Diversity and Geographic Distribution of Ligninolytic Fungi Associated With Castanopsis sieboldii Leaf Litter in Japan

The diversity and geographic pattern of ligninolytic fungi were investigated within the distribution range of an evergreen tree, Castanopsis sieboldii (Fagaceae), in Japan. Fungal isolates obtained from 18 sites in subtropical and temperate regions in Japan were classified into 50 operational taxonomic units in Ascomycota and Basidiomycota according to the base sequence of the rDNA internal transcribed spacer region. Ordination by nonmetric multidimensional scaling showed the separation of fungal compositions between the study sites which was significantly related to the latitude, longitude, and mean annual temperature (MAT) of the study sites. We applied variation partitioning to separate the magnitude of the climatic, spatial, and leaf property factors and found the roles of MAT and spatial factors in structuring fungal assemblages, suggesting the importance of both niche processes and such non-niche processes as priority effect and dispersal limitation. The bleached area on leaf litter was greater at sites with higher MAT and precipitation located at lower latitudes and at sites where some major ligninolytic fungi occurred at greater relative frequencies, indicating that not only the climatic conditions but also the biogeographic patterns of distribution of ligninolytic fungi influence the decomposition of lignin in leaf litter.

Global gene expression patterns in Porites white patch syndrome: Disentangling symbiont loss from the thermal stress response in reef-building coral

The mechanisms resulting in the breakdown of the coral symbiosis once the process of bleaching has been initiated remain unclear. Distinguishing the process of symbiont loss from the thermal stress response may shed light on the cellular and molecular pathways involved in each process. This study examined physiological changes and global gene expression patterns associated with white patch syndrome (WPS) in Porites lobata, which manifests in localized bleaching independent of thermal stress. In addition, a meta-analysis of global gene expression studies in other corals and anemones was used to contrast differential regulation as a result of disease and thermal stress from patterns correlated with symbiotic state. Symbiont density, chlorophyll a content, holobiont productivity, instant calcification rate, and total host protein content were uniformly reduced in WPS relative to healthy tissue. While expression patterns associated with WPS were secondary to fixed effects of source colony, specific functional enrichments combined with a lack of immune regulation suggest that the viral infection putatively giving rise to this condition affects symbiont rather than host cells. Expression in response to WPS also clustered independently of patterns in white syndrome impacted A. hyacinthus, further supporting a distinct aetiology of this syndrome. Expression patterns in WPS-affected tissues were significantly correlated with prior studies that examined short-term thermal stress responses independent of symbiotic state, suggesting that the majority of expression changes reflect a nonspecific stress response. Across studies, the magnitude and direction of expression change among particular functional enrichments suggests unique responses to stressor duration and highlights distinct responses to bleaching in an anemone model.

Conservative esthetic management of severe dental fluorosis with in-office power bleaching

Fluorosis is an endemic disease, prevailing in about 25 countries globally. Dental fluorosis is an acquired defect of enamel due to the exposure of an individual to excessive fluoride levels during tooth development. It could result in mild-to-severe discoloration of teeth, which might necessitate esthetic correction. Bleaching is one of the common treatment modalities used in the esthetic correction of such cases. In-office power bleaching is one of the techniques of tooth bleaching that involves clinical application and activation of the bleaching agent with light to accelerate the bleaching process. This case report describes the esthetic correction of severe dental fluorosis by power bleaching, without any need for invasive treatment. This report suggests that in-office power bleaching is an effective and conservative method for esthetic correction of tooth discoloration in severe dental fluorosis.

"The unfair drive to be fair": Psychosocial aspects and implications of the use of skin lightening agents

The quest to be fair is not a concept of the new world. For centuries untold, having a lighter skin tone has been considered as a trait of beauty and supremacy. Society implicates fairness as a factor for getting a prospective life partner. Media portrays fair skin tone as a predecessor for success. These subtle influences affect young minds and drive them towards wanting fair skin. Physicians observe that it is one of the most common forms of body dysmorphic disorder. This article aims to highlight the psychosocial factors that mold this mentality and the possible ill effects it can have on a person, both psychologically as well as physically.

