Development of a composite resin disclosing agent based on the understanding of tooth staining mechanisms

In Vitro Assessment of Salivary Pellicle Disruption and Biofilm Removal on Titanium: Exploring the Role of Surface Hydrophobicity in Chemical Disinfection

OBJECTIVES

Peri-implantitis is mostly caused by a pathological biofilm that forms through complex processes, initiated by the formation of the salivary pellicle on implant surfaces. Understanding the nature of these pellicles and biofilm and how to remove them is important for preventing peri-implant infections and improving the success of dental implants. This study explores the characteristics of the salivary pellicle on titanium surfaces and assesses the effectiveness of different decontamination agents in eliminating the salivary pellicle and related microbial contaminations.

MATERIALS AND METHODS

Titanium surfaces were contaminated with salivary pellicles and pathological biofilms. The nature of the salivary pellicle was characterized using X-ray photoelectron spectroscopy (XPS), surface proteomics, contact angle measurements, and fluorescence microscopy. We tested six commonly used decontamination chemicals (chlorhexidine, essential oil-based mouthwash, citric acid, phosphoric acid, saline, and phosphate buffer saline) as well as newly proposed treatments such as surfactants and solvents (acetone, acetic acid, and Tween 20) for their capability to eliminate salivary pellicles and pathogenic biofilms from titanium surfaces.

RESULTS

The hydrophobic nature of the salivary pellicle on titanium surfaces limits the efficacy of commonly used hydrophilic solutions in removing pellicles and bacteria. Organic solvents and surfactants, particularly acetic acid and Tween 20, demonstrated superior effectiveness in removing the pellicle and biofilm. Acetic acid was notably effective in restoring surface composition, reducing microbial levels, and removing multispecies biofilms.

CONCLUSIONS

The use of surfactants and solvents could be a promising alternative for the treatment of biofilms on titanium surfaces. However, further studies are needed to explore their clinical applicability.

A critical analysis of research methods and experimental models to study tooth discolouration from endodontic materials

As a range of materials used in endodontics may cause tooth discolouration, exploration of factors responsible for the darkening of the tooth crown or root is warranted. This narrative review paper discusses the range of technical factors that apply in laboratory studies that assess endodontic discolouration. As an example of how these factors operate, particular examples relating to discolouration caused by endodontic medicaments containing tetracycline antibiotics are used. Following the PRILE 2021 guidelines approach, a summary of key variables to be addressed in the methodology for laboratory studies is presented, to inform future work.

Spectrophotometric evaluation of staining of different types of light-cure composite resins after exposure with different light-cure intensities: An in vitro study

Context

Relation between the adequate intensity output of curing lights on color stability of composite resin is well accepted.

Aims

To investigate the effect of different light-curing intensities and its relation to color stability of different polymerized composite resin materials using the spectophotometric analysis.

Settings and Design

Comparative in vitro study done on composite resin discs.

Subjects and Methods

A total of 180 discs comprising sixty discs prepared from three different composite resins, namely microhybrid composite resin (Filtek Z100,3M ESPE), nanohybrid composite resin (Filtek Z250 XT, 3M ESPE), and nanofilled composite resin (Filtek Z350 XT,3M ESPE) using three different light curing intensities, viz., 325-425 mW/cm², 750-850 mW/cm², and 1000-1100 mW/cm². Later these discs were stained with 2% methylene blue followed by re-absorption in absolute alcohol for supernatant solution preparation which is used for the spectrophotometric analysis.

Statistical Analysis Used

Spectrophotometric absorption values were analyzed using the one-way ANOVA test for intergroup analysis.

Results

Mean stain absorption was the highest with nanofilled composite resin (Filtek Z350 XT,3M ESPE) after exposure with light-curing intensity of 325-425 mW/cm² and least with microhybrid composite resin (Filtek Z100, 3M ESPE) after exposure with light-curing intensity of 750-850 mW/cm² and this difference found was highly significant statistically (P < 0.001).

Conclusions

Microhybrid composite resin (Filtek Z100, 3M ESPE) cured with intensity of 750-850 mW/cm² showed least stain absorption indication most color stability and esthetic function.

