Clinical case

The 40-year-old male patient was referred to my office before an orthodontic and prosthetic treatment. Intra-oral examination (Figs. 1 & 2) revealed:

• tetracycline discoloration;
• multiple extensive composite restorations with marginal leakage;
• primary and secondary carious lesions; and
• significant mechanical weakness (mesio-occluso-distal cavities, cusp loss, cracks).^7, 8

Based on a clinical and radiographic examination (Fig. 3), it was decided to restore the maxillary right first molar with a direct overlay, which would serve as a long-term temporary restoration for the duration of the orthodontic treatment. Once the local anaesthetic had been administered, a dental dam was placed in the upper right quadrant and the cusps of the affected first molar were reduced. For subgingival tooth preparation, the dental dam sheet was temporarily moved behind the maxillary second molar (Fig. 4). To obtain a good emergence profile of the restoration and a tight fit of the sectional matrix, a gingivectomy was performed with an electrical surgical knife (Fig. 5). The main advantages of a diathermic cut are instant tissue coagulation and haemostasis.⁹

In accordance with the European Society of Endodontology’s guidelines on the management of deep caries,¹⁰ the deepest part of the cavity was cleaned under full dental dam isolation (Nic Tone, MDC Dental; Fig. 6). Carious tissue excavation was carried out using round burs and then the enamel and dentine were air abraded with 50 μm aluminium oxide (MicroEtcher IIA, Danville Materials). Multiple cracks, penetrating through the enamel and partially the dentine, had occurred within the mesial and palatal walls. The presence of cracks crossing the amelodentinal junction is an absolute indication for cuspal coverage.^8, 11

Appropriate dental dam isolation is essential in adhesive dentistry. Beyond the obvious advantage of a clean operation field uncontaminated by saliva and moisture, the dental dam contributes to keeping periodontal tissue at a distance from the respective tooth. In order to ensure both maximum retraction and sufficient space to work, the dental dam was inverted (introduced to the gingival sulcus) and stabilised using PTFE tape (Fig. 7). The mesial wall was restored using a blue Composi-Tight 3D Fusion matrix ring (Garrison Dental Solutions) and a medium standard sectional contoured metal matrix (TOR VM; Fig. 8).

Owing to its extensiveness and shape, the distal wall was more difficult to restore. The first attempt to adapt an elongated sectional contoured metal matrix (TOR VM) and a green Composi-Tight 3D Fusion matrix ring ended in failure (Fig. 9). The matrix was changed for a longer and more curved option (Fig. 10). The ring was replaced by a smaller Palodent V3 ring (Dentsply Sirona; Fig. 11). Owing to the depth of the carious lesion, an antibacterial adhesive system was used (CLEARFIL SE Protect, Kuraray Noritake Dental). It contains the MDPB monomer, which offers an antibacterial effect that lasts even after the hybrid layer formation.^12–14 Furthermore, the fluoride included in the bond liquid intensifies the cariostatic mechanism of CLEARFIL SE Protect and supports the formation of “super dentine”.¹⁵

The initial polishing was performed with the dental dam still in place. The excess composite resin was removed with the aid of abrasive discs, diamond burs and a Brownie polisher (BAL, Nevadent). Pre-polishing and high-shine polishing were executed with TWIST DIA for Composite (Kuraray Europe) supported by a goat hair brush (Micerium; Figs. 16 & 17).

Conclusion

As a result of decades of improvements primarily with regard to filler density and polishability, modern dental composites now offer great gloss retention and favourable wear properties. In addition, polymerisation shrinkage has been decreased owing to the integration of nano-hybrid filler technology. These features allow the restoration of biomechanically compromised teeth using a direct restoration technique.

Direct overlays are a suitable alternative to a conventional indirect restoration in many situations.^18, 19 According to research, the advantages of direct restorations with cuspal coverage include minimal tooth preparation, vital pulp-oriented treatment, the possibility of treating patients in a single appointment and a potentially reduced cost of treatment.^18–20 However, it should be emphasised that the technique presented in this article requires advanced restorative skills to be properly implemented.