Physical Properties of Carboxymethyl Cellulose from Palm Bunch and Bagasse Agricultural Wastes: Effect of Delignification with Hydrogen Peroxide

The aim of this work was to synthesize carboxymethyl cellulose (CMC) and produce CMC films from the cellulose of palm bunch and bagasse agricultural waste. The effect of various amounts of H₂O₂ (0-40% v/v) during delignification on the properties of cellulose, CMC, and CMC films was studied. As the H₂O₂ content increased, yield and the lignin content of the cellulose from palm bunch and bagasse decreased, whereas lightness (L*) and whiteness index (WI) increased. FTIR confirmed the substitution of a carboxymethyl group on the cellulose structure. A higher degree of substitution of CMC from both sources was found when 20%-30% H₂O₂ was employed. The trend in the L* and WI values of each CMC and CMC film was related to those values in their respective cellulose. Bleaching each cellulose with 20% H₂O₂ provided the cellulose with the highest viscosity and the CMC films with the greatest mechanical (higher tensile strength and elongation at break) and soluble attributes, but the lowest water vapor barrier. This evidence indicates that cellulose delignification with H₂O₂ has a strong effect on the appearance and physical properties of both CMCs.

[Study of clinical and histological features in professional teeth whitening]

The aim of the study was to study clinical and histological changes in the treatment of discoloration using different systems for professional tooth whitening. The study involved 76 patients. Patients of group 1 had their teeth whitened by the Amazing White Universal Extra photochemical activation system, and group 2 had their teeth whitened by the Beyond Polus system. Each group was divided into 3 more subgroups depending on the method of remineralization and the applied toothpaste (SENSITIVE ULTRA and SENSODYNE Rapid Relief). To assess teeth hyperesthesia before, immediately after and 14 days after the bleaching procedure, we used the prevalence index of teeth hyperesthesia, the intensity index of teeth hyperesthesia, and the Schiff sample. We also used a digital rating scale for patients. 100 teeth extracted for orthodontic indications were subjected to histological examination. The occurrence of hyperesthesia of teeth during professional bleaching was revealed in 100% of cases. Significant structural changes were registered in the enamel and dentin of the teeth, most pronounced during photo-whitening. The treatment based on zinc-substituted hydroxyapatite carbonate in combination with laserophonophoresis against the background of use the toothpaste SENSODYNE Rapid Relief had the greatest remineralizing effect.

Comparison of the effects of whitening and conventional toothpastes on the wear rate of a composite resin

Considering the importance of the effect of abrasion on a restoration's durability and the high volume of abrasive materials in whitening toothpastes, it is necessary to evaluate whitening toothpastes to determine the degree of abrasion they cause in composite resins. This in vitro study evaluated the abrasive effect of 3 bleaching toothpastes on Filtek Z250 composite resin. Three whitening toothpastes (Oral-B Pro-Expert Whitening, Signal White Now, and Crest 3D White Arctic Fresh) were studied, and Crest Complete 7 conventional daily toothpaste was used as a control group. Forty disc-shaped composite resin specimens, 7 mm in diameter × 2 mm thick, were polymerized according to the manufacturer's instructions. The specimens were divided into 4 groups of 10 each according to the toothpaste applied. An electronic scale was used to record the weight of each specimen before and after simulated toothbrushing (20,000 cycles to simulate 2 years). The weight loss after toothbrushing was calculated, and data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). The Kruskal-Wallis test showed that there was a statistically significant difference in the weight loss of the specimens depending on the toothpaste used (P = 0.01). The Mann-Whitney U test indicated that Crest 3D White (P = 0.01) and Signal White Now (P = 0.005) were significantly more abrasive than Crest Complete 7 (control). There was no statistically significant difference in abrasion between Oral-B Pro-Expert Whitening and Crest Complete 7 (P = 0.034). According to the results of this study, whitening toothpastes can increase the amount of composite resin abrasion, and the specific toothpaste used affects the amount of abrasion.

