First Report of Anthracnose Caused by Colletotrichum siamense on Machilus thunbergii Siebold & Zucc. in South Korea.

Machilus thunbergii Siebold & Zucc., known as Japanese bay tree, is an evergreen tree distributed widely in East Asia, including South Korea, where the species is of ecological importance. Machilus thunbergii provides habitat for wildlife species and is a common urban tree. In September 2022, anthracnose symptoms on leaves were observed in Jeju (33°26'02.4"N, 126°19'48.8"E) and Tongyeong (34°49'27.1"N, 128°24'01.8"E) in South Korea. Disease incidence on leaves of each affected tree, naturally growing in an urban forest area covering approximately 0.5 ha was approximately ~ 70 % in each study area. Anthracnose symptoms that were observed on 70 to 80% leaves per tree in each study area included orbicular or irregular, whitish-grey spots on leaves that were 1.5 to 3.0 cm in diam. In some cases where leaves were severely affected, larger blotches were formed, leading to bleaching symptoms and eventually defoliation. For pathogen isolation, two or three leaves showing anthracnose symptoms from each of the 15 trees were randomly selected and brought to the laboratory. Fungal isolations were then directly made by transferring spores from acervuli that developed on diseased leaves onto potato dextrose agar (PDA) media. Cushion shaped acervuli filled with salmon to orange-colored conidial masses were produced on media approximately two weeks after the incubation at 25 ± 1°C with a photoperiod of 12 h. Conidia were single celled, hyaline, cylindrical with rounded ends, smooth walls, 13.7 to 18.1 µm long and 3.1 to 4.5 µm wide (n=30). Among 15 cultures that were successfully isolated, 10 isolates were retained based on culture characteristics, and two randomly selected monoconidial cultures were deposited in the culture collection (CDH) of the Chungnam National University, Republic of Korea (Accession No. CDH057-58). Two isolates selected, CDH057 and CDH058, were subjected to identification, and this was achieved based on multiplesequence comparisons using on internal transcribed spacer regions of rDNA (ITS1 and ITS2), partial sequences of actin (ACT) and ß-tubulin (TUB2) gene regions amplified using ITS1F / ITS4, ACT-512F / ACT-783R and T1 / Bt2b, respectively (Weir et al. 2012). The representative sequence data were deposited in GenBank under the accession numbers OR473277 and OR473278 for the ITS, OR480772 and OR480773 for ACT, and OR480774 and OR480775 for TUB2. The resulting sequences were further used for a phylogenetic analysis based on the maximum likelihood method using a concatenated dataset of the ITS, ACT and TUB2 gene sequences for Colletotrichum species in the C. gloeosporioides clade. The results showed that the pathogen isolated in this study clustered with Colletotrichum siamense (Vouchered specimens: MFLU 090230, COUFPI291, and COUFPI294) (Prihastuti et al. 2009). Sequence comparisons revealed that the isolates obtained in this study differed from the type species of C. siamense (MFLU 090230; FJ972613 for ITS, FJ 907423 for ACT, FJ907438 for TUB2) at 2 of 258 bp (∼0.8%) and 6 of 387 bp (∼1.6%) in the ACT and TUB2 sequences, respectively, while the ITS was identical to the type species. For pathogenicity tests, a total of ten three-year-old seedlings of M. thunbergii were used. The leaves of each tree were sprayed with 5 ml of conidial suspension (105 conidia/ml, isolate CDH057). Three control plants were sprayed with sterile water. After being sprayed, treated areas were sealed with a plastic bag for 24 hours to preserve humidity. Anthracnose symptoms, identical to those observed in the field, appeared five to seven days after the inoculations, while no symptoms were observed on control plants. The isolates used in the pathogenicity test were reisolated from 90% of lesions, and their identity was confirmed based on sequence comparisons, thus fulfilling Koch's postulates. Species of the C. gloeosporioides species complex include important plant pathogens, particularly C. siamense, which cause significant losses of economic and ecological relevance on a wide range of hosts (~ 100 hosts) (Talhinhas and Baroncelli 2021). Although C. fioriniae in the C. acutatum species complex, was found on M. thunbergii in South Korea (Thao et al. 2023), anthracnose associated with C. siamense on M. thunbergii has not been reported in the country. In this regard, this is the first report of anthracnose caused by C. siamense on M. thunbergii in South Korea. To effectively control the disease, more attention should be paid on the host range of the pathogen and other regions where the disease caused by the pathogen might occur in the country.

