Digital fabrication of a maxillary obturator prosthesis by using a 3-dimensionally-printed polyetheretherketone framework.

The digital fabrication of a maxillary obturator with a 3D-printed polyetheretherketone (PEEK) framework is described. Digital oral data were scanned for the computer-aided design (CAD) of the framework and the 3D printing of a preliminary resin cast. The framework was accurately printed from a PEEK filament material. A secondary impression was made to fabricate the definitive cast. The PEEK framework exhibited precise fit, excellent retention, and reduced weight compared with a typical metal framework.

Polyetherketoneketone, a high-performance polymer for splinting mobile teeth: A clinical report.

A digital workflow for fabricating a polyetherketoneketone (PEKK) periodontal splint is described. The antibacterial properties of PEKK and the precision and efficiency of digital technology led to the provision of a splint with no adverse effects on oral hygiene or periodontal maintenance during a 2-year follow-up.

Influence of intraoral scanning duration on data accuracy.

STATEMENT OF PROBLEM: The use of intraoral scanners (IOSs) correlates with clinical outcome and patient satisfaction. While the accuracy of IOSs has been well evaluated, studies on the effect of scanning duration on data accuracy are limited. PURPOSE: The purpose of this in vitro study was to investigate the relationship between different scanning durations and the accuracy of the scanned data. MATERIAL AND METHODS: Two experienced operators used the same intraoral scanner (TRIOS 3; 3Shape A/S) to scan a gypsum cast, but with 5 different scanning durations (30 seconds, 60 seconds, 90 seconds, 120 seconds, and 180 seconds), and the trueness of the scanned data was assessed. Ten scans for each duration group were performed, and all the acquired data were evaluated for precision analysis. In addition, each scanned complete arch cast was divided into anterior and posterior regions at the canine teeth, and the 3-way ANOVA test was used to assess the scanning trueness and precision of the scanned anterior and posterior dental arch. RESULTS: The intraoral scanning results between the 2 operators were highly consistent. The data of the 30-second group showed the lowest trueness and precision (P<.001), whereas no significant difference was found among the other groups (P>.05). The trueness and precision of the scanning data in the posterior region was inferior to that in the anterior region (P<.001). CONCLUSIONS: The duration time of the intraoral scanning (ranging from 60 seconds to 180 seconds) did not influence the accuracy of the acquired data, while excessively rapid scanning adversely affected accuracy.

Digital fabrication of an adult speech aid prosthesis by using a 3-dimensionally printed polyetheretherketone framework.

This article presents a digital fabrication method for a speech aid prosthesis by using a 3D-printed polyetheretherketone (PEEK) framework. The computer-aided design (CAD) of the speech aid prosthesis framework was based on oral scan data. The framework was printed with PEEK filament material supplemented with nanoTiO2 powder by fused deposition modeling (FDM). A resin preliminary cast was 3D printed, and an altered cast technique was adopted to fabricate the definitive cast. The PEEK framework exhibited precise fit, toothlike color, excellent mechanical properties, and reduced weight as compared with a typical metal framework. This technique describes the successful clinical application of 3D-printed PEEK material for the fabrication of an adult speech aid prosthesis.

Complete denture fabrication with polyetherketoneketone as a framework material: A clinical report.

This clinical report describes the fabrication of conventional complete dentures with polyetherketoneketone (PEKK) frameworks made with computer-aided design and computer-aided manufacturing (CAD-CAM). No biologic or prosthetic complications were observed at the 1-year follow-up.

Effects of surface treatments on the bonding properties of polyetherketoneketone to dentin: An in vitro study.

