RESUMO
OBJECTIVE: To describe the ultrastructure of the interface between periodontal tissues and titanium mini-implants in rat mandibles. MATERIALS AND METHODS: A titanium mini-implant was placed between the buccal roots of the mandibular first molar of 24 adult rats. After 21, 30, 45, 60, 90, and 120 days of implantation, the mandibular portion was removed and fixed in cacodylate-buffered 2% glutaraldehyde + 2.5% formaldehyde. The material was decalcified and processed for scanning and transmission electron microscopy. RESULTS: Ultrastructural analysis revealed a thin cementum-like layer at longer times after implantation at the areas in which the periodontal ligament was in contact with the implant. CONCLUSIONS: The alveolar bone and the periodontal ligament reorganized their constituents around the implant, and a thin cementum-like layer was formed at longer times after implantation at the areas in which the periodontal ligament was in contact with the implant.
Assuntos
Implantes Dentários , Materiais Dentários , Mandíbula/cirurgia , Ligamento Periodontal/ultraestrutura , Titânio , Processo Alveolar/ultraestrutura , Animais , Colágeno/ultraestrutura , Cemento Dentário/ultraestrutura , Materiais Dentários/química , Masculino , Mandíbula/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Dente Molar/anatomia & histologia , Procedimentos de Ancoragem Ortodôntica/instrumentação , Osseointegração/fisiologia , Osteoblastos/ultraestrutura , Osteócitos/ultraestrutura , Osteogênese/fisiologia , Ratos , Ratos Wistar , Propriedades de Superfície , Fatores de Tempo , Titânio/química , Raiz Dentária/anatomia & histologiaRESUMO
This study evaluated, by SEM, the morphology of human primary teeth roots. Twenty-four teeth were divided into 3 groups: pulp vitality (group I) and pulp necrosis without (group II) and with apical periodontitis (group III). Roots were analyzed by the presence of periodontal ligament (PDL) fibers and resorption areas. In groups I and II, presence of PDL fibers and absence of resorption were observed in all cases (100%), while all specimens (100%) of group III showed no PDL fibers and resorption areas. In conclusion, there are morphological differences in the apical region of primary teeth with different pulpal and periapical pathologies.
Assuntos
Polpa Dentária/ultraestrutura , Microscopia Eletrônica de Varredura/métodos , Raiz Dentária/ultraestrutura , Dente Decíduo/ultraestrutura , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Necrose , Ligamento Periodontal/ultraestruturaRESUMO
The rat model is widely used in periodontal research and the quality of histological sections is essential. The purpose of this study was to evaluate the histological characteristics of periodontal tissues in Wistar rat maxillae, with different times of fixation and decalcified by nitric acid or formic acid (Anna Morse Solution). Fifteen rats were used. Fixation was performed for 24, 48 and 72 hours. The maxillae were hemi-sectioned and each part was decalcified either in nitric acid for 7 days or in Anna Morse solution for 35 days. Two trained and blinded examiners performed the evaluation. Fourty eight hours of fixation and decalcification with Anna Morse solution showed more clear characteristics of the epithelium-connective tissue interface and of the periodontal structures. Mean measurements between the cementum-enamel junction and the bone crest varied in the different experimental times from 176.5 (+/- 60.45) to 210.94 (+/- 39.33) pixels on the buccal aspect, and from 199.69 (+/- 38.33) to 298.55 (+/-70.81) pixels on the palatal aspect, with no statistically significant differences (ANOVA, p > 0.05). In the same fixation period, decalcification with nitric acid or Anna Morse solution did not display any statistically significant differences. It may be concluded that for a qualitative histological analysis, fixation should preferably be for 48 hours and the demineralization should be made by Anna Morse solution. For a histomorphometric analysis, the decalcification solution does not interfere in the results.
