Regeneração tecidual guiada em recessões gengivais - o uso do enxerto gengival autógeno e das membranas de colágeno - uma revisão bibliográfica / Guided tissue regeneration in gingival recessions ­ the use of autogenous gingival enxeration and collagen membranes ­ a bibliographic review

Na odontologia atual, as recessões dos tecidos gengivais são um dos principais motivos de queixa dos pacientes nos consultórios e clínicas odontológicas. O processo de regeneração pode ser definido como a substituição dos tecidos perdidos pelos mesmos tipos teciduais originalmente existentes, recuperando totalmente a arquitetura e a função da área. As técnicas de Regeneração Tecidual Guiada (RTG) são regularmente apresentadas na literatura utilizando diversos materiais para reconstituir o tecido gengival perdido, como o enxerto gengival autógeno e as membranas de colágeno. A etiologia das recessões gengivais é de caráter multifatorial onde os fatores podem agir sozinhos ou concomitantemente. Dentre os fatores etiológicos podemos citar: a posição dos dentes na arcada, sequelas das doenças periodontais, sequelas da movimentação ortodôntica e trauma de escovação. O fato é que, a recessão dos tecidos gengivais é irreversível e pode causar defeitos e sequelas indesejáveis nos pacientes tais como, estética alterada do sorriso (dentes grandes), sensibilidade dentinária (dor) e predisposição ao desenvolvimento de doença periodontal (perda dental), pois compromete a qualidade e quantidade de gengiva ceratinizada que faz parte do periodonto de proteção. Segundo a Academia Americana de Periodontia (AAP), a dentina radicular nunca deve ficar exposta e pode ser recoberta de duas formas viáveis: 1) através de restauração com material não biológico (resina composta ou cimento ionômero de vidro); e 2) cirurgicamente com material biológico através de enxerto gengival autógeno ou membranas de colágeno. Por essa razão o objetivo do estudo foi elaborar uma revisão bibliográfica sobre a regeneração tecidual guiada visando à recuperação das recessões gengivais.(AU)

In current dentistry, recessions of gingival tissues are a major reason for patients' complaints in dental offices and clinics. The regeneration process can be defined as the replacement of tissues lost by the same tissue types originally existing, fully recovering the architecture and function of the area. Guided Tissue Regeneration (RTG) techniques are regularly presented in the literature using various materials to reconstitute lost gingival tissue, such as autogenous gingival graft and collagen membranes. The etiology of gingival recessions is multifactorial where factors can act alone or concomitantly. Among the aetiological factors we can mention: the position of the teeth in the arch, sequelae of periodontal diseases, sequelae of orthodontic movement, and brushing trauma. The fact is that the recession of the gingival tissues is irreversible and can cause undesirable defects and sequelae in patients such as altered aesthetics of the smile (large teeth), dentin sensitivity (pain) and predisposition to the development of periodontal disease (dental loss), because it compromises the quality and quantity of keratinized gingiva that is part of the periodontal protection. According to the American Academy of Periodontology (AAP), root dentin should never be exposed and can be covered in two viable ways: 1) through restoration with non-biological material (composite resin or glass ionomer cement) and 2) surgically with material through autologous gingival graft or collagen membranes. For this reason the objective of this study was to elaborate a literature review on guided tissue regeneration aiming at the recovery of gingival recessions.(AU)

Adipose-derived stem cells incorporated into platelet-rich plasma improved bone regeneration and maturation in vivo.

BACKGROUND/AIM: Some cases of tooth loss related to dental trauma require bone-grafting procedures to improve the aesthetics before prosthetic rehabilitation or to enable the installation of dental implants. Bone regeneration is often a challenge and could be largely improved by mesenchymal stem cells therapy. However, the appropriate scaffold for these cells still a problem. This study evaluated the in vivo effect of human adipose-derived stem cells incorporated into autogenous platelet-rich plasma in bone regeneration and maturation. MATERIAL AND METHODS: Adipose-derived stem cells were isolated from lipoaspirate tissues and used at passage 4. Immunophenotyping and multilineage differentiation of cells were performed and mesenchymal stem cells characteristics confirmed. Bicortical bone defects (10 mm diameter) were created in the tibia of six beagle dogs to evaluate the effect of adipose-derived stem cells incorporated into platelet-rich plasma scaffolds, platelet-rich plasma alone, autogenous bone grafts, and clot. Samples were removed 6 weeks postsurgeries and analyzed by quantification of primary and secondary bone formation and granulation tissue. RESULTS: Adipose-derived stem cells incorporated into platelet-rich plasma scaffolds promoted the highest bone formation (primary + secondary bone) (P < 0.001), the highest bone maturation (secondary bone) (P < 0.001), and the lowest amount of granulation tissue (P < 0.001). CONCLUSIONS: Adipose-derived stem cells incorporated into platelet-rich plasma scaffolds promote more bone formation and maturation, and less granulation tissue in bone defects created in canine tibia. Therefore, platelet-rich plasma can be considered as a candidate scaffold for adipose-derived stem cells to promote bone regeneration.

The use of bovine screws to promote bone formation using a tibia model in dogs.

The objective of this study was to evaluate the use of a unique resorbable bovine bone screw to stimulate bone formation. Bovine bone screws were inserted in the tibia of beagle dogs. Each animal received 8 screws, divided into groups A (screws + no membranes), B (screws + titanium reinforced membranes), and C (bone defects treated with autogenous bone grafts). Animals were killed at 2, 4, and 6 months. New bone was measured with a periodontal probe and reported an average of 7.4 mm in vertical bone gain for group B, 3.6 mm for group A, and 1.7 mm for group C. Submission to Kruskal-Wallis test showed statistical differences among groups (P < .05). Histologic examination revealed an intimate contact between the newly formed bone and the resorbing bone screws. We conclude that bovine bone screws provide an environment for new bone formation and thus may provide an alternative therapy for enhancing bone formation vertically, including for regenerative procedures as well as before implant therapy.

Development of tooth germ heterotopically grafted within the ear skin. An histological study in the rat.

The main goal of this study was the analysis of the developmental potentiality of tooth germ from late bell stage on, after its heterotopic placement within the skin. Teeth germs of newborn rats were grafted within a skin pouch of the ear of adult rats. Seven to fourteen days after grafting, dental germs developed normal dental structures in which ameloblasts and odontoblasts were well differentiated. Twenty to forty-one days after graft, the inflammatory host reaction destroyed the dental developed tissues by cell infiltration. The dentin of the grafts was of osteoid characteristics, and its size increased depending on grafting time until the complete substitution of all dental tissues. This atypical dentin showed several degrees of polymerisation from collagen fibres smooth dentin devoid near the graft a to fibres rich dentin far from the dental germ. Present results suggest that this type of dental graft could be a valuable model to study the self-development of dental tissues and the reactive mechanisms taking place after dental injuries.