Fixation Pins Increase the Accuracy of Implant Surgery in Free-End Models: An In Vitro Study.

PURPOSE: Implant surgical guides, in combination with implant planning software, have been designed for accurate surgery, especially in partial edentulism. The purpose of this study was to examine the effect of fixation pins of surgical guides on the accuracy of static computer-assisted implant surgeries in a maxillary free-end situation. MATERIALS AND METHODS: This in vitro study was conducted to compare surgical guides using various fixation pin protocols in implant surgery. A patient dental model with missing teeth from maxillary right first premolar to third molar was used as the study model… Implant placement was planned at maxillary right first premolar, right first molar, and right second molar; Straumann full guide templates were designed and fabricated using the coDiagnostiX software. The experiment involved surgical guides with no fixation pins (NF), buccal unilateral fixation pin (BF), palatal unilateral fixation pin (PF), and bilateral fixation pins on the buccal and palatal sides (BPF), based on the position and number of fixation pins. The deviation between the actual and planned positions was used to evaluate implant accuracy. The fixation pin protocols were the primary predictive variables. Angular, 3D platform, and 3D apex deviations were the primary outcome variables. Statistical analysis was performed using the one-way analysis of variance and Tukey's test (α = 0.05). RESULTS: NF generated the maximum angular deviation (3.65 ± 1.39°), 3D platform deviation (1.58 ± 0.55 mm), and 3D apex deviation (2.18 ± 0.79 mm), whereas BPF produced the minimum angular deviation (1.88 ± 0.86°), 3D platform deviation (1.09 ± 0.51 mm), and 3D apex deviation (1.53 ± 0.45 mm). A statistically significant difference between NF and BPF in the angular deviation, 3D platform, and apex deviation (P < .0001, P = .009, and P = .002, respectively) was identified. The unilateral fixation pin exerted a significant effect only on the angular accuracy (BF, P = .0018; PF, P = .0001). CONCLUSION: In a maxillary free-end situation, templates with a fixation pin generate better implant accuracy than those without it. A bilateral fixation pin protocol may produce less deviation than those without fixation pins. The implant accuracy does not appear to be affected by the position of the unilateral fixation pin.

Adhesive Ability of Different Oral Pathogens to Various Dental Materials: An In Vitro Study.

Introduction: In dental treatments, the reason for secondary caries and the failure of root canal treatment is the microbial infection, which concerns most dentists. The challenge of how to reduce the number of bacteria at the filling materials and the number of residual bacteria in the root canal has become a research hotspot. In this study, the bacterial adhesion properties of several common dental materials were compared to provide a theoretical basis for the selection of antibacterial properties of dental materials. Methodology. Three commonly used dental restorative materials and five sealers in root canal treatment were selected. Each material block was immersed in the corresponding supragingival (Streptococcus mutans and Actinomyces viscosus) or subgingival (Porphyromonas gingivalis and Enterococcus faecalis) bacterial solution and cultured under anaerobic conditions at 37°C for 2, 4, 6, 8, 12, 16, 20, and 24 h. The adhesion of bacteria was observed, and the number of different bacteria adhering to various material model disks was calculated at different time intervals under a scanning electron microscope. The adherent CFU load of the materials was determined by colony counting. Results: Streptococcus mutans and Actinomyces viscosus exhibited the strongest adhesion ability to the resin material blocks. Porphyromonas gingivalis and Enterococcus faecalis exhibited the highest adhesion ability to the AH-Plus sealer block. Conclusions: In dental treatments, dental materials should be selected based on the chemical, physical, and biological properties of materials. In addition, it is necessary to develop new antibacterial dental materials.

pH and Thermo Dual-Responsive Fluorescent Hydrogel Actuator.

