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Clinical Oral Implants Research Jun 2024The incorporation of retromolar bone grafts used for alveolar ridge augmentation is not well understood. This prospective observational study aims to supply...
OBJECTIVES
The incorporation of retromolar bone grafts used for alveolar ridge augmentation is not well understood. This prospective observational study aims to supply histomorphometrical data from bone graft biopsies taken at the time of retrieval and after a 3-month healing period using patient-matched biopsies.
MATERIALS AND METHODS
In 17 patients, trephine biopsies of the graft were acquired at the time of graft retrieval and after a 3-month healing period. The biopsies were compared histomorphometrically regarding the number of osteocytes, appearance of osteocyte lacunae, quantity, surface area, and activity of the Haversian canals.
RESULTS
All grafts appeared clinically stable after screw removal and 17 implants were placed. Histomorphometric analysis revealed no significant difference in the number of osteocytes (p = .413), osteocyte lacunae (p = .611), the ratio of filled/empty osteocyte lacunae (p = .467) and active Haversian canals (p = .495) between the biopsies retrieved after a 3-months healing period with those at the time of grafting. The only significant difference was noted in the mean surface area of the Haversian canals (p = .002). Specifically, the grafts post 3-month healing showed a significantly larger mean area (0.069 mm) compared to the time of grafting (0.029 mm).
CONCLUSION
This study demonstrates, compared to other data, a high rate of vital structures in retromolar bone block grafts after 3 months of healing, exhibiting the same histological features in comparison to the biopsies from the native alveolar ridge. Standard histomorphometrical parameters, e.g., the amount of filled or empty osteocyte lacunae for the description of the vitality of the graft need to be reappraised.
PubMed: 38847078
DOI: 10.1111/clr.14306 -
Frontiers in Dental Medicine 2024Peri-implantitis is a complex infectious disease that manifests as progressive loss of alveolar bone around the dental implants and hyper-inflammation associated with...
Peri-implantitis is a complex infectious disease that manifests as progressive loss of alveolar bone around the dental implants and hyper-inflammation associated with microbial dysbiosis. Using antibiotics in treating peri-implantitis is controversial because of antibiotic resistance threats, the non-selective suppression of pathogens and commensals within the microbial community, and potentially serious systemic sequelae. Therefore, conventional treatment for peri-implantitis comprises mechanical debridement by nonsurgical or surgical approaches with adjunct local microbicidal agents. Consequently, current treatment options may not prevent relapses, as the pathogens either remain unaffected or quickly re-emerge after treatment. Successful mitigation of disease progression in peri-implantitis requires a specific mode of treatment capable of targeting keystone pathogens and restoring bacterial community balance toward commensal species. Antimicrobial peptides (AMPs) hold promise as alternative therapeutics through their bacterial specificity and targeted inhibitory activity. However, peptide sequence space exhibits complex relationships such as sparse vector encoding of sequences, including combinatorial and discrete functions describing peptide antimicrobial activity. In this paper, we generated a transparent Machine Learning (ML) model that identifies sequence-function relationships based on rough set theory using simple summaries of the hydropathic features of AMPs. Comparing the hydropathic features of peptides according to their differential activity for different classes of bacteria empowered predictability of antimicrobial targeting. Enriching the sequence diversity by a genetic algorithm, we generated numerous candidate AMPs designed for selectively targeting pathogens and predicted their activity using classifying rough sets. Empirical growth inhibition data is iteratively fed back into our ML training to generate new peptides, resulting in increasingly more rigorous rules for which peptides match targeted inhibition levels for specific bacterial strains. The subsequent top scoring candidates were empirically tested for their inhibition against keystone and accessory peri-implantitis pathogens as well as an oral commensal bacterium. A novel peptide, VL-13, was confirmed to be selectively active against a keystone pathogen. Considering the continually increasing number of oral implants placed each year and the complexity of the disease progression, prevalence of peri-implant diseases continues to rise. Our approach offers transparent ML-enabled paths towards developing antimicrobial peptide-based therapies targeting the changes in the microbial communities that can beneficially impact disease progression.
PubMed: 38846578
DOI: 10.3389/fdmed.2024.1372534 -
Frontiers in Immunology 2024Although many studies have underscored the importance of T cells, phenotypically and functionally, fewer have studied the functions of myeloid cells in COVID disease. In...
INTRODUCTION
Although many studies have underscored the importance of T cells, phenotypically and functionally, fewer have studied the functions of myeloid cells in COVID disease. In particular, the potential role of myeloid cells such as monocytes and low-density neutrophils (LDNs) in innate responses and particular in the defense against secondary bacterial infections has been much less documented.
