Aim
To discuss the causes and management of tooth crown discolouration following regenerative/revitalization endodontic therapy (RET) and to present the decision‐making process affecting three ...RET‐related cases of crown discolouration.
Summary
This case series outlines several approaches used in the management of post‐RET discolouration. The cases highlight the influence of the material used in creating a coronal seal on the choice and success of the management techniques provided. The first two cases highlight successful management of post‐RET discolouration through the use of internal–external bleaching. The use of internal bleaching in the third case was not recommended; therefore, external bleaching followed by a direct composite veneer was carried out.
Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus ...contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR:
Mycobacterium
spp.,
Mycobacterium avium
complex,
Acanthamoeba
spp.,
Pseudomonas aeruginosa
,
Legionella pneumophilia
, and
Stenotrophomonas maltophilia
. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria,
Pseudomonas
increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of
Fusarium
genus. After the mobilisation phase,
Pseudomonas
continued being the most abundant genus at 24°C, followed by
Sphingobium
and
Sphingomonas.
For biofilm fungal communities after the mobilisation phase, Helotiales
incertae sedis
and
Fusarium
were the most abundant taxa. Results from qPCR showed a higher relative abundance of
Mycobacterium
spp. on day 30 and
M. avium
complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.
This study investigated the effect of silver diamine fluoride (SDF) and potassium iodide (KI) treatment on secondary caries prevention and tooth discolouration in glass ionomer cement (GIC) ...restoration. Cervical GIC restorations were done on 30 premolars with: Group 1, SDF + KI; Group 2, SDF (positive control); Group 3, no treatment (negative control). After cariogenic biofilm challenge, the demineralisation of dentine adjacent to the restoration was evaluated using micro-computed tomography (micro-CT) and Fourier transform infrared (FTIR) spectroscopy. The colour of dentine adjacent to the restoration was assessed using CIELAB system at different time points. Total colour change (∆E) was calculated and was visible if ∆E > 3.7. Micro-CT showed the outer lesion depths for Groups 1, 2 and 3 were 91 ± 7 µm, 80 ± 7 µm and 119 ± 8 µm, respectively (
< 0.001; Group 2 < Group 1 < Group 3). FTIR found that there was a significant difference in amide I-to-hydrogen phosphate ratio among the three groups (
< 0.001; Group 2 < Group 1 < Group 3). ∆E of Groups 1, 2 and 3 after biofilm challenge were 22.5 ± 4.9, 70.2 ± 8.3 and 2.9 ± 0.9, respectively (
< 0.001; Group 3 < Group 1 < Group 2). SDF + KI treatment reduced secondary caries formation on GIC restoration, but it was not as effective as SDF treatment alone. Moreover, a perceptible staining on the restoration margin was observed, but the intensity of discolouration was less than that with solely SDF treatment.
Objectives
The aim of this research was to analyse the dental discolouration caused by mineral trioxide aggregate (MTA) induced by bismuth oxide and also assess the colour stability of other dental ...cements.
Materials and methods
Bismuth oxide, calcium tungstate and zirconium oxide were placed in contact with sodium hypochlorite for 24 h after which they were dried and photographed. Phase analyses were performed by X-ray diffraction (XRD) of radiopacifiers before and after immersion in sodium hypochlorite. Furthermore, teeth previously immersed in water or sodium hypochlorite were filled with MTA Angelus, Portland cement (PC), PC with 20 % zirconium oxide, PC with 20 % calcium tungstate and Biodentine. Teeth were immersed for 28 days in Hank’s balanced salt solution after which they were sectioned and characterized using scanning electron microscopy (SEM) with energy-dispersive mapping and stereomicroscopy.
Results
Bismuth oxide in contact with sodium hypochlorite exhibited a change in colour from light yellow to dark brown. XRD analysis demonstrated peaks for radiopacifier and sodium chloride in samples immersed in sodium hypochlorite. The SEM images of the dentine to material interface showed alteration in material microstructure for MTA Angelus and Biodentine with depletion in calcium content in the material. The energy-dispersive maps showed migration of radiopacifier and silicon in dentine.
Conclusions
MTA Angelus in contact with a tooth previously immersed in sodium hypochlorite resulted in colour alteration at the cement/dentine interface.
Clinical relevance
MTA Angelus should not be used after irrigation with sodium hypochlorite as this will result in tooth discoloration.
