Three dimensionally printed template with an interproximal isolation design guide consecutive closure of multiple diastema with injectable resin composite.

OBJECTIVE: This article describes a novel 3D-printed template armed with interproximal matrices to isolate interproximal contact areas and guide injectable resin composite for consecutive closure of multiple diastema. CLINICAL CONSIDERATIONS: Among several treatment options proposed for diastema closure, direct resin composite is noninvasive and easy to repair. The "composite injection technique" has been introduced to improve time efficiency and reduce technique sensitivity for clinicians. However, in the case of multiple diastema, the overflow of excess resin materials onto the adjacent teeth during injection poses challenges for recontouring the interproximal anatomy. A 3D-printed template with special-designed gaps at interproximal areas was designed and fabricated based on a virtual diagnostic wax-up. Flowable resin composite was then consecutively injected through the template to close diastemata at multiple adjacent teeth. CONCLUSION: This technique using a 3D-printed template with interproximal isolation design contributed to an efficient and accurate operation for multiple anterior diastema closure. CLINICAL SIGNIFICANCE: Efficient and accurate freehand buildups of composite restoration for multiple diastema are challenging in operative dentistry. The described noninvasive full digital workflow provides a predictable method to accurately recontour the multiple target restorations and reduce the chair-side time and technical sensitivity.

Digital intraoperative evaluation of restorative space and nontemplate-guided tooth preparation when replacing failed anterior restorations: A dental technique.

Assessing the correlation between the current restorative space and the target restorative space is important in determining whether additional tooth preparation is required when replacing failed prostheses. However, existing techniques are not always accurate or efficient. This article describes a digital workflow for the accurate chairside evaluation of the current restorative space and nontemplate-guided tooth preparation. Reference data was obtained from an initial scan of the existing restoration with an intraoral scanner. After removing the existing restoration, a second scan of the tooth was made and compared with the reference data to evaluate the current restorative space. Subsequently, the abutment tooth was prepared and rescanned, with the restorative space being re-evaluated until it met the requirements. This workflow enables the immediate and accurate evaluation of the restorative space, facilitating accurate chairside tooth preparation without the need for silicone indices or other templates, thereby saving time and cost.

Classified diagnosis and treatment scheme of oral cosmetic restoration based on aesthetic analysis (part â ¡): Chinese aesthetic connotation and analysis scheme.

At present, the commonly used clinical protocols of oral cosmetic restoration are mostly based on the oral aesthetic indexes proposed by Western developed countries (referred to as Western aesthetics), which are different from the oral aesthetic indexes unique to Chinese people (referred to as Chinese aesthetics). In the design of restoration schemes and the evaluation of restoration effects, these differences have a large or small effect on the doctor-patient-technology triad. Improper handling could directly weaken the cooperation efficiency of the three parties, reduce patient satisfaction, and even lead to medical disputes in serious cases. From doing a good job of oral cosmetic restoration in China, the connotative characteristics of Chinese oral aesthetics are introduced in this paper, and the value of oral aesthetic analysis in diagnosis and treatment is discussed. The process and method of aesthetic analysis and assessment through the modified Chinese psychosocial impact of dental aesthetics questionnaire and the evaluation ruler of the expected value of oral cosmetic restoration are further introduced in detail.

Classified diagnosis and treatment scheme of oral cosmetic restoration based on aesthetic analysis (part â ): basic concept, decision tree and clinical pathway.

At present, the commonly used clinical protocols of oral comestic restoration are mostly based on the aesthetic indicators proposed by Western developed countries (referred to as Western aesthetics). Mechanically copying the Western aesthetic scheme, ignoring the difference between it and the Chinese oral aesthetic indicators (referred to as Chinese aesthetics), is unable to effectively support personalized cosmetic restoration diagnosis and treatment. In addition, new technologies and new solutions for cosmetic restoration, which are developing rapidly in recent years, are emerging one after another, but many popular concepts are confusing and lack of proper hierarchical diagnosis and treatment norms, and there is indeed an urgent need for discussion and clarity. From the perspective of serving clinical application, this paper discusses the deficiencies of the Chinese translation of the word "aesthetics", the diffe-rence and connection between aesthetics and cosmetology, and the relationship between cosmetic restoration and fixed restoration. It also discusses the difference between anterior teeth, esthetic zone and exposed zone, the diagnostic and therapeutic value of oral aesthetic analysis, as well as the application methods of desensitization, suggestion, and other therapies in difficult oral cosmetic restoration cases. We further introduce the decision tree and the clinical pathway for restoration and reconstruction of teeth in exposed zone guided by aesthetic analysis, and introduce the clinical process of aesthetic analysis and evaluation, the clinical triclassification of oral cosmetic restoration, and the corresponding clinical classification diagnosis and treatment points.