STATEMENT OF PROBLEM: Polyetherketoneketone (PEKK) has been recently introduced as a dental material for fixed dental prostheses. However, how surface treatments affect the bonding of PEKK to dentin is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effects of airborne-particle abrasion and acid etching on the bonding of PEKK to dentin. MATERIAL AND METHODS: Eighty-four PEKK specimens were fabricated, polished, and divided into 6 groups (n=14): no treatment (group NT), airborne-particle abrasion with 110-µm alumina particles (group Al), 98% sulfuric acid etching for 5 seconds (group SA5), 98% sulfuric acid etching for 30 seconds (group SA30), 98% sulfuric acid etching for 60 seconds (group SA60), and airborne-particle abrasion plus 98% sulfuric acid for 5 seconds (group AlSA5). Sixty PEKK specimens (n=10) were fabricated for the shear bond test. Another 24 PEKK specimens (n=4) were fabricated for surface element analysis and morphological observations. For each group, 2 specimens after surface treatments were randomly selected to examine scanning electron microscope (SEM) observations and surface element analysis. Another 2 specimens after bonding were randomly selected to examine cross-sectional observations. Airborne-particle abrasion with 110-µm alumina particles was performed to cobalt-chromium (Co-Cr) specimens (group Co-Cr, n=10). A light-polymerizing polymethylmethacrylate and composite resin primer (visio.link) was applied to the treated PEKK specimens and bonded with a resin cement (RelyX Ultimate) to dentin. The Co-Cr specimens were bonded with the resin cement to dentin. The shear bond strengths of all groups were tested by using a universal testing machine, and fracture analysis was performed. A statistical analysis was performed by using 1-way ANOVA, followed by the Student-Newman-Keuls-q post hoc test (α=.05). RESULTS: The shear bond strengths of groups SA5 and AlSA5 were higher than those of groups NT, Al, SA30, SA60, and Co-Cr (P＜.05). Group SA5 achieved the highest shear bond strength (16.84 ±1.84 MPa). The SEM observations showed that after surface treatments, groups SA5 and AlSA5 had a uniform sponge shape with small pores, while groups SA30 and SA60 had a collapsed shape with large pits and pores. The sulfur element content and H2SO4-etched thicknesses of groups SA30 and SA60 were higher than those of groups SA5 and AlSA5. The cross-sectional SEM observations of groups SA30 and SA60 after bonding revealed that H2SO4-etched pores were deeper and not filled with the bonding material. CONCLUSIONS: Compared with airborne-particle abrasion, the 98% sulfuric acid etching significantly improved the shear bond strength of PEKK to dentin. The surface treatment of 98% sulfuric acid etching for 5 seconds led to the high bond strength of PEKK to dentin, which meets the requirements for clinical use.

Effects of 3 kinds of processing techniques on the fitness of metal clasp. / 3ç§åŠ å·¥å·¥è‰ºå¯¹é‡‘å±žå¡çŽ¯å¯†åˆæ€§çš„å½±å“.

OBJECTIVES: At present, removable partial denture is still one of the main restoration methods for dentition defects. However, the trend for digital partial denture is becoming more and more obvious in the field of oral repair. However, there are relatively few studies on digital removable partial denture. The aim of this study is to investigate the effects of 3 processing technologies (precision casting, digital cutting, and 3D printing) on the fitness for the clasps of cobalt chromium alloy and pure titanium removable partial denture, and to provide a theoretical basis for the clinical application of digital removable partial denture. METHODS: Clasps of Co-Cr alloy and pure titanium were produced by 3 different processing technologies (precision casting, digital cutting, and 3D printing). There are 6 groups, including a casting pure titanium group, a casting cobalt chromium group, a cutting pure titanium group, a cutting cobalt chromium group, a printing pure titanium group, and a printing cobalt chromium group (n=6 per group). The gaps between the initial, middle, and tip of the lingual opposing arm of the clasp and the abutment were measured by fluorescent microscope, and the average value was taken as the index to measure the fitness between the clasp and the abutment. The fitness difference in three-arm clasp made of cobalt chromium alloy and pure titanium materials under 3 different technologies was compared. RESULTS: There was no statistical difference in fitness between the casting pure titanium group and the casting cobalt chromium group (P>0.05); there was no statistical difference in fitness between the cutting pure titanium group and the cutting cobalt chromium group (P>0.05); there was no statistical difference in fitness between the printing pure titanium group and the printing cobalt chromium group (P>0.05). When pure titanium was used, the fitness of the printing pure titanium group was the best (both P<0.05). There was no significant difference between the casting pure titanium group and the cutting pure titanium group (P>0.05). When cobalt chromium alloy was used, there was no significant difference in fitness among the 3 groups (P>0.05). CONCLUSIONS: The cobalt chromium alloy and pure titanium clasps made by precision casting, digital cutting, and 3D printing have good fitness. Under the same process, there is no significant difference between cobalt chromium alloy and pure titanium clasps. The 3D printing pure titanium clasps have better fitness than casting pure titanium and cutting pure titanium clasps, which meet the needs of clinical application.

