Back to basics: bulk and body
Bulk fill materials are now-a-days a reality. In the posterior region they have proven to be the perfect material when used properly. This kind of materials entered the market almost a decade ago, with the skepticism of a big part of the dental community. Years of research are giving amazing results on the clinical performance of these new generation materials.
Posterior restorations are never easy and most of the time is a challenge to avoid postoperative sensitivity and achieve a long term success. Most of the time these problems are triggered by a wrong use of photo curing materials in the cavity base.
The characteristics of an ideal cavity base are the following
– low or none toxicity
– low or none contraction
– low or none stress
– high sealing power
– high bonding strength
– good polymerisation
– physical resistance
– mechanical performance
– easy to place
Conventional composites many times do not comply with these characteristics if they are used in increments of more than 2mm.
Bulk fill composites have demonstrated to be an ideal base material, giving another advantage over regular composite and cavity bases such as glass ionomer or RMGIC, and of course comfortably surpassing conventional non-adhesive cements
New bulk-fill composite materials are on the market for depths of up to 5 mm in an effort to simplify and improve placement of direct composite posterior restorations.
Depth of cure for any dental composite is a critical issue, and especially for bulk-fill composites and research is proving that with encouraging results even in critical depth conditions.
Bulkfill use for restorations under high occlusal load is subject to caution, a veneering material is highly advised, even if medium term results are encouraging, highly filled composites are still physically superior.
3D micro-computer tomography imaging has shown that the volumetric contraction and volumetric shrinkage are significative less than conventional composites, and with the correct use of adhesives this strategy is highly advisable to use this strategy.
The bulk&body technique gives the following advantages.
– Ideal material in cavity base
– Ideal material in surface
– Good polymerisation on deep layers
– Low stress and contraction on the cavity bottom
– Time saving
– Good color blending
The bulk and body technique, described in 2013 in www.styleitaliano.org follows the path of present and previous research and clinical experience of many authors. Stating thus, that this group has followed the natural logic that other authors have adopted with the use and advantages of these materials and does not claim any authorship rather than the Bulk&Body name.
Fig 1.- Initial situation, defective composite restorations on first molar and second premolar. It was decided to replace the restorations for secondary caries, infiltration, marginal gaps, fracture of the material and aesthetics.
Fig 2.- Before any intervention in proximal restorations, it is mandatory to place wedges. These wedges will give 4 useful advantages
– Seperate teeth
– move away the papilla
– Protect the rubber dam
– define the location of the cervical margin
After wedging we will start the cavity preparation. To remove the restorations we will use a diamond bur with high speed and plenty of water.
Fig 3.- After removal of the restorations, we will take a low speed round bur and remove all the caries, first with plenty of water, and in the most intimate part of the cavity, with very low speed, NO water and “touch and go´´ movements we will eliminate all the carious tissue with full visibility without heat.
We will follow an etch&dry bonding technique with selective etching of the enamel.
Fig 4.- Matrices are placed all together, but the proximal walls will not be restored simultaneously, but one by one, by building up the wall and immediately removing the matrix, that way we will be compensating the space occupied by the matrices.
Transparent matrices are often used, this anatomical solution (Hawe Adapt, Kerr) is of course very suitable for its shape, but the selection of an acetate matrix is more driven by the need of having a matrix that can fold during placement and recover its shape without visible deformation. Thing that unfortunately is impossible with metallic matrices that confers more contrast and pushing resistance.
A strong ring was used for tightening the matrices. We always need at least two types of rings, one with narrow ends and one with silicone anatomical ends, this can cover all purposes. Original G-rings and Compositight 3DXR (Garrison)
Fig 5.- This is the main tip of the article. After building up one by one the proximal walls with centripetal technique, we will get a pseudo-class-I cavity, it is a rule in this technique that the proximal wall is built with the body shade. At this point we can fill up the cavity with the bulk fill material until 1.5mm away from the margin, this usually represents a 70% of the volumetric size of the cavity. It is possible to use either flowable bulk fill materials, paste bulk fill materials or sonic extruded bulk fill materials. It is advised to use the A1-A2 bulk fill colors, darker masses can interfere with the composite color blending.
Fig 6.- Using the preferred modelling technique, in this case we used the sectional modelling technique (described in the book Layers) we will fill up the cavity and model one cusp at a time. In this case we used a composite with the opacity of a Body, the preferred color is A3, which blend systematically. Note how after polishing, the natural enamel is completely dehydrated and the restorations look not integrated, but this should not be an issue afterwards.
Fig 7.- Final aspect after rubber dam removal and occlusion control. If needed we can re-polish the areas touched with the bur.
Fig 8.- Final aspect of the restorations after some days. Look how the color that was terribly dark, now has a fair integration. Using this strategy and this stratification recipe, this is one of the worst results we can achieve, which is not bad. Making it rather reliable as well for the aesthetic reasons. Body shades have an amazing ability of blocking the masses used for the base.