Aim: To determine the effect of removing or modifying smear layer from dentine on the Prepometer dentine thickness indicator device, which operates using electrical conductivity (Hager & Werken, Germany).
Method: Twelve third molars were prepared by reducing the crowns to a flat dentine surface. Five reference points were marked and control Prepometer readings taken using its coloured LED display. Six teeth (Group E) were treated with 18% EDTA and six (Group T) with Tubulicid (Dental Therapeutics AB, Sweden). Readings were repeated. Dentine was removed in 0.5 mm increments, readings repeated and reductions continued for each tooth until the instrument gave a reading of 10 (red), indicating the pulp was close. Teeth were sectioned and the distance from the references to the pulp was measured. Readings at each level were compared using the t-test, Wilcoxon Signed Ranks test (WSR) and Ordinal Regression (OR). SEM was used to illustrate the effects of materials on the dentine.
Results: For Group E (N = 160 pairs) t-test showed a significant (P = 0.026) difference between control and treatment scores. WSR also showed significance: E>control in 54 ranks, E< control in 33 and E = control in 73 (P =0.007). For group T (N = 155) t-test showed a highly significant (P = 0.005) difference. WSR showed T< control in 59 ranks, T> control in 37 and T = control in 59 (P =0.008).
OR showed that a red light was obtained further from the pulp with EDTA treatment than with Tubulicid. SEM showed total smear layer removal in Group E and occlusion of tubule openings in Group T.
Conclusion: Measurements of dentinal conductivity were significantly influenced by treatment with EDTA and Tubulicid. Conductivity increased after EDTA but decreased after treatment with Tubulicid, possibly owing to blocking of tubules.
| Identifer | oai:union.ndltd.org:ADTP/217855 |
| Date | January 2007 |
| Creators | Violich, Darryl Ray, n/a |
| Publisher | University of Otago. School of Dentistry |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://policy01.otago.ac.nz/policies/FMPro?-db=policies.fm&-format=viewpolicy.html&-lay=viewpolicy&-sortfield=Title&Type=Academic&-recid=33025&-find), Copyright Darryl Ray Violich |
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