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The ultimate goal of periodontal therapy is to repair the damaged periodontal supporting tissues, permitting regeneration of the periodontal ligament. However, the cell response, the supportive matrix and the bioactive molecules use have not yet been well established. Bone marrow mononuclear cells were extracted from rat femurs and tibiae and cultured on a cross-linked collagen membrane, bone graft, or molar tooth to compare cell attachment and early proliferation on these materials. Cell attachment was quantified by light microscopy at 24, 48 and 72h, and cell proliferation was observed under a SEM after 72h. After 24h, the number of cells on bone graft was similar to that of the control and more than twice compared to collagen membrane (q=7.473 p<0.001) and 1.75 times greater than with tooth cementum (q=5.613 p<0.01). However, the number of cells close to bone graft decreased in the second day compared to the control. SEM examination revealed a significant decrease in the number of cells that attached and proliferated on tooth and bone graft when compared with membrane. The results showed that bone marrow mesenchymal cells offer great potential for colonize a collagen membrane.

El objetivo último de la terapia periodontal es reparar el daño tejidos periodontales de soporte, permitiendo la regeneración del ligamento periodontal. Sin embargo, la respuesta de la célula, la matriz de apoyo y las moléculas bioactivas aún no han sido bien establecidas. Células mononucleares de la médula ósea se extrajeron del fémur y fibula de rata, y fueron cultivadas sobre un reticulado de membrana de colágeno, de injerto de hueso o de un diente molar para comparar la adhesión celular y la proliferación temprana sobre estos materiales. La adhesión celular fue cuantificada por microscopía de luz a las 24, 48 y 72h, y la proliferación celular fue observada bajo MEB después de 72h. Después de 24 horas, el número de células sobre el injerto de hueso fue similar a la del control y más del doble en comparación con la membrana de colágeno (q=7,473 p<0,001) y 1,75 veces mayor que con el cemento dental (q=5,613 p<0,01). Sin embargo, el número de células cerca del injerto óseo disminuyó el segundo día en comparación con el control. El examen al MEB reveló una disminución significativa en el número de células que se unen y proliferan sobre los dientes y el injerto óseo en comparación con la membrana. Los resultados mostraron que las células mesenquimales de la médula ósea tienen un gran potencial para colonizar la membrana de colágeno.

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BACKGROUND: To investigate the effects of low-intensity exercise on bone healing during a short time. MATERIAL/METHODS: We made a surgical 1-mm perforation in the upper third medial cortical of the right tibia of 45 male Wistar rats (3 months old; mean weight, 282+/-34 g). Animals were randomly assigned to a swimming exercise group (SWIM, n=15), a running exercise group (RUN, n=15), or a no exercise control group (CON, n=15). Treatment sessions (10 minutes/day, 5 days/week) were done for 7, 14, or 21 days. Tibias were removed for radiographic, morphometric, and stereologic analyses. Blood samples were obtained for biochemical analyses. RESULTS: Serum phosphorus levels were higher in animals in the RUN group compared with animals in the SWIM group on the seventh day. On the 14th day, the tibias of the animals in the SWIM and RUN groups exhibited higher radiopacity in radiographic grades than animals in the CON group. No difference in collagen morphometry was verified. On the 21st day, serum alkaline phosphatase levels were higher in animals in the CON group than they were in the exercise groups, and animals in the SWIM and CON groups demonstrated an increase in newly formed bone in comparison to animals in the RUN group. CONCLUSIONS: At the 14th day of treatment, weight-bearing exercise, assessed by radiography, was found to be beneficial for bone healing. Results at the 21st day of treatment further supported the benefits of non-weight-bearing exercises, showing that weight-bearing exercise may improve bone repair in rats.