Influence of Abutment Screw-Tightening Methods on the Screw Joint: Immediate and Long-Term Stability.

Objective: To evaluate the influence of screw-tightening methods on the immediate and long-term stability of dental implant screw joints. Methodology. A total of 150 implants of three different implant systems with different diameters were used in this study. Each group was divided into three subgroups (n = 5), according to the tightening methods (A-tightening with recommended torque and retorque after 10 min; B-tightening with recommended torque, then loosening and immediate retorque; C-tightening with recommended torque only once). The operating time of tightening the assemblies was recorded. Ten minutes later, the immediate removal torque (IRT) (Ncm) was measured. After retightening the assemblies, a dynamic load between 20 and 200 N was applied for 105 cycles, and the postloading removal torque (PRT) (Ncm) was measured. Scanning electron microscopy (SEM) was used to observe the surface topography of the screws. Results: For different types of implants, the IRTs were 11.92 ± 1.04-34.12 ± 0.36 Ncm for method A, 11.64 ± 0.57-33.96 ± 0.29 Ncm for method B, and 10.30 ± 0.41-31.62 ± 0.52 Ncm for method C, and the IRTs of methods A and B were 6.28%-21.58% higher than that of method C (P ≤ 0.046). The PRTs were 4.08 ± 0.77-29.86 ± 0.65 Ncm for method A, 4.04 ± 0.40-29.60 ± 0.36 Ncm for method B, and 2.98 ± 0.26-26.38 ± 0.59 Ncm for method C, and the PRTs of methods A and B were 11.77%-44.87% higher than that of method C (P ≤ 0.016). The removal torque loss rates of methods A (12.49% ± 0.99%-65.88% ± 4.83%) and B (12.84% ± 0.96%-65.35% ± 1.95%) were 3.04%-7.74% lower than that of method C (16.58% ± 0.56%-71.10% ± 1.58%) (P ≤ 0.017). The operating time of method A was much longer than those of methods B and C (P < 0.001). The structural integrity disruption of the screw thread was observed according to the SEM results in all postloading groups. Conclusions: Method B (torquing and then loosening and immediate retorquing) increases the screw joint immediate stability by 6.28%-21.58% and the long-term stability by 11.77%-44.87% compared with method C (torquing only once), has comparable screw joint stability compared with method A (retorquing after 10 min), saves time and is recommended in clinical settings.

Enhancing cell adhesive and antibacterial activities of glass-fibre-reinforced polyetherketoneketone through Mg and Ag PIII.

Glass-fibre-reinforced polyetherketoneketone (PEKK-GF) shows great potential for application as a dental implant restoration material; however, its surface bioinertness and poor antibacterial properties limit its integration with peri-implant soft tissue, which is critical in the long-term success of implant restoration. Herein, functional magnesium (Mg) and silver (Ag) ions were introduced into PEKK-GF by plasma immersion ion implantation (PIII). Surface characterization confirmed that the surface morphology of PEKK-GF was not visibly affected by PIII treatment. Further tests revealed that PIII changed the wettability and electrochemical environment of the PEKK-GF surface and enabled the release of Mg2+ and Ag+ modulated by Giavanni effect. In vitro experiments showed that Mg/Ag PIII-treated PEKK-GF promoted the proliferation and adhesion of human gingival fibroblasts and upregulated the expression of adhesion-related genes and proteins. In addition, the treated samples inhibited the metabolic viability and adhesion of Streptococcus mutans and Porphyromonas gingivalis on their surfaces, distorting bacterial morphology. Mg/Ag PIII surface treatment improved the soft tissue integration and antibacterial activities of PEKK-GF, which will further support and broaden its adoption in dentistry.

Functionalized Cortical Bone-Inspired Composites Adapt to the Mechanical and Biological Properties of the Edentulous Area to Resist Fretting Wear.

Dental implants with long-term success of osseointegration have always been the goal, however, difficulties exist. The accumulation of fretting damage at the implant-bone interface often gets overlooked. Commonly used titanium is approximately 7-fold harder and stiffer than cortical bone. Stress shielding caused by the mismatching of the elastic modulus aggravates fretting at the interface, which is accompanied by the risk of the formation of proinflammatory metal debris and implant loosening. Thus, the authors explore functionalized cortical bone-inspired composites (FCBIC) with a hierarchical structure at multiple scales, that exhibit good mechanical and biological adaptivity with cortical bone. The design is inspired by nature, combining brittle minerals with organic molecules to maintain machinability, which helps to acquire excellent energy-dissipating capability. It therefore has the comparable hardness and elastic modulus, strength, and elastic-plastic deformation to cortical bone. Meanwhile, this cortical bone analogy exhibits excellent osteoinduction and osseointegration abilities. These two properties also facilitate each other to resist fretting wear, and therefore improve the success rate of implantation. Based on these results, the biological-mechanical co-operation coefficient is proposed to describe the coupling between these two factors for designing the optimized dental implants.

