Sclerostin is a promising therapeutic target for oral inflammation and regenerative dentistry.

Sclerostin is the protein product of the SOST gene and is known for its inhibitory effects on bone formation. The monoclonal antibody against sclerostin has been approved as a novel treatment method for osteoporosis. Oral health is one of the essential aspects of general human health. Hereditary bone dysplasia syndrome caused by sclerostin deficiency is often accompanied by some dental malformations, inspiring the therapeutic exploration of sclerostin in the oral and dental fields. Recent studies have found that sclerostin is expressed in several functional cell types in oral tissues, and the expression level of sclerostin is altered in pathological conditions. Sclerostin not only exerts similar negative outcomes on the formation of alveolar bone and bone-like tissues, including dentin and cementum, but also participates in the development of oral inflammatory diseases such as periodontitis, pulpitis, and peri-implantitis. This review aims to highlight related research progress of sclerostin in oral cavity, propose necessary further research in this field, and discuss its potential as a therapeutic target for dental indications and regenerative dentistry.

Proteoliposome-Incorporated Seawater Reverse Osmosis Polyamide Membrane: Is the Aquaporin Water Channel Effect in Improving Membrane Performance Overestimated?

The water channel feature of the aquaporin (AQP) is considered to be the key in improving the permselectivity of AQP-based thin-film composite (TFC) polyamide (PA) membranes, yet much less attention has been paid to the physicochemical property changes of the PA layer induced by AQP-reconstituted proteoliposomes. This study systematically investigated the roles of proteoliposome constituents (liposome/detergent/AQP) in affecting the physicochemical properties and performance of the membranes. For the first time, we demonstrated that the constituents in the proteoliposome could facilitate the formation of a PA layer with enlarged protuberances and thinner crumples, resulting in a 79% increase in effective surface area and lowering of hydraulic resistance for filtration. These PA structural changes of the AQP-based membrane were found to contribute over 70% to the water permeability increase via comparing the separation performance of the membranes prepared with liposome, detergent, and proteoliposome, respectively, and one proteoliposome-ruptured membrane. The contribution from the AQP water channel feature was about 27% of water permeability increase in the current study, attributed to only ∼20% vesicle coverage in the PA matrix, and this contribution may be easily lost as a result of vesicle rupture during the real seawater reverse osmosis process. This study reveals that the changed morphology dominates the performance improvement of the AQP-based PA membrane and well explains why the actual AQP-based PA membranes cannot acquire the theoretical water/salt selectivity of a biomimetic AQP membrane, deepening our understanding of the AQP-based membranes.

Early soft tissue response to zirconium oxide and titanium healing abutments in vivo: a study in dogs.

BACKGROUND: This study aimed to investigate the clinical characteristics and early soft tissue response to zirconium oxide (Zr) and titanium (Ti) healing abutments in dogs. METHODS: Eight implants (four at each hemi-mandible) were inserted after bilateral mandibular third and fourth premolars and first molar extraction in dogs. Then, two Zr and two Ti healing abutments were connected to each unilateral mandible eight weeks later. The ligation method was used to create a peri-implant mucositis model and the 24 abutments were divided into four groups: Zr or Ti healing abutments with ligation (ZrL, TiL) or non-ligation (ZrN, TiN). The clinical indices, peri-implant crevicular fluid (PICF), and inflammatory cytokines (TNF-α and IL-1ß) were measured and analyzed on days 0 and 28. The dogs were then sacrificed on day 28, soft tissues around the implants were harvested, and inflammation infiltration was tested by immunohistochemistry. Normal distribution test and two-way analysis of variance was used to analyze the data. RESULTS: The results showed that the clinical indices were similar for Zr and Ti healing abutments. There was significantly more PICF in the ZrL and TiL groups compared to in the ZrN and TiN groups. The TNF-α levels in PICF were significantly different between ZrL and ZrN groups on day 28. And the TNF-α levels in PICF were significantly higher in TiL group on day 28 than that on day 0. However, the number of inflammatory cells was not significantly different between the groups as measured by immunohistochemistry. CONCLUSIONS: These data indicate that soft tissue responses to Zr healing abutments with peri-implant mucositis were comparable to those of Ti healing abutments in vivo, providing a theoretical foundation for the clinical application of Zr abutments.

