The growing demand for charming smiles has led to the popularization of tooth bleaching procedures. Current tooth bleaching products with high-concentration hydrogen peroxide (HP, 30–40%) are effective but detrimental due to the increased risk of enamel destruction, tooth sensitivity, and gingival irritation. Herein, we reported a less-destructive and efficient tooth whitening strategy with a low-concentration HP, which was realized by the remarkably enhanced Fenton-like catalytic activity of oxygen-deficient TiO2 (TiO2–x ). TiO2–x nanoparticles were synthesized with a modified solid-state chemical reduction approach with NaBH4. The Fenton-like activity of TiO2–x was optimized by manipulating oxygen vacancy (OV) concentration and further promoted by the near-infrared (NIR)-induced photothermal effect of TiO2–x . The TiO2–x sample named BT45 was chosen due to the highest methylene blue (MB) adsorption ability and Fenton-like activity among acquired samples. The photothermal property of BT45 under 808 nm NIR irradiation was verified and its enhancement on Fenton-like activity was also studied. The BT45/HP + NIR group performed significantly better in tooth whitening than the HP + NIR group on various discolored teeth (stained by Orange II, tea, or rhodamine B). Excitingly, the same tooth whitening performance as the Opalescence Boost, a tooth bleaching product containing 40% HP, was obtained by a self-produced bleaching gel based on this novel system containing 12% HP. Besides, negligible enamel destruction, safe temperature range, and good cytocompatibility of TiO2–x nanoparticles also demonstrated the safety of this tooth bleaching strategy. This work indicated that the photothermal-enhanced Fenton-like performance of the TiO2–x -based system is highly promising in tooth bleaching application and can also be extended to other biomedical applications.

Objectives: To assess the efficacy of topical sialogogue spray containing malic acid 1% for treating xerostomia. Methods: We searched PubMed, Cochrane Library, Embase, ClinicalTrials.gov and Web of Science databases. Literature search, screening, study selection, data collection, data extraction and assessment of bias risk were independently conducted by two reviewers. The study appraisal was performed by Cochrane Collaboration's tool for assessing bias risk. The systematic review registration number was PROSPERO-CRD42021241322. All statistical analyses were performed using Review Manager version 5.4. Results:Five original articles involving 244 patients with xerostomia who received topical sialogogue spray (malic acid 1%) or placebo for two weeks were included in this review. Based on the questionnaire survey, the topical sialogogue spray (malic acid 1%) improved the symptoms of dry mouth significantly better than the placebo, which was reflected in the Dry Mouth Questionnaire (DMQ), Xerostomia Inventory (XI) and Visual Analogue Scale (VAS) scores. Regarding the increase in unstimulated and stimulated saliva flow rates, the intervention group was also better than the placebo group after a two-week course of treatment. Conclusions:Although the included studies are limited, our results show that topical sialogogue spray (malic acid 1%) is an effective method for the treatment of xerostomia. Additional randomised controlled trials in the future are needed to provide highquality evidence of this therapy and to improve clinical practice guidelines.

The effective treatment for periodontitis is to completely and sustainedly eradicate the bacterial pathogens from the complex periodontal pockets. Local sustained-release antibiotics as a complementary treatment after scaling and root planning can sustainedly combat bacterial pathogens in the periodontal pockets to help treat the disease, but the increasing concern of bacterial resistance limits its future use. Here, we reported a local antibacterial system based on microsized multifunctional Ag−TiO 2−x encapsulated in alginate (ATA) microspheres. We confirmed that ATA displayed strong photothermally enhanced dual enzyme-mimicking (peroxidase-like and catalase-like) activities and weak photocatalytic activity under 808 nm near-infrared (NIR) irradiation, which could boost the generation of reactive oxygen species (ROS) and O 2 in the presence of low-level H 2 O 2 . As a result, the ATA/H 2 O 2 /NIR system exhibited efficient antibacterial activity against Porphyromonas gingivalis and Streptococcus gordonii in both planktonic and biofilm forms. With the help of ROS, ATA could release Ag + in concentrations sufficient to inhibit periodontal pathogens as well. Moreover, the in situ-generated oxygen was supposed to alleviate the local hypoxic environment and would help downregulate the lipopolysaccharide-mediated inflammatory response of periodontal stem cells. The in vivo rat periodontitis treatment results demonstrated that the ATA/H 2 O 2 /NIR system reduced the bacterial load, relieved inflammation, and improved tissue healing. Our work developed a new local prolonged bactericidal and oxygenation system for enhanced periodontitis. Avoiding the usage of antibiotics and nanomaterials, this strategy showed great promise in adjunctive periodontitis treatment and also in other biomedical applications.

No abstract

Hypoxia‐inducible factors (HIFs) are core regulators of the hypoxia response. HIF signaling is activated in the local physiological and pathological hypoxic environment, acting on downstream target genes to synthesize the corresponding proteins and regulate the hypoxic stress response. HIFs belong to the hypoxia‐activated transcription family and contain two heterodimeric transcription factors, HIF‐α and HIF‐β. Under hypoxia, the dimer formed by HIF‐α binding to HIF‐β translocates into the nucleus and binds to the hypoxia response element (HRE) to induce transcription of a series of genes. HIF‐1α plays an important role in innate bone development and acquired bone regeneration. HIF‐1α promotes bone regeneration mainly through the following two pathways: (1) By regulating angiogenesis‐osteoblast coupling to promote bone regeneration; and (2) by inducing metabolic reprogramming in osteoblasts, promoting cellular anaerobic glycolysis, ensuring the energy supply of osteoblasts under hypoxic conditions, and further promoting bone regeneration and repair. This article reviews recent basic research on HIF‐1α and its role in promoting osteogenesis, discusses the possible molecular mechanisms, introduces the hypoxia‐independent role of HIF‐1α and reviews the application prospects of HIF‐1α in tissue engineering.