Comparative evaluation of internal fit and marginal gap of endocrowns using lithium disilicate and polyether ether ketone materials - an in vitro study

Abstract

Background The aim of the study was to investigate the effect of material and occlusal preparation design on the internal fit and marginal gap of endocrowns made of Polyether ether ketone (PEEK) and lithium disilicate. Methods 32 endocrowns were fabricated on prepared mandibular molars and divided into two groups (n = 16) according to the material. Group L: lithium disilicate and Group P: PEEK. Each group was further subdivided into two subgroups (n = 8) according to the occlusal preparation design: full occlusal coverage (LF and PF) and partial occlusal coverage (LP and PP). Samples were analyzed using microcomputed tomography (µCT) with a voxel size of 6 μm to evaluate internal fit, and an optical microscope was used to evaluate the marginal gap. Data were collected, tabulated, and statistically analyzed. Numerical data were described as mean and standard deviation and compared using the ANOVA test. The level of significance was set at α P ≤ 0.05. Results All groups’ internal fit and marginal gaps values were within the acceptable clinical range. However, the lithium disilicates group recorded statistically significantly higher mean internal gap values than the PEEK groups. Regardless of the material, the difference between the two occlusal designs was not statistically significant in both internal fit and marginal gap records. Conclusion Within the limitations of this study, PEEK endocrown restorations revealed better internal fit and marginal gap than lithium disilicate endocrown restorations. The marginal and internal fit of both lithium disilicate and PEEK endocrown restorations were within the clinically acceptable range. The occlusal preparation design had no influence on the internal fit and marginal gap of the endocrown restoration.

A Comparative Analysis of Marginal Adaptation Values between Lithium Disilicate Glass Ceramics and Zirconia-Reinforced Lithium Silicate Endocrowns: A Systematic Review of In Vitro Studies

“…All included studies were in vitro studies [ 12 – 28 ]. The highest number of publications, 7 studies (41%), was from the year 2023 [ 12 – 15 , 19 , 20 , 22 ], followed by years between 2020 and 2022, with 6 studies (35%) [ 20 , 21 , 25 – 28 ]. Fourteen (76%) studies reported using natural teeth [ 12 – 15 , 17 – 23 , 25 – 27 ], 12 studies (71%) were for mandibular arches [ 13 – 17 , 19 – 20 , 22 – 25 , 27 ], and 11 studies (65%) were for molars [ 13 – 16 , 19 , 22 – 25 , 27 , 28 ].…”

“…The highest number of publications, 7 studies (41%), was from the year 2023 [ 12 – 15 , 19 , 20 , 22 ], followed by years between 2020 and 2022, with 6 studies (35%) [ 20 , 21 , 25 – 28 ]. Fourteen (76%) studies reported using natural teeth [ 12 – 15 , 17 – 23 , 25 – 27 ], 12 studies (71%) were for mandibular arches [ 13 – 17 , 19 – 20 , 22 – 25 , 27 ], and 11 studies (65%) were for molars [ 13 – 16 , 19 , 22 – 25 , 27 , 28 ]. LDGC and zirconia were the most common all-ceramic materials used for endocrown constructions, with 35% and 30%, respectively, and either alone or in comparisons with other all-ceramic materials.…”

“…Some in vitro studies documented equal or slightly higher marginal gap values, as documented by Jalali et al, with 160 μm for zirconia CAD/DAM [ 14 ], and by Shin et al, with 138 μm for LDGC CAD/CAM [ 23 ]. An equal value of marginal adaptation or slightly lower values were obvious in laboratory studies conducted by Sağlam et al for both LDGC and zirconia CAD/CAM [ 27 ], LDGC endocrowns constructed with CAD/CAM or heat-press systems [ 25 ], and LDGC manufactured by CAD/CAM [ 22 ]. Most of the studies recorded values ranging from 30 to 70 μm, as shown in Table 1 .…”

“…Marginal bonding areas can be evaluated by different methods. Because it is a nondestructive and repeatable technique, stereomicroscope [ 12 – 18 ] followed by direct digital microscopic [ 19 – 21 ] examination of the marginal area is the most widely used method to measure the endocrown marginal adaption in different bonding areas, while micro-computed topography [ 22 – 25 ], scanning electron microscopy (SEM) [ 26 , 27 ], and other [ 28 ] systems can be used for endocrown marginal gap measurements.…”

“…Various ceramic systems are used for endocrown fabrications, such as feldspathic ceramics [ 26 , 27 ], lithium disilicate glass ceramics (LDGC) [ 13 , 15 – 19 , 22 , 23 , 25 ], and different types of zirconia [ 13 , 14 , 21 ], which have high mechanical strength and can be acid-etched. Zirconia and LDGC are considered the best choices owing to their mechanical and aesthetic features, including good anti-abrasion, anti-aging, and anti-corrosion properties, translucency, and biocompatibility with natural teeth.…”