As one of the most important smart materials, fluorescent hydrogel actuators can produce both color and shape changes under external stimuli. In the present work, an effective approach to develop a novel fluorescent hydrogel actuator with pH and thermo dual responsiveness is proposed. Through incorporating pH-responsive perylene tetracarboxylic acid (PTCA), which is a typical fluorescent moiety with aggregation-caused quenching (ACQ) effect, into an anisotropic poly(N-isopropylacrylamide)-polyacrylamide (PNIPAm-PAAm) structure, the obtained hydrogel exhibits stable thermoresponsive shape deformation and switchable fluorescence performance upon a pH trigger. Therefore, fluorescence-quenching-based and actuation-based information can be revealed when exposed to UV light and immersed into warm water, respectively. Moreover, the thermoresponsive actuating behavior can be applied to further hide the fluorescence-quenching-based images. The present work may provide new insights into the design and preparation of novel stimuli-responsive hydrogel actuators.

[Three-dimensional finite element analysis of influence of occlusal surface height on stress distribution around posterior implant-supported single crown].

OBJECTIVE: To evaluate the effect of the occlusal surface height of a mandibular posterior implant-supported single crown on stress in bone tissues. METHODS: Three-dimensional finite element models of the implant-supported single crown replacing the missing right lower second premolar, mesial and distal natural teeth, periodontal membrane, alveolar bone, loaded rigid body and analog food of almond were established. Using the Federation Dentaire International (FDI) system, the first premolar, the second premolar and the first molar were represented with 44, 45, 46. Three occlusal surface heights of the crown were studied: (1) normal height; (2) 15 µm reduction in height; (3) 30 µm reduction in height. The models were loaded by independent loading with maximal occlusal force(44 by 280 N, 45 by 360 N, and 46 by 480 N) and average occlusal force(44 by 140 N, 45 by 180 N, and 46 by 240 N)on the single crown; combined loading (maximal occlusal force transformed into uniform load of 3.7 MPa on top of rigid body, in contact with points on the occlusal surface), and analog almond-like food loading (average occlusal force transformed into uniform load of 1.67 MPa in simulated food chewing, in contact with points on the occlusal surface). RESULTS: For maximal biting force under independent loading, Von Mises stress peak values in bone tissues around 44, 45, and 46 were 82.57 MPa, 45.26 MPa and 27.79 MPa; For average biting force, peak values were 41.28 MPa, 22.63 MPa and 13.89 MPa. Under combined loading, compared with the normal occlusal surface height group, Von Mises stress peak values decreased 4.6 MPa, by 0.84%; increased 7.52 MPa, by 20.04%, and decreased 1.8 MPa, by 5.84%, for 45, 46, and 44 in the 30 µm infra-occlusion group, respectively. Under food loading, Von Mises stress peak values decreased 0.34 MPa, by 1.62%; increased 1.11 MPa, by 2.66%; and increased 0.06 MPa, by 0.54%, and for 45, 46, and 44 in the 30 µm infra-occlusion group, respectively. CONCLUSION: Within the limitation of this study, within 30 µm reduction of the occlusal surface height of implant-supported single crown, no significant difference of the peak values was observed.

Evaluation of Monomer-containing Isocyanate Groups on Stabilizing Demineralized Dentin Matrix Against Bond Interface Degradation.

PURPOSE: To evaluate the effect of urethane methacrylate precursor (UMP) on the enzymatic resistance of demineralized dentin (DD) matrices. MATERIALS AND METHODS: Experimental treatments containing 0 (control), 1, and 5 mmol/L UMP dissolved in an acetone (Ace) solution were formulated. Dentin matrix specimens were demineralized in vitro and immersed in the experimental treatments for 1 h. The treated specimens were then stored in 0.1 mg/mL collagenase solution for 24 h, after which their dry mass loss and hydroxyproline (HYP) release were assessed. The swelling ratios of specimens in each group were also evaluated. The interaction between UMP and the dentin matrix was observed using field-emission scanning electron microscopy (FE-SEM). Endogenous enzyme activity in dentin was evaluated using confocal laser scanning microscopy (CLSM). RESULTS: Compared with the other treatment groups, treatment with 1 mM and 5 mM UMP-Ace significantly decreased the dry mass loss, HYP release and swelling ratio of the DD matrix (p < 0.05). FE-SEM and CLSM observations showed that treatment with UMP-Ace protected the structure of the dentin matrix and decreased porosity within the dentin-collagen network. CONCLUSION: Treatment with 1 mM and 5 mM UMP-Ace protects DD matrix against collagenase degradation and may be clinically useful for improving the durability of the hybrid layer.

