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.

Dental and composite resin discoloration induced by different hydraulic calcium silicate-based cements: two-year in vitro assessment.

Few long-term studies assess the discoloration induced by hydraulic calcium silicate-based cement on dental structures. In addition, as far as we know, no long-term study has assessed the discoloration induced by these cement on composite resin. This in vitro study aimed to assess, during a period of two years, the discoloration potential of different hydraulic calcium silicate-based cements (hCSCs) on the enamel/dentin structure and composite resin restoration. A total of 40 enamel/dentin discs were obtained from bovine incisors, and 40 composite resin discs (10 mm in diameter × 2 mm thick) were fabricated. A 0.8 mm-deep cavity was made in the center of each disc and filled with the following hCSCs (n=10): Original MTA (Angelus); MTA Repair HP (Angelus); NeoMTA Plus (Avalon); and Biodentine (Septodont). An initial color measurement was performed (T0 - baseline). After 7, 15, 30, 45, 90, 300 days, and two years, new color measurements were performed to determine the color (ΔE00), lightness (ΔL'), chroma (ΔC'), hue differences (ΔH'), and whiteness index (WID). For enamel/dentin, the ΔE00 was significant among groups and periods (p<0.05). NeoMTA Plus had the greatest ΔE00. The NeoMTA Plus group had the greatest ΔE00 after two years for composite resin. Significant reduction in lightness was observed for all groups after two years (p<0.05). The most significant WID values were observed after 30 days for Biodentine (enamel/dentin) and MTA Repair HP groups (composite resin) (p<0.05). The hCSCs changed the colorimetric behavior of both substrates, leading to greater darkening over time. The Bi2O3 in the Original MTA seems relevant in the short periods of color change assessment.

Pica caused by emetic drugs in laboratory rats with kaolin, gypsum, and lime as test substances.

Pica refers to eating nonfood substances. The pica behavior has been the focus of attention in physiological and pharmacological studies, because its consumption is a good marker of nausea in laboratory rats, which cannot vomit due to neuroanatomical reasons. Almost all pica studies with rats have used kaolin clay pellets as nonfood substances. The present study primarily aimed to explore an alternative (or more suitable) substance to kaolin for detection of nausea induced by emetic drugs. Two calcium compounds, gypsum and lime, were evaluated in this study. An injection of lithium chloride (LiCl) increased pica behavior not only in the rats given kaolin but also in the rats given gypsum, suggesting that gypsum consumption could be used as an indicator of nausea. However, its sensitivity was no greater than that of kaolin consumption. In addition, lime is not a useful marker for nausea because the size of pica was small in the LiCl-injected rats, and did not differ from the control in the cisplatin-injected rats. In short, the superiority of kaolin as a test substance for nausea could not be overturned. However, the fact that nauseous rats displayed pica behavior with gypsum and lime refutes the claim that aluminosilicate, the main component of kaolin, is the critical determinant of emetic-caused pica in laboratory rats.

Coronal discoloration induced by calcium silicate-based cements used in full pulpotomy in mature permanent molars: a randomized clinical trial.

