A digital approach to fabricating a custom holder for the attachment of a mandibular sensor of an optical jaw motion tracking system: A dental technique.

A digital approach to fabricating a custom holder to attach a mandibular sensor of an optical jaw motion tracking system is described. Typically, jaw motion tracking systems come with standard holders. However, additional chairside time is still required to adapt the holder's arm to the individual arch and securely attach the holder to the mandibular teeth. Moreover, the placement of the standard holder is problematic in patients with a deep vertical overlap or with short clinical crowns. This technique offers a digital approach to designing and fabricating a custom holder in situations where standard holders cannot be efficiently attached. The custom holder is designed to accommodate the available space without interfering with the occlusion, thereby minimizing the time needed to attach the holder and optimizing the workflow for clinical jaw motion tracking.

Superimposing digital arch scans onto cone beam computed tomography scans with metallic artifacts by applying a radiopaque occlusal registration material: A chairside dental technique.

Precise alignment between digital arch scans and cone beam computed tomography (CBCT) scans is a crucial step in computer-aided implant planning and placement. However, clinicians frequently encounter challenges during this process when imaging patients with existing metal restorations or orthodontic devices, as these can introduce metallic artifacts on CBCT scans that lead to alignment deviations. The presented technique describes a straightforward approach using a radiopaque occlusal registration material as a radiographic marker to facilitate the alignment between digital arch scans and CBCT scans with metallic artifacts. This technique simplifies the clinical workflow by eliminating the need for additional radiographic templates or specialized devices, offering a cost-effective option for clinicians.

Digital cross-mounting of intraoral scan casts from a virtual articulator to a mechanical articulator by using a custom transfer plate: A dental technique.

With the development of digital dental technologies, a complete digital workflow without using physical casts has become possible. However, for certain clinical and dental laboratory procedures, especially in complex rehabilitation treatments, physically mounted casts in an ideal location in a mechanical articulator are still necessary for treatment planning and restoration fabrication. This technique report describes a digital approach to fabricating a custom transfer plate to cross mount intraoral scan casts from a virtual articulator to the corresponding mechanical articulator. This technique eliminates the need for conventional physical facebow transfer processes and offers a straightforward approach to integrating virtual procedures with analog workflows.

Intraoral scanner-based virtual facebow transferring: A chairside dental technique.

Accurately mounting dental casts on an articulator is an essential step in prosthetic treatments. In digital dentistry, virtual articulator mounting procedures rely on virtual facebow records. However, virtual facebow records usually require devices like face scanners or jaw motion tracking systems that are not commonly available in most dental practices. The present technique report describes a straightforward intraoral scanner-based virtual facebow transfer approach. In this technique, a reference facebow joint support was first scanned and aligned with a virtual articulator. Then, a patient's facebow joint support and bite fork assembly were scanned chairside with an intraoral scanner and aligned with the virtual articulator by matching common features with the reference facebow joint support. After aligning the patient's intraoral scans with the patient's bite fork scan that was already superimposed on the virtual articulator, a virtual mounting process was achieved. Once the corresponding reference facebow joint supports have been generated, this technique can be easily implemented with most facebow systems and be seamlessly integrated into daily clinical practice as only an intraoral scanner and a conventional facebow were required.

A cast-free approach to fabricating an implant-supported interim restoration: A dental technique.

A cast-free approach is described to fabricate an implant-supported interim restoration by using the postoperative cone beam computed tomography (CBCT) scan to locate the placed implant. A postoperative intraoral scan was aligned to the postoperative CBCT scan through a dental implant planning software program. An attached interim abutment and implant analog complex was then scanned and superimposed on the placed implant in the postoperative CBCT scan. Once the best alignment was achieved, a virtual cast was generated, and an interim restoration with bilateral positioning wings was fabricated on the interim abutment and inserted during the second-stage surgery. This technique offers a cast-free approach to inserting an implant-supported interim restoration immediately after the second-stage surgery to guide the healing of the soft tissue that can minimize chairside time and optimize the clinical workflow.

