RESUMO
This study investigated the effects of photobiomodulation (PBM) on upper molar intrusion movement, regarding acceleration of orthodontic movement and its molecular effects. The sample consisted of 30 patients with indication of tooth intrusion for oral rehabilitation. Teeth were divided into three different groups: G1 (n = 10) pre-molars without force or laser application (control); G2 (n = 10) upper molar intrusion; and G3 (n = 10) upper molar intrusion and PBM. On PBM treated molars, the teeth were irradiated with a low-power diode laser (808 nm, 100 mW), receiving 1 J per point, density of 25 J/cm2 , with application of 10 s per point, 10 points (5 per vestibular and 5 per palatal region). Orthodontic force of intrusion applied every 30 days and PBM was performed immediately, 3 and 7 days after force application for 3 months. Gingival crevicular fluid was collected at the same time periods as the laser applications and interleukins (IL) 1-ß, -6 and -8 were evaluated by enzyme-linked immunosorbent assay. Clinical measures were performed monthly to verify the amount of intrusion. The levels of IL-6, IL-8 and IL-1ß increased under orthodontic force (G2 and G3) when compared to control group (G1), however, the cytokines levels were significantly higher after PBM (G3). The mean intrusion velocity was 0.26 mm/month in the irradiated group (G3), average duration of 8 months vs 0.17 mm/month for the non-irradiated group (G2), average duration of 12 months. This study suggests that PBM accelerates tooth movement during molar intrusion, due to modulation of IL-6, IL-8 and IL-1ß during bone remodeling.
Assuntos
Remodelação Óssea/efeitos da radiação , Regulação da Expressão Gênica/efeitos da radiação , Interleucinas/metabolismo , Terapia com Luz de Baixa Intensidade , Técnicas de Movimentação Dentária , Adulto , Idoso , Feminino , Humanos , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Masculino , Pessoa de Meia-IdadeRESUMO
This study evaluated the biological effects of low-level laser therapy (LLLT) on bone remodeling, tooth displacement and root resorption, occurred during the orthodontic tooth movement. Upper first molars of a total of sixty-eight male rats were subjected to orthodontic tooth movement and euthanized on days 3, 6, 9, 14 and 21 days and divided as negative control, control and LLLT group. Tooth displacement and histomorphometric analysis were performed in all animals; scanning electron microscopy analysis was done on days 3, 6 and 9, as well as the immunohistochemistry analysis of RANKL/OPG and TRAP markers. Volumetric changes in alveolar bone were analyzed using MicroCT images on days 14 and 21. LLLT influenced bone resorption by increasing the number of TRAP-positive osteoclasts and the RANKL expression at the compression side. This resulted in less alveolar bone and hyalinization areas on days 6, 9 and 14. LLLT also induced less bone volume and density, facilitating significant acceleration of tooth movement and potential reduction in root resorption besides stimulating bone formation at the tension side by enhancing OPG expression, increasing trabecular thickness and bone volume on day 21. Taken together, our results indicate that LLLT can stimulate bone remodeling reducing root resorption in a rat model. LLLT improves tooth movement via bone formation and bone resorption in a rat model.
Assuntos
Remodelação Óssea/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Reabsorção da Raiz/radioterapia , Técnicas de Movimentação Dentária , Animais , Masculino , Dente Molar , Osteoclastos/efeitos da radiação , Ligante RANK/metabolismo , Ratos , Reabsorção da Raiz/prevenção & controleRESUMO
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.