OBJECTIVES: This study aimed to randomly compare in vivo coronal discoloration at 6 and 12 months after full pulpotomy in mature permanent molars using MTA, Biodentine, and TotalFill and to investigate the effect of variables such as remaining buccal wall thickness and time to achieve hemostasis. MATERIALS AND METHODS: One hundred eight teeth that met the inclusion criteria received full pulpotomy and were randomly divided into 3 groups via a block randomization technique according to the calcium silicate cement (CSC): ProRoot WMTA, TotalFill, or Biodentine. Assessment of tooth color was carried out using a spectrophotometric device (VITA Easyshade Compact) after composite placement (T0), at 6- and 12-month follow-up. Buccal wall thickness and time to hemostasis were recorded. The primary outcome measure (color change ΔE) was calculated, and the results were analyzed by three-way ANOVA and crosstabulations in relation to material type and effect of variables. RESULTS: Four cases were excluded after pulpotomy failure; 81 teeth were evaluated at 6 months and 95 teeth at 12 months. All CSCs caused tooth discoloration (defined as ΔE > 3.7); MTA significantly caused the highest color change at 6- and 12-month follow-up (76% (19/25) and 87.5% (28/32), respectively) compared to Biodentine (41% (9/22), 48% (13/27)) and TotalFill (44% (15/34), 53% (19/53)) (p = 0.022, p = 0.002), while no significant difference was found between the Biodentine and TotalFill groups (p = 0.813, p = 0.8). Buccal wall thickness (above or below 2.7 mm) had a significant effect on the degree of discoloration (p = 0.004). CONCLUSIONS: The 3 CSCs caused tooth discoloration based on the threshold of ΔE > 3; the remaining buccal wall thickness was a significant factor. The use of Biodentine and TotalFill instead of MTA is encouraged to minimize discoloration. CLINICAL RELEVANCE: While experimental studies report coronal discoloration after CSCs use, clinical data is lacking. This study assessed discoloration using a spectrophotometric device. The use of materials with lower discoloration potential in pulpotomy is encouraged. TRIAL REGISTRATION: The study was registered with clinical trial registration number: NCT04346849 on 14.4.2020.

Tooth discoloration induced by apical plugs with hydraulic calcium silicate-based cements in teeth with open apices-a 2-year in vitro study.

OBJECTIVES: To assess tooth discoloration induced by different hydraulic calcium silicate-based cements (HCSCs), including effects of blood and placement method. MATERIALS AND METHODS: Eighty bovine teeth cut to a length of 18 mm (crown 8 mm, root 10 mm) were randomly assigned to 10 groups (n = 8), receiving orthograde apical plug treatment (APT). Apical plugs were 4 mm in length and made of ProRoot MTA (Dentsply), Medcem MTA (Medcem), TotalFill BC RRM Fast Set Putty (Brasseler), or Medcem Medical Portland Cement (Medcem) plus bismuth oxide (Bi2O3) with and without bovine blood. Further, orthograde (with or without preoperative adhesive coronal dentin sealing) and retrograde APT were compared. Teeth were obturated with gutta-percha and sealer, sealed with composite and stored in distilled water. Tooth color was measured on apical plug, gutta-percha/sealer, and crown surface before treatment versus 24 h, 1, 3, 6, 12, and 24 months after treatment by spectrophotometry. Color difference (ΔE) values were calculated and analyzed by Shapiro-Wilk test, ANOVA with post hoc tests, Friedman test, t test, and post hoc tests with Bonferroni correction (α = .05). RESULTS: Tooth discoloration occurred in all groups with no significant differences between HCSCs (p > .05). After 24 months, color changes were prominent on roots but insignificant on crowns. Blood contamination induced a significantly decreased luminescence (p < .05). Blood had a stronger impact on tooth color than Bi2O3. No relevant effects of retrograde placement (p > .05) or preoperative dentin sealing (p > .05) were detected. CONCLUSIONS: Apical plugs of the tested HCSCs cause discoloration of bovine roots, but not discoloration of bovine tooth crowns within a 24-month period. CLINICAL RELEVANCE: APT should be performed carefully while avoiding direct contact with the coronal dentin, and in that case no aesthetic impairments occur.

Quantifying Coronal Permanent Tooth Discoloration Caused by Different Pulpotomy Materials.

