An in vitro study on the use of circumferential matrix bands in the placement of Class II amalgam restorations

• Published in: British dental journal Vol. 204; no. 6; p. E10
• Main Authors: Gilmour, A. S, James, T, Bryant, S, Gardner, A, Stone, D, Addy, L. D
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.03.2008; Nature Publishing Group
• Subjects: Bicuspid; Dental Amalgam; Dental Cavity Preparation; Dental Models; Dental Restoration, Permanent - adverse effects; Dental Restoration, Permanent - instrumentation; Dentistry; Disease Transmission, Infectious - prevention & control; Disposable Equipment; Humans; Matrix Bands; Medicine
• ISSN: 0007-0610; 1476-5373
• DOI: 10.1038/bdj.2008.135

Key Points Highlights the prevalence of the problem of overhanging Class II restorations. Highlights to readers that only having one matrix system may not be advisable in a practitioner's ability to avoid the production of overhangs. A disposable matrix system can provide a solution to remove the potential for cross-contamination and reduce the size of amalgam overhangs produced. 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. Conclusion 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.