Setting characteristics and cavity adaptation of low-shrinking resin composites.
OBJECTIVE
The aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities.


METHODS
The materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S(r)) and time at maximum strain rate (t(max)) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD(max)) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient.


RESULTS
The %S values ranged from 1.34% (FS) to 2.29% (CX), while %S(r) ranged from 0.06%s(-1) (FS) to 0.15%s(-1) (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S(r) and t(max) with %VVF (r(2)=0.884 and r(2)=0.927) and also for %S(r) and t(max) with %LD (r(2)=0.823 and r(2)=0.869).


CONCLUSIONS
%S(r) and t(max) are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.
Papadogiannis
Dimitris
D
Department of Biomaterials, School of Dentistry, University of Athens, Greece. deminho@gmail.com
Kakaboura
Afrodite
A
Palaghias
George
G
Eliades
George
G
D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D001840:Dental Bonding; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D062047:Silorane Resins; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D055114:X-Ray Microtomography
C520091:CeramX; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D011108:Polymers; D062047:Silorane Resins; C541508:clearfil majesty; C507210:premise composite resin