INTRODUCTION: Bioceramic materials, gray and white mineral trioxide aggregate (GMTA, WMTA), have been shown to have high rates of success in various endodontic applications. A major drawback is their tendency to discolor teeth compared to Biodentine (BD), that has been claimed not to discolor teeth. The aim of this study was to compare tooth discoloration after applying different pulpotomy base materials (BD, GMTA and WMTA). STUDY DESIGN: Forty human incisors teeth were used in this study. Coronal access was achieved by a Tungsten Carbide drill, and the pulp chambers were accessed and chemo-mechanically debrided. Each material was placed in the pulp chamber, up to the cervical sectioning level. All specimens were incubated at 37°C and 100% humidity for three months and have been evaluated before the study and weekly. Color was assessed according to the CIE L*a*b* color space system. RESULTS: ΔE of all experimental groups (GMTA, WMTA and BD) were significantly different from the control group at all time points (P<0.05). Color changes in the GMTA and WMTA groups, had no statistically significant differences, but showed higher discoloration compared to BD group in the cervical part of the crown, since week 1 (P<0.05). WMTA group showed significant discoloration in the cervical part as of week 1 (P<0.05), and gradually increased over time (Figure 2). BD group showed no significantly discoloration over time. GMTA group showed the significant discoloration at week 1 and week 14 (P<0.05). CONCLUSIONS: both GMTA and WMTA pulpotomy materials may discolor tooth structure over time in an extracted permanent anterior tooth model. When choosing bioceramic pulpotomy material, BD may be preferable in esthetic area.

Cytotoxicity and cytokine production by calcium silicate-based materials on periodontal ligament stem cells.

This study investigated the effect of three commercial calcium silicate-based materials (CSBM) on cytotoxicity and pro-and anti-inflammatory cytokines production in cultured human periodontal ligament stem cells (hPDLSCs). Culture of hPDLSCs was established and characterized. Extracts of Bio-C Sealer (Angelus, Londrina, PR, Brazil), MTA Fillapex (Angelus, Londrina, PR, Brazil) and PBS Cimmo HP (Cimmo Soluções em Saúde, Pouso Alegre, MG, Brazil) were prepared by placing cement specimens (5 x 3 mm) in culture medium. Then, the extracts were serially two-fold diluted (1, 1:2, 1:4, 1:8, 1:16) and inserted into the cell-seeded wells for 24, 48 and 72 h for MTT assays. TNF-α and IL-10 cytokines were quantified by ELISA at 24h-cell supernatants. Data were analyzed by ANOVA and Tukey's test (α = 0.05). All CSBM exhibited some cytotoxicity that varied according to extract concentration and time of evaluation. MTA Fillapex presented the highest cytotoxic effects with significant reduction of metabolic activity/cell viability when compared to Bio-C Sealer and Cimmo HP®. TNF-α was significantly upregulated by the three tested cements (p < 0.05) while only MTA Fillapex significantly upregulated IL-10 in comparison to control. Taken collectively, the results showed that PBS Cimmo HP®, Bio-C Sealer and MTA Fillapex present mild and transient cytotoxicity and slightly induced TNF-α production. MTA Fillapex upregulated IL-10 release by hPDLSCs.

The effect of different calcium silicate-based pulp capping materials on tooth discoloration: an in vitro study.

BACKGROUND: Variation in the composition of calcium silicate-based pulp capping materials could influence the discoloration potential of some of these materials, thus affecting the color and aesthetic appearance of the coronal tooth structure. Furthermore, contact with blood if hemostasis is not fully achieved may enhance this discoloration for some materials. Therefore the aim of this study was to evaluate in vitro the color change of coronal tooth structure after placing various calcium silicate-based materials in the pulp chamber in the presence or absence of blood. MEHTODS: Maxillary extracted premolars (n = 144) were sectioned and the crowns were separated from the roots. Pulp chambers were prepared to a standard size and then the tested materials (GMTA Angelus, ProRoot WMTA, Biodentine, TheraCal, and TotalFill) were placed with saline or with blood. Color change was assessed by spectrophotometry; prior to and after material placement at different time intervals of 24 h, 1 week, 1 month, 3 months, and 6 months. Color change (ΔE) values were calculated and statistically analyzed. RESULTS: In the saline groups, Biodentine caused the least color change, while GMTA and WMTA caused the highest color change which were significantly different from the others (p < 0.001), TotalFill and TheraCal caused moderate changes. Adding blood increased the ΔE overall the tested materials to various degrees. Biodentine was the most affected by the blood, while MTA groups were the least affected, followed by TotalFill and then TheraCal. The increase in ΔE was significant over time up to 3 months, after which the increase was not significant. CONCLUSIONS: Overall, WMTA and GMTA caused the most severe discoloration. In saline, Biodentine caused the least discoloration, but it was the most affected by the presence of blood, although it still caused the least discoloration similar to that observed with TotatFill. TheraCal caused moderate discoloration but more than that caused by Biodentine and TotalFill.