METHODS
Here, we compared, in a longitudinal study, healthy subjects, idiopathic fibrosis patients, COVID patients who were either hospitalized/moderate (M-) or admitted to ICU (COV-ICU) and patients in ICU hospitalized for other reasons (non-COV-ICU).
RESULTS
We show that COVID patients have an increased proportion of low-density neutrophils (LDNs), which produce high levels of proteases (particularly, NE, MMP-8 and MMP-9) (unlike non-COV-ICU patients), which are partly responsible for causing type II alveolar cell damage in co-culture experiments. In addition, we showed that M- and ICU-COVID monocytes had reduced responsiveness towards further live (PAO1 strain) infection, an important pathogen colonizing COVID patients in ICU, as assessed by an impaired secretion of myeloid cytokines (IL-1, TNF, IL-8,…). By contrast, lymphoid cytokines (in particular type 2/type 3) levels remained high, both basally and post PAO1 infection, as reflected by the unimpaired capacity of T cells to proliferate, when stimulated with anti-CD3/CD28 beads.
DISCUSSION
Overall, our results demonstrate that COVID circulatory T cells have a biased type 2/3 phenotype, unconducive to proper anti-viral responses and that myeloid cells have a dual deleterious phenotype, through their LDN-mediated damaging effect on alveolar cells and their impaired responsiveness (monocyte-mediated) towards bacterial pathogens such as .
Topics: Humans; COVID-19; Pseudomonas aeruginosa; Monocytes; Male; Female; Middle Aged; SARS-CoV-2; Pseudomonas Infections; Neutrophils; Aged; Cytokines; Adult; Longitudinal Studies; Leukocytes, Mononuclear; Lung
PubMed: 38835759
DOI: 10.3389/fimmu.2024.1398369 -
BioRxiv : the Preprint Server For... May 2024One of the defining features of apicomplexan parasites is their cytoskeleton composed of alveolar vesicles, known as the inner membrane complex (IMC) undergirded by...
One of the defining features of apicomplexan parasites is their cytoskeleton composed of alveolar vesicles, known as the inner membrane complex (IMC) undergirded by intermediate-like filament network and an array of subpellicular microtubules (SPMTs). In , this specialized cytoskeleton is involved in all aspects of the disease-causing lytic cycle, and notably acting as a scaffold for parasite offspring in the internal budding process. Despite advances in our understanding of the architecture and molecular composition, insights pertaining to the coordinated assembly of the scaffold are still largely elusive. Here, tachyzoites were dissected by advanced, iterative expansion microscopy (pan-ExM) revealing new insights into the very early sequential formation steps of the tubulin scaffold. A comparative study of the related parasite revealed that different MT bundling organizations of the nascent SPMTs correlate with the number of central and basal alveolar vesicles. In absence of a so far identified MT nucleation mechanism, we genetically dissected γ-tubulin and γ-tubulin complex protein 4 (GCP4). While γ-tubulin depletion abolished the formation of the tubulin scaffold, a set of MTs still formed that suggests SPMTs are nucleated at the outer core of the centrosome. Depletion of GCP4 interfered with the correct assembly of SPMTs into the forming daughter buds, further indicating that the parasite utilizes the γ-tubulin complex in tubulin scaffold formation .
PubMed: 38826480
DOI: 10.1101/2024.05.25.595886 -
Clinical Oral Investigations Jun 2024This study aimed to assess membrane use with a bone substitute graft for guided bone regeneration (GBR) in experimental dehiscence defects.
The effect of a barrier membrane on the incorporation of deproteinized bovine bone mineral (DBBM) in experimental defects at the time of early implant placement. A preclinical study.
OBJECTIVES
This study aimed to assess membrane use with a bone substitute graft for guided bone regeneration (GBR) in experimental dehiscence defects.
MATERIALS AND METHODS
Maxillary second incisors (I2) in 9 dogs were extracted. Six weeks later, implants were inserted and experimental dehiscence defects (5 × 3 mm) created on the buccal aspect. The defects and surrounding bone were grafted with deproteinized bovine bone mineral. One side (test) was covered with a resorbable collagen membrane whereas the contralateral side (control) was not. After 6 weeks, histomorphometrical analysis was performed to evaluate: (a) first bone-to-implant contact (fBIC), (b) buccal bone thickness at 1 mm increments from implant shoulder, (c) regenerated area (RA), (d) area and percentages of new bone (B), bone substitute (BS) and mineralized tissue (MT).
