Fig.1
The described case is characterized by the presence of an incongruous amalgam restoration with evident signs of leakage.

Fig.2
The X-ray shows material fracture at the occlusal level and chipping of the cervical enamel.

Fig.3
First, the field is isolated placing the rubber dam.

Fig.4
The old restoration is removed, and the carious tissue thoroughly cleaned. The residual position of the cervical step below the free gingival margin makes it impossible to adequately isolate the field and perform the restorative phases.

Fig.5
After removing the rubber dam.

Fig.6
The margin is surgically exposed.

Fig.7
The osteoresective surgery aims to restore the correct biologic width (12;13) by positioning the bone crest approximately 2.5 mm apical to the cleaned cervical step.
Sutures are performed using EPTFE.

Fig.8
The proposed technique involves the application of a hydrophilic cellulose-based paste.

Fig.9
This paste acts as a mechanical barrier to improve the seal provided by the immediate postoperative placement of the rubber dam.

Fig.10
Considering the extent of the cavity, the sectional matrix may collapse due to lack of support from the axial walls of the interproximal box, making it difficult to construct an adequate contact surface. Capillary bleeding may also occur.

Fig.11
To overcome this issue, a preformed circumferential matrix with the assistance of a separating ring (Garrison 3D) and a compressive interdental wedge is preferred. This allows adherence to the preparation perimeter on both the cervical step and the axial walls of the box, enabling the construction of a congruent contact area.

Fig.12
The adhesive phase is performed using a self-etch adhesive and enamel pre-conditioning. A maximum 1mm thick layer of flowable composite is applied to seal the dentin at the cervical level.

Fig.13
A medium-high shade composite mass (A2 Venus Pearl – Kulzer) is used to build the proximal wall up to the marginal ridge in a single step.

Fig.14
The dentin body is then stratified in multiple increments using a chromatic mass (Venus Pearl A5 – Kulzer), and the occlusal morphology is completed with one or more increments of enamel (Venus P CL and AM – Kulzer), shaped to achieve proper occlusal anatomy. After polymerization, the grooves are characterized by selective application of intensive stain liquid chocolate.

Fig.15
When the cavity is very large, the force exerted by the matrix may deform the morphology of the interproximal transition areas, resulting in an undesirable profile. This can be corrected by placing a second transparent polycarbonate matrix with a wedge.

Fig.16
Which, after adequate adhesive treatment, contains a sufficient amount of composite.

Fig.17
The corrected restoration, with a more appropriate contour and emergence profile.

Fig.18
After final polymerization under glycerin gel, finishing is performed using fine-grit diamond burs, abrasive discs, Supra Brown to Grey rubber points at 7500 g/m with water spray, and finally, synthetic and self-polishing brushes impregnated with silica carbide.

Fig.19
Radiographic check confirms proper cervical seal and emergence profile.

Fig.20
The 50-day follow-up shows adequate and fast healing of the marginal tissues.

Conclusions

The combined surgical-restorative approach in a single session allows for effective and predictable clinical management of extensive cavities with subgingival margins. Performing immediate post- or intra-operative direct restoration offers the following advantages:

• Clinical Benefits: Surgical exposure of the margin and/or osseous recontouring (with restoration of biologic width when violated) enables effective isolation with rubber dam and facilitates subsequent adhesive procedures, placement of matrices, interproximal wedges, and retainer rings, as well as refinement and interproximal polishing.
• Biological Benefits: Post-surgical healing occurs under ideal conditions, facilitated by consistent and adequate interproximal contact points, correct emergence profiles, and refined and polished surfaces, resulting in reduced morbidity and faster aesthetic and functional restoration (1;2;12;14). The extent of osseous recontouring can be minimized when combined with coronal relocation of the cervical margin using composite increment (14;15;16). The direct restorative approach allows for greater preservation of healthy residual tissues compared to indirect techniques and ensures adherence to the fundamental principle of immediate dentin sealing (IDS), thereby improving the reliability of adhesive performance (13).
• Ergonomic and Economic Benefits: Performing the procedure in a single session optimizes operative time by eliminating interim provisional restoration phases and avoids laboratory costs, thereby reducing overall costs for the patient. This makes the approach appealing, dynamic, and efficient (1).

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