OBJECTIVES: The metabolomics technique of LC-MS/MS combined with data analysis was used to detect changes and differences in metabolic profiles in the vitreous humor of early rat carcasses found in water, and to explore the feasibility of its use for early postmortem submersion interval (PMSI) estimation and the cause of death determination. METHODS: The experimental model was established in natural lake water with 100 SD rats were randomly divided into a drowning group (n=50) and a postmortem (CO₂ suffocation) immediately submersion group (n=50). Vitreous humor was extracted from 10 rats in each group at 0, 6, 12, 18 and 24 h postmortem for metabolomics analyses, of which 8 were used as the training set to build the model, and 2 were used as test set. PCA and PLS multivariate statistical analysis were performed to explore the differences in metabolic profiles among PMSI and causes of death in the training set samples. Then random forest (RF) algorithm was used to screen several biomarkers to establish a model. RESULTS: PCA and PLS analysis showed that the metabolic profiles had time regularity, but no differences were found among different causes of death. Thirteen small molecule biomarkers with good temporal correlation were selected by RF algorithm. A simple PMSI estimation model was constructed based on this indicator set, and the data of the test samples showed the mean absolute error (MAE) of the model was 0.847 h. CONCLUSIONS The 13 metabolic markers screened in the vitreous humor of rat corpses in water had good correlations with the early PMSI. The simplified PMSI estimation model constructed by RF can be used to estimate the PMSI. Additionally, the metabolic profiles of vitreous humor cannot be used for early identification of cause of death in water carcasses.
Animals ; Biomarkers/metabolism* ; Cadaver ; Chromatography, Liquid ; Immersion ; Postmortem Changes ; Rats ; Rats, Sprague-Dawley ; Tandem Mass Spectrometry ; Vitreous Body/metabolism* ; Water/metabolism*

PURPOSE: This study evaluated color stability of Dentca 3D-printed denture teeth, in comparison to color stabilities of four conventional types of denture teeth, upon being immersed in various colorants.MATERIALS AND METHODS: Four types of conventional prefabricated denture teeth (Surpass, GC, Artic 6, Heraeus Kulzer, Premium 6, Heraeus Kulzer, Preference, Candulor), 3D-printed denture teeth (Dentca); and Z250 (Filtek Z250, 3M ESPE) were prepared for testing. The samples were immersed in erythrosine 3%, coffee, cola, and distilled water (DW) at 37℃. Color change (ΔE) was measured by spectrophotometer before immersion and at 7, 14, and 21 days after immersion. One-way analysis of variance was performed along with Tukey's honestly significant difference multiple comparisons test (P<.05).RESULTS: No great difference was observed between the color change of Dentca denture teeth and that of conventional denture teeth in most cases (P>.05). The color change of Dentca denture teeth immersed in erythrosine 3% was greater than that of Surpass (ΔE = 0.67 ± 0.25) after 1 week; Artic 6 (ΔE = 1.44 ± 0.38) and Premium 6 (ΔE = 1.69 ± 0.35) after 2 weeks; and Surpass (ΔE = 1.79 ± 0.49), Artic 6 (ΔE = 2.07 ± 0.21), Premium 6 (ΔE = 2.03 ± 0.75), and Preference (ΔE = 2.01 ± 0.75) after 3 weeks (P<.05).CONCLUSION: A color change was observed in Dentca denture teeth when immersed in some colorants; however, the maximum value of ΔE for Dentca denture teeth was within the clinically acceptable range.
Coffee ; Cola ; Dentures ; Erythrosine ; Immersion ; Printing, Three-Dimensional ; Tooth ; Water

Postmortem interval （PMI） estimation is one of the most important and difficult academic tasks in forensic sciences. Due to the influence of the corpse itself and the water environment, corpses in water have unique corruption phenomenon and laws. Based on the experience of traditional PMI studies of corpses on land, forensic practitioners across the world have proposed a variety of practical methods for estimating postmortem submersion interval （PMSI）. This paper summarizes the literatures related to PMSI in recent years, and introduces methods to infer PMSI according to the phenomenon of corpses, the development of insects, the succession pattern of aquatic organisms, and the changes of other physical and chemical indexes of corpses, in order to provide some reference for the study of PMSI of corpses in water.
Animals ; Autopsy ; Cadaver ; Forensic Medicine ; Immersion ; Postmortem Changes