GSH-Activatable Aggregation-Induced Emission Cationic Lipid for Efficient Gene Delivery.

The key to gene therapy is the design of biocompatible and efficient delivery systems. In this work, a glutathione (GSH)-activated aggregation-induced-emission (AIE) cationic amphiphilic lipid, termed QM-SS-KK, was prepared for nonviral gene delivery. QM-SS-KK was composed of a hydrophilic biocompatible lysine tripeptide headgroup, a GSH-triggered disulfide linkage, and a hydrophobic AIE fluorophore QM-OH (QM: quinoline-malononitrile) tail. The peptide moiety could not only efficiently compact DNA but also well modulate the dispersion properties of QM-SS-KK, leading to the fluorescence-off state before GSH treatment. The cleavage of disulfide in QM-SS-KK by GSH generated AIE signals in situ with a tracking ability. The liposomes consisted of QM-SS-KK, and 1,2-dioleoylphosphatidylethanolamine (DOPE) (QM-SS-KK/DOPE) delivered plasmid DNAs (pDNAs) into cells with high efficiency. In particular, QM-SS-KK/DOPE had an enhanced transfection efficiency (TE) in the presence of 10% serum, which was two times higher than that of the commercial transfection agent PEI25K. These results highlighted the great potential of peptide and QM-based fluorescence AIE lipids for gene delivery applications.

A digital approach to create a virtual implant preliminary cast for the fabrication of a splinted framework and custom open tray for multiple implants impression making: A dental technique.

A digital approach is described for fabricating a splinted framework and custom open tray for the impression of multiple implants based on a virtually created implant cast with the digital prediction of the future impression coping positions. In this technique, impression copings to be used in the definitive impression-making process were digitally scanned and aligned to a preliminary cast using installed protective caps of screw-retained abutments as references, which resulted in a virtual cast that offers information both about the impression coping positions and their surrounding tissues and could allow a splinted framework and custom open tray to be digitally designed and fabricated. Creation of a virtual cast through digital technologies eliminates the traditional manual splinted framework and custom tray fabrication procedures. Additionally, only one set of impression copings and analogs is needed in this technique, thereby reducing treatment time and cost. It also offers a splinted framework and custom open tray with consistent quality.

An Indirect Digital Technique to Transfer 3D Printed Casts to a Mechanical Articulator With Individual Sagittal Condylar Inclination Settings Using CBCT and Intraoral Scans.

With the widespread application of digital impression techniques in prosthetic dentistry, accurate intraoral scan mounting, and virtual articulator parameters setting as per patients' anatomic structures are essential for treatment planning and restoration fabrication, especially for complex rehabilitation cases; meanwhile, marginal fit checking, occlusal adjustment, and porcelain layering of restorations are also crucial procedures in all cases in which the analog procedure to mount maxillary arches on a mechanical articulator is still required. This technique article presents an indirect digital approach that can first achieve virtual intraoral scan mounting and sagittal condylar inclination value setting of an Artex virtual articulator based on bony structures provided by a single cone beam computed tomography scan. It then facilitates the transfer of virtually mounted intraoral scans from the virtual articulator to the matched Artex mechanical articulator by relating a digitally scanned mounting plate of the Artex mechanical articulator to the virtual articulator, printing the intraoral scan and mounting plate scan assembly, and then mounting the printed casts on the mechanical articulator based on the printed mounting plate. This technique eliminates the conventional facebow transfer and protrusive bite registration procedures and offers a straightforward approach for the seamless integration of virtual environments and analog workflows into clinical practice. It aids in the design of restorations that are harmonious with the mandibular movements and reduces chairside adjustment time.

A Novel Technique to Align the Intraoral Scans to the Virtual Articulator and Set the Patient-Specific Sagittal Condylar Inclination.

