Targeted pH-responsive chitosan nanogels with Tanshinone IIA for enhancing the antibacterial/anti-biofilm efficacy.

Persistent bacterial infection caused by biofilms is one of the most serious problems that threatened human health. The development of antibacterial agents remains a challenge to penetrate biofilm and effectively treat the underlying bacterial infection. In the current study, chitosan-based nanogels were developed for encapsulating the Tanshinone IIA (TA) to enhance the antibacterial and anti-biofilm efficacy against Streptococcus mutans (S. mutans). The as-prepared nanogels (TA@CS) displayed excellent encapsulation efficiency (91.41 ± 0.11 %), uniform particle sizes (393.97 ± 13.92 nm), and enhanced positive potential (42.27 ± 1.25 mV). After being coated with CS, the stability of TA under light and other harsh environments was greatly improved. In addition, TA@CS displayed pH responsiveness, allowing it to selectively release more TA in acidic conditions. Furthermore, the positively charged TA@CS were equipped to target negatively charged biofilm surfaces and efficiently penetrate through biofilm barriers, making it promising for remarkable anti-biofilm activity. More importantly, when TA was encapsulated into CS nanogels, the antibacterial activity of TA was enhanced at least 4-fold. Meanwhile, TA@CS inhibited 72 % of biofilm formation at 500 µg/mL. The results demonstrated that the nanogels constituted CS and TA had antibacterial/anti-biofilm properties with synergistic enhanced effects, which will benefit pharmaceutical, food, and other fields.

Effect of a novel interocclusal recording method on occlusal accuracy of implant-supported fixed prostheses: A randomized clinical trial.

OBJECTIVES: To investigate the effect of a novel interocclusal recording method on the occlusal accuracy of implant-supported fixed prostheses for partially dentate patients with distal extension. MATERIALS AND METHODS: Twenty patients with two or more adjacent teeth missing in the distal extension and scheduled to receive implant-supported fixed prostheses were enrolled. Two interocclusal recording methods were used: placing polyvinyl siloxane (PVS) on the interocclusal recording caps (test), and placing PVS on healing abutments (control). The intraoral occlusal contacts in maximal intercuspal position (MIP) were compared with those in the mounted casts to calculate sensitivity and positive predictive value (PPV). Then, patients were randomly allocated into two groups to determine which interocclusal record would be used. The implant prostheses' evaluations mainly included occlusal adjustment height, volume, and time, occlusal contact score based on articulating paper examination. Paired-samples t-test, Mann-Whitney U test, and least squares regression analyzed the statistic differences. RESULTS: The test method had higher sensitivity to detect intraoral occlusal contacts than the control method (p = .002), but similar PPV (p = .10). During the prostheses' evaluations, the occlusal adjustment height in the test group was significantly lower than that in the control group [99.4 (53.2, 134.2) vs. 159.0 (82.3, 247.8) µm, p = .03], while the occlusal contact score before adjustment was higher (p = .006). The groups had similar occlusal adjustment volume and time. CONCLUSIONS: The novel interocclusal recording method for implant-supported fixed prostheses was more accurate and could reduce the occlusal adjustment.

Chitosan nanoparticles efficiently enhance the dispersibility, stability and selective antibacterial activity of insoluble isoflavonoids.

Natural isoflavonoids have attracted much attention in the treatment of oral bacterial infections and other diseases due to their excellent antibacterial activity and safety. However, their poor water solubility, instability and low bioavailability seriously limited the practical application. In this study, licoricidin-loaded chitosan nanoparticles (LC-CSNPs) were synthesized by self-assembly for improving the dispersion of licoricidin (LC) and strengthening antibacterial and anti-biofilm performance. Compared to free LC, the minimum inhibitory concentration of LC-CSNPs against Streptococcus mutans decreased >2-fold to 26 µg/mL, and LC-CSNPs could ablate 70 % biofilms at this concentration. The enhanced antibacterial activity was mainly attributed to the spontaneous surface adsorption of LC-CSNPs on cell membranes through electrostatic interactions. More valuably, LC-CSNPs had no inhibitory effect on the growth of probiotic. Mechanism study indicated that LC-CSNPs altered the transmembrane potential to cause bacterial cells in a hyperpolarized state, generating ROS to cause cells damage and eventually apoptosis. This work demonstrated that the chitosan-based nanoparticles have great potential in enhancing the dispersibility and antibacterial activity of insoluble isoflavonoids, offering a promising therapeutic strategy for oral infections.

