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The effectiveness of different polymerization protocols for class II composite resin restorations
Lieke C G de Jong1, Niek J M Opdam, Ewald M Bronkhorst
1Department of Preventive and Restorative Dentistry, Radboud University Nijmegen Medical Centre, P.O. Box 1901, 6500 HB Nijmegen, The Netherlands. L.deJong@dent.umcn.nl
Journal of Dentistry
|March 27, 2007
Summary
Reduced light exposure times, including 10 seconds per 2mm increment, can sufficiently cure composite resins for class II restorations. Additional lateral curing further enhances the degree of cure, optimizing polymerization efficiency.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Restorative Dentistry
Background:
- Optimizing light-curing protocols is crucial for achieving adequate polymerization of composite resins.
- Class II composite resin restorations present challenges for light penetration and uniform curing.
- Vickers hardness (VH) is a key indicator of the degree of composite resin conversion.
Purpose of the Study:
- To evaluate the impact of reduced light exposure times on the Vickers hardness of class II composite resin restorations.
- To compare the effectiveness of different light-curing units and protocols on composite resin polymerization.
- To assess the influence of extended storage time on the hardness of cured composite resins.
Main Methods:
- Class II composite resin restorations (Clearfil AP-X, Esthet-X) were fabricated in vitro using 2mm increments.
- Four light-curing protocols were applied with varying exposure times (10s, 20s, 40s) and additional lateral curing.
- Vickers hardness was measured on the axial surface directly after curing and after 7 days of storage.
Main Results:
- Directly post-curing, Vickers hardness was significantly affected by the curing protocols for both composite resins.
- After 7 days, Clearfil AP-X hardness was largely unaffected by protocols (except Smartlite), while Esthet-X showed smaller protocol-related differences.
- Reduced exposure times (10s/2mm) with high-intensity units showed potential for adequate curing under specific conditions.
Conclusions:
- Shortened light exposure times (10s/2mm) can be adequate for achieving high conversion in class II composite restorations with modern high-intensity curing units.
- Additional lateral curing significantly improves the degree of cure in class II composite resin restorations, allowing for reduced overall exposure time.
- Material choice and specific curing protocols play a role in the final hardness and conversion of composite resins.
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