RESUMO
Major histocompatibility complex (MHC) class II molecule-expressing cells are distributed in human dental pulp, and have been shown to accumulate beneath caries lesions. The responses of these cells and nerve fibers were analyzed under 5 different clinical conditions: shallow and deep experimental cavities, active and slow untreated caries, and treated caries. Under deep cavities, class II molecule-expressing dendritic cells displaced the injured odontoblasts during a period of one month, while such a response was not observed in shallow cavities and untreated or treated carious teeth. The class II molecules seen in the neural elements under active caries were no longer detectable in treated carious teeth. However, six months after treatment, clusters consisting of dendritic cells, T-lymphocytes, and nerve fibers still remained locally in the subodontoblastic area. These results indicate that dental pulps respond differently to cavity preparation and restoration between normal and caries conditions, and that immunoresponses persist for many months, even after caries treatment.
Assuntos
Células Dendríticas/patologia , Cárie Dentária/patologia , Restauração Dentária Permanente , Antígenos de Histocompatibilidade Classe II/análise , Fibras Nervosas/patologia , Adulto , Análise de Variância , Células Dendríticas/imunologia , Cárie Dentária/imunologia , Preparo da Cavidade Dentária , Polpa Dentária/imunologia , Polpa Dentária/inervação , Polpa Dentária/patologia , Dentina Secundária/imunologia , Dentina Secundária/patologia , Seguimentos , Antígenos HLA-DR/análise , Humanos , Antígenos Comuns de Leucócito/análise , Fibras Nervosas/imunologia , Odontoblastos/patologia , Linfócitos T/imunologia , Linfócitos T/patologiaRESUMO
The metallurgical structure of a non-gamma-2 amalgam was investigated by using metallurgical microscopy, surface, point, and line analyses by an electron probe microanalyzer, and a microhardness test. Referring to these findings, their effects on clinical results were then discussed. Findings were as follows: The residual dispersant particle was less hard than the gamma 1 matrix, but the ring around it was much harder than the gamma 1 matrix or the residual gamma particle. The improved mechanical properties seem to be the result of the presence of this ring. The gamma 2 phase was absent in this amalgam. The absence of gamma 2 phase seems to improve chemical resistance, to prevent the deformation by mercuroscopic expansion of amalgam margins, and thus to decrease their fracture potential. The minute gamma 1 crystals found adjacent to the ring around the residual dispersant particle seem to indicate that they were late in crystallization, resulting in low early strength.
Assuntos
Amálgama Dentário , Fenômenos Químicos , Físico-Química , Cobre/análise , Amálgama Dentário/análise , Microanálise por Sonda Eletrônica , Dureza , Prata/análise , Propriedades de Superfície , Estanho/análiseRESUMO
The dimensional factors of the cervical undercut of the human teeth were measured. The facial and lingual undercuts showed considerable deviations in depth, width, and inclination to the crown axis and the food stream. The proximal undercuts showed a uniform depth of 1 +/- 0.3 mm with some deviations in width and inclination.
Assuntos
Dente/anatomia & histologia , Dente Pré-Molar/anatomia & histologia , Dente Canino/anatomia & histologia , Humanos , Incisivo/anatomia & histologia , Dente Molar/anatomia & histologia , Odontometria , Raiz Dentária/anatomia & histologiaRESUMO
In order to find a substitute for human teeth in the adhesion test, the adhesive strength to bovine teeth was compared with that to human teeth using five dental cements and two composite resins. The adhesion to enamel and the superficial layer of dentin showed no statistically significant difference between human and bovine teeth, although the mean values were always slightly lower with bovine teeth. Adhesion to bovine dentin decreased considerably with the depth of dentin.
Assuntos
Colagem Dentária , Esmalte Dentário/anatomia & histologia , Adesividade , Animais , Bovinos , Resinas Compostas , Cimentos Dentários , Dentina/anatomia & histologia , Humanos , Microscopia Eletrônica de Varredura , Resistência à TraçãoRESUMO
We have developed a vibration etching technique in which occlusal pits and fissures are simultaneously cleansed and acid-etched using a fissure needle mounted on an electromagnetic vibrator. When tested on extracted teeth, the needle completely cleansed the fissures by removing the contents and the prismless enamel layer, and widened them to from 100 to 150 micrometers to the depth reached by the needle. The sealant penetrated readily and adhered to the reduced and etched fissure walls interlocking with resin tags.