Assuntos
Perda do Osso Alveolar/etiologia , Processo Alveolar/efeitos da radiação , Remodelação Óssea/efeitos da radiação , Lasers Semicondutores/uso terapêutico , Terapia com Luz de Baixa Intensidade/efeitos adversos , Técnicas de Movimentação Dentária/instrumentação , Análise de Variância , Animais , Feminino , Terapia com Luz de Baixa Intensidade/instrumentação , Terapia com Luz de Baixa Intensidade/métodos , Osteoblastos/citologia , Osteoblastos/efeitos da radiação , Osteoclastos/citologia , Osteoclastos/efeitos da radiação , Ratos , Ratos Wistar , Técnicas de Movimentação Dentária/métodosRESUMO
This study evaluated protection by selenium (Se) in the bone repair process in ovariectomized rats after irradiation. For such purpose, 80 ovariectomized female Wistar rats were randomly divided into 4 experimental groups: ovariectomized (Ov), Ov/Se, Ov/irradiated (Irr) and Ov/ Se/Irr. A bone defect was created on the tibia of all animals 40 days after ovariectomy. Two days after surgery, only the Ov/Se and Ov/Se/Irr rats received 0.8 mg Se/kg. Three days after surgery, only the Ov/Irr and Ov/Se/Irr rats received 10 Gy of x-rays on the lower limb region. The animals were euthanized at 7, 14, 21 and 28 days after surgery to assess the repair process, which was evaluated by analysis of trabecular bone number (Masson Trichrome) and birefringence analysis (Picrosirius). It was possible to observe a delay in the bone repair process in the ovariectomized/irradiated group and similarity between the ovariectomized, Ov/Se and Ov/Se/Irr groups. In conclusion, sodium selenite exerted a radioprotective effect in the bone repair of tibia of ovariectomized rats without toxicity.
Assuntos
Antioxidantes/uso terapêutico , Regeneração Óssea/efeitos dos fármacos , Ovariectomia , Protetores contra Radiação/uso terapêutico , Ácido Selenioso/uso terapêutico , Tíbia/efeitos dos fármacos , Animais , Compostos Azo , Densidade Óssea/efeitos dos fármacos , Densidade Óssea/efeitos da radiação , Doenças Ósseas/fisiopatologia , Regeneração Óssea/efeitos da radiação , Remodelação Óssea/efeitos dos fármacos , Remodelação Óssea/efeitos da radiação , Corantes , Amarelo de Eosina-(YS) , Feminino , Processamento de Imagem Assistida por Computador/métodos , Verde de Metila , Doses de Radiação , Distribuição Aleatória , Ratos , Ratos Wistar , Tíbia/efeitos da radiação , Fatores de TempoRESUMO
This studyevaluated protection by selenium (Se) in the bone repair process in ovariectomized rats after irradiation. For such purpose, 80 ovariectomized female Wistar rats were randomly divided into 4 experimental groups: ovariectomized (Ov), Ov/Se, Ov/irradiated (Irr) and Ov/ Se/Irr. A bone defect was created on the tibia of all animals 40 days after ovariectomy. Two days after surgery, only the Ov/Se and Ov/Se/Irr rats received 0.8 mg Se/kg. Three days after surgery, only the Ov/Irr and Ov/Se/Irr rats received 10 Gy of x-rays on the lower limb region. The animals were euthanized at 7, 14, 21 and 28 days after surgery to assess the repair process, which was evaluated by analysis of trabecular bone number (Masson Trichrome) and birefringence analysis (Picrosirius). It was possible to observe a delay in the bone repair process in the ovariectomized/irradiated group and similarity between the ovariectomized, Ov/Se and Ov/Se/Irr groups. In conclusion, sodium selenite exerted a radioprotective effect in the bone repair of tibia of ovariectomized rats without toxicity.
Esse estudo avaliou a proteção do selênio no processo de reparação óssea em ratas ovariectomizadas após irradiação. Para isso, 80 ratas Wistar foram divididas aleatoriamente em 4 grupos experimentais: ovariectomizado, ovariectomizado/selênio, ovariectomizado/irradiado e ovariectomizado/selênio/irradiado. Foi realizado um defeito ósseo na tíbia de todos os animais 40 dias após ovariectomia. Dois dias após essa cirurgia, os animais dos grupos ovariectomizado/selênio e ovariectomizado/selênio/irradiado receberam 0,8 mg Se/kg. Três dias após a cirurgia, os animais dos grupos ovariectomizado/irradiado e ovariectomizado/selênio/irradiado receberam 10 Gy de radiação X na região de membros inferiores. Os animais foram sacrificados 7, 14, 21 e 28 dias após a cirurgia para avaliação do processo de reparo ósseo, que foi realizado pela análise do número de trabéculas ósseas (coloração Tricrômico de Masson) e pela análise de birrefringência (coloração de Picrosirius). Foi observado atraso no processo de reparo ósseo no grupo ovariectomizado/irradiado e semelhança entre os grupos ovariectomizado, ovariectomizado/selênio e ovariectomizado/selênio/irradiado. Foi possível concluir que o selenito de sódio exerceu efeito radioprotetor no processo de reparação de tíbias em ratas ovariectomizadas sem toxicidade.
