Altered Foreign Body Response at the Posterior Surface Compared to the Anterior Surface of Human Silicone Breast Implants.

Soft implantable devices are crucial to optimizing form and function for many patients. However, periprosthetic capsule fibrosis is one of the major challenges limiting the use of implants. Currently, little is understood about how spatial and temporal factors influence capsule physiology and how the local capsule environment affects the implant structure. In this work, we analyzed breast implant capsule specimens with staining, immunohistochemistry, and real-time polymerase chain reaction to investigate spatiotemporal differences in inflammation and fibrosis. We demonstrated that in comparison to the anterior capsule against the convex surface of breast implants, the posterior capsule against the flat surface of the breast implant displays several features of a dysregulated foreign body reaction including increased capsule thickness, abnormal extracellular remodeling, and infiltration of macrophages. Furthermore, the expression of pro-inflammatory cytokines increased in the posterior capsule across the lifespan of the device, but not in the anterior capsule. We also analyzed the surface oxidation of breast explant samples with XPS analysis. No significant differences in surface oxidation were identified either spatially or temporally. Collectively, our results support spatiotemporal heterogeneity in inflammation and fibrosis within the breast implant capsule. These findings presented here provide a more detailed picture of the complexity of the foreign body reaction surrounding implants destined for human use and could lead to key research avenues and clinical applications to treat periprosthetic fibrosis and improve device longevity.

Chemical uptake into silicone wristbands over a five day period.

Silicone wristbands are a noninvasive personal exposure assessment tool. However, despite their utility, questions remain about the rate at which chemicals accumulate on wristbands when worn, as validation studies utilizing wristbands worn by human participants are limited. This study evaluated the chemical uptake rates of 113 organic pollutants from several chemical classes (i.e., polychlorinated biphenyls (PCB), organophosphate esters (OPEs), alkyl OPEs, polybrominated diphenyl ethers (PBDEs), brominated flame retardants (BFR), phthalates, pesticides, and polycyclic aromatic hydrocarbons (PAHs) over a five-day period. Adult participants (n = 10) were asked to wear five silicone wristbands and then remove one wristband each day. Several compounds were detected in all participants' wristbands after only one day. The number of chemicals detected frequently (i.e. in at least seven participants wristbands) increased from 20% of target compounds to 26% after three days and more substantially increased to 34% of target compounds after four days of wear. Chemicals detected in at least seven participants' day five wristbands (n = 24 chemicals) underwent further statistical analysis, including estimating the chemical uptake rates over time. Some chemicals, including pesticides and phthalates, had postive and significant correlations between concentrations on wristbands worn five days and concentrations of wristbands worn fewer days suggesting chronic exposure. For 23 of the 24 compounds evaluated there was a statistically significant and positive linear association between the length of time wristbands were worn and chemical concentrations in wristbands. Despite the differences that exist between laboratory studies using polydimethylsiloxane (PDMS) environmental samplers and worn wristbands, these results indicate that worn wristbands are primarily acting as first-order kinetic samplers. These results suggest that studies using different deployment lengths should be comparable when results are normalized to the length of the deployment period. In addition, a shorter deployment period could be utilized for compounds that were commonly detected in as little as one day.

Personal environmental exposure to plasticizers and organophosphate flame retardants using silicone wristbands and urine: Patterns, comparisons, and correlations.

