Study of epithelial rests of Malassez in an experimental periodontitis model.

The aim of this study was to evaluate the morphological alterations of epithelial cell rests of Malassez (ERMs) and their relationship with root resorption, in an experimental periodontitis (EP) model at 4 and 11 days. EP was induced in 14 male Wistar rats by placing a cotton thread ligature around the neck of the first lower right molar, for 4 (n=7) and 11 (n=7) days. The contralateral molar (left) was used as control. Following euthanasia, jaws were extracted and processed histologically to provide mesio-distal sections which were subject to H&E stain and histochemical detection technique with tartrate-resistant acid phosphatase (TRAP). The following histomorphometricparameters were evaluated on micrographs: bone area (BAr./TAr)(%), number of ERMs/mm2, number of cells/ERM, ERMs area (µm2), and percentage of root resorption surfaces (%RR). The results were analyzed statistically by ANOVA and Bonferronipost hoc (p≤ 0.05). Significant bone loss was observed in molars with EP compared to their controls. In the EP 4-Day group, no change was observed in the parameters with relation to the ERMs; however, in the EP 11-Day group, there was significant root resorption (%RR) (C: 3.21±3.07, EP-4D: 3.91±3.17, EP-11D: 23.67± 11.40; p≤ 0,05) and increase in ERMs area (µm2) (C: 455.87±145.42, EP-4D: 577.6±156.1, EP-11D: 1046.3± 582.9; p≤ 0,05). No TRAP+ ERM was found in either group. ERM hypertrophy may be related to ERMpartici-pation in mechanisms tending to establish periodontal homeostasis, inhibiting resorption and contributing toperiodon-tal regeneration.

El objetivo de este trabajo ha sido evaluar las alteraciones morfológicas de epithelial cell rests of Malassez (ERMs) y su relación con la reabsorción radicular, en un modelo de experimental periodontitis (EP) a 4 y 11 días. La EP fue inducida en 14 ratas Wistar macho mediante la colocación de una ligadura de hilo de algodón alrededor del cuello del primer molar inferior derecho, a 4 (n=7) y 11 (n=7) días. El molar contralateral (izquierdo) fue usado como control. Tras la eutanasia, se extrajeron los maxilares y se procesaron histológicamente para la obtención de cortes en sentido mesio-distal que se colorearon con H&E y técnica histoquímica de detección de tartrate-resistant acid phosphatase (TRAP). Se tomaron microfotografías y se evaluaron los siguientes parámetros histomorfométricos: Bone area (BAr./TAr)(%), N° de ERMs/mm2, N° de células/ERM, área de ERMs (µm2), y porcentaje de superficies de reabsorción radicular (%RR). Los resultados se analizaron estadísticamente mediante Anova y Bonferroni post hoc (p≤ 0.05). En los molares con PE se observó una pérdida ósea significativa en relación a sus controles. En el grupo EP 4 días no se observaron cambios en los parámetros en relación a los ERMs, sin embargo, en el grupo PE de 11 días se registró reabsorción radicular (%RR) significativa (C: 3.21±3.07, EP-4D: 3.91±3.17, EP-11D: 23.67±11.40; p≤ 0,05) junto con un aumento del área de ERMs (µm2) (C: 455.87±145.42, EP-4D: 577.6±156.1, EP-11D: 1046.3±582.9; p≤ 0,05). No se observaron ERMs TRAP+ en ninguno de los dos grupos. La hipertrofia de los ERMs, podría estar relacionada a la participación de los mismos en mecanismos tendientes a la homeostasis periodontal, inhibiendo dicha reabsorción y contribuyendo a la regeneración periodontal.

Study of epithelial rests of Malassez in an experimenal periodontitis model

The aim of this study was to evaluate the morphological alterations of epithelial cell rests of Malassez (ERMs) and their rela tionship with root resorption, in an experimental periodon titis (EP) model at 4 and 11 days. EP was induced in 14 male Wistar rats by placing a cotton thread ligature around the neck of the first lower right molar, for 4 (n=7) and 11 (n=7) days. The contralateral molar (left) was used as control. Following euthanasia, jaws were extracted and processed histologically to provide mesiodistal sections which were subject to H&E stain and histochemical detection technique with tartrateresistant acid phosphatase (TRAP). The following histomorphometric parameters were evaluated on micrographs: bone area (BAr./TAr)(%), number of ERMs/mm2, number of cells/ ERM, ERMs area (µm2), and percentage of root resorption surfaces (%RR). The results were analyzed statistically by ANOVA and Bonferroni post hoc (p£ 0.05). Significant bone loss was observed in molars with EP compared to their controls. In the EP 4Day group, no change was observed in the parameters with relation to the ERMs; however, in the EP 11Day group, there was significant root resorption (%RR) (C: 3.21±3.07, EP4D: 3.91±3.17, EP11D: 23.67± 11.40; p£ 0,05) and increase in ERMs area (µm2) (C: 455.87±145.42, EP4D: 577.6±156.1, EP11D: 1046.3± 582.9; p£ 0,05). No TRAP+ ERM was found in either group. ERM hypertrophy may be related to ERM partici pation in mechanisms tending to establish periodontal homeostasis inhibiting resorption and contributing to periodon tal regeneration (AU)