Accuracy of a milled digital implant surgical guide: An in vitro study.

STATEMENT OF PROBLEM: An accurate surgical template for guided implant surgery is essential for the success of an implant restoration. However, reports on the accuracy of digitally designed and computer numeric controlled (CNC) machine-milled surgical templates are sparse. PURPOSE: The purpose of this in vitro study was to investigate the accuracy of an implant surgical guide digitally designed by using data from cone beam computed tomography (CBCT) scans and milled with a 5-axis CNC machine. MATERIAL AND METHODS: Six representative radiographic templates were prepared from radiopaque resin plates. For each guide, a CBCT scan was made, and the extracted Digital Imaging and Communications in Medicine (DICOM) data were imported into a planning software program (ORGANICAL Dental Implant). Nine implants were virtually designed for each guide. The design data were imported into a 5-axis CNC machine, and the radiographic guides were fixed onto the CNC machine (Organical Multi S). Bore holes for surgical guide sleeves were milled directly in the radiographic template, which was converted into a surgical template. After the milling process, the surgical guides were scanned by using a laboratory cast scanner. The deviation between the position of the sleeve bore hole in the milled template and that in the virtual implant planning was digitally calculated. RESULTS: The mean global deviation of the surgical guide was 0.16 ±0.06 mm in the circle center of the sleeve top, and the mean angular deviation was 0.61 ±0.40 degrees. The sleeve-implant distance and the sleeve axis angle showed no significant influence on the in vitro accuracy of the implant surgical guide. CONCLUSIONS: The mean deviation of the surgical guide prepared by using the virtual planning software program and 5-axis CNC milling procedure in this study was 0.16 ±0.06 mm in the center of the sleeve top. Thus, the guide had acceptable precision.

Microbiological and clinical evaluation of ultrasonic debridement with/without erythritol air polishing during supportive periodontal therapy in arches with full-arch fixed implant-supported prostheses: protocol for a randomised controlled trial.

INTRODUCTION: Implant-supported prostheses are often successfully used in edentulous patients. However, the incidences of peri-implant mucositis and peri-implantitis increase over time. The accumulation of pathogenic bacteria adjacent to prostheses can induce peri-implant disease. Plaque removal is recommended to prevent and manage peri-implant diseases. The purpose of this study is to compare the plaque removal efficacy of ultrasonic debridement with/without erythritol air-polishing powder around implants and bridges in patients with full-arch fixed implant-supported prostheses as well as the effects of these two methods on the rates of peri-implant mucositis and peri-implantitis, and the submucosal microbiota composition over 5 years in patients undergoing supportive periodontal therapy. METHODS AND ANALYSIS: We plan to enrol 10 edentulous (maxilla and/or mandible) patients seeking full-arch fixed implant-supported prostheses. The study will use a split-mouth model in which contralateral quadrants are randomly assigned to two groups. Group 1: one contralateral quadrant of full-arch fixed implant-supported prostheses will undergo ultrasonic debridement combined with erythritol air-polishing powder. Group 2: a separate contralateral quadrant of full-arch fixed implant-supported prostheses will undergo ultrasonic debridement. The 5-year trial will involve a total of 10 re-examinations per participant. The mucosal conditions around the implants will be recorded at 6-month intervals after restoration. Peri-implant submucosal plaque will be collected at each re-examination, and the bacterial flora will be analysed by 16s ribosomal RNA gene sequencing. X-ray examinations will be conducted at 12-month intervals to evaluate the marginal bone level around implants. ETHICS AND DISSEMINATION: This prospective single-centre, randomised controlled trial (PKUSSIRB-202054045) has been approved by the Ethics Committee of Stomatology School and Hospital of Peking University. Data will be registered with the International Clinical Trials Registry Platform. Additionally, we will disseminate the results via publication in scientific journals. TRIAL REGISTRATION NUMBER: ChiCTR-2000032431.