Assuntos
Animais , Feminino , Ratos , Antioxidantes/uso terapêutico , Regeneração Óssea/efeitos dos fármacos , Ovariectomia , Protetores contra Radiação/uso terapêutico , Ácido Selenioso/uso terapêutico , Tíbia/efeitos dos fármacos , Compostos Azo , Densidade Óssea/efeitos dos fármacos , Densidade Óssea/efeitos da radiação , Doenças Ósseas/fisiopatologia , Regeneração Óssea/efeitos da radiação , Remodelação Óssea/efeitos dos fármacos , Remodelação Óssea/efeitos da radiação , Corantes , Amarelo de Eosina-(YS) , Processamento de Imagem Assistida por Computador/métodos , Verde de Metila , Doses de Radiação , Distribuição Aleatória , Ratos Wistar , Fatores de Tempo , Tíbia/efeitos da radiaçãoRESUMO
OBJECTIVE: This study investigated the effects of low-level laser therapy (LLLT) and electrical stimulation (ES) on bone loss in spinal cord-injured rats. MATERIALS AND METHODS: Thirty-seven male Wistar rats were divided into four groups: standard control group (CG); spinal cord-injured control (SC); spinal cord-injured treated with laser (SCL; GaAlAs, 830 nm, CW, 30 mW/cm, 250 J/cm(2)); and spinal cord-injured treated with electrical field stimulation (SCE; 1.5 MHz, 1:4 duty cycles, 30 mW, 20 min). Biomechanical, densitometric, and morphometric analyses were performed. RESULTS: SC rats showed a significant decrease in bone mass, biomechanical properties, and morphometric parameters (versus CG). SCE rats showed significantly higher values of inner diameter and internal and external areas of tibia diaphyses; and the SCL group showed a trend toward the same result (versus SC). No increase was found in either mechanical or densitometric parameters. CONCLUSION: We conclude that the mentioned treatments were able to initiate a positive bone-tissue response, maybe through stimulation of osteoblasts, which was able to determine the observed morphometric modifications. However, the evoked tissue response could not determine either biomechanical or densitometric modifications.
Assuntos
Remodelação Óssea/fisiologia , Terapia por Estimulação Elétrica/métodos , Terapia com Luz de Baixa Intensidade/métodos , Osteoporose/prevenção & controle , Traumatismos da Medula Espinal/terapia , Análise de Variância , Animais , Fenômenos Biomecânicos , Densidade Óssea , Remodelação Óssea/efeitos da radiação , Osso e Ossos/patologia , Osso e Ossos/efeitos da radiação , Densitometria , Modelos Animais de Doenças , Imuno-Histoquímica , Masculino , Osteoporose/diagnóstico , Osteoporose/etiologia , Distribuição Aleatória , Ratos , Ratos Wistar , Valores de Referência , Traumatismos da Medula Espinal/complicaçõesRESUMO
PURPOSE: The purpose of the present study was to investigate whether osseointegration of HA-coated implants can be affected by irradiation. MATERIALS AND METHODS: A single dose of 15 Gy was applied to the right tibia of 5 rabbits and the left tibia was not irradiated and used as control. After 3 months, the animals were killed and the quantification of the implant-bone contact surfaces was performed using scanning electron micrographs of the resin sections containing the implants in the irradiated and nonirradiated bones. After the healing period, all implants were stable. RESULTS: The results show a mean percentage of bone-implant contact of 45.52% in the irradiated tissue and 47.56% in the nonirradiated tissue, with no statistic significant difference (P > 0.05). CONCLUSION: In conclusion, radiotherapy may not interfere with osseointegration process around HA-coated implants in rabbit cortical bone.
