Extra Low Shrinkage

els (extra low shrinkage) is a light-curing microhybrid composite with unparalleled low shrinkage stress and low volumetric shrinkage. Saremco is the pioneer in low shrinkage stress technology and clinical tests confirm its superior restorations. els extra low shrinkage is the most biocompatible direct restorative material as it does not contain co-monomers of low molecular weight such as HEMA or TEGDMA.

els clinical case 1
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els clinical case 5

The things you can't see

“C-Factor” and its impact on direct composite restorations

All light cured composites change in two ways when polymerized:

1) they create a stress or contraction force
2) their volume changes (shrinks)

The contraction stress and volumetric shrinkage created can lead to dentin adhesion weakening or failures, post-op sensitivity and, in the worst cases, tooth fractures. The ideal material will minimize both these factors in order to prevent possible problems and composite layering techniques have been developed to help offset the potential for problems.

The extent of the challenges in dealing with composite curing is further impacted by the cavity configuration, or what is called “C-Factor”. C-Factor is defined as a ratio and is the ratio of the bonded surface area to the unbonded or free surface area in a cavity preparation. This ratio becomes largest in box-like cavities (Class I), where there are five bonded walls and only one free surface. The ratio is the least when there are no surrounding walls and only one bonded surface. Actual C-Factor values are, in increasing value, 0.2, 0.5, 1.0, 2.0 and 5.0. The higher the C-Factor ratio the greater the potential negative impact due to volumetric shrinkage and contraction stress.

Most dentists have dealt with the paradox of completing a large Class II MODBL filling (lowest C-Factor) fully expecting sensitivity and getting none, and completing a Class I filling (highest C- Factor) and being surprised by post-op sensitivity. In fact they should not be surprised as it's in the Class I and Class III fillings (high C-Factor) where the negative impacts of composite shrinkage and contraction stress are the greatest.

Composite Behavior and Adhesion

Good adhesion to dentin is one of the keys in ensuring the long-term viability of direct placement composites. When thinking of adhesion to dentin it helps to think of Velcro for purposes of analogy. Dentin behaves like the fuzzy portion of Velcro (the loupes) and the dental adhesive behaves like the rough part of Velcro (the hooks). The dental adhesive “adheres” to the dentin - there is no chemical bonding occurring.

Adhesion to shallow dentin is more predictable as there is a greater surface area of dentin available to which to adhere. In deeper dentin the tubules are larger, reducing the available surface area and thereby reducing overall “bond” strengths.

els sem1

Shallow Dentin
els sem2

Deep Dentin

Therefore it's in deep cavity preparations where the impacts of volumetric shrinkage and contraction stress are felt the most. Force generated during the polymerization of the composite have the potential to weaken adhesion of the adhesive/composite to the dentin, potentially leading to post-op sensitivity and bond failures. (1, 2)

(1) Boaro, L., Goncalves, F., Guimaraes, T., Ferracane, J., Pfeifer, C., and Braga, R. Sorption, solubility, shrinkage and mechanical properties of “low shrinkage” commercial resin composites. Dental Materials 29: 398-404, 2013.

(2) Pitel, M. Low-Shrink Compiste Resins: A Review of Their History, Strategies for Managing Shrinkage, and Clinical Significance. Compendium 34(8): 578- 588, September 2013.

els Physical Advantages

No other composites on the market have the exceptional combination of low contraction stress and low volumetric shrinkage shown by els.

Contraction stress after 30 minutes (MPa)

els has the lowest contraction stress of any material available.

els low contraction stress

Volumetric shrinkage (vol. %)

els is among the best in class when it comes to volumetric shrinkage.

els low shrinkage

(Values by ACTA, Amsterdam, 2014-2015)

Regression plot: shrinkage stress, volumetric shrinkage after 30 minutes

The regression plot shown here shows that els has significantly better performance when both factors are taken into consideration.

Using els and els flow will increase the chances of success in direct placement restorations, especially in those with a high C-Factor.

(Values by ACTA, Amsterdam, 2014-2015)

Trademarks of their respective manufacturers
els acta graphic


At least one of, and sometimes both, HEMA (a monomer) and TEGDMA (a co-monomer) is added to virtually all composites and dental adhesives on the market: HEMA to improve cross-linking and TEGDMA as a dilutent to improve handling. It has been shown that HEMA and TEGDMA are released from composites after curing and studies have shown that TEGDMA and HEMA are damaging to human cells at even sub-toxic levels. (3, 4)

els is free of HEMA and TEGDMA, and as a result there are no compounds available to be released into the tissues.