A review about the application of phonetic methods in deciding the jaws relation of complete denture.

Speech could be used, because it was a neuromuscular movement without teeth contact. The method was stable, however it was used more in vertical relation deciding. More study was needed in the horizontal relation deciding. This article was to explain why and how to use phonetic method to decide jaws relation, through literature review.

Comparison of peri-implant submucosal microbiota in arches with zirconia or titanium implant-supported fixed complete dental prostheses: a study protocol for a randomized controlled trial.

BACKGROUND: The success rate of implant-supported prostheses for edentulous patients is relatively high. However, the incidence of biological complications, especially peri-implant mucositis and peri-implantitis, increases yearly after the placement of prostheses. The accumulation of pathogenic bacteria adjacent to a prosthesis is the main cause of biological complications. Titanium, one of the classical materials for implant-supported prostheses, performs well in terms of biocompatibility and ease of maintenance, but is still susceptible to biofilm formation. Zirconia, which has emerged as an appealing substitute, not only has comparable properties, but presents different surface properties that influence the adherence of oral bacteria. However, evidence of a direct effect on oral flora is limited. Therefore, the aim of the present study was to assess the effects of material properties on biofilm formation and composition. METHODS: The proposed study is designed as a 5-year randomized controlled trial. We plan to enroll 44 edentulous (mandible) patients seeking full-arch, fixed, implant-supported prostheses. The participants will be randomly allocated to one of two groups: group 1, in which the participants will receive zirconia frameworks with ceramic veneering, or group 2, in which the participants will receive titanium frameworks with acrylic resin veneering. Ten follow-up examinations will be completed by the end of this 5-year trial. Mucosal conditions around the implants will be recorded every 6 months after restoration. Peri-implant submucosal plaque will be collected at each reexamination, and bacteria flora analysis will be performed with 16S rRNA gene sequencing technology in order to compare differences in microbial diversity between groups. One week before each visit, periodontal maintenance will be arranged. Each participant will receive an X-ray examination every 12 months as a key index to evaluate the marginal bone level around the implants. DISCUSSION: The current study aims to explore the oral microbiology of patients following dental restoration with zirconia ceramic frameworks or titanium frameworks. The features of the microbiota and the mucosal condition around the two different materials will be evaluated and compared to determine whether zirconia is an appropriate material for fixed implant-supported prostheses for edentulous patients. TRIAL REGISTRATION: International Clinical Trials Registry Platform (ICTRP) ChiCTR2000029470. Registered on 2 February 2020. http://www.chictr.org.cn/searchproj.aspx?

Accuracy of implant surgical guides fabricated using computer numerical control milling for edentulous jaws: a pilot clinical trial.

BACKGROUND: To evaluate the accuracy of a computer numerical control (CNC) milled surgical guide for implant placement in edentulous jaws. METHODS: Edentulous patients seeking implants treatment were recruited in this prospective cohort study. Radiographic guides with diagnostic templates were fabricated from wax-up dentures. Patients took cone-beam computed tomography (CBCT) wearing the radiopaque radiographic guides. Implant positions were virtually designed in the planning software based on the CBCT data, and the radiographic templates were converted into surgical guides using CNC milling technique. Forty-four implants were placed into 12 edentulous jaws following guided implant surgery protocol. Post-surgery CBCT scans were made for each jaw, and the deviations between the planned and actual implant positions were measured. Deviation of implant position was compared between maxilla and mandible, and between cases with and without anchor pins using independent t-test. RESULTS: Nine patients (3 males and 6 females) with 12 edentulous jaws were recruited. The mean age of patients was 59.2 ± 13.9 years old. All 44 implants was placed without complication and survived, the mean three dimensional linear deviation of implant position between virtual planning and actual placement was 1.53 ± 0.48 mm at the implant neck and 1.58 ± 0.49 mm at the apex. The angular deviation was 3.96 ± 3.05 degrees. No significant difference was found in the deviation of implant position between maxilla and mandible (P = 0.28 at neck, 0.08 at apex), nor between cases with and without anchor pins (P = 0.87 at neck, 0.06 at apex). CONCLUSIONS: The guides fabricated using the CNC milling technique provided comparable accuracy as those fabricated by Stereolithography. The displacement of the guides on edentulous arch might be the main contributing factor of deviation. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR-ONC-17014159 (July 26, 2017).

