Restoration of endodontically treated maxillary central incisors with class III defects is a challenging procedures because the choice of which rehabilitation to choose depends on the amount of structure remaining. The aim is to give new functionality to the element but also to obtain a good aesthetic result, since we have to deal with an element of the frontal sector. Moreover, endodontically treated anterior teeth were found to have an high risk of biomechanical failure due to shear forces.
We can choose between different kind of restorations: direct restoration with composite; direct restoration with endodontic glass-fiber post and composite; veener restoration; veener restoration with endodontic glass-fiber post; crown restoration; crown restoration with endodontic glass-fiber post.
Which is the best solution?
Von Stein-Lausnitz et al. in their study published in the Journal of Adhesive Dentistry tried to give an answer.
MATERIALS AND METHODS
Seventy-two extracted human maxillary central incisors were endodontically treated and bi-proximal Class III cavities were prepared. They were randomly allocated to six groups (n = 12): direct restoration with composite (group C); direct restoration with composite and additional glass-fiber post (group CP); ceramic veneer restoration (group V); ceramic veneer restoration with endodontic glass-fiber post (group VP); ceramic crown restoration (group Cr); ceramic crown restoration and additional glass-fiber post (group CrP). They were exposed to thermomechanical loading (TML: 1.2 million cycles, 1 to 50 N; 6000 thermal cycles between 5°C and 55°C for 1 min each), and subsequently linearly loaded until failure (Fmax [N]) at an angle of 135° and 3 mm below the incisal edge on the palatal side. Statistical tests were performed using the Kruskall-Wallis and Mann-Whitney U-Test.
During dynamic loading by TML, one fracture of the incisale edge occurred in group C; one loss of composite restoration in group CP, and one crown fracture in group CrP.
Subsequent linear loading resulted in mean fracture load values [N] of:
The Kruskal-Wallis test showed significant differences of load capacity between groups (p < 0.05).
Mann-Whitney U-test revealed significantly lower maximum fracture load values of group C compared to group V (p = 0.014), after Bonferroni-Holm correction. Non-restorable root fracture with fracture lines more than 2mm below CEJ was the most frequent type of failure in all groups (68%).
Endodontically treated maxillary central incisors with Class III defects directly restored with composite are as loadable as indirect crown restorations. Compared to full-coverage restorations, less invasive veneers appear to be more beneficial. Additional placement of glass-fiber posts shows no positive effect.
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