Vertical marginal gap & retention of ceramic full coverage & inlay retained ceramic fixed partial dentures

Objectives: A comparison study between ceramic full coverage FPDs & 3 designs of ceramic inlay retained FPDs regarding vertical marginal gap & retention. Materials & Methods: Twenty samples were constructed and divided into 4 groups according to the type of restorations: full coverage, inlay-shaped (occluso-proximal inlay + proximal box), tub-shaped (occluso-proximal inlay), and proximal box-shaped FPDs. All samples were subjected to a vertical marginal gap measurements followed by a retention test. Results: The vertical marginal gap data showed no significant difference between full coverage FPDs, the tub-shaped inlay retained FPDs and the proximal box-shaped inlay retained FPDs. While there was a difference between these three designs and the inlay retained FPDs. Regarding retention, the full coverage FPDs recorded higher retentive strengths and was significant difference than all inlay retained FPDs designs tested. The inlay-shaped design was significant difference than the other two inlay retained FPDs designs. Conclusions: There was no significant difference between full coverage FPDs, tub-shaped & proximal box shaped inlay retained FPDs as regard vertical marginal discrepancies. While, the inlay-haped design showed the highest vertical marginal discrepancies. The premolar & molar retainers for the same type of restorations showed no difference in vertical marginal discrepancies. All measured vertical marginal discrepancies were in the range of clinical acceptance. The full coverage FPDs recorded higher retentive strengths than all inlay retained FPDs designs tested. The inlay-shaped design recorded the highest retentive strengths among the three inlay retained FPDs designs. There was no difference as regard retentive strengths between tub-shaped & proximal box shaped inlay retained FPDs.