In vitro antibacterial activity and durability of a nano-curcumin-containing pulp capping agent combined with antimicrobial photodynamic therapy

BACKGROUND

Considering the antibacterial properties of nano-curcumin (nCur) reinforced with antimicrobial photodynamic therapy (aPDT), this study aimed to assess the antibacterial activity and durability of Activa BioActive Base/Liner (ABBL) containing nCur (nCur-ABBL) as a pulp capping agent against Streptococcus mutans, the most common cause of secondary caries.

MATERIALS AND METHODS

In this in vitro experimental study, ABBL discs containing 0.5 %, 1%, 2%, and 5% (w/w) concentrations of nCur were fabricated. After aPDT using light emitting diode (LED) at 435 ± 20 nm wavelength for 5 min, the discs were undergone aging in artificial saliva for 90 days. The antibacterial activity of the discs against S. mutans was evaluated by the disc agar diffusion test, and the number of bacterial colonies present in the biofilm formed on the disc surfaces was counted after 0, 15, 30, and 60 days of aging.

RESULTS

The maximum growth inhibition zone was noted around the 5% nCur-ABBL discs. Increasing the concentration of nCur from 0.5 % to 5% combined with aPDT significantly decreased the number of S. mutans colonies in the biofilm over time (P < 0.05). nCur-ABBL discs containing 2% and 5% nCur had no difference in antibacterial activity at any time point up to 60 days (P > 0.05).

CONCLUSION

According to our data, 5% nCur-ABBL revealed the largest growth inhibition zone in S. mutans culture. Moreover, 5% nCur can serve as an excellent ABBL additive in aPDT producer against S. mutans biofilms up to 60 days of aging period.

Materials Testing for the Development of Biocompatible Devices through Vat-Polymerization 3D Printing

Light-based 3D printing techniques could be a valuable instrument in the development of customized and affordable biomedical devices, basically for high precision and high flexibility in terms of materials of these technologies. However, more studies related to the biocompatibility of the printed objects are required to expand the use of these techniques in the health sector. In this work, 3D printed polymeric parts are produced in lab conditions using a commercial Digital Light Processing (DLP) 3D printer and then successfully tested to fabricate components suitable for biological studies. For this purpose, different 3D printable formulations based on commercially available resins are compared. The biocompatibility of the 3D printed objects toward A549 cell line is investigated by adjusting the composition of the resins and optimizing post-printing protocols; those include washing in common solvents and UV post-curing treatments for removing unreacted and cytotoxic products. It is noteworthy that not only the selection of suitable materials but also the development of an adequate post-printing protocol is necessary for the development of biocompatible devices.

A Review on the Biocompatibility of PMMA-Based Dental Materials for Interim Prosthetic Restorations with a Glimpse into their Modern Manufacturing Techniques

This paper's primary aim is to outline relevant aspects regarding the biocompatibility of PMMA (poly(methyl methacrylate))-based materials used for obtaining interim prosthetic restorations, such as the interaction with oral epithelial cells, fibroblasts or dental pulp cells, the salivary oxidative stress response, and monomer release. Additionally, the oral environment's biochemical response to modern interim dental materials containing PMMA (obtained via subtractive or additive methods) is highlighted in this review. The studies included in this paper confirmed that PMMA-based materials interact in a complex way with the oral environment, and therefore, different concerns about the possible adverse oral effects caused by these materials were analyzed. Adjacent to these aspects, the present work describes several advantages of PMMA-based dental materials. Moreover, the paper underlines that recent scientific studies ascertain that the modern techniques used for obtaining interim prosthetic materials, milled PMMA, and 3D (three-dimensional) printed resins, have distinctive advantages compared to the conventional ones. However, considering the limited number of studies focusing on the chemical composition and biocompatibility of these modern interim prosthetic materials, especially for the 3D printed ones, more aspects regarding their interaction with the oral environment need to be further investigated.

Comparative adsorption profiles of basal lamina proteome and gingival cells onto dental and titanium surfaces

