02► ESTUDIO DE LA DINÁMICA ÓSEA MANDIBULAR Y DE LOS PROCESOS REABSORTIVOS DE LA CRESTA ALVEOLAR EN RATAS DIABÉTICAS Y CONTROLES

Periodontal illness is an inflammatory reaction of the periodontal tissue to the bacteria in the dental plaque.In order to assess the mandibular growth and describe the development of rats’ “spontaneous” periodontal illness, control animals line “m” were employed. The findings observed were corroborated against two experimental models (experimental diabetes and bisphosphonates). The experimental diabetes model was explored, because diabetes is considered an aggravating factor of periodontal illness. A therapeutic assay was carried out with bisphosphonates, which are highly recognized drugs for their antiosteoclastic effect. Periodontal illness can be considered an illness of the bone metabolism, given the typical bone resorption.In control rats, mandible growth matched body growth. Diabetes had an adverse effect on body growth which did not show in dry weight, density or mandible volume. In comparison with the control animals, animals treated with lidadronate (IG-9402) revealed a significant increase in dry weight and mandible volume. These results are consistent with such drugs’ well-known antiresorptive effect.The distance between the amelo-cementum junction and the alveolar bone crest (LAC-COA) increased as time elapsed, and it was bigger on the lingual side than on the vestibular side, in control animals, in diabetic animals and in animals treated with bisphosphonates. Measurement of the supporting periodontal bone (HPS) has not proved to be a useful means to assess periodontal illness during the rat’s fast-growing period.Periodontal illness appeared after weaning, and developed towards the 6th or 7th week after birth, with no signs of pathological alteration of the gingival tissue.In diabetic animals, there was a bigger number of focuses with lower total area in the resorption involved. Lower bone turnover, as well as the likely immunological tolerance to the usual food and mouth germs, account for this observation. The mineral density of the periodontal bone with no pathology was, on average, 34% lower in comparison with the control animals. The mineral density of the periodontal bone in resorption was also significantly lower.Equal doses of two bisphosphonates did not produce equal results. Lidadronate reduced the total area in resorption. Olpadronate significantly increased the mineral density of the periodontal bone with no pathology. With the techniques employed, modifications consistent with the bisphosphonates’ antiosteoclastic effect were observed.The accumulated evidence proved contradictory: on the one hand, a series of indicators (number and amplitude of resorption focuses, and bone loss evidenced by the increase of the LAC-COA distance and the histological images of bone resorption) would suggest that the “spontaneous” periodontal illness advances with age. However, the lymphocyte clusters in the periodontal tissue were observed only in the 4th week. These results suggest two hypotheses:The “spontaneous” periodontal illness is an example of immune tolerance.The modifications observed in very young rats’ periodontium are produced by the environmental antigens in an immaturity period of the immune system.Received: Jul. 2008 | Accepted: Sep. 2008La enfermedad periodontal es una respuesta inflamatoria del tejido periodontal a las bacterias contenidas en la placa bacteriana con destrucción de fibras colágenas, migración apical del epitelio de unión y pérdida del hueso alveolar. El daño producido puede conducir a la pérdida dental.Con el fin de evaluar el crecimiento mandibular y describir el desarrollo de la enfermedad periodontal “espontánea” de la rata se utilizaron animales controles línea “m” y se corrobororaron los hallazgos observados con dos modelos experimentales (diabetes experimental y bisfosfonatos). El modelo de diabetes experimental fue explorado dado que se considera a la diabetes como factor agravante de la enfermedad periodontal. Se efectuó un ensayo terapéutico con bisfosfonatos, drogas de reconocido efecto antiosteoclástico, ya que la enfermedad periodontal puede considerarse una enfermedad del metabolismo óseo por la característica reabsorción de hueso.El crecimiento mandibular de las ratas controles fue armónico con el corporal. La diabetes tuvo un efecto adverso sobre el crecimiento corporal que no se manifestó en el peso seco, densidad ni volumen de la mandíbula. En los animales tratados con Lidadronato se encontró un aumento significativo en el peso seco y volumen mandibular respecto de los controles. Estos resultados son congruentes con el conocido efecto antireabsortivo de estas drogas.La técnica de densitometría ósea radiológica permitió la evaluación simultánea de los tres principales componentes de la estructura ósea: el grosor de la cortical, su porosidad y el grado de mineralización del hueso. La medición de la distancia desde la línea amelocementaria a la cresta ósea alveolar (LAC-COA) resultó un excelente método morfométrico. Esta distancia aumentó con el paso del tiempo y fue mayor en la cara lingual que en la vestibular, tanto en animales controles, diabéticos como tratados con bisfosfonatos. La medición del hueso periodontal de soporte (HPS) no ha demostrado ser un recurso útil para evaluar el curso de la enfermedad periodontal durante el período de rápido crecimiento de la rata ya que se combinan la erupción activa, la erupción pasiva y la enfermedad periodontal. Este método resultaría útil después que el animal haya completado su crecimiento.La enfermedad periodontal apareció luego del destete y se