Digital economy plays an irreplaceable role in achieving energy development, and may also have a profound impact on energy supply and consumption. Based on a panel dataset of 30 provinces in China for the period 2006 to 2019, we assess the impact of digital economy on energy trilemma. This study also detects the asymmetric nexus between digital economy and energy trilemma, and investigates the direct and indirect effects of digital economy on energy trilemma. The main findings are as follows. (1) Digital economy shows a significant inhibitory effect on energy trilemma, which means energy trilemma can be effectively eradicated by promoting the development of digital economy. (2) Digital economy has a more prominent inhibitory effect on energy trilemma when the latter is at lower quantiles, and the marginal impact of digital economy on the energy trilemma decreases as the level of energy trilemma increases. (3) Digital economy exerts a significant and negative impact on energy insecurity, inequity, and unsustainability, which are three pillars of the energy trilemma. (4) Digital economy contributes to the eradication of energy trilemma by inhibiting traditional energy consumption and simultaneously encouraging technology innovation, which are two mediators in the nexus between digital economy and energy trilemma. Following the above findings, this study presents a series of policy recommendations for accelerating the development of digital economy and restricting energy trilemma.

OBJECTIVE: This case report presents a direct composite inverse injection technique using a bi-layer clear mini-index fabricated with a digital workflow to restore extensive posterior occlusal cavities in a 13-year-old patient.
METHODS: After a root canal treatment in the right mandibular first molar and step-wise excavation of deep caries in the left mandibular first molar, the extensive occlusal restorations were digitally designed using CAD software, upon which digital wax-ups were 3D-printed. Bi-layer clear mini-indices consisting of a hard outer plastic layer and an elastic inner silicone layer were prepared from the 3D-printed cast. The bonding surfaces were deproteinized using a 6% sodium hypochlorite solution, and an antioxidant (Clearfil DC Activator; Kuraray Noritake) was utilized to improve the dentin bonding durability of a 2-step self-etch adhesive (Clearfil SE Bond 2; Kuraray Noritake). Subsequently, a highly filled universal-shade flowable resin composite (RC) was incrementally placed into the cavities. To create the final occlusal morphology, the same RC was inversely injected through the opening of the bi-layer indices.
RESULTS: The workflow was feasible, and the occlusal cavities were efficiently restored using the injection technique. Occlusal carving and adjustments of the morphology were not necessary, leading to less chair time. At the 1-year follow-up, the clinical outcome was excellent.
CONCLUSIONS: The injection technique with a bi-layer clear mini-index accurately translated the digital wax-ups into large, final restorations. Precise morphology and shortened chair time enhanced patient satisfaction, but at the expense of multiple visits.

Two fractured maxillary central incisors were restored via the crown fragment reattachment technique with adhesive systems and composite resin material. A long-term successful outcome was achieved after 4 years of follow-up. The patient presented with fractured maxillary central incisors, and a comprehensive intraoral and radiographic examination revealed that both teeth had extended crown fractures with no pulpal exposure (Class II, Ellis and Davey). The tooth fragments were thoroughly cleaned and inspected before being repositioned. Both fragments were in excellent condition with almost no pieces missing. Therefore, the proposed treatment was fragment reattachment. After verifying the repositioning and adaptation of the fractured fragments, a flowable composite was used to perform the reattachment procedure under rubber dam isolation. With modern dental adhesives, the reattachment of tooth fragments in good condition is considered a more conservative option for restoring tooth morphology, esthetics, and function. Although one tooth showed signs of irreversible pulpitis and required root canal treatment 2 weeks after the restoration, the clinical and radiographic evaluations at the 4-year follow-up visits confirmed the success of the restorative treatment. The restorations showed good functional and esthetic outcomes after 4 years of follow-up.

Many authors have advocated retentive tooth preparations for resin composite restorations intended to halt progression of incisal edge attrition with worn concave dentin, probably due to frustration with adhesive restorations being lost from these defects. Unfortunately, this technique further removes the dentin these restorations are intended to preserve. The purpose of this article is to demonstrate a purely adhesive, less invasive technique for restoration of worn concave incisal edges, which includes air particle abrasion and increased etching time for the sclerotic dentin and unprepared enamel. Favorable two-year results for mandibular anterior teeth opposed by natural teeth are reported.

Prefabricated glass fiber-reinforced composite posts have been widely used because of their esthetic properties and favorable biomechanical behavior; however, because they are prefabricated, they may not adapt to the anatomy of all root canals. This case report describes a procedure for restoring teeth with a custom, 1-piece, fiber-reinforced composite post and core fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM). The excellent adaptation of this custom endodontic post enables the use of a thinner, homogenous cement layer; in addition, it eliminates the need to construct a composite resin core build-up. Although more clinical and in vitro studies are needed to better define the appropriate clinical protocols and assess various materials, CAD/CAM technology allows post and core restorations to be manufactured in a predictable and simplified way.