Assuntos
Formiatos/farmacologia , Ácido Nítrico/farmacologia , Doenças Periodontais/patologia , Ligamento Periodontal/patologia , Periodonto/patologia , Fixação de Tecidos/métodos , Análise de Variância , Animais , Técnica de Descalcificação , Modelos Animais de Doenças , Masculino , Maxila , Microscopia Eletrônica , Ligamento Periodontal/ultraestrutura , Periodonto/diagnóstico por imagem , Periodonto/efeitos dos fármacos , Ratos , Ratos Wistar , Estatísticas não Paramétricas , Fatores de Tempo , UltrassonografiaRESUMO
Destruction of dental tissue and supporting structures is usually microscopically assessed by routine hematoxylin and eosin (HE)-stained sections. This short communication is concerned with the potential role of fluorescence microscopy of HE-stained sections to study morphological aspects of intact and pathological teeth in dental research. This methodology improves the visualization of the anatomical structures of the intact teeth, especially anatomical features and periodontal ligament spatial distribution. This technique also improves the visualization of the root and bone resorption and the delineation of the periapical lesion extension. The fluorescence microscopy technique of HE-stained sections is an easy, reliable and inexpensive method that seems to be a useful tool for evaluating morphological aspects of intact and pathological teeth in dental research.
Assuntos
Microscopia de Fluorescência/métodos , Ligamento Periodontal/ultraestrutura , Dente/ultraestrutura , Corantes/química , Amarelo de Eosina-(YS)/química , Corantes Fluorescentes/química , Hematoxilina/química , Humanos , Doenças Periapicais , Coloração e Rotulagem/métodosRESUMO
The rat model is widely used in periodontal research and the quality of histological sections is essential. The purpose of this study was to evaluate the histological characteristics of periodontal tissues in Wistar rat maxillae, with different times of fixation and decalcified by nitric acid or formic acid (Anna Morse Solution). Fifteen rats were used. Fixation was performed for 24, 48 and 72 hours. The maxillae were hemi-sectioned and each part was decalcified either in nitric acid for 7 days or in Anna Morse solution for 35 days. Two trained and blinded examiners performed the evaluation. Fourty eight hours of fixation and decalcification with Anna Morse solution showed more clear characteristics of the epithelium-connective tissue interface and of the periodontal structures. Mean measurements between the cementum-enamel junction and the bone crest varied in the different experimental times from 176.5 (± 60.45) to 210.94 (± 39.33) pixels on the buccal aspect, and from 199.69 (± 38.33) to 298.55 (± 70.81) pixels on the palatal aspect, with no statistically significant differences (ANOVA, p > 0.05). In the same fixation period, decalcification with nitric acid or Anna Morse solution did not display any statistically significant differences. It may be concluded that for a qualitative histological analysis, fixation should preferably be for 48 hours and the demineralization should be made by Anna Morse solution. For a histomorphometric analysis, the decalcification solution does not interfere in the results.
O modelo rato é extensamente usado na pesquisa periodontal, e a qualidade dos cortes histológicos é essencial. A proposta deste estudo foi avaliar as características histológicas dos tecidos periodontais nas maxilas de ratos Wistar, após diferentes períodos de fixação e descalcificação pelo ácido nítrico ou pelo ácido fórmico (Solução de Anna Morse). Quinze ratos foram usados. A fixação foi realizada nos períodos de 24, 48 e 72 horas. As maxilas foram divididas e parte foi descalcificada em ácido nítrico durante 7 dias e parte com solução de Anna Morse por 35 dias. Dois examinadores treinados e cegos executaram a avaliação. Quarenta e oito horas de fixação e descalcificação com solução de Anna Morse mostraram características mais evidentes da interface epitélio-conjuntivo, assim como das estruturas periodontais. As médias, por vestibular, entre a junção cemento-esmalte e a crista óssea nos diferentes tempos experimentais variaram entre 176,5 (± 60,45) e 210,94 (± 39,33) "pixels", e, na face palatina, entre 199,69 (± 38,33) e 298,55 (± 70,81) "pixels", sem nenhuma diferença estatisticamente significativa (ANOVA, p > 0,05). No mesmo período de fixação, a descalcificação com ácido nítrico ou solução de Anna Morse não mostrou diferenças estatisticamente significantes. Pode-se concluir que, para a análise histológica qualitativa, a fixação deve ser preferivelmente em 48 horas e a desmineralização por solução de Anna Morse. Para a análise histo-morfométrica, a solução descalcificadora não interferiu nos resultados.