The Effectiveness of Waist-Shaped and Straight-Shaped Interdental Brushes in Cleaning Implant Overdenture Attachments: A Self-Controlled Clinical Trial.

Elderly patients often find it challenging to remove plaque accumulated on the attachments of implant overdentures (IODs) using conventional cleaning instruments. Further, excessive plaque accumulation can lead to peri-implant diseases and occasionally to respiratory diseases. Therefore, here, we aimed to compare the effectiveness of waist-shaped interdental brushes (WIBs) with that of straight-shaped interdental brushes (SIBs) in plaque removal from the locator attachments of IODs. Twenty participants with 2 locator attachments retaining mandibular IODs participated in this study. After the baseline cleaning, the participants refrained from oral hygiene maintenance for 3 days. A dentist cleaned 1 of the attachments using the WIB and the other attachment using the SIB. The pre- and post-cleaning modified plaque index (mPLI) scores were recorded. After another 3 days free from oral hygiene maintenance, the trained participants repeated the same cleaning procedure using the WIB and SIB. Pre- and post-cleaning mPLI scores were recorded. Regardless of the type of brush used, the post-cleaning mPLI scores were lower than the pre-cleaning scores. After the cleaning procedure, the overall mean mPLI score was lower in the WIB group than in the SIB group. The post-cleaning mPLI scores at the line angles and on the axial surfaces of the attachments were also lower in the WIB group than in the SIB group. There was no difference in the cleaning effectiveness between the dentist and participants when they used the same type of interdental brush. The WIB was significantly more efficient in plaque removal than the SIB, especially at the line-angle sites.

Early loading of splinted implants in posterior mandible: Three-year results of a prospective multicenter study.

OBJECTIVE: To evaluate the clinical outcomes of an early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design for the therapy of posterior partial edentulism of mandible. MATERIALS AND METHODS: One hundred and seven implants were placed in the mandible of 45 subjects at three centres in China. A minimum of two and a maximum of three implants were placed in an edentulous region using a one-stage protocol. Each subject received a screw-retained, splinted and fixed permanent prosthesis 6-8 weeks after surgery. Marginal bone level (MBL) change, implant survival and soft tissue health were assessed at 6, 12, 24 and 36 months after loading. A total of 92 implants from 40 subjects were recalled and investigated in this clinical trial. RESULTS: After three-year loading, the survival rate of implant was 100%. On a subject level, there was a mean (±SD) marginal bone gain of 0.23 ± 0.48 mm at 36-month recall and the change in MBL was statistically significant (p = .00061) compared with time of loading. On an implant level, the change in MBL was statistically significant (p = .03914, p = .01494, p = .00000) at 12, 24 and 36 months of loading compared with time of loading. CONCLUSION: Three-year data indicate that early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design is feasible and safe for the therapy of partial edentulism in posterior mandible, which may contribute to bone gain when the suitable occlusal load and oral hygiene maintenance are kept.

Closing open contacts adjacent to an implant-supported restoration.

Loss of interproximal contact between fixed implant-supported restorations and the adjacent teeth is one of the most common complications in implant dentistry. This article presents a clinical chairside technique for closing open contacts adjacent to an implant-supported restoration. A silicon model is perfused from a restoration-level impression using the open tray technique. Composite resin is bonded to the implant-supported ceramic restoration extraorally to restore the interproximal contact. The tooth and restoration contact is double confirmed on the silicon model and in the mouth. This chairside procedure may save time and improve patient comfort.

