Draw the limit Part 1
The simplest of dentistry can be sometimes the one that gives most problems. The Author would like to present a very simple solution for these simple cavities. There is not a single patient, at least that we know, searching for a "non aesthetic" restoration; thus, in a case of anterior proximal cavities, it is implied that the restoration will not be visible and of course not ugly.
In the Author's personal experience, these kind of cavities have been the more deceiving and aesthetically difficult, until a good method was applied.
Our third class restorations cavity guidelines – since the adhesive – era are extremely variable and not clear. In this article we would like to give useful guidance on how to prep these cavities, manage the matrices, select the right material and polishing procedures for an incospicuous and long-lasting restoration.
Img. 1 – Initial situation, two proximal carious lesions that will probably invade the aesthetic area and might create an unpleasant halo.
Img. 2 – The isolated field should be clean and thee rubber dam must be perfectly inverted in order to avoid the dam to interfere with the matrix and wedge placement.
Img. 3 – In a modern approach, the cavity opening is the less destructive (most efficient enamel preservation) and the most comfortable (better visibility to remove decay). When opening the cavities through the buccal, we break the wedge so its length will not interfere with the turbine and contrangle insertion.
Img. 4 – After cavity opening, we clean with a low speed round bur and try to remove all the soft tissue. Generally this step, and especially the professionals who care a lot about tissue preservation, underestimate the extent of the caries. So, at this stage we use a caries detector agent (can be chemical or can be by fluorescence) to highlight infected tissue. Being this a controversial subject, we suggest to be used with criteria.
Img. 5 – Wash the caries detector after no more than 10 seconds, it is imperative to follow precisely the instructions of the product, otherwise, false positives might happen.
Img. 6 – Infected tissue still visible, especially in the enamel-dentine junction. Many times this infected tissue is completely invisible to our eyes, thus it is very useful to get help of detecting agents.
Img. 7 – Cavity preparation follows a simple rule that derives from a question: does your cavity touch the transitional line angle? Yes.- Do a bevel No.- Don't do a bevel. Exception to this rule: No bevel at all if the buccal enamel is less that 1mm in thickness, the aesthetic outcome will be managed in a second step. Finally there is the issue of selecting the right color. It is not the problem of selecting the right hue, chroma or value. The real problem in these kind of restorations is the opacity of the material. A two layer approach has 3 possible outcomes a) too opaque (because too much dentin was used) b) too traslucent (because too much enamel was used) c) perfect (balance was achieved) being the last scenario the leat frequent. With a single mass approach the possible outcomes are: a) little opaque (becasue the material used was more opaque than the tooth) b) too traslucent (becasue the material used was more trasnlucent than the tooth) c) perfect (opacity balance matched perfectly). This last outcome is very frequent when working with a single shade (body) which mimics the opacity very efficiently. Read more about single shade restorations here http://www.styleitaliano.org/single-shade-anteriors
Img. 8 – We place one preformed posterior matrix for each cavity (Lumicontrast, Polydentia, Switzerlad). This gives us several advantages as excelent contour and each matrix "holds" the other matrix in a convenient position. To read more about the synchronized use of matrices in anteriors read http://www.styleitaliano.org/synchro-matrix
Img. 9 – After filling up one cavity, the matrix of that cavity is removed and the wedge will be pushed more, in order to slightly open the contact and gain space.
Img. 10 – Distal wall of 21 was performed and the matrix removed. This gives us a wider field to finish the cavity.
Img. 11 – The rest of the cavity is done with the same shade. Now we are ready to do the finishing and polishing.
Img. 12 – For these kind of cavities, is imperative to use finishing strips. Remind that a coarse acetate matrix will perform the same work but requiere much more time and effort, thus we suggest to use metallic diamond strips for the "rough" finishing, which is the most important. All the material proximally to the transitional line angle will be finished with abrasive discs and finishing strips, all the material internal to the transitional line angles will be done with low speed burs. In this case only discs and strips were used as no invasion of the transitional angle was done.
Img. 13 – Aspect after finishing and polishing. The polishing protocol was, abrasive rubber spiral wheels and polishing paste with a goat brush.
Img. 14 – Before and after situation. Further follow-ups will be made.
Margin location is critical for such aesthetic demanding restorations, when the opacity is the other critical point to understand, when working with body shades is easy to obtain from decent to perfect results with little room to failure. To accomplish a good work, finishing and polishing should be performed following carefully a precise protocol.
The single shade approach has been linked to poor quality dentistry, we cannot stress out how wrong this link is in modern dentistry, being the best choice not only in simple cases but in several other indications that we will describe in upcoming articles.