Controlled Body thickness Part 1

Is it still a dream to solve aesthetic cases with only two composite shades? Find out how gaining control over the masses we place can lead to accomplish the dream.
Achieving predictable results in aesthetic class IV restorations with the controlled body thickness technique: a simple method developed over the last four years by the StyleItaliano group.
This is the first of a series of 4 articles that will describe the Controlled Body Thickness Technique (CBT).
Not often, and not say never, exact sciences are found in dentistry that can help us with the problems we find in the daily practice. To start gaining control over something that has thousands of variables, a simple technique is proposed in order to eliminate unnecessary variables and the few variables remaining can be under clinician’s control.
The CBT technique consists of three simple rules:
1. Color matching with a custom shade guide of 0.5 mm of enamel (OUT) and 3 mm dentinal body (IN), or an already developed recipe (by a trusted partner) based on the VITA shade guide.
2. Clinical stratification with 0.5 mm of enamel (OUT) and the correspondent dentinal body (IN) with a special instrument.
3. Needed corrections must be done removing 0.5 mm of the enamel, in case the match was not perfect.
An original article by Jordi Manauta, Walter Devoto and Angelo Putignano

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Fig.1
For a sample tooth, and after color matching procedures we choose the A3 VITA shade as the closest match from the color scale. The shade guide has in fact great proximity in hue and chroma. It would be very desirable to reproduce the exact same color in the tooth we are going to restore.

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Fig.2
Immediately after figuring out the color, we went to the manufacturer instructions, where the suggestion was for a medium chroma dentin and a medium value enamel to reproduce the A3 color. Unfortunately, many of the recipes suggested by the manufacturer are based on other criteria and give different results in the clinical reality.
In this image, a personalized shade guide (My shade guide for composite, Smile Line, Switzerland) done with a 0,5 mm medium value enamel thickness and a 3mm medium value dentinal body. It is clear that in this case, the manufacturer recipe is far from ideal.

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Fig.3
A personalized shade guide with other colors is more congruent with the result we will desire, in hue chroma and opacity. Even if they are not an exact match as we can appreciate here, now the path for color and stratification is more clear and the result have much more probabilities to be good than working blind.

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Fig.4
Once the colors are chosen, it is only a matter of following a precise protocol of stratification. Many of the steps we propose here are the classic stratification steps used since the early ’90s which are still valid. Construction of the palatal wall is developed by many means, as a wax-up, a direct mock-up, modifying an old restoration or simply copying a correct anatomy already existent with a silicone index.

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Fig.5
A short bevel is prepared in the vestibular margin, followed by cleaning the cavity and bonding steps. The silicon index will be loaded with the chosen enamel, developing a thin layer which once hardened will be the base of the full restoration.

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Fig.6
After polymerizing the palatal wall, the silicon index is removed and then the proximal walls will be modeled. Generally this is done with the help of matrices and wedges, and sometimes in a case where no adjacent tooth is present freehand modeling can be done.

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Fig.7
At this stage, unless the operator is extremely skilled, a correction is often required. This is of extreme importance in order to obtain precise walls, free of overhangs and smooth.
The rules for doing this step are:
a) Low speed diamond bur
b) No water
c) Not touching the natural tooth
d) The powder caused by the but shall be removed with solvent-free bonding and air, nothing more.

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Fig.8
Once blowing air after the correction, the inhibited layer is recovered and the stratification can be continued. In this case, the dentinal stratification is followed. As we know, dentinal body thickness is the main concern for achieving the right color. A lack of dentin will mean a thick enamel and thus a gray and translucent restoration, on the other hand an excess of dentin will mean a very thin (or non-existent) enamel and thus an opaque restoration with very few chances of integration.
This is the main tip of the article: In the case of the “CBT Technique” is suggested not to lose much time stratifying many dentin increments and calculating the thickness visually, which is an extremely difficult task even for experienced people.
Instead we propose a simple way to obtain a 0,5 mm enamel on regular basis, accurately and the best of all, with little effort and quickly.
As we can see in the right of the image, the dentin is placed in one sole increment, filling in one bulk increment the whole restoration without curing yet.

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Fig.9
With the Misura instrument (LM Arte, LM instruments, Finland) the excess of dentin will be carried away from the restoration by leaning the thin part of the instrument on sound tooth and letting the thick part of the instrument press against the raw dentin material pushing away all the excess.

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Fig.10
In another angle of vision, we can see clearly how the instrument has left an ideal dentinal space which later on it will house a 0,5 mm of enamel. At this stage, and depending on how characterized we want the incisal edge, we can polymerize or work a little bit more on the mamelons.

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Fig.11
After achieving a right thickness of the dentin, and BEFORE POLYMERIZATION, mamelons can be modeled and shaped, although this is optional, it is convenient to develop them especially if the opposite tooth has all of this characterizations.

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Fig.12
Polymerization of the dentinal body. Just after the dentin is hard we can continue the stratification. Here we propose a very nice trick that can help to obtain a nice “halo” characterization without the need of special masses, just using the same dentin of the dentinal body, we can stratify a small roll of dentin on the incisal edge and cure.

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Fig.13
Finally the enamel is placed, and very much like the dentin, is placed in a bulk increment because of the already calibrated dentin, our work here consists only on following the contour of the tooth and the 0.5 enamel will be almost granted.
0.5 mm of enamel is the right balance of composite enamel, it will give a very correct translucency and opacity, making our restoration look very natural and integrated at marginal level.

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Fig.14
Finishing and polishing, looking to obtain an ideal surface morphology and overall shape is of extreme importance and makes the difference between a perfect restoration and a mediocre one, regardless of the color matching ability of the operator.
Find out more on Controlled Body thickness part 2. Parts 3 and part 4 are coming soon!

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Fig.15
Details of the incised edges achieved with only two masses, the high contrast between only dentin (incisal halo) and the area with only enamel (incisal edge) creates the effect of a highly characterized tooth.

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Fig.16
When enhancing the image in the method described by Salat et Al. (2) by reducing brightness and increasing contrast, we can appreciate better every feature of the incised edge. Two masses is more feasible than ever.

Bibliography

1. Manauta, J., Paolone, G. Devoto, W. 2013. IN ‘n’ OUT – A New Concept in Composite Stratification. Labline Magazine, 3 (2), pp. 110-127
2. Salat A, Devoto W, Manauta J. Achieving a precise color chart with common computer software for excellence in anterior composite restorations. Eur J Esthet Dent. 2011 Autumn;6(3):280-96.
3. Manauta J, Salat A. Layers, An atlas of composite resin stratification. Quintessence Books, 2012.
4. Baratieri LN. Soluciones Clinicas: Fundamentos y Técnicas. São Paulo: Livraria Santos, 2009.
5. Dietschi D, Ardu S, Krejci I. A new shading concept based on natural tooth color applied to direct composite restorations. Quintessence Int 2006:37:91–102.
6. Vanini L, Mangani F, Klimovskaia O. Conservative Restoration of Anterior Teeth. Viterbo, Italy: Acme, 200

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