Zinc-doped bioactive glass-functionalized polyetheretherketone to enhance the biological response in bone regeneration.

Polyether ether ketone (PEEK) is gaining recognition as a highly promising polymer for orthopedic implants, attributed to its exceptional biocompatibility, ease of processing, and radiation resistance. However, its long-term in vivo application faces challenges, primarily due to suboptimal osseointegration from postimplantation inflammation and immune reactions. Consequently, biofunctionalization of PEEK implant surfaces emerges as a strategic approach to enhance osseointegration and increase the overall success rates of these implants. In our research, we engineered a multifaceted PEEK implant through the in situ integration of chitosan-coated zinc-doped bioactive glass nanoparticles (Zn-BGNs). This novel fabrication imbues the implant with immunomodulatory capabilities while bolstering its osseointegration potential. The biofunctionalized PEEK composite elicited several advantageous responses; it facilitated M2 macrophage polarization, curtailed the production of inflammatory mediators, and augmented the osteogenic differentiation of bone marrow mesenchymal stem cells. The experimental findings underscore the vital and intricate role of biofunctionalized PEEK implants in preserving normal bone immunity and metabolism. This study posits that utilizing chitosan-BGNs represents a direct and effective method for creating multifunctional implants. These implants are designed to facilitate biomineralization and immunomodulation, making them especially apt for orthopedic applications.

[Effect of circRASA2 targeting miR-543/TRAF6 axis on LPS-induced periodontal ligament cell proliferation and osteogenic differentiation].

PURPOSE: To investigate the possible role of circRASA2 in periodontitis and its potential regulatory mechanism. METHODS: Periodontitis cell model was established by lipopolysaccharide(LPS)-induced periodontal ligament cells(PDLCs). Cell proliferation activity was detected by CCK-8 assay, cell migration ability was detected by Transwell chamber assay, and the expression of osteogenic differentiation-related proteins in cells was detected by Western blot. The target miRNA of circRASA2 and its downstream target genes were predicted using the databases circinteractome and starBase, respectively, and the targeting relationship between the target genes was verified by dual-luciferase reporter gene experiment. GraphPad Prism 8.0 software package was used to analyze the data. RESULTS: circRASA2 was highly expressed in LPS-treated PDLCs cells. LPS-induced PDLCs cell proliferation activity, migration ability and osteogenic differentiation ability decreased, while knockdown of circRASA2 promoted proliferation, migration and osteogenic differentiation ability of PDLCs under LPS treatment. circRASA2 targeted and negatively regulated the expression of miR-543, and overexpression of miR-543 promoted proliferation, migration and osteogenic differentiation of PDLCs under LPS treatment. TRAF6 was a downstream target gene of miR-543, knockdown of circRASA2 down-regulated the expression of TRAF6 through the sponge action of miR-543. Overexpression of TRAF6 reversed the promotion of circRASA2 knockdown on proliferation, migration and osteogenic differentiation of PDLCs. CONCLUSIONS: circRASA2 accelerated the pathological process of periodontitis in vitro through miR-543/TRAF6 axis, and might improve periodontitis by targeting down the expression of circRASA2.

The histologic reaction and permanence of hyaluronic acid gel, calcium hydroxylapatite microspheres, and extracellular matrix bio gel.

