Modelo de expansión de la sutura media palatina, inducido por fuerzas mecánicas, en ratas / Model of disjunction of the median palatine suture in rats

El objetivo del presente estudio fue desarrollar unmodelo de disyunción de la sutura media palatina enratas Wistar, mediante una técnica sencilla, fácilmentereproducible y de bajo costo.Se utilizaron 16 ratas hembras Wistar jóvenes, de pesosimilar, anestesiadas con clorhidrato de ketamina(14 mg/kg) y acepromacina (10 mg/kg) vía intraperitoneal...

The aim of this study was to develop a model ofdisjunction of the median palatine suture in Wistarrats, by a simple, easily reproducible and inexpensivetechnique.Sixteen young female Wistar rats of similar weightanesthetized with ketamine hydrochloride (14 mg/kg)and acepromazine (10 mg/kg) via intraperitonealroute were used...

Respuesta del tejido periapical de la rata a la sobreobturaci¨®n intencional de conos de resilon y conos de gutapercha recubiertos con resina / Periapical tissue response to intentional overextension of resilon and resin-coated gutta-percha cones: a preliminary study in rats

Objetivos. La sobreobturaci¨®n accidental o inadvertida con conos de gutapercha ocurre con cierta frecuencia en endodoncia cl¨ªnica. El prop¨®sito deeste estudio fue analizar la respuesta de los tejidos periapicales de la rata a sobreobturaciones intencionalesde conos de Resilon o conos de gutapercha recubiertos con resina. Material y m¨¦todos. Se obtuvo el acceso al conducto distal de los primeros molares inferiores (izquierdoy derecho) de 16 ratas macho Wistar con un peso de ¡À 250 g. Los conductos fueron preparados y sobreobturados con los materiales problema hasta una medida estandarizada de ¡À1 mm m¨¢s all¨¢ del ¨¢pice mediante el empleo de un localizador apical electr¨®nico. Las mand¨ªbulas fueron disecadas, fijadas en formol-buffer al 10 por ciento y descalcificadas. Los molares y los tejidos circundantes se prepararonpara su estudio histol¨®gico de rutina y se obtuvieron cortes seriados de aproximadamente 7 ¦Ìm de espesor de la ra¨ªz distal, los que fueron coloreadoscon hematoxilina y eosina. Los datos se categorizaron de acuerdo con par¨¢metros previamente establecidos y se analizaron mediante los tests deFisher, Kruskal-Wallis y el de comparaci¨®n m¨²ltiple de Dunn.Resultados. Luego de 30 d¨ªas la reacci¨®n a los materiales problema demostraron una respuesta inflamatoria moderada a severa. Estas reacciones disminuyeron significativamente (p<0.05) a los 90d¨ªas. En este lapso se observ¨® una reparaci¨®n progresiva de los tejidos periapicales circundada por un activo desarrollo de nuevas trab¨¦culas ¨®seas deapariencia normal. Conclusiones. Al finalizar la experiencia la reacci¨®n fue similar para ambos materiales, los que fueron bien tolerados por los tejidos periapicales, sin interferir con el proceso reparativo.

Respuesta del tejido periapical de la rata a la sobreobturaci¿«n intencional de conos de resilon y conos de gutapercha recubiertos con resina / Periapical tissue response to intentional overextension of resilon and resin-coated gutta-percha cones: a preliminary study in rats

Objetivos. La sobreobturaci¿«n accidental o inadvertida con conos de gutapercha ocurre con cierta frecuencia en endodoncia cl¿¬nica. El prop¿«sito deeste estudio fue analizar la respuesta de los tejidos periapicales de la rata a sobreobturaciones intencionalesde conos de Resilon o conos de gutapercha recubiertos con resina. Material y m¿ªtodos. Se obtuvo el acceso al conducto distal de los primeros molares inferiores (izquierdoy derecho) de 16 ratas macho Wistar con un peso de í? 250 g. Los conductos fueron preparados y sobreobturados con los materiales problema hasta una medida estandarizada de í?1 mm m¿ós all¿ó del ¿ópice mediante el empleo de un localizador apical electr¿«nico. Las mand¿¬bulas fueron disecadas, fijadas en formol-buffer al 10 por ciento y descalcificadas. Los molares y los tejidos circundantes se prepararonpara su estudio histol¿«gico de rutina y se obtuvieron cortes seriados de aproximadamente 7 ªÌm de espesor de la ra¿¬z distal, los que fueron coloreadoscon hematoxilina y eosina. Los datos se categorizaron de acuerdo con par¿ómetros previamente establecidos y se analizaron mediante los tests deFisher, Kruskal-Wallis y el de comparaci¿«n m¿²ltiple de Dunn.Resultados. Luego de 30 d¿¬as la reacci¿«n a los materiales problema demostraron una respuesta inflamatoria moderada a severa. Estas reacciones disminuyeron significativamente (p<0.05) a los 90d¿¬as. En este lapso se observ¿« una reparaci¿«n progresiva de los tejidos periapicales circundada por un activo desarrollo de nuevas trab¿ªculas ¿«seas deapariencia normal. Conclusiones. Al finalizar la experiencia la reacci¿«n fue similar para ambos materiales, los que fueron bien tolerados por los tejidos periapicales, sin interferir con el proceso reparativo.(AU)

Subcutaneous connective tissue reaction to methacrylate resin-based and zinc oxide and eugenol sealers.