Customized cast orientations and parameter settings of the virtual articulator according to the patient's condyles are indispensable parts of today's digital workflows in prosthodontics. This article describes a digital technique to align the intraoral scans to a virtual articulator by using a facial scanner to locate the patient's cutaneous landmarks of the arbitrary hinge axis and the reference plane, and to customize the sagittal condylar inclination of the virtual articulator through a digital protrusive interocclusal record and a dental computer-aided design software program. It enables individual cast orientations and virtual articulator parameter settings without conventional facebow transferring and bite registration procedures and can be easily integrated with most virtual articulator systems on the market to allow clinicians and technicians to work in a complete digital workflow and facilitate customized treatment planning and dental prosthesis fabrication.

[Effects of Three Illuminants on the Color of High Translucent Multilayered Zirconia].

OBJECTIVE: To evaluate the effects of three common illuminants on the color of four brands of high translucent multilayered zirconia (HTMZ) ceramics so as to provide reference for clinical practice and dental restoration fabrication, and to reduce the risks for illuminant change causing color mismatch between the natural teeth and the restorations made of HTMZ. METHODS: Four brands of commonly used HTMZ were selected and ten cuboid samples ( n=10/group) of 12 mm×10 mm×0.8 mm were prepared for each type of HTMZ. The L*, a*, and b* values of the samples were measured under D65, A and F2, three standard illuminants. Then, the L*, a*, and b* values were statistically analyzed by using factors of the type of the illuminant and the brand of the zirconia. Color difference (ΔE) of samples of the same brand under exposure to changed illuminants was also calculated. RESULTS: When the same samples were exposure to different illuminants, there was no significant difference in the L* value, the a* value for the different iluminants was shown to be illuminant A>illuminant F2>illuminant D65, and the b* value was shown to be illuminant F2>illuminant D65>illuminant A. The L*, a*, and b* values of samples of different brands showed statistically significant difference when they were exposed to the same illuminant ( P<0.0001). Samples of the same brand showed ΔE when they were under the three different illuninants, and all ΔE were clinically acceptable. CONCLUSION: The types of illuminant used, to a certain degree, affected the hue and chroma of HTMZ. There were colorimetric differences between restorations made of different brands of HTMZ ceramics of the same color. The types of illuminants most common to the daily life of patients and the color characteristics of materials of different brands should be taken into consideration to facilitate the selection of restoration materials and dental restoration fabrication, and to reduce the risks for color mismatch between the restorations and the adjacent teeth caused by the change of illuminants.

Adsorptive decontamination of Cu2+-contaminated water and soil by carboxylated graphene oxide/chitosan/cellulose composite beads.

Graphene adsorbents have been applied to remove diverse pollutants from aqueous systems. However, the mechanical strength of most graphene adsorbents is low and the fragile graphene sheets are released into the environment. In this study, we prepared carboxylated graphene oxide/chitosan/cellulose (GCCSC) composite beads with good mechanical strength for the immobilization of Cu2+ from both water and soil. The proportional limit of GCCSC beads was 3.2 N, a much larger value than graphene oxide beads (0.2 N). The largest pressure for GCCSC beads recorded before brittle failure was 26 N. The Cu2+ adsorption capacity of GCCSC beads was 22.4 mg/g in aqueous systems at initial Cu2+ concentration of 40 µg/mL, which is competitive with many efficient adsorbents. The partition coefficient (PC) for the Cu2+ adsorption onto GCCSC beads was 1.12 mg/g/µM at Ce of 0.83 mg/L and qe of 14.3 mg/g. The PC decreased to 0.055 mg/g/µM at Ce of 26.0 mg/L and qe of 22.4 mg/g. The adsorption kinetics of Cu2+ on GCCSC beads were moderately fast and required approximately 3 h to reach equilibrium with a k2 of 0.0021 g/(mg·min). A lower temperature and higher pH slightly increased the adsorption capacity of GCCSC beads. The ionic strength did not influence the adsorption. The porous structure of GCCSC beads blocked the direct contact between soil and the graphene surface; thus, a high Cu2+ immobilization efficiency was achieved by GCCSC beads applied to soil. The implications for the design of high-performance graphene adsorbents for water and soil remediation are discussed.

