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Int Poster J Dent Oral Med 7 (2005), No. 2     15. June 2005

Int Poster J Dent Oral Med 2005, Vol 7 No 02, Poster 276

Reduction of Polymerization Stress of Composite Resin on Model-Cavities

Language: English

Authors:
DDS Matthias Noetzel, Prof. Dr. M. Gente, DDS Kristin Klingler
Dept. Preclinical and Maxillofacial Prothodontics, Philipps-University, Marburg

Date/Event/Venue:
March 10-13, 2004
IADR/AADR/CADR 82nd General Session
Hawaii Convention Center, Honolulu, Hawaii/USA

Introduction

Beside many advantages composite fillings are leaning to gap formation. To avoid any gap, the incremental polymerization became standard in recent times.

Objectives

The objective of this study was to visualize the stress, generated by polymerisation shrinkage, in the material of a model-cavity by a photo-elastic method. So it should be possible to compare the mechanical stress in the model-cavity material induced by different filling methods.

Material and Methods

Realistic volumed cavities (V=112mm3, C=0.92) of photoactive resin were examined by red circular polarized light. The bulk-technique, the incremental-placement and a new technique, a small volume light-insert (V=8,6mm 3) with light-guiding properties which was pre-exposed in bulk-fillings, were examined and compared. A conventional micro hybrid resin (Arabesk TOP) and an experimental nano-composite were used. A halogen lamp (850mW/cm²), a plasma-lamp (570mW/cm²) and a blue solid state laser (488nm/16mW) were used for light induced polymerization.

 

Procedure
- Bonding
- bulk filling: 20 sec exposure to the halogen-lamp from top, front and behind
- light-insert filling: 20 sec exposure only over light-insert and then 20 sec exposure to halogen-lamp from top, front and behind
- incremental filling: 20 sec halogen-lamp exposure to each layer from the top

Materials
- Types of composites:
nano-hybrid composite (experimental prototypeof GRANDIO-VOCO)
microhybrid composite (Arabesk Top-VOCO)
light-curing, one-component dentin and enamel bond (containing acetone)
- Type of lamps:
halogen-lamp (850mW/cm²)
plasma-lamp (570mW/cm²)
solid state laser


Results

The results offer the highest stress evaluation on bulk-techniques. The stress induced by incremental polymerization was reduced in comparison to bulk polymerization. The light-insert, as a new method, offers equivalent results like incremental-technique . The results were evaluated by a statistical test of Kolmogoroff-Smirnoff and showed significant differences between bulk / incremental and bulk / bulk with light-insert placement at a level of 1% [Abb.5][Abb.8]. The substituted light sources showed no significant influence.


Conclusions

The photo-elastic method allowed a comparison of the stress in cavity material induced by different filling- and processing techniques. It could prove that there is a stress reduction through incremental fillings and an equivalent effect of the light-insert. The function of this insert may be interpreted as an efficient three-dimensional soft-start technique.

Literature

  1. Gente M., Sommer AP. (1999): Verringerung der linearen Schrumpfung lichthärtbarer Komposite durch selektive Bestrahlung. Dtsch Zahnärztl Z (54) 1999; 729-731.
  2. Gente M., Sommer AP. (1999): Komponenten für die Herstellung randspaltfreier Füllungen aus lichthärtbaren plastischen Füllungsmaterialien für menschliche Zähne. Offenlegungsschrift DE 198 03 302 A 1. 1999.
  3. Ernst CP, Meyer GR, Klocker K, Willershausen B (2004): Determination of polymerization shrinkage stress by means of a photoelastic investigation. Dent Mater. 2004 May;20(4):313-21.
  4. Ernst CP, Brand N, Frommator U, Rippin G, Willershausen B.(2003): Reduction of polymerization shrinkage stress and marginal microleakage using soft-start polymerization. J Esthet Restor Dent. 2003;15(2):93-103; discussion 104.

This Poster was submitted by DDS Matthias Noetzel.

Correspondence address:
DDS Matthias Noetzel
Prof. Dr. M. Gente
Department of Preclinical and Maxillofacial Prosthodontics
School of Dental Medicine
Philipps University Marburg
Georg-Voigt-Str.3
35033 Marburg
Germany