Clinical and scientific guide to fragment reattachment
It is widely known that fractures of anterior teeth are common among children, particularly those aged between 8 and 11. Many techniques and materials are available to restore uncomplicated fractured crowns. Porcelain veneers or jacket crowns require substantial sacrifice of dental structure. Resin composite materials guarantee a more conservative approach, and reattachment of the fragment is nowadays a reality. It is a faster procedure, with a better and longer lasting esthetic results, and an incisal margin wear that matches that of adjacent teeth.
The purpose of this article is to make a critical appraisal, based on scientific and clinical evidence, of the optimal technique to reattach a fragment.
Different materials (mainly dentin bonding agents, flowable composites, regular composites and dual curing resin cement), and different techniques (bevel before vs after reattachment, silicone guides vs no silicone guides) have been used for the purpose.
In this article an ex-vivo study will be shown and discussed in details to understand which is the best procedure to be used in cases where a fragment is available for reattachment.
Different methods and preparations have been proposed: bonding without preparation of the tooth/fragment, a V-shaped enamel notch both on the fragment and on the tooth; internal groove within the fragment and the remaining tooth; labial and circumferential bevel. These preparation techniques have sometimes been combined with a superficial overcontouring with composite over the fracture line, which may be circumferential or lingual. The reported results vary considerably, from fracture strength as high as that of sound teeth to only approximately 50% .
The purpose of this study by Chazine et al (2011) was to use a Shear Bond Strength (SBS) test to see if any difference could be detected when using 4 different materials and 2 different techniques for fragment reattachment.
80 freshly extracted incisors were selected, measured and cut with an Isomet Saw.
Adhesive (group 1), flowable resin composite (group 2), resin composite (group 3), dual curing resin cement (group 4) were used for the purpose. In these first four groups no post reattachment bevel was performed.
In groups 5,6,7 and 8 an additional post reattachment procedure was performed using a round bur to create a double bevel both on the tooth and on the fragment. The preparation was then filled with composite (flow then regular).
All samples were then tested and fractured.
The results clearly show that when a post reattachment technique is used, higher SBS values can be obtained.
The picture shows the difference in fracture mode. No post reattachment technique leads to a detachment. When a post reattachment technique is used, the fracture is very similar to that of a natural tooth.
The ex vivo study is a support to our clinical work. The technique shown guarantees a nice marginal integration together with a high strength to the reattached fragment.
This technique was used in the article we presented last February.
This ex-vivo study supports the following conclusions: the type of material used for re-attachment did not influence the fracture resistance, while the technique used for reattachment (post reattachment bevel) positively influenced the fracture resistance.