Abstract
Objective: The aim of this study was to evaluate the influence of different base materials on
fracture strength of mesio-occlusal-distal (MOD) composite restorations. Materials and Methods: Forty-eight extracted, intact maxillary molar teeth with standardized, deep MOD cavities
were randomly assigned into four groups according to the base material placed: Control
group (CO); no base material, SDR group; bulk-fill flowable composite, CGIC group;
chemically curing glass ionomer cement (GIC), and RGIC group; light curing resin reinforced
GIC. All the specimens were then restored with a nanocomposite (CeramX Duo/Dentsply)
in combination with etch and rinse adhesive following the manufacturer’s instructions.
After aging fracture, strength of the specimens was tested by the application of a
ramped oblique load to the buccal cusp in a universal testing machine. Mean fracture
strength values for each group were calculated and compared using one-way ANOVA (P = 0.05). Fracture patterns of the specimens were also evaluated. Results: The mean loads necessary to fracture the samples were as follows: control: 819.22
± 253.65; SDR: 694.46 ± 266. 55; CGIC: 559.15 ± 277.34; RGIC 861.87 ± 277.28: N. The
control and RGIC groups showed significantly higher fracture strength than CGIC and
SDR groups (P < 0.05). Although the mean fracture strength value of SDR group was higher than that
of CGIC group, the difference between these groups was not statistically significant
(P > 0.05). Most frequently observed fracture patterns were adhesive (58.3%) in CO,
cohesive (50%) in SDR group, cohesive (83.3%) in CGIC group, and mixed (41.7%) in
RGIC group. Conclusions: Resin-modified glass-ionomer cement as a base material or restoration of the tooth
only with composite resin resulted in higher fracture strength than composite resin
restoration with a conventional glass ionomer base or a flowable bulk-fill material.
Fracture pattern distributions diversed according to the base material placed under
composite restoration.
Keywords
Bulk-fill - composite - fracture strength - glass ionomer cement