INTRODUCTION: An evaluation was made of the connective tissue reaction in rats after subcutaneous implantation of methacrylate resin-based sealers (EndoREZ [Ultradent Products, Inc, South Jordan, UT] with a polymerization accelerator and RealSeal [Sybron Dental Specialties, Orange, CA]) and Pulp Canal Sealer (Sybron Dental Specialties), a zinc oxide and eugenol-based sealer used as the control. METHODS: Silicone tubes containing the test materials were implanted in 24 Wistar rats. Solid silicone rods of the same size served as the negative controls. After 10, 30, and 90 days, the animals (n = 8 per period) were euthanized and the implants with surrounding tissues dissected and processed for routine histological evaluation. A four-category evaluation system was used to measure and record the microscopic observations according to the thickness of a fibrous capsule, the vascular changes, and the various types of inflammatory cells. RESULTS: Initially, a severe inflammatory reaction was observed of the soft tissues in direct contact with both EndoREZ/Accelerator and Real Seal. The severity decreased over time and was resolved at the end of the experiment. Pulp Canal Sealer showed a severe tissue reaction for all observation periods. The negative controls showed an initial mild to moderate inflammatory reaction. After 30 days, healthy fibrous connective tissue was observed, which increased over time. After 10 days, no statistically significant differences between the experimental groups were observed. After 90 days, EndoREZ and RealSeal were statistically significantly less toxic than Pulp Canal Sealer (p > 0.05). CONCLUSIONS: After 90 days, both methacrylate resin-based sealers were considered biologically acceptable when implanted in subcutaneous connective tissues of the rat. Pulp Canal Sealer remained toxic for the duration of the study.

Rat subcutaneous tissue response to modified Portland cement, a new mineral trioxide aggregate.

The purpose of this study was compare the biocompatibility of modified Portland cement (CPM) and mineral trioxide aggregate (MTA) in a subcutaneous rat model. Twenty-four male Wistar rats were used. Three silicon tubes were placed on the dorsal subcutaneous tissue of each animal: one tube contained MTA, one tube contained CPM and the other was an empty tube. The rats were sacrificed in 3 groups of 8 animals at 7, 14 and 30 postoperative days, respectively. Tissue samples were fixed in 10% buffered formalin, embedded in paraffin, and serial sections were cut and stained with hematoxylin and eosin, Masson Trichrome and Luna's stain. At day 7, the empty tubes displayed a mild inflammatory infiltrate. In the CPM group, an inflammatory infiltrate was observed with some eosinophils and immature connective tissue. The MTA group showed a similar infiltrate without eosinophils and presence of abundant necrotic tissue and numerous multinucleate foreign body giant cells. At day 14, the chronic infiltrate with eosinophils persisted when in contact with CPM. In the MTA group, necrosis and distant giant cells could still be seen. At day 30, all 3 groups showed mature fibrous collagenous tissue. These findings indicate a different response to the materials evaluated in this study. Although, MTA and CPM induced a chronic inflammatory infiltrate, necrosis and multinucleated foreign body giant cells predominated in the MTA group, while in the CPM group numerous eosinophils were seen at all the observational periods.

Rat subcutaneous tissue response to modified Portland Cement, a new mineral trioxide aggregate

The purpose of this study was compare the biocompatibility of modified Portland cement (CPM) and mineral trioxide aggregate (MTA) in a subcutaneous rat model. Twenty-four male Wistar rats were used. Three silicon tubes were placed on the dorsal subcutaneous tissue of each animal: one tube contained MTA, one tube contained CPM and the other was an empty tube. The rats were sacrificed in 3 groups of 8 animals at 7, 14 and 30 postoperative days, respectively. Tissue samples were fixed in 10 percent buffered formalin, embedded in paraffin, and serial sections were cut and stained with hematoxylin and eosin, Masson Trichrome and Luna's stain. At day 7, the empty tubes displayed a mild inflammatory infiltrate. In the CPM group, an inflammatory infiltrate was observed with some eosinophils and immature connective tissue. The MTA group showed a similar infiltrate without eosinophils and presence of abundant necrotic tissue and numerous multinucleate foreign body giant cells. At day 14, the chronic infiltrate with eosinophils persisted when in contact with CPM. In the MTA group, necrosis and distant giant cells could still be seen. At day 30, all 3 groups showed mature fibrous collagenous tissue. These findings indicate a different response to the materials evaluated in this study. Although, MTA and CPM induced a chronic inflammatory infiltrate, necrosis and multinucleated foreign body giant cells predominated in the MTA group, while in the CPM group numerous eosinophils were seen at all the observational periods.