(3) Paranjpe, A., Borbador, L.C.F., Wang, M., Hume, W.R., and Jewett, A. Resin Monomer 2-Hydroxyethyl Methacrylate (HEMA) is a Potent Inducer of Apoptic Cell Death in Human and Mouse Cells. J Dent Res 84(2):172-177, 2005

(4) Schweikl, H., Spagnuolo, G., and Schmalz, G. Genetic and Cellular Toxicology of Dental Resin Monomers. J Dent Res 85(10): 870-877, 2006

Eluded compounds from various dental composites

Detected co-monomers Detected co-monomers
Composites Dist. water Methanol
els n.d.* n.d.* n.d.* n.d.*
Synergy Duo Shade n.d.* 104 ± 16 n.d.* 126 ± 23
Grandio n.d.* 36 ± 5 n.d.* 68 ± 12
Tetric Evo Ceram n.d.* 57 ± 12 496 ± 77 n.d.*
Venus n.d.* 197 ± 26 n.d.* 76 ± 7
Gradia n.d.* 123 ± 18 500 ± 66 62 ± 2
Premise n.d.* 48 ± 7 n.d.* 51 ± 9

*n.d. = not detectable (below limit of detection). Triphenylstibane was detected in Tetric Evo Ceram (5 ± 2 µg/ml).

Unconverted compounds can be released from the composite and enter the body. This study was evaluated to quantify eluded compounds from various dental composites.

Clinical evaluation at 12 and 24 months

Teresa Bachanek, University of Lublin

12 months 24 months
Surface shape 96.06% a 94.12% a
Anatomical Shape 94.49% a 92.65% a
Marginal Adaptation 95.27% a 91.48% a

Percentage of restorations maintaining Alpha status as per criteria from US public health service. At 24 months, 0 restorations (of 124) were not deemed as non-acceptable (Charlie and Delta).

Water sorption and dissolution of dental composites

Dr. Maria Cattani-Lorente, Université de Genève

24h 7 days
els 0.21 ± 0.02 0.60 ± 0.01
Tetric Evoceram*: 0.31 ± 0.03 0.56 ± 0.03
3M Filtek Supreme*: 0.84 ± 0.05 1.29 ± 0.07

*Trademarks of their respective manufacturers

The things you can see

Ideal physical properties are certainly desirable but a good material also needs to have other other characteristics.

els has:

  • Great handling
  • Easy polishing
  • High sculptability
  • Best in class esthetics


Class I to V anterior and posterior restorations. Can also be used for the indirect technique.


  • Unprecedented low shrinkage stress
  • Minimum risk of micro cracks after MOD restorations
  • Excellent biological tolerance
  • Marginal integrity
  • Easily sculpted
  • Positionally stable even at 50° Celsius

Available shades

A1, A2, A2 op, A3, A3 op, A3.5/B4, A4, A4 op, B1, B2, B3, C2, C3, C4, D3, IA, IB, IT, RB, RB op, SW, SW-, SW+

Technical Data

Resin 263 mg BisGMa / BisEMa
Mineral filler content 737 mg/g BaAlBSi, silanized, ø 0,7 µm, max. 2,6 µm
Operation light resistance > 5 min at 11000 lux
Depth of cure 2.8 mm in 20 s/ 2.9 mm in 40 s (A)
Flexural strength 120 MPa
Flexural modulus 9.0 GPa
Water sorption 0.21 % (24 h) / 0.60 % (7 d) (B)
Dissolution 0.03 % (24 h) / 0.09 % (7 d) (B)
Shades matching VITA Shade Guide
Colour Stability stable according to ISO
Radio-opacity 217% Aluminium
Vickers Hardness 68 (at 0.3 mm, 7 d) (C)
Barcol Hardness 81
Polymerization shrinkage stress 2.6 MPa after 30 min.
Volumetric shrinkage 2.3 vol%
Wear 63 µm (60 d) (ACTA, ISO 14569-2) (D)
Consistency highly viscous, homogeneous paste
Appearence after curing homogeneous, smooth and shiny surfaces, compact structure
Conformity with ISO 4049, DIN, ADA, BSI fulfilled

(A) C.J. KLEVERLAAN, A.J. DE GEE, ACTA, 2002, unpublished
(B) Dr. Maria CATTANI, Universitiy of Geneva, 2005, unpublished
(C) Prof. Jean-Marc MEYER, University of Geneva, 2002, unpublished
(D) A. WERNER, A.J. DE GEE, ACTA, 2003, unpublished
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