Composite resins are the most popular filling material used to date. It is easy to use and aesthetically excellent as it can resemble the color of the original teeth with a variety of color choices and also a broad indication. However, composite resins have several disadvantages, such as shrinkage due to the polymerization process with light, which can result in leakage on the edge of restoration.
Back teeth (molars) composite restoration have a higher failure rate, secondary caries incidence, and a higher frequency of replacements.聽One of the most common causes (around 73.9%) of composite restoration damage is secondary caries.聽Secondary caries is defined as caries on the surface of the teeth that are in contact with the restoration material.聽Secondary caries can be found on the surface of the enamel around the restoration material or extends along the edges.聽The cause can be from edge leakage arising from poor edge restoration due to shrinkage of the material, causing tooth sensitivity after restoration and the entry of聽Streptococcus mutans聽bacteria.聽Shrinkage due to polymerization with light will compete with the strength of the composite adhesion to the tooth structure, so it causes loose bonding between the composite and the tooth structure and form a gap at the edge of the restoration.聽The gap can be an entry point for bacteria and eventually develop into secondary caries.
In deep cavity direct restoration, there are three main challenges, such as the limited depth of “curing light” to enter which causes limited thickness of the composite placement, shrinkage due to hardening reaction, and the creation of contact areas with adjacent teeth. When composites are placed deeper than the manufacturer’s recommendations, the polymerization will not be maximal. It will also cause more significant material shrinkage and increase the risk of secondary caries.
Bulk Fill聽Composite Resins聽and聽Incremental聽Layering聽Techniques
Nowadays, almost all composite resins available on the market have the basic shrinkage properties because its composition made from methacrylate.聽Various engineering modifications were investigated to avoid edge leakage due to the shrinkage.聽One of them is an聽incremental curing聽polymerization technique聽that can produce smaller edge leaks compared to single irradiation in conventional composite resins.
The development of dentistry material has given birth to a聽bulk fill聽methacrylate composite聽which is increasingly popular because it has specific characteristics, such as right consistency, good elasticity, smaller shrinkage, and allows the entry of light into the material to a 4 mm depth.
Bulk fill composite聽has higher filler composition聽(the mass fraction of聽filler聽60.7 – 85.3%) with particle sizes varying from 0.04- 3 micrometers, so several studies classify it as nano-hybrid composite.聽Shrinkage on聽bulk fill聽composite resins聽can be reduced due to the addition of special materials.
There are two types of聽bulk fill聽composites, non-packable聽(Surefil SDR Flow, Dentsply Caulk; HyperFIL-DC Parkell; HeraeusKulzer Venus Bulk Fill), and聽packable聽(Ivoclar Vivadent Tetric Evo Ceram Bulk Fill; QuiXX, Dentsply Caulk / Dentsply International; Filtek Supreme Ultra Ultra, 3M ESPE; and Kerr Sonic Fill).
A packable聽bulk fill composite is聽placed at the bottom of the cavity as the dentin base replacement, and then on top of it, a composite is added as an enamel substitute.聽Meanwhile,聽packable bulk fill聽composites聽or also called聽non flowable聽have higher strength, but it has less adaptation to the wall of the cavity.聽Therefore, it is necessary to add a more “thinner” composite or聽ionomer resin聽liner聽to achieve better adaptation to the cavity wall.
This study uses an聽in vitro聽technique聽with premolar teeth that have been drilled as deep as 4 mm to simulate deep cavity.聽Then the restoration technique is divided into two, incremental (2 layers with a thickness of 2 mm per layer) and聽bulk fill聽(1 layer with a thickness of 4 mm).聽Leakage was examined with methylene blue, Penetration of methylene blue on the cavity wall was measured by the scoring method.聽The deeper the penetration of methylene blue, the higher the score so that the greater the shrinkage that occurs.聽The result showed incremental technique has a smaller score and is statistically significant compared to the聽bulk fill聽technique.
In this study, the use of incremental technique on聽packable bulk fill聽composites聽has succeeded in minimizing leakage on the edge. The application of this technique in daily dental practice will save dentists’ time in restoration because they only use one type of material.聽However, further research must be done to evaluate various aspects before being applied clinically, such as for its biocompatibility and physical properties.
Author: Nanik Zubaidah
Details of the research can be viewed at
Nanik Zubaidah, Maria Andisa Mayangsari, Mochamad Mudjiono (2019). Microleakage Difference between Bulk and Incremental Technique in Bulk Fill Resin Composite Restoration (In Vitro Study). Journal of International Dental and Medical Research 12(2):498-503.