A digital guiding device to facilitate cementation of porcelain laminate veneers.

This article presents a computer-aided design and computer-aided manufacturing (CAD-CAM) guiding device to facilitate the simultaneous preconditioning and cementation of multiunit porcelain laminate veneers (PLVs). The guiding device was designed from the digital cast of the PLVs and definitive cast assembly, with gingival margins 2 mm from the PLV margins and lingual perforations and milled from a transparent polymethyl methacrylate (PMMA) disk. The PLVs were seated in the guiding device during the preconditioning procedures and transferred to the abutment teeth with luting cement loaded on the intaglio surfaces. Excess resin cement was removed while the guiding device held the PLVs in place. This technique provides predictable, accurate, and efficient simultaneous preconditioning and cementing of PLVs.

A speech bulb prosthesis for a soft palate defect with a polyetherketoneketone (PEKK) framework fabricated by multiple digital techniques: A clinical report.

This clinical report described a digital workflow for the design, manufacture, and clinical delivery of a polyetherketoneketone (PEKK) removable dental prosthesis with a speech bulb. The process combined intraoral scanning, digital milling for the PEKK framework, and 3D printing for the definitive cast.

circRNA CDR1as Regulated the Proliferation of Human Periodontal Ligament Stem Cells under a Lipopolysaccharide-Induced Inflammatory Condition.

circRNA CDR1as (CDR1as) has been demonstrated to play important roles in a variety of inflammation-related diseases by acting as miRNA sponges. The present study is aimed at investigating the potential roles of CDR1as in the proliferation of human periodontal ligament stem cells (PDLSCs) under an inflammatory condition induced by Porphyromonas gingivalis-derived lipopolysaccharide (LPS). Human periodontal ligament cells (PDLCs) were isolated from periodontal ligament tissue, and PDLSCs were sorted from PDLCs based on the STRO-1 expression through fluorescence-activated cell sorting. We further found that CDR1as was significantly downregulated in LPS-treated PDLSCs compared to untreated cells, as well as in normal periodontal ligament tissues compared to periodontitis tissues. Knockdown of CDR1as promoted LPS-induced proliferative inhibition of PDLSCs, whereas overexpression of CDR1as alleviated the LPS-induced proliferative ability of PDLSCs. Mechanistically, CDR1as functioned as an miR-7 sponge to activate the ERK signal pathway to mediate the inhibition effect of LPS on cell proliferation. Taken together, our findings revealed the effects of the interacting pair of CDR1as/miR-7 on the proliferation ability of PDLSCs within their surrounding inflammatory microenvironment of periodontitis.

Digital planning workflow for partial maxillectomy using an osteotomy template and immediate rehabilitation of maxillary Brown II defects with prosthesis.

BACKGROUND: There is increasing evidence of benefits for the rehabilitation of Brown II defects with prosthesis in surgery. However, the current literature is sparse for maxillary tumour resection using osteotomy templates. OBJECTIVES: To assess the accuracy of maxillectomy using a custom fabricated osteotomy template and to evaluate the prosthesis for surgical accuracy, appearance and functioning (speech, swallowing and occlusal force). METHODS: Ten patients with Brown II defects caused by tumour resection were treated with precise partial maxillectomy using an osteotomy template. The immediate rehabilitation of the Brown II defect was completed with a prefabricated prosthesis. The post-operative three-dimensional images and the pre-operative virtual images were superimposed, and average deviation and maximum deviation were calculated. Speech intelligibility, swallowing, appearance and University of Washington Quality of Life Questionnaire (UW-QoL) were examined at 1, 3 and 6 months after surgery. Occlusal force was examined post-operatively at 6 months. RESULTS: The maximum deviation between the actual and virtual surgery was 5.12 ± 0.44 mm, with an average of 1.02 ± 0.17 mm. Speech intelligibility, swallowing and UW-QoL improved significantly (P < .05) after wearing the prosthesis. The recovery index of the occlusal force on the affected side was 20.19%-32.28%. The skewed degree of the mouth corner, the difference in the height of the left and right lips, the maximum deviation distance and the change area volume decreased significantly (P < .05). CONCLUSION: The precise rehabilitation of maxillary Brown II defects can be achieved using a prosthesis fabricated with an osteotomy template. The prosthesis restored appearance and functional capabilities (such as speech and occlusal force).