O propósito deste estudo foi comparar a biocompatibilidade do cimento Portland modificado (CPM) com agregado de trióxido mineral (MTA) no subcutâneo de um modelo murino. Foram usados 24 ratos Wistar macho. No tecido subcutâneo dorsal de cada animal se colocaram 3 tubos de silicone. Um contendo MTA, outro CPM e o último vazio. Os animais foram sacrificados em 3 grupos de 8 aos 7, 14 e 30 dias. As amostras se fixaram em formol e se coloriram com hematoxilina - eosina, Masson e Luna. No dia 7 os tubos vazios mostraram uma leve infiltração de células inflamatórias. No grupo CPM, se observou um infiltrado inflamatório com alguns eosinófilos e tecido conectivo imaturo. O grupo MTA mostrou um infiltrado similar sem eosinófilos e abundante necrose de tecido e numerosas células gigantes multinucleadas do tipo corpo estranho. Ao dia 14, o infiltrado crônico com eosinófilos persistiu em contato com CPM. No grupo MTA, a necrose e células multinucleadas afastadas ainda se podiam observar. Ao dia 30, os 3 grupos mostraram tecido fibroso maduro. Estes resultados mostram uma resposta diferente aos materiais avaliados no presente estudo. Apesar do que MTA e CPM causaram um infiltrado crônico, no grupo MTA predominou a necrose e as células gigantes, enquanto isso, no grupo CPM se observaram grandes quantidades de eosinófilos.

Pulsed electromagnetic fields as adjuvant therapy in bone healing and peri-implant bone formation: an experimental study in rats.

The objective of this study was to determine whether short exposure to pulsed electromagnetic fields (PEMF) accelerates bone repair and peri-implant bone formation in a rat tibial model at different times. Sixty Wistar rats were employed. Sterile custom fabricated commercially pure cylinder threaded titanium implants were placed in the right tibial crest, and an osteotomy was performed in the left tibial crest of each animal. Thirty rats were treated with PEMF (72 mT 50Hz), twice a day in sessions of 30 minutes each, and 30 rats of the control group were sham-treated. Rats were sacrificed at 5, 10 and 20 days postsurgery (n = 10 per group). Tibias were fixed in formaldehyde and decalcified, embedded in paraffin, and stained with hematoxylin-eosin (half samples of left tibias), or they were included in methylmethacrylate, grinded and polished (right tibias and half samples of left tibias). Bone healing was evaluated by image analysis in terms of ossification area, and perimeter and diameter of the lesion. Peri-implant ossification was assessed in terms of ossification percentage. At day 10 the area of ossification index was higher in the PEMF group than in the control group (p = 0.012). At day 20 the osteotomies of the PEMF group were almost completely remodeled. The ossification percentage was higher in the PEMF group (p = 0.018). In conclusion, short daily electromagnetic stimulation appears to be a promising treatment for acceleration of both bone-healing and peri-implant bone formation.

¿Es el plasma rico en plaquetas (PRP) promotor de la cicatrización ósea en ratas diabéticas? / Effect of platelet rich plasma in diabetic rats

La ocurrencia de osteoporosis está documentada en diabetes tipo I. el objetivo de este trabajo fue evaluar el efecto del plasma rico en plaquetas (PRP) sobre la cicatrización ósea en ratas diabéticas... Como resultado el grupo control mostró ± 7,76 por ciento vs. 63,12 ± 15,34 porciento del grupo experimental de hueso neoformado (p= 0,0317). Como conclusión estos resultados sugieren un efecto favorecedor del PRP en la cicatrización ósea diabética, y potencialmente en otras fracturas de alto riesgo.

Caracterización ósea en modelo Murino de diabetes tipo 1 / Bone characterization in diabetes type 1 in a Murine model

Si bien la ocurrencia de osteoporosis está documentada en diabetes tipo 1, el objetivo de este trabajo es caracterizar ciertos cambios morfológicos, morfométricos y biomecánicos en huesos largos de un modelo de esta patología

Caracterización ósea en modelo Murino de diabetes tipo 1 / Bone characterization in diabetes type 1 in a Murine model

Si bien la ocurrencia de osteoporosis está documentada en diabetes tipo 1, el objetivo de este trabajo es caracterizar ciertos cambios morfológicos, morfométricos y biomecánicos en huesos largos de un modelo de esta patología(AU)