Plasticizers (PLs) and organophosphate flame retardants (OPFRs) are ubiquitous in the environment due to their widespread use and potential for leaching from consumer products. Environmental exposure is a critical aspect of the human exposome, revealing complex interactions between environmental contaminants and potential health effects. Silicone wristbands (SWBs) have emerged as a novel and non-invasive sampling device for assessing personal external exposure. In this study, SWBs were used as a proxy to estimate personal dermal adsorption (EDdermal) to PLs and OPFRs in Belgian participants for one week; four morning urine samples were also collected and analyzed for estimated daily intake (EDI). The results of the SWBs samples showed that all the participants were exposed to these chemicals, and the exposure was found to be highest for the legacy and alternative plasticizers (LP and AP), followed by the legacy and emerging OPFRs (LOPFR and EOPFR). In urine samples, the highest levels were observed for metabolites of diethyl phthalate (DEP), di-isobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP) among LPs and di(2-ethylhexyl) terephthalate (DEHT) for APs. Outliers among the participants indicated that there were other sources of exposure that were not identified. Results showed a significant correlation between EDdermal and EDI for DiBP, tris (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPhP). These correlations indicated their suitability for predicting exposure via SWB monitoring for total chemical exposure. The results of this pilot study advance our understanding of SWB sampling and its relevance for predicting aggregate environmental chemical exposures, while highlighting the potential of SWBs as low-cost, non-invasive personal samplers for future research. This innovative approach has the potential to advance the assessment of environmental exposures and their impact on public health.

[Key Points of Examination after Breast Augmentation and Our Clinic's Algorithm of Immediate Reconstruction Using Silicone Implant for Breast Cancer Patient after Breast Augmentation].

Recently, the cases of breast augmentation for cosmetic purposes are rapidly increasing, there are more opportunities to examine for patient with breast augmentation history than before. In some cases, breast cancer screening is difficult due to the effects of breast augmentation. At our clinic, even in cases diagnosed with breast cancer after breast augmentation, we actively perform immediate breast reconstruction using silicone implant. However, it is necessary to consider the condition and type of breast augmentation at the time of diagnosis and also treatment. We will share our algorithm for immediate breast reconstruction using silicone implant for breast cancer after augmentation mammaplasty.

The Influence of Contamination and Different Cleaning Methods and the Effect of Plasma Treatment of CoCr Alloy on Tensile Bond Strength to Composite Resin.

PURPOSE: To investigate the influence of contamination and different cleaning methods on resin bonding to cobalt-chro- mium (CoCr) alloy disks. MATERIALS AND METHODS: A total of 160 CoCr disks were divided into 3 groups. The first group (N = 64) was air abraded with alumina particles and contaminated with a silicone disclosing agent and saliva; the second group (N = 64) was air abraded but not contaminated; the third group (N = 32) was neither air abraded nor contaminated. The first two groups were di- vided into 4 subgroups (N = 16) according to the cleaning method: ultrasonic bath in 99% isopropanol, use of a cleaning suspension of zirconium oxide particles, use of a cleaning suspension based on 10-MDP salt, and treatment with atmo- spheric plasma. The third group was divided into 2 subgroups (N = 16): treatment with atmospheric plasma and no treat- ment. All CoCr specimens were bonded to plexiglas tubes filled with a bonding resin that contained phosphate monomer. Tensile bond strength (TBS) was examined by tensile testing after 3 and 150 days of water storage plus 37,500 thermal cy- cles (N = 8). RESULTS: After contamination, TBS was significantly reduced after 150 days of water storage. Groups without air abrasion showed initially low TBS and debonded spontaneously after 150 days of water storage. CONCLUSION: None of the cleaning methods was able to remove saliva and silicone disclosing agent on CoCr-alloy sur- faces. Surface activation by plasma treatment has no long-term effect on the bond strength.

Quantifying 209 Polychlorinated Biphenyl Congeners in Silicone Wristbands to Evaluate Differences in Exposure among Demolition Workers.

A social housing estate in Denmark was designated for demolition due to exceedance of guidance values for polychlorinated biphenyls (PCBs) in indoor air. Here, we deployed precleaned silicone wristbands (n = 46) among demolition workers of these contaminated buildings during single workdays while conducting various work tasks. We established a method to analyze all 209 PCBs in wristbands to identify prominent congeners of exposure and evaluate differences between tasks. Wristbands were extracted using microwave-assisted extraction and then concentrated for gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. Twenty-nine chromatographic peaks representing 37 congeners were detected in every wristband, and tetra-CBs were the dominant homologue group. PCB-66, -44, and -70 were the most abundant congeners measured in worker wristbands, none of which are included within the typical seven indicator or WHO 12 PCBs. Workers who cut PCB-containing sealants had wristbands with the highest PCB concentrations (geometric mean ∑209PCBs = 1963 ng/g wristband), which were followed by those handling concrete elements on the building roof. Additionally, wristbands captured a broader range of PCBs than has been previously measured in air and serum samples. Taken together, our results highlight the importance of total congener analysis in assessing current PCB exposure in demolition work and the utility of wristbands for assessing these exposures.

