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 construc- ted and divided into 4 groups according to the type of restorations: full coverage, inlay-shaped (occluso-pro- ximal inlay + proximal box), tub-shaped (occluso-pro- ximal 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-shap- ed 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 signifi-cant difference than all inlay retained FPDs designs tested. The inlay-shaped design was significant dif-ference than the other two inlay retained FPDs de-signs. Conclusions: There was no significant differ- ence between full coverage FPDs, tub-shaped & pro- ximal box shaped inlay retained FPDs as regard ver- tical marginal discrepancies. While, the inlay-haped design showed the highest vertical marginal discrep- ancies. The premolar & molar retainers for the same type of restorations showed no difference in vertical marginal discrepancies. All measured vertical mar- ginal discrepancies were in the range of clinical ac- ceptance. The full coverage FPDs recorded higher retentive strengths than all inlay retained FPDs de- signs tested. The inlay-shaped design recorded the highest retentive strengths among the three inlay re- tained FPDs designs. There was no difference as re- gard retentive strengths between tub-shaped & pro- ximal box shaped inlay retained FPDs.
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