Cytotoxicity and cytokine production by calcium silicate-based materials on periodontal ligament stem cells

Abstract This study investigated the effect of three commercial calcium silicate-based materials (CSBM) on cytotoxicity and pro-and anti-inflammatory cytokines production in cultured human periodontal ligament stem cells (hPDLSCs). Culture of hPDLSCs was established and characterized. Extracts of Bio-C Sealer (Angelus, Londrina, PR, Brazil), MTA Fillapex (Angelus, Londrina, PR, Brazil) and PBS Cimmo HP (Cimmo Soluções em Saúde, Pouso Alegre, MG, Brazil) were prepared by placing cement specimens (5 x 3 mm) in culture medium. Then, the extracts were serially two-fold diluted (1, 1:2, 1:4, 1:8, 1:16) and inserted into the cell-seeded wells for 24, 48 and 72 h for MTT assays. TNF-α and IL-10 cytokines were quantified by ELISA at 24h-cell supernatants. Data were analyzed by ANOVA and Tukey's test (α = 0.05). All CSBM exhibited some cytotoxicity that varied according to extract concentration and time of evaluation. MTA Fillapex presented the highest cytotoxic effects with significant reduction of metabolic activity/cell viability when compared to Bio-C Sealer and Cimmo HP®. TNF-α was significantly upregulated by the three tested cements (p < 0.05) while only MTA Fillapex significantly upregulated IL-10 in comparison to control. Taken collectively, the results showed that PBS Cimmo HP®, Bio-C Sealer and MTA Fillapex present mild and transient cytotoxicity and slightly induced TNF-α production. MTA Fillapex upregulated IL-10 release by hPDLSCs.

Resumo Este estudo investigou o efeito de três materiais comerciais à base de silicato de cálcio (CSBM) na citotoxicidade e na produção de citocinas pró e antiinflamatórias em células-tronco do ligamento periodontal humano (hPDLSCs). Cultura de hPDLSCs foi estabelecida e caracterizada. Extratos de Bio-C Sealer (Angelus, Londrina, PR, Brasil), MTA Fillapex (Angelus, Londrina, PR, Brasil) e PBS Cimmo HP® (Cimmo Soluções em Saúde, Pouso Alegre, MG, Brasil) foram preparados com a colocação de espécimes dos cimentos (5 x 3 mm) em meio de cultura. Em seguida, os extratos foram diluídos (1, 1: 2, 1: 4, 1: 8, 1:16) e inseridos nos poços semeados de células para ensaio de citotoxicidade por meio de MTT por 24, 48 e 72 h. As citocinas TNF-α e IL-10 foram quantificadas por ELISA em sobrenadantes de células de 24 h. Os dados foram analisados por ANOVA e teste de Tukey (α = 0,05). Todos os CSBM exibiram alguma citotoxicidade que variou de acordo com a concentração do extrato e o tempo de avaliação. O MTA Fillapex apresentou os maiores efeitos citotóxicos com redução significativa da atividade metabólica / viabilidade celular quando comparado ao Bio-C Sealer e Cimmo HP®. O TNF-α foi regulado positivamente pelos três cimentos testados (p <0,05), enquanto apenas o MTA Fillapex regulou positivamente a liberação de IL-10 em comparação com o controle. Tomados em conjunto, os resultados mostraram que PBS Cimmo HP®, Bio-C Sealer e MTA Fillapex apresentam citotoxicidade leve e transitória e induziram a produção de TNF-α. O MTA Fillapex regulou positivamente a liberação de IL-10 por hPDLSCs.