Evaluation of the accuracy of a fully digital method of measuring sagittal condylar inclination.

OBJECTIVES: This clinical study aimed to evaluate the accuracy of a fully digital technique for measuring sagittal condylar inclination (SCI), as well as validating whether differences existed between the left and right SCI values of the same participant, to provide a reference for clinical practice. METHODS: Ten participants with good occlusal relationship and normal temporomandibular joint were recruited. Three methods were used to measure the SCI values of the participants, namely, A (mechanical facebow transferring and mechanical articulator-based measuring method with physical protrusive interocclusal registration), B (face scan-based virtual facebow and virtual articulator-based measuring method with digital protrusive interocclusal registration), and C (jaw motion tracking system-based measuring method). With the group subjected to methods A and C as the control, the SCI values obtained by the three methods were statistically analyzed. The left and right SCI values of the same participant were also compared. RESULTS: The left and right SCI values measured by method A were 41.70°±7.09° and 42.80°±8.62°, those by method B were 35.09°±12.49° and 37.63°±12.10°, and those by method C were 39.43°±8.72° and 38.45°±6.91°. No significant difference existed among the SCI values measured by the three methods (P>0.05). Meanwhile, no statistical difference existed between the SCI values on the left and right sides of the same participant (P>0.05). CONCLUSIONS: The accuracy of the virtual facebow and digital protrusive occlusal registration based SCI measuring method was the same as that of mechanical facebow based and jaw motion tracking system-based methods. The SCI values on the left and right sides of the same participant were similar. Clinically, an appropriate SCI measurement and setting strategy can be selected based on the actual situations.

Trueness evaluation of three intraoral scanners for the recording of maximal intercuspal position.

OBJECTIVES: This clinical study aimed to assess the trueness of three intraoral scanners for the recor-ding of the maximal intercuspal position (MIP) to provide a reference for clinical practice. METHODS: Ten participants with good occlusal relationship and healthy temporomandibular joint were recruited. For the control group, facebow transferring procedures were performed, and bite registrations at the MIP were used to transfer maxillary and mandibular casts to a mechanical articulator, which were then scanned with a laboratory scanner to obtain digital cast data. For the experimental groups, three intraoral scanners (Trios 3, Carestream 3600, and Aoralscan 3) were used to obtain digital casts of the participants at the MIP following the scanning workflows endorsed by the corresponding manufacturers. Subsequently, measurement points were marked on the control group's digital casts at the central incisors, canines, and first molars, and corresponding distances between these points on the maxillary and mandibular casts were measured to calculate the sum of measured distances (DA). Distances between measurement points in the incisor (DI), canine (DC), and first molar (DM) regions were also calculated. The control group's maxillary and mandibular digital casts with the added measurement points were aligned with the experimental group's casts, and DA, DI, DC, and DM values of the aligned control casts were determined. Statistical analysis was performed on DA, DI, DC, and DM obtained from both the control and experimental groups to evaluate the trueness of the three intraoral scanners for the recording of MIP. RESULTS: In the control group, DA, DI, DC, and DM values were (39.58±6.40), (13.64±3.58), (14.91±2.85), and (11.03±1.56) mm. The Trios 3 group had values of (38.99±6.60), (13.42±3.66), (14.55±2.87), and (11.03±1.69) mm. The Carestream 3600 group showed values of (38.57±6.36), (13.56±3.68), (14.45±2.85), and (10.55±1.41) mm, while the Aoralscan 3 group had values of (38.16±5.69), (13.03±3.54), (14.23±2.59), and (10.90±1.54) mm. Analysis of variance revealed no statistically significant differences between the experimental and control groups for overall deviation DA (P=0.96), as well as local deviations DI (P=0.98), DC (P=0.96), and DM (P=0.89). CONCLUSIONS: With standardized scanning protocols, the three intraoral scanners demonstrated comparable trueness to traditional methods in recording MIP, fulfilling clinical requirements.

