Association of fit of partial denture metal framework with various framework design features using alginate as a final impression material: A prospective clinical study.

Objectives: To assess the fit of PRDP frameworks fabricated using alginate as a final impression material in metal stock trays, in terms of number of fabricated frameworks needed until realization of clinically adequate fit. Also, any association of framework fit achieved with its design features, namely major connector design, and numbers of guide plates and occlusal/incisal rests was investigated.

Methods: 147 partially dentate patients were provided with Co-Cr PRDPs, in single or both arches, by undergraduate dental students. Final impressions were made with alginate in metal stock trays. At metal framework try-in, clinical examinations were carried out by two prosthodontists and relevant information noted with regard to proper fit. The relationship between three PRDP design features and number of frameworks that needed to be made in each case to achieve satisfactory fit was determined using factorial analysis of variance (ANOVA) (α = 0.05).

Results: 86% (148) of the 173 frameworks fabricated were found to be clinically satisfactory at the first try-in visit (with or without any chairside adjustment). The remaining 14% (25) required new impressions for re-fabrication and passed at the second attempt. None of the examined design features were significantly associated with the number of construction attempts needed, for all 173 arches, or when maxillary and mandibular arches were considered independently (p >  0.05).

Conclusions: PRDP design features were not associated with the level of accuracy of fit achieved.

Clinical Significance: Alginate in metal stock trays seems to be acceptable for final impressions of all types of Co-Cr PRDP designs with just 1 in 7 castings not fitting after chairside adjustment.