Comparison of Postobturation Pain Experience after Apical Extrusion of Calcium Silicate- and Resin-Based Root Canal Sealers.

INTRODUCTION: This study compared the intensity of postobturation pain after unintentional apical extrusion of calcium silicate-based root canal sealers (EndoSequence BC Sealer [Brasseler USA, Savannah, GA] and Bio-C Sealer [Angelus, Londrina, PR, Brazil]) with a resin-based sealer (AH Plus; Dentsply Sirona, York, PA). METHODS: A total of 330 patients referred for root canal treatment on molar teeth with asymptomatic irreversible pulpitis were recruited. Root canals were prepared using WaveOne Gold instruments (Dentsply Sirona) in a crown-down technique and irrigated with 2% chlorhexidine gel and saline solution. Next, patients were randomly distributed into 3 groups according to the root canal sealer used (n = 110): AH Plus, BC Sealer, and Bio-C Sealer. Root canal filling was then accomplished with a vertical compaction technique. Patients presenting with an unintentional extrusion of sealers (n = 13/group) were assessed for postobturation pain experience using a visual descriptor scale ranging from 0-10 at 6-, 12-, 24-, and 48-hour and 1-week intervals after treatment. Mixed analysis of variance repeated measures were used to assess the results (α = 0.05). RESULTS: The extrusion rate was similar for all sealers (~12%). There was no significant difference in the postobturation pain results between the root canal sealers evaluated (P > .05). However, after the time interval of 12 hours, AH Plus (P = .04073) and Bio-C Sealer (P = .04327) demonstrated a significant reduction in pain, whereas BC Sealer did not show differences in pain intensity, even in the maximum period evaluated of 1 week (P > .05). CONCLUSIONS: The occurrence of unintentional apical extrusion of calcium silicate-based root canal sealers presents similar postoperative pain results compared with resin-based sealers with low-intensity pain.

Induced Autophagy of Macrophages and the Regulation of Inflammatory Effects by Perovskite Nanomaterial LaNiO3.

Perovskite nanomaterials (NMs) possess excellent physicochemical properties and have promising applications in light-emitting diodes (LEDs), lasers, photodetectors, and artificial synapse electronics. Potential exposure to these NMs happens in the manufacture and application of the perovskite-based products, however, the biological safety of these NMs is still unknown. Here, we used the LaNiO3 NM (LNO), a typical kind of perovskite nanostructures to study the interaction with macrophages (J774A.1) and to explore its biological effects at the cellular level. Firstly, we characterized the properties of LNO including the size, shape, and crystal structure using Transmission electronic microscope (TEM), Dynamic lighting scattering (DLS), and X-ray diffraction (XRD). Secondly, to gain a better understanding of the biological effect, we evaluated the effect of LNO on cell viability and found that LNO induced cell autophagy at a concentration of 5 µg/ml and influenced the inflammatory response based on RT-PCR result. Finally, we demonstrated the mechanism that LNO causes cell autophagy and immune response is probably due to the metal ions released from LNO in acidic lysosomes, which triggered ROS and increased lysosomal membrane permeation. This study indicates the safety aspect of perovskite NMs and may guide the rational design of perovskite NMs with more biocompatibility during their manufacture and application.

Tooth Discoloration Induced by Different Calcium Silicate-Based Cements: A Two-Year Spectrophotometric and Photographic Evaluation in Vitro.

