Dental Tribune Indian Edition

18 Dental Tribune Indian Edition - January 2013 DTI BRISTOL, UK: The evolutionary origin of dental structures is highly debated among experts. Now, a team of international scientists has found evidence that tooth-like structures were present in the first jawed ver- tebrates, although it had long been assumed that teeth developed later. The new findings indicate that teeth developed alongside or shortly after jaw structures. The researchers discovered the origin of both teeth and jaws through studying fossils of Compagopiscis, one of the first prehistoric jawed fish. While performing 3D microscopy, they were able to visualise every tis- sue, cell and growth line within the fish’s jaws, allowing them to study the development of the teeth, said Dr Martin Rücklin, lead author and re- searcher at the University of Bristol’s School of Earth Sciences. “This technique allowed us to obtain a perfect digital model and very detailed internal views of the fossil without destroying it,” said Prof. Marco Stampanoni of the Paul Scherrer Institute, the largest research centre for natural and engineering sciences in Switzerland. The CT scans demonstrated that some primitive fish possessed jaws with distinct dental ossifications com- posed of dentine and bone, the resear- chers said. In contrast to the hypothesis that te- eth were absent in the first jawed ver- tebrates and that they captured their prey with scissor-like jaw bones, the present study suggests that the deve- lopment of tooth and jaw structures was intimately interwoven. The research was conducted by pa- laeontologists from the University of Bristol in collaboration with experts from the Natural History Museum in London and Curtin University in Au- stralia and physicists from Switzer- land. DT Sculptured reconstruction of the placoderm Dunkleosteus, a prehistoric jawed fish. (Photo courtesy of Martin Rücklin, University of Bristol, UK) Robert Selleck DT America SAN FRANCISCO, USA: A team of Italian and Australian researches appears to have found physical proof that restorative dentistry dates to the Stone Age. The researchers identified traces of a dental filling made of bees- wax in a Neolithic human tooth disco- vered in Slovenia, and they are saying it may be the “earliest known direct evidence of [a] therapeutic-palliative dental filling.” The research findings were publi- shed Sept. 19 in PLoS ONE, the peer- reviewed, open-access journal, ac- cessible online at www.plosone.org. The team acknowledges in its paper that it cannot be absolutely certain that the beeswax filling was placed in the tooth in an effort to ad- dress a dental problem the individual was experiencing while alive. But the paper identifies that as being the most likely of the possible scenarios that would explain the presence of the substance on a worn-down tooth that otherwise would have had expo- sed dentin. “The tooth probably became very sensitive, limiting the functionality of the jaw during occlusion. The oc- clusal surface could have been filled with beeswax in an attempt to reduce the pain [by] sealing exposed dentin tubules and the fracture from changes in osmotic pressure (as occurs on con- tact with sugar) and temperature (hot or cold relative to the oral cavity),” the team wrote. The piece of jawbone with five teeth still attached was discovered long before the team’s research was conducted. It was excavated from a cave wall near the village of Loche, Istria, in Slovenia and was initially dated based on associated fauna re- mains, which traced to the Upper Pleistocene era. The team reported that the speci- men was considered to be “one of the most ancient anthropological remains from the northern-Adriatic area.” But the find had never been subjected to detailed analysis until the researchers secured permission to study the man- dible using state-of-the-art scanning technology and radiocarbon dating techniques. Permission was granted by Italy’s Natural History Museum of Trieste, to whom the original finders had donated the specimen. The mandi- ble, determined to be from a male who died in his 20s, was described by the team as, “the left portion of an isolated adult mandible bearing a canine, two premolars, and the first two molars.” The 12-person team of researchers from university and governmental facilities in Italy and Australia used synchrotron radiation computed mi- crotomography, accelerator mass spectrometry radiocarbon dating, infrared spectroscopy and scanning electron microscopy to separately analyse the tooth, bone and filling material. Based on the radiocarbon analysis, the mandible was dated to an age range of 6,655–6,400 years Before Present and the filling 6,645–6,440 years BP. The researchers listed several previously known examples of an- cient dentistry but said there was no known published documentation of the use of “therapeutic palliative substance in prehistoric dentistry.” The research team also referenced documentation on the use of beeswax as a binding agent in antiquity—and explained the substance’s ability to remain preserved for long periods of time because of its “extreme che- mical stability.” The team’s conclu- sion: “In this emerging framework of ancient dental therapeutic practi- ces, the finding of a human partial mandible associated with contempo- rary beeswax, covering the occlusal surface of a canine, could represent a possible case of therapeutic use of beeswax during the Neolithic.” In a note regarding the funding of the research project, the team wrote, “This work is part of the ICTP/ Elettra EXACT Project (Elemen- tal X-ray Analysis and Computed Tomography) funded by Friuli Vene- zia Giulia (Italy). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.” The team’s paper is titled, “Be- eswax as Dental Filling on a Neolithic Human Tooth.”DT Stone-age dental filling identified Coconut oil could reduce caries Researchers from Ireland think that coconut oil may be of great interest to the oral health industry in the future because a new study has found that its natural antibiotic properties stron- gly inhibit the growth of bacteria that cause oral infections. They suggest that the oil could be integrated into commercial dental consumer pro- ducts to combat tooth decay. In clinical tests, the research- ers discovered that coconut oil that had been treated with enzymes si- milar to those found in the digestive tract was most effective in blocking the development of most strains of Streptococcus bacteria, including Streptococcus mutans. Additional tests revealed that the same enzyme- modified variant of coconut oil was also harmful to Candida albicans, the yeast that causes oral thrush, among others.DT Growing a tooth in the future? Hopes of growing teeth have been supported by the occurrence of su- pernumerary teeth in the jaws, as well as fully developed teeth in teratomas. The issue of tooth bioengineering has been taken up again more recently, as scientific breakthroughs in the fields of genetics and developmental bio- logy have led to a completely new le- vel of understanding about how teeth develop. Basically, tooth formation is regulated by a chain of interactions between two different tissues, epi- thelium and mesenchyme. And im- portantly, we actually know that the language that cells and tissues use for communication consists of defined si- gnalling molecules. Currently, the most realistic sce- narios for tooth regeneration involve the generation of teeth from stem cells with the capability to form teeth. The technology would be based on tradi- tional experiments that demonstrated more than 40 years ago that proper teeth form when separated epithelial and mesenchymal tissues from mouse embryonic tooth germs are recombi- ned and cultured as transplants. The question of the origin of cells for human tooth bioengineering is still unanswered. Adult human teeth do contain stem cells but they may not provide a suitable source. There- fore, it is likely that non-dental cells will have to be reprogrammed for the purpose of clinical tooth regene- ration. In addition, there are several other remaining challenges such as the issues of tooth size, tooth identi- ty, crown shape, and composition of the mineralised tissues. The creation of functional roots presents perhaps the biggest challenge that needs to be addressed before bioengineering of teeth will be feasible.DT Irma Thesleff Finland Irma Thesleff is professor at the University of Helsinki’s Institute of Biotechnology. She can be con- tacted at irma.thesleff@helsinki.fi. Contact Info World News British researchers discover the origin of teeth in fish