Advanced biomaterials and their potential applications in the treatment of periodontal disease.

Periodontal disease is considered as a widespread infectious disease and the most common cause of tooth loss in adults. Attempts for developing periodontal disease treatment strategies, including drug delivery and regeneration approaches, provide a useful experimental model for the evaluation of future periodontal therapies. Recently, emerging advanced biomaterials including hydrogels, films, micro/nanofibers and particles, hold great potential to be utilized as cell/drug carriers for local drug delivery and biomimetic scaffolds for future regeneration therapies. In this review, first, we describe the pathogenesis of periodontal disease, including plaque formation, immune response and inflammatory reactions caused by bacteria. Second, periodontal therapy and an overview of current biomaterials in periodontal regenerative medicine have been discussed. Third, the roles of state-of-the-art biomaterials, including hydrogels, films, micro/nanofibers and micro/nanoparticles, developed for periodontal disease treatment and periodontal tissue regeneration, and their fabrication methods, have been presented. Finally, biological properties, including biocompatibility, biodegradability and immunogenicity of the biomaterials, together with their current applications strategies are given. Conclusive remarks and future perspectives for such advanced biomaterials are discussed.

Porous nano-hydroxyapatite/collagen scaffold containing drug-loaded ADM-PLGA microspheres for bone cancer treatment.

To develop adriamycin (ADM)-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles in a porous nano-hydroxyapatite/collagen scaffold (ADM-PLGA-NHAC). To provide novel strategies for future treatment of osteosarcoma, the properties of the scaffold, including its in vitro extended-release properties, the inhibition effects of ADM-PLGA-NHAC on the osteosarcoma MG63 cells, and its bone repair capacity, were investigated in vivo and in vitro. The PLGA copolymer was utilized as a drug carrier to deliver ADM-PLGA nanoparticles (ADM-PLGA-NP). Porous nano-hydroxyapatite and collagen were used to materials to produce the porous nano-hydroxyapatite/collagen scaffold (NHAC), into which the ADM-PLGA-NP was loaded. The performance of the drug-carrying scaffold was assessed using multiple techniques, including scanning electron microscopy and in vitro extended release. The antineoplastic activities of scaffold extracts on the human osteosarcoma MG63 cell line were evaluated in vitro using the cell counting kit-8 (CCK8) method and live-dead cell staining. The bone repair ability of the scaffold was assessed based on the establishment of a femoral condyle defect model in rabbits. ADM-PLGA-NHAC and NHAC were implanted into the rat muscle bag for immune response experiments. A tumor-bearing nude mice model was created, and the TUNEL and HE staining results were observed under optical microscopy to evaluate the antineoplastic activity and toxic side effects of the scaffold. The composite scaffold demonstrated extraordinary extended-release properties, and its extracts also exhibited significant inhibition of the growth of osteosarcoma MG63 cells. In the bone repair experiment, no significant difference was observed between ADM-PLGA-NHAC and NHAC by itself. In the immune response experiments, ADM-PLGA-NHAC exhibited remarkable biocompatibility. The in vivo antitumor experiment revealed that the implantation of ADM-PLGA-NHAC in the tumor resulted in a improved antineoplastic effect and fewer adverse side effects than direct intraperitoneal injection of ADM. The ADM-PLGA-NHAC developed in this study exhibited excellent extended-release drug properties, bone repairing and antineoplastic efficacy, which make it a promising osteoconductivity material with the capability to inhibit osteosarcoma.