Titanium (Ti) dental implants are susceptible to bacterial infections and failure due to lack of proper epithelial seal. Epithelial cells establish a strong epithelial seal around natural teeth by the deposition of basal lamina (BL) proteins that adsorb on the tooth surface. This seal can even be re-established onto cementum or dentin following injury or periodontal therapy. However, it is unclear how tooth surfaces promote this cell attachment and protein adsorption. Understanding the interactions between BL proteins and epithelial cells with dentin and Ti will facilitate the development of implant surfaces that promote the formation of an epithelial seal and improve the success of periodontal therapy and wound healing on natural teeth. To study these interactions, we used a surface proteomic approach to decipher the adsorption profile of BL proteins onto Ti and dentin, and correlated these adsorption profiles with in vitro interactions of human gingival fibroblasts and epithelial cells. Results showed that dentin adsorbed higher amounts of key BL proteins, particularly laminin and nidogen-1, and promoted more favorable interactions with epithelial cells than Ti. Next, dentin specimens were deproteinized or partially demineralized to determine if its mineral or protein component was responsible for BL adsorption and cell attachment. Deproteinized (mineral-rich) and partially demineralized (protein-rich) dentin specimens revealed BL proteins (i.e. laminin and nidogen-1) and epithelial cells interact preferentially with dentinal proteins rather than dentin mineral. These findings suggest that, unlike Ti, dentin and, in particular, dentinal proteins have a selective affinity to BL proteins that enhance epithelial cell attachment.

STATEMENT OF SIGNIFICANCE

It is remains unclear why natural teeth, unlike titanium dental implants, promote the formation of an epithelial seal that protects them against the external environment. This study used a surface screening approach to analyze the adsorption of proteins produced by epithelial tissues onto tooth-dentin and titanium surfaces, and correlate it with the behaviour of cells. This study shows that tooth-dentin, in particular its proteins, has a higher selective affinity to certain adhesion proteins, and subsequently allows more favourable interactions with epithelial cells than titanium. This knowledge could help in developing new approaches for re-establishing and maintaining the epithelial seal around teeth, and could pave the way for developing implants with surfaces that allow the formation of a true epithelial seal.

Assessing adhesive remnant removal and enamel damage with ultraviolet light: An in-vitro study

INTRODUCTION

Our objective was to assess the amounts of adhesive remnant and enamel damage when removing composite under conventional lighting and ultraviolet (UV) light.

METHODS

Thirty-eight premolars were divided into 2 groups according to the lighting used for adhesive removal. A multifluted tungsten-carbide bur at low speed was used for this process in both groups. The UV group received conventional lighting associated with UV light, and the conventional group received conventional lighting only. The amounts of adhesive remnant were calculated using images of the teeth taken under UV light with software. Scanning electron microscopy images of epoxy adhesive replicas of the teeth made before bonding and after adhesive removal were graded according to the enamel damage index (EDI), and the difference between the final and initial EDI scores was used for assessment of the enamel damage. To detect differences between the groups, the Mann-Whitney test was used to analyze the data from the adhesive remnant index and the EDI.

RESULTS

The conventional group had more adhesive left on the enamel (P <0.001) than did the UV group. There was no difference between groups for the EDI (P = 0.729).

CONCLUSIONS

UV lighting allows significantly more adhesive removal without increasing the damage caused to the enamel.

Diagenesis-inspired reaction of magnesium ions with surface enamel mineral modifies properties of human teeth

Mineralized tissues such as teeth and bones consist primarily of highly organized apatitic calcium-phosphate crystallites within a complex organic matrix. The dimensions and organization of these apatite crystallites at the nanoscale level determine in part the physical properties of mineralized tissues. After death, geological processes such as diagenesis and dolomitization can alter the crystallographic properties of mineralized tissues through cycles of dissolution and re-precipitation occurring in highly saline environments. Inspired by these natural exchange phenomena, we investigated the effect of hypersalinity on tooth enamel. We discovered that magnesium ions reacted with human tooth enamel through a process of dissolution and re-precipitation, reducing enamel crystal size at the surface of the tooth. This change in crystallographic structure made the teeth harder and whiter. Salt-water rinses have been used for centuries to ameliorate oral infections; however, our discovery suggests that this ancient practice could have additional unexpected benefits.

STATEMENT OF SIGNIFICANCE

Here we describe an approach inspired by natural geological processes to modify the properties of a biomineral - human tooth enamel. In this study we showed that treatment of human tooth enamel with solutions saturated with magnesium induced changes in the nanocrystals at the outer surface of the protective enamel layer. As a consequence, the physical properties of the tooth were modified; tooth microhardness increased and the color shade became whiter, thus suggesting that this method could be used as a clinical treatment to improve dental mechanical properties and esthetics. Such an approach is simple and straightforward, and could also be used to develop new strategies to synthesize and modify biominerals for biomedical and industrial applications.