Sclerostin inhibits odontogenic differentiation of human pulp-derived odontoblast-like cells under mechanical stress.

Sclerotic dentin is a natural self-protective barrier beneath non-carious cervical lesions (NCCLs), which are mainly induced by mechanical stress. Sclerostin is a mechanosensory protein and serves as an inhibitor of dentinogenesis. However, its function on mechanotransduction in dentine-pulp complex has not been elucidated yet. In this study, decreased sclerostin expression was detected in odontoblasts beneath NCCL-affected sclerotic dentin. Then human pulp-derived odontoblast-like cells (hOBs) were subjected to mechanical strain (MS) in vitro: the results showed that MS-induced upregulation of odontogenic differentiation markers (dentin sialophosphoprotein, osteopontin, osteocalcin, and runt-related transcription factor 2) in hOBs with downregulated sclerostin expression, and this inductive differentiation was attenuated when sclerostin was overexpressed. Additionally, MS activated ERK1/2 pathway and ERK1/2 inhibition restored MS-induced downregulation of sclerostin. Proteasome inhibitor MG132 could also rescue MS-induced decrease of sclerostin. Furthermore, MS suppressed STAT3 pathway, which could be reversed by sclerostin overexpression. STAT3 inhibition was shown to ameliorate the reduction of odontogenic markers induced by sclerostin overexpression. Taken together, we conclude that MS downregulates sclerostin expression via the ERK1/2 and proteasome signaling pathways to promote odontogenic differentiation of hOBs through the STAT3 signaling pathway. It can therefore be inferred that under mechanical stress, sclerostin inhibition promotes reactive dentin formation by enhancing odontogenic differentiation of odontoblasts, which might be one of potential forming mechanisms of sclerotic dentin beneath NCCLs.

Protective roles of FICZ and aryl hydrocarbon receptor axis on alveolar bone loss and inflammation in experimental periodontitis.

AIM: The aryl hydrocarbon receptor (AhR)-ligand axis has been shown to be involved in inflammatory diseases and bone homeostasis. However, the activation of AhR signalling pathway and the possible functions of AhR ligands in periodontitis are underexplored. This study investigated the expression of the AhR target gene cytochrome P450 subfamily B member 1 (CYP1B1) and the functions and mechanisms of the AhR ligand 6 formylindolo[3,2-b]carbazole (FICZ) in periodontitis. MATERIALS AND METHODS: CYP1B1 expression was detected in human periodontitis samples, mice with ligature-induced periodontitis and lipopolysaccharide (LPS)-induced inflammation in periodontal ligament cells (PDLCs) in vitro. FICZ was administered topically or systemically. The therapeutic functions of FICZ were detected via qPCR, micro-computed tomography and immunohistochemistry. Finally, the mechanisms of AhR signalling in periodontitis were investigated by cell assays. RESULTS: CYP1B1 expression was downregulated in periodontitis. FICZ rescued the alveolar bone loss and mitigated the inflammatory cytokines in periodontitis mice. In vitro, FICZ pre-treatment reduced the LPS-induced inflammation in PDLCs via the increased phosphorylation of STAT3. Additionally, FICZ prompted the mineralization of PDLCs via activation of the Wnt/ß-catenin signalling pathway. CONCLUSION: AhR signalling pathway is suppressed in periodontitis and the AhR ligand FICZ can prevent periodontitis.

Modifications of Poly(Methyl Methacrylate) Cement for Application in Orthopedic Surgery.

Even with the emerging of newly-developed bone substitutes, poly(methyl methacrylate) (PMMA) cement is still a widely-used bone replacing biomaterial in orthopedic surgery with a long history. However, aseptic loosening, infection of the prosthesis and thermal necrosis to surrounding tissue are the common complications of PMMA. Therefore, additives have been incorporated in PMMA cement to target those problems. This chapter summarizes different additives to improve the performance of the PMMA cement, i.e.: (1) bioceramic additives; (2) filler additives; (3) antibacterial additives; (4) porogens; (5) biological agents, and (6) mixed additives. To improve the biological and mechanical performance of PMMA cement, mixed additives aiming to fabricate multifunctional PMMA seem the most suitable choice. Although in vivo animal studies have been conducted, long-term and clinical studies are still needed to evaluate the modifications of multifunctional PMMA cement for matching a specific clinical application.

Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols.

OBJECTIVE: The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials. MATERIALS AND METHODS: The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ0 ). RESULTS: Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ0 values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ0 , and color changes. CONCLUSIONS: Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent. CLINICAL SIGNIFICANCE: The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative materials.

Evaluation of a Novel Computer Color Matching System Based on the Improved Back-Propagation Neural Network Model.

PURPOSE: To explore the feasibility of a novel computer color-matching (CCM) system based on the improved back-propagation neural network (BPNN) model by comparing it with the traditional visual method. MATERIAL AND METHODS: Forty-three metal-ceramic specimens were fabricated by proportionally mixing porcelain powders. Thirty-nine specimens were randomly selected to train the BPNN model, while the remaining four specimens were used to test and calibrate the model. A CCM system based on the improved BPNN model was constructed using MATLAB software. A comparison of the novel CCM system and the traditional visual method was conducted by evaluating the color reproduction results of 10 maxillary central incisors. Metal-ceramic specimens were fabricated using two color reproduction approaches. Color distributions (L*, a*, and b*) of the target teeth and of the corresponding metal-ceramic specimens were measured using a spectroradiometer. Color differences (ΔE) and color distributions (ΔL*, Δa*, and Δb*) between the teeth and their corresponding specimens were calculated. RESULTS: The average ΔE value of the CCM system was 1.89 ± 0.75, which was lower than that of the visual approach (3.54 ± 1.11, p < 0.01). With respect to color distributions, substantial differences were found between the two color-matching systems, except for ΔL* (p > 0.05). CONCLUSION: The novel CCM system produced greater accuracy in color reproduction within the given color space than the traditional visual approach.

[Remineralization of demineralized dentin induced by bioactive glass NovaMin].

OBJECTIVE: To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface.
 Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface.
 Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open.
 Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.

Evaluation of the effectiveness of micro-Raman spectroscopy in monitoring the mineral contents change of human enamel in vitro.

The purpose of this in vitro study was to investigate the efficacy of micro-Raman spectroscopy on detecting mineral content change during the demineralization and de/remineralization cycling process. The enamel samples (n = 55) were randomly divided into three groups and separately treated with demineralization solution (n = 20), de/remineralization cycling solution (n = 30), and distilled water (n = 5). Micro-Raman spectroscopy, microhardness (MHS), and the released calcium ions concentration were performed before and after treatment, respectively. A one-way analysis of variance (ANOVA) with a post hoc Tukey test was used to analyze the results. The Spearman correlation coefficients among the parameters of Raman relative intensity decrease (RRID%), the percentage of MHS loss (PML), and the released calcium ions concentration were also analyzed. In demineralization group, RRID%, PML, and released calcium ions concentration were highly correlated with each other (r = 0.979, p < 0.001; r = 0.984, p < 0.001; and r = 0.983, p < 0.001, respectively). While for the de/remineralization cycling group, there also existed a high correlation between RRID% and PML (r = 0.987, p < 0.001). In conclusion, micro-Raman spectroscopy could effectively monitor the mineral content change, and its efficacy was validated by the measurement of released calcium ions concentration and MHS.

The effect of ceramic thickness and resin cement shades on the color matching of ceramic veneers in discolored teeth.

The objective of this study was to analyze the effects of ceramic material thickness and resin cement shade on the color matching of ceramic veneers at the gray tooth structures. Seventy-two artificial maxillary right central incisor teeth (C2 shade) were prepared according to veneer tooth preparation in practice. Ceramic materials (LT, A2 shade, IPS e.max Press) were selected to fabricate the 0.50- and 0.75-mm thick veneers at the body region. The ceramic veneer specimens were bonded to the artificial teeth by the 6 shades of resin cements (Variolink Veneer: shades of HV+3, LV-2, LV-3; and RelyXTM Veneer: shades of WO, TR, A3). A clinical spectrophotometer (Crystaleye, Olympus) was used to measure the color parameters. The color differences (ΔE values) of ceramic veneers and A2 shade tab (Vitapan Classical, Vita) and C* ab values were calculated. The results of three-way ANOVA indicated that the ΔE values of ceramic veneer and A2 shade tab were significantly different in the thickness of ceramic materials, shades of resin cements, and measuring regions (p < 0.001). There were significant differences in 0.50-mm-thick ceramic veneers that exhibited higher ΔE values compared with veneers that were 0.75-mm thick. Tukey's HSD test showed that the average ΔE values in body region were significantly smaller than that in cervical and incisal regions. The color matching of ceramic veneers was significantly influenced not only by the ceramic thickness and the resin cement shades but also the tooth regions.

