Model-Based Design to Enhance Neotissue Formation in Additively Manufactured Calcium-Phosphate-Based Scaffolds.

In biomaterial-based bone tissue engineering, optimizing scaffold structure and composition remains an active field of research. Additive manufacturing has enabled the production of custom designs in a variety of materials. This study aims to improve the design of calcium-phosphate-based additively manufactured scaffolds, the material of choice in oral bone regeneration, by using a combination of in silico and in vitro tools. Computer models are increasingly used to assist in design optimization by providing a rational way of merging different requirements into a single design. The starting point for this study was an in-house developed in silico model describing the in vitro formation of neotissue, i.e., cells and the extracellular matrix they produced. The level set method was applied to simulate the interface between the neotissue and the void space inside the scaffold pores. In order to calibrate the model, a custom disk-shaped scaffold was produced with prismatic canals of different geometries (circle, hexagon, square, triangle) and inner diameters (0.5 mm, 0.7 mm, 1 mm, 2 mm). The disks were produced with three biomaterials (hydroxyapatite, tricalcium phosphate, and a blend of both). After seeding with skeletal progenitor cells and a cell culture for up to 21 days, the extent of neotissue growth in the disks' canals was analyzed using fluorescence microscopy. The results clearly demonstrated that in the presence of calcium-phosphate-based materials, the curvature-based growth principle was maintained. Bayesian optimization was used to determine the model parameters for the different biomaterials used. Subsequently, the calibrated model was used to predict neotissue growth in a 3D gyroid structure. The predicted results were in line with the experimentally obtained ones, demonstrating the potential of the calibrated model to be used as a tool in the design and optimization of 3D-printed calcium-phosphate-based biomaterials for bone regeneration.

How Periodontitis or Periodontal Bacteria Can Influence Alzheimer's Disease Features? A Systematic Review of Pre-Clinical Studies.

BACKGROUND: The negative effects of periodontitis on systemic diseases, including diabetes, cardiovascular diseases, and Alzheimer's disease (AD), have been widely described. OBJECTIVE: This systematic review aimed to gather the current understanding of the pathophysiological mechanisms linking periodontitis to AD. METHODS: An electronic systematic search of the PubMed/MEDLINE, Scopus, and Embase databases was performed using the following PECO question: How can periodontitis or periodontal bacteria influence Alzheimer's disease features?". Only preclinical studies exploring the biological links between periodontitis and AD pathology were included. This study was registered at the International Prospective Register of Systematic Reviews (PROSPERO), and the Syrcle and Camarades protocols were used to assess the risk of bias. RESULTS: After a systematic screening of titles and abstracts (n = 3,307), thirty-six titles were selected for abstract reading, of which 13 were excluded (k = 1), resulting in the inclusion of 23 articles. Oral or systemic exposure to periodontopathogens or their byproducts is responsible for both in situ brain manifestations and systemic effects. Significant elevated rates of cytokines and amyloid peptides (Aß) and derivate products were found in both serum and brain. Additionally, in infected animals, hyperphosphorylation of tau protein, hippocampal microgliosis, and neuronal death were observed. Exposure to periodontal infection negatively impairs cognitive behavior, leading to memory decline. CONCLUSIONS: Systemic inflammation and brain metastatic infections induced by periodontal pathogens contribute to neuroinflammation, amyloidosis, and tau phosphorylation, leading to brain damage and subsequent cognitive impairment.

Effect of lab procedures and ultrasonic bath cleaning on customized implant abutment pollution: An in vitro study.

AIM: The aim of this study was to validate the effectiveness of a simplified ultrasonic cleaning protocol to clean customized abutments. The second purpose was to investigate the percentage of pollutants on customized abutments delivered by the implants company and the additional effect of dental laboratory manipulations. MATERIALS AND METHODS: Twenty-four customized abutments were divided in two groups, 12 returning from the implant company and 12 others returning from the dental laboratory. In each group, there were 6 zirconia (Zr02) abutments and 6 titanium (Ti) abutments. For each conditions, half of the samples were clean with the experimental protocol and the other were left as delivered by the company. The two steps cleaning protocol consisted of mechanical treatment with a sterile compress soaked in a detergent over the transgingival part of the abutment followed by 3 successive ultrasound baths for 2 min/bath. The presence of pollutants was quantified by scanning electron microscopy. RESULTS: The suggested cleaning method allowed to significantly decrease the quantity of pollutants (p=0.0006). The abutments returning from the dental laboratory were significantly more polluted than those coming directly from the implant company (p=0.0043). The cleaning effect was highly significant in both groups (p<0.0001). The quantity of pollutants before cleaning were similar in the titanium and in the zirconia groups and the cleaning effect was highly significant in both groups (p=0.0009). CONCLUSION: The tested cleaning protocol was successful on the customized abutments from each group.

