Teeth are not born, and dental enamel staining with irregular features are some problems that can occur during tooth formation. Study them so wide was the objective of the Thematic Project Defects in the formation of the tooth, which was supported by FAPESP and was coordinated by Sérgio Roberto Peres Line, Department of Morphology, Faculty of Dentistry of Piracicaba, State University of Campinas (FOP-UNICAMP) in Piracicaba (SP), Brazil.
One of the objects of study was the effect of fluoride on the occurrence of spots on tooth enamel. Considered a mild malformation, this problem occurs during the formation of organic matrix and calcification of the tooth and primarily affects your enamel. Although it is basically composed of minerals, the enamel begins to form from a protein matrix, and at this stage the tooth is already suffering the action of fluoride.
We developed a method that uses polarized light microscopy and allows to study the state of aggregation of the proteins of tooth enamel, said the Line Agency FAPESP. It was known that fluoride affects tooth enamel, but the FOP team has shown how this occurs. We show that fluoride disrupts the protein matrix of enamel during its formation, he said. This part of the doctoral research composed of Alexandre Ribeiro do Espírito Santo, who studied the effects of genetic alterations on the organic matrix of tooth enamel and had fellowship from FAPESP.
Another change found in dental enamel analyzed in the project was amelogenesis imperfecta, a problem caused by mutations in different genes related to the formation of this part of the tooth. This anomaly may manifest itself in different ways, for example, an enamel hard, thin and full of irregularities.
In the most common form of the disease, the enamel comes with a soft consistency, and to be worn by chewing, and eventually disappears exposing the dentin, the inside of the tooth. Thus, the disease has also functional and aesthetic consequences because after wear can be left only a small piece of the tooth, said Line.
This part of the survey was conducted in conjunction with Pragna Patel, Institute for Genetic Medicine at the University of Southern California (USC), the United States. The teams Brazilian and North American region mapped a gene related to amelogenesis imperfecta. The genetic survey also attended the National Institutes of Health (NIH, its acronym in English). At this stage, we studied families who had people with the disease to identify genes related to its occurrence.
None of the cases tested correlated with amelogenesis imperfecta. Even so, the results are important because we analyzed all genes related to enamel formation and we now know that they alone are not responsible for the disease, indicating that other genes are involved, said Line. The analysis of genes involved in amelogenesis imperfecta was the theme of the doctoral thesis of Maria Cristina Leme Godoy dos Santos, who developed his work with Grant from FAPESP.
The team also investigated the absence of the formation process of the tooth called the dental agenesis, which is more frequent among the upper lateral incisors and third molars known as wisdom teeth. In more severe cases, a few teeth are formed, causing serious problems chewing and speaking, and those related to aesthetics.
To study this disease, the FOP team analyzed the polymorphisms of PAX9 gene called and got some of them relate to agenesis of molar teeth, especially wisdom teeth. The PAX9 has been the focus of researches of Carolina Vieira de Almeida, Cristiano Pereira Borges Saito and Liza Ramenzoni Lima, with grants from FAPESP. The work required the collection of DNA from patients attending the clinic suffering from FOP agenesis. With this, the researchers were able to compare regions of DNA with that of healthy people and, therefore, possible to identify parts involved with the disease.
Started in 2005, the work was finished in May 2010, having produced important papers like the New locus for autosomal dominant amelogeneis imperfecta on chromosome 8q24.3, published in the journal Human Genetics in 2006 and identifies the chromosome 8 as a new locus of amelogenesis imperfect.
Another work produced in the same project was accepted recently by the journal Cell Biochemistry and Function, and will be published later this year, according to Line. The FOP group intends to further studies in the regions of the PAX9 identified that were more likely to be related to dental problems. This is the focus of the study of Mariana Martins Ribeiro and Luciana Souto Mofatto - the first is Technical Training Scholarship from FAPESP and, second, Postdoctoral.
The training of human resources was a key outcome of the project, according to Line. Students who worked on this theme are now teachers at the Federal University of Parana, Federal University of Bahia and Amazonas State University, said. Line also consider upgrading the research infrastructure an important consequence of the theme. The purchase of a freezer that reaches - 70 °C and a luminometer [for measurement of luminescence] and the assembly of a cell culture room, which will be used by other areas of Unicamp, are important contributions that allowed the support of FAPESP feasible, he said.
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