Passively fitting implant-supported complete-arch interim restoration.

This article presents a technique for fabricating a passively fitting implant-supported screw-retained complete-arch interim restoration with resistance to early fracture. Two gypsum casts were obtained from an implant impression using the splinting technique. The complete-arch interim restoration with abutment access holes, which was reinforced with a glass fiber splint, was fabricated on one cast and connected to restorative abutments on the other cast extraorally to eliminate stresses from the polymerization shrinkage of resin.

An implant impression technique involving abutment transition from interim prostheses to definitive restorations in the esthetic zone.

This article presents an impression technique involving transfer of the position of implants and the emergence profile of splinted interim prostheses fabricated on nonindexed interim abutments to definitive single crowns fabricated on indexed abutments.

[The modified lip-tooth-ridge classification: a guide for edentulous maxillary arches].

According to the width and height of the maxillary alveolar ridge, the maxillary edentulous jaws can be divided into three categories by using modified lip-tooth-ridge (MLTR) classification. Class Ⅰ is characterized by sufficient bone available for implants in the vertical and horizontal aspects and is suitable for fixed implant-supported prostheses. Class Ⅱ is characterized by sufficient bone amount available for implants in a horizontal aspect but insufficient for lip support and is suitable for a fixed detachable implant-supported prosthesis. Class Ⅲ is characterized by inadequate amount of bone for implants (with vertical or horizontal components) and is suitable for the use of zygomatic implants or traditional complete denture. Patients belonging to Class Ⅰ can be further classified into two sub-categories according to the height of the alveolar ridge. The first subclass is characterized by minimal bone deficiency and is suitable for a conventional implant-supported "crown and bridge" prosthesis. The second subclass is characterized by a larger vertical deficiency than that of the first subclass and is suitable for implant-supported hybrid prosthesis. The MLTR classification system can help the dentist to determine whether the patient is suitable for implanting dentures and whether fixed denture or removable denture is appropriate for the patient, select indications, reduce complications, and achieve long-term results.

Effects of thermal treatment on the adhesion strength and osteoinductive activity of single-layer graphene sheets on titanium substrates.

In recent years, dental implants have become the preferred approach for the restoration of missing teeth. At present, most dental implants are made of pure titanium, and are affected by peri-implantitis and bone resorption, which usually start from the implant neck, due to the complex environment in this region. To address these issues, in this study we modified the surface of titanium (Ti) implants to exploit the antibacterial and osteoinductive effects of single-layer graphene sheets. Chemical vapor deposition (CVD)-grown single-layer graphene sheets were transferred to titanium discs, and a method for improving the adhesion strength of graphene on Ti was developed due to compromised adhesion strength between graphene and titanium surface. A thermal treatment of 2 h at 160 °C was found to enhance the adhesion strength of graphene on Ti to facilitate clinical transformation. Graphene coatings of Ti enhanced cell adhesion and osteogenic differentiation, and imparted antibacterial activity to Ti substrate; these favorable effects were not affected by the thermal treatment. In summary, the present study elucidated the effects of a thermal treatment on the adhesion strength and osteoinductive activity of single-layer graphene sheets on titanium substrates.

A digital technique for fabricating implant-supported interim restorations in the esthetic zone.

A digital technique for fabricating an implant-supported interim restoration is presented. The labial cervical architecture of the natural tooth is captured before extraction and registered to form the emergence profile of the interim restoration. A well-contoured interim restoration is fabricated before surgery and connected to the immediately placed implant with a customized interim abutment.

A digital technique for replicating peri-implant soft tissue contours and the emergence profile.

A digital technique is presented that records peri-implant soft tissue contours and the emergence profile. The architecture of interim restorations and adjacent teeth, the position of the implant, and the emergence profile of interim prostheses are scanned and registered to design a zirconia frame and to form a digital cast.

Effect of Voluntary Wheel Running on Striatal Dopamine Level and Neurocognitive Behaviors after Molar Loss in Rats.