Effect of carbamide peroxide on biomechanical properties of vacuum-formed retainers: A split-mouth randomized controlled trial.

OBJECTIVE: To investigate the effect of tooth whitening on biomechanical properties of vacuum-formed retainers (VFRs). METHODS: Using a split-mouth, randomised controlled trial design, thirty participants were randomly allocated to receive whitening on either the upper or the lower arch, using 10 % carbamide peroxide for two weeks. Biomechanical properties such as hardness, tensile strength, and surface roughness were assessed two weeks after whitening was completed. RESULTS: Tensile strength of the whitening arch (mean ± SD: 40.93 ± 3.96 MPa) was significantly lower than that of the control (47.40 ± 5.03 MPa) (difference 6.47 MPa, 95 % CI 4.51 - 8.42, p < 0.001). Hardness and internal roughness of the whitening arch (VHN = 14.63 ± 2.29 N/mm2 and Ra = 1.33 ± 0.35 µm, respectively) were significantly greater than those of the control (12.22 ± 1.86 N/mm2 and 0.96 ± 0.29 µm, respectively) (differences 2.41 N/mm2, 95 % CI 1.56 - 3.25, p < 0.001 and 0.37 µm, 95 % CI 0.23 - 0.51, p < 0.001, respectively). The whitening arch showed greater tooth colour change (ΔE = 6.00 ± 3.32) than the control (ΔE = 2.50 ± 1.70) (difference = 3.50, 95 % CI 2.43 - 4.56, p < 0.001). CONCLUSIONS: Based on this short-term study, marked tooth colour change was achieved by whitening with VFRs as the whitening trays, but this changed the VFRs' biomechanical properties, including a decrease in tensile strength and an increase in hardness and internal roughness. CLINICAL SIGNIFICANCE: The application of carbamide peroxide in VFRs may compromise their mechanical properties.

Effect of Calcium Hydroxide and Antioxidant Agents Filling the Pulp Chamber after Internal Bleaching.

To evaluate the effect of calcium hydroxide (CH), sodium ascorbate (SA) and sodium thiosulfate (ST) filling the pulp chamber on color stability and longevity of teeth after internal bleaching. Crowns of bovine incisors were submitted to internal bleaching and divided into groups according the material used in the pulp chamber: Control, CH, SA, ST. Each group was divided into two subgroups according to the time to perform restorative procedures (7 or 15 days). Color measurement was performed with a spectrophotometer at nine periods. The darkening (ΔE) values were calculated. The Mann-Whitney test was used to statistically analyze the data (p ⟨ 0.05). After bleaching, ΔE values were higher than 3.5, showing that the procedure was effective. After 24 hours, no difference was observed between groups. After 7 days, SA showed higher ΔE than the control group (p ⟨ 0.05). CH and TS did not differ from the control group. In restorations performed after 7/15 days, SA group showed higher values of darkening after 1 and 4 months than the control group (p ⟨ 0.05). SA induced perceptible darkening after bleaching and should not be used to fill the pulp chamber. ST and CH show color stability and longevity after 12 months.

Investigating the Effect of Internal Bleaching With 10% Carbamide Peroxide on the Color Change of Three Types of Common Endodontic Sealers.

Background and purpose Color change caused by materials used for endodontic treatment is an important clinical issue. The current research examined the impact of internal bleaching with 10% carbamide peroxide on discolored teeth resulting from various types of sealers. Materials and methods In this study, 36 anterior teeth were cut from 1 mm beneath the cementoenamel junction (CEJ), and the samples were divided into three groups of 12. Then, AH26 (Tulsa Dental, Tulsa, OK), Endofill (Herpo Produtos Dentários Ltda, Petrópolis, Brazil), and AH Plus (Dentsply DeTrey, Konstanz, Germany) color change potential sealers were placed inside the pulp chamber. The cervical access cavity was covered with a thin layer of glass ionomer. After one month, the material was removed, and bleaching was done with 10% carbamide peroxide. The color of the samples was measured by a spectrophotometer before bleaching, one week after bleaching, and one week after bleaching again. The data were subjected to statistical analysis using the Statistical Package for Social Sciences (SPSS) software version 16 (IBM SPSS Statistics, Armonk, NY), with a significance level set at P<0.05. Results The results showed that the factor of time and material used and the opposing effect of these two on the amount of L and ΔE were statistically significant (P<0.05). After one to two weeks of internal bleaching, all groups showed some degree of reduction in sealer-induced discoloration. In addition, in all groups, the largest difference in L was related to the difference in L0 and L2 (before bleaching and one week after bleaching again), and the lowest difference was related to the difference in L0 and L1. Also, the highest ΔE(T0,T1) belonged to the Endofill group, and this significantly differed from the AH26 group. AH26 showed the lowest value of ΔE(T0,T1), and after two weeks, the ΔE of all groups was higher than the clinically observable limit. The highest ΔE(T2,T0) among the groups belonged to the Endofill group. The ΔE(T2,T0) of AH26 and Endofill was significantly higher than AH Plus. Among all ΔE values, the AH Plus group had the lowest values. Conclusion Color change caused by Endofill and AH26 sealers showed a better response to internal bleaching than the AH Plus sealer.

