Evaluation of 12-hour in situ bacterial colonization on smooth restorative material surfaces

The Effect of Plaque Detectors on the Color Stability of Two Types of Restorative Materials

OBJECTIVE

To investigate the color stability of a one-shade resin-based composite material (RC) and a glass-ionomer cement (GIC) after staining with plaque detectors (PDs) with different formulations and delivery forms.

MATERIALS AND METHODS

Rectangular-shaped specimens (7 × 3 × 2 mm) were produced with RC (Venus Diamond One, Kulzer) and GIC (Fujy IX GP, GC) (n = 30). Further, the following PDs were used on the specimens: (1) tablets (T; Plaq-Search, TePe); (2) mouthwash (M; Plaque Agent, Miradent); and (3) light-curing liquid (L; Plaque test, Ivoclar). The PDs were removed with dedicated toothbrushes (T1) and the specimens were repolished (T2). The protocol was repeated after 1 week of storage in artificial saliva (staining-T3 and repolishing-T4). Color measurement were performed at baseline (T0) and all testing times (T1-T4) using a recently introduced digital colorimeter (SmartColor, Smart Vision). Color changes (ΔE ab) compared to T0 were automatically recorded by the digital instrument. The data were statistically analyzed (p < 0.05).

RESULTS

The type of PD, the polishing procedure and their interactions influenced the color stability of both restorative materials (p < 0.05). Particularly, after the second PDs application, M and L produced the highest color changes (p < 0.05), with GIC showing higher color variability than RC. Although repolishing reduced the color changes of RC (p < 0.05), it could not reestablish the initial color of GIC, irrespective of the PD used (p < 0.05). Except for RC associated with T, all materials exhibited discoloration above the clinical perceptibility (1.77) and acceptability (2.66) thresholds.

CONCLUSIONS

The influence of PDs on the color stability of RC and GIC was material-dependent. GIC showed higher color instability than RC. Repolishing could not reestablish the original color of GIC and only attenuated the color changes of the one-shade RC. The newly introduced digital colorimeter was an important tool to standardize and simplify color measurement evaluations.

CLINICAL SIGNIFICANCE

PDs can pose a potential risk to the color stability of restorative materials. Dental practitioners should be careful when recommending the frequency of at-home application of PDs, taking into consideration the material properties and the position of the restorations of each patient.

Effect of implant abutment surface treatments on bacterial biofilm composition and structure

Background

For the long-term success of dental implants, implant abutment surface should promote the attachment of oral epithelial cells and reduce bacterial adhesion. Titanium nitride (TiN) coatings show antimicrobial properties. Nevertheless, there is a lack of clinical trials that assess the biofilm formation on TiN abutments in the context of clinical practice. Thus, the objective of this study was to evaluate the effect of different abutment surfaces (machined, TiN and TiN oxidized) on bacterial biofilm composition and structure.

Materials and methods

Implant abutments were connected to the dental implants. Bacterial communities were sampled at 1 and 60 days later. The relationship between surface, periodontal indices and bacterial community dynamics was assessed using 16S rRNA metagenomics. A total of 17 patients were involved in this study (14 included in final analyses: 15 machined, 16 TiN and 14 TiN oxidized abutments).

Results

No significant differences between surfaces were found considering taxa abundance, most alpha diversity metrics or community structure. Time showed a significant effect on diversity and also on the abundance of several bacterial taxa.

Conclusions

These results indicate that the effect of the three tested abutment surfaces on biofilm structure and composition was negligible, whereas patient and time exert strong influences on bacterial biofilm formation at different scales.

Evaluation of early bacterial adhesion on CAD/CAM dental materials: an in situ study

The aim of this research was to determine if there are differences in early bacterial adhesion among CAD/CAM dental materials after 24 h exposure in the oral environment. One hundred twenty specimens were prepared according to the manufacturer's recommendations and divided into six groups: RBC (resin-based composite), PMMA (polymethyl methacrylate), PEEK (polyether ether ketone), ZP (zirconia polished), ZG (zirconia glazed), and cobalt-chromium alloy (CoCr alloy). Twenty healthy participants were instructed to carry an intraoral device with six specimens, one per group, for 24 h. Thereafter, real-time polymerase chain reaction (qPCR) and scanning electron microscopy (SEM) analyses enabled quantification and 2D view of biofilm formed on the specimens' surfaces. Kruskal-Wallis test and Dunn's post hoc analysis were used for inter-group comparison and data were presented as median (minimum-maximum). RBC specimens accumulated less bacteria, in comparison with ZG (p = 0.017) and PEEK specimens (p = 0.030), that dominated with the highest amount of adhered bacterial biofilm. PMMA, CoCr, and ZP specimens adhered more bacteria than RBC (p > 0.05), and less than ZG (p > 0.05) and PEEK (p > 0.05). The bacterial number varied considerably among participants. The obtained results enable a closer view into the susceptibility of CAD/CAM materials to microorganisms during the presence in the oral environment, which can be beneficial for a proper selection of these materials for a variety of dental restorations.

Effects of different beverages on the color stability and fluorescence of resin composites: in situ study

OBJECTIVE

To evaluate the color change (ΔE) and fluorescence (FL) of resin composites after the consumption of beverages.

MATERIALS AND METHODS

One hundred and sixty disc-shaped specimens (6 × 2 mm) of Filtek Z350 XT (FZX) and Forma (FOR) resin composites were randomized for use in devices by five volunteers who ingested 100 ml daily of red wine (RW), beer (BE), energy drink (ED) and water (WT) over 15 days. The data were collected from digital photographs and analyzed using the CIE-Lab and RGB scales to obtain ΔE and FL and statistics via two-way ANOVA (for ΔE) and ANOVA for repeated measures (for FL), α = 0.05.