OBJECTIVE: Calcium silicate-based cements (CSCs) may lead to coronal staining in young permanent teeth over the time. The purpose of this study was to evaluate and compare the long-term tooth discoloration induced by different CSCs. STUDY DESIGN: Ninety freshly-extracted human molars were assigned randomly into 6 groups (n=15/group) according to the CSC used as a pulpotomy material: ProRoot MTA, MTA Angelus, NeoMTA, EndoSequence Putty, Biodentine and Negative control (No cement). The color was assessed at baseline, and thereafter at 3, 6, 12 and 24 months by using both a spectrophotometer and digital images taken with and without a cross-polarizing filter. The time-dependent changes in color (ΔE) were compared within and among groups using Analysis of Variance. RESULTS: Angelus MTA and ProRooT MTA showed severe coronal discoloration (p>0.05) starting at 3 months. ΔE values of NeoMTA, EndoSequence Bioceramic Putty and Biodentine were below the perceptibility threshold, with Biodentine showing greater ΔE values than NeoMTA and EndoSequence Putty in the absence of statistical significance (p>0.05). CONCLUSIONS: Discoloration elicited by CSCs may develop soon after placement, and continue to increase for up to two years. Angelus MTA and ProRooT MTA cannot be recommended for vital pulp therapies in the esthetic zone of young individuals.

Tooth discoloration induced by the different phases of a calcium aluminate cement: One-year assessment.

OBJECTIVES: To assess the discoloration of teeth treated with the different phases of calcium aluminate cement (CAC), in comparison with the conventional CAC and mineral trioxide aggregate (MTA). MATERIALS AND METHODS: Fifty bovine incisors were prepared and filled. Two millimeters of the filling was removed to fabricate a cervical plug with the following cements (n=10): CA(CaO.Al2 O3 ); CA2 (CaO.2Al2 O3 ); C12 A7 (12CaO.7Al2 O3 ); CAC and MTA. The initial color measurement was performed and after 7, 15, 30, 45, 90, 180, and 365 days new color measurements were performed to determine the color (ΔE00 ), lightness (ΔL'), chroma (ΔC'), hue differences (ΔH'), and the whiteness index (WID ). RESULTS: ΔE00 was significant for groups (p = 0.036) and periods (p < 0.05). The greater ΔE00 was observed after 365 days for CAC (12.8). C12 A7 (7.2) had the smallest ΔE00 . ΔL' and ΔC' were significant for groups and periods (p < 0.05). ΔH' was significant for periods (p < 0.05). After 365 days, significant reduction in lightness was observed for all groups. For CA, CA2 , CAC, and MTA groups, the WID values decreased over time (p < 0.05). CONCLUSIONS: The tested cements changed the color behavior of the samples, resulting in greater teeth darkening over time. CLINICAL SIGNIFICANCE: There is no long-term study assessing the discoloration induced by the different phases of CAC.

Tooth discoloration and the effects of internal bleaching on the novel endodontic filling material SavDen® MTA.

BACKGROUND/PURPOSE: Mineral trioxide aggregate (MTA) was widely used in endodontic therapy as bioceramic material. Although MTA has high biocompatibility, it may lead to tooth discoloration. The aim of this study was to investigate the discoloration of two different bioceramic materials and the effects of internal bleaching. METHODS: Thirty single-canal mandibular premolars were extracted and randomly assigned to three groups (n = 10), white ProRoot® MTA, SavDen® MTA and a control group. Endodontic access opening, cleaning and shaping were performed, then the teeth were obturated using the two bioceramic materials. Tooth color was recorded at baseline, day 1, and 1, 2, 4, 6, 8, 12, 16, and 24 weeks after treatment. At the end of 24 weeks, sodium perborate was used to perform internal bleaching. Tooth color was recorded at 1, 2, and 6 weeks subsequently. Teeth were measured using a DeguDent® spectrophotometer, and data were transformed into Commission Internationale de l'Eclairage (CIE) L∗a∗b∗ system. RESULTS: Teeth treated with white ProRoot® MTA showed significant color change and decrease in L∗ value. Internal bleaching leaded to decrease of the ΔE∗ value for all three groups and increase in the L∗ value. There was no difference in tooth discoloration between SavDen® MTA and the control group after obturation and internal bleaching. CONCLUSION: In terms of visual perception, white ProRoot® MTA tends to cause black and blue discoloration. SavDen® MTA, formulated with calcium lactate gluconate, could be used to reduce tooth discoloration in endodontic treatment.