RESULTS
The histological appearance was similar between test and control sites. At central and lateral sections, there were no differences between groups for fBIC, buccal bone thickness, RA, BS, B, %B, MT and %MT. At central sections, membrane use favoured more %BS and %MT (p = 0.052). There was significantly more B, %B and MT at lateral compared to central sections.
CONCLUSIONS
Membrane use tended to retain more bone substitute, but had no effect on new bone ingrowth. Lateral sections showed significantly more bone ingrowth and mineralized tissue compared to central sections, confirming that new bone ingrowth takes place mainly from the lateral walls of the defect.
CLINICAL RELEVANCE
Preclinical research to clarify the dynamics of bone regeneration in GBR procedures is relevant in clinical practice.
Topics: Animals; Cattle; Dogs; Bone Substitutes; Membranes, Artificial; Bone Regeneration; Incisor; Guided Tissue Regeneration, Periodontal; Maxilla; Dental Implants; Collagen; Surgical Wound Dehiscence; Minerals
PubMed: 38822921
DOI: 10.1007/s00784-024-05748-6 -
World Journal of Stem Cells May 2024Alveolar bone defects caused by inflammation are an urgent issue in oral implant surgery that must be solved. Regulating the various phenotypes of macrophages to enhance...
BACKGROUND
Alveolar bone defects caused by inflammation are an urgent issue in oral implant surgery that must be solved. Regulating the various phenotypes of macrophages to enhance the inflammatory environment can significantly affect the progression of diseases and tissue engineering repair process.
AIM
To assess the influence of interleukin-10 (IL-10) on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) following their interaction with macrophages in an inflammatory environment.
METHODS
IL-10 modulates the differentiation of peritoneal macrophages in Wistar rats in an inflammatory environment. In this study, we investigated its impact on the proliferation, migration, and osteogenesis of BMSCs. The expression levels of signal transducer and activator of transcription 3 (STAT3) and its activated form, phosphorylated-STAT3, were examined in IL-10-stimulated macrophages. Subsequently, a specific STAT3 signaling inhibitor was used to impede STAT3 signal activation to further investigate the role of STAT3 signaling.
RESULTS
IL-10-stimulated macrophages underwent polarization to the M2 type through substitution, and these M2 macrophages actively facilitated the osteogenic differentiation of BMSCs. Mechanistically, STAT3 signaling plays a crucial role in the process by which IL-10 influences macrophages. Specifically, IL-10 stimulated the activation of the STAT3 signaling pathway and reduced the macrophage inflammatory response, as evidenced by its diminished impact on the osteogenic differentiation of BMSCs.
CONCLUSION
Stimulating macrophages with IL-10 proved effective in improving the inflammatory environment and promoting the osteogenic differentiation of BMSCs. The IL-10/STAT3 signaling pathway has emerged as a key regulator in the macrophage-mediated control of BMSCs' osteogenic differentiation.
PubMed: 38817327
DOI: 10.4252/wjsc.v16.i5.560 -
Advances in Physiology Education Sep 2024The movement of air into and out of the lungs is facilitated by changes in pressure within the thoracic cavity relative to atmospheric pressure, as well as the...
The movement of air into and out of the lungs is facilitated by changes in pressure within the thoracic cavity relative to atmospheric pressure, as well as the resistance encountered by airways. In this process, the movement of air into and out of the lungs is driven by pressure gradients established by changes in lung volume and intra-alveolar pressure. However, pressure never sucks! The concept that pressure never sucks, pressure only pushes encapsulates a fundamental principle in the behavior of gases. This concept challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we explore the essence of this concept and its applications in pulmonary ventilation. Pressure is one of the most important concepts in physics and physiology. Atmospheric pressure at sea level is equal to 1 atmosphere or around 101,325 Pascal [Pa (1 Pa = 1 N/m)]. This huge pressure is pushing down on everything all the time. However, this pressure is difficult to understand because we do not often observe the power of this incredible force. We used five readily available, simple, and inexpensive demonstrations to introduce the physics and power of pressure. This extraordinarily complex physics concept was approached in a straightforward and inexpensive manner while still providing an understanding of the fundamental concepts. These simple demonstrations introduced basic concepts and addressed common misconceptions about pressure. The concept that pressure never sucks, pressure only pushes challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we will explore the essence of this concept and its applications in pulmonary ventilation. Specifically, we used five readily available, simple, inexpensive demonstrations to introduce the physics and power of pressure.
