Fig.1
The MyCustomRings set contains everything you need to achieve perfect approximal surfaces.
Original picture curtesy of Paulo Monteiro.

Fig.2
The basis for the custom ring is the conventional sectional matrix ring, in this case the Polydentia MyRing Classico.

Fig.3
First we need to prepare the ring, cover the feet with flowable resin (MyCustom Resin).

Fig.4
Then I light cure the resin.

Fig.5
The feet of the ring are evenly covered with resin, allowing a better adaptation to the approximal surfaces.
If we have more rings, then one can be prepared like this, so I can save time during the actual treatment.

Fig.6
TIP 1: Start to do the custom ring after seating of the rubber dam. This way, positioning of the ring with the matrix will be easier.
TIP 2: Isolate the approximal surface with a water soluble gel to ensure easy detachment of the custom ring from the tooth.

Fig.7
If necessary, you can easily brake the wedge with tweezers to have the perfect size.

Fig.8
Sometimes a reduced wedge ensures easy seating of the ring.

Fig.9
Leave the wedge in place and inject some resin on the approximal tooth surface. Make sure to capture the whole approximal area. Do not polimerize the resin yet!

Fig.10
Seat the ring into the flowable resin. Ensure the best possible seating by adjusting the ring gently with your hands.

Fig.11
Add some extra resin if needed And polimerize everything together. After this, gently remove the ring from the tooth.

Fig.12
The finished custom ring, with a perfect copy of the approximal surfaces. This ring can ensure a proper adaptation of the matrix also at the axio-approximal cavity walls, replicating the original approximal surface and save time at the finishing phase.
TIP 3: If necessary, you can adapt the ring faces fith a bur or disc.

Fig.13
Keep the ring on the forceps, with the ring faces separated, to avoid damage of the custom ring faces.

Fig.14
Case No. 1
Approximal caries in tooth no. 26, a typical indication for custom ring.
Indications for custom ring
A custom ring is useful every time we have a wide approximal box extending vestibular and oral from the contact area. It is especially helpful in the upper premolar and molar area, where we can capture and replicate the asymmetric approximal surfaces. These would be difficult to reproduce with conventional sextional matrix systems.
Contraindication: there is no use for a custom ring in case of narrow approximal cavities, where the individual resin index would not reach the cavity vertical margins.

Fig.15
Pre-wedging after seating of the rubber dam.
The suggested width of the cavity is big, so a custom ring can help us.

Fig.16
Some resin added to the approximal surfaces.

Fig.17
The custom ring is finished before the start of preparation.

Fig.18
Opening of the cavity.

Fig.19
The cavity is cleaned and checked with caries detector die.

Fig.20
A suitable matrix is chosen and inserted, the custom ring is seated. In this case, slight modification of the ring was necessary before a perfect fit could be achieved.

Fig.21
After the adhesive procedure, the cavity base is lined with flowable composite and the approsimal wall is built up first with a body shade composite (centripetal build up).

Fig.22
TIP 4: You can remove the ring and matrix after polimerisation of the approximal wall, this ensures a better view and access. Leaving the wedge in place prevents bleeding.

Fig.23
Frontal view of the completed approximal ridge.

Fig.24
After this stage, the rest of the approximal box is filled with bulkfill material, and the occlusal anatomy is modeled with suitable instruments and a body shade composite.
It is clearly visible, that the excess on the approximal surface is minimal, we will barely need any finishing.

Fig.25
The restoration after initial finishing and polishing.

Fig.26
One week post-op view of the restoration.

Fig.27
One week post-op view of the restoration.

Fig.28
Case No. 2
In this case the suspected width of the approximal cavity box does not exceed the flat contact area, so a custom ring is not indicated.
Initial situation. Old restorations in teeth 35 and 36, secondary caries distal 35.

Fig.29
The operatory field is isolated with rubber dam.

Fig.30
Old restorations removed. The neighbouring approximal surfaces are protected with a special wedge.
The remnant of the old cavity liner is visible.

Fig.31
Extension of the approximal box before finishing and caries removal.

Fig.32
Cavities cleaned and the margins are finished.

Fig.33
Matrix placed. Please note the good seal of the matrix by placing the MyRing Classico without customized faces as well.

Fig.34
After selective etching of the enamel for 30sec, a sponge with 2% CHX is placed in the cavities for 1 minute to reduce MMP activity. This is followed by application of a simplified adhesive.

Fig.35
Cavity depths are measured with the Posterior Misura instrument. This ensures 1.5 mm space for the final increment. If the cavity does not reach this depth, no dentin mass is placed, the morphology can be built up by body or bulkfill material.

Fig.36
In case of tooth 36, a thin layer of flowable bulkfill material was placed on the base of the cavity to leave sufficient space for final layer.

Fig.37
Approximal ridge build up with the Posterior Misura instrument.

Fig.38
Matrix and ring removed, wedge left in place.

Fig.39
The premolar restoration is finished.

Fig.40
The lingual cusps of the molar are built up together, followed by the buccal cusps (2 in this case).

Fig.41
Finished molar restoration.

Fig.42
A minimal stain was used for the restorations to give the illusion of depth and a natural look.
This step is not necessary, in this case it took about 5 minutes.

Fig.43
The restorations after initial finishing.

Fig.44
Polished restorations after removal of rubber dam and occlusal check.

Fig.45
Restorations 1 week post op.

Conclusions

The custom rings is until now the best and only technique to copy the original approximal surfaces of the teeth to be restored. Prerequisite for the use of this technique is that the proximal surfaces should be present and enamel should be intact, so that it can be copied. It has especially good use in cavities with wide proximal boxes. In these cases, a more difficult situation can be solved with a simple and reliable tool, saving time both at the matrix placement and the finishing stage.

However in cases with narrow approximal box, where the customized part does not reach the cavity margins, similar results can be achieved with conventional simple rings as well.

Last but not least, in those situations in which the approximal surface does not have proper anatomic contour at the beginning, mainly due to previous restorations, iatrogenic damage during previous restorative procedures or defective shape, we do not have a surface to copy. In these cases, we can use other rings with prefabricated anatomic ring faces.

Bibliography

1. Bichacho N. The centripetal build-up for composite resin posterior restorations. Pract Periodontics Aesthet Dent. 1994 Apr;6(3):17-23;

2. Alleman D, Magne P. A systematic approach to deep caries removal end points: The peripheral seal concept in adhesive dentistry. Quintessence Int. 2012 March.

4. Heintze SD, Rousson V. Clinical effectiveness of direct class II restorations – a meta-analysis. J Adhes Dent. 2012 Aug;14(5):407-31.

7. Van Meerbeek B, Yoshihara K, Yoshida Y, Mine A, De Munck J, Van Landuyt KL. State of the art of self-etch adhesives. Dent Mater. 2011 Jan;27(1):17-28.