Assuntos
Condicionamento Ácido do Dente/métodos , Colagem Dentária/métodos , Selantes de Fossas e Fissuras , Fenômenos Eletromagnéticos , Humanos , Microscopia Eletrônica de Varredura , Agulhas , Selantes de Fossas e Fissuras/administração & dosagem , Dente/anatomia & histologia , VibraçãoRESUMO
The pulpal response to a new adhesive restorative resin was histopathologically investigated using dogs, and was compared with a representative conventional resin. When filled without etching and cavity wall lining, bacterial penetration and pulpal response were less with the new resin. Lining of dentin walls and total etching of cavity walls, including dentin, caused less pulpal response under the new resin. Cavities which were totally etched and filled with the new resin showed only a slight pulpal response and no bacterial penetration.
Assuntos
Resinas Compostas/farmacologia , Polpa Dentária/efeitos dos fármacos , Cimentos de Resina , Condicionamento Ácido do Dente , Animais , Bactérias/citologia , Forramento da Cavidade Dentária , Cavidade Pulpar/microbiologia , Restauração Dentária Permanente , Cães , Fatores de TempoRESUMO
When observed by SEM, after being treated with the HCl-collagenase method, the odontoblast processes extended throughout the whole thickness of dentin in intact teeth and the whole thickness of normal and the inner carious dentin in carious teeth. Small holes and depressions were found on the processes in the transparent layer.
Assuntos
Cárie Dentária/patologia , Dentina/ultraestrutura , Odontoblastos/ultraestrutura , Adulto , Colágeno/metabolismo , Humanos , Colagenase Microbiana/farmacologia , Microscopia Eletrônica de Varredura , Dente MolarRESUMO
Non-pressure adhesion of a new adhesive restorative resin was investigated employing a new tensile test. The material was adhesive to both enamel and dentin as well as to carious dentin and showed strong adhesion to all substrates tested. Etching further increased the adhesion even to dentin.
Assuntos
Adesivos , Resinas Compostas , Colagem Dentária , Condicionamento Ácido do Dente , Adesividade , Adesivos/farmacologia , Cárie Dentária/patologia , Esmalte Dentário/ultraestrutura , Polpa Dentária/anatomia & histologia , Polpa Dentária/efeitos dos fármacos , Restauração Dentária Permanente , Análise do Estresse Dentário , Dentina/ultraestrutura , Humanos , PressãoRESUMO
Exposed dental pulp is known to possess the ability to form a hard-tissue barrier (dentin bridge). The exact mechanisms by which pulp cells differentiate into odontoblasts in this process are unknown. Fibronectin has been demonstrated to play a crucial role in odontoblast differentiation during tooth development. This study tested the hypothesis that fibronectin is involved in the initial stages of replacement odontoblast differentiation and reparative dentin formation. We observed its immunohistochemical localization during dentin bridge formation in human teeth, after pulp was capped with calcium hydroxide [Ca(OH)2]. One day after the capping, precipitation of crystalline structures was observed at the TEM level in association with cell debris at the interface between the superficial necrotic zone and underlying pulp tissue. This layer of dystrophic calcification showed positive reaction for fibronectin, and pulp cells appeared to be closely associated with this layer, seven to ten days post-operatively. At 14 days, an alignment of cells, some of which were elongated and odontoblast-like, was observed adjacent to the fibronectin-positive irregular matrix. Between the cells, corkscrew fiber-like fluorescence was visible. At 28 days, the irregular fibrous matrix was followed by the formation of tubular dentin-like matrix lined with odontoblast-like cells. Therefore, it would seem that fibronectin associated with the initially formed calcified layer might play a mediating role in the differentiation of pulp cells into odontoblasts during reparative dentinogenesis, after pulp was capped with Ca(OH)2.
Assuntos
Polpa Dentária/química , Dentina Secundária/crescimento & desenvolvimento , Dentinogênese/fisiologia , Fibronectinas/fisiologia , Adulto , Hidróxido de Cálcio , Diferenciação Celular , Polpa Dentária/ultraestrutura , Capeamento da Polpa Dentária , Dentina Secundária/ultraestrutura , Fibronectinas/análise , Imunofluorescência , Humanos , Microscopia Eletrônica , Odontoblastos/química , Odontoblastos/citologiaRESUMO
Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.