El objetivo de este trabajo ha sido evaluar las alteraciones morfológicas de epithelial cell rests of Malassez (ERMs) y su relación con la reabsorción radicular, en un modelo de experimental periodontitis (EP) a 4 y 11 días. La EP fue inducida en 14 ratas Wistar macho mediante la colocación de una ligadura de hilo de algodón alrededor del cuello del primer molar inferior derecho, a 4 (n=7) y 11 (n=7) días. El molar contralateral (izquierdo) fue usado como control. Tras la eutanasia, se extrajeron los maxilares y se procesaron histológicamente para la obtención de cortes en sentido mesiodistal que se colorearon con H&E y técnica histoquímica de detección de tartrateresistant acid phosphatase (TRAP). Se tomaron microfotografías y se evaluaron los siguientes parámetros histomorfométricos: Bone area (BAr./TAr)(%), Nº de ERMs/mm2, Nº de células/ERM, área de ERMs (µm2), y porcentaje de superficies de reabsorción radicular (%RR). Los resultados se analizaron estadísticamente mediante Anova y Bonferroni post hoc (p£ 0.05). En los molares con PE se observó una pérdida ósea significativa en relación a sus controles. En el grupo EP 4 días no se observaron cambios en los parámetros en relación a los ERMs, sin embargo, en el grupo PE de 11 días se registró reabsorción radicular (%RR) significativa (C: 3.21±3.07, EP4D: 3.91±3.17, EP11D: 23.67±11.40; p£ 0,05) junto con un aumento del área de ERMs (µm2) (C: 455.87±145.42, EP4D: 577.6±156.1, EP11D: 1046.3±582.9; p£ 0,05). No se observaron ERMs TRAP + en ninguno de los dos grupos. La hipertrofia de los ERMs, podría estar relacionada a la participación de los mismos en mecanismos tendientes a la homeostasis periodontal, inhibiendo dicha reabsorción y contribuyendo a la regeneración periodontal (AU)

Effect of topical administration of monosodium olpadronate on experimental periodontitis in rats.

BACKGROUND: Periodontitis is characterized by gingival inflammation, periodontal pocket formation, and bacterial plaque that lead to alveolar bone destruction. Research studies have recently begun to evaluate the effect of antiresorptive agents using experimental models of periodontitis. Bisphosphonates are the most frequently tested antiresorptive agents; their main effect is inhibition of bone resorption. The aim of this study was to perform a histomorphometric evaluation of the preventive effect of monosodium olpadronate (OPD), an aminobisphosphonate, on experimental periodontitis (EP). METHODS: Twenty male Wistar rats were used in this experiment. The animals were assigned to one of two groups: group I: EP; and group II: EP plus topical administration of OPD (EP + OPD). The contralateral side in both groups served as untreated controls (CI and CII), respectively. Mesio-distally oriented sections of each lower first molar were obtained for histomorphometric evaluation. RESULTS: The treated group (EP + OPD) exhibited marked inhibition of bone loss; interradicular bone volume was significantly greater than that observed in the EP group. The height of the periodontal ligament in the interradicular alveolar bone, which served as an indirect measure of bone loss, was found to be significantly increased in the EP group as compared to the EP + OPD group. Osteoclasts in the OPD treated group were detached from the bone surface, were round in shape, and exhibited a loss of polarity and lack of ruffled borders. CONCLUSIONS: The dose used herein was found to inhibit bone loss and to cause marked morphologic changes in osteoclasts. The drug effectively prevented bone loss caused by periodontitis.

Alterations of tooth eruption and growth in pups suckling from diabetic dams.

Several studies have confirmed a decrease in the quality and quantity of milk of mothers with diabetes during lactation. However, it remains unclear how maternal diabetes affects the offspring specifically during lactation. The aim of this study was to evaluate body and mandibular growth and tooth eruption in pups suckling from diabetic dams. The study was performed on 13 Wistar rat pups that were born to dams that were subjected to experimental diabetes on the day of parturition. Body weight and body size were recorded regularly throughout the study. The experimental pups and a group of eight age-matched pups suckling from nondiabetic dams were killed at weaning. Both hemimandibles were excised and fixed. Right hemimandibles were radiographed to assess mandibular growth and tooth eruption. The left hemimandibles were processed to obtain buccolingually oriented sections at the level of the first mesial root of the first lower molar. Histologic and histomorphometric studies were performed. Results showed that body weight and body size were significantly lower in experimental animals at weaning compared with their age-matched controls. Smaller mandible size and reduced tooth eruption in experimental animals compared with controls were observed. The length, width, and bone volume of the developing alveolus were reduced in experimental animals compared with controls. The results obtained in this study allow the conclusion that suckling from diabetic dams results in reduced body, mandible size, and tooth eruption of the pups at weaning.