Ongoing Laboratory Performance Study on Chemical Analysis of Hydrophobic and Hydrophilic Compounds in Three Aquatic Passive Samplers.

The quality of chemical analysis is an important aspect of passive sampling-based environmental assessments. The present study reports on a proficiency testing program for the chemical analysis of hydrophobic organic compounds in silicone and low-density polyethylene (LDPE) passive samplers and hydrophilic compounds in polar organic chemical integrative samplers. The median between-laboratory coefficients of variation (CVs) of hydrophobic compound concentrations in the polymer phase were 33% (silicone) and 38% (LDPE), similar to the CVs obtained in four earlier rounds of this program. The median CV over all rounds was 32%. Much higher variabilities were observed for hydrophilic compound concentrations in the sorbent: 50% for the untransformed data and a factor of 1.6 after log transformation. Limiting the data to the best performing laboratories did not result in less variability. Data quality for hydrophilic compounds was only weakly related to the use of structurally identical internal standards and was unrelated to the choice of extraction solvent and extraction time. Standard deviations of the aqueous concentration estimates for hydrophobic compound sampling by the best performing laboratories were 0.21 log units for silicone and 0.27 log units for LDPE (factors of 1.6 to 1.9). The implications are that proficiency testing programs may give more realistic estimates of uncertainties in chemical analysis than within-laboratory quality control programs and that these high uncertainties should be taken into account in environmental assessments.

Local hyperthermia mediated by gold nanoparticle-integrated silicone-covered stent: feasibility and tissue response in a rat esophageal model.

BACKGROUND: To assess the feasibility and tissue response of using a gold nanoparticle (AuNP)-integrated silicone-covered self-expandable metal stent (SEMS) for local hyperthermia in a rat esophageal model. METHODS: The study involved 42 Sprague-Dawley rats. Initially, 6 animals were subjected to near-infrared (NIR) laser irradiation (power output from 0.2 to 2.4 W) to assess the in vitro heating characteristics of the AuNP-integrated SEMS immediately after its placement. The surface temperature of the stented esophagus was then measured using an infrared thermal camera before euthanizing the animals. Subsequently, the remaining 36 animals were randomly divided into 4 groups of 9 each. Groups A and B received AuNP-integrated SEMS, while groups C and D received conventional SEMS. On day 14, groups A and C underwent NIR laser irradiation at a power output of 1.6 W for 2 min. By days 15 (3 animals per group) or 28 (6 animals per group), all groups were euthanized for gross, histological, and immunohistochemical analysis. RESULTS: Under NIR laser irradiation, the surface temperature of the stented esophagus quickly increased to a steady-state level. The surface temperature of the stented esophagus increased proportionally with power outputs, being 47.3 ± 1.4 °C (mean ± standard deviation) at 1.6 W. Only group A attained full circumferential heating through all layers, from the epithelium to the muscularis propria, demonstrating marked apoptosis in these layers without noticeable necroptosis. CONCLUSIONS: Local hyperthermia using the AuNP-integrated silicone-covered SEMS was feasible and induced cell death through apoptosis in a rat esophageal model. RELEVANCE STATEMENT: A gold nanoparticle-integrated silicone-covered self-expanding metal stent has been developed to mediate local hyperthermia. This approach holds potential for irreversibly damaging cancer cells, improving the sensitivity of cancer cells to therapies, and triggering systemic anticancer immune responses. KEY POINTS: • A gold nanoparticle-integrated silicone-covered self-expanding metal stent was placed in the rat esophagus. • Upon near-infrared laser irradiation, this stent quickly increased the temperature of the stented esophagus. • Local hyperthermia using this stent was feasible and resulted in cell death through apoptosis.

Silicone implant surface microtopography modulates inflammation and tissue repair in capsular fibrosis.

