An in vitro study on the use of circumferential matrix bands in the placement of Class II amalgam restorations.
OBJECTIVE
To compare the effectiveness of a disposable metal matrix band system and the Siqveland matrix system in the restoration of a Class II preparation with amalgam. To assess the difference in amalgam overhang produced between the two systems in vitro.


METHODS
A right maxillary first premolar with a Class II cavity preparation was duplicated in acrylic to produce a standardized cavity. Forty acrylic teeth were individually mounted in a hand-held model of an upper right quadrant and restored with amalgam by twenty dentists. Each dentist restored two replica teeth with amalgam; one using the Omni-matrix system and the other using the Siqveland matrix system. All 40 restored teeth were individually mounted on a standardised jig, viewed under a microscope, photographed and overhangs, if present, measured using Image ProPlus 4.0. A comparison of the overhangs produced by the two systems was analysed using a paired sample t-test.


RESULTS
An overhang was present in all cases. There was a significant difference in the size of the overhangs produced by the two different matrix systems (p-value 0.036). The Siqveland produced a larger overhang than the Omni-matrix system.


CONCLUSIONS
A commonly used matrix band (Siqveland), when compared to a newer, disposable system (Omni-matrix), was found to result in consistently larger overhangs during the restoration of class II preparations with amalgam. As Omni-matrix is a disposable system, the potential for cross-contamination is removed and it can, therefore, be considered a suitable replacement for the non-disposable Siqveland matrix system.
Gilmour
A S
AS
Department of Adult Dental Health, Cardiff University School of Dentistry, Heath Park, Cardiff, CF14 4XY. gilmour@cardiff.ac.uk
James
T
T
Bryant
S
S
Gardner
A
A
Stone
D
D
Addy
L D
LD
D001641:Bicuspid; D003723:Dental Amalgam; D003737:Dental Cavity Preparation; D003793:Dental Restoration, Permanent / Q000009:adverse effects / Q000295:instrumentation*; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D004209:Disposable Equipment; D006801:Humans; D008434:Matrix Bands; D003765:Models, Dental
D003723:Dental Amalgam