BACKGROUND: The filling materials on the beauty market can be classified into three types: natural biological materials, synthetic polymer materials, and composites containing bioactive substances. However, comparative experimental data is lacking to compare their biological responses and permanence. AIMS: The main object of this study was to evaluate the biological response of these three types of fillers to provide a theoretical basis for clinical application. METHODS: Six-week-old female mice were injected subcutaneously with hyaluronic acid (HA) gel, calcium hydroxylapatite (CaHA) microspheres, and extracellular matrix (ECM) bio gel to observe the body reaction and permanence. At 1, 4, 8, and 16 weeks, the test sites were excised and analyzed by histopathology and proteomics. RESULTS: Extracellular matrix had a minimal foreign body response. HA had a good volume effect at the early stage but the volume retention rate was lower than CaHA in the long term. CaHA could stimulate neo-collagen formation. CONCLUSION: This study has proven the effectiveness and safety of these fillers and could provide clinical guidance for the plastic surgeon.

Mussel-inspired polymer with catechol and cationic Lys functionalities for dentin wet bonding.

Mussels can form tough and long-lasting adhesions to organic and inorganic surfaces in saline and impactive severe aquatic environments. Similar to mussel adhesion, dentin bonding occurs in a wet environment. However, unlike mussels, it is difficult to achieve long-lasting bonds with dentin. Moreover, water is considered a major hindrance in dentin bonding. Inspired by the synergistic effect of cationic lysine (Lys) and catechol on the elimination of the hydration layer during mussel adhesion, a catechol- and Lys-functionalized polymerizable polymer (catechol-Lys-methacrylate [CLM]) was synthesized to replicate the complex synergy between amino acids and catechol. The bond-promoting potential of 5 â€‹mg/mL CLM primer was confirmed using an in vitro wet dentin-bonding model, which was characterized by an improvement in bond strength and durability. CLM can adhere to wet demineralized dentin, with Lys acting as a molecular vanguard to expel water. Subsequently, a myriad of interfacial interactions can be obtained by introducing the catechol group into the interface. Additionally, tough and long-lasting adhesion, similar to that formed by mussels, can be achieved by grafting CLM onto type I collagen via covalent bonds, hydrogen bonds, Van der Waals interactions, and cation-π interactions, which can enhance the mechanical and chemical stability of collagen, increase the enzymatic resistance of collagen, and provide additional physical/chemical adhesion to dentin bonds. Catechol- and cationic Lys-functionalized polymers can improve the stability of the resin-dentin interface under wet conditions.

Enhancing bioactivity and stability of polymer-based material-tissue interface through coupling multiscale interfacial interactions with atomic-thin TiO2 nanosheets.

Stable and bioactive material-tissue interface (MTF) basically determines the clinical applications of biomaterials in wound healing, sustained drug release, and tissue engineering. Although many inorganic nanomaterials have been widely explored to enhance the stability and bioactivity of polymer-based biomaterials, most are still restricted by their stability and biocompatibility. Here we demonstrate the enhanced bioactivity and stability of polymer-matrix bio-composite through coupling multiscale material-tissue interfacial interactions with atomically thin TiO2 nanosheets. Resin modified with TiO2 nanosheets displays improved mechanical properties, hydrophilicity, and stability. Also, we confirm that this resin can effectively stimulate the adhesion, proliferation, and differentiation into osteogenic and odontogenic lineages of human dental pulp stem cells using in vitro cell-resin interface model. TiO2 nanosheets can also enhance the interaction between demineralized dentinal collagen and resin. Our results suggest an approach to effectively up-regulate the stability and bioactivity of MTFs by designing biocompatible materials at the sub-nanoscale. Electronic Supplementary Material: Supplementary material (further details of fabrication and characterization of TiO2 NSs and TiO2-ARCs, the bioactivity evaluation of TiO2-ARCs on hDPSCs, and the measurement of interaction with demineralized dentin collagen) is available in the online version of this article at 10.1007/s12274-022-5153-1.

Evaluation of a novel primer containing isocyanate group on dentin bonding durability.