The aim of the present study is to evaluate the effect of voluntary wheel running on striatal dopamine level and behavior of cognition and emotion in molar loss rats. Twenty-four Sprague-Dawley rats were enrolled in this study and randomly divided into following 4 groups: control group (C group), molar loss group (ML group), 1-week physical exercise before molar loss group (1W-ML group), and 4-week physical exercise before molar loss group (4W-ML group). The rats both in 4W-ML and 1W-ML groups were placed in the voluntary running wheel in order to exercise for 4 weeks and 1 week, respectively. Then, the rats in 4W-ML, 1W-M, and ML groups received bilateral molar loss operation. After 10 days, striatal dopamine level was detected by in vivo microdialysis coupled with high-performance liquid chromatography (HPLC) and electrochemical detection. All the rats received behavior test after microdialysis detection. The behavior tests including passive avoidance test were used to assess cognition and elevated plus maze test for emotion. The results indicated that voluntary wheel running promoted striatal dopamine level in rats of molar loss. Behavioral data indicated that voluntary wheel running promoted cognition and emotion recovery after molar loss. Therefore, we concluded physical exercise significantly improved the neurocognitive behaviors and increased the striatal dopamine level after molar loss in rats.

Single-Layer Graphene Enhances the Osteogenic Differentiation of Human Mesenchymal Stem Cells In Vitro and In Vivo.

In recent years, although several studies have demonstrated the potential of graphene-coated substrates in promoting attachment, proliferation and differentiation of osteoblasts and mesenchymal stem cells (MSCs), the effects of single-layer graphene on the osteogenic differentiation of human MSCs (hMSCs) remains unclear, especially in vivo. In this study, we transferred chemical vapor deposition (CVD) grown single-layer graphene to glass slides and observed its effects on adhesion, proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs) and human bone marrow mesenchymal stem cells (hBMMSCs) in vitro. Then, in vivo, we incubated hASCs and hBMMSCs on single-layer graphene-coated smooth titanium (Ti) disks before implanting them into the back subcutaneous area of nude mice. We found that single-layer graphene accelerated cell adhesion to the substrate without influencing cell proliferation of hMSCs. Moreover, we present the first study that explores the epigenetic role of single-layer graphene in determining stem cell fate. By utilizing epigenetic approaches, we reveal that single-layer graphene promotes osteogenic differentiation of hMSCs both in vitro and in vivo, potentially by upregulating methylation of H3K4 at the promoter regions of osteogenesis-associated genes. Overall, our results highlight the potential of this material in implants and injured tissues in clinical applications.

Comparative in vitro study of cementing techniques for implant-supported restorations.

STATEMENT OF PROBLEM: Various techniques are used to cement implant-supported restorations. Excess residual cement is a concern. PURPOSE: The purpose of this in vitro study was to evaluate 3 techniques for cementing implant-supported restorations. MATERIAL AND METHODS: Twelve crowns and implant-abutment complexes (IAC) were cemented with 3 techniques: technique 1, a certain amount of cement evenly placed and excess cement removed with an explorer; technique 2, a smaller amount of cement without removal of excess cement; technique 3, a resin abutment replica used for excess cement removal after using a large amount of cement. Each specimen was treated with each technique 3 times. Precementing discrepancies (predis) and postcementing discrepancies (postdis) between IACs and crowns and the postcementing linear roughness (Ra and Rz) on designated junction areas of each specimen were measured. Tensile strength of the specimens was recorded with a universal testing machine at a crosshead speed of 0.5 mm/min. Repeated measures analysis with mixed models was used for differences among the 3 cementing techniques (α=.05). RESULTS: Compared with techniques 1 and 2, the specimens with technique 3 showed significantly lower mean differences between postdis and predis and Ra and Rz and higher mean tensile strength (P<.05). CONCLUSIONS: The application of a resin abutment replica for the cementation of implant-supported restorations decreased the discrepancy between the restoration and abutment, reduced cement residue, and increased restoration retention.