Unique high-temperature tolerance mechanisms of zoochlorellae Symbiochlorum hainanensis derived from scleractinian coral Porites lutea.

Global warming is a key issue that causes coral bleaching mainly because of the thermosensitivity of zooxanthellae. Compared with the well-studied zooxanthellae Symbiodiniaceae in coral holobionts, we rarely know about other coral symbiotic algae, let alone their thermal tolerance. In this study, a zoochlorellae, Symbiochlorum hainanensis, isolated from the coral Porites lutea, was proven to have a threshold temperature of 38°C. Meanwhile, unique high-temperature tolerance mechanisms were suggested by integrated transcriptomics and real-time quantitative PCR, physiological and biochemical analyses, and electron microscopy observation. Under heat stress, S. hainanensis shared some similar response strategies with zooxanthellae Effrenium sp., such as increased ascorbate peroxidase, glutathione peroxidase, superoxide dismutase activities and chlorophyll a, thiamine, and thiamine phosphate contents. In particular, more chloroplast internal layered structure, increased CAT activity, enhanced selenate reduction, and thylakoid assembly pathways were highlighted for S. hainanensis's high-temperature tolerance. Notably, it is the first time to reveal a whole selenate reduction pathway from SeO42- to Se2- and its contribution to the high-temperature tolerance of S. hainanensis. These unique mechanisms, including antioxidation and maintaining photosynthesis homeostasis, efficiently ensure the high-temperature tolerance of S. hainanensis than Effrenium sp. Compared with the thermosensitivity of coral symbiotic zooxanthellae Symbiodiniaceae, this study provides novel insights into the high-temperature tolerance mechanisms of coral symbiotic zoochlorellae S. hainanensis, which will contribute to corals' survival in the warming oceans caused by global climate change. IMPORTANCE: The increasing ocean temperature above 31°C-32°C might trigger a breakdown of the coral-Symbiodiniaceae symbioses or coral bleaching because of the thermosensitivity of Symbiodiniaceae; therefore, the exploration of alternative coral symbiotic algae with high-temperature tolerance is important for the corals' protection under warming oceans. This study proves that zoochlorellae Symbiochlorum hainanensis can tolerate 38°C, which is the highest temperature tolerance known for coral symbiotic algae to date, with unique high-temperature tolerance mechanisms. Particularly, for the first time, an internal selenium antioxidant mechanism of coral symbiotic S. hainanensis to high temperature was suggested.

Effects of bleaching on oxygen dynamics and energy metabolism of two Caribbean coral species.

As mass coral bleaching events become more frequent, it is increasingly important to elucidate the factors underlying coral susceptibility and survival. We measured photosynthesis, respiration, and O2 concentration at the coral tissue surface, Symbiodiniaceae genotypes, and energy metabolic enzyme activities in Agaricia agaricites and Orbicella franksi throughout experimentally-induced thermal bleaching (+3 °C). A. agaricites colonies started to bleach two days into the thermal treatment and were fully bleached between Days 19-31. In contrast, O. franksi colonies only started to bleach on Day 12 and five colonies fully bleached between Days 24-38 while the remining three colonies took up 55 days. Both species experienced decreased photosynthesis and respiration rates as bleaching progressed. As a result, daytime O2 concentration at the coral surface shifted from hyperoxia in unbleached corals to normoxia in partially bleached corals, and to near hypoxia in fully bleached corals. Additionally, nighttime tissue surface O2 concentration shifted from hypoxia to normoxia, likely resulting from decreased symbiotic algae density, respiration, and photosynthates that fuel coral aerobic respiration. Genetic profiling of internal transcribed spacer 2 (ITS2) revealed differences in Symbiodiniaceae clade proportions between control and bleached colonies. Activity levels of energy metabolic enzymes did not significantly vary between control and bleached A. agaricites, but malate dehydrogenase and strombine dehydrogenase activities were significantly higher in bleached O. franksi colonies compared to controls. These differences were driven by the three O. franksi colonies that took the longest to bleach and contained >98 % Durusdinium sp. D1. The shifts in O2 dynamics within the microhabitat of bleached corals may have important implications for the metabolism of the coral holobiont while the changes in Symbiodiniaceae ITS2 profile and the upregulation of energy metabolic enzymes identify a potential factor contributing to bleaching dynamics.