PURPOSE: The aim of this study was to evaluate the influence of polishing methods on the color stability of composite resins. MATERIALS AND METHODS: Two bulk-fill and four conventional resin composites were filled in cylindrical molds (6 mm diameter, 4 mm height) and light-cured. The specimens were stored in 34℃ distilled water for 24 h. Spectrophotometer was used to determine the color value according to the CIE L(*)a(*)b(*) color space. Each group was divided into three groups according to polishing methods (n = 5). Group 1 was control group (Mylar strip group), group 2 was polished with PoGo, and group 3 was polished with Sof-Lex Spiral wheels. Color evaluation was performed weekly for 4 weeks after immersion in 34℃ distilled water. The results were analyzed by generalized least squares method (P < 0.05). RESULTS: Generalized least squares analysis revealed that Sof-Lex Spiral wheels group showed the significantly lower ΔE values compared to PoGo and control group (P < 0.05). The ΔE values of polished group showed the significantly lower than the ΔE values of unpolished group (P < 0.05). Regarding color changes of composite resins, there was no significant difference between the ΔE values of Filtek Z250 and Filtek Z350 XT Universal restorative in all time intervals (P < 0.05). Tetric N-Ceram Bulk Fill showed the significantly lower ΔE values compared to other composite resins in 1, 2, 3 weeks (P < 0.05). CONCLUSION: Within the limitations of this study, polishing methods influence the color stabilities of composite resins. The group polished with Sof-Lex Spiral Wheels showed more resistance to discoloration than group polished with PoGo.
Absorption ; Composite Resins ; Fungi ; Immersion ; Least-Squares Analysis ; Methods ; Water

The use of the mineral trioxide aggregate (MTA) has been expanded as the material can be applied on various treatment of endodontic care, which also has many advantages including bioactivity. Still, the discolorations of the materials have been presented as a concern related to esthetic appearances, which is caused by the presence of radiopacifiers. Therefore, the aim of this study was to investigate the color stability and radiopacity of white MTA with various radiopacifiers. Four different radiopacifiers [bismuth oxide (BM), calcium tungstate (CT), barium oxide (BO), and zirconium oxide (ZO)] were used. The radiopacity was tested according to ISO 6876, and the color change before and after immersing in a 5% hypochlorite solution was tested using a spectrophotometer. The group with no radiopacifier (NR) was used as a negative control and ProRoot MTA (PR) was used as the commercial control. The immersion of the PR and BM in sodium hypochlorite resulted in a dark brown discoloration, in which the values were higher than the rest of the group (p<0.05). No change was observed in the NR. Moreover, the CT and ZO showed no color change compared to the NR (p>0.05). In terms of the radiopacity, the NR showed the lowest value as expected (p<0.05). Meanwhile, the BM showed the highest value (p<0.05), followed by PR and BO (p<0.05). The NR showed the lowest radiopacity values. The result of this study will be useful for future development of MTA that would have clinically adequate radiopacity with minimum discoloration.
Barium ; Calcium ; Hypochlorous Acid ; Immersion ; Miners ; Pemetrexed ; Sodium Hypochlorite ; Zirconium

The aim of this study was to examine the bioactivity and osseointegration of Ti-6Al-4V alloy implant which was modified by an anodic oxidation and a cyclic precalcification treatments. After blasting treatment using HAp (Hydroxyapatitie; HAp) powder which is resorbable blasting media (RBM) on the surface of Ti-6Al-4V alloy implants, the anodic oxidation treatment and the cyclic precalcification treatment were conducted to form nanotube TiO2 layer and HAp precipitation respectively. The surface morphology of the surface-treated Ti-6Al-4V alloy implant was investigated after immersion in the simulated body fluid(SBF) for 3 days to investigate the bioactivity. To investigate the effect of surface treatment on bonding between the implant and bone, RBM treated implant and RBM-anodization-cyclic precalcification(RACP) treated implant were placed on the distal side of both tibia diaphysis of rats, and then the removal torque of the implant was measured after 4 weeks. On the surface of RACP treated group, bone-like apatite precipitation was observed after immersion in SBF for 3 days. The removal torque was significantly higher in the RACP treated group than in the RBM treated group. The interfacial fracture between the implant and the new bone was observed in the RBM treated group, but both the cohesive fracture at the new bone and the interfacial fractures between the implant and the new bone were observed in the RACP treated group.
Alloys ; Animals ; Diaphyses ; Immersion ; Nanotubes ; Osseointegration ; Rats ; Tibia ; Torque