The mechanical properties, tribological behaviors and color stability of a feldspar nanoceramics strengthening extrinsic stain for high-translucent zirconia.

The present work is aimed to explore the mechanical properties, tribological behaviors and color stability of nanoceramics and microceramics strengthened extrinsic stain coatings (NS and MS) upon high-translucent zirconia (TZ). The Na-rich feldspar ceramics component, microstructure and particle size of NS and MS were verified. The mechanical properties including elastic modulus and hardness of NS were enhanced compared to MS. Reciprocating wear tests under a ball-on-plate configuration manifested that the reduced coefficient of friction, wear depth and wear volume loss of NS was evaluated after 1 × 10 4 cycles and the wear scar morphology of NS characterized by microcracks while MS featured more delamination and wear debris. Post toothbrushing simulation revealed that the color stability of extrinsic stain coatings was elevated with the addition of feldspar nanoceramics. The feldspar nanoceramics strengthening extrinsic stain exhibited enhanced elastic modulus, hardness, wear resistance and color stability, especially for TZ.

Guided removal of a fractured fiber post and immediate restoration with a digitally prefabricated titanium post-and-core and zirconia crown: A clinical report.

A completely digital workflow is described for the immediate restoration of a fractured fiber post with a digitally prefabricated definitive restoration using 3-dimensionally printed guides. The geometric morphology and axis of the root canal were digitally determined by using cone beam computed tomography to localize the 3-dimensional position of the fractured fiber post. A virtual drill modeled on the shape of the fractured post was fabricated and customized for removal of the post by using a guide to facilitate the intraoral transfer of the drilling procedure. A titanium post-and-core and crown had been virtually predesigned and fabricated before the procedure, and 2 digital guides were designed for their placement. All guides were 3-dimensionally printed. By following this workflow, the removal of the fractured fiber post and immediate definitive restoration were completed in 1 visit, facilitating a more efficient, predictable, and straightforward treatment.

Esthetic rehabilitation for a Kennedy Class IV patient using detachable 3D printing diagnostic denture and removable partial denture with polyetheretherketone framework.

For patients with high aesthetic expectation, using removable partial dentures (RPDs) to restore the missing teeth in the aesthetic area rapidly and obtain the patients' approval is challenging. This case described an alternative digital protocol to solve this situation. A detachable 3DP diagnostic denture was involved in the procedure, which not only allowed patient to evaluate the possible outcome of the RPD, but also can be duplicated to form a definitive RPD, by bonding a milled PEEK framework and a customized PMMA dentition containing posts, using a thermoplastic compression molding (CM)process.

Recording jaw relation of a pediatric patient with ectodermal dysplasia and complete anodontia using a digital mini arch tracer: A case report.

Children with ectodermal dysplasia and complete anodontia experience difficulties in oral rehabilitation because of the small arch size. A case of a 7-year-old boy, whose arch size (length and width) was 30-40% smaller than that of a male adult and who presented with difficulties in jaw relation recording using commercially available devices is described. A digital workflow involving a mini arch tracer was introduced. Primary impressions were made using three-dimensionally (3D) printed mini trays produced based on the patient's computed tomography images, and digital primary casts were obtained based on the scanned and reversed primary impressions. The final custom impression trays with mini tracing plates were designed based on the primary casts. In addition, the hand shank, retention plate, and retainers were placed on the designed custom trays and 3D-printed to produce an individual arch tracer system. In addition, two height-checking buckles were designed to help adjust the height of a tracing screw. Finally, the jaw relation of the patient was recorded and transferred, and a set of complete dentures were delivered, satisfying both the patient and his family.

Clinical decision-making of anterior implant abutment.

Abutment is an important component serving as a connecting link between the implant and the implant-supported prosthesis. In accordance with mechanical, biological, and other conventional norms, it can compensate the deviation between the implant and the prosthesis, which plays a significant role in maintaining the health of peri-implant tissue and the longevity, stability, and effectivity of prosthesis. However, choosing an anterior implant abutment correctly and conveniently is challenging, given the great variety of anterior abutment in clinical practice. Through virtual implant design, the correct implant site was compared and selected, and the supra-target prosthesis was coordinated before and after the operation. The implant level vertical of height of target restoration space (I) was measured to predict the availability and the retentive method of the implant restoration. After implantation, the primary selection of abutment type was selected according to the implant system (S), screw access position, and retentive method of the prosthesis. The final selection of abutment is accomplished by combining the measured values of peri-implant soft tissue thickness (T), gingival height (GH), and long axis of implant (L). Furthermore, the concepts and the classified applications of custom abutment were discussed in detail in this paper. The plan's main control variables L, I, GH, T, and S compose the words Lights, so this plan can be abbreviated as the anterior abutment decision tree. The decision tree has good decision-making efficiency and high clinical accessibility.