Assuntos
Células Apresentadoras de Antígenos , Cárie Dentária/imunologia , Polpa Dentária/imunologia , Dentina/imunologia , Antígenos HLA-DR/análise , Adolescente , Adulto , Dente Pré-Molar/imunologia , Polpa Dentária/citologia , Humanos , Técnicas Imunoenzimáticas , Odontoblastos/imunologia , Dente não Erupcionado/imunologiaRESUMO
The aim of this study was to determine whether microorganisms invade periapical cementum of human teeth from the adjacent periapical lesions. We therefore attempted to isolate microorganisms from periapical cementum through the adoption of standard anaerobic procedures for obligate anaerobes. Samples of cementum were taken from 10 amputated tooth roots at the time of apicoectomy. From two of these samples, bacteria were recovered after anaerobic incubation, but no bacteria were recovered after aerobic incubation of the same samples. Of a total of eight isolates from the cementum, seven were obligate anaerobes and one was aerotolerant. The obligate anaerobes isolated were assigned to the genera Prevotella, Peptostreptococcus, Eubacterium, and Fusobacterium. The aerotolerant anaerobe was Campylobacter. From this, we conclude that bacteria can successfully invade cementum via periapical periodontal tissue, and that such bacteria may play a significant role in chronic periapical pathosis.
Assuntos
Bactérias Anaeróbias/patogenicidade , Cemento Dentário/microbiologia , Doenças Periapicais/microbiologia , Actinomyces/isolamento & purificação , Adulto , Idoso , Bactérias Anaeróbias/isolamento & purificação , Bacteroides/isolamento & purificação , Campylobacter/isolamento & purificação , Doença Crônica , Eubacterium/isolamento & purificação , Cocos Gram-Positivos/isolamento & purificação , Humanos , Lactobacillus/isolamento & purificação , Pessoa de Meia-Idade , Peptostreptococcus/isolamento & purificação , Cisto Radicular/microbiologia , Streptococcus/isolamento & purificaçãoRESUMO
The effects of antibacterial drugs on bacterially contaminated dental pulps were investigated in monkeys. Class V buccal cavities with pulpal exposures were prepared and then left open to the oral environment for 24 h. The exposed pulps were capped with alpha-tricalcium phosphate (alpha-TCP) containing a mixture of antibacterial drugs. Either alpha-TCP or Ca(OH)2 was used as a control. Pulpal responses were histologically evaluated after 4 wk. Those teeth capped with alpha-TCP alone showed total pulp necrosis and bacterial growth within the pulp chamber. By contrast, the pulps capped with alpha-TCP containing mixed antibacterial drugs remained almost normal without any necrotic layer, but showed persistent absorbing response to capping materials and no signs of hard tissue barrier formation. In teeth capped with Ca(OH)2, a hard tissue barrier was formed below the exposure site, with a wide loss of pulp tissue. No inflammation was seen under the barrier. These results indicate that mixed antibacterial drugs added to alpha-TCP effectively disinfected pulpal lesions, without destroying any of the sound pulp tissue. However, hard tissue barrier formation was delayed by this mixture as compared with Ca(OH)2.
Assuntos
Capeamento da Polpa Dentária/métodos , Exposição da Polpa Dentária/complicações , Necrose da Polpa Dentária/prevenção & controle , Quimioterapia Combinada/uso terapêutico , Animais , Hidróxido de Cálcio/uso terapêutico , Fosfatos de Cálcio/uso terapêutico , Cefaclor/administração & dosagem , Ciprofloxacina/administração & dosagem , Exposição da Polpa Dentária/terapia , Necrose da Polpa Dentária/etiologia , Dentina Secundária/crescimento & desenvolvimento , Quimioterapia Combinada/farmacologia , Macaca , Metronidazol/administração & dosagem , Minociclina/administração & dosagem , Cicatrização/efeitos dos fármacosRESUMO
Degradation of phenylalanine and leucine by resting cells of Eubacterium brachy ATCC 33089 were studied under strict anaerobic conditions. The effects of metronidazole and air on the metabolism were also studied. The organism principally produced phenylpropionate and isocaproate from phenylalanine and leucine, respectively. Other products were cinnamate and phenylacetate from phenylalanine, and alpha-ketoisocaproate and isovalerate from leucine. The organism also produced hydroxylated end-products, i.e. phenyllactate from phenylalanine and hydroxyisocaproate from leucine. When metronidazole was added to the reaction mixture, the production of phenylpropionate, cinnamate, phenylacetate, isocaproate, alpha-ketoisocaproate and isovalerate was inhibited, while that of hydroxylated products was not, suggesting that the organism has metronidazole-sensitive and -tolerant pathways of metabolism. A similar inhibitory effect was also found when the reaction was done aerobically, suggesting that the inhibitory mode of metronidazole is similar to that of oxygen.