Assuntos
Remodelação Óssea/efeitos da radiação , Materiais Revestidos Biocompatíveis , Implantação Dentária Endóssea , Implantes Dentários , Durapatita , Osseointegração , Osteorradionecrose , Animais , Planejamento de Prótese Dentária , Feminino , Coelhos , TíbiaRESUMO
BACKGROUND AND OBJECTIVES: Bone remodeling is characterized as a cyclic and lengthy process. It is currently accepted that not only this dynamics is triggered by a biological process, but also biochemical, electrical, and mechanical stimuli are key factors for the maintenance of bone tissue. The hypothesis that low-level laser therapy (LLLT) may favor bone repair has been suggested. The purpose of this study was to evaluate the bone repair in defects created in rat lower jaws after stimulation with infrared LLLT directly on the injured tissue. STUDY DESIGN/MATERIALS AND METHODS: Bone defects were prepared on the mandibles of 30 Holtzman rats allocated in two groups (n = 15), which were divided in three evaluation period (15, 45, and 60 days), with five animals each. control group-no treatment of the defect; laser group-single laser irradiation with a GaAlAs semiconductor diode laser device (lambda = 780 nm; P = 35 mW; t = 40 s; Theta = 1.0 mm; D = 178 J/cm(2); E = 1.4 J) directly on the defect area. The rats were sacrificed at the pre-established periods and the mandibles were removed and processed for staining with hematoxylin and eosin, Masson's Trichrome and picrosirius techniques. RESULTS: The histological results showed bone formation in both groups. However, the laser group exhibited an advanced tissue response compared to the control group, abbreviating the initial inflammatory reaction and promoting rapid new bone matrix formation at 15 and 45 days (P<0.05). On the other hand, there were no significant differences between the groups at 60 days. CONCLUSION: The use of infrared LLLT directly to the injured tissue showed a biostimulating effect on bone remodeling by stimulating the modulation of the initial inflammatory response and anticipating the resolution to normal conditions at the earlier periods. However, there were no differences between the groups at 60 days.
Assuntos
Remodelação Óssea/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Mandíbula/efeitos da radiação , Traumatismos Mandibulares/terapia , Animais , Masculino , Mandíbula/patologia , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVE: The aim of the present study was to assess histologically the effect of low-level laser thrapy (LLLT) (lambda 830 nm) on the healing of bone defects associated with autologous bone graft. BACKGROUND DATA: LLLT has been used on the modulation of bone healing because of the photo-physical and photochemical properties of some wavelengths. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect on the healing bone. METHODS: Sixty male Wistar rats were divided into four groups: G1 (control), G2 (LLLT on the surgical bed), G3 (LLLT on the graft), and G4 (LLLT on both the graft and the surgical bed). The dose per session was 10 J/cm(2), and it was applied to the surgical bed (G2/G4) and on the bone graft (G3/G4). LLLT was carried out every other day for 15 days (lambda 830 nm, phi = 0.5 cm(2), 50 Mw, 10 J/cm(2)). The dose was fractioned in four points. The animals were sacrificed 15, 21, and 30 days after surgery; specimens were taken and routinely processed (wax, cut, and stain with H&E and Sirius red stains). Light microscopic analysis was performed by a pathologist. RESULTS: In the groups in which the LLLT was used trans-operatively on the surgical bed (G2/G4), bone remodeling was both quantitatively and qualitatively more evident when compared to subjects of groups G1 and G3. CONCLUSION: The present study indicates that the use of LLLT trans-operatively resulted in a positive biomodulative effect on the healing of bone defects associated with autologous bone grafts.