One-stage versus two-stage piezocision-assisted orthodontic tooth movement: A preclinical study based on Nano-CT and RT-PCR analyses.

OBJECTIVE: To evaluate the effect of a second-stage piezocision on the biological response. MATERIALS AND METHODS: 60 rats were randomly allocated to 6 experimental groups of 10 rats. Rats undergoing a one-stage piezocision were sacrified on day 7, 28 and 42 (groups 1-3) while rats undergoing a two-satge piezocision were sacrified on day 42, 63 and 90 (groups 4-6), respectively. The biological response was investigated in 3D at the tissue level using Nano-computed tomography (Nano-CT) and, at the molecular level using the qRT-PCR technique. Bone Volume Fraction (BVF) loss was the primary endpoint. RESULTS: Similar loss of BVF were observed both after the first and second piezocisions. The change in BVF loss between 7 and 28 days after each piezocision were 25.1 ± 13.0 (SE)% and 11.2 ± 11.6 (SE)% respectively and did not differ from each other (p = 0.43). Changes in BVF loss from 7 to 42 days were also comparable in one-stage and two-stage piezocision (4.9 ± 12.3 (SE) vs. -19.9 ± 13.4 (SE), p = 0.19). At the molecular level, all parameters except Translating Ribosome Affinity Purification (TRAP) protein had identical patterns. CONCLUSION: Within the limits of the present study, a second piezocision allowed to re-induce the Regional Acceleratory Phenomenon (RAP) effect. Nevertheless, the relevance of the findings to the clinical effect has not been tested.

Disentangling the effects of CAD/CAM customized appliances and piezocision in orthodontic treatment.

OBJECTIVES: To discern the effects of computer-aided design (CAD)/computer-aided manufactured (CAM) customized appliances and piezocision on orthodontic treatment (OT). MATERIALS AND METHODS: The study combined findings from two previously published randomized controlled trials: (1) standard OT vs piezocision-assisted standard OT, and (2) CAD/CAM OT vs piezocision-assisted CAD/CAM OT. Piezocision is a minimally invasive corticotomy surgical procedure used to accelerate orthodontic treatment and CAD/CAM refers to CAD/CAM customized brackets and archwires. The outcomes were the overall treatment time, and the durations of the alignment phase and fine-tuning phase. Clinical and radiological features also were evaluated. RESULTS: The combined study included 48 patients with similar baseline characteristics. Compared to the standard treatment, CAD/CAM technology alone significantly decreased the overall median OT time from 543 to 394 days (P < .001) and from 543 to 254 days (P < .0001) when combined with piezocision. Although piezocision significantly reduced the duration of the alignment phase in the mandible and maxilla, CAD/CAM technology considerably shortened the fine-tuning phase. All periodontal and radiographic parameters remained stable from the start to the end of treatment in all groups. CONCLUSIONS: CAD/CAM technology combined with piezocision accelerates the entire OT process, during the alignment phase for piezocision and during the fine-tuning phase for CAD/CAM, with a global reduction of the overall treatment time of more than 50%.

Blood Biomarkers and Serologic Immunological Profiles Related to Periodontitis in Abdominal Aortic Aneurysm Patients.