Home-based chemically induced whitening (bleaching) of teeth in adults: A summary of a systematic review

The demand for whiter teeth has been increasing, and home-based remedies are a popular way of whitening the teeth. These products may be prescribed by the dentist or purchased over the counter and comprise different modes to whiten the teeth and are administered in a range of ways by the person. This review found that the evidence was insufficient to draw reliable conclusions about the intervention, i.e., the use of these whitening products. The results indicated that people may experience side effects that irritate the mouth and gums. Therefore, nurses should direct people who are interested in teeth whitening to their dental professional for a discussion.

Post-orthodontic recontouring of anterior teeth using composite injection technique with a digital workflow

OBJECTIVE

Restorative treatment of anterior teeth is often required as the final step of orthodontic therapy to optimize the esthetics and function. This case report presents a direct minimally invasive approach for post-orthodontic recontouring of anterior teeth using the composite injection technique with a digital workflow.

CLINICAL CONSIDERATIONS

The extraction of central incisors with short roots was indicated to resolve maxillary anterior crowding. The gained space was closed with lateral incisors, and it was necessary to recontour them and canines to resemble central and lateral incisors, respectively. The restorations were digitally designed, and a transparent silicone index was fabricated from a 3D-printed cast of the digital wax-up. After lateral incisors and canines were bonded with a universal adhesive in the etch-and-rinse mode, a highly filled injectable composite resin was applied into the index. The restorative treatment was preceded by gingivectomy using an Er:YAG laser and home bleaching.

CONCLUSIONS

In cases where more complex recontouring of anterior teeth is necessary, the composite injection technique could be a suitable alternative to indirect restorations, because it is straightforward, cost-effective, and does not require any preparation. The digital workflow simplified and expedited the treatment while contributing to its precision.

CLINICAL SIGNIFICANCE

Post-orthodontic recontouring using direct composite restorations is well accepted by patients due to low cost and non-invasiveness. However, in complicated cases, the free-hand technique is time-consuming and technique-sensitive. The presented composite injection technique with a digital workflow significantly simplifies and expedites the composite placement while predictably enhancing the treatment outcome.

Genome-wide SNP analysis reveals an increase in adaptive genetic variation through selective breeding of coral

Marine heat waves are increasing in magnitude, duration, and frequency as a result of climate change and are the principal global driver of mortality in reef-building corals. Resilience-based genetic management may increase coral heat tolerance, but it is unclear how temperature responses are regulated at the genome level and thus how corals may adapt to warming naturally or through selective breeding. Here we combine phenotypic, pedigree, and genomic marker data from colonies sourced from a warm reef on the Great Barrier Reef reproductively crossed with conspecific colonies from a cooler reef to produce combinations of warm purebreds and warm-cool hybrid larvae and juveniles. Interpopulation breeding created significantly greater genetic diversity across the coral genome compared to breeding between populations and maintained diversity in key regions associated with heat tolerance and fitness. High-density genome-wide scans of single nucleotide polymorphisms (SNPs) identified alleles significantly associated with larval families reared at 27.5°C (87-2,224 loci), including loci putatively associated with proteins involved in responses to heat stress (cell membrane formation, metabolism, and immune responses). Underlying genetics of these families explained 43% of PCoA multilocus variation in survival, growth, and bleaching responses at 27.5°C and 31°C at the juvenile stage. Genetic marker contribution to total variation in fitness traits (narrow-sense heritability) was high for survival but not for growth and bleaching in juveniles, with heritability of these traits being higher at 31°C relative to 27.5°C. While based on only a limited number of crosses, the mechanistic understanding presented here demonstrates that allele frequencies are affected by one generation of selective breeding, key information for the assessments of genetic intervention feasibility and modelling of reef futures.

Bleaching of severely darkened nonvital tooth case report-48 months clinical control

OBJECTIVE

To record in detail, the long-term success of a bleaching treatment employing hydrogen peroxide in a severely darkened tooth.

CLINICAL CONSIDERATIONS

Tooth discoloration is an important aesthetic complain of patients. Because it is a relatively common condition, different materials and techniques capable of restoring the tooth color in a minimally invasive, conservative, and longstanding manner were developed. In this case, it was used the association between mediate (walking bleach) and immediate (internal/external) bleaching techniques using hydrogen peroxide as the main agent.

