day-old Wistar rats had the maxillary left first molar moved using a force level of 25 g. In two experimental subgroups the movement was performed over 7 days and in three subgroups the movement occurred over 14 days. In the 7-day movement subgroups, one subgroup received laser irradiation on day 1 only; the other subgroup received laser irradiation on days 1, 3, and 5. In the 14-day movement subgroups, one subgroup received laser irradiation on day 1 only; the second on days 1, 3, and 5; and the third on days 1, 3, 5, 7, 9, 11, and 13. The control group was also divided into two subgroups, and movement occurred over two different periods of treatment (7 days and 14 days) without laser application; these were used as controls for the respective experimental subgroups. Inter-subgroup comparison was performed with Kruskal-Wallis, followed by Mann-Whitney and analysis of variance, followed by Tukey tests within the 7- and 14-day subgroups. RESULTS: The subgroup with three laser applications showed significantly greater osteoclastic activity and bone resorption than the other subgroups in the 7-day movement subgroups. CONCLUSIONS: Low-level laser application significantly increased the osteoclastic but not the osteoblastic activity during the initial phases of tooth movement. In addition, the osteoclastic activity was dose-dependent.

Effect of laser phototherapy on the hyalinization following orthodontic tooth movement in rats.

OBJECTIVE: We aimed to assess histologic changes after the use of laser phototherapy (LPT) during induced tooth movement with 40 g/F on young adult male rats. BACKGROUND DATA: Hyalinization is a sterile necrosis at the pressure zone of the periodontal ligament observed during the initial stages of the orthodontic movement, and extensive hyaline areas might cause an important delay in the tooth movement. The use of LPT is considered an enhancement factor for bone repair, as it stimulates microcirculation as well as the cellular metabolism. MATERIALS AND METHODS: Thirty animals were divided into two groups (n=15), named according to the time of animal death (7, 13, and 19 days). Half of the animals in each group were subjected to irradiation with infrared (IR) laser (λ790 nm, round shaped beam, 40 mW, continuous wave (CW), diameter=2 mm (0.0314 cm(2)), 1.273 W/cm(2), time=2×112 sec+1×275 sec (total time 499 sec), 2×142.6/4.48 J+1×350/11 J, 635.2 J/cm(2)/20 J/ session), during orthodontic movement, the other half were used as nonirradiated controls. After animal death, specimens were sectioned, processed, and stained with hematoxylin and eosin (HE) and Sirius Red, and were used for semi-quantitative histologic analysis by light microscopy. Data were statistically analyzed. RESULTS: We demonstrated that LPT positively affected an important aspect of dental movement; the hyalinization. In the present study, we found a significant reduced expression of hyalinization after 19 days. On irradiated subjects, hyalinization was increased at day 7 with significant reduction at day 13. CONCLUSIONS: It is possible to conclude that the use of laser light caused histologic alterations during the orthodontic movement characterized by increased formation of areas of hyalinization at early stages, and late reduction when compared to nonirradiated animals.

Laser-induced alveolar bone changes during orthodontic movement: a histological study on rodents.

OBJECTIVE: The aim of this study was to assess by light microscopy changes in alveolar bone during orthodontic movement in rats. BACKGROUND: Orthodontic movement causes both removal and deposition of bone tissue. The use of laser phototherapy (LPT) is considered an enhancement factor for bone repair. METHODS: Thirty Wistar rats were divided into two groups (n = 15) and subdivided according to animal death (7,13, and 19 days). Half of the animals in each group were treated with LPT during orthodontic movement. After animal death, specimens were processed and underwent histological and semi-quantitative analyses (HE and Sirius red). RESULTS: LPT-irradiated specimens showed significantly higher numbers of osteoclasts when compared with controls at both 7 (p = 0.015) and 19 (p = 0.007) days, as well as significant increases in the number of osteoblasts (p = 0.015) between days 7 and 13. The amount of collagen matrix was significantly reduced between days 7 and 13 at both pressure and tension sites in controls (p = 0.015) but not in LPT-treated animals. LPT-treated subjects showed significantly greater deposition of collagen matrix at the pressure site at both the thirteenth (p = 0.007) and nineteenth days (p = 0.001). At the tension site, a significant increase in the amount of collagen matrix was observed in non-irradiated specimens (p = 0.048) between days 7 and 19. CONCLUSIONS: LPT caused significant histological changes in the alveolar bone during induced tooth movement, including alterations in the number of both osteoclasts and osteoblasts and in collagen deposition in both pressure and tension areas.

Low-energy laser irradiation facilitates the velocity of tooth movement and the expressions of matrix metalloproteinase-9, cathepsin K, and alpha(v) beta(3) integrin in rats.

It has previously been reported that low-energy laser irradiation stimulated the velocity of tooth movement via the receptor activator of nuclear factor kappa B (RANK)/RANK ligand and the macrophage colony-stimulating factor/its receptor (c-Fms) systems. Matrix metalloproteinase (MMP)-9, cathepsin K, and alpha(v) beta(3) [alpha(v)beta3] integrin are essential for osteoclastogenesis; therefore, the present study was designed to examine the effects of low-energy laser irradiation on the expression of MMP-9, cathepsin K, and alpha(v)beta3 integrin during experimental tooth movement. Fifty male, 6-week-old Wistar strain rats were used in the experiment. A total force of 10g was applied to the rat molars to induce tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moving tooth and, after 7 days, the amount of tooth movement was measured. To determine the amount of tooth movement, plaster models of the maxillae were made using a silicone impression material before (day 0) and after tooth movement (days 1, 2, 3, 4, and 7). The models were scanned using a contact-type three-dimensional (3-D) measurement apparatus. Immunohistochemical staining for MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 was performed. Intergroup comparisons of the average values were conducted with a Mann-Whitney U-test for tooth movement and the number of tartrate-resistant acid phosphatase (TRAP), MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3-positive cells. In the laser-irradiated group, the amount of tooth movement was significantly greater than that in the non-irradiated group at the end of the experiment (P < 0.05). Cells positively stained with TRAP, MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 were found to be significantly increased in the irradiated group on days 2-7 compared with those in the non-irradiated group (P < 0.05). These findings suggest that low-energy laser irradiation facilitates the velocity of tooth movement and MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 expression in rats.

