Palaeohistology reveals an unusual periodontium and tooth implantation in a filter-feeding pterodactyloid pterosaur, Pterodaustro guinazui, from the Lower Cretaceous of Argentina.

Pterosaurs are an extinct group of Mesozoic flying reptiles, which exhibited high diversity with regard to their dentition. Although morphological features of pterosaur dentition have been described in detail in several contributions, the histology of tooth and tooth attachment tissues (i.e. periodontium) has been scarcely analysed to date for this clade. Here we describe and interpret the microstructure of the tooth and periodontium attachment tissues of Pterodaustro guinazui, a filter-feeding pterodactyloid pterosaur from the Lower Cretaceous of Argentina. The histological analysis of the lower jaw and its filamentous teeth verifies that the geometry of the implantation corresponds to an aulacodont condition (i.e. teeth are set in a groove with no interdental separation). This pattern departs from that recorded in other archosaurs, being possibly also present in other, non-closely related, pterosaurs. Regarding tooth attachment, in contrast to other pterosaurs, there is no direct evidence for gomphosis in Pterodaustro (i.e. the absence of cementum, mineralized periodontal ligamentum and alveolar bone). Nevertheless, the current evidence for ankylosis is still not conclusive. Contrary to that reported for other archosaurs, replacement teeth are absent in Pterodaustro, which is interpreted as evidence for monophyodonty or diphyodonty in this taxon. Most of the microstructural features are possibly related to the complex filter-feeding apparatus of Pterodaustro and does not appear to represent the general pattern of pterosaurs.

Whole Tooth Regeneration: Can Animal Studies be Translated into Clinical Application?

Tooth loss leads to several oral problems and although a large number of treatments have been proposed to rehabilitate partially or totally edentulous patients, none of them is based on replacement of a missing tooth by a new natural whole tooth. In the field of tissue engineering, some animal models have been developed to regenerate a natural tooth in the oral cavity. This review shows the state of the art in whole tooth regeneration based on data from in vivo studies. A systematic scoping review was conducted to evaluate studies that described whole-tooth regeneration and eruption in the oral cavity. The data demonstrated that over 100 animals were used in experimental studies and all of them received implants of tooth germs constructed by bioengineering processes. Mini pigs and pigs were used in four studies followed by mice (n = 1) and dog (n = 1). Over 58 (44%) animals showed whole tooth eruption around 3.5 months after tooth germ implantation (1 to 13.5 months). Most of specimens revealed the presence of odontoblasts, dentin, dentinal tubules, dental pulp, root analogue, cementum, blood vessels, and alveolar bone. It could be concluded that in vivo whole tooth regeneration was proved to be possible, but the challenge to overcome translational barriers and test these approaches in humans still remains. Impact Statement Advances in tissue engineering have led to the development of new methods to regenerate and replace tissues and organs, including teeth. Tooth regeneration is the main goal for the replacement of tooth loss and therefore current evidence showed that tissue engineering might provide this treatment in future.

New insights into patterns and rates of tooth replacement in serrasalmid and characid fishes, with implications for the subsistence fishery of Peru's remote ribereños villages.

We explored patterns, rates and unexpected socio-ecological consequences of tooth replacement in serrasalmids and characids of the Peruvian Amazon using microcomputed tomography. Of 24 specimens collected in February 2019, representing a mix of red-bellied piranha Pygocentrus nattereri, redeye piranha Serrasalmus rhombeus, silver dollar fish Ctenobrycon hauxwellianus and mojara Astyanax abramis, six individuals possessed edentulous jaw quadrants. On average, 22.9% of fish collected per day from these species featured incomplete dentition, a value three to five times higher than anticipated based on replacement rates estimated from captive fish, differences that may be driven by ontogeny, seasonality or environmental quality.

Development of a three-dimensional tissue construct from dental human ectomesenchymal stem cells: in vitro and in vivo study.

Application of regenerative medicine technology provides treatment for patients with several clinical problems, like loss of tissue and its function. The investigation of biological tooth replacement, dental tissue engineering and cell culture, scaffolds and growth factors are considered essential. Currently, studies reported on the making of threedimensional tissue constructs focused on the use of animal cells in the early stages of embryogenesis applied to young biomodels. The purpose of this study was the development and characterization of a three-dimensional tissue construct from human dental cells. The construct was detached, cultured and characterized in mesenchymal and epithelial cells of a human tooth germ of a 12 year old patient. The cells were characterized by specific membrane markers (STRO1, CD44), making a biocomplex using Pura Matrix as a scaffold, and it was incubated for four days and transplanted into 30 adult immunosuppressed male Wistar rats. They were evaluated at 6 days, 10 days and 2 months, obtaining histological sections stained with hematoxylin and eosin. Cell cultures were positive for specific membrane markers, showing evident deviations in morphology under phase contrast microscope. Differentiation and organization were noted at 10 days, while the constructs at 2 months showed a clear difference in morphology, organization and cell type. It was possible to obtain a three-dimensional tissue construct from human dental ectomesenchymal cells achieving a degree of tissue organization that corresponds to the presence of cellular stratification and extracellular matrix.

12 a 15 anos de avaliação longitudinal do sistema de implantes Branemark e próteses unitárias cimentadas / A 12 to 15 years longitudinal study of the Branemark system and cemented single prosthesis

Este estudo mostra o acompanhamento clínico e radiográfico de 12 a 15 anos de 58 implantes unitários do sistema Branemark de plataforma regular (3,75 ou 4mm de diâmetro), instalados em pacientes dos gêneros masculino e feminino, em áreas de incisivos, caninos, pré-molares e molares e restaurados com pilares de titânio CeraOne e coroas AllCeram ou metalocerâmicas. Os resultados revelam elevado percentual de sucesso para os implantes (98,3%) e para as próteses cimentadas sobre os pilares CeraOne (96,5%). Poucos problemas foram encontrados, como: 3 casos de afrouxamento de parafuso do pilar CeraOne, 1 caso de fratura de implante por hábitos parafuncionais, 2 casos de fratura da coroa de porcelana e 1 caso envolvendo formação de fístula. Dentro das limitações deste estudo, pode-se concluir que: com este sistema de implantes é possível obter bons resultados funcionais e estéticos, a médio e longo prazo, desde que os protocolos cientificamente estabelecidos sejam observados.

This study shows a 12 to 15 year clinical and radiographic follow-up on 58 Branemark system single implants using regular platform (3.75 or 4mm of diameter), installed in male and female patients, in incisor, canine, pre-molar and molar area, and restored with CeraOne abutments and AllCeram or metalceramic crowns. The results revealed a high success rate for implants (98.3%) as well as for the prosthesis cemented over the CeraOne abutments (96.5%). Very few problems were encountered as: 3 unscrewing cases of CeraOne abutment, 1 case of implant fracture in patient with parafunctional habits, 2 cases of porcelain crown fracture and 1 case involving fistula formation. Among the Iimitations of this study, it can be concluded that with this implant system it is possible to obtain good functional and aesthetic results mid and long term as Iong as scientifically established protocols are followed.