Draw the limit – Part 1

The simplest things in dentistry can sometimes be the ones that give most problems. The Author would like to present a very simple solution for these simple cavities. There isn’t one 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, this kind of cavities were the most 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 prepare these cavities, manage the matrices, select the right material and polishing procedures for an inconspicuous and long-lasting restoration.

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Fig.1
Initial situation, two proximal carious lesions that will probably invade the aesthetic area and might create an unpleasant halo.

style italiano styleitaliano dentistry

Fig.2
The isolated field should be clean and the rubber dam must be perfectly inverted in order to avoid the dam to interfere with the matrix and wedge placement.

style italiano styleitaliano dentistry

Fig.3
In a modern approach, cavity opening is less destructive (with a more efficient enamel preservation) and more 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.

style italiano styleitaliano dentistry

Fig.4
After cavity opening, we clean with a low speed round bur and try to remove all the soft tissue. Generally all dentists, especially those who really care about tissue preservation, at this step 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.

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Fig.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. Infected tissue is 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.

style italiano styleitaliano dentistry

Fig.6
testo sotto immagineCavity 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.
The comes 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 translucent (because too much enamel was used)
c) perfect (balance was achieved)
being the last scenario the least frequent.
With a single mass approach the possible outcomes are:
a) little opaque (because the material used was more opaque than the tooth)
b) too translucent (because the material used was more translucent than the tooth)
c) perfect (opacity balance matched perfectly).
his last outcome is very frequent when working with a single shade (body) which mimics the opacity very efficiently.

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Fig.7
We place one preformed posterior matrix for each cavity (Lumicontrast, Polydentia, Switzerlad). This gives us several advantages as excellent contour and each matrix “holds” the other matrix in a convenient position. To read more about the synchronized use of matrices in anteriors read this article.

style italiano styleitaliano dentistry

Fig.8
After filling up one cavity, the matrix of that cavity is removed and the wedge will be pushed further, in order to slightly open the contact and gain space.

style italiano styleitaliano dentistry

Fig.9
Distal wall of 21 was performed and the matrix removed. This gives us a wider field to finish the cavity.

style italiano styleitaliano dentistry

Fig.10
The rest of the cavity is done with the same shade. Now we are ready for finishing and polishing.

style italiano styleitaliano dentistry

Fig.11
For this kind of cavities, is mandatory to use finishing strips. Remind that a coarse acetate matrix will perform the same work but require 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 proximal 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.

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Fig.12
Aspect after finishing and polishing. The polishing protocol was, abrasive rubber spiral wheels and polishing paste with a goat brush.

style italiano styleitaliano dentistry

Fig.13
Before and after situation. Further follow-ups will be made.

Conclusions

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.

Bibliography

Devoto W, et al. Composite in everyday practice: how to choose the right material and simplify application techniques in the anterior teeth. Eur J Esthet Dent. 2010 Spring;5(1):102-24.
Manauta J, Salat A. Layers, An atlas of composite resin stratification. Quintessence Books, 2012.
Kim BJ, et al. Shade distribution of indirect resin composites compared with a shade guide. J Dent. 2008 Dec;36(12):1054-60. Epub 2008 Oct 18.
Terry D. A. Color matching with composite resin: a synchronized shade comparison. Pract Proced Aesthet Dent 2003;15(7):515-521

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