CONCLUSION

The association of techniques was a conservative therapeutic solution to restore the natural color of the right upper central incisor, which was darkened after an endodontic treatment performed more than twenty years ago. The bleaching protocol used presented no risk to the patient, such as cervical resorption and the color was stable over a 48 months period, showing the success of the protocol proposed for this case.

CLINICAL SIGNIFICANCE

There is a possibility to severely darkened teeth receive an adequate bleaching treatment protocol, which can successfully restore the aesthetics and natural color in a conservative and long lasting way.

Forecasting intensifying disturbance effects on coral reefs

Anticipating future changes of an ecosystem's dynamics requires knowledge of how its key communities respond to current environmental regimes. The Great Barrier Reef (GBR) is under threat, with rapid changes of its reef-building hard coral (HC) community structure already evident across broad spatial scales. While several underlying relationships between HC and multiple disturbances have been documented, responses of other benthic communities to disturbances are not well understood. Here we used statistical modelling to explore the effects of broad-scale climate-related disturbances on benthic communities to predict their structure under scenarios of increasing disturbance frequency. We parameterized a multivariate model using the composition of benthic communities estimated by 145,000 observations from the northern GBR between 2012 and 2017. During this time, surveyed reefs were variously impacted by two tropical cyclones and two heat stress events that resulted in extensive HC mortality. This unprecedented sequence of disturbances was used to estimate the effects of discrete versus interacting disturbances on the compositional structure of HC, soft corals (SC) and algae. Discrete disturbances increased the prevalence of algae relative to HC while the interaction between cyclones and heat stress was the main driver of the increase in SC relative to algae and HC. Predictions from disturbance scenarios included relative increases in algae versus SC that varied by the frequency and types of disturbance interactions. However, high uncertainty of compositional changes in the presence of several disturbances shows that responses of algae and SC to the decline in HC needs further research. Better understanding of the effects of multiple disturbances on benthic communities as a whole is essential for predicting the future status of coral reefs and managing them in the light of new environmental regimes. The approach we develop here opens new opportunities for reaching this goal.

Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures

Purpose

The aim of this study was to evaluate the effect of erosive/abrasive cycles and two different levels of abrasiveness of dentifrices over enamel and dentin subjected to bleaching.

Methods

Enamel and dentin bovine specimens were prepared and submitted to an at-home bleaching treatment using 9.5% hydrogen peroxide gel, which was applied daily (30 min/14 days). Concomitant with bleaching, an erosive cycle was performed using citric acid (0.3%, pH 3.8, 5 mins, 3×/day), followed by immersions in artificial saliva for remineralization (30 mins). Abrasion was done with two (high and low abrasiveness) dentifrices (2×/day, 120 seconds) after the first and third erosive immersion each day. Enamel and dentin softening were assessed by microhardness and erosive tooth wear by optical profilometry. Data were submitted to repeated measures ANOVA, followed by the Tukey’s test with a significance level of 5%.

Results

For the enamel and considering the erosive-abrasive cycle, significant differences were found between the groups tested, the bleaching, and the abrasiveness of the dentifrice tested; however, the final microhardness values were significantly lower than the initial ones. For dentin, differences were found between the eroded/abrasion and the non-eroded/abrasion groups, with the former presenting lower microhardness values compared with the latter. In addition, bleaching decreased the microhardness values only for the highly abrasive dentifrice, and the final values were lower than for the initial ones for all tested groups.

Conclusion

The use of high and low abrasiveness dentifrices during bleaching and concomitant with erosion/abrasion cycles is more harmful to dentin than to enamel.

Clinical Relevance

Although bleaching is considered a conservative treatment, it can cause deleterious effects to dental hard tissue. The association of an at-home bleaching technique with erosion and high- or low- abrasive dentifrices harms dentin more than enamel.

