RESUMO
BACKGROUND: following tooth extraction and immediate implant installation, the edentulous site of the alveolar process undergoes substantial bone modeling and the ridge dimensions are reduced. objective: the objective of the present experiment was to determine whether the process of bone modeling following tooth extraction and immediate implant placement was influenced by the placement of a xenogenic graft in the void that occurred between the implant and the walls of the fresh extraction socket. MATERIAL AND METHODS: five beagle dogs about 1 year old were used. The 4th premolar in both quadrants of the mandible ((4) P(4) ) were selected and used as experimental sites. The premolars were hemi-sected and the distal roots removed and, subsequently, implants were inserted in the distal sockets. In one side of the jaw, the marginal buccal-approximal void that consistently occurred between the implant and the socket walls was grafted with Bio-Oss Collagen while no grafting was performed in the contra-lateral sites. After 6 months of healing, biopsies from each experimental site were obtained and prepared for histological analyses. RESULTS: the outline of the marginal hard tissue of the control sites was markedly different from that of the grafted sites. Thus, while the buccal bone crest in the grafted sites was comparatively thick and located at or close to the SLA border, the corresponding crest at the control sites was thinner and located a varying distance below SLA border. CONCLUSIONS: it was demonstrated that the placement of Bio-Oss Collagen in the void between the implant and the buccal-approximal bone walls of fresh extraction sockets modified the process of hard tissue healing, provided additional amounts of hard tissue at the entrance of the previous socket and improved the level of marginal bone-to-implant contact.
Assuntos
Perda do Osso Alveolar/prevenção & controle , Substitutos Ósseos , Colágeno , Implantação Dentária Endóssea/métodos , Minerais , Alvéolo Dental/cirurgia , Perda do Osso Alveolar/etiologia , Animais , Densidade Óssea , Cães , Implantes Experimentais , Osseointegração , Fatores de Tempo , Extração Dentária/efeitos adversosRESUMO
The objective of the present experiment was to evaluate the effect on hard tissue modeling and remodeling of the placement of a xenograft in fresh extraction sockets in dogs. Five mongrel dogs were used. Two mandibular premolars (4P4) were hemisected in each dog, and the distal roots were carefully removed. In one socket, a graft consisting of Bio-Oss Collagen (Geistlich) was placed, whereas the contralateral site was left without grafting. After 3 months of healing, the dogs were euthanized and biopsies sampled. From each experimental site, four ground sections (two from the mesial root and two from the healed socket) were prepared, stained, and examined under the microscope. The presence of Bio-Oss Collagen failed to inhibit the processes of modeling and remodeling that took place in the socket walls following tooth extraction. However, it apparently promoted de novo hard tissue formation, particularly in the cortical region of the extraction site. Thus, the dimension of the hard tissue was maintained and the profile of the ridge was better preserved. The placement of a biomaterial in an extraction socket may promote bone modeling and compensate, at least temporarily, for marginal ridge contraction.
Assuntos
Substitutos Ósseos/uso terapêutico , Colágeno/uso terapêutico , Minerais/uso terapêutico , Alvéolo Dental/cirurgia , Processo Alveolar/patologia , Processo Alveolar/cirurgia , Animais , Dente Pré-Molar/cirurgia , Biópsia , Remodelação Óssea/efeitos dos fármacos , Tecido Conjuntivo/patologia , Cães , Inserção Epitelial/patologia , Mandíbula/patologia , Mandíbula/cirurgia , Modelos Animais , Osteogênese/efeitos dos fármacos , Periodonto/patologia , Retalhos Cirúrgicos , Fatores de Tempo , Extração Dentária , Alvéolo Dental/patologia , Transplante Heterólogo , Cicatrização/efeitos dos fármacosRESUMO
O objetivo deste estudo foi avaliar características do cemento acelular com fibras extrínsecas em humanos e em cães. Cinqüenta e dois pré-molares, 22 de humanos com média de idade de 14 anos e 30 pré-molares de cães divididos em 3 grupos etários (1, 2 e 8 anos de idade), foram incluídos no estudo. Os pré-molares foram cuidadosamente extraídos e preparados para análise histológica. O cemento acelular com fibras extrínsecas da porção mais coronal da raiz foi descrito e medidas histométricas foram realizadas. Os resultados demonstraram que o cemento acelular é morfologicamente semelhante em humanos e cães. Os resultados também mostraram que o número de fibras colágenas inseridas por 100µm de superfície radicular e a velocidade de deposição do cemento (crescimento em espessura) foram similares entre as espécies. O presente estudo sugere que o cão pode representar um modelo experimental adequado para a avaliação da formação de cemento após terapia regenerativa.
The aim of the study was to evaluate the characteristics of the acellular extrinsic fiber cementum in humans and dogs. 52 premolars, 22 of humans about 14 years old and 30 premolars of dogs divided in 3 groups (1 year old, 2 years old and 8 years oId) were used in the study. The premolars were carefully extracted and prepared to histological analysis. The acellular extrinsic fiber cementum at the most coronal portion of the root was described and histological measurements were performed. The results demonstrated that the acellular extrinsic fiber cementum in humans and dogs was morphologically similar. It was also showed that the number of inserting collagen fibers per 100µm of root surface and the cementum growth rate (thickness growth) were similar between both specimens. The present study suggests that the dog may represent an adequate experimental model for the analysis of cementum formation following regenerative therapy.