Research progress on invasive cervical resorption / 口腔疾病防治

@#Tooth absorption can be divided into physiological absorption and pathological absorption. Root absorption of mature deciduous teeth is physiological absorption. Pathological absorption includes internal absorption and external absorption. Internal absorption, also known as intramedullary absorption, includes inflammatory absorption and alternative absorption. External tooth absorption originates from the outer surface of the root or the neck of the tooth and can be divided into inflammatory absorption, alternative absorption, pressure resorption and invasive cervical resorption. Invasive cervical resorption (ICR) is pathological damage caused by many factors, which usually begins in the cemento-enamel junction and extends peripherally or horizontally in the dentin. It hardly invades the pulp. Orthodontic devices, trauma, bleaching, systemic diseases, and the use of certain medications can all lead to invasive cervical resorption. The clinical manifestations of ICR are usually asymptomatic or not obvious, and most of which are found in imaging examinations. Because caries and internal absorption are often misdiagnosed through plain apical radiography, cone beam computed tomography (CBCT) can help to better understand the situation of invasive cervical resorption. Because the pathogenesis and etiology of invasive cervical resorption are not fully understood, clinical negligence and inadequate treatment of invasive cervical resorption can even cause unnecessary tooth loss. This article reviews the latest research progress on the histopathologic features, pathogenic mechanism, susceptibility factors, diagnosis and treatment of ICR, with special emphasis on susceptibility factors and their mechanisms.

Intracoronal tooth bleaching - A review and treatment guidelines.

Intracoronal bleaching is a minimally invasive procedure that was introduced into dentistry in the 19th century. The role of that procedure in enhancing the colour of teeth subjected to internal discolouration while being conservative made it extremely popular amongst dental professionals. Different materials and techniques have been utilized over the years attempting to obtain predictable long-term results while minimizing any associated risks. Contemporarily, bleaching agents are mainly based on peroxide-releasing compounds in different formulations and delivery systems. Different theories have been formulated on the bleaching mechanism of such agents, but the exact mechanism is yet to be proven. The effect of hydrogen peroxide-based bleaching agents on the organic structure of enamel and dentine has been extensively investigated to address the effects of bonding of resin-based restorative materials to hard tooth structure. Multiple case reports raised a concern about the contribution of intracoronal bleaching in developing invasive root resorption. Modification of intracoronal bleaching techniques was thus necessary to address such concerns. This review will provide a summary of the important aspects of intracoronal bleaching, focusing on how it applies to the contemporary clinical setting. © 2023 Australian Dental Association.

Marine heatwave duration and intensity interact to reduce physiological tipping points of kelp species with contrasting thermal affinities.

BACKGROUND AND AIMS: Marine heatwaves (MHWs) are widely-recognised as pervasive drivers of ecosystem change, yet our understanding of how different MHW properties mediate ecological responses remains largely unexplored. Understanding MHW impacts on foundation species is particularly important, given their structural role in communities and ecosystems. METHODS: We simulated a series of realistic MHWs with different levels of intensity (Control: 14°C, Moderate: 18°C, and Extreme: 22°C) and duration (14 or 28 days) and examined responses of two habitat-forming kelp species in southwest United Kingdom (UK). Here, Laminaria digitata reaches its trailing edge and is undergoing a range contraction, whereas L. ochroleuca reaches its leading edge and is undergoing a range expansion. KEY RESULTS: For both species, sub-lethal stress responses induced by moderate intensity MHWs were exacerbated by longer duration. Extreme intensity MHWs caused dramatic declines in growth and photosynthetic performance, and elevated bleaching, which were again exacerbated by longer MHW duration. Stress responses were most pronounced in L. ochroleuca, where almost complete tissue necrosis was observed by the end of the long duration MHW. This was unexpected due to the greater thermal safety margins assumed with leading edge populations. It is likely that prolonged exposure to sub-lethal thermal stress exceeded a physiological tipping point for L. ochroleuca, presumably due to depletion of internal reserves. CONCLUSIONS: Overall, our study showed that exposure to MHW profiles projected to occur the region in the coming decades can have significant deleterious effects on foundation kelp species, regardless of their thermal affinities and location within respective latitudinal ranges, which would likely have consequences for entire communities and ecosystems.