Low-energy laser irradiation accelerates the velocity of tooth movement via stimulation of the alveolar bone remodeling.

INTRODUCTION: Previously, the authors have reported the acceleration of tooth movement and osteoclastogenesis on the pressure site in an experimental tooth movement model by low-energy laser irradiation (LELI), which stimulated the RANK/RANKL system and c-fms/macrophage colony-stimulating factor system. However, the effect of LELI on osteogenesis on the tension site is not known clearly. Moreover, the temporal changes in alveolar bone during tooth movement have not been investigated as yet. Therefore, the present study was designed to examine the effects of LELI on alveolar bone remodeling during experimental tooth movement, and observe the temporal bone mineral density (BMD) using micro-computed tomography (muCT). MATERIALS AND METHODS: To induce experimental tooth movement in rats, 10 g force was applied to the upper right first molar with Nickel titanium closed-coil. Next, a gallium-aluminum-arsenide (Ga-Al-As) diode laser was used to irradiate the area around the moved tooth, and BMD and the amount of tooth movement were measured by muCT scanning for 21 days. Histopathological examination was also performed. RESULTS: The amount of tooth movement in the LELI group was significantly greater than in the non-irradiation group by the end of the experimental period. Further, compared with the non-irradiation group, the fall of BMD was less in the LELI group. CONCLUSION: These findings suggest that LELI accelerates the velocity of tooth movement via stimulation of the alveolar bone remodeling.

Influence of low-level laser therapy on biomaterial osseointegration: a mini-review.

The aim of this paper is to provide an overview of the available literature on low-level laser therapy (LLLT) and its influence on bone repair and the osseointegration of biomaterials. Extensive studies of alveolar bone repair, a common problem in periodontal therapy, have been conduced worldwide. The utility of LLLT in biomaterial osseointegration is still unanswered, due to lack of literature and poorly understood mechanisms. It is still difficult for one to compare studies about the action of LLLT on the osseointegration of biomaterials because the experimental models and duration of treatments are very distinct. However, it could be concluded that LLLT may offer advantages in terms of periodontal and bone functional recovery and biomaterial osseointegration.

Effects of Nd:Yag laser irradiation on osteoblast cell cultures.

The application of Nd:YAG lasers in endodontics has been explored by many investigators for different purposes. The aim of this in vitro study is to evaluate the effects of Nd:YAG laser on osteoblast cell cultures. A 1,064 nm Nd:YAG laser was used to irradiate human osteoblast-like cells (Saos-2) in noncontact mode for 10 s with different energy settings. The settings varied were pulse energy (20-120 mJ), pulse repetition rate (10-30 Hz), and power output (0.2-3.6 W). He-Ne, the aiming beam of Nd:YAG laser, was used in noncontact mode for 10 s. After 7-, 14-, and 21-day incubation period, cell viability and proliferation were evaluated with methylthiazoletetrazolium (MTT) colorometric method. The comparison of average MTT values gave no statistically significant difference between 20 mJ, 10 Hz, He-Ne, and control (p < 0.05). The differences between all other groups were significant (p < 0.05). Increase in the pulse energy, pulse repetition rate, and power output has a negative effect on the cell viability and proliferation.

Oral implant rehabilitation in irradiated patients without adjunctive hyperbaric oxygen.

In 15 patients treated for malignant tumors in the maxillofacial region, 90 Brånemark implants have been placed in irradiated alveolar bone without adjunctive hyperbaric oxygen therapy. Seventy-eight implants were placed in the mandible and 12 in the maxilla. After a follow-up period of 1 to 8 years, 88 implants are still stable, 27 after 6 to 8 years, 44 after 3 to 4 years, and 17 after 1 to 2 years. Two patients lost 1 implant each, both at an early stage. The success rate is 97.8% according to remaining implants, and prosthesis stability is 100%. Implant treatment for oral rehabilitation can be carried out as a safe and successful procedure in the irradiated patient without adjunctive hyperbaric oxygen therapy.

Postradiation dental extractions without hyperbaric oxygen.

This study examined the incidence of osteoradionecrosis after tooth extraction with low-epinephrine or epinephrine-free, nonlidocaine local anesthetics and conservative surgical techniques. Estimates of the absorbed radiation dose on irradiated alveolar bone were made by reviewing radiotherapy records. This investigation included 72 patients ranging in age from 22 to 80 years (median 57.4 years). We removed 449 teeth. Analysis of radiotherapy check films revealed that only 196 teeth (44%) were included within the treatment volume. The median prescribed tumor dose was 50 Gy (range 25 to 84 Gy) in 20 fractions (range 10 to 37), with a median dose per fraction of 2.5 Gy (range 1.88 to 3.14 Gy). Follow-up time ranged from 68 days to 19.3 years (median 4.8 years). No instances of osteoradionecrosis occurred as a result of dental extraction with this conservative method.