Combination Analysis of Metatranscriptome and Metagenome Reveal the Composition and Functional Response of Coral Symbionts to Bleaching During an El Niño Event

With the abnormal rise in ocean temperatures globally in recent years, coral bleaching is becoming common and serious. However, the response mechanisms and processes of coral symbionts to bleaching are not well understood. In this study, metagenomics and metatranscriptomics were used to explore the composition of coral symbionts and their functions in response to coral bleaching. All four bleaching coral species displayed a significant reduction of the abundance and function of Dinophyceae-like eukaryotes at the DNA and RNA levels. However, different species of bleaching coral have their own characteristic symbiotic components. Bleaching Acropora tenuis and Goniastrea minuta corals exhibited a very high abundance of prokaryotes and associated gene functions, especially for opportunistic bacteria. In contrast, algae and fungi were identified as the main microbial associate components and had relatively high RNA abundance in bleaching Pocillopora verrucosa and Pocillopora meandrina. Different coral species, whether unbleached or bleaching, have the same symbiotic taxa that perform the same biological functions in vivo. Different stages of bleaching, or transitional states, were identified by different genome content and functional gene abundance among bleaching corals. These stages should be considered in future coral bleaching studies to accurately determine symbiont structure and function. An implicit hypothesis is that there is a causal relationship between the stability of eukaryotic communities and coral bleaching.

Bleaching-driven reef community shifts drive pulses of increased reef sediment generation

The ecological impacts of coral bleaching on reef communities are well documented, but resultant impacts upon reef-derived sediment supply are poorly quantified. This is an important knowledge gap because these biogenic sediments underpin shoreline and reef island maintenance. Here, we explore the impacts of the 2016 bleaching event on sediment generation by two dominant sediment producers (parrotfish and Halimeda spp.) on southern Maldivian reefs. Our data identifies two pulses of increased sediment generation in the 3 years since bleaching. The first occurred within approximately six months after bleaching as parrotfish biomass and resultant erosion rates increased, probably in response to enhanced food availability. The second pulse occurred 1 to 3 years post-bleaching, after further increases in parrotfish biomass and a major (approx. fourfold) increase in Halimeda spp. abundance. Total estimated sediment generation from these two producers increased from approximately 0.5 kg CaCO3 m-2 yr-1 (pre-bleaching; 2016) to approximately 3.7 kg CaCO3 m-2 yr-1 (post-bleaching; 2019), highlighting the strong links between reef ecology and sediment generation. However, the relevance of this sediment for shoreline maintenance probably diverges with each producer group, with parrotfish-derived sediment a more appropriate size fraction to potentially contribute to local island shorelines.

Influence of bleaching agents on the color change and translucency of resin matrix ceramics

OBJECTIVE

The aim of this study was to investigate the color change, translucency, and whiteness index of three different resin matrix ceramics and a resin composite subjected to different bleaching agents.

MATERIALS AND METHODS

Twenty disc-shaped specimens (A2 shaded) for three different resin matrix ceramic brands (Groups Ena, Ulti, and Cera) (totally 60) were prepared using the CAD/CAM technique and 20 nanofiller composite specimens (Group Comp) (A2 shaded) with the same dimensions were prepared as the control group. The color change (∆E₀₀ ), relative translucency parameter (RTP), and whiteness index (WI_D ) of the specimens initial and after different bleaching procedures (home-bleaching and office-bleaching) were calculated using ∆E₀₀ , TP₀₀ , and WI_D formulas. Two-way analysis of variance (ANOVA) and multiple comparison test with Bonferroni correction (α = .05) at the significance level of P < .05 were performed for the comparisons of ∆E₀₀ values. The RTP and WI_D values were evaluated by using repeated measures ANOVA and multiple-comparison test with Bonferroni corrections (α = .05) at the significance level of P < .05.

RESULTS

Bleaching procedure and material type were found to be significant regardless of bleaching type for RTP and WI_D values. Material type has a significant effect on the ∆E₀₀ values. The highest color change values were determined in Group Comp (P < .05).

CONCLUSIONS

Bleaching procedures significantly affected the RTP values of Groups Ulti and Cera (P < .05). ∆E₀₀ values for the resin matrix ceramics after the bleaching procedures were below the clinically acceptable values, regardless of the bleaching agent.