Analyzing the Evolution of Membrane Fouling via a Novel Method Based on 3D Optical Coherence Tomography Imaging.

The development of novel tools for studying the fouling behavior during membrane processes is critical. This work explored optical coherence tomography (OCT) to quantitatively interpret the formation of a cake layer during a membrane process; the quantitative analysis was based on a novel image processing method that was able to precisely resolve the 3D structure of the cake layer on a micrometer scale. Fouling experiments were carried out with foulants having different physicochemical characteristics (silica nanoparticles and bentonite particles). The cake layers formed at a series of times were digitalized using the OCT-based characterization. The specific deposit (cake volume/membrane surface area) and surface coverage were evaluated as a function of time, which for the first time provided direct experimental evidence for the transition of various fouling mechanisms. Axial stripes were observed in the grayscale plots showing the deposit distribution in the scanned area; this interesting observation was in agreement with the instability analysis that correlated the polarized particle groups with the small disturbances in the boundary layer. This work confirms that the OCT-based characterization is able to provide deep insights into membrane fouling processes and offers a powerful tool for exploring membrane processes with enhanced performance.

Influence of bone marrow-derived mesenchymal stem cells pre-implantation differentiation approach on periodontal regeneration in vivo.

AIM: The implantation of bone marrow-derived mesenchymal stem cells (MSCs) has previously been shown successful to achieve periodontal regeneration. However, the preferred pre-implantation differentiation strategy (e.g. maintenance of stemness, osteogenic or chondrogenic induction) to obtain optimal periodontal regeneration is still unknown. This in vivo study explored which differentiation approach is most suitable for periodontal regeneration. MATERIALS AND METHODS: Mesenchymal stem cells were obtained from Fischer rats and seeded onto poly(lactic-co-glycolic acid)/poly(ɛ-caprolactone) electrospun scaffolds, and then pre-cultured under different in vitro conditions: (i) retention of multilineage differentiation potential; (ii) osteogenic differentiation approach; and (iii) chondrogenic differentiation approach. Subsequently, the cell-scaffold constructs were implanted into experimental periodontal defects of Fischer rats, with empty scaffolds as controls. After 6 weeks of implantation, histomorphometrical analyses were applied to evaluate the regenerated periodontal tissues. RESULTS: The chondrogenic differentiation approach showed regeneration of alveolar bone and ligament tissues. The retention of multilineage differentiation potential supported only ligament regeneration, while the osteogenic differentiation approach boosted alveolar bone regeneration. CONCLUSION: Chondrogenic differentiation of MSCs before implantation is a useful strategy for regeneration of alveolar bone and periodontal ligament, in the currently used rat model.

The dentin tubule occlusion effects of desensitizing agents and the stability against acids and brushing challenges.

PURPOSE: To investigate the effects of desensitizing agents on dentin tubule occlusion, acid and tooth brushing challenge, and microhardness change of human dentin. METHODS: Partially demineralized dentin slabs were divided into four groups (n = 30): (1) Control, (2) Non-desensitizing toothpaste, (3) Pro-Argin toothpaste, (4) CPP-ACP paste. The specimens were treated with these dentifrices for 2 minutes/day and soaked in artificial saliva (AS) for 24-hour remineralization. Then the dentin discs were divided into three subgroups for removal resistance tests: acid challenge, mechanical brushing challenge and blank control. Changes in dentin morphology were observed using scanning electron microscopy (SEM). Vickers microhardness measurements were performed at baseline and after 24-hour remineralization for all groups. RESULTS: A surface layer and intra-tubular crystals were observed in SEM imaging of Pro-Argin toothpaste and CPP-ACP paste groups, which occluded most of the dentin tubules for those specimens. But the dentin tubules were opened after the acid challenge again. Moreover, the dentin microhardness showed a slight increase after 24-hour AS immersion. The percentage microhardness gain (PMG) values of these two groups were 5.4% and 5.1% respectively, which were significantly higher than the other groups (P < 0.05).