Excessive fibrous capsule formation around silicone mammary implants (SMI) involves immune reactions to silicone. Capsular fibrosis, a common SMI complication linked to host responses, worsens with specific implant topographies. Our study with 10 patients investigated intra- and inter-individually, reduced surface roughness effects on disease progression, wound responses, chronic inflammation, and capsular composition. The results illuminate the significant impact of surface roughness on acute inflammatory responses, fibrinogen accumulation, and the subsequent fibrotic cascade. The reduction of surface roughness to an average roughness of 4 µm emerges as a promising approach for mitigating detrimental immune reactions, promoting healthy wound healing, and curbing excessive fibrosis. The identified proteins adhering to rougher surfaces shed light on potential mediators of pro-inflammatory and pro-fibrotic processes, further emphasizing the need for meticulous consideration of surface design. The composition of the implant capsule and the discovery of intracapsular HSP60 expression highlight the intricate web of stress responses and immune activation that can impact long-term tissue outcomes.

Silicone cryogel skeletons enhance the survival and mechanical integrity of hydrogel-encapsulated cell therapies.

The transplantation of engineered cells that secrete therapeutic proteins presents a promising method for addressing a range of chronic diseases. However, hydrogels used to encase and protect non-autologous cells from immune rejection often suffer from poor mechanical properties, insufficient oxygenation, and fibrotic encapsulation. Here, we introduce a composite encapsulation system comprising an oxygen-permeable silicone cryogel skeleton, a hydrogel matrix, and a fibrosis-resistant polymer coating. Cryogel skeletons enhance the fracture toughness of conventional alginate hydrogels by 23-fold and oxygen diffusion by 2.8-fold, effectively mitigating both implant fracture and hypoxia of encapsulated cells. Composite implants containing xenogeneic cells engineered to secrete erythropoietin significantly outperform unsupported alginate implants in therapeutic delivery over 8 weeks in immunocompetent mice. By improving mechanical resiliency and sustaining denser cell populations, silicone cryogel skeletons enable more durable and miniaturized therapeutic implants.

Research Progress in Structure Synthesis, Properties, and Applications of Small-Molecule Silicone Surfactants.

Silicone surfactants have garnered significant research attention owing to their superior properties, such as wettability, ductility, and permeability. Small-molecular silicone surfactants with simple molecular structures outperform polymeric silicone surfactants in terms of surface activity, emulsification, wetting, foaming, and other areas. Moreover, silicone surfactants with small molecules exhibit a diverse and rich molecular structure. This review discusses various synthetic routes for the synthesis of different classes of surfactants, including single-chain, "umbrella" structure, double chain, bolaform, Gemini, and stimulus-responsive surfactants. The fundamental surface/interface properties of the synthesized surfactants are also highlighted. Additionally, these surfactants have demonstrated enormous potential in agricultural synergism, drug delivery, mineral flotation, enhanced oil recovery, separation, and extraction, and foam fire-fighting.

[A randomized controlled trial on the effect of early eschar dermabrasion combined with antimicrobial soft silicone foam dressing in the treatment of deep partial-thickness burn wounds in children].