Effect of Reinforcement Bar on Trueness of Printed Titanium Kennedy I Removable Partial Denture Frameworks by Selective Laser Melting.

OBJECTIVE: The addition of reinforcement bars is a commonly used method to improve the fabrication trueness of selective laser melting removable partial denture alloy frameworks. However, the effects of different reinforcement bar designs on the trueness of the entire framework remain unclear. This study investigated the trueness of removable partial denture frameworks of pure titanium fabricated by selective laser melting under different reinforcement bar settings. METHOD: A virtual framework was designed based on the Kennedy Class I partially edentulous model using computer-aided design software. Frameworks with different reinforcement bar settings (Ti-A without reinforcement bar, Ti-B with a single horizontal bar joining the lingual bar, Ti-C with two more bars at the anterior region, Ti-D with another horizontal bar at the anterior region, and Ti-E with one more bar at the posterior region, n = 5) were printed using pure titanium powder using a direct metal laser melting machine. The fabricated frameworks were scanned, and their fabrication trueness was compared with the designed virtual framework using one-way ANOVA. RESULTS: The overall mean discrepancies for Ti-A, Ti-B, Ti-C, Ti-D, and Ti-E were 0.111, 0.047, 0.073, 0.068, and 0.047 mm, respectively. For the group of Ti-A set with no reinforcement bars, larger discrepancies were observed compared with the other four groups (P < .05). Groups Ti-B and Ti-E showed better trueness of the RPI clasps, rests, and distal ends (P < .05). CONCLUSIONS: Adding reinforcement bars improved the printing trueness of the pure titanium frameworks, and different settings resulted in various degrees of improvement. Setting a single reinforcement bar to join the lingual bar or an additional reinforcement bar at the distal end significantly enhanced the printing trueness of the RPI clasps, rests, and distal ends.

Influence of 3D printed surface micro-structures on molding performance and dental bonding properties of zirconia.

OBJECTIVES: To investigate the influence of the 3D printed micro-structured surfaces on the bond strength of zirconia to resin cement. METHODS: Zirconia specimens were divided into five groups based on manufacturing technique and surface preparation: (1) milled zirconia (M group); (2) milled zirconia airborne abraded (MA group); (3) printed zirconia (M group); (4) printed zirconia airborne abraded (PA group); and (5) printed zirconia with micro-structured surface (PM group). The surface morphology, cross-sectional morphology, and elemental composition were observed using a scanning electron microscope (SEM). Surface roughness was measured using a laser scanning confocal microscope (SLCM). Shear bond strength (SBS) was measured using a universal testing machine after bonding resin cement (n = 10). The failure modes of the bonded fracture interfaces were observed and counted using a stereomicroscope and a SEM. In addition, boundary dimensional accuracy (n = 10) and micro-structural dimensional accuracy (n = 20) of printed zirconia specimens with micro-structured surfaces were measured using digital calipers and Fiji software. The crystalline phase changes before and after surface treatment were investigated using X-ray diffractometry. Data was analysed using one-way ANOVA and Tukey HSD post-hoc tests (α = 0.05). RESULT: The surface micro-structures of the PM group had regular morphology and no obvious defects. The surface roughness results showed that the PM group had higher Sa (42.21±1.38 um) and Ra (21.25±1.80 um) values than the other four groups (p < 0.001). The SBS test showed that the bond strength of the PM group reached 11.23 ± 0.66 MPa, which was 55.97% (p < 0.001) higher than that of the P group (7.20 ± 1.14 MPa). The boundary dimensional accuracy of the PM group was proficient (diameter: 99.63 ± 0.31%, thickness: 98.05 ± 1.12%), and the actual fabrication dimensions of the hexagonal micro-structures reached 77.45%-80.01% of the original design. The micro-structured surface did not affect the crystalline phase of zirconia. CONCLUSIONS: The current study illustrates that 3D-printed microstructured surfaces effectively improve the bond strength of zirconia to resin cements. CLINICAL SIGNIFICANCE: With the advantage of 3D printing, this study provides a new idea for improving the bonding properties of zirconia.