Assuntos
Animais , Masculino , Ratos , Formiatos , Ácido Nítrico/farmacologia , Doenças Periodontais/patologia , Ligamento Periodontal/patologia , Periodonto/patologia , Fixação de Tecidos/métodos , Análise de Variância , Técnica de Descalcificação , Modelos Animais de Doenças , Maxila , Microscopia Eletrônica , Ligamento Periodontal/ultraestrutura , Periodonto/efeitos dos fármacos , Periodonto , Ratos Wistar , Estatísticas não Paramétricas , Fatores de TempoRESUMO
The frequency of ciliated fibroblasts in skin, gingiva, molar and incisor periodontal ligaments and incisor enamel-related periodontium of the mouse was estimated by straight counting or by methods based on the probability of observing a basal body in relation to other cell structures. Transmission electron microscopy of ultra-thin sections mounted in single slot grids was used. The results obtained with these methods differed, but indicated that periodontal ligament fibroblasts from molars or incisors generally had a higher ciliation index than the fibroblasts from skin and gingiva. These differences may not be real since the detection of cilia and/or centriolar structures seems to depend very much upon the plane of sectioning relative to the long axis of the fibroblasts, a situation which favours the more regularly arranged periodontal fibroblasts. This arrangement makes the periodontal tissues, particularly those of rodent incisors, a valuable model for studying ciliation in vivo because of the prompt response to experimental manipulation.
Assuntos
Contagem de Células/métodos , Tecido Conjuntivo/ultraestrutura , Fibroblastos/ultraestrutura , Animais , Centríolos/ultraestrutura , Cílios , Gengiva/ultraestrutura , Incisivo/citologia , Masculino , Camundongos , Microscopia Eletrônica , Dente Molar/citologia , Ligamento Periodontal/ultraestrutura , Periodonto/ultraestrutura , Pele/ultraestruturaRESUMO
An ultrastructural study of the cementum and periodontal ligament (PDL) changes after continuous intrusion with two different and controlled forces in humans was carried out. Twelve first upper premolars, at stage 10 of Nolla, orthodontically indicated for extraction from six patients (mean age 15.3) were used. They were divided into three experimental groups, distributed intra-individually as follows: control (not moved), continuously intruded for 4 weeks with 50 or 100 cN force, utilizing a precise biomechanical model with nickel titanium super-elastic wires (NiTi-SE), which were developed and calibrated individually. The teeth were extracted, fixed, decalcified, and conventionally processed for examination in a Jeol 100 CX II transmission electron microscope. Evident signs of degeneration of cell structures, vascular components, and extracellular matrix (EM) of cementum and PDL were observed in all the intruded teeth, with more severe changes towards an apical direction and in proportion to the magnitude of force applied. Resorptive areas and an irregular root surface of the intruded teeth were noticed, according to the same pattern described above. Concomitant, areas of repair were also revealed in the cementum and PDL although the magnitude of forces remained the same throughout the experimental period. Thus, a reduction of continuous force magnitude should be considered to preserve the integrity of tissues.
Assuntos
Cemento Dentário/ultraestrutura , Ligamento Periodontal/ultraestrutura , Técnicas de Movimentação Dentária , Adolescente , Dente Pré-Molar/ultraestrutura , Fenômenos Biomecânicos , Colágeno/ultraestrutura , Ligas Dentárias , Elasticidade , Endotélio Vascular/ultraestrutura , Matriz Extracelular/ultraestrutura , Fibroblastos/ultraestrutura , Humanos , Macrófagos/ultraestrutura , Microscopia Eletrônica , Níquel , Fios Ortodônticos , Ligamento Periodontal/irrigação sanguínea , Reabsorção da Raiz/patologia , Aço Inoxidável , Estresse Mecânico , Titânio , Técnicas de Movimentação Dentária/instrumentaçãoRESUMO
Dental transplants are of great interest in modern dentistry. Research has been directed toward the study of different techniques and observations of the results. Scientific basis is also to be observed and the aim of this paper is to associate technical with scientific data. Dental germs in different stages of development were carefully removed from their alveolar cavities together with the dental sac. Trauma was observed in some areas resulting from the movements of extraction or of the removal of the dental sac by dissection. It should be noticed that by the trauma produced by removal of the dental sac is very uncommon, since the operation is performed at a mesoscopic level. The material showed that the periodontal collagen net is complex in form and the meshes are wider in the surface. Smaller meshes could be seen closer to the cementum surface. Measures could be taken in order to have a basis of the distribution of collagen material around the dental root in different levels. The results showed that extraction should be performed in a most conservative manner and the movements for extraction should be applied to the crown of the dental germ. The maintenance of the periodontal integrity is very important in order to preserve the vascular barrier created by the dental cementum