Assuntos
Eubacterium/metabolismo , Leucina/metabolismo , Metronidazol/farmacologia , Fenilalanina/metabolismo , Aerobiose , Anaerobiose , Desaminação , Eubacterium/efeitos dos fármacosRESUMO
The immunolocalization of decorin was studied by confocal laser scanning microscopy and transmission electron microscopy. In the apical area of developing teeth, labelling for decorin was found in the dental papilla cells, prodontoblasts and also in the Hertwig's epithelial cells. Mantle dentine and the initial predentine were negative. In circumpulpal dentine, intense reactivity extended along the calcification front and dentinal tubules. Fluorescence was also evident in odontoblast cell bodies and their processes in predentine. None was perceived, however, in the predentinal matrix. Faint staining was observed on the calcified dentinal matrix. Immunoelectron microscopy revealed staining for decorin in collagen fibrils lining the predentine-dentine junction, and where arrays of labelled filaments were noted orthogonal to the collagen fibrils. Staining extending from the calcification front was observed in the matrix adjacent to the dentinal tubule. The decorin observed at the calcification front might regulate the mineralization of dentinal matrix.
Assuntos
Dentina/química , Odontoblastos/química , Proteoglicanas/análise , Calcificação de Dente/fisiologia , Adulto , Decorina , Papila Dentária/química , Papila Dentária/ultraestrutura , Dentina/metabolismo , Dentina/ultraestrutura , Epitélio/química , Proteínas da Matriz Extracelular , Humanos , Microscopia Confocal , Microscopia Eletrônica , Microscopia Imunoeletrônica , Odontoblastos/ultraestrutura , Proteoglicanas/biossíntese , Raiz Dentária/química , Raiz Dentária/ultraestruturaRESUMO
The distribution of fibronectin in dental pulp was studied in developing and developed human teeth by indirect immunofluorescence using a confocal laser scanning microscope. In the apical region of developing teeth, intense fluorescence was found along the basement membrane facing the mesenchyme of Hertwig's epithelial sheath and first-formed (mantle) predentine. With further elongation of odontoblasts, fibronectin was observed between the cells, appearing as corkscrew fibres passing from the pulp into predentine parallel to the long axis of the odontoblasts. In the coronal region of developing and developed teeth a similar distribution of fibronectin was observed in the odontoblast layer. At the border zone between odontoblasts and predentine the reaction was intense, but was weak in the predentine itself. In the calcified dentinal matrix it had disappeared completely, except for the area along the dentinal tubules. The results demonstrate that fibronectin is present in the odontoblast layer during all stages of dentinogenesis. Fibronectin-positive fibrous structures between odontoblasts probably correspond to von Korff fibres, and are closely related to odontoblast differentiation and dentinogenesis.
Assuntos
Polpa Dentária/química , Fibronectinas/análise , Odontoblastos/química , Adulto , Dente Pré-Molar , Polpa Dentária/ultraestrutura , Dentinogênese , Imunofluorescência , Humanos , Microscopia , Dente Serotino , Odontoblastos/ultraestruturaRESUMO
Indirect immunofluorescence-based studies have shown similarities in the distribution patterns of fibronectin-positive fibrous structures and so-called von Korff fibres. The aim of the present study was to analyse the reactivity of fibronectin in the odontoblast layer of fully developed human teeth by means of immunoelectron microscopy. Between the odontoblasts, discrete and undulatory fibrillar fascicles with peroxidase labelling were observed. They seemed to be in contact with odontoblasts in some areas, while in others they appeared to be intervening between two neighbouring odontoblasts. Higher magnifications of the fibrillar material demonstrated axial periodic staining of about 70 nm. Peroxidase reaction of fibronectin was also recognized along the cell membrane of odontoblasts facing predentine. The fibronectin in fibrillar fascicles observed between odontoblasts would be held in place by the direct molecular interaction with collagen fibrils and contribute to the pulpward migration of these cells and maintenance of their specific morphology. At the distal end of odontoblasts, a tight seal would be maintained by means of odontoblast-fibronectin adhesion.