Objective: To explore the effect of early eschar dermabrasion combined with antimicrobial soft silicone foam dressing (hereinafter referred to as foam dressing) in treating the deep partial-thickness burn wounds in children. Methods: This study was a randomized controlled trial. From June 2021 to December 2022, 78 pediatric patients with deep partial-thickness burns who met the inclusion criteria were admitted to the Department of Burns in Guiyang Steel Plant Employees Hospital. According to the random number table, the pediatric patients were divided into two groups, with 38 cases left in combined treatment group (with 20 males and 18 females, aged 26.00 (16.75, 39.75) months) and 39 cases in foam dressing group (with 21 males and 18 females, aged 19.00 (14.00, 31.00) months) after the exclusion of one dropped-out child in follow-up. The pediatric patients in combined treatment group underwent eschar dermabrasion of the wound within 48 hours after injury, the wound was covered with foam dressing after operation, and the dressing was replaced once every 7 days; for the pediatric patients in foam dressing group, the wound was sterilized within 48 hours after injury and covered with foam dressing, and the dressing was replaced once every 2 to 3 days. After the wound healing, the children in both groups were routinely applied with silicone gel twice a day for 3 weeks before started wearing elastic sleeves for more than 18 hours a day, and continuously for over than 6 months. The degree of pain during dressing change was evaluated using the children's pain behavior inventory FLACC. The adverse reactions during the treatment period, number of dressing changes, and wound healing time were observed and recorded. Six months after wound healing, the Vancouver scar scale (VSS) was used to evaluate the condition of the wound scar. Results: When changing dressing, the FLACC score for pain of pediatric patients in combined treatment group was 3.5 (2.0, 5.0), which was significantly lower than 6.0 (5.0, 8.0) in foam dressing group (Z=-5.40, P<0.05). During the treatment period, no adverse reactions such as wound edema, fluid accumulation, or peripheral skin rash allergies occurred in any pediatric patient in both groups. The number of dressing changes of pediatric patients in combined treatment group was 3 (3, 4) times, which was significantly less than 8 (7, 10) times in foam dressing group (Z=-7.58, P<0.05). The wound healing time of pediatric patients in combined treatment group was (19±5) days, which was significantly shorter than (25±6) days in foam dressing group (t=-4.48, P<0.05). Six months after wound healing, the VSS score for scar of pediatric patients in combined treatment group was 5 (2, 8), which was significantly lower than 7 (5, 10) in foam dressing group (Z=-3.05, P<0.05). Conclusions: Compared with using foam dressings alone, early eschar dermabrasion combined with foam dressings can reduce the number of dressing changes, alleviate the pain during dressing changes, and shorten the wound healing time in treating children with deep partial-thickness burns, and effectively alleviate scar hyperplasia by combining with anti-scar treatment post burns.

Development of Nontargeted Workflow of Occupational Exposure by Infrared Ion Spectroscopy and Silicone Wristbands' Passive Sampling.

A new approach using orthogonal analytical techniques is developed for chemical identification. High resolution mass spectrometry and infrared ion spectroscopy are applied through a 5-level confidence paradigm to demonstrate the effectiveness of nontargeted workflow for the identification of hazardous organophosphates. Triphenyl phosphate is used as a surrogate organophosphate for occupational exposure, and silicone wristbands are used to represent personal samplers. Spectral data of a target compound is combined with spectral data of the sodium adduct and quantum chemical calculations to achieve a confirmed identification. Here, we demonstrate a nontargeted workflow that identifies organophosphate exposure and provides a mechanism for selecting validated methods for quantitative analyses.

Long-term outcome of permanent tracheostomy management in two brachycephalic dogs using a commercial and a three-dimensional-printed silicone stent.

OBJECTIVE: To report the long-term outcome of utilization of a silicone stent to support the management of a permanent tracheostomy. STUDY DESIGN: Short case series. ANIMALS: Two client-owned brachycephalic dogs. METHODS: Two brachycephalic dogs with stage III laryngeal collapse underwent permanent tracheostomy. After the tracheostomy had healed, a silicone stent was inserted to support the stoma and facilitate home care. One dog wore a commercially available silicone stent for the follow-up period of 2 years. For the dog in Case 2, a 3D-printed, medical-grade silicone stent with an increased length was designed, as the dog had developed skin sores from the commercial device. RESULTS: Both dogs tolerated the silicone stent well. Stent care was managed by the owners without need for assistance. They reported that the silicone stent facilitated cleaning of the stoma surroundings and that they felt an increased confidence in airway patency, as the device prevented the tracheal stoma from collapsing. In Case 1, tracheoscopy 1 year after first stent insertion revealed minimal visible changes to the tracheal stoma. In Case 2, the 3D printed silicone stent led to a remission of skin sores and the dog wore the device comfortably until succumbing to an unrelated disease 13 months later. CONCLUSION: The insertion of a silicone stent is a simple and cost-effective method to improve home care of dogs with permanent tracheostomy. Larger dogs, as in Case 2, may benefit from custom-designed 3D-printed stents.