Assuntos
Remodelação Óssea/efeitos da radiação , Fêmur/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Animais , Transplante Ósseo , Fêmur/transplante , Masculino , Ratos , Ratos Wistar , Transplante AutólogoRESUMO
PURPOSE: To investigate the influence of 650 nm GaAlAs laser on the action of bone morphogenetic protein (BMP) in bone defects produced in rat femurs. METHODS: The sample consisted of 12 male albino Wistar rats (Rattus norvegicus). The animals were randomly divided into four experimental groups. After undergoing anesthesia, the fur was removed from the lateral face of the right thigh and surgical dissection was performed to view the femur region. A bone defect was created using a spherical diamond-tipped drill bit. In groups 1 and 2, the defect was filled with a paste of Gen-Tech bone-inducing substance. The animals were treated with GaAlAs laser, at a predetermined dose of joules/cm(2) for 80 seconds, over an area of 1 cm(2). Groups 2 and 4 were used as controls. Bone samples were removed to perform histological procedures and morphometric analyses on the 7th, 14th and 21st days after the operation. The results obtained were subjected to statistical analysis using ANOVA variance according to two criteria, with four repetitions, followed by the post hoc t test. The rejection level for the nullity hypothesis was 0.05 or 5% (alpha < or = 0.05). RESULTS: In comparisons between G1, G2, G3 and G4, p = 0.024 was observed. In statistical comparisons using the t test for paired samples, only G1 vs. G4 presented a statistically significant result (p = 0.021). CONCLUSION: The association of low-power laser application and Gen-Tech bone-inducing substance achieved a better result than laser application alone or BMP use alone.
Assuntos
Proteínas Morfogenéticas Ósseas/efeitos da radiação , Remodelação Óssea/efeitos da radiação , Fêmur/efeitos da radiação , Lasers Semicondutores/uso terapêutico , Terapia com Luz de Baixa Intensidade , Osteoblastos/efeitos da radiação , Animais , Modelos Animais de Doenças , Fêmur/patologia , Masculino , Osteoblastos/patologia , Ratos , Ratos WistarRESUMO
PURPOSE:To investigate the influence of 650 nm GaAlAs laser on the action of bone morphogenetic protein (BMP) in bone defects produced in rat femurs. METHODS: The sample consisted of 12 male albino Wistar rats (Rattus norvegicus). The animals were randomly divided into four experimental groups. After undergoing anesthesia, the fur was removed from the lateral face of the right thigh and surgical dissection was performed to view the femur region. A bone defect was created using a spherical diamond-tipped drill bit. In groups 1 and 2, the defect was filled with a paste of Gen-Tech bone-inducing substance. The animals were treated with GaAlAs laser, at a predetermined dose of joules/cm² for 80 seconds, over an area of 1 cm². Groups 2 and 4 were used as controls. Bone samples were removed to perform histological procedures and morphometric analyses on the 7th, 14th and 21st days after the operation. The results obtained were subjected to statistical analysis using ANOVA variance according to two criteria, with four repetitions, followed by the post hoc t test. The rejection level for the nullity hypothesis was 0.05 or 5 percent (alpha <= 0.05). RESULTS: In comparisons between G1, G2, G3 and G4, p = 0.024 was observed. In statistical comparisons using the t test for paired samples, only G1 vs. G4 presented a statistically significant result (p = 0.021). CONCLUSION: The association of low-power laser application and Gen-Tech bone-inducing substance achieved a better result than laser application alone or BMP use alone.