desarrolló hacia la 6ª o 7ª semana de vida sin evidencias de alteraciones patológicas del tejido gingival.En los animales diabéticos se observó un mayor número de focos de reabsorción con menor área total en reabsorción involucrada. La disminución del turnover óseo y la probable tolerancia inmunológica a los gérmenes habituales en el alimento y la boca explicarían esta observación. La densidad mineral del hueso periodontal sin patología fue, en promedio, 34% menor comparándolos con los controles. La densidad mineral del hueso periodontal en reabsorción también fue significativamente menor. Dosis iguales de dos bisfosfonatos no produjeron los mismos resultados. El Lidadronato redujo el área total en reabsorción. El Olpadronato aumentó significativamente la densidad mineral del hueso periodontal sin patología. Con las técnicas empleadas se observan modificaciones congruentes con el efecto antiosteoclástico de los bisfosfonatos. La evidencia acumulada fue contradictoria: por una parte, una serie de indicadores (número y amplitud de focos de reabsorción y la pérdida ósea puesta en evidencia por el aumento de la distancia entre la línea amelocementaria y la cresta ósea alveolar y las imágenes histológicas de reabsorción ósea) indicarían que la enfermedad periodontal “espontánea” progresa con el avance de la edad. Sin embargo, sólo a la 4ª. semana se observaron los acúmulos de linfocitos en el tejido periodontal. Estos resultados sugieren dos hipótesis:La Enfermedad Periodontal “Espontánea” es un ejemplo de tolerancia inmunológicaLas modificaciones observadas en el periodonto de ratas muy jóvenes son producto de los antígenos ambientales en un período de inmadurez del sistema inmune.Recibido: Jul. 2008 | Aceptado: Sep. 2008Para citar este artículo:García, María. Estudio de la dinámica ósea mandibular y de los procesos reabsortivos de la cresta alveolar en ratas diabéticas y controles. e-Universitas UNR Journal [Online], Volumen 1 Número 1. [noviembre 2008]. Disponible en: http://www.e-universitas.edu.ar/journal/index.php/journal/article/view/13. ISSN 1666-6143. AbstractPeriodontal illness is an inflammatory reaction of the periodontal tissue to the bacteria in the dental plaque.In order to assess the mandibular growth and describe the development of rats’ “spontaneous” periodontal illness, control animals line “m” were employed. The findings observed were corroborated against two experimental models (experimental diabetes and bisphosphonates). The experimental diabetes model was explored, because diabetes is considered an aggravating factor of periodontal illness. A therapeutic assay was carried out with bisphosphonates, which are highly recognized drugs for their antiosteoclastic effect. Periodontal illness can be considered an illness of the bone metabolism, given the typical bone resorption.In control rats, mandible growth matched body growth. Diabetes had an adverse effect on body growth which did not show in dry weight, density or mandible volume. In comparison with the control animals, animals treated with lidadronate (IG-9402) revealed a significant increase in dry weight and mandible volume. These results are consistent with such drugs’ well-known antiresorptive effect.The distance between the amelo-cementum junction and the alveolar bone crest (LAC-COA) increased as time elapsed, and it was bigger on the lingual side than on the vestibular side, in control animals, in diabetic animals and in animals treated with bisphosphonates. Measurement of the supporting periodontal bone (HPS) has not proved to be a useful means to assess periodontal illness during the rat’s fast-growing period.Periodontal illness appeared after weaning, and developed towards the 6th or 7th week after birth, with no signs of pathological alteration of the gingival tissue.In diabetic animals, there was a bigger number of focuses with lower total area in the resorption involved. Lower bone turnover, as well as the likely immunological tolerance to the usual food and mouth germs, account for this observation. The mineral density of the periodontal bone with no pathology was, on average, 34% lower in comparison with the control animals. The mineral density of the periodontal bone in resorption was also significantly lower.Equal doses of two bisphosphonates did not produce equal results. Lidadronate reduced the total area in resorption. Olpadronate significantly increased the mineral density of the periodontal bone with no pathology. With the techniques employed, modifications consistent with the bisphosphonates’ antiosteoclastic effect were observed.The accumulated evidence proved contradictory: on the one hand, a series of indicators (number and amplitude of resorption focuses, and bone loss evidenced by the increase of the LAC-COA distance and the histological images of bone resorption) would suggest that the “spontaneous” periodontal illness advances with age. However, the lymphocyte clusters in the periodontal tissue were observed only in the 4th week. These results suggest two hypotheses:The “spontaneous” periodontal illness is an example of immune tolerance.The modifications observed in very young rats’ periodontium are produced by the environmental antigens in an immaturity period of the immune system.Received: Jul. 2008 | Accepted: Sep. 2008To cite this article:García, María. Study of the mandibular bone dynamics and of the alveolar crest resorption processes in diabetic and control rats. e-Universitas UNR Journal [Online], Volumen 1 Número 1. [noviembre 2008]. Available in: http://www.e-universitas.edu.ar/journal/index.php/journal/article/view/13. ISSN 1666-6143.Artigo não disponível em português