Adelaide Research and Scholarship
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|Title: ||Interradicular mineralized tissue adaptation in an aseptic necrosis model.|
|Author: ||Chang, Andrew|
|Issue Date: ||2008|
|School/Discipline: ||School of Dentistry|
|Abstract: ||This study used vital bone markers to investigate mineralized tissue adaptation in the
periodontium of rats after a hypothermic insult to their maxillary first molars. This
hypothermic insult has been shown in previous studies to induce aseptic root resorption
with variable effects on ankylosis. A secondary objective was to assess the pulpal
changes that occurred concurrent with the changes in the periodontium.
Four groups of 7, eight-week old male Sprague Dawley rats were assigned to be
euthanased at the day 7, 14, 21 and 28 observation periods. At day 0, 4 groups of 6 rats
were subject to a single 20 minute application of dry ice on their maxillary right first
molar. The remaining 1 rat within each group did not receive the dry ice. All rats were
given 2 sequential bone labels, calcein 5mg/kg and alizarin red 30mg/kg, administered
intraperitoneally 8 days apart. The timing of the labels was such that all rats were
euthanased 2 days after the last label. The rat maxillae were fixed in ethanol and
embedded undecalcified in methylmethacrylate. Ten micrometre coronal sections were
obtained through the furcation of the first molars with three of each group of ten
consecutive sections being unstained, stained with von Kossa/ hematoxylin and eosin
counterstain, or decalcified and stained with hematoxylin and eosin, respectively.
Unstained sections were viewed under fluorescence, while transmitted light microscopy
was used for the other sections. Mineral apposition rates along the bone, root and pulpal
surfaces as well as periodontal ligament width were measured using histomorphometry.
Semiquantitative measurements of the resorptive surfaces within the periodontium were also noted. Multivariate and negative binomial regression statistical analyses were used to
identify influencing variables.
A focal pattern of ankylosis was observed at days 14 and 21 in 3 rats and was not seen at
day 28. In both the treated and control teeth, appositional activity was greatest along
bone and least along the root surface. Mineral tissue apposition rates along the bone and
root surface displayed an initial spike during day 14 but declined to levels of the control
teeth by day 28. A longer time lag was observed with appositional activity in the pulp
which also displayed a declining trend towards the control teeth values by day 28.
Resorption levels along the root surface continued to remain significantly (p<0.0001)
elevated. The significantly (p<0.0001) wider periodontal ligament width in the treated
molars showed a declining trend towards that of the control teeth by day 28.
There was a temporary disturbance of mineralized tissue adaptation on the bone and root
surfaces with a recovery of cellular vitality within the periodontium and pulp and a trend
towards homeostasis of the periodontal ligament width. The null hypotheses that a single
prolonged thermal insult on a rat has no effect on mineralized tissue adaptation within the
periodontium and pulp chamber and that the periodontal ligament width within the
interradicular region does not change in response to thermal trauma induced by the
present study were rejected.|
|Advisor: ||Sampson, Wayne John|
|Dissertation Note: ||Thesis (D.Clin.Dent) - University of Adelaide, School of Dentistry, 2008|
|Keywords: ||Ankylosis; Resorption; Label; Periodontal Ligament; Rat|
|Provenance: ||Copyright material removed from digital thesis. See print copy in University of Adelaide Library for full text.|
|Call number: ||09DC C45625|
|Description (link): ||http://proxy.library.adelaide.edu.au/login?url=http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1345386|
|Appears in Collections:||Research Theses|
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