Topics: Humans; Pressure; Physiology; Lung; Pulmonary Ventilation
PubMed: 38813605
DOI: 10.1152/advan.00066.2024 -
International Journal of Surgery Case... Jul 2024The soft tissue volume and its stability around dental implants are important for the final aesthetic outcome.
INTRODUCTION AND IMPORTANCE
The soft tissue volume and its stability around dental implants are important for the final aesthetic outcome.
CASE PRESENTATION
A 39-year-old female was referred for dental implant placement for her missing tooth. Following attachment of the cover screw VCMX was used to simultaneously augment buccal ridge defect. Patient was seen 2 weeks after surgery for follow up where sutures were removed. After 3 months, patient received her final crown and been on follow up for 9 months where a successful well-functioning restoration with clinically healthy soft tissue and optimal profilometric outcome were maintained.
CLINICAL DISCUSSION
This approach is relatively simple, less invasive and time saving as it eliminates the need for another surgical donor site to manage the defect.
CONCLUSIONS
The present report showed that VCMX was effective in soft tissue augmentation at implant sites in aesthetic zone.
CLINICAL RELEVANCE
Within the limits of this study, the positive results suggest that the volume stable collagen matrix (VCMX) may be a reliable option in treatment of siebert class I ridge defects. VCMX was associated with less amount of pain or discomfort and reduced patient morbidity.
PubMed: 38805839
DOI: 10.1016/j.ijscr.2024.109792 -
International Journal of Implant... May 2024Particulate bovine bone substitutes (BS) are commonly used in oral regeneration. However, more literature is needed focusing on comparative analyses among various... (Review)
Review Comparative Study
PURPOSE
Particulate bovine bone substitutes (BS) are commonly used in oral regeneration. However, more literature is needed focusing on comparative analyses among various particulate bovine BS. This study evaluates pre-clinical and clinical data of different particulate bovine BS in oral regeneration.
METHODS
A narrative review was conducted by screening the PubMed database Included in the review were pre-clinical and clinical studies until 2024 comparing a minimum of two distinct particulate bovine BS. In addition to examining general data concerning manufacturing and treatment processes, biological safety, physical and chemical characteristics, and graft resorption, particular emphasis was placed on assessing pre-clinical and clinical data related to ridge preservation, sinus floor elevation, peri-implant defects, and various forms of alveolar ridge augmentation utilizing particulate bovine BS.
RESULTS
Various treatment temperatures ranging from 300 to 1,250 °C and the employment of chemical cleaning steps were identified for the manufacturing process of particulate bovine BS deemed to possess biosecurity. A notable heterogeneity was observed in the physical and chemical characteristics of particulate bovine BS, with minimal or negligible graft resorption. Variations were evident in particle and pore sizes and the porosity of particulate bovine BS. Pre-clinical assessments noted a marginal inclination towards favorable outcomes for particulate bovine BS subjected to higher treatment temperatures. However, clinical data are insufficient. No distinctions were observed regarding ridge preservation, while slight advantages were noted for high-temperature treated particulate bovine BS in sinus floor elevation.
CONCLUSIONS
Subtle variances in both pre-clinical and clinical outcomes were observed in across various particulate bovine BS. Due to inadequate data, numerous considerations related to diverse particulate bovine BS, including peri-implant defects, must be more conclusive. Additional clinical studies are imperative to address these knowledge gaps effectively.
Topics: Cattle; Animals; Bone Substitutes; Humans; Alveolar Ridge Augmentation; Bone Regeneration
PubMed: 38801622
DOI: 10.1186/s40729-024-00544-z -
Cureus Apr 2024In edentulous arches, alveolar ridge atrophy after tooth extraction is a common problem that affects patient comfort and quality of life. Implant-supported fixed...
In edentulous arches, alveolar ridge atrophy after tooth extraction is a common problem that affects patient comfort and quality of life. Implant-supported fixed restorations are a well-proven treatment option for edentulism. The concepts of implant dentistry have developed over time to produce better aesthetics and functional results. To reduce cantilever length and enable prostheses with 12 teeth, the all-on-four technique entails inserting two anterior implants axially and distally orienting two posterior implants. Compared to conventional loading, immediate loading offers various benefits without compromising quality. An instantaneous fixed provisional allows patients immediate function and preserves their quality of life while also promoting a high degree of patient satisfaction in terms of aesthetics, phonetics, mastication, and psychological comfort.
PubMed: 38800271
DOI: 10.7759/cureus.58919