OBJECTIVES: To evaluate the benefits of a novel dentin-bonding primer, namely, isocyanate-terminated urethane methacrylate precursor (UMP), which can form covalent bonds with demineralized dentin collagen. METHODS: The synthesized and purified UMP monomer was characterized and tested its effects on the degree of conversion (DC) and wettability of an acetone-based dental adhesive. Then UMP primers of different concentrations were formulated and used to prepare adhesive specimens, which were compared with solvent-treated groups. Primer-treated specimens with and without aging were also compared. To evaluate the bonding interface, microtensile strength tests, nano-indentation tests and nanoleakage- eavaluation were performed using a field-emission scanning electron microscope and nano-indenter. Data were analyzed using SPSS 20.0 software with significance set at α = 0.05 using one-way analysis of variance (ANOVA) and two-way ANOVA to characterize the effects of the primer. RESULTS: Treatment with the UMP primer promoted the DC and wettability of the adhesive on the demineralized dentin surface (P < 0.05); it also increased the bond strength of the aged dentin bonding interface (P < 0.05). Nanoleakage was reduced; the bonding interface became more stable, and the continuity and strength of the hybrid layer improved (P < 0.05) following UMP treatment. The application of 5 mM UMP as a primer for dentin bonding could lead to a stable bonding interface and long-lasting bonding effects. SIGNIFICANCE: The use of 5 mM UMP primer developed in this study could improve dentin bonding durability and has excellent clinical application prospects.

Facile fabrication of biodegradable endothelium-mimicking coatings on bioabsorbable zinc-alloy stents by one-step electrophoretic deposition.

The zinc-alloy stent is one of the best potential candidates for bioabsorbable metal stents because of its appropriate corrosion rate aligned to the duration of the healing process of the surrounding vessel tissues. However, excessive release of zinc ions, causing cytotoxicity of endothelial cells, and insufficient surface bio-functions of Zn-alloy stents lead to considerable challenge in their application. Herein, one-step electrophoretic deposition was employed to apply a hybrid coating of polycarbonate, tannic acid, and copper ions with tailored functions on Zn-alloy stents to enhance their corrosion resistance and provide an endothelium-mimicking surface. Specifically, the synthesized amino-functionalized aliphatic polycarbonates endowed the hybrid coating with specific surface-erosion properties, resulting in superior corrosion resistance and long-term stability in degradation tests both in vitro and in vivo. The immobilized copper ions enabled the catalytic generation of nitric oxide and promoted the adhesion and proliferation of endothelial cells on zinc alloy. The added tannic acid firmly chelated the copper ions and formed durable phenolic-copper-amine crosslinked networks by electrostatic interaction, resulting in long-term stability of the hybrid coating during the 21 day dynamic immersion test. Tannic acid exerted a synergistic antibacterial effect with copper ions as well as a reduction in the inflammatory response to the zinc substrate. In addition, the hybrid coating improved the in vitro hemocompatibility of zinc alloys. By adjusting the amount of chelated copper in the coating system, the biological function of the corresponding coatings can be controlled, providing a facile surface treatment strategy to promote the progress of zinc-alloy stents in clinical applications.

Oral and maxillofacial pain as the first sign of metastasis of an occult primary tumour: A fifteen-year retrospective study.

BACKGROUND: Metastatic adenocarcinoma of the jaw (MAJ) is a rare disease that accounts for 1%-3% of all oral and maxillofacial malignant tumours. Oral and maxillofacial pain may be the first symptom of metastatic spread of an occult primary tumour. Therefore, early identification of oral and maxillofacial pain by dental professionals is critical. AIM: To explore the clinical and computerized tomography (CT) features of MAJ with oral and maxillofacial pain as the first symptom. METHODS: The medical records of all patients who were treated in our hospital between January 2006 and February 2020, and diagnosed with MAJ with oral and maxillofacial pain as the first symptom, were reviewed retrospectively. Clinical data were collected on age, sex, medical history, clinical manifestations, site of metastasis, and site of the primary lesion. CT features were analysed in detail, and a radiological classification scheme comprising five types: Osteolytic, osteoblastic, mixed, cystic, and alveolar bone resorption was proposed. RESULTS: The primary sites of MAJ were the lungs (n = 6), liver (n = 4), kidneys (n = 2), prostate (n = 1), and gastric cardia (n = 1). Five tumours were classified as the osteolytic type, all with a permeative margin (100%, P < 0.05), and three were classified as the mixed type, mostly with a moth-eaten margin (80%, P < 0.05). The cystic (n = 3) and alveolar bone resorption (n = 1) types had geographic margins, and the osteoblastic type (n = 1) had sclerotic margins. Moreover, nine tumours showed periosteal reaction and five showed a localised soft tissue mass, while the occurrence of jaw expansion was relatively rare. CONCLUSION: MAJ has complex clinical and CT features. Oral and maxillofacial pain may be the first sign of a primary tumour affecting other sites.

