Insight into the role of periodontal ligament associated protein-1/asporin in the maintenance of the periodontal ligament using a rat ankylosis model.
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Date
2012
Authors
Chen, Wayne
Editors
Advisors
Sampson, Wayne John
Dreyer, Craig William
Dreyer, Craig William
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Thesis
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Abstract
The cells of the periodontal ligament have been shown to be osteogenic but under normal conditions, the PDL space remains patent without the occurrence of ankylosis. Periodontal Ligament Associated Protein-1 (PLAP-1)/Asporin is a recently discovered protein that has been suggested to play a significant role in suppressing the osteogenic tendency of the periodontal ligament and maintaining the fibrous ligamentous nature of the periodontal ligament. Furthermore, PLAP-1/Asporin has also been shown to be associated with the differentiation and mineralisation of dental pulp stem cells. In this study, the expression of PLAP-1 was investigated using a reversible ankylosis model induced by hypothermal insult. In paper 1, the principal aim was to determine the normal distribution of PLAP-1 reactivity in a normal rat maxilla and to analyse the pattern of PLAP-1 reactivity in association with the formation of ankylosis. In addition, another study (paper 2) was performed with the aim of investigating the distribution pattern of PLAP-1 within a normal rat molar pulp as well as its changes following freezing trauma. The results from the first paper showed that PLAP-1 was expressed in the PDL, dental pulp, blood vessel walls and the nasal cartilage. Not all sections obtained ankylosis. Sections which did not obtain ankylosis demonstrated no significant PLAP-1 expression differences between control and experimental sides. Sections that did obtain ankylosis yielded a tendency towards increased PLAP-1 reactivity especially near the cementum. However, it was difficult to deduce whether the relationship of PLAP-1 to the ankylotic union was associated with bone formation or resorptive activities. The results from paper two showed that PLAP-1/Asporin was expressed exclusively
within the pulp under normal conditions and appeared to be associated with the odontoblastic and cell rich zone. Following trauma, PLAP-1/Asporin expression decreased marginally (not statistically significant) alongside the dentine but increased significantly in the central pulpal region along with disruption and breakdown of the cellular structures. From the results derived, it can be concluded that PLAP-1/Asporin is indeed
expressed in several tissue/cell types and regions including the dental pulp and is not exclusively associated with the periodontal ligament. In addition, PLAP-1 appears to have a direct association with ankylosis although it is uncertain whether PLAP-1 aids in bone mineralisation or resorption. The second null hypothesis was also rejected although the change in expression of PLAP-1 within the pulp is more morphological than physiological. Results from the study also suggest that PLAP-1/Asporin does not appear to play a direct role in the formation of the tertiary dentine. Further research is required to elucidate the true role of PLAP-1 within the periodontal ligament as well as the pulp. Additional investigations are also required to gain further insight into the maintenance of the periodontal ligament.
School/Discipline
School of Dentistry
Dissertation Note
Thesis (D.Clin.Dent.) -- University of Adelaide, School of Dentistry, 2012
Provenance
Copyright material removed from digital thesis. See print copy in University of Adelaide Library for full text.