BACKGROUND: Periodontitis is a chronic inflammatory gum disease associated with systemic diseases such as cardiovascular diseases. AIM: To investigate the association of systemic blood biomarkers, C-reactive protein (CRP), levels of lipopolysaccharide (LPS), and IgG levels against periodontal pathogens Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) with the stability, based on the aortic diameter, the growth rate and the eligibility for surgical intervention, of patients with abdominal aortic aneurysm (AAA). METHODS: Patients with stable AAA (n = 30) and unstable AAA (n = 31) were recruited. The anti-A. actinomycetemcomitans and anti-P. gingivalis IgG levels were analyzed by ELISA, the LPS analysis was performed by using the limulus amebocyte lysate (LAL) test, and plasma levels of CRP were determined using an immune turbidimetric method. The association between these blood systemic biomarkers, AAA features, periodontal clinical parameters and oral microbial profiles were explored. Regression models were used to test the relationship between variables. RESULTS: The presence of antibodies against Pg and Aa, LPS and high CRP concentrations were found in all AAA patients. The IgG levels were similar in patients with stable and unstable AAA (both for Aa and Pg). Among investigated blood biomarkers, only CRP was associated with AAA stability. The amount of LPS in saliva, supra, and subgingival plaque were significantly associated with the systemic LPS (p <0.05). CONCLUSIONS: This post-hoc study emphasizes the presence of antibodies against Pg and Aa, LPS and high CRP concentrations in all AAA patients. The presence of Pg in saliva and subgingival plaque was significantly associated with the blood LPS levels. For further studies investigating periodontitis and systemic diseases, specific predictive blood biomarkers should be considered instead of the use of antibodies alone.

In vitro and in vivo biocompatibility of calcium-phosphate scaffolds three-dimensional printed by stereolithography for bone regeneration.

Stereolithography (SLA) is an interesting manufacturing technology to overcome limitations of commercially available particulated biomaterials dedicated to intra-oral bone regeneration applications. The purpose of this study was to evaluate the in vitro and in vivo biocompatibility and osteoinductive properties of two calcium-phosphate (CaP)-based scaffolds manufactured by SLA three-dimensional (3D) printing. Pellets and macro-porous scaffolds were manufactured in pure hydroxyapatite (HA) and in biphasic CaP (HA:60-TCP:40). Physico-chemical characterization was performed using micro X-ray fluorescence, scanning electron microscopy (SEM), optical interferometry, and microtomography (µCT) analyses. Osteoblast-like MG-63 cells were used to evaluate the biocompatibility of the pellets in vitro with MTS assay and the cell morphology and growth characterized by SEM and DAPI-actin staining showed similar early behavior. For in vivo biocompatibility, newly formed bone and biodegradability of the experimental scaffolds were evaluated in a subperiosteal cranial rat model using µCT and descriptive histology. The histological analysis has not indicated evidences of inflammation but highlighted close contacts between newly formed bone and the experimental biomaterials revealing an excellent scaffold osseointegration. This study emphasizes the relevance of SLA 3D printing of CaP-based biomaterials for intra-oral bone regeneration even if manufacturing accuracy has to be improved and further experiments using biomimetic scaffolds should be conducted.

Human papillomavirus oncoproteins induce a reorganization of epithelial-associated γδ T cells promoting tumor formation.

It has been shown that γδ T cells protect against the formation of squamous cell carcinoma (SCC) in several models. However, the role of γδ T cells in human papillomavirus (HPV)-associated uterine cervical SCC, the third-leading cause of death by cancer in women, is unknown. Here, we investigated the impact of γδ T cells in a transgenic mouse model of carcinogenesis induced by HPV16 oncoproteins. Surprisingly, γδ T cells promoted the development of HPV16 oncoprotein-induced lesions. HPV16 oncoproteins induced a decrease in epidermal Skint1 expression and the associated antitumor Vγ5+ γδ T cells, which were replaced by γδ T-cell subsets (mainly Vγ6+ γδlowCCR2+CCR6-) actively producing IL-17A. Consistent with a proangiogenic role, γδ T cells promoted the formation of blood vessels in the dermis underlying the HPV-induced lesions. In human cervical biopsies, IL-17A+ γδ T cells could only be observed at the cancer stage (SCC), where HPV oncoproteins are highly expressed, supporting the clinical relevance of our observations in mice. Overall, our results suggest that HPV16 oncoproteins induce a reorganization of the local epithelial-associated γδ T-cell subpopulations, thereby promoting angiogenesis and cancer development.

Origin and immunoescape of uterine cervical cancer.

Human papillomavirus associated uterine cervical cancer is an important public health problem since it is classified as the fourth most common cancer in women worldwide with more than 500,000 recorded cases. This review is focused on where and why HPV infection induces cervical cancers and how this virus avoids the host immune response. Immunological therapeutic approaches are also addressed.