Evaluation of Stress Distributions in Mandibular Molar Teeth with Different Iatrogenic Root Perforations Repaired with Biodentine or Mineral Trioxide Aggregate: A Finite Element Analysis Study.

INTRODUCTION: In this study, finite element analysis was used to evaluate the stress distributions in simulated mandibular molar teeth with various iatrogenic root perforation types after reparation with Biodentine (Septodont, Saint-Maur-des-Fossés, France) or mineral trioxide aggregate (MTA). METHODS: An extracted human mandibular molar tooth was scanned using a micro-computed tomographic device, and a 3-dimensional solid model was created. Then, 3 different iatrogenic perforation types (furcation perforation [FP], strip perforation [SP], and post drill perforation [PDP]) and 2 different repair materials (MTA and Biodentine [BD]) were simulated on the model. In addition, a sound tooth (ST) model (control) and a model left unrepaired for each type of perforation were created; then, access cavities were restored using resin composite, except for the sound tooth model. Consequently, a total of 10 experimental models were designed. An oblique force of 300 N angled at 45° to the occlusal plane was simulated. Evaluations of von Mises stress were performed in the perforated regions. RESULTS: Maximum von Mises stress values were 7.76 MPa for ST/corresponding to the FP region, 8.48 MPa for ST/corresponding to the SP region, 14.20 MPa for ST/corresponding to the PDP region, 10.89 MPa for FP /MTA, 7.65 MPa for FP/BD, 14.67 MPa for FP/unrepaired, 15.92 MPa for SP/MTA, 15.82 MPa for SP/BD, 21.95 MPa for SP/unrepaired, 10.20 MPa for PDP/MTA, 9.17 MPa for PDP/BD, and 17.86 MPa for PDP/unrepaired. CONCLUSIONS: The results of this finite element analysis indicated that BD models showed lower maximum von Mises stress values than the MTA models, and SPs exposed higher stress concentrations in root perforation regions than FPs and PDPs. The use of MTA and BD may reduce the risk of potentially harmful stress in root perforation regions.

Occupational risk resulting from exposure to mineral wool when installing insulation in buildings.

Mineral wool is widely used for thermal and sound insulation. The subject of the study is to identify hazards for employees resulting from exposure to mineral wool, when it is used to insulate buildings, and to assess the risk arising from this exposure. When installing mineral wool insulation, respirable mineral fibers, dust, and volatile organic compounds may pose a hazard at workplaces. Based on the results of concentration measurements, it was assessed that the probability of adverse health effects related to the work of insulation installers, resulting from exposure to mineral wool fibers, is low, but for dust associated with exposure, an average health risk was estimated. An additional threat may be the sensitizing effect of substances used as binders and additives improving the utility properties of mineral wool, for example, phenol formaldehyde resins. The paper also contains some information on the labeling of mineral wool; this is very important because the label allows downstream users to recognize mineral wools, the composition and properties of which cause that they are not classified as carcinogens. Int J Occup Med Environ Health. 2020;33(6):757-69.

Spectrophotometric Analysis of Coronal Tooth Discoloration Induced by Tricalcium Silicate Cements in the Presence of Blood.

INTRODUCTION: New tricalcium silicate cements have been shown to induce less coronal discoloration. The purpose of this in vitro study was to evaluate the degree of color change induced by various silicate materials in the presence and absence of blood. METHODS: One hundred human extracted anterior single-canal teeth were sectioned to standardized root lengths, accessed, and instrumented. Eight random experimental groups and 2 control groups were created wherein specimens were filled with experimental materials below the buccal cementoenamel junction as follows: EndoSequence RRM putty (Brasseler USA, Savannah, GA), EndoSequence RRM fast set putty (Brasseler USA), Biodentine (Septodont, Saint-Maur-des-Fossés, France), and white mineral trioxide aggregate (Dentsply Sirona, York, PA) either with the presence or absence of blood. Blood-only and saline-only samples were used for the positive and negative controls. After incubation in 100% humidity at 37°C, color changes were evaluated with a spectrophotometer (Ocean Optics, Dunedin, FL) on days 0, 30, 60, and 180 after material placement. Data were transformed into Commission International de I'Eclairage's L∗a∗b color values, and corresponding ΔE values were calculated. The 1-way analysis of variance test was performed for statistical analysis. RESULTS: Discoloration was observed in all specimens in the presence of blood. There was no statistical significance when comparing different materials in contact with blood. Intragroup observation at various time points, Biodentine, and EndoSequence RRM fast set putty showed significant difference between the presence and absence of blood at 180 days (P < .05). CONCLUSIONS: Contamination with blood of tricalcium silicate materials has the potential to cause coronal tooth discoloration.

