Clinical evaluation of dental restorative materials - Part III: FDI criteria

In 2007, recommendations for conducting clinical trials approved by the FDI were published in several peer-reviewed journals. These recommendations not only addressed designing protocols for clinical trials but also challenged the Ryge criteria with an in-depth discussion of  clinical evaluation criteria and suggested a new approach in clinical evaluation of dental restorative materials and operative techniques.

In August 2010, an update of the "FDI clinical criteria for the evaluation of direct and indirect restorations" was published  by Hickel et al. in the Journal of Adhesive Dentistry and Clinical Oral Investigations. A lot of clinical examples were presented in the paper to illustrate various ratings.

The new FDI criteria set a different background for the evaluation of dental restorations by introducing 3 groups of criteria: esthetic, functional and biological. Each of these groups has subgroups with 16 evaluation criteria in total. These are:

Esthetic criteria

1. Surface luster
2. Staining: (a) surface and (b) margin
3. Color match and translucency
4. Esthetic anatomical form

Functional criteria

1. Fracture of material and retention
2. Marginal adaptation
3. Occlusal contour and wear 
4. Approximal anatomical form: (a) contact point and (b) contour
5. Radiographic examination, where applicable
6. Patient's view

Biological criteria

1. Postoperative sensitivity and tooth vitality
2. Recurrence of caries, erosion, abfraction
3. Tooth integrity
4. Periodontal response
5. Adjacent mucosa
6. Oral and general health

For all three groups, the following gradings are used for evaluation:

1. Clinically excellent/very good
2. Clinically good
3. Clinically sufficient/satisfactory
4. Clinically unsatisfactory
5. Clinically poor

When judging a dental restoration using the FDI criteria, the score for each group is dictated by the most severe grading among the criteria for that particular group. Similarly, the overall score is determined by the worst grading among the groups. For example, if the functional criteria are unacceptable, the overall score is unacceptable. Detailed description of each grading is given in the previously mentioned paper: "FDI World Dental Federation - Clinical Criteria for the evaluation of direct and indirect restorations".

It is not mandatory to apply all of the FDI criteria in each study. In each particular study, the examiners should determine which criteria match their intended purposes best.

Gradings for the FDI criteria are substantially more detailed and sensitive than the Cvar and Ryge criteria and their modifications suggested by other authors. These detailed gradings challenge the training and calibration procedure of the examiners. To allow an easier and more efficient training, reduced variability in judgment and greater coherence in multi-centric studies, an online calibration system was established at www.e-calib.info. It is emphasized by the authors of the FDI criteria that the e-calibration system does not replace the clinical setting but shortens clinical training significantly.

Beside their use in clinical trials, the FDI criteria are recommended for quality assessment of restorations by general dental practitioners in their everyday practice and as guidelines whether or not a restoration needs refurbishment, repair or replacement. Refurbishment is a minimal intervention such as polishing or contouring when no additional material is placed. Repair is a minimal intervention which requires additional material to be placed with or without a minimal preparation in the restoration or dental tissues.

Clinical investigators are strongly advised to use the new FDI criteria when designing and conducting clinical trials. However, the criteria are "not indefinitely fixed and defined" so investigators are asked for feedback and encouraged to contribute to the e-calib database with high quality images of clinical cases.

References

Hickel R, Peschke A, Tyas M, Mjör I, Bayne S, Peters M, Hiller KA, Randall R, Vanherle G, Heintze SD. FDI World Dental Federation - clinical criteria for the evaluation of direct and indirect restorations. Update and clinical examples. J Adhes Dent. 2010 Aug;12(4):259-72. doi: 10.3290/j.jad.a19262.

Hickel R, Roulet JF, Bayne S, Heintze SD, Mjör IA, Peters M, Rousson V, Randall R, Schmalz G, Tyas M, Vanherle G. Recommendations for conducting controlled clinical studies of dental restorative materials. Science Committee Project 2/98--FDI World Dental Federation study design (Part I) and criteria for evaluation (Part II) of direct and indirect restorations including onlays and partial crowns. J Adhes Dent. 2007;9 Suppl 1:121-47.