RESULTS

The highest ΔE values were obtained for FZX and FOR in the RW (ΔE = 10.5 for FZX and ΔE = 9.90 for FOR) and BE (ΔE = 6.3 for FZX and ΔE = 6.1 for FOR) drinks. For FL, there were different levels of change between the composites, with a much more significant reduction in FL intensity with RW.

CONCLUSION

Beverages have the potential to stain the composites evaluated, especially alcoholic beverages.

CLINICAL SIGNIFICANCE

Before carrying out an esthetic treatment with resin composites, it is ideal to investigate the types of drinks consumed by patients, for greater predictability of treatment.

Antibiofilm and antimicrobial activity of temporary filling materials on root canals: an in situ acid challenge

The present study evaluated the antibiofilm and antimicrobial effects of temporary restorative materials on root canals after an intra-oral challenge. Seventy roots were endodontically treated and divided into 5 groups: high-viscosity glass ionomer (HV-GIC), light-activated glass ionomer (RM-GIC), zinc-oxide cement without eugenol (ZO), zinc-oxide cement with eugenol (ZOE), and unsealed roots (negative control). For 28 days, 14 participants used intra-oral devices with five roots, and drops of sucrose were applied onto them. The amount of biofilm and the bacterial counts were analyzed by Kruskal-Wallis and Dunn, and by two-way ANOVA and Tukey (α = 0.05). HV-GIC and RM-GIC better inhibit biofilm, followed by ZO and ZOE. Unsealed roots had the largest biofilm accumulation (p = 0.002) and higher bacterial penetration than restored roots (p = 0.023). A low amount of Streptococcus was found in RM-GIC and ZOE-restored roots without difference from HV-GIC (p = 0.021). The low amount of Enterococcus (p = 0.003) was found in the ZOE-restored roots, without difference from GICs.

Proteomic profile of in situ acquired pellicle on tooth and restorative material surfaces

OBJECTIVES

To evaluate and compare the proteomic profile of acquired pellicle on smooth bovine tooth and tooth-coloured restorative materials, including resin composite (RC), glass ionomer cement (GIC), and casein phosphopeptide-amorphous calcium phosphate modified GIC (CPP-ACP GIC).

METHODS

Two-hour in situ pellicles on tooth/materials specimens mounted in oral appliances worn by ten healthy adults were investigated. Pellicle proteins and corresponding unstimulated whole saliva were quantitatively analysed through liquid chromatography-tandem mass spectrometry.

RESULTS

Significantly higher amounts of protein were adsorbed onto tooth surface than restorative materials tested (4.11 ± 0.69 vs. 2.54 ± 0.38/2.98 ± 0.80/3.01 ± 0.37 µg, RC/GIC/CPP-ACP GIC). From the ten participants, 1,444 (487-1,086/person), 1,454 (645-1,051/person), 1,731 (454-1,475/person), or 1,597 (423-1,261/person) pellicle proteins were detected at least once on bovine tooth, RC, GIC, or CPP-ACP GIC, respectively, and with 1,072 (304-793/person) salivary proteins identified. Comparative quantification revealed minor differences between tooth and restorative materials pellicle profiles. High inter-individual variations in pellicle protein composition were demonstrated. Compared to the salivary protein profile, 214/57 proteins showed significantly increased/decreased abundance in pellicle formed on at least one substrate (fold change > 3.325/fold change < 0.301). Gene Ontology enrichment analysis showed some pellicle proteins detected with increased affinity to tooth/material surface were identified as being related to "calcium-dependent protein binding" or "cell-cell adhesion mediator activity".

CONCLUSION

Similar protein quantity and composition was observed in 2 h in situ pellicles formed on different smooth restorative material surfaces. The proteomic profile of pellicles appeared distinct from that of the corresponding unstimulated whole saliva.

CLINICAL SIGNIFICANCE

Host backgrounds appeared more influential on the proteomic profile of the in situ acquired pellicle than the underlying substrate characteristics among systemically and orally healthy adults. Pellicle proteins preferentially adsorbed on tooth/materials were putatively associated with calcium ion homeostasis or host-microbiota interaction.

Antibacterial Properties of Silver Nanoclusters with Carbon Support on Flexible Polymer

Here, we aimed at the preparation of an antibacterial surface on a flexible polydimethylsiloxane substrate. The polydimethylsiloxane surface was sputtered with silver, deposited with carbon, heat treated and exposed to excimer laser, and the combinations of these steps were studied. Our main aim was to find the combination of techniques applicable both against Gram-positive and Gram-negative bacteria. The surface morphology of the structures was determined by atomic force microscopy and scanning electron microscopy. Changes in surface chemistry were conducted by application of X-ray photoelectron spectroscopy and energy dispersive spectroscopy. The changes in surface wettability were characterized by surface free energy determination. The heat treatment was also applied to selected samples to study the influence of the process on layer stability and formation of PDMS-Ag or PDMS-C-Ag composite layer. Plasmon resonance effect was determined for as-sputtered and heat-treated Ag on polydimethylsiloxane. The heating of such structures may induce formation of a pattern with a surface plasmon resonance effect, which may also significantly affect the antibacterial activity. We have implemented sputtering of the carbon base layer in combination with excimer laser exposure of PDMS/C/Ag to modify its properties. We have confirmed that deposition of primary carbon layer on PDMS, followed by sputtering of silver combined with subsequent heat treatment and activation of such surface with excimer laser, led to the formation of a surface with strong antibacterial properties against two bacterial strains of S. epidermidis and E. coli.