Mechanical Strength and Wear of Dental Glass-Ionomer and Resin Composites Affected by Porosity and Chemical Composition

Abstract

The main aim of this study was to evaluate the influence of porosity, microstructure, and chemical composition on the wear and compressive strength of dental glass-ionomer or resin composite. Cylindrical samples (6 9 4 mm) were prepared from a nano-hybrid resin composite (Grandio Ò SO/RC, VOCO), a resin-modified glass ionomer (Vitremer TM /VI, 3 M-ESPE) and a conventional glass ionomer (Ionofil Ò Molar/CO, VOCO). Porosity and topography of the materials were evaluated by optical and scanning electron microscopy (SEM). Roughness was evaluated by R a and R t parameters at 0.1 mm/s under cutoff of 0.8 mm. Then, compressive tests were performed at 1 mm/min. Wear tests were carried out at 20 N, 2.5 mm of displacement, at 1 Hz for 90 min in artificial saliva solution. The results were statistically analyzed with a one-way ANOVA and Tukey's test (p \ 0.05). Resin composite revealed a significantly lower porosity (1.21 ± 0.20 %) than glass-ionomer restoratives (5.69-7.54 %) as well as lower values of R a and R t roughness (p \ 0.05). Also, resin composite showed significantly higher values of mechanical strength (334 ± 15.9 MPa) compared to conventional (78.78 ± 13.30 MPa) or modified glass ionomer (169.50 ± 20.98 MPa) (p \ 0.05). For maximal depth of wear, resin composite also showed significantly lower values than glass ionomer (p \ 0.05). Homogeneous wear morphology was noticed by SEM analyses on glass ionomers in opposition to resin composite. Glass ionomers showed a poor mechanical behavior associated to a high porosity and wear rate when compared to resin composite.

On the synthesis and characterization of β-tricalcium phosphate scaffolds coated with collagen or poly (D, L-lactic acid) for alveolar bone augmentation

“…The compressive force curves were recorded using the Trapezium (Shimadzu Corporation, Tokyo, Japan) software and the compressive strength values were calculated using the equation F/w 2 , whereas F is the maximum load at fracture and w the cross-section area of the specimen. [ 21 ]…”

Enhancing the Mechanical Properties of Glass-Ionomer Dental Cements: A Review

“…Other low values of compressive strength have been reported for conventional glass-ionomers. For example, the material Ionofil Molar (VOCO, Cuxhaven, Germany) was reported to have a compressive strength of 78.78 MPa, well below that of the resin-modified materials Vitremer (3M-ESPE, Seefeld, Germany), which had a compressive strength of 169.50 MPa [37]. While it is interesting to observe how high the compressive strength of a resin-modified glass-ionomer can be, the value for the conventional glass-ionomer must be questioned.…”

Microtomographic Analysis of Resin Composite Core Material Porosity

“…Porosity has been suggested to degrade resin composite materials’ mechanical properties via many mechanisms 13,14,27,33‐41 . Depending on the remaining tooth structure and preparation of the ferrule design, a resin composite core material plays a vital role in the restoration of root‐filled teeth managing the applied functional forces applied to the remaining tooth structure 42,45,46,55‐59,65 .…”

“…Regardless of chosen technique, resin material porosity is a recognized feature that has been proposed to be due to resin manufacturing processes 13 and filler size/fraction differences, 14‐20 but is mostly accredited to clinical manipulation 21‐32 . Resin composite porosity may significantly degrade restoration mechanical and esthetic properties, 33‐37 provide stress concentration points to facilitate internal crack formation/propagation, 14,38‐40 and enhance marginal leakage and discoloration 13 . The potential for internal voids to serve as water reservoirs may lead to increased matrix plasticization, 34,41 that may also contribute to increased wear 27,36 .…”

“…Resin composite porosity may significantly degrade restoration mechanical and esthetic properties, 33‐37 provide stress concentration points to facilitate internal crack formation/propagation, 14,38‐40 and enhance marginal leakage and discoloration 13 . The potential for internal voids to serve as water reservoirs may lead to increased matrix plasticization, 34,41 that may also contribute to increased wear 27,36 . Overall, porosity's role possibly contributing to future failure of many dental materials may be not considered by many clinicians 42‐44 .…”