Calibrated intraoral scan protocol (CISP) for full-arch implant impressions: An in vitro comparison to conventional impression, intraoral scan, and intraoral scan with scan-aid.

OBJECTIVE: To assess a newly developed intraoral scan protocol in enhancing the accuracy of complete-arch implant impressions. MATERIALS AND METHODS: Four impression approaches were applied to the same maxillary edentulous model with 6 implants: (1) intraoral scan (IOS), (2) intraoral scan with scan aid (IOS-SA), (3) calibrated intraoral scan protocol (CISP), and (4) conventional splinted open-tray impression (CONV). Each approach was repeated 10 times, and a direct scan of the model with a desktop scanner was used as a reference model. The alignment of scans and the reference model was conducted by two methods: (a) aligning all scan bodies to evaluate the overall fit, and (b) aligning the first and second scan bodies to simulate the Sheffield fit test for passive fitting of multiple implant-supported prostheses. Linear deviations from the reference model (trueness) and within each group (precision) were analyzed using Python scripts. RESULTS: When aligned by all scan bodies, the CISP group exhibited comparable mean trueness (38.33 µm) and precision (45.97 µm) to the CONV group (44.30 and 47.92 µm respectively), both of which significantly outperformed the IOS group (86.82 and 83.17 µm, respectively). Furthermore, in the virtual Sheffield fit test, the CISP group achieved the highest levels of mean trueness at the end span (121.7 µm), making a linear deviation reduction of 36.7%, 60%, and 41.4% when compared to the CONV, the IOS, and the IOS-SA groups, respectively. Moreover, the CISP group (104.3 µm) displayed a remarkable 65, 182, and 86 µm advantage in precision over the CONV, IOS, and IOS-SA groups, respectively. CONCLUSION: CISP demonstrated comparable accuracy to the gold standard, the conventional splinted open-tray impression. Furthermore, it excelled in the virtual passive fitting test.

Evaluation of the accuracy of implant placement by using implant positional guide versus freehand: a prospective clinical study.

PURPOSE: The aim of this study is to examine and compare the accuracy of implant placement using implant positional guide and freehand. METHODS: 48 implants were placed in patients with single tooth loss with implant positional guide and freehand, respectively. The accuracy of implant placement was assessed by comparing the actual and planned position, including four parameters: coronal deviation, apical deviation, angular deviation, and vertical deviation. RESULTS: Comparing all the variables, it has been found that the implant positional guide is more accurate than the freehand. All parameters describing in the deviation were significantly lower in the implant positional guide group than the freehand. CONCLUSIONS: The implant positional guide can act as a practicable tool for dental implant surgery. It is a promising technology that guarantees low cost and high precision in implant surgery. However, based on the restricted evidence from clinical studies, longer follow-up periods, larger population studies, and standardized experimental studies are required. Trial registration CHICTR, ChiCTR2300071024. Registered 28 April 2023-CHICTR, ChiCTR2300071024. Registered 28 April 2023-Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=195424 .

Toxicity and activity inhibition of metal-organic framework MOF-199 to nitrogen-fixing bacterium Azotobacter vinelandii.

Metal-organic framework (MOF) materials with fantastic properties have found important applications in various areas. Learning the lessons from plastics and microplastics, it is urgent to investigate the environmental impacts of emerging materials to avoid potential pollution. However, the environmental toxicity and risks of MOF materials are seldom reported. Herein, we studied the toxicity and activity inhibition of MOF-199 to nitrogen-fixing bacterium Azotobacter vinelandii. MOF-199 significantly suppressed the growth of A. vinelandii and led to cell death at 40 mg/L. MOF-199 penetrated the cell wall and induced the shrinking of bacterial cells. MOF-199 reduced the nitrogen fixation activity of A. vinelandii at 40 mg/L by decreasing the gene nifH levels and inhibiting the Ca2+Mg2+-ATPase activity, which was further confirmed by the changes in oxidative phosphorylation related genes. Complete growth inhibition and activity loss of A. vinelandii occurred at 60 mg/L of MOF-199. The toxicological mechanism of MOF-199 to A. vinelandii was assigned to the oxidative stress, which occurred at 20 mg/L and higher. Both Cu2+ release and particulates themselves contributed to the toxicity of MOF-199 to A. vinelandii. These findings highlighted the environmental hazards and risks of MOF materials to nitrogen-fixing bacteria and nitrogen fixation in the biogeochemical cycle.