[POST-COVID SYNDROME, SICK BUILDING SYNDROME, SILICONE BREAST SYNDROME, CHRONIC FATIGUE SYNDROME, FIBROMYALGIA; AUTOIMMUNITY TO THE AUTONOMIC NERVOUS SYSTEM].

INTRODUCTION: POST-COVID SYNDROME, SICK BUILDING SYNDROME, SILICONE BREAST SYNDROME, CHRONIC FATIGUE SYNDROME, FIBROMYALGIA; AUTOIMMUNITY TO THE AUTONOMIC NERVOUS SYSTEM.

Longitudinal Mapping of Personal Biotic and Abiotic Exposomes and Transcriptome in Underwater Confined Space Using Wearable Passive Samplers.

Silicone-based passive samplers, commonly paired with gas chromatography-mass spectrometry (GC-MS) analysis, are increasingly utilized for personal exposure assessments. However, its compatibility with the biotic exposome remains underexplored. In this study, we introduce the wearable silicone-based AirPie passive sampler, coupled with nontargeted liquid chromatography with high-resolution tandem mass spectrometry (LC-HRMS/MS), GC-HRMS, and metagenomic shotgun sequencing methods, offering a comprehensive view of personalized airborne biotic and abiotic exposomes. We applied the AirPie samplers to 19 participants in a unique deep underwater confined environment, annotating 4,390 chemical and 2,955 microbial exposures, integrated with corresponding transcriptomic data. We observed significant shifts in environmental exposure and gene expression upon entering this unique environment. We noted increased exposure to pollutants, such as benzenoids, polycyclic aromatic hydrocarbons (PAHs), opportunistic pathogens, and associated antibiotic-resistance genes (ARGs). Transcriptomic analyses revealed the activation of neurodegenerative disease-related pathways, mostly related to chemical exposure, and the repression of immune-related pathways, linked to both biological and chemical exposures. In summary, we provided a comprehensive, longitudinal exposome map of the unique environment and underscored the intricate linkages between external exposures and human health. We believe that the AirPie sampler and associated analytical methods will have broad applications in exposome and precision medicine.

Surface Topography, Microbial Adhesion, and Immune Responses in Silicone Mammary Implant-Associated Capsular Fibrosis.

Breast cancer is the most common cancer in women globally, often necessitating mastectomy and subsequent breast reconstruction. Silicone mammary implants (SMIs) play a pivotal role in breast reconstruction, yet their interaction with the host immune system and microbiome remains poorly understood. This study investigates the impact of SMI surface topography on host antimicrobial responses, wound proteome dynamics, and microbial colonization. Biological samples were collected from ten human patients undergoing breast reconstruction with SMIs. Mass spectrometry profiles were analyzed for acute and chronic wound proteomes, revealing a nuanced interplay between topography and antimicrobial response proteins. 16S rRNA sequencing assessed microbiome dynamics, unveiling topography-specific variations in microbial composition. Surface topography alterations influenced wound proteome composition. Microbiome analysis revealed heightened diversity around rougher SMIs, emphasizing topography-dependent microbial invasion. In vitro experiments confirmed staphylococcal adhesion, growth, and biofilm formation on SMI surfaces, with increased texture correlating positively with bacterial colonization. This comprehensive investigation highlights the intricate interplay between SMI topography, wound proteome dynamics, and microbial transmission. The findings contribute to understanding host-microbe interactions on SMI surfaces, essential for optimizing clinical applications and minimizing complications in breast reconstruction.

Endobronchial silicone spigot in prolonged air leaks: Nationwide study on outcomes and risk factors for treatment failure.