Effect of in-office bleaching agents on the color changes of stained ceromers and direct composite resins.

PURPOSE: To evaluate the effect of two in-office bleaching agents on the color changes of two ceromers (Ceramage and Adoro SR) and one direct composite resin (Gradia Direct Anterior) after staining by tea and coffee. MATERIALS AND METHODS: Twenty-four disk-shaped specimens were fabricated for each resin material and randomly divided into three groups (n = 8). The specimens were immersed in tea, coffee or deionized water, respectively, for 7 days. Each group was then equally divided into two sub-groups (n = 4), which were subjected to two in-office bleaching agents (BEYOND and Opalescence Boost), respectively. The color of the specimens was measured by a spectrophotometer at baseline, after staining and after bleaching. The color differences (ΔE values) between baseline and after treatments were calculated. RESULTS: Statistical analysis indicated that the staining solution had significant influence on the color change of resin composites tested (p < 0.001). The discolorations of resin composites were perceptible after immersing in tea or coffee solutions (ΔE>2.0). There was no statistically significant difference between BEYOND and Opalescence Boost in stains removal from discolored resins (p = 0.550). The color changes in ΔE value between baseline and after bleaching were less than 2.0 for all resin composite groups. CONCLUSIONS: Tea solution produces severe discoloration of three resin composites tested. The two in-office bleaching agents can effectively remove the stains from two ceromers and one direct composite resin tested in this study.

Evaluation of an optimized shade guide made from porcelain powder mixtures.

STATEMENT OF PROBLEM: Color errors associated with current shade guides and problems with color selection and duplication are still challenging for restorative dentists. PURPOSE: The purpose of this study was to evaluate an optimized shade guide for visual shade duplication. MATERIAL AND METHODS: Color distributions (L*, a*, and b*) of the maxillary left central incisors of 236 participants, whose ages ranged from 20 to 60, were measured with a spectrophotometer. Based on this color map, an optimized shade guide was designed with 14 shade tabs evenly distributed within the given color range of the natural incisors. The shade tabs were fabricated with porcelain powder mixtures and conventional laboratory procedures. A comparison of shade duplication by using the optimized and Vitapan Classical shade guides was conducted. Thirty Chinese participants were involved, and the colors of the left maxillary incisors were selected by using 2 shade guides. Metal ceramic crowns were fabricated according to the results of the shade selection. The colors of the shade tabs, natural teeth, and the ceramic crowns were measured with a spectrophotometer. The color differences among the natural teeth, the shade tabs, and the corresponding metal ceramic crowns were calculated and analyzed (α=.017). RESULTS: Significant differences were found in both phases of shade determination and shade duplication (P<.017). The total number of color errors with the optimized shade guide was 3.5, which was significantly less than that of Vitapan, 5.1 (P<.001). CONCLUSIONS: The optimized shade guide system improved performance not only in the color selection phase but also in the color of the fabricated crowns.

Agreement of try-in pastes and the corresponding luting composites on the final color of ceramic veneers.

PURPOSE: The aims of this study were to evaluate the influence of luting composites on the final color of ceramic veneers and to investigate the color matching of try-in pastes to the corresponding luting composites. MATERIALS AND METHODS: Ceramic discs (shade A3, 1.0 mm thick) were fabricated and seated on composite specimens (shade A3) to mimic a complex of ceramic veneer lying on dentin substrate. The try-in pastes and luting composites of 3M RelyX were applied into the interlayer of the ceramic and composite specimens. The colors of the complexes were measured using a spectrophotometer, and subsequently converted to CIE L*a*b* values. Color changes after luting composites were applied, and the changes between the try-in pastes and the corresponding luting composites were calculated and registered as ΔEluting and ΔEpaste-luting . Color measurements were repeated while the ceramic specimens were reduced to 0.7 mm and then 0.5 mm in thickness. RESULTS: The means of ΔEluting were 0.69 ± 0.21, 1.27 ± 0.48, and 1.40 ± 0.57 for the 1.0, 0.7, and 0.5 mm thicknesses, respectively. Two-way ANOVA revealed that ΔEpaste-luting values were significantly affected by the colors of luting composites and veneer thickness (p < 0.001). Lighter shades of luting composites showed less influence on ΔEpaste-luting values. CONCLUSIONS: Luting composites could slightly modify the final color of ceramic veneers. Color matching of a try-in paste to the corresponding luting composite was not always achieved in the 0.7 or 0.5 mm thicknesses.