Assuntos
Fibronectinas/ultraestrutura , Odontoblastos/ultraestrutura , Dente/ultraestrutura , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestrutura , Adulto , Adesão Celular , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Movimento Celular , Colágeno/metabolismo , Colágeno/ultraestrutura , Polpa Dentária/citologia , Dentina/ultraestrutura , Fibronectinas/metabolismo , Humanos , Técnicas Imunoenzimáticas , Microscopia Imunoeletrônica , Odontoblastos/metabolismo , Dente/metabolismoRESUMO
A new light-activated adhesive composite has been formulated. Its shear bond strength and marginal microleakage were compared with glass ionomer cements: Fuji Ionomer Type II, Ketac-Fil and Ketac-Bond. The new material showed significantly (p < 0.05) higher bond strength to non-etched enamel (7.9 MPa) and dentin (7.3 MPa) than commercially available materials. It also performed significantly better (p < 0.05) in the microleakage test. Ease of use and the excellent marginal sealing ability of the new material are expected to allow considerable innovation in restorations of root caries, cervical erosion and other conditions where the marginal seal of the gingival cavosurface is difficult.
Assuntos
Resinas Compostas/química , Colagem Dentária , Infiltração Dentária , Adesivos Dentinários/química , Cimentos de Ionômeros de Vidro/química , Silicatos de Alumínio , Análise de Variância , Humanos , Teste de Materiais , Metacrilatos , Resistência à TraçãoRESUMO
A new formulation of a light-activated calcium hydroxide-based cavity liner was developed for this study. Its shear bond strength and marginal microleakage in a Class V cavity preparation were compared to those of commercially available light-activated liners and conventional glass ionomer liners: GC Lining Cement (GC), Ketac-Bond (ESPE), Time Line (Caulk), Vitrabond (3M), XR lonomer (Kerr), and Zionomer (DenMat). The new formulation had significantly higher shear bond strength to dentin than the commercially available materials. Its microleakage along gingival (cemento-dentin) walls was statistically equivalent to one of the other materials and significantly better than all the others.
Assuntos
Forramento da Cavidade Dentária , Infiltração Dentária/prevenção & controle , Adesivos Dentinários , Silanos , Análise de Variância , Hidróxido de Cálcio , Cimentos de Ionômeros de Vidro , Humanos , Metacrilatos , Dente Molar , Poliuretanos , Elastômeros de Silicone , Fluoreto de Sódio , Resistência à Tração , Uretana/análogos & derivadosRESUMO
The purpose of this study was to investigate the degree of pulp irritation of a newly developed light-activated fluoride-releasing adhesive resin liner using canine teeth compared to the amount caused by a negative control, zinc oxide eugenol cement (ZOE), and a positive control, silicate cement (silicate). In the cases of unexposed pulp, this experimental liner showed none, slight or moderate pulpal changes at 3 d postoperatively. At 30 and 90 d, no pulpal response to the experimental liner was detected in almost all cases. These findings were similar to the ZOE and better than the silicate. There was less evidence of pulpal irritation produced by the experimental liner. This material seems to be safe to the pulp under the conditions of this study.
Assuntos
Resinas Compostas/toxicidade , Forramento da Cavidade Dentária , Cimentos Dentários/toxicidade , Polpa Dentária/efeitos dos fármacos , Análise de Variância , Animais , Dentina Secundária , Cães , Odontoblastos/efeitos dos fármacos , Fatores de TempoRESUMO
AIM: This study was conducted to assess the teaching programmes for Class I and II composite restorations in Japanese dental schools to obtain an overview of what is being taught, the relative teaching volume, the criteria for the provision of posterior composite restorations and the placement techniques taught. DESIGN: Questionnaire forms mailed to the operative dentistry teaching departments in all 29 Japanese dental schools. RESULTS: The response rate was 93 per cent, with replies from 27 of the 29 dental schools. Twenty-five (93 per cent) responding schools taught the use of Class I and two schools stated that they did not teach the use of posterior composite restorations. One of the two schools had no plan to teach posterior composites within the next five years. The other school did not answer this question. Most schools anticipated that the proportion of teaching time devoted to posterior composite restorations would increase within the next five years. Diversities and similarities between teaching programmes were noted between Japanese, North American and European dental schools, the Japanese programmes being closer to those in Europe than those in North America. CONCLUSION: The diversities in the teaching of posterior composite restorations in Japanese dental schools are as great as in other parts of the world. Such diversities must affect the overall quality of restorations in general practice.