Direct Restorations
Dentsply SDR - Self assessment
Before using any new restorative material, it is a good idea to familiarise oneself with its properties, so that the dentist can make an appropriate and informed choice for each individual clinical situation.
This page presents information on SDR as a series of short answer questions, with answers.
Basic Properties (as released by Dentsply)
• Compressive strength: 242 MPa • Flexural strength: 115Mpa • Filler: 68% filled by weight, 45% filled by volume • Fluoride release: Yes • Polymerisation shrinkage: 3.5% volume. • Polymerisation shrinkage stress: 1.5 MPa • Shelf-life: 2.5 years.
1. Which releases more Fluoride – Glass Ionomer or SDR?
Glass Ionomer releases substantially more fluoride. If one is planning a restoration where fluoride release is important (e.g. root caries in a dry mouth) a GI restoration may be more appropriate.
3. At worst, what is the typical bond strength to dentine when dealing with non-tubular (sclerotic) dentine?
It may be as low as 3 – 4 MPa. Lack of tubular structure seriously decreases bond strength to dentine.
With most composites, the polymerisation shrinkage stress is in the 3MPa – 5MPa region, This is a bit too close for comfort – the setting composite may tear away from the cavity margins as it shrinks, resulting in marginal leakage.
SDR claims only 1.5 MPa, which is less than the bond strength, so the probability of marginal leakage should be greatly reduced as this is well below the “worst” bond-strength.
8. True or false?
What determines the final shade of a restoration when SDR is used as a bulk filler under a conventional (capping) composite?
The SDR shade chosen.
false. SDR only comes in one shade. | score
0 / 1.
running total: 0 / 0
The shade of the capping composite
true. | score
0 / 1.
running total: 0 / 0
The opacity/translucency of the capping composite
true. SDR is quite translucent (this allows deep light penetration for 4mm curing depths). The capping composite needs to be relatively opaque to prevent the SDR colour "shining through". | score
0 / 1.
running total: 0 / 0
The thickness of the capping composite
true. A thicker layer of capping composite can prevent the SDR colour shining through if the capping composite is relatively translucent. | score
0 / 1.
running total: 0 / 0
9. What is the main advantage of using a flowable composite lining under an aesthetic posterior restoration?
It reduces or prevents the inclusion of air voids into the restoration, allowing a complete seal to dentine.
10. What are the two main disadvantages of conventional flowables compared to SDR?
Limited curing depth: maximum 2mm (conventional). SDR allows curing in 4mm increments.
A tendency to flow out of the cavity when being placed. SDR has a unique self-levelling property that appears independent of the angle the tooth is at.
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Before using any new restorative material, it is a good idea to familiarise oneself with its properties, so that the dentist can make an appropriate and informed choice for each individual clinical situation.