English

Abstract

BACKGROUND Inadequate marginal fit of fixed restorations leads to plaque accumulation, recurrent caries and periodontal problems. The purpose of this experimental study is to evaluate and compare the marginal fit/gap of computer-aided design and computeraided manufacturing (CAD/CAM) fabricated zirconia copings and zirconia full contoured monolith crowns fabricated on type IV gypsum die having a definite cement spacer thickness of 0.05mm. METHODS This is an in-vitro experimental study carried out from November 2018 to November 2019. A master stainless steel die was used to make 52 type IV die stone models which were randomly divided into 2 groups of 26 samples each. Group 1: zirconia copings and group 2: zirconia monolith full contoured crowns. These restotations were fabricated using CAD/CAM. The marginal gap of each zirconia copings and zirconia full contoured crowns was assessed using scanning electron microscopic analysis on four different pre-marked points (GEMINI SEM 500; ZEISS). Observations were tabulated and analyzed statistically. Independent t-test was used to compare the measurements between zirconia copings & zirconia monolith crowns. RESULTS The least marginal gap observed was for group 2 (zirconia full contoured crown) with a mean value of 29.88 ± 9.16 μm while that of group1 (zirconia coping) was 73.64 ± 28.13 μm. There was a statistically significant difference in the measurements between zirconia copings and zirconia full contoured monolith crowns (P - value < 0.001). There was statistically significant difference in each side of zirconia monolith crowns when compared to the corresponding side of zirconia copings (P - Value < 0.001). CONCLUSIONS CAD/CAM milled full contoured zirconia crowns showed least marginal discrepancy when compared to zirconia copings. All samples had marginal gap within the clinically acceptable range of 120 μm. KEY WORDS Monolith, Zirconia Crowns, Zirconia Copings, Full Contoured Crowns, CAD-CAM