Impact of infected and noninfected human dentine debris on bone healing in rats.

AIM: To evaluate in vivo the bone tissue response of rats to varying amounts of infected and noninfected dentine debris. METHODOLOGY: Bone tissue reactions were evaluated histologically in 42 Wistar rats after 7, 30 and 60 days. For each animal, three surgical cavities were prepared on the femur and filled with varying amounts (5, 10 or 20 mg) of infected or noninfected dentine debris pellets. In the negative control group, the surgical cavities were not filled. At the end of each experimental period, the animals were euthanized. The samples were processed histologically and analysed using a light microscope. The presence and the severity of inflammatory reaction, as well as hard tissue deposition were evaluated. Data were subjected to statistical analysis and the effects of the dependent variables calculated using nonparametric tests Kruskal-Wallis and Mann-Whitney U with due Bonferroni corrections at P = 0.05. RESULTS: At 7 days, the presence of infected debris significantly increased the histopathological scores for neutrophils (P < 0.05), and abscess formation (P < 0.05). Noninfected debris scored significantly higher for lymphocyte infiltrate compared with the control group and infected debris (P < 0.05). Both infected and noninfected debris equally triggered eosinophil cells compared with no-dentine (P < 0.05). As for giant cells and macrophages, no difference was detected amongst the dentine groups (P > 0.05). Hard tissue deposition was similar regardless of the presence or the bacteriological status of the dentine (P = 1.00). None of the above histopathological parameters was significantly influenced by the amount of debris (P > 0.05). For all parameters evaluated, at 7 days of analysis, the inflammatory response was significantly more intense compared with 30 and 60 days (P < 0.05). Inflammatory parameters were scored similarly for the evaluated groups after 30 and 60 days (P > 0.05). However, hard tissue deposition has significantly increased after 30 days (P < 0.05). No difference was seen between 30 and 60 days of analysis (P = 1.00) for all histological parameters evaluated. CONCLUSION: The assumption that the amount of extruded debris may negatively affect the inflammatory response of bone tissue was not validated in the present in vivo animal study. Infected dentine may trigger acute inflammatory parameters especially during the first 7 days of contact with the tissue; however, in the long term, these negative effects are mitigated.

Endodontic re-instrumentation enhances hydroxyl ion diffusion through radicular dentine.

AIM: To evaluate the diffusion of hydroxyl ions from calcium hydroxide paste (CH) before root canal filling and after retreatment. METHODOLOGY: After preparation of 60 root canals, the cementum layer was removed, and the canals and root surfaces were treated for smear layer removal. The apical third of roots was covered with adhesive. The canals were filled with CH, and the teeth were placed in individual vials containing 10 mL of distilled water, which had its pH measured after 7, 14, 21 and 28 days (pH1). The root canals were then divided into five groups and filled with Resilon/Real Seal (G1) or gutta-percha and Endofill (G2), Sealapex (G3), AH Plus (G4) or MTA Fillapex (G5) sealers. After storage for 7 days, the root canals were retreated. The CH was again inserted into the canals, and the teeth were placed in new vials containing 10 mL of distilled water. The pH was again measured at 7, 14, 21 and 28 days (pH2). The initial and final pH readings (pH1 and pH2) were compared by anova, anova2 and Tukey's tests (P < 0.05). RESULTS: The pH1 and pH2 measurements increased with time. The measurements obtained after retreatment were significantly higher than those obtained before root canal filling. CONCLUSIONS: Hydroxyl ions are able to diffuse through dentinal tubules. Regardless of the filling material, it was possible to re-establish the permeability of dentine to ionic diffusion after retreatment. Time had a positive influence on ionic diffusion.

Pinealectomia em ratas Wistar (Rattus norvegicus albinus): descrição de um novo método cirúrgico / Pinealectomy in Wistar rats (Rattus norvegicus albinus): Description of a new surgical method

A necessidade de manejo adequado antes, durante e após a implementação de procedimentos em animais de laboratório é essencial para proporcionar bem-estar. Portanto, no presente trabalho, objetivou-se padronizar uma nova técnica de pinealectomia em ratas Wistar. Trinta fêmeas nulíparas aos 90 dias de idade foram submetidas à anestesia dissociativa. Após a tricotomia e a assepsia, realizou-se uma incisão na linha média dorsal da cabeça. Com um micromotor e uma broca de aço PM 03, realizou-se a craniotomia; a glândula pineal foi removida por intermédio de um fórceps cápsula arruga. Em seguida, o fragmento ósseo foi recolocado em seu lugar de origem, e a pele aproximada por pontos simples. Finalizado o procedimento cirúrgico, foi realizada antibioticoterapia e soroterapia parenteral. O acompanhamento diário dos animais não evidenciou nenhum comprometimento da ferida operatória com padrão de cicatrização por primeira intenção. Os animais apresentaram normalidade de atos fisiológicos, como alimentação, defecação e micção, assim como socialização com o grupo. Técnicas cirúrgicas vêm sendo realizadas com o desenvolvimento das pesquisas envolvendo a glândula pineal. A técnica ideal para pinealectomia consiste no pouco sangramento, na curta duração da cirurgia e na nitidez da glândula pineal, diminuindo a probabilidade de acidentes neurológicos. Considerando-se os resultados obtidos ao longo do desenvolvimento experimental e clínico, o aprimoramento da técnica cirúrgica utilizando a broca PM03 associada ao fórceps cápsula arruga foi exímio na pesquisa científica da pinealectomia de ratas Wistar em virtude da rapidez e praticidade alcançadas. Tem-se a perspectiva de que este artigo sirva de subsídio para o aprimoramento e a otimização do modelo experimental para posteriores estudos acerca de pesquisas com a glândula pineal e, assim, maior compreensão de sua complexidade sobre todos os sistemas do organismo.

The need for adequate management before, during and after procedures involving laboratory animals is essential to their wellbeing. Thus, the aim of the present study was to standardize a novel method of pinealectomy in Wistar rats. Thirty nullipara females aged 90 days were submitted to dissociative anesthesia. Following fur removal and asepsis, an incision was performed along the dorsal line of the head. Craniotomy was performed with a mini-drill and PM 03 stainless steel drill bit. The pineal gland was removed using a serrated capsule forceps. The bone fragment was replaced and the skin was sutured with simple stitches. The surgical procedure was finalized with antibiotic therapy parenteral serotherapy. Daily follow up was performed and no animal demonstrated any compromised surgical wound with first intention wound healing. The animals exhibited normal physiological acts (feeding, defecation, urination and group socialization). Surgical techniques were performed with the development of research involving the pineal gland. The ideal pinealectomy method consists of little bleeding, a short surgery and a clear view of the pineal gland, thereby diminishing the probability of neurological accidents. Considering the results obtained through the experimental and clinical development, the perfection of the surgical technique involving the PM03 drill bit and serrated capsule forceps was successful in scientific research involving pinealectomy of Wistar rats in terms of quickness and practicality. This article can assist in the optimization of experimental models for subsequent studies involving the pineal gland and the understanding of its complexity over all organism systems.