In this paper, degradation mechanisms of optical materials, used in the light emitting diode (LED)-based products, are reviewed. The LED lighting is one of the fastest technology shifts in human ...history. Lighting accounts for almost 20% of the global electrical energy use, inferring that replacement of traditional lighting sources with LEDs with higher efficiencies will have major positive implications for the global energy consumption. Organic optical materials are key components in LEDs in the sense that they control the functionality of the device and they have decisive effects on the durability and reliability of LEDs. This paper aims at describing the influences of chemical structure and service conditions on the degradation mechanisms of organic optical materials in LEDs which lead to the lumen depreciation, discolouration, and colour shift of the LED light output. The contributions of different degradation mechanisms of optical and package materials in LED-based products to the lumen depreciation and colour shift are methodically reviewed.
Introduction: Chlorhexidine is commonly used to treat dental diseases as a broad-spectrum topical antibacterial medication. Povidone-iodine is a water soluble blend of molecular iodine and the ...solubiliser polyvinyl pyrrolidone. Amsarveda (pharmaceutical company) developed a natural mouth sanitiser with liposomal curcumin. Aim: Comparative evaluation of the effect of chlorhexidine mouthwash, povidone-iodine gargle and herbal mouth sanitiser on colour stability and surface roughness of conventional nanohybrid composite. Materials and Methods: This in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at KM Shah Dental College and Hospital, Vadodara, Gujarat, India, from November 2020 to June 2021. Total 60 extracted human permanent maxillary premolar teeth were selected. Class V restorations were performed on the extracted teeth with nanohybrid composite resin. The samples were divided into three groups by computer randomisation. The three test solution groups (n=20 each) ie., group A- chlorhexidine 0.2% mouthwash, group B has povidone-iodine (2%), group C- herbal mouth sanitiser. The colour change and surface roughness of all the samples were measured before and 15 days after immersion into the test solutions. The data was collected and statistically analysed using one-way Analysis of Variance (ANOVA) and Tukey’s post-hoc test. Results: The ΔE values for all three groups show a statistically significant difference (p-value <0.001). The mean baseline and after 15 days values for surface roughness in groups A and B showed a statistically significant difference (p-value <0.001). Whereas, no statistically significant difference in group C (p-value=0.654). Conclusion: Based on the results of the present study, it can be stated that the povidone-iodine gargle showed more surface roughness and colour change of conventional nanohybrid composite followed by chlorhexidine mouthwash and herbal mouth sanitiser.
Meat discoloration and fat oxidation are the major quality issues in pangasius fillet during storage. In this study, aqueous seaweed extracts prepared from Padina tetrastromatica using three ...protocols were evaluated based on its total phenolic content and antioxidant activities. Based on the ideal result, different concentration of seaweed extracts ranging from 0.5 to 2% (v/v) were used for dipping the pangasius fillet. Individual fillet samples were packed stored under chilled condition (2 °C). Among the quality parameters proximate composition, total volatile basic nitrogen, free fatty acids, thiobarbituric acid reactant substances, myoglobin content, aerobic plate count, instrumental colour and sensory analysis were carried out at regular intervals of 4 days. Seaweed extract containing phenolics reduced the myoglobin oxidation which is positively correlated with redness values. Among the different treatments 2% aqueous extract showed reduction in total volatile basic nitrogen, rancidity, total bacterial count, sensory quality parameters and effectively reduced the spoilage and meat discoloration of fillet up to 20 days. It can be concluded that aqueous seaweed extract can be used as a natural additive for improving meat colour and extending the storage life of fishery products under chilled conditions.
•Padina seaweed extract used as dip treatment for improving the quality of fish fillet.•Phenolic content and antioxidant activity of the seaweeds depend on the extraction method.•Padina extract showed good anti-oxidant and antimicrobial properties.•Remarkable reduction in lipid oxidation and meat colour improvement was observed.•Fillets treated with 2% seaweed extract exhibited better quality and longer shelf life.