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This study evaluated pulp changes in molars of rats submitted to tooth movement by application of a 0.4 N force. Twenty-five adult male Wistar rats (Rattus norvegicus, albinus) were randomly assigned to 5 groups (n=5), being one control group not submitted to force application, and four study groups of 6, 12, 24 and 72 h of force application. The study groups received a 5-mm long nickel-titanium closed coil spring, placed from the right maxillary first molar to the maxillary incisors of each animal. The coil spring was used for mesial inclination of the first molar. After the specific period of tooth movement of each study group, the animals were sacrificed and specimens containing the teeth submitted to movement were processed and stained with hematoxylin and eosin for histological analysis under light microscopy. The results demonstrated alteration of the odontoblastic layer, with hypertrophy of odontoblasts especially at the mesial area of the coronal pulp, edema of the pulp connective tissue in the central area of the pulp, and vascular alteration with accumulation of erythrocytes and leukocytes inside the vessels, especially at the mesial root of the moved teeth. These changes were less remarkable for the 72-h period. Thus, it may be concluded that tooth movement yielded pulpal tissue alterations compatible with an inflammatory process, which are reversible if the aggression is not more intense than the physiological limit of tissue tolerance.

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This study evaluated pulp changes in molars of rats submitted to tooth movement by application of a 0.4 N force. Twenty-five adult male Wistar rats (Rattus norvegicus, albinus) were randomly assigned to 5 groups (n=5), being one control group not submitted to force application, and four study groups of 6, 12, 24 and 72 h of force application. The study groups received a 5-mm long nickel-titanium closed coil spring, placed from the right maxillary first molar to the maxillary incisors of each animal. The coil spring was used for mesial inclination of the first molar. After the specific period of tooth movement of each study group, the animals were sacrificed and specimens containing the teeth submitted to movement were processed and stained with hematoxylin and eosin for histological analysis under light microscopy. The results demonstrated alteration of the odontoblastic layer, with hypertrophy of odontoblasts especially at the mesial area of the coronal pulp, edema of the pulp connective tissue in the central area of the pulp, and vascular alteration with accumulation of erythrocytes and leukocytes inside the vessels, especially at the mesial root of the moved teeth. These changes were less remarkable for the 72-h period. Thus, it may be concluded that tooth movement yielded pulpal tissue alterations compatible with an inflammatory process, which are reversible if the aggression is not more intense than the physiological limit of tissue tolerance.

Este estudo avaliou alterações pulpares em molares de ratos movimentados com amplitude de força de 0,4 N. Vinte e cinco ratos machos adultos Wistar (Rattus norvegicus, albinus) foram aleatoriamente alocados em 5 grupos (n=5), sendo 1 grupo controle não submetido à aplicação de força, e 4 grupos teste submetidos a 6, 12, 24 e 72 h de aplicação de força. Os grupos teste receberam uma mola fechada tipo coil spring de níquel-titânio com 5 mm de comprimento, fixada do primeiro molar superior direito até os incisos superiores do animal. A mola tipo coil spring foi utilizada para mesialização do primeiro molar. Após o período específico de movimentação de cada grupo experimental, os animais foram sacrificados e as peças contendo o dente movimentado e o seu tecido pulpar foram processadas e coradas com hematoxilina e eosina para análise histológica em microscopia de luz. Os resultados mostraram alteração da camada de odontoblastos com hipertrofia dessas células, principalmente na região mesial da polpa coronária; edema no tecido conjuntivo pulpar, evidenciado na região central da polpa; alteração vascular, com acúmulo de eritrócitos e leucócitos dentro da luz dos vasos, principalmente na raiz mesial do dente movimentado. Essas alterações foram menos evidentes no período de 72 h. Dessa forma, conclui-se que o movimento dentário provoca alterações pulpares teciduais compatíveis com processo inflamatório, as quais são reversíveis se a agressão não ultrapassar o limite de tolerância do tecido.

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Any alteration in blood flow or vascular pressure caused by a trauma may damage the pulp tissue. The aim of this study was to evaluate the vascular changes during the initial period of tooth movement. These alterations were assessed in coronal molar pulp tissue of 20 male Wistar rats, 90 days of age, submitted to mesial inclination movement by a closed coil spring, placed from the right maxillary first molar to the maxillary incisors. The animals were divided into three experimental groups of 6, 24, and 72 hours of 0.4 N force application, with five animals in each group, and a control group of five animals without tooth movement. The volume density of blood vessels (V(v)) of the coronal pulp tissue in the experimental groups was calculated by stereology and compared with the control group. The results demonstrated a significant increase in V(v) at 6 hours of 10.2 per cent compared with 7.2 per cent for the control group (P 0.05). These results demonstrate the high capacity of adaptation of the pulp tissue to an aggression, provided the biological limits of tolerance of the pulp are respected.

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