Chemical, morphological and microhardness analysis of coronary dentin submitted to internal bleaching with hydrogen peroxide and violet LED.

BACKGROUND: Violet LED has been used for internal bleaching, however its implications on coronary dentin composition are unclear. The present study aims to evaluate the effect of bleaching with violet LED, either associated with 35 % hydrogen peroxide or not, on microhardness, chemical composition, and morphological characteristics of coronal dentin. METHODS: Thirty maxillary canines were selected to obtain 30 blocks of coronal dentin, distributed in 3 groups (n = 10): 35 % hydrogen peroxide (HP); violet LED (LED); HP 35 % + LED, (HP+LED). The chemical analysis was performed by FTIR and the morphological evaluation of the dentin structure by confocal laser scanning microscopy before (T0) and after treatment (T1). The microhardness analysis was performed by microdurometer after bleaching. The data were submitted to repeated measures ANOVA test (P> 0.05). RESULTS: The intensity of the inorganic peaks decreased after bleaching for all groups (P = 0.003). There was an increase in the organic peak intensity after bleaching with HP, a decrease for LED, while HP+LED did not change the intensity (P = 0.044). Moreover, the inorganic/organic ratio decreased for HP (P = 0.022), while for LED and HP+LED there was no significant changes (P>0.05). HP and HP+LED showed lower microhardness values compared to LED (P< 0.05). Regarding morphological changes, an increase in the perimeter of the dentinal tubules was found for all groups, with the smallest increase being observed for LED. CONCLUSION: HP bleaching decreased the chemical stability and microhardness of the coronal dentin, while the violet LED treatments had no significant impact on dentin stability. In all groups, there was an increase in exposure of the dentinal tubules after bleaching, which was less pronounced with the violet LED bleaching.

Mesophotic coral bleaching associated with changes in thermocline depth.

As global temperatures continue to rise, shallow coral reef bleaching has become more intense and widespread. Mesophotic coral ecosystems reside in deeper (30-150 m), cooler water and were thought to offer a refuge to shallow-water reefs. Studies now show that mesophotic coral ecosystems instead have limited connectivity with shallow corals but host diverse endemic communities. Given their extensive distribution and high biodiversity, understanding their susceptibility to warming oceans is imperative. In this multidisciplinary study of an atoll in the Chagos Archipelago in the central Indian Ocean, we show evidence of coral bleaching at 90 m, despite the absence of shallow-water bleaching. We also show that the bleaching was associated with sustained thermocline deepening driven by the Indian Ocean Dipole, which might be further enhanced by internal waves whose influence varied at a sub-atoll scale. Our results demonstrate the potential vulnerability of mesophotic coral ecosystems to thermal stress and highlight the need for oceanographic knowledge to predict bleaching susceptibility and heterogeneity.

Guided Endodontic Treatment for Calcified Central Incisor with Discoloration, a Conservative Approach Preserving Incisal Edge: A Case Report.

Pulp canal obliteration (PCO) in calcified teeth presents a challenge for endodontic treatment, especially when accompanied by discoloration. Guided endodontic access (GEA) has emerged as an advanced method for root canal therapy (RCT) in such cases. This case report describes the successful treatment of a calcified maxillary central incisor with discoloration using GEA. A 32-year-old female with a history of dental trauma presented with discoloration in the left maxillary central incisor that did not respond to external bleaching. Clinical examination revealed a pulpless infected canal with asymptomatic apical periodontitis. Cone-beam computed tomography (CBCT) and intraoral scanning were utilized to create a three dimensional (3D) template, enabling minimally invasive access preparation through the palatal aspect. The RCT was performed in a single visit, followed by tooth whitening using hydrogen peroxide. At 18 months follow-up, the tooth was asymptomatic, and the apical lesion was healed. GEA offers a predictable and conservative approach, preserving tooth structure and providing enhanced long-term prognosis for teeth with calcified canals and discoloration.

Dual-modal identification of jadeite based on optical coherence tomography images and Raman spectral features.

