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In vitro determination of the mechanical and chemical properties of a fibre orthodontic retainer.
MedLine Citation:
PMID:  21750241     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The aim of this study was to analyse, in vitro, the chemical and mechanical properties of a new fibre retainer, Everstick, comparing its characteristics with the requirements for an orthodontic retainer. Chemical analysis was used to examine seven fibre bundles exposed to a photocuring lamp and then to different acids and resistance to corrosion by artificial saliva fortified with plaque acids. The mechanical properties examined were tensile strength and resistance to flexural force. Ten fibre samples were tested for each mechanical analysis and the mean value and standard deviation were calculated. Wilcoxon signed rank test was used to evaluate change in weight after treatment in each group. To determine changes over time between the groups for each acid considered separately, both repeated measures analysis of variance (ANOVA) on original data and on rank transformed data were used. If the results were different, ANOVA on rank-transformed data was considered. Acetic acid was found to be the most corrosive and caused the most substance loss: both pure and at the salivary pH value. Hydrofluoric acid was the most damaging. For all acids analysed in both groups (lactic, formic, acetic, propionic), changes after treatment were statistically different between two groups (P < 0.001 for lactic, acetic, propionic; P = 0.004 for formic acid).The mean Young's modulus value was 68 510 MPa. Deformation before the fibre separated into its constituent elements (glass fibre and composite) was 3.9 per cent, stress to rupture was 1546 MPa, and resistance to bending was 534 MPa. The deflection produced over a length of 12 was 1.4 mm. The fibre bundle was attacked by acids potentially present in the oral cavity; the degree of aggressiveness depending on the acid concentration. To preserve fibre bundles long term, careful plaque control is necessary, especially in the interproximal spaces, to avoid acid formation. The tested product was found to be sufficiently strong to oppose flexural and occlusal forces.
Authors:
Armando Silvestrini-Biavati; Francesca Angiero; Francesca Gibelli; Antonio Signore; Stefano Benedicenti
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-12
Journal Detail:
Title:  European journal of orthodontics     Volume:  -     ISSN:  1460-2210     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-7-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7909010     Medline TA:  Eur J Orthod     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Orthodontics, Genoa University, Italy.
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