Aquabots.

Soft robots, made from elastomers, easily bend and flex, but deformability constraints severely limit navigation through and within narrow, confined spaces. Using aqueous two-phase systems we print water-in-water constructs that, by aqueous phase-separation-induced self-assembly, produce ultrasoft liquid robots, termed aquabots, comprised of hierarchical structures that span in length scale from the nanoscopic to microsciopic, that are beyond the resolution limits of printing and overcome the deformability barrier. The exterior of the compartmentalized membranes is easily functionalized, for example, by binding enzymes, catalytic nanoparticles, and magnetic nanoparticles that impart sensitive magnetic responsiveness. These ultrasoft aquabots can adapt their shape for gripping and transporting objects and can be used for targeted photocatalysis, delivery, and release in confined and tortuous spaces. These biocompatible, multicompartmental, and multifunctional aquabots can be readily applied to medical micromanipulation, targeted cargo delivery, tissue engineering, and biomimetics.

Co-doping optimized hydrogel-elastomer micro-actuators for versatile biomimetic motions.

Hydrogels can respond to changes in humidity or temperature, while elastomers can resist structural collapse due to dehydration or external force application. A hybrid bilayer of hydrogel-elastomers while retaining the merits of both the hydrogels and elastomers has emerged as a promising stimuli-responsive micro-actuator. However, the preparation of a hydrogel-elastomer micro-actuator requires multiple steps, mainly due to the differences in the surface properties of these two materials. Among them, the steps to surface-treat the elastomer and functionalize the material of each layer involve intricate processes and excessive consumption of resources. In this work, we introduce a co-doping method to optimize the preparation of a stimuli-responsive hydrogel-elastomer micro-actuator. The surface treatment and functionalization processes are combined into one step by directly doping the polymerization initiator and functional nanomaterials into the hybrid bilayer. The thermo-responsive hydrogel is combined with a photothermal elastomer to fabricate a soft micro-actuator that can bend and unbend in response to changes in humidity and light. Based on this actuator, a set of biomimetic soft micro-robots were developed, demonstrating a series of motions, such as grabbing, crawling, and jumping. This strategy of stimuli-responsive micro-actuator preparation can benefit the hydrogel-elastomer hybrid micro-robot designs for applications ranging from self-locomotive robots in environmental monitoring to drug delivery in biomedical engineering.

Single-Shot Smartphone-Based Quantitative Phase Imaging Using a Distorted Grating.

Blood testing has been used as an essential tool to diagnose diseases for decades. Recently, there has been a rapid developing trend in using Quantitative Phase Imaging (QPI) methods for blood cell screening. Compared to traditional blood testing techniques, QPI has the advantage of avoiding dyeing or staining the specimen, which may cause damage to the cells. However, most existing systems are bulky and costly, requiring experienced personnel to operate. This work demonstrates the integration of one QPI method onto a smartphone platform and the application of imaging red blood cells. The adopted QPI method is based on solving the Intensity Transport Equation (ITE) from two de-focused pupil images taken in one shot by the smartphone camera. The device demonstrates a system resolution of about 1 µm, and is ready to be used for 3D morphological study of red blood cells.