Low-quality jadeite is often subjected to bleaching, filling, and dyeing to improve its texture and consequently increase its value. In this study, natural jadeite, bleached and filled jadeite, and dyed jadeite were investigated by combining Raman spectroscopy and optical coherence tomography (OCT). The results show that jadeite composition can be identified from Raman peaks around 205, 377, 700, and 1040c m -1. The presence of epoxy filler can be detected from Raman peaks at 1113, 1187, and 1609c m -1, among which the features of 1113 and 1609c m -1 are particularly significant. Dyed jadeite exhibits a pronounced fluorescence background in its Raman spectrum due to the injected dye. After noise reduction, texture vectors representing the texture of bleached or dyed jadeite can be obtained from OCT images. These vectors differ from the corresponding texture vector of natural jadeite. Most processed jadeites have relatively low texture vector intensities due to particle reduction and texture damage during processing. However, the texture vector strengths of jadeites can be increased through internal silting.

Necrotic Pulp With Crown Discoloration Associated With Orthodontic Treatment: A Case Report.

Orthodontic treatment may have iatrogenic consequences for the pulpal tissue. This study describes the endodontic treatment and internal bleaching that were used to treat a necrotic pulp with internal resorption caused by the dentist. This happened to the pulpal tissue after it had been treated with orthodontics. To prevent such iatrogenic consequences for pulpal tissue during orthodontic treatment, it is essential to maintain frequent radiological follow-ups. Regular radiographic examinations can help identify any potential complications early on, allowing for timely intervention and treatment. Additionally, employing light orthodontic force can help minimize the risk of trauma to the pulpal tissue, reducing the likelihood of necrosis and internal resorption.

Effect of Different Protective Bases on pH Changes and Hydrogen Peroxide Microleakage During Intracoronal Bleaching.

Objectives: This study aimed to evaluate the pH changes and penetration of hydrogen peroxide into radicular dentin when different protective bases were used with and without a bonding agent. Materials and Methods: In this in-vitro experimental study, 70 single-rooted bovine teeth were instrumented and obturated with gutta-percha. The gutta-percha was removed 3mm below the cementoenamel junction (CEJ) and the teeth were divided into seven groups (n=10). In each group, 2mm base (1mm apical to the CEJ) was applied as follows: TheraCal LC, TheraCal LC plus SE Bond, Lime-Lite, Lime-Lite plus SE Bond, Ionoseal, Ionoseal plus SE Bond, and resin-modified glass ionomer (RMGI). The teeth were placed in vials containing distilled water, and pH values and molar concentration of the medium surrounding the teeth were recorded immediately after internal bleaching with 35% hydrogen peroxide. The pH values were also recorded at 1, 7, and 14 days following renewal of the medium. Data were analyzed with t-test, one-way ANOVA, and Kruskal-Wallis test. Results: After bleaching, the medium pH became acidic in all groups. There were no significant differences among groups in the mean pH of the medium after bleaching (P=0.189). Moreover, there were no significant differences among the study groups with respect to hydrogen peroxide concentration (P=0.895). Conclusion: Intra-orifice barriers such as light-cure resin-modified calcium hydroxide, light-cure resin-reinforced glass ionomer, and light-cure calcium silicate can be as effective as RMGI in providing coronal seal during intracoronal bleaching.

The Effect of 10% Carbamide Peroxide Dental Bleaching on the Physical Properties of Invisalign Aligners: An In Vitro Study.

The high aesthetic demands of patients have increased their requests to align their teeth using clear aligners, including Invisalign. Patients also want to have their teeth whitened for the same purpose; the use of Invisalign as a bleaching tray at night has been reported in few studies. However, whether 10% carbamide peroxide affects the physical properties of Invisalign is unknown. Therefore, the objective of this study was to evaluate the effect of 10% carbamide peroxide on the physical properties of Invisalign when used as a bleaching tray at night. Twenty-two unused Invisalign aligners (Santa Clara, CA, USA) were used to prepare 144 specimens to test their tensile strength, hardness, surface roughness, and translucency. The specimens were divided into four groups: a testing group at baseline (TG1), a testing group after application of bleaching material at 37 °C for 2 weeks (TG2), a control group at baseline (CG1), and a control group after immersion in distilled water at 37 °C for 2 weeks (CG2). Statistical analysis was conducted using a paired t-test, Wilcoxon signed rank test, independent samples t-test, and Mann-Whitney test to compare samples in CG2 to CG1, TG2 to TG1, and TG2 to CG2. Statistical analysis showed no statistically significant difference between the groups for all physical properties, except for hardness (p-value < 0.001) and surface roughness (p-value = 0.007 and p-value < 0.001 for the internal and external surface roughness, respectively), which revealed a reduction in hardness values (from 4.43 ± 0.86 N/mm2 to 2.2 ± 0.29 N/mm2) and an increase in surface roughness (from 1.6 ± 0.32 Ra to 1.93 ± 0.28 Ra and from 0.58 ± 0.12 Ra to 0.68 ± 0.13 Ra for the internal and external surface roughness, respectively) after 2 weeks of dental bleaching. Results showed that Invisalign can be used for dental bleaching without excessive distortion or degradation of the aligner material. However, future clinical trials are required to further assess the feasibility of using Invisalign for dental bleaching.

