Pit and fissure nanocomposite sealants reinforced with organically modified montmorillonite: A study of their mechanical properties, surface roughness and color stability

Abstract

The aim of the present work was to investigate the effect of the different organically modified nanoclays on clinically significant properties of new synthesized dental pit and fissure nanocomposite sealants. Their morphological characteristics were examined by means of X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). A universal testing machine was used to conduct the flexural and compression tests. Surface roughness measurements were taken by using a 3D-optical profilometer. Color changes after aging in black tea were determined by recording UV-visible spectra. XRD plots depicted possible structures governed by intercalated regions along with some "tactoids" nanoparticles. SEM images revealed a better dispersion for the methacrylated clay nanofiller. Flexural modulus and microhardness were found to be higher for sealants reinforced with such polymerizable nanoclays. These specific nanocomposites yielded smoother surfaces, as well as clinically accepted color changes even after 1 week aging in black tea.

Effect of surface sealants on color stability of different resin composites

“…Similar inorganic filler concentrations of the composites (FU: 78.5 wt%, 63.5 vol%; CT: 76 wt%, 65 vol%; CM: 78 wt%, 66 vol%) could not be the explanation of this difference. However, the type of the fillers (silica, zirconia and silica/ zirconia cluster fillers), as well as the size of the fillers in FU composite might have influenced the color stability [9,22]. Another possible explanation is that triethyleneglycol dimethacrylate (TEGDMA) in FU might have enhanced the surface hardness, elastic modulus and the degree of polymerization, thus contributed to better resistance against discoloration [9,38].…”

“…However, the type of the fillers (silica, zirconia and silica/ zirconia cluster fillers), as well as the size of the fillers in FU composite might have influenced the color stability [9,22]. Another possible explanation is that triethyleneglycol dimethacrylate (TEGDMA) in FU might have enhanced the surface hardness, elastic modulus and the degree of polymerization, thus contributed to better resistance against discoloration [9,38]. On the other hand, TEGDMA containing FU might have had the disadvantage of being significantly sensitive to discoloration when immersed in hot coffee compared to cold [31].…”

“…Polishability of the composite materials directly effects the optical properties, whereas also influencing the surface roughness of the restoration as well [8]. A smooth restoration surface reduces plaque accumulation, thus minimizing the possibility of periodontal diseases and caries process [9]. However, not only the material-related factors but also poor oral hygiene, smoking habits, eating habits of the patient may affect the discoloration of the restorations [10].…”

“…Surface covering agents (surface sealants) have been developed to reduce the discoloration capacity of the RBCs [9]. Surface sealants are low-viscosity, resinbased materials covering the surface of the composite restorations by penetrating through micro-structural defects [12].…”

Colorimetric Assessment of Surface Sealants for Discoloration of a Nanofilled Resin Composite

“…Type, shape, size, and amount of the inorganic filler particles may alter the physical properties of the RBC material. Also effective polishing using proper polishing materials is essential to achieve a smooth restoration surface, thereby, inhibiting the plaque accumulation and the caries process (5). Whereas, patient related factors (i.e., systemic diseases, oral hygiene, diet, and smoking habits) may also influence the long-term color stability of RBC restorations.…”