17 June 2020

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Survival rate of Deep margin elevation for indirect partial restorations

Simona Chirico

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Indirect partial restorations are a good option in case of medium and large sized cavities in posterior teeth, because they can guarantee not only aesthetics, but above all protection to the portion of residual dental tissue. Often these cavities, due to the presence of carious lesion, can extend up to the inside of the gingival margin, causing difficulty in isolating the dental element. To resolve this problem, a clinical approach could be the deep margin elevation. This technique allows to relocate the cervical margin of a subgingival preparation supragingivally, using a resin composite material. Subsequently, indirect ceramic or composite restorations can be luted in an isolated workfield using rubberdam. Furthermore, the deep margin elevation makes impression taking and luting of indirect restorations easier and more predictable.
There are so many in vitro and in vivo studies discussing about this technique, but which is the survival rate of indirect partial restoration with deep margin relocations? Bresser and his team with their study, published on Journal of Dentistry, tried to answer to this question. 

Materials and Methods
Patients who were treated in a private dental practice by one restorative dentist between 2007 and 2016 and received indirect restorations in combination with deep margin elevation, were eligible for inclusion. Deep margin elevation was indicated in situations with deep subgingival margins that would complicate impression taking and adhesive luting of the indirect restoration because a dry working field would be difficult to obtain. 
At least, a total of 197 indirect restorations in 120 patients could be included. Survival rates was performed using the modified United States Public Health Service (USPHS) criteria using Chi-square tests.

Results
The survival rate was 95.9% up to 12 years, with an average evaluation time of 57.7 months.
8 restorations were considered as absolute failures, due to: secondary caries, fracture of the restoration/tooth, debonding of the indirect restoration, root caries, severe periodontal breakdown, pulpal necrosis.
Some complications was recorded during the evaluation:
- indirect composite restorations showed more degradation compared to ceramic restorations;
- more wear of the antagonist was observed when teeth were opposed to ceramic restorations;
- endodontic treatment negatively impacted the occurrence of fracture of restorations and teeth.

Conclusions
With the limitation of this study, we can conclude that indirect partial restorations with deep margin elevation have a good survival rate and this technique could be used in all situations where it is required.

For additional information: Up to 12 years clinical evaluation of 197 partial indirect restorations with deep margin elevation in the posterior region.