OBJETIVO: Este trabalho tem como objetivo estudar comparativamente a influência do laser AsGaAl de 650nm sobre a ação das proteínas morfogenéticas ósseas( BMP) em defeitos ósseos produzidas em fêmures de ratos. METODOLOGIA: Utilizamos uma amostra composta por 12 ratos machos (Rattus norvegicus), de linhagem Wistar albino, mantidos confinados em caixas com temperatura ambiente constante e iluminação adequada. Os animais foram divididos aleatoriamente em 4 grupos experimentais. Após o procedimento anestésico, foi realizada a retirada dos pelos da face lateral da coxa direita, seguida de procedimento cirúrgico para permitir a visualização da região. Foi realizado um defeito ósseo empregando brocas diamantadas do tipo esférica. Nos grupos 1 e 2 o defeito foi preenchido com uma pasta formada por substância osteoindutora Gen - Tech. Os animais foram tratados com o Laser GaAlAs, com dose pré-determinada de 4 joules/cm² e tempo de 80 segundos para uma área de 1cm². Os grupos 2 e 4 foram adotados como grupo-controle. As amostras do osso foram retiradas para realização de procedimento histológico e análise morfométrica nos 7°,14°e 21° dias de pós-operatório. Os resultados obtidos foram submetidos à análise estatística pela variância ANOVA segundo dois critérios, com quatro repetições. Seguido do post hoc test de t teste, com nível de rejeição da hipótese de nulidade de 0,05 ou 5 por cento (alfa <= 0,05). RESULTADOS: Na comparação entre G1, G2, G3 e G4, observou-se: (P = 0,024) e durante a comparação estatística através do teste "t" para amostras pareadas apenas o cruzamento entre Grupo 1 vs. o Grupo 4 apresentou, resultado estatisticamente significante com (p=0,021). CONCLUSÃO: Concluímos que a associação da aplicação do laser de baixa potência e a substância osteoindutora Gen Tech alcançou melhor resultado do que do que a aplicação de laser ou apenas o uso das BMPs.
Assuntos
Animais , Masculino , Ratos , Proteínas Morfogenéticas Ósseas/efeitos da radiação , Remodelação Óssea/efeitos da radiação , Fêmur/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Lasers Semicondutores/uso terapêutico , Osteoblastos/efeitos da radiação , Modelos Animais de Doenças , Fêmur/patologia , Osteoblastos/patologia , Ratos WistarRESUMO
Low-level laser therapy (LLLT) is increasingly being used in the regeneration of soft tissue. In the regeneration of hard tissue, it has already been shown that the biomodulation effect of lasers repairs bones more quickly. We studied the activity in bone cells after LLLT close to the site of the bone injury. The femurs of 48 rats were perforated (24 in the irradiated group and 24 in the control group) and the irradiated group was treated with a GaAlAs laser of 660 nm, 10 J/cm2 of radiant exposure on the 2nd, 4th, 6th and 8th days after surgery (DAS). We carried out histomorphometry analysis of the bone. We found that activity was higher in the irradiated group than in the control group: (a) bone volume at 5 DAS (p=0.035); (b) osteoblast surface at 15 DAS (p=0.0002); (c) mineral apposition rate at 15 and 25 DAS (p=0.0008 and 0.006); (d) osteoclast surface at 5 DAS and 25 DAS (p=0.049 and p=0.0028); and (e) eroded surface ( p=0.0032). We concluded that LLLT increases the activity in bone cells (resorption and formation) around the site of the repair without changing the bone structure.
Assuntos
Remodelação Óssea/efeitos da radiação , Fêmur/patologia , Fêmur/efeitos da radiação , Terapia com Luz de Baixa Intensidade , Osteoblastos/efeitos da radiação , Osteoclastos/efeitos da radiação , Animais , Arsenicais , Modelos Animais de Doenças , Fêmur/lesões , Gálio , Masculino , Osteoblastos/fisiologia , Osteoclastos/fisiologia , Ratos , Ratos WistarRESUMO
Acute and chronic uranium intoxication leads to the inhibition of bone formation and impaired bone modeling and remodeling. As these are processes directly involved in bone growth the aim of this paper is to present a biometric study of bone growth--tibiae and mandibles of rats intoxicated with uranium. Wistar ratios weighing 60-80 g were used as follows, a) one intraperitoneal injection (IPI, 2 mg/Kg of body weight)) of uranyl nitrate; b) 30 daily applications on the dorsal skin of aliquots of a mixture of U308, concentrated at 2% and at 4%--percutaneous absorption(PA)-. Tibia and mandible length were smaller in both experimental groups than in their respective controls. Some of the mandibular parameters were lower in intoxicated animals than their controls which in turn results in the alteration of the mandibular shape. We conclude that impairment in bone growth can be achieved by uranium intoxication.