The Effect of Calcium Silicate-Based Materials on Tooth Discoloration and Evaluation of Color Change After Bleaching Treatment: A Spectrophotometric Study.

PURPOSE: To evaluate tooth discoloration after the use of calcium silicate-based materials and to examine the effect of internal bleaching on tooth discoloration. MATERIALS AND METHODS: The specimens were randomly divided into two experimental groups (n = 45) and a control group (n = 6). Cavities were filled with ProRoot MTA (Dentsply) in Group 1 and Biodentine (Septodont) in Group 2. Color measurements were taken with a spectrophotometer before and after the application of materials at 1 week and then at 13, and 6 months. After 6 months, Groups 1 and 2 were divided into three subgroups according to internal bleaching techniques. All color change ratios and lightness differences were calculated using the CIE L*a*b* system. Data were analyzed using repeated ANOVA and the Kruskal-Wallis test (P = .05). RESULTS: There were statistically significant differences between Groups 1 and 2 at all time intervals (P < .05). Group 1 showed more discoloration than Group 2 (P < .05). There were no significant differences between the bleaching agents (P > .05). Additionally, specimens in both groups became lighter than their initial color (P < .05). CONCLUSION: Teeth treated with ProRoot MTA exhibited darkening at 1 week that increased over time, whereas those treated with Biodentine maintained the lightness for 6 months.

Faceta Direta de Resina Composta utilizando Pigmentos Opacificadores para Reabilitação Estética Anterior de Dente Escurecido: Relato de Caso / Direct Composite Resin Veneer using Opacifying Pigments for Anterior Aesthetic Rehabilitation of Discolored Teeth: Case Report

O tratamento estético de dentes com alteração de cor é um grande desafio na Odontologia Restauradora. Nesse sentido, a utilização de técnicas de estratificação com resina composta associada ao uso de pigmentos opacificadores permite que seja possível restaurar por meio de uma técnica direta, que resulta em um menor desgaste da estrutura dental durante o preparo. Dessa forma, o presente trabalho apresenta um caso clínico de faceta direta de resina composta utilizando associação de três pigmentos opacificadores. Paciente do sexo masculino, 54 anos, procurou atendimento apresentando alteração de cor severa do dente 21, relato de trauma dental, tratamento endodôntico e contraindicação de novo protocolo de clareamento interno, sendo sugerido, como plano de tratamento, a restauração direta com resina composta. Para a confecção da faceta direta de resina, foi utilizada uma mistura de três opacificadores na consistência fluida. Para verificar o valor da camada aplicada da mistura, foram feitas fotografias em preto e branco. A estratificação prosseguiu com camadas de resina translúcida para a base palatina, resina opaca de dentina e resina acromática translúcida para o esmalte. Como resultado, constatou-se a função e eficácia do uso da associação de pigmentos opacificadores na resolução do caso, em seguida, foi realizada uma reavaliação após 30 dias e 7 meses do procedimento restaurador, quando verificou-se a estabilidade de cor da restauração. Concluiu-se, portanto, que a utilização da técnica de estratificação de resinas compostas associada a utilização de pigmentos opacificadores traz resultados estéticos satisfatórios e favoráveis por meio de uma técnica direta, realizada em sessão clínica única e com alta previsibilidade.

The esthetic treatment of teeth with discoloration is a major challenge in restorative dentistry. In this sense, the use of composite resin veneering techniques associated with the use of opacifying stains allows restorations to be made using a direct technique, which results in less wear to the tooth structure during preparation. Thus, the present study presents a clinical case of a direct composite resin veneer using an association of three opacifying pigments. A 54-year-old male patient presented with severe color change on the central upper left incisor, a report of dental trauma, endodontic treatment, and contraindication for a new internal bleaching protocol. In order to make the direct resin veneer, a mixture of three opacifiers in a fluid consistency was used. To check the value of the applied layer of the mixture, black and white photographs were taken. Layering proceeded with translucent resin layers for the palatal base, opaque dentin resin and translucent achromatic resin for the enamel. As a result, the function and efficacy of the use of the association of opacifying pigments was verified in the resolution of the case. A reevaluation was performed 30 days and 7 months after the restorative procedure, when the color stability of the restoration was verified. This case allows to conclude that using composite resin layering technique associated with the use of opacifying pigments brings satisfactory and favorable aesthetic results through a direct technique, performed in a single clinical session and with high predictability.