CLINICAL SIGNIFICANCE

Optically, materials such as resin matrix ceramics have properties different from not only enamel and dentin but also among themselves. The possible effect of bleaching agents on these materials should be considered carefully while choosing the restorative material.

Drivers of recovery and reassembly of coral reef communities

Understanding processes that drive community recovery are needed to predict ecosystem trajectories and manage for impacts under increasing global threats. Yet, the quantification of community recovery in coral reefs has been challenging owing to a paucity of long-term ecological data and high frequency of disturbances. Here we investigate community re-assembly and the bio-physical drivers that determine the capacity of coral reefs to recover following the 1998 bleaching event, using long-term monitoring data across four habitats in Palau. Our study documents that the time needed for coral reefs to recover from bleaching disturbance to coral-dominated state in disturbance-free regimes is at least 9-12 years. Importantly, we show that reefs in two habitats achieve relative stability to a climax community state within that time frame. We then investigated the direct and indirect effects of drivers on the rate of recovery of four dominant coral groups using a structural equation modelling approach. While the rates of recovery differed among coral groups, we found that larval connectivity and juvenile coral density were prominent drivers of recovery for fast growing Acropora but not for the other three groups. Competitive algae and parrotfish had negative and positive effects on coral recovery in general, whereas wave exposure had variable effects related to coral morphology. Overall, the time needed for community re-assembly is habitat specific and drivers of recovery are taxa specific, considerations that require incorporation into planning for ecosystem management under climate change.

Is Bleaching Effective in Managing Post-orthodontic White-spot Lesions? A Systematic Review

PURPOSE

White spot lesions (WSL) are common side-effects of orthodontic treatment with fixed multi-bracketed appliances. The aim of this review was to find all available literature and critically assess the evidence for the efficacy of bleaching as a method to treat or alleviate post-orthodontic WSLs in permanent teeth.

MATERIALS AND METHODS

Electronic databases were screened for relevant literature with the aid of predetermined search strategies. All types of studies, including randomised or nonrandomised controlled trials (RCTs or CCTs), prospective and retrospective studies, as well as in vitro studies were considered eligible for inclusion. The reference lists of all included articles were hand searched for additional studies. Two authors independently performed study selection, data extraction, and risk of bias assessment.

RESULTS

One RCT and 8 in vitro studies met the inclusion criteria. Seven studies were classified as having a high risk of bias while 2 in vitro studies were graded as having a moderate risk of bias. The results showed that bleaching of WSL can diminish colour disparities between carious and non-affected areas, but the certainty of the evidence was very low. The high degree of methodological heterogeneity precluded a valid interpretation of the results through pooled estimates.

CONCLUSIONS

The findings from the present systematic review could not support or refute bleaching as an effective method for management of post-orthodontic WSLs. Because most of the studies in this field are in vitro and solid scientific evidence of low risk of bias is scare, further prospective in vivo studies are necessary.

Bio-degumming of banana fibers using eco-friendly crude xylano-pectinolytic enzymes

In this study, the efficacy of xylano-pectinolytic enzymes in scouring of banana fibers has been reported. Maximum efficiency of bioscouring was recorded using xylanase and pectinase doses of 15 and 4.8 IU, respectively (produced by a bacterial isolate) at a material-to-liquor proportion of 1:25 having 8.5 pH, treatment time of 1 h, speed of 50 rpm, temperature 50 °C, 3 mM EDTA and 1% Tween-80, with maximum sugar release, enhanced fiber water absorbing power and the finest optical characteristics. Enzymatic treatment resulted in 13.27% increase in whiteness, 16.14% increase in brightness and 8.63% decrease in yellowness as compared to raw banana fibers. The bioscouring also resulted in 50% reduction in scouring chemicals, in order to achieve the similar optical characteristics as obtained by the chemically treated fibers with 100% scouring and bleaching. It decreased the consumption of environment polluting chemicals and energy. Therefore, this has proven to be an environment safe method for removing the non-cellulosic impurities. This is the first report mentioning the scouring of banana fibers using xylano-pectinolytic enzymes.