Comparison of selective laser melting and stereolithography etching templates for guided endodontics.

Background: With the increasing application of guided endodontics to treat complex root canal treatment, the entire process of root canal treatment has become more precise, reducing damage to tooth structure and improving success rates. However, due to the limitations of the operating space, the use of guided endodontic templates in posterior root canal treatment is less common. This study aims to compare the accuracy and reliability of selective laser melting (SLM) and traditional stereolithography etching (SLA) guided endodontic templates for posterior root canals, providing better treatment strategies for posterior root canal treatment. Methods: The teeth were randomly assigned to either SLM or SLA group. Preoperative cone-beam computed tomography (CBCT) and a three-dimensional (3D) scanner were used to establish the 3D root canal system and the accurate occlusal models of the teeth. The virtual access to the canal access was designed using Mimics 19.0 and 3-Matic 11.0. The endodontic access was performed based on either SLM or SLA templates. The accuracy of endodontic preparation was measured in three-dimensions by calculating deviations from planned accesses. The template height and tooth substance loss rates in each group were measured. Results: SLM-guided templates have a low average deviation at the entry point and apical portion of the bur of total posterior teeth (including premolars and molars) and individual molars (P < 0.05). Moreover, there was a significant difference in angular deviations and height of template in total posterior teeth and individual molars (P < 0.05). The mean substance loss rate of the SLA group was slightly greater than that of the SLM group, but the difference was not statistically (P > 0.05). Conclusions: SLM-guided endodontics provides a more predictable and precise location of root canal orifice for the treatment of posterior teeth.

Evaluation of Chitosan-Oleuropein Nanoparticles on the Durability of Dentin Bonding.

Purpose: To evaluate the effects of dentin pretreatment with chitosan-loaded oleuropein nanoparticles (CONPs) on the durability of resin-dentin bonding interfaces. Methods: Eighty freshly extracted non-carious human third molars were randomly divided into four groups (n = 20 each): a de-ionized water (DW) group, a chitosan (CS) group, a chlorhexidine (CHX) group and a CONP group. The dentin in the DW, CS, CHX, and CONP groups were pretreated with de-ionized water, 1.0 mg/L CS solution, 2% chlorhexidine solution, and CONP suspension (prepared with 100 mg/L oleuropein), respectively, followed by the universal adhesive and resin composites. The bonded teeth of each group were randomly divided into two subgroups: an immediate subgroup and an aged subgroup. The bonded teeth of each group were then cut into the bonded beams. We measured their microtensile bond strength (µTBS), observed the characteristics of bonding interface by atomic force microscope, calculated the percentage of silver particles in a selected area for interfacial nanoleakage analysis, and evaluated the endogenous gelatinase activity within the bonding interface for in-situ zymogram analysis. Data were analyzed with two-way ANOVA and LSD multiple comparison test (P < 0.05). Results: Regardless of after 24 h or after thermocycling, CONP exhibited better µTBS (P < 0.05) than the other three groups except that there was not a statistical significance (P > 0.05) in the CONP and CHX groups after 24 h. Besides, the CONP group presented significantly higher modulus of elasticity in the hybrid layers (P < 0.05), lower expression of nanoleakage (P < 0.05), and better inhibitory effect of matrix metalloproteinases than the other three groups before and after thermocycling. Conclusion: Altogether, the CONPs had the potential to act as a dentin primer, which could effectively improve the dentin-resin binding durability.

Regulatory mechanisms of GCN5 in osteogenic differentiation of MSCs in periodontitis.

