Premium
Serum contamination affects the surface hardness of Portland‐type cements
Author(s) -
Mahmoud O.,
Whitworth J. M.,
McCabe J. F.
Publication year - 2008
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.1365-2591.2008.01447_8.x
Subject(s) - vickers hardness test , hardness , portland cement , materials science , gypsum , metallurgy , hardening (computing) , dentistry , composite material , cement , medicine , microstructure , layer (electronics)
Aim To compare the surface hardness of cured mineral trioxide aggregates (MTAs), Portland cements (PC) and a dental gypsum product (die stone) after mixing with the recommended solution alone or incorporating serum. Methodology Samples ( n = 3) of white MTAs (ProRoot and Angelus), white PCs (Lafarge) and dental die stone (BPB) were mixed to standard consistency with recommended solution or 50 : 50 (v/v) recommended solution : defibrinated horse serum, packed into 15 mm × 2mm Perspex moulds and stored at 37 °C/100% humidity. Vickers hardness (3/specimen: 200 g at 0.05 mm mm ‐1 ) was determined at 1 or 4 h (depending on setting time), 1, 2, 3, 7, 14, 28 and 56 days. Differences in surface hardness between materials and mixing solutions and changes over time were compared with anova and paired sample t ‐tests ( P < 0.05). Results Die stone attained full hardness within 1 day and remained constant thereafter. White PC and MTAs became significantly harder with time. Serum contamination greatly reduced the 1‐day hardness of white PC and ProRoot MTA, significantly increased the 56‐day hardness of PC and all MTAs. Conclusions The Vickers hardness of white PC and MTAs increased for extended periods after initial hardening. Portland‐type cements appeared to cure in a dissimilar manner to a gypsum‐based dental stone. The hardness of white PC was greater than that of white MTAs at all times after initial hardening. Significant serum contamination may retard the early hardening of some Portland‐type cements, but uniformly produced a significantly harder material at 56 days. The mechanisms of this action are incompletely understood. Clinically, assessing the set of MTAs at 24 h may not be warranted.