The two-step approach of applying hydrofluoric acid followed by silane is deemed the gold-standard surface treatment protocol before bonding to glass ceramics. Given hydrofluoric acid is a toxic conditioning agent and with the intention to simplify this step, the dental company Ivoclar Vivadent (Schaan, Lietchtenstein) released a self-etching ceramic primer, Monobond Etch & Prime in 2015, claiming that hydrofluoric acid and silane application would no longer be required prior to luting glass ceramics. Therefore, this clinical case report and retrospective analysis describes the replacement of unsatisfactory anterior veneers due to clinical failures for new feldspathic glass ceramic veneers, using the aforementioned self-etching ceramic primer. After two years, feldspathic glass ceramics presented satisfying clinical performance with absence of debonding, tooth sensitivity, recurrent carious lesions, or marginal infiltration.

For restoring extensive cavities in severely damaged or decayed posterior teeth, especially those with thin walls, indirect restorations are recommended rather than direct fillings. Regarding indirect restorations for inlays and onlays, composite resin-based CAD/CAM materials are considered to have several advantages over ceramics such as easy manufacturing, lower cost, and simpler repairability. A case is presented in this article in which the treatment plan and protocol combine multiple evidence-based clinical techniques such as immediate dentin sealing (IDS), cavity design optimization (CDO), and cervical margin relocation (CMR). For CDO and CMR, two different types of flowable composite resins with different viscosities were used. Restoring such extensively damaged teeth using a defect-oriented adhesive technique is considered a challenge both in terms of the preservation of healthy tooth structure and the proper isolation for adhesive luting. The IDS technique was used to enhance the bonding to the remaining dentin, while CDO was performed to avoid unnecessary removal of vital tooth structure, for example, undercuts. The deep subgingival margins were elevated using the CMR technique to facilitate the impression taking and a contamination-free luting of the final restoration. Combining the aforementioned techniques enabled a defect-oriented, minimally invasive restoration of a severely decayed tooth. The aim of this article is to present those techniques in a simplified way through a clinical case as a step-by-step guide for the practitioner.

Enduring glass-ceramic restorations greatly depend on the quality of adhesion of the crown to enamel and dentin. Proper isolation is vital to the success of bonded ceramic restorations. The rubber dam has long been considered the primary method of preventing contamination of the operating field, a crucial requisite for adhesion. However, many dentists do not use rubber dam isolation due to its penchant for slowing down procedures. The authors present a case report that describes a technique for the indirect bonding of a ceramic restoration to a maxillary first molar using rubber dam isolation in conjunction with a floss ligature,a method that is aimed at optimizing operator effectiveness and efficiency.

Treatment of a large proximal carious lesion that extends below the cementoenamel junction is challenging. Large defects usually require replacement with indirect restorations (inlays, onlays, or crowns). However, when the gingival cavity margins are deep, procedures such as isolation of the operative field, proper cavity preparation, successful impression-making, and adhesive luting may be hindered unless soft gingival or hard bony tissues are removed to expose the cavity margin. The present case report describes the clinical application of a conservative cervical margin relocation technique for treating deep cavity margins. A patient presented with large distal carious lesions and necrotic pulps in both the maxillary and mandibular right first molars, which were diagnosed with symptomatic apical periodontitis. After root canal treatment of both teeth, the maxillary molar underwent a crown-lengthening surgical procedure and subsequent placement of a zirconia crown. In the mandibular molar, the cervical margin was relocated by placing a composite resin base at the proximal gingival cavity margins under meticulous isolation of the operative field. The tooth was restored with a composite core build-up and bonded ceramic onlay. The satisfactory outcome suggested a promising prognosis for the oral health of the patient.

The aim of this study was to use polyetheretherketone (PEEK) for the post material and evaluate the fracture load of six restoration patterns in teeth with flared root canals; composite resin core alone (Group R); glass fiber sleeve (Group S); PEEK post (Group P); glass fiber post (Group F); PEEK post in glass fiber sleeve (Group PS); glass fiber post in glass fiber sleeve (Group FS). In this study, cylindroid specimens were prepared and underwent three-point-bending test in a steady condition and after water immersion. In the loading test, the materials in clinical conditions using bovine teeth were evaluated. In the bending test, groups using glass fiber posts and sleeves decreased in strength after water immersion. In the loading test, Groups F, FS and PS showed higher fracture load than other groups. This study showed PEEK posts and glass fiber sleeves are recommended in the case of flared root canals.