10†kHz Shifted-Excitation Raman Difference Spectroscopy with Charge-Shifting Charge-Coupled Device Read-Out for Effective Mitigation of Dynamic Interfering Backgrounds.

In this work we demonstrate an advanced concept of a charge-shifting charge-coupled device (CCD) read-out combined with shifted excitation Raman difference spectroscopy (SERDS) capable of operating at up to 10 kHz acquisition rates for the effective mitigation of fast-evolving interfering backgrounds in Raman spectroscopy. This rate is 10-fold faster than that achievable with an instrument we described previously and is overall 1000-fold faster than possible with conventional spectroscopic CCDs capable of operating at up to ∼10 Hz rates. The speed enhancement was realized by incorporating a periodic mask at the internal slit of an imaging spectrometer permitting a smaller shift of the charge on the CCD (8 pixels) to be required during the cyclic shifting process compared with the earlier design which employed an 80-pixel shift. The higher acquisition speed enables the more accurate sampling of the two SERDS spectral channels, enabling it to effectively tackle highly challenging situations with rapidly evolving interfering fluorescence backgrounds. The performance of the instrument is evaluated for heterogeneous fluorescent samples which are moved rapidly in front of the detection system aiming at the differentiation of chemical species and their quantification. The performance of the system is compared with that of the earlier 1 kHz design and a conventional CCD operated at its maximum rate of 5.4 Hz as previously. In all situations tested, the newly developed 10 kHz system outperformed the earlier variants. The 10 kHz instrument can benefit a number of prospective applications including: disease diagnosis where high sensitivity mapping of complex biological matrices in the presence of natural fluorescence bleaching restricts achievable limits of detection; accurate data acquisition from moving heterogeneous samples (or moving a handheld instrument in front of the sample during data acquisition) or data acquisition under varying ambient light conditions (e.g., due to casting shadows, sample or instrument movement). Other beneficial scenarios include monitoring rapidly evolving Raman signals in the presence of largely static background signals such as in situations where a heterogeneous sample is moving rapidly in front of a detection system (e.g., a conveyor belt) in the presence of static ambient light.

One-year clinical observation of the effect of internal bleaching on pulpless discolored teeth.

OBJECTIVES: This study aimed to observe the color rebound and rebound rates of non-pulp discolored teeth within 1 year after routine internal bleaching to guide clinical practice and prompt prognosis. METHODS: In this work, the efficacy of bleaching was observed in 20 patients. The color of discolored teeth was measured by using a computerized colorimeter before bleaching; immediately after bleaching; and at the 1st, 3rd, 6th, 9th, and 12th months after bleaching. The L*, a*, and b* values of the color of cervical, mesial, and incisal parts of the teeth were obtained, and the color change amounts ΔE*, ΔL*, Δa*, and Δb* were calculated. The overall rebound rate (P*) and the color rebound velocity (V*) were also analyzed over time. RESULTS: In 20 patients following treatment, the average ΔE* of tooth color change was 14.99. After bleaching, the neck and middle of the teeth ΔE* and ΔL* decreased in the 1st, 3rd, 6th, 9th, and 12th months, and the differences were statistically significant. Meanwhile, from the 9th month after bleaching, the rebound speed was lower than that in the 1st month, and the difference was statistically significant. The incisal end of the tooth ΔE* and ΔL* decreased in the 6th, 9th, and 12th months after bleaching, and the differences were statistically significant. No significant difference was found in the rebound speed between time points. However, this rate settled after the 9th month, with an average color rebound rate of 30.11% in 20 patients. CONCLUSIONS: The results indicated that internal bleaching could cause a noticeable color change on pulpless teeth. The color rebound after bleaching was mainly caused by lightness (L*), which gradually decreased with time, and it was slightly related to a* and b*. The color of the teeth after internal bleaching rebounded to a certain extent with time, but the color rebound speed became stable from the 9th month. Clinically, secondary internal bleaching can be considered at this time according to whether the colors of the affected tooth and the adjacent tooth are coordinated and depending on the patient's needs.