Investigating the health disparities in the association between lifestyle behaviors and the risk of head and neck cancer.

Many studies have reported a positive association between lower socioeconomic status (SES) and higher head and neck cancer (HNC) risk. Fewer studies have examined the impact of SES on the association between alcohol or cigarette use and HNC risk. The current case-control study (1104 HNC cases and 1363 controls) investigated the influence of education, a SES indicator, on the association between HNC and the use of alcohol, cigarettes, or betel quids in Taiwan, a country with universal health care. Our results showed a larger increase in HNC risk associated with alcohol among those with lower educational level (odds ratio [OR] = 2.07; 95% confidence interval [CI], 1.53-2.80) than those with higher educational level (OR = 1.38; 95% CI, 1.04-1.85) (heterogeneity-P = .03). Educational level had an influence on the association between alcohol use and HNC risk among those with genetic susceptibility (ALDH2-deficient) to the carcinogenic effect of alcohol. The association between cigarette or betel quid use and HNC risk was similar between the high and low educational groups. National policies and social interventions have led to the decline in the prevalence of cigarette and betel quid users in Taiwan. In contrast, due to the lack of adequate alcohol control policies, alcohol consumption in Taiwan has continued to rise. A higher impact of alcohol on HNC risk among lower SES individuals even with universal health care could be the result of insufficient alcohol control policies in Taiwan.

Pre-application of dentin bonding agent prevents discoloration caused by mineral trioxide aggregate.

BACKGROUND: To evaluate tooth discoloration by newly developed calcium silicate-based materials, and to examine the pre-application of dentin bonding agent (DBA) for preventing discoloration caused by mineral trioxide aggregate (MTA). METHODS: The roots of 50 premolars were randomly divided into five groups (n = 10) and cavities were prepared from resected root surfaces. MTA was placed in the cavities of teeth belonging to the ProRoot MTA (MTA) and RetroMTA (RMTA) groups. For teeth belonging to the ProRoot + DBA (MTA-B) and RetroMTA + DBA (RMTA-B) groups, DBA was first applied to the cavities prior to the addition of MTA. Teeth in the control group were restored with composite resin only (i.e., without MTA). After 12 weeks, MTA was removed from the MTA and RMTA groups and bleaching agents were applied for 3 additional weeks. Color assessments were recorded at baseline, and 1, 4, and 12 weeks, as well as after bleaching. A one-way ANOVA was performed to assess the differences between the two types of MTAs and color changes following DBA pre-application in each MTA group. A p-value of < 0.05 was considered indicative of statistical significance. RESULTS: Following 12 weeks of MTA treatment, there was a significant difference between the discoloration in the MTA and RMTA groups (p < 0.05). However, no significant difference was observed between the RMTA and RMTA-B groups (p > 0.05). Following bleaching, the color changes (ΔE values) of the MTA group were not significantly different from those of the MTA-B group (p > 0.05). The difference of ΔE between the RMTA group after internal bleaching and the RMTA-B group was also not significant (p > 0.05). CONCLUSIONS: RetroMTA caused significantly less discoloration than ProRoot MTA. Pre-application of DBA reduced discoloration caused by ProRoot MTA. MTA discoloration was improved equally well between DBA pre-application and post-bleaching.