Direct overlay – Guided cusp reconstruction

24 Feb 2018 - 24992

Due to several factors a direct overlay might sometimes be a need in daily practice, as we often see old composite filling with the signs of secondary caries, marginal leakage and insufficient occlusal morphology. Usually flat fillings can be seen at the distal portion (first and second molars). These fillings not only look unaesthetic but they also could play a role in TMJ disorders not providing retrusive control and letting condyles go back and squeeze bilaminar zone. To prevent it we as a restorative dentists should reconstruct the occlusal morphology, which will copy the nature in the most time and cost effective way. Sometimes old composite filling are too big and even preoperatively we can definitely consider indirect reconstruction. However, there are some cases then preoperative picture seems not so bad and you and your patient decide to go direct. After an old composite and caries removal, you ends up with very sharp and thin vestibular and/or lingual walls. So you starting to explain to your patient that he needs indirect restoration which will cost extra 200$ . There are some patients that can receive it with no complains but some of them have very taught financial restrictions (this group of patients usually refuse indirect way of reconstruction even before the actual treatment but any way they need to be treated somehow, usually with direct composites). So you proceed with direct approach reduce thin walls occlusaly, try to reconstruct cusps slopes and tips having no reference points following with annoying 15 min or more occlusal contact management. After that, you will be lucky if you caught all of them in place. Below you can find step-by-step cost and time effective protocol of direct overlay manufacturing using the guided cusp reconstruction technique which will help you to overcome such problems.

Fig. 1

Tooth #2.6 old composite restoration with the presence of marginal leakage and secondary caries, very thin vestibular wall and quite sharp mesio-palatal cusp. The tooth was previously endodnotically treated with no signs of periapical inflammation on the radiogram. Treatment plan was discussed with a patient. Because of financial restrictions patient ask me to solve this problem with a direct approach. 

Fig. 2

To copy the natural cusps morphology  a A-silicon partial impression was taken. It is very important to use trays because they provide stability and the volume for your material. If you try to catch all the details without a tray just adapting a silicon over the teeth by your finger you will never get precise thick index especially on the lover jaw.  

Fig. 3

Isolation. It is better to put clamp on the distally neighboring tooth to make silicon index positioning easier. 

Fig. 4

Remove your partial impression from the tray and cut it with a blade. Your index should contain at least one mesial and one distal reference tooth and imprints the cusps morphology (tip position, slope angulation if available). 

Fig. 5

Vestibular index try in. Pay attention to clamp position and remove silicone material that interfere index passive positioning. 

Fig. 6

Palatal index try in.

Fig. 7

Initial  old composite and caries removal. Right now you can evaluate the amount of residual tooth structure. As it was noted before vestibular wall is too thin and should be reduced occlusualy. The main functional unit of the tooth – mesio-palatal cusp is too sharp.  Placing the margins here won’t be vise.  

Fig. 8

Occlusal reduction. 1,5 mm will be enough.

Fig. 9

Occlusal reduction side view

Fig. 10

Following all bonding procedures cusp should be reconstructed first. Adapt your index and mark the margins of your preparation with a probe. Then remove the index and put enamel shade composite inside it. Distribute thoroughly and extend your margins a little to provide material sticking to the tooth. To prevent material sticking to the instrument while its distribution it is recommended to use microbrush applicator wetted in enamel adhesive or modeling resin. 

Fig. 11

Adapt your index with composite on the tooth, push it firmly and polymerize. 

Fig. 12

Carefully remove the index, polymerize again and add some dentin composite at the base of your shell to prevent its accidental breaking.  

Fig. 13

Repeat the procedure with another cusp 

Fig. 14

After your cusps are build up and reinforced with dentin material you can proceed to a proximal wall

Fig. 15

Finish the restoration. Don’t forget to use air block on the final step. 

 

Conclusions

The use of guided cusp reconstruction technique can save you time and patient’s money, provide more accurate occlusal contacts and extend the lifespan of your restoration. 

Bibliography