BACKGROUND: The endobronchial silicone spigot, also known as the endobronchial Watanabe spigot, is used in bronchoscopic interventions to manage prolonged pulmonary air leakage. However, the outcomes of this procedure have not been thoroughly investigated. METHODS: Using a Japanese national inpatient database from April 2014 to March 2022, we assessed the clinical characteristics and outcomes of all eligible patients who received the endobronchial spigot. We also investigated risk factors associated with treatment failure. Treatment failure was defined as in-hospital death or the need for surgery after bronchial occlusion. RESULTS: We analyzed data of 1095 patients who underwent bronchial occlusion using the endobronchial spigot. Among them, 252 patients (23.0%) died during hospitalization, and 403 patients (36.8%) experienced treatment failure. Factors associated with treatment failure included age between 85 and 94 years (odds ratio [OR] 1.83; 95% confidence intervals [CI], 1.04-3.21); male sex (OR 2.43; 95% CI, 1.44-4.11); low Barthel index score; comorbidities of interstitial pneumonia (OR 1.71; 95% CI, 1.18-2.48); antibiotics treatment (OR 1.45; 95% CI, 1.02-2.07); steroids treatment (OR 1.59; 95% CI, 1.07-2.36); and surgery prior to bronchial occlusion (OR 2.08; 95% CI, 1.29-3.35). In contrast, pleurodesis after bronchial occlusion (OR 0.49; 95% CI, 0.32-0.75), and admission to high-volume hospitals were inversely associated with treatment failure (OR 0.58; 95% CI, 0.37-0.90). CONCLUSIONS: The endobronchial Watanabe spigot could be a nonsurgical treatment option for patients with prolonged pulmonary air leaks. Our findings will help identify patients who may benefit from such bronchial interventions.

Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer.

BACKGROUND: Repositioning guides are commonly employed in clinical studies to ensure consistent tooth color measurements. Yet, their influence on measured color remains uncertain. OBJECTIVE: This study evaluated the impact of repositioning guides' color and usage on tooth color measurement using a clinical spectrophotometer. METHODOLOGY: In total, 18 volunteers participated in this study, in which the color of their upper left central incisor and upper left canine was measured with or without repositioning guides (control). The guides were made from pink, blue, or translucent silicone, as well as an acetate-based bleaching tray. Tooth color was measured in triplicates using a clinical spectrophotometer based on the CIELAB system. The standard deviations of these readings were used to estimate reproducibility, and color differences (ΔE00) between the measurements with guides and the control were calculated. RESULTS: Repositioning guides had a minimal effect on L* values and no effect on b* values. The use of pink silicone increased a* values, whereas blue or translucent silicone reduced them. Irrespective of the evaluated tooth, the lowest ΔE00 values were observed for the translucent silicone and bleaching tray. The usage of guides only affected data variability for the L* color coordinate. CONCLUSION: Using repositioning guides can significantly impact the precision of tooth color measurement with a clinical spectrophotometer.

Evaluation of the Mechanical Properties of 3D-Printed Post and Core Systems.

PURPOSE: To evaluate and compare the fracture resistance and elastic modulus of 3D-printed post and core systems and fiber posts and composite cores. MATERIALS AND METHODS: Endodontic treatment was performed on 30 mandibular premolars, and post space preparation was performed. The teeth were then randomly divided into two groups (n = 15 per group): the 3D-printed (3DP) group and the fiber post and composite core (FPC) group. In the FPC group, fiber posts (Cytec Blanco 43.604, Hahnenkratt) were bonded with resin cement (RelyX U200, 3M), and the composite core dimension was standardized with a silicone index. In the 3DP group, the impression of the post space for each specimen was taken with pattern resin (Pattern Resin, GC America), and the coronal core was produced with the same silicone index. The impressions of the posts and cores were scanned, and then the custom post and core structures were fabricated from permanent crown resin material (Permanent Crown Resin, Formlabs) with a 3D printer (Form3B, Formlabs). Specimens were subjected to load tests with a universal testing machine (M500-25AT, Testometric). After fracture occurred, the fracture force and elastic modulus were calculated. The data were analyzed by independent sample t test (α = .05) Results: There was no statistically significant difference between the two groups in terms of peak fracture force (P = .626) and elastic modulus (P = .125), and no catastrophic root fractures were observed in either group. CONCLUSIONS: The fracture resistance of endodontically treated teeth was not significantly influenced by the post material. 3D-printed, custom-made resin posts were as effective as fiber glass posts with regard to fracture resistance.