Aim
The study assessed how well a new low‑shrinkage, TEGDMA/HEMA‑free resin composite system holds up over 6 years when used in Class II restorations (i.e. restorations between teeth, high stress). It compared two adhesive systems: a 3‑step etch‑and‑rinse adhesive vs. a 1‑step self‑etch adhesive, both HEMA‑free. docs.saremco.ch
Methods
- Participants / Restorations:
- 139 Class II composite restorations were placed in 67 patients (mean age ~ 53, range 29–82). docs.saremco.ch
- Each patient got two similar restorations: one using the “cmf” 3‑step etch‑and‑rinse adhesive with the low‑shrinkage composite (els), the other using “AdheSE One F” (ASE), a 1‑step self‑etch adhesive with the same composite. docs.saremco.ch
- Material details:
- The composite (els) is low in volumetric shrinkage (~2.3 %) and low shrinkage stress (~2.6 MPa after 30 min), and omits TEGDMA and HEMA (monomers thought to increase cytotoxic risk & contribute to polymerization‑stress) docs.saremco.ch
- Procedure:
- Restorations placed under usual dental clinic conditions (no special exclusion for high caries risk or bruxism). docs.saremco.ch
- Evaluated at baseline, then annually for 6 years, using modified USPHS criteria (anatomical form, marginal adaptation, color match, marginal discoloration, surface roughness, etc.). docs.saremco.ch
Results
- After 6 years, 135 restorations were available for review (some drop‑outs: patient deaths etc.). docs.saremco.ch
- Failures: 21 restorations failed over 6 years:
- cmf/els group (3‑step adhesive) had 8 failures (≈ 11.4 %) → annual failure rate (AFR) ~ 1.9% docs.saremco.ch
- ASE/els (1‑step adhesive) had 13 failures (≈ 20.0 %) → AFR ~ 3.3% docs.saremco.ch
- Causes of failure: Most commonly resin composite fracture, followed by recurrent caries, cusp fracture, or combination fracture + caries. Failures were more common in patients with high caries risk or parafunctional habits (e.g. bruxism). docs.saremco.ch
- Other findings:
- The 3‑step etch‑and‑rinse adhesive performed significantly better in durability than the 1‑step self‑etch one. docs.saremco.ch
- Despite lower mechanical strength in vitro for some of the tested materials, clinical durability was acceptable. docs.saremco.ch
Conclusions & Implications
- A resin composite system that eliminates TEGDMA and HEMA (thus reducing potential cytotoxic risk) and offers low shrinkage and stress can still achieve good long‑term durability in challenging posterior restorations when combined with a suitably strong adhesive (in this case, the 3‑step etch‑and‑rinse adhesive). docs.saremco.ch
- The choice of adhesive matters. Even within a good composite, the adhesive strategy (multi‑step etch & rinse vs single‑step self‑etch) affected survival rates. docs.saremco.ch
- Patient factors (caries risk, bruxism) significantly influence failure rates. docs.saremco.ch