The calcium phosphate coating on various pretreated metals was prepared by soaking in modified simulated body fluid (m-SBF) solution. The coating structure and its surface morphologies were determined by x-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results revealed significant differences in morphology and composition of the calcium phosphate coatings with and without chitosan and NaOH-pretreated commercially pure titanium (cp-Ti) substrate. The calcium phosphates formed on chitosan coated-Ti pretreated with NaOH were ~ 350 nm-sized resulting in strong bonding of the apatite layer with the substrates and a uniform gradient of stress transfer from coating materials to the Ti-substrate. After NaOH pretreatment, the hydroxyl groups bind to Ca²⁺ to attract PO₄³⁻ anions, eventually resulting in a continuous layer of calcium phosphate on chitosan coated-Ti substrate during immersion in m-SBF solution. The chitosan coated-Ti showed hydrophobic surface while NaOH pretreatment resulted in maximum hydrophilicity to the Ti substrate. Due to improved wettability of Ti by NaOH pretreatment before chitosan coating, aggregation of calcium phosphate was prevented and size-controlled composite materials were obtained.
Anions ; Body Fluids ; Calcium Phosphates ; Calcium ; Chitosan ; Clothing ; Hydrophobic and Hydrophilic Interactions ; Immersion ; Metals ; Microscopy, Electron, Scanning ; Spectroscopy, Fourier Transform Infrared ; Titanium ; Wettability ; X-Ray Diffraction

Objective of this study was to compare the color stability, mechanical and chemical properties of three different types of temporary crown resins. Commercially available powder-liquid (Group PL), light-cured (Group LC) and auto-mix syringe (Group AM) types' temporary crown resins were used as experimental groups for each of the evaluation. All the test groups were evaluated after 1 day and 7 days of immersion in various staining solutions. The colors of all groups before and after storage in the staining solutions were measured by a spectrophotometer based on CIE Lab system, and the color differences (ΔE(*)) thereby calculated. Micro hardness test was performed before water storage and aging after 7 days at 37 ℃. In addition, flexural strength, water sorption and solubility tests were performed according to international standard, ISO 10477. All experimental groups showed significant color change in staining solutions when compared to those stored in the control solution (distilled water) (p<0.05). Group PL showed the least color change among the three groups followed by Group AM (p<0.05). This tendency was observed after 7 days of immersion. In terms of the micro hardness test, Group PL showed the highest value among the three groups followed by Group AM (p<0.05). Additionally, the flexural strength decreased in the following order: AM > PL > LC (p<0.05). Water sorption and solubility increased in the following order: AM < PL < LC (p<0.05). The results of this study would provide useful information when choosing temporary crown resin types in various clinical situations.
Aging ; Crowns ; Hardness Tests ; Immersion ; Solubility ; Syringes ; Water

The purpose of this study was to evaluate the color stability of light cured composite resins according to the resin matrices. Three kinds of resin matrices such as Bis-GMA (Venus® Diamond; VD), Silorane (FiltekTM P90; P90), and Ormocer (Admira; Ad) were selected. Each of them were used to prepare 30 specimens. The initial CIE L*a*b* values were measured by means of a Spectrophotometer (NF999, Nippon Denshoku, Japan). For accelerated aging process, the specimens were immersed in a circulating water bath with distilled water at 60℃. Spectrophotometric analyses were made after immersion of 8, 16, 24, 41 days and the color difference (ΔE*) was calculated. The L* value increased compared with initial L* value. VD had the greatest L* value change and Ad had the smallest L* value change (p<0.05). Ad had the greatest a* value change and VD had the smallest a* value change (p<0.05). The b* value of P90 increased steadily in positive value (+)(p<0.05). ΔE* of Ad had the smallest value and that of P90 had the greatest change with time. According to this study, the value of light cured composite resins was increased with water sorption and color of those changed into greenish and yellowish. And according to the evaluation of color stability, Ad with Ormocer as resin matrices had the best color stability with time in oral environment and P90 with Silorane as resin matrices had the lowest color stability with time. And VD had the greatest initial ΔE*.
Aging ; Baths ; Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Diamond ; Immersion ; Organically Modified Ceramics ; Silorane Resins ; Water

The pH of the oral cavity can dynamically change due to diverse foods and beverages served. The purpose of the present study was to evaluate flexural and compressive properties of composite resins after immersion in solutions of different pHs. Four composite resins were cured and immersed in test solutions of different pHs (3, 7.1, and 9) for 2 weeks. Flexural and compressive properties (strength and modulus) were evaluated using universal test machine. After immersion, initial flexural and compressive strength significantly changed to 1.5–30.0% and 0.3–19.6%, respectively; flexural and compressive modulus significantly changed to 4.4–29.0% and 3.5–21.5%, respectively. However, the values obtained from solutions of different pHs were not significantly and consistently different to each other.
Beverages ; Composite Resins ; Compressive Strength ; Hydrogen-Ion Concentration ; Immersion ; Mouth