Comparative evaluation of the effect of 10%, 20%, and 30% guava seed extract on reversing compromised resin bond strength after enamel bleaching in 120 min, 10 min, and 5 min: An in vitro study

Background:

Bonding of composite with enamel and dentin gets compromised if the tooth is restored with composite immediately post bleaching. The application of antioxidants has shown to have a positive effect on it.

Aim:

The aim of this study was to evaluate and compare the effect of guava seed extract solutions in various concentrations on the shear bond strength (SBS) of composite resin to bleached enamel when applied for 5 min, 10 min, and 120 min.

Materials and Methods:

Fifty-five maxillary incisors were procured, and labial surfaces of 50 specimens were bleached with 37.5% hydrogen peroxide. These specimens were divided into 3 experimental groups: Group 1–3 comprising 15 specimens each (n = 15), and the remaining specimens were divided into two groups: Group 4 (positive control group) and Group 5 (negative control group). Groups 1–3 were further divided into 3 subgroups according to the application period of antioxidant: subgroups A, B, and C. Specimens were stored in distilled water for 24 h. SBS testing was done using the universal testing machine. Data were tabulated and subjected to statistical analysis using a three-way analysis of variance with post hoc Tukey's test.

Results:

Guava seed extract showed a complete reversal of the compromised bond strength, and promising results were seen with increased concentration.

Conclusion:

The use of antioxidants effectively reversed the compromised bond strength of bleached enamel, and an increase in the concentration of antioxidants reduces the duration of its application.

Coral bleaching patterns are the outcome of complex biological and environmental networking

Continued declines in coral reef health over the past three decades have been punctuated by severe mass coral bleaching-induced mortality events that have grown in intensity and frequency under climate change. Intensive global research efforts have therefore persistently focused on bleaching phenomena to understand where corals bleach, when and why-resulting in a large-yet still somewhat patchy-knowledge base. Particularly catastrophic bleaching-induced coral mortality events in the past 5 years have catalyzed calls for a more diverse set of reef management tools, extending far beyond climate mitigation and reef protection, to also include more aggressive interventions. However, the effectiveness of these various tools now rests on rapidly assimilating our knowledge base of coral bleaching into more integrated frameworks. Here, we consider how the past three decades of intensive coral bleaching research has established the basis for complex biological and environmental networks, which together regulate outcomes of bleaching severity. We discuss how we now have enough scaffold for conceptual biological and environmental frameworks underpinning bleaching susceptibility, but that new tools are urgently required to translate this to an operational system informing-and testing-bleaching outcomes. Specifically, adopting network models that can fully describe and predict metabolic functioning of coral holobionts, and how this functioning is regulated by complex doses and interactions among environmental factors. Identifying knowledge gaps limiting operation of such models is the logical step to immediately guide and prioritize future experiments and observations. We are at a time-critical point where we can implement new capacity to resolve how coral bleaching patterns emerge from complex biological-environmental networks, and so more effectively inform rapidly evolving ecological management and social adaptation frameworks aimed at securing the future of coral reefs.

Preparation of Bentonite/Chitosan Composite for Bleaching of Deteriorating Transformer Oil

A novel adsorbent containing chitosan (CS) and bentonite (BT) was developed by mixing, drying, and calcining, and used as an adsorbent for the efficient bleaching of deteriorating transformer oil. The effects of calcination temperature, dosage of CS, adsorbent content, adsorption temperature, and adsorption time on the bleaching capacity of transformer oil were investigated. The structure of the adsorbent was also investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and N₂ adsorption-desorption isotherm techniques. The results showed that there was only physical interaction between CS and BT; CS did transform to carbon (C) and covered the surface of BT. The specific surface area and micropore volume of the adsorbent were affected by the calcination process. The composite adsorbent offered an excellent bleaching performance. When the calcination temperature was 300 °C and dosage of CS was 5%, the composite adsorbent had the optimum bleaching properties. When the composite adsorbent content was 4%, the adsorption temperature was 50 °C and the adsorption time was 75 min, the colour number and transmittance of the deteriorating transformer oil decreased from no. 10 to no. 1 and increased from 70.1% to 99.5%, respectively.