Biodefunctionalization of functionalized single-walled carbon nanotubes in mice.

Chemically modified carbon nanotubes with hydrophilic functionalities such as polyethylene glycols (PEGs) are widely pursued for potential biological and biomedical applications. In this study, PEGylated single-walled carbon nanotubes (PEG-SWNT) were intravenously administrated into mice to study their biodefunctionalization in vivo by using complementary Raman and photoluminescence measurements. There was meaningful defunctionalization of PEG-SWNT in liver over time, but not in spleen under similar conditions. The evidence from spectroscopic characterization and analyses is presented, and mechanistic implications are discussed.

Harnessing Phosphato-Platinum Bonding Induced Supramolecular Assembly for Systemic Cisplatin Delivery.

To improve the therapeutic index of cisplatin (CDDP), we present here a new paradigm of drug-induced self-assembly by harnessing phosphato-platinum complexation. Specifically, we show that a phosphato-platinum cross-linked micelle (PpY/Pt) can be generated by using a block copolymer methoxy-poly(ethylene glycol)-block-poly(l-phosphotyrosine) (mPEG-b-PpY). Coating of PpY/Pt with a R9-iRGD peptide by simple mixing affords a targeting micelle with near neutral-charged surface (iPpY/Pt). The micelles feature in well-controlled sizes below 50 nm and high stability under physiological conditions, and can withstand various environmental stresses. Importantly, the micelles demonstrate on-demand drug release profiles in response to pathological cues such as high ATP concentration and acidic pH. In vitro, the micelles are efficiently internalized and almost equally potent compared to CDDP. Moreover, iPpY/Pt induce greater cytotoxicity than PpY/Pt in a 3D tumor spheroid model likely due to its deeper tumor penetration. In vivo, the micelles exhibit prolonged circulation half-lives, enhanced tumor accumulation, excellent tumor growth inhibition in a xenograft HeLa model and an orthotropic mammary 4T1 model, and improved safety profiles evidenced by the reduced nephrotoxicity. Together, this work demonstrates for the first time that phosphato-platinum complexation can be exploited for effective delivery of CDDP, and suggests a paradigm shift of constructing nanosystems for other anticancer metallodrugs.

Blood Clearance, Distribution, Transformation, Excretion, and Toxicity of Near-Infrared Quantum Dots Ag2Se in Mice.

As a novel fluorescent probe in the second near-infrared window, Ag2Se quantum dots (QDs) exhibit great prospect in in vivo imaging due to their maximal penetration depth and negligible background. However, the in vivo behavior and toxicity of Ag2Se QDs still largely remain unknown, which severely hinders their wide-ranging biomedical applications. Herein, we systematically studied the blood clearance, distribution, transformation, excretion, and toxicity of polyethylene glycol (PEG) coated Ag2Se QDs in mice after intravenous administration with a high dose of 8 µmol/kg body weight. QDs are quickly cleared from the blood with a circulation half-life of 0.4 h. QDs mainly accumulate in liver and spleen and are remarkably transformed into Ag and Se within 1 week. Ag is excreted from the body readily through both feces and urine, whereas Se is excreted hardly. The toxicological evaluations demonstrate that there is no overt acute toxicity of Ag2Se QDs to mice. Moreover, in regard to the in vivo stability problem of Ag2Se QDs, the biotransformation and its related metabolism are intensively discussed, and some promising coating means for Ag2Se QDs to avert transformation are proposed as well. Our work lays a solid foundation for safe applications of Ag2Se QDs in bioimaging in the future.