In vitro evaluation of halogen light-activated vs chemically activated in-office bleaching systems.

OBJECTIVES: To compare the tooth whitening efficacy, temperature and HP concentration changes induced by halogen light-activated and chemically activated in-office bleaching systems. MATERIALS AND METHODS: Twenty-four extracted premolars were randomly divided into two groups (n = 12): Group BL (35% HP with halogen light activation) and Group OP (38% HP with chemical activation). Tooth color was measured by a spectrophotometer according to the CIE L*a*b* color space system. Temperatures of bleaching gels and pulp chambers during the bleaching process were monitored and recorded by a digital multimeter with K-type thermocouple. HP concentrations were tested before and after treatments by iodometry. ANOVA and paired t-test were used for statistical analyses at the significance of p < 0.05. RESULTS: Tooth whitening resulted in the increase of ΔL* and ΔE and reduction of Δb*. Paired t-tests revealed groups BL had greater ΔE than group OP, however, there was no statistically significant difference in ΔE between them after 3 weeks post-treatment. Maximal temperature rise (ΔT) was found only in group BL, showing the increment of 2.55 and 2.02°C for bleaching gels and pulp chambers, respectively. HP concentrations were higher than baseline values for group OP (p < 0.001) rather than group BL. CONCLUSIONS: Halogen light and chemically activated in-office bleaching systems were both effective for tooth whitening, but halogen light activation could improve the immediate whitening effect. In contrast, chemical activation was a more conservative method due to the little temperature rise in pulp chambers.

Application of vertical transposition flap in closure for large facial soft tissue defects in children.

Background: While transposition flap is widely used for the repairs of facial defects, few studies has reported its application among children with large defects. In this study, we aimed to investigate the surgical techniques and principles in different locations on face of vertical transposition flap in children. Methods: We retrospectively reviewed our hospital database and identified children who were treated with vertical transposition flap for large facial defects between January 2014 and December 2021. Information was collected including patients' demographics, location and dimension of the lesion, surgical procedure, additional surgeries, complications, and outcomes. Results: A total of 122 patients (77 boys, 63.1%) were included in this study. The average age for participants was 3.3 years (3 months to 9 years). One hundred and four (85.3%) patients had melanin nevus and 18 (14.8%) had sebaceous nevus. The average size of defects was 5.8 cm2 (ranging from 0.8-16.5 cm2). Ten patients (8.2%) suffered from dermal layer or full-thickness necrosis in the distal part of their flaps, They all recovered after conservative treatment and there were noticeable scars at discharge. Five patients (4.1%) had slight traction of the mouth and eyelid, all recovered about 2 week after surgery. An acceptable cosmetic outcome was achieved for all the patients at last time follow-up. Conclusions: Repairing large facial defects with vertical transposition flap is effective in Children, especially on forehead, cheek and mandible. However, this technique is far from perfect. Careful selection of appropriate patients and flap design might be needed.

Microscopic characterization of FO/PRO membranes--a comparative study of CLSM, TEM and SEM.

Osmotically driven membrane processes (including forward osmosis (FO) and pressure retarded osmosis (PRO)) have received increasing attention in recent decades. The performance of an FO/PRO membrane is significantly limited by internal concentration polarization, which is a strong function of the membrane support layer pore structure. The objective of the current study was to develop microscopic characterization methods for quantitative/semiquantitative analysis of membrane pore structure (both pore diameter and porosity distribution across membrane thickness). The use of confocal laser scanning microscopy (CLSM) for noninvasive characterization of the internal pore structure of FO/PRO membranes is reported for the first time. By performing optical sectioning, information on pore diameter, porosity depth profile and pore connectivity can be obtained. The CLSM porosity results are further compared to those obtained using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and reasonably good agreement was observed. A comparison of these characterization methods reveals their complementary nature, and a combination of these techniques may allow a more comprehensive understanding of membrane structure. The current study also provided a comprehensive insight into the pore structure of commercially available FO/PRO membranes.