What should be the approximate fluoride content in % of a mouth rinse when used daily?
Brain of the Week – Science
We love them because of the ease of placement and the excellent wetting of the tooth with its lower viscosity. We are tormented, however, by the constant threat of bubbles that so often appear as we syringe the material.
When the first dental resin-based composites were first introduced by 3M in 1964, they were thought of as an “amalgam substitute”. In other words, we thought that we needed to place it in little increments and pack it, sculpt it, and carve it like we did with amalgam.
When the first flowable composites were introduced in 1996,1 nobody was quite sure what to do with them, but we could see the definite advantages of an injectable material that instantly wets the tooth structure. What we have learned over time is that the more we manipulate composites, the more problems we can experience. Composite today is moving to being injected with little or no hand manipulation and flowable is an ideal injectable material.
Today at the Bioclear Learning Centers, we teach flowable composites as in integral part of nearly every composite procedure.
These images show the injection of a warmed flowable composite (e.g. 3M™ Filtek™ Supreme Ultra Flowable Restorative) which is immediately followed by an injection of warmed paste composite (e.g. 3M™ Filtek™ Supreme Ultra Universal Restorative). The complex is then light cured together. The goal is to have 95% of the load bearing and facial areas to be the 3M™ Filtek™ paste material, which has a great track record for strength and shine retention. The flowable material fills in the nooks and crannies.
Opportunistic access on the interproximal only is injection molded with 3M™ Filtek™ Bulk Fill Flowable Restorative. There is no paste composite necessary in this area because there are lower stresses on this novel restoration as it is below the contact and completely out of occlusion.
This radiograph of the discolored tooth shows a thin bonded layer of flowable covering the gutta percha to protect the seal during the inside-out bleaching protocol.
The push/pull instrument (patent pending) applies lateral pressure to create a tight contact, plus expands the matrix buccal-lingually for a broad contact. This is a more modern version of burnishing. Burnishing was a common compromise necessary with metal matrices that lack appropriate shape.
Less magnified view of the push/pull instrument. Once the matrix is expanded and pressure applied laterally to appose the matrix against the neighbor, the dental assistant cures the dots of flowable which now locks in a tight and wide contact of the matrix against the neighboring tooth.
This tooth was previously avulsed, replanted, and stabilized with the ortho bracket and wire. The endodontic isolation was made easier by using a temporary “horn” of flowable composite to keep the rubber dam pulled toward the palate.
The biggest complaint that clinicians report to me regarding flowable composites, is the bubbles that appear during syringing of the flowables. These bubbles in the flowable can be maddeningly difficult to eliminate. The bubbles are difficult to “pop” because of the viscosity of the resin. In desperation we give up on popping them and try to drag them outside of the cavity prep.
When a bubble leaves a divot on the surface of a composite, blemishes with embarrassing discoloration can occur.
There’s a lot to love about flowable composites. They’ve become integral to the modern practice for most restorative dentists. While flowable materials and modern techniques continue to improve, I also see promise in new delivery systems. I’ve been evaluating 3M’s new syringe design for their flowable composites. This new innovative design has the potential to reduce bubbles in our procedures and give dentists more control.
Brain of the Week – Science
Curing lights, prep depth, material viscosity – do you know all the factors that can impact the success of your…
Brain of the Week – History