Brunton PA, Burke FJT, Sharif MO, Creanor S, Hosey MT, Mannocci F, Wilson NHF. Contemporary dental practice in the UK in 2008: aspects of direct restorations, endodontics and bleaching. Br Dent J. 2012; 212:63-67
Akpata ES, Sadiq W. Post-operative sensitivity in glass-ionomer versus adhesive resin-lined posterior composites. Am J Dent. 2001; 14:34-38
Akpata ES, Behbehani J. Effect of bonding systems on post-operative sensitivity from posterior composites. Am J Dent. 2006; 19:151-154
Auschill TM, Koch CA, Wolkewitz M, Hellwig E, Arweiler NB. Occurrence and causing stimuli of postoperative sensitivity in composite restorations. Oper Dent. 2009; 34:3-10
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Uctasli S, Shortall AC, Burke FJT. Effect of accelerated restorative techniques on the microleakage of Class II composites. Am Dent. 2002; 15:153-158
Burke FJT. Light curing may not be as simple as it seems!. Dent Update. 2011; 38:(3)
Given the increasing popularity of posterior composite restorations,1 it is essential that these can be placed with an absence of post-operative symptoms. However, the incidence of post-operative sensitivity associated with such restorations has been found to vary between 2% and 5%.2,3,4 Furthermore, one study of 292 posterior composite restorations reported post-operative sensitivity in 26% of MOD restorations at 24 hours, decreasing to 7% at 90 days, with this sensitivity being higher in larger cavities.5
What is the cost of such sensitivity, and how may that be avoided? Regarding the cost, there will be an emergency attendance, then perhaps a review appointment to ascertain if the sensitivity has decreased, and if/when it has not, a further appointment (45 minutes perhaps – depending on the size and complexity of the restoration) to replace the restoration. Readers can work out the cost according to their hourly rate!
How may such a problem be avoided? Let's answer that question by looking at the factors which might be involved.
First, polymerization contraction stress (which can stress cusps, causing them to be sensitive to bite upon) is a function, principally, of the actual polymerization contraction and the modulus of elasticity of the material, with a stiffer material being more likely to stress cusps than a more resilient material. This is why incremental build-up of the restoration is important when using conventional composite materials, with each increment only touching one wall at a time (Figure 1). The alternative is to use a low shrinkage stress composite. Filtek Silorane (3M ESPE, Seefeld, Germany) was such a material but it is no longer manufactured. However, new bulk fill restorative materials (which do not need a capping of composite, as did earlier bulk fill base materials, such as SDR from Dentsply), such as Filtek Bulk Fill Restorative (3M ESPE) have been found to have low shrinkage stress (WM Palin, personal communication) and have up to 5 mm depth of cure. Tetric Evo Ceram Bulk Fill (Ivoclar Vivadent, Lichtenstein), Beautifil Bulk Fill Restorative (Shofu, Kyoto, Japan) and Admira Fusion (Voco, Cuxhaven, Germany) have also been demonstrated to have low shrinkage stress in a recent publication from Garry Fleming's group in Dublin.6
A second cause is inadequate bonding to dentine and enamel, either because the bonding agent has been applied inadequately, or because the material itself has not been properly tried and tested. In this regard, self-etch/self-adhesive bonding agents are associated with less post-op sensitivity than etch and rinse materials, because it is impossible to over-etch the dentine: self-etch adhesives are associated with reduced levels of sensitivity. New Universal Bonding agents hold promise, but should be used with selective enamel etching, as there appears to be little advantage in etching the dentine with some of these materials, and over-etching the dentine is a certain way of increasing the incidence of post-op sensitivity and should therefore be avoided.
Thirdly, correct placement of the gingival increment of a Class II restoration is important, given that it is a difficult margin to monitor over time and inadequate adaptation at the gingival margin will lead to post–operative sensitivity. Care and attention in placement, plus adequate curing of this increment, is therefore essential. Indeed, if the manufacturers suggest a light cure of 30 seconds, I cure for 45, given that this increment is furthest from the light and the light is attenuated as it travels into the cavity. For conventional composite materials, application of a 1 mm layer of flowable composite seems a good idea, given that this has been shown to reduce microleakage at the gingival margin of a Class II box.7
Fourthly, inadequate curing of the restoration by using a light of insufficient intensity or its application in the wrong direction is an obvious potential cause of post-op sensitivity. Ensuring that the restoration received adequate light energy from a good light source placed in the correct position might seem elementary but is essential for success.8
Finally, it goes without saying that clinicians should use adequate isolation and use a material from a manufacturer who is experienced in the field. Money saved by purchasing a cheap alternative is negated by only one failed restoration or post-operative sensitivity.
Figure 1. For conventional composite materials, an incremental technique should be employed, with one increment touching only one wall of the cavity.
Summary
Use a low shrinkage stress composite but, if not, use incremental placement and a layer of flowable at the gingival box;
Ensure good bonding to dentine and enamel and avoid (over) etching the dentine;
Ensure good adaptation at the gingival floor of a Class II box;
Make sure that the restoration has received sufficient light;