OBJECTIVES: The regulatory mechanisms of GCN5 (General control non-repressed protein5) in the osteogenic differentiation of mesenchymal stem cells (MSCs) in periodontitis are still unclear. The purpose of this review focuses on the regulating roles of GCN5 in bone metabolism and periodontitis, discusses the potential molecular mechanism and provides targets and new ideas for the treatment of periodontitis. MATERIAL AND METHODS: The integrative review methodology was used. Data sources include PubMed, Cochrane Library, and additional sources. RESULTS: MSCs play an important role in the osteogenesis balance of periodontal tissue. Periodontal ligament stem cells (PDLSCs) from periodontitis patients exhibited defective osteogenic differentiation capacities. Histone acetylation is important in regulating the differentiation of different types of MSCs cells and is closely related to the reduced osteogenic differentiation of PDLSCs. GCN5, one of the first histone acetyltransferase linked to gene transcriptional activation, participates in many biological processes of mesenchymal stem cells. Downregulation of GCN5 expression and lack of GCN5 caused decreased osteogenic differentiation of PDLSCs. Intercellular information exchange may be an important way for MSCs to exert their regulatory and therapeutic functions. CONCLUSIONS: GCN5 affects the function of cell metabolism-related genes by regulating the acetylation status of histones or non-histones, thereby regulating some important progress of MSCs such as PDLSCs' osteogenic differentiation and BMCS osteogenic differentiation.

Effect of chitosan-oleuropein nanoparticles on dentin collagen cross-linking.

BACKGROUND: The integrity and stability of collagen are crucial for the dentin structure and bonding strength at dentin-resin interface. Natural plant-derived polypehenols have been used as collagen crosslinkers. OBJECTIVE: The aims of the study were to develop novel chitosan oleuropein nanoparticles (CS-OL-NPs), and to investigate the CS-OL-NPs treated dentin's the resistance to enzymatic degradation and mechanic property. METHODS: CS-OL-NPs were developed using the ionotropic gelation method. Release and biocompatibility of the CS-OL-NPs were tested. Twenty demineralized dentin collage specimens were randomized into four interventions groups: A, Deionized Water (DW); B, 5% glutaraldehyde solution (GA); C, 1 mg/ml chitosan (CS); and D, 100 mg/L CS-OL-NPs. After 1-min interventions, dentin matrix were evaluated by the micro-Raman spectroscopy for the modulus of elasticity test. Collagen degradation was assessed using hydroxyproline (HYP) assay. RESULTS: CS-OL-NPs were spherical core-shape with a size of 161.29 ± 8.19 nm and Zeta potential of 19.53 ± 0.26 mV. After a burst release of oleuropein in the initial 6 h, there was a long-lasting steady slow release. CS-OL-NPs showed a good biocompatibility for the hPDLSCs. The modulus of elasticity in the crosslinked groups were significantly higher than that in the control group (P< 0.05 for all). The specimens treated with CS-OL-NP showed a greater modulus of elasticity than those treated with GA and CS (P< 0.05 for both). The release of HYP in the crosslinked group was significantly lower than that in the non-crosslinked groups (P< 0.05 for all). CONCLUSION: CS-OL-NPs enhanced the dentin mechanical property and resistance to biodegradation, with biocompatibility and potential for clinical application.

Consensus on the preparation margin and restoration margin in ceramic esthetic rehabilitation.

In esthetic rehabilitation, methods used to enhance the margin quality have always been the focus and difficulty of improving the level of diagnosis and treatment, prevention and treatment of complications, and collaboration between clinicians and technicians. However, it is impeded by the ambiguous definition and classification of margin, unstandardized tooth preparation, manufacturing process of restoration, and lack of reliable means of checking the quantitative requirements of preparation or restoration. The digital technologies that are increasingly applied, such as intra-oral scanner, impression scanner, and computerized numerical control cutting machine, have strict requirements about margin quality. Failure of recognizing margins by these scanners will hinder the digital process of diagnosis and treatment. Even if these sharp and narrow margins are successfully scanned, they cannot be milled accurately. To overcome these problems, this article demonstrated the clear and complete definition of preparation margin and restoration margin, as well as their subclassifications, by analyzing the target restoration space from a geometric perspective. Practical approaches to measuring the margin width and inspecting the margin quality were proposed. The new and full understanding and proposal about preparation margin and restoration margin characterized by measurements will effectively support the thoroughly digitalized process of esthetic rehabilitation using porcelain in fixed prosthodontics, which is based on the guidance of values.