Drinking water distribution systems host complex microbial communities as biofilms that interact continuously with delivered water. Understanding the diversity, behavioural and functional ...characteristics will be a requisite for developing future monitoring strategies and protection against water-borne health risks. To improve understanding, this study investigates mobilisation and accumulation behaviour, microbial community structure and functional variations of biofilms developing on different pipe materials from within an operational network. Samples were collected from four pipes during a repeated flushing operation three months after an initial visit that used hydraulic forces to mobilise regenerating biofilms yet without impacting the upstream network. To minimise confounding factors, test sections were chosen with comparable daily hydraulic regimes, physical dimensions, and all connected straight of a common trunk main and within close proximity, hence similar water chemistry, pressure and age. Taxonomical results showed differences in colonising communities between pipe materials, with several genera, including the bacteria Pseudomonas and the fungi Cladosporium, present in every sample. Diverse bacterial communities dominated compared to more homogeneous fungal, or mycobiome, community distribution. The analysis of bacterial/fungal networks based on relative abundance of operational taxonomic units (OTUs) indicated microbial communities from cast iron pipes were more stable than communities from the non-ferrous pipe materials. Novel analysis of functional traits between all samples were found to be mainly associated to mobile genetic elements that play roles in determining links between cells, including phages, prophages, transposable elements, and plasmids. The use of functional traits can be considered for development in future surveillance methods, capable of delivering network condition information beyond that of limited conventional faecal indicator tests, that will help protect water quality and public health.
Display omitted
•Initial flushing steps yielded samples with highest microbial diversity.•Pipe material influenced the structure of attached microbial communities.•Network hydraulics influenced material accumulation and microbial composition.•The most abundant functional traits were mobile genetic elements.•The most stable microbial networks were associated with cast iron pipes.
Mineral trioxide aggregate (MTA) is a dental material used extensively for vital pulp therapies (VPT), protecting scaffolds during regenerative endodontic procedures, apical barriers in teeth with ...necrotic pulps and open apices, perforation repairs as well as root canal filling and root‐end filling during surgical endodontics. A number of bioactive endodontic cements (BECs) have recently been introduced to the market. Most of these materials have calcium and silicate in their compositions; however, bioactivity is a common property of these cements. These materials include the following: BioAggregate, Biodentine, BioRoot RCS, calcium‐enriched mixture cement, Endo‐CPM, Endocem, EndoSequence, EndoBinder, EndoSeal MTA, iRoot, MicroMega MTA, MTA Bio, MTA Fillapex, MTA Plus, Neo MTA Plus, Ortho MTA, Quick‐Set, Retro MTA, Tech Biosealer, and TheraCal LC. It has been claimed that these materials have properties similar to those of MTA but without the drawbacks. In Part I of this review, the available information on the chemical composition of the materials listed above was reviewed and their applications for VPT was discussed. In this article, the clinical applications of MTA and other BECs will be reviewed for apexification, regenerative endodontics, perforation repair, root canal filling, root‐end filling, restorative procedures, periodontal defects and treatment of vertical and horizontal root fractures. In addition, the literature regarding the possible drawbacks of these materials following their clinical applications is reviewed. These drawbacks include their discolouration potential, systemic effects and retreatability following use as a root filling material. Based on selected keywords, all publications were searched regarding the use of MTA as well as BECs for the relevant clinical applications. Numerous publications were found regarding the use of BECs for various endodontic applications. The majority of these investigations compared BECs with MTA. Despite promising results for some materials, the number of publications using BECs for various clinical applications was limited. Furthermore, most studies had several methodological shortcomings and low levels of evidence.
•The colors of metMb and oxyMb were changed by PAS treatment.•The structures of metMb and oxyMb were damaged by PAS treatment.•Relationship between the discoloration and the changed structure was ...clarified.•H2O2 was the main reason for structure destruction and color transformation.
Effects of plasma-activated solution (PAS) on the colour and structure of metmyoglobin (metMb) and oxymyoglobin (oxyMb) were investigated and the relationship between discolouration and structure changes was clarified for the first time. Results showed that the colour of PAS-treated metMb faded first, followed by green discolouration, while PAS-treated oxyMb turned from bright red to reddish-brown and then towards green in the end. It was due to the accumulation of H2O2, nitrite and nitrate in PAS with prolonging plasma treatment times. Also, the low concentrations of active species in PAS cannot influence the colour and structure of metMb and oxyMb. The accumulation of active species of H2O2 in PAS was the main reason for destructing myoglobin structure and transforming its colour with prolonging treatment time. Therefore, the concentration of H2O2 should be adjusted to a low level for treating red meats as their colour appearance is mainly determined by metMb and oxyMb.
PDF
