Composite inlay restorations in everyday practice

Indirect techniques and restorations, such as inlays, can be an option when tissue loss is already relevant (around 30% of the crown volume), so to facilitate restoration of the contact point and the proximal anatomy by using partial bonded restorations.

The aim of this article is to propose a very simple approach to solve deep proximal cavity cases, in which many issues have to be given an answer:

– Which material to fill the 2/3 of the height of the cavity in one wave without compromising the marginal integrity due to the stress of polymerization?

– Which cavity design to bring up the proximal and cervical margin and simplify the access for impression and bonding protocol?

– Which technique for the bonding procedure in order to go fast and being efficient?

Fig.1

Initial situation. Though the patient reports no symptom, except food impaction, the poor contact point has facilitated deep proximal decay.

Fig.2

A basic box and cavity design is performed to remove the non supported occlusal enamel and the infected dentin. Cavity cleaning is made with a mechanical action until finding resistant and hard dentin.
Once the cavity cleaning is completed a simple operative field is performed to isolate the tooth using a single hole in the rubber dam, in order to simplify the procedure, speed up the technique.
When a direct technique is used, the practitioner has to make a 3 holes rubber dam to manage the contact point, but in the present case the purpose is just to perfectly isolate the cavity and guide the filling with the dentin substitute. An automatrix with a plastic wedge is used to get the perfect fit with the deep cervical margin.

Fig.3

Once the tooth is completely isolated, the bonding procedure can start using a total etch technic (20 seconds)  with a universal adhesive system(Ecosite-Bond DMG).
The the adhesive is applied for 15 seconds with the microbrush and it is highly recommended to wait another 15 seconds in order to let the adhesive penetrate and infiltrate the collagen fibers between and inside dentin tubules.

Fig.4

A 30 seconds light curing protocol is performed before placing the dentin substitute.
The dentin substitute (LuxaCore Z Dual DMG) is injected with a Colibri+ mixer tip to fill the cavity in a single vertical motion from cervical margin to the occlusal anatomy.

Fig.5

A 2 minutes setting time for chemical curing is highly recommended to let the polymerisation stress be reduced by the slow curing of the material. After the plastic phase a light curing of 1 minute is done to improve the conversion rate of the material.

Fig.6

Matrix, wedge, and rubber dam are removed and an ideal cavity is designed in order to bring up the cervical margin, thanks to the dentin substitute used, no undercut should exist to be able to take an analogical or digital impression.
A temporary resin is used to fill the cavity during the inlay fabrication (Systemp inlay Ivoclar Vivadent).

Fig.7

Inlay is performed with composite block (LuxaCam Composite DMG) in order to:
– facilitate the milling of the inlay (easily millable compared to ceramic for small restoration)
– improve the mimicry of the final restoration with the residual tooth structure
– solve mechanical fracture of the proximal ridge thanks to the monolithic concept (mill and stain)

Surface treatment is the following for the inlay:
– sandblasting
– etching with phosphoric acid to clean and decontaminate after try-in
– adhesive system (not light cured)

The hydrofluoric acid and silane are useless because, while they’re indicated for ceramic restorations, they’re not not for composite restorations. Hydrofluoric acid may dissolve the resin matrix and reduce the physical properties of the inlay.

Bonding protocol of the inlay follow the common clinical step:
Mechanical try to check the fit of the restoration
Optical try with glycerina to check the final color

Fig.8

An individual rubber dam is used as for the laminate veneers protocol in order to go fast and being concentrated on the tooth only.

Fig.9

Then the classic step for the bonding protocol are followed:

1) Sandblasting of the cavity with 50 micron aluminum oxide particles made with dentin substitute and dentin

Fig.10

2) Etching for 25 seconds with 37% orthophosphoric acid.

Fig.11

3) Application of universal adhesive for 15 seconds (5 layers) to let the bonding penetrate through dentin and create the hybrid layer (DMG Ecosite-Bond)

4) Light curing with high power lamp (beyond 1000mW/cm2) for 45 seconds

Fig.12

Superfloss is placed under the cervical margin to remove and clean resin cement excess.

Fig.13

5) Injecting resin cement (DMG Vitique veneer B1) in the cavity.

Why using a light cured resin cement and not a self adhesive resin cement?

The use of non adhesive resin cement gives us the highest bond strength and creates the ideal homogeneity between the different layers (tooth-dentin substitute with dual cure composite resin cement with composite-composite inlay)

This way we create a single functional block effect and reinforce the residual tooth structure.

6) Placement of the inlay and removal of resin cement with brush and with superfloss in proximal area

Fig.14

Application of Optrasculpt PAD (Ivoclar Vivadent) to create pressure and perfect fit before light curing.

Fig.15

Light curing for 30 seconds on each side (occlusal, buccal and lingual).

Fig.16

Removal of rubber dam and use of blade n°12 in the proximal area to remove the small resin excess.

Fig.17

A thin diamond strip (3M) is used, under the contact point, to polish the proximal anatomy and improve the continuity between the dentin substitute and inlay.

Fig.18

Final occlusion check and polishing of the occlusal anatomy were carried out after stripping.

Fig.19

Final view after 1 week.

The papilla will need a couple of weeks to come back to the initial situation, because of the chronic food impaction it suffered  before treatment.

Conclusions

Treating dental decay is the aim of the dental job initially. Even if the incidence of dental decay has been dropping for the last 20 years, we still face many clinical situations in which deep proximal decay must to be treated.

The use of inlay restorations is well known in dentistry to treat medium and deep decay. The need of a tight contact point is the key to success and a good functional integration. A feasible and repeatable protocol, compatible with the everyday practice is mandatory.

To find the good balance between quality of work and economy. This article made some highlight regarding the clinical methodology and the choice of materials which is important too for the long term behaviour of the restoration

Bibliography

1) Bukiet F, Tirlet G. Contemporary aesthetic care for nonvital teeth: conservative treatment options. Pract Proced Aesthet Dent. 2005 Aug;17(7):467-72;

2) Sarfati A, Tirlet G. Deep margin elevation versus crown lengthening: biologic width revisited. Int J Esthet Dent. 2018;13(3):334-356.

3) Koubi S, Gurel G, Margossian P, Massihi R, Tassery H. Aspects cliniques et biomecaniques des restaurations partielles coll©es dans le traitement de lâ™usure: Les table tops. Realites Cliniques 2014. Vol. 25, n° 4 : pp. 327-336

4) Koubi S, Gurel G, Margossian P, Massihi R, Tassery H. A Simplified Approach for Restoration of Worn Dentition Using the Full Mock-up Concept: Clinical Case Reports. Int J Periodontics Restorative Dent. 2018 Mar/Apr;38(2):189-197

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