Managing the matrix in class IV restorations

Class III cavities might sometimes end up becoming class IV ones because of the extension of the carious lesion. Many strategies have been proposed to solve the problems due to lack of most of the proximal wall, the contact point and the support for the matrix.
The most difficult thing in IV class is to stabilize the matrix to rebuild the interproximal wall.
One technique to manage these cases is the Intracavity Fix, described in the Layers 2 book, which aim is to build the incisal edge first to make it work as an intracavity prop once cured, thus holding the matrix in place, while the cavity is being filled.

styleitaliano style italiano matrix fixed with flowable composite

Fig.1
Another tip to solve this problem is to use a standard posterior matrix, cut and then fixed with a drop of flowable to the adjacent tooth; in this case I used a QuickmatFLEX sectional matrix by Polydentia.

polydentia banner style italiano
polydentia banner style italiano
styleitaliano style italiano lower incisor with broken veneer

Fig.2
This patient came after breaking a veneer on tooth 31 veneer and she was waiting to remake the entire work (four lower anterior veneers).

styleitaliano style italiano isolation with rubber dam of lower anterior teeth

Fig.3
So in the meantime, we wanted to repair her 31 with a quick solution.

styleitaliano style italiano gengiva and posterior matrix for class IV restoration

Fig.4
As you can see here, the matrix was cut 2 mm higher than adjacent tooth.
With a drop of Vertise flow, I fixed the matrix as I wanted, and I used the LM Gengiva tip (LM dental) to increase visibility under isolation. Although this solution could work, I wanted to analyze another method to keep the matrix in the right place while restoring the proximal wall.

styleitaliano style italiano Unica mini deel matrix on class IV cavity

Fig.5
So I used the Unica matrix (Polydentia). You can choose between the standard Unica or the Mini Deep, depending on the kind of tooth you have to restore. The Unica Mini Deep matrix was placed on tooth 31 tooth. I used the broken piece of the veneer to calibrate the length of the tooth and I fixed it with the help of a piece cut from the handle of a microbrush fixed between the Unica’s wings.

style italiano styleitaliano polydentia matrix
style italiano styleitaliano polydentia matrix
styleitaliano style italiano sandblasting of veneer for composite repair

Fig.6
After that, I removed the fragment and I started to restore the tooth. The surface was sandblasted to prepare the surfaces: enamel, dentin and feldspathic veneer.

styleitaliano style italiano LM Solo anterior spatula modeling proximal wall

Fig.7
I created the interproximal wall with the help of the LM Solo Anterior instrument (LM dental)

styleitaliano style italiano LM Solo anterior spatula for simple shaping of composite restoration

Fig.8
After curing, I removed the matrix and I finished the restoration with the LM Solo Anterior spatula, in order to compact and shape the tooth following the mesial intact part of the veneer.

style italiano styleitaliano lm arte solo instruments
style italiano styleitaliano lm arte solo instruments
styleitaliano style italiano 3M soflex disc for finishing restorations

Fig.9
Polishing with Sof-Lex (3M).

style italiano styleitaliano 3m sof lex discs and diamond spirals polishing
style italiano styleitaliano 3m sof lex discs and diamond spirals polishing
styleitaliano style italiano tooth after veneer repair with composite

Fig.10
Final result was good integration with the others veneers.

Conclusions

I would like to stress that there are many different ways to manage a class IV restoration, yet the ingredients to success are always the same:

  • Shape. Look at the adjacent teeth and copy them.
  • Support the matrix in the right way to obtain the perfect shade with different techniques.
  • Isolation of the margin is mandatory to analyze the interproximal wall curvature.
  • Right tools and instruments make the job easier.

Bibliography

1. Manauta J, Salat A. Layers An Atlas of Composite Resin Stratification. 2012. Quintessence Pub
2. Devoto W, Saracinelli M, Manauta J. Composite in everyday practice: how to choose the right material and simplify application techniques in anterior teeth. Eur J Esthet Dent. 2010;5:102-24.
3. Ahmad I. Protocols for predictable Aesthetic Dental Restorations. Oxford: Blackwell, 2006.
4. Manauta J, Salat A, Devoto W, Putignano A. Layers2, direct composites: The StyleItaliano Clinical Secret. 2022. Quintessence Pub

style italiano styleitaliano Essential Dentistry kit online on demand course
style italiano styleitaliano Essential Dentistry kit online on demand course

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