Reversal of Compromised Bond Strength of Bleached Enamel Using Cranberry Extract as an Antioxidant: an In Vitro Study

Background and Objectives: Bleaching reduces the bond strength of enamel, if adhesive restorations are carried out immediately. Reversal of compromised bond strength of bleached enamel by application of antioxidant agents has been reported in the literature. The aim of the study is to assess the neutralizing effect of 6% cranberry (CB) solution on the bond strength of bleached enamel compared with that of 10% sodium ascorbate (SA) solution.

Materials and Methods: Enamel surfaces of 64 extracted human premolar teeth were randomly divided into four groups based on the antioxidant used. Further subgrouping was done in Groups II, III, and IV dividing each group into subgroup A and subgroup B of eight teeth each based on whether the bonding was performed immediately or after a delay of 14 days postbleaching respectively. Shear bond strength (SBS) of the specimens was measured using a Universal testing machine. The data were then tabulated and statistically analyzed using one-way ANOVA (analysis of variance) and Tukey’s post-hoc parametric tests. A p-value of <0.05 was considered statistically significant.

Results: The SBS measurements were compared among the four groups including the subgroups. The SBS was highest in the SA delayed bonding group and lowest in the bleached immediate bonding group.

Conclusion: A 10% SA solution has proven superior to 6% CB solution in the reversal of compromised bond strength following bleaching.

Influence of surface treatment on the fluorescence of composite resins subjected to in situ bleaching

OBJECTIVE

Use fluorescence analysis to evaluate the effect of polishing and surface sealant on the color of composite resin bleached with carbamide peroxide and subjected to staining.

MATERIALS AND METHODS

Forty-eight composite resin specimens (Z250/Z350XT) were fabricated. After 24 hours stored in distilled water, all specimens were submitted to in situ bleaching with 16% home peroxide for 8 hours daily for a period of 14 days. Subsequently specimens were separated in three groups according to surface treatment proposed (group 1-polishing Sof-Lex; group 2-BisCover; group 3-control). After this, all the specimens were stained with red wine. A spectrofluorometer was used to evaluate the fluorescence in two readouts (L0-after surface treatment and L1-after staining).Data were analyzed by applying ANOVA using a statistical software program.

RESULTS

No differences were shown for the factor treatment and other interactions. The lowest mean fluorescence value was found for Z350XT resin (1759.18 ± 0.13) when compared with Z250 (6863.92 ± 0.13). There was significant difference in the mean fluorescence values for all surface treatments between the two different readouts L0 (4820.93 ± 0.05) and L1 (3802.17 ± 0.05).

CONCLUSION

The results suggested that all surface treatments proposed did not influenced the results of wine staining of bleached resins when compared with the control evaluated by the fluorescence method.

CLINICAL SIGNIFICANCE

The purposes of this research was to find solutions, by means of surfaces treatment, to achieve restorations with a satisfactory and similar final aspect in relation to the teeth, and avoid discrepancies related to the esthetics and longevity of the restoration.

Difference in adsorbable organic halogen formation between phenolic and non-phenolic lignin model compounds in chlorine dioxide bleaching

Adsorbable organic halogen (AOX) is generally formed by the reaction of residual lignin in pulps with chlorine dioxide during bleaching. Lignin has a complex structure. Different functional groups and bonds are present in lignin structures. Phenolic hydroxyl is one of the important functional groups in lignin, and it significantly influences the chemical properties and reactivity. To study the effect of phenolic hydroxyl on AOX formation, vanillyl alcohol (VA) was selected as the phenolic lignin model compound, and veratryl alcohol (VE) was selected as the non-phenolic lignin model compound in this study. The kinetics of AOX formation by the reaction of VA or VE with chlorine dioxide was studied. The effects of pH, chlorine dioxide, lignin model compound concentration and reaction temperature on AOX formation are discussed. The activation energies of the reaction of VA and VE with chlorine dioxide are 16 242.47 J mol^-1 and 281.34 J mol^-1, respectively. Thus, we found that the non-phenolic lignin can react with chlorine dioxide to form AOX more easily than phenolic lignin.