Evaluation of marginal and internal fit of posterior monolithic resin nano ceramic crowns

Ceramic, resin nanoceramic, lithium disilicate, CAD-CAM, occlusal thickness, accuracy, fit, gap, marginal, internal

Prof. Mirza Rustum Baig1*
([email protected])
Department of Restorative Sciences,
College of Dentistry, Kuwait University
ORCID ID 0000-0002-2343-3787
Scopus ID 22939891100

Dr. Fajer Abdulaziz alnajjar2
([email protected])
Ministry of Health Kuwait
Scopus ID59233977700

Dr. Arwa Jamal Alloughani3
([email protected])
Ministry of Health Kuwait
Scopus ID 59233635000

Dr. Ahmad AlSahli4
([email protected])Department
of General Dental Practice,College of
Dentistry, Kuwait University
ORCID ID 0000-0001-5981-5819
Scopus ID 59126682700

Received: 01.01.2026
Revised: 21.01.2026
Accepted: 25.02.2026

European Journal of Prosthodontics and Restorative Dentistry (2026) 34(2), 111–120

Evaluation of marginal and
internal fit of posterior
monolithic resin nanoceramic
crowns
-----------------------------------------------------------------------ABSTRACT
Purpose: To assess the fit accuracy of resin nanoceramic (RNC) crowns in
comparison with lithium disilicate (LDS) crowns, in terms of marginal and
internal gap, and to investigate the effect of crown occlusal thickness (OT) on
the fit, for both materials.
Materials and Methods: Forty stone dies were derived from a master metal die,
with 20 each for the 0.5mm and 0.75mm minimum OT groups. The stone dies
were digitized to design and mill the ceramic crowns, 10 each for the 4
material–OT combinations (n=10). All the crowns were seated on the master
metal die using silicone fit checker. The silicone records were then fixed and
sectioned. Marginal gaps were assessed at 6 locations, and internal gaps were
measured at 48 points, on the silicone record sections, for each crown, using a
stereomicroscope-based image analysis system. The effects of the material and
occlusal thickness on the crown fit were analyzed with 2-way ANOVA and
Bonferroni post-hoc tests (α=.05).
Results: Mean marginal and internal gaps for RNC crowns were 73±16µm and
157±7µm, and 84±19µm and 155±12µm for the LDS crowns, respectively.
Two-way ANOVA showed significant marginal gap differences between the 2
materials, and between the OTs (P<.05). However, internal gap differences
were not significant (P>.05), although internal gaps differed significantly
according to occlusal thickness (P<.01).
Conclusions: The marginal and internal gaps of RNC and LDS crowns were
found to be within acceptable limits. Occlusal thickness significantly affected
the internal gap of both materials.

Resin nanoceramics (RNC) are currently used in the computer-aided design and computer-aided-manufacturing (CAD-CAM) production of fixed dental prostheses, including crowns.1-3 RNCs are hybrid materials available as monolithic machinable ceramic blocks, composed of nano particles (silica, zirconia and/or barium) in a composite resin matrix.4,5 The RNCs are purported to have better mechanical properties compared with the conventional glass ceramics, including less abrasiveness, high flexural strength, and intra-oral reparability, in addition to superior marginal integrity, no sintering or firing requirement, and ease of polish.5-8 Marginal fidelity is a vital criterion used to ascertain the clinical acceptability of indirect restorations at placement and at follow-up examinations.9,10 Excessive marginal discrepancies may potentially lead to periodontal disease, cement dissolution, recurrent caries, and even pulpal inflammation.11-15 Different factors, including the type of ceramic,16,17 cement space setting,18 abutment preparation design,19 and CAD-CAM milling system parameters,20,21 have been shown to influence the borderline and core fit aspects of fixed restorations. Furthermore, inadequate internal adaptation and luting cement thickness may affect the fracture resistance of ceramic crowns.20,22 Previous systematic reviews 22,23 and related guidelines24 have suggested 80-120 µm as a clinically appropriate range of borderline gaps for ceramic CAD/CAM •••••••••••••••••••••••••••••••• ejprd.org - Published by Riset Publishing Services LLC

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