An investigation of the microstructure and mechanical properties of dental zirconia manufactured by digital light processing 3D printing.

OBJECTIVES: This study was performed to investigate the microstructure and mechanical properties of dental zirconia manufactured by digital light processing (DLP) 3D printing and the clinical application prospects of this material. METHODS: The experiment (DLP) group was zirconia manufactured by DLP 3D printing, and the control (MILL) group was milled zirconia. The density, grain size, and phase composition were measured to study the microstructure. Flexural strength was measured by using three-point bending tests, while Vickers hardness was determined through a Vickers hardness tester. Fracture toughness was tested using the single-edge V-notched beam method. RESULTS: Zirconia density of the DLP group was (6.019 8±0.021 3) g·cm-3, and the average grain size was (0.603 0±0.032 6) µm, but without statistical difference with the corresponding values of the MILL group (P>0.05). Tetragonal phase was found in the X-ray diffraction patterns of the DLP and MILL groups. The flexural strength of the DLP group was (1 012.7±125.5) MPa, and Vickers hardness was (1 238.5±10.8) HV1, which was slightly lower than that of the MILL group (P<0.05). The fracture toughness of the DLP group was (7.22±0.81) MPa·m1/2, which was not statistically different from that of the MILL group (P>0.05). CONCLUSIONS: Zirconia manufactured by DLP 3D printing had microstructure and mechanical properties similar to those of the milled zirconia. Only the flexural strength and the Vickers hardness of the experimental zirconia were slightly lower than those of the milled zirconia. Therefore, DLP-manufactured zirconia has a promising future for clinical use.

Corrigendum to "Determination of Hardness and Fracture Toughness of Y-TZP Manufactured by Digital Light Processing through the Indentation Technique".

[This corrects the article DOI: 10.1155/2021/6612840.].

Determination of Hardness and Fracture Toughness of Y-TZP Manufactured by Digital Light Processing through the Indentation Technique.

OBJECTIVE: The purpose of the study was to determine the hardness and fracture toughness of dental yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) manufactured by digital light processing (DLP) technology to study its clinical prospects. METHODS: The experimental group was DLP-manufactured zirconia, and the control group was milled zirconia. The hardness was investigated under a range of test loads (0.49 N, 0.98 N, 1.96 N, 4.90 N, 9.81 N, 29.42 N, 49.03 N, 98.07 N, and 196.1 N). Meyer's law was applied to describe the indentation size effect (ISE). Meanwhile, the PSR model and MPSR model were utilized to generate true hardness values. The cracks were observed to be induced by indentation under loads above 49.03 N, while the cracks showed the radial-median type under the load of 196.1 N, under which the fracture toughness was calculated. RESULTS: The true hardness of DLP-manufactured zirconia was 1189 HV based on the PSR model and 1193 HV based on the MPSR model, a bit lower than that of milled zirconia. The fracture toughness was 3.43 ± 0.29 MPa√m, which showed no statistical difference with the milled zirconia. CONCLUSION: The dental zirconia manufactured by the DLP 3D printing technique is similar to that manufactured by the conventional milling process in hardness and fracture toughness, thus having a promising future of clinical use.

[Research progress in the relationship between Veillonella and oral diseases].

Veillonella species, known as the early colonizer of oral biofilm, are prevalent in oral microbiota. Seven Veillonella species have been isolated from oral cavity. Their distribution varies not only with different people but also with different sites in the oral cavity. Oral Veillonella are associated with oral diseases. They contribute to the adhesion of Streptococcus mutans and consume the lactate generated by streptococci. Veillonella species play an important role in the occurrence and development of periodontal diseases by providing adhesion sites for Porphyromonas gingivalis and boosting immune responses. The production of lipopolysaccharide and H2S is related to other oral diseases, such as pulpitis, periapical periodontitis, and halitosis. Several studies have been conducted on the relationship between Veillonella and oral diseases and the interaction between Veillonella and other pathological microorganisms, but limited knowledge is available at the molecular level. This article reviews the research progress in the relationship between Veillonella and oral infectious diseases, such as dental caries and periodontal diseases.