Chinese Journal of Dental Research, 04/2021

Extracellular vesicles (EVs), produced by exocytosis or membrane budding of cells, are membranous vesicles that carry specific proteins, nucleic acids and other bioactive molecules. EVs are indispensable carriers of biological information and play a critical role in cell-to-cell communication. Due to their involvement in physiological and pathological processes, EVs have shown great potential in the diagnosis and treatment of various diseases in recent years. The present review focuses on the regulatory role of EVs in oral and craniofacial diseases to provide valuable insights into possible applications in translational medicine. Keywords: diagnosis, extracellular vesicles, oral diseases, therapy

Periodontitis is one of the severe oral diseases that threatens both the oral and general health of humans. It is an inflammatory disease caused by the complex interaction between the plaque microorganisms and the host immune system. The innate immune response is activated when pathogens invade the periodontium. An excessive innate immune response leads to inflammation and the destruction of periodontal tissues, which then activates the adaptive immune response. Although systemic initial therapy and guided tissue regeneration (GTR) can control periodontal inflammation to a certain extent and promote periodontal tissue regeneration, their effects are still limited. Periodontal treatment will be significantly improved if it is possible to screen the potential therapeutic targets and regulate the key molecules involved in periodontal disease; however, relevant research on the prevention and treatment of periodontitis remains limited. Thus, with the aim of assisting the immunoregulation of periodontitis, this article summarises the cells and mechanisms involved in the innate immune response and adaptive immune response caused by pathogens in the periodontium. Keywords: adaptive immune response immune cells, inflammation, innate immune response, periodontitis

The irradiance of powered polymerisation activators for chairside use affects composite resin adhesive curing during the restorative process, whereas radiant accumulated temperature rise relates to clinical safety. Irradiance reduction and high radiant accumulated temperature will compromise the treatment results as there is a lack of curing output efficacy and safety awareness for powered polymerisation activators. Insufficient attention has been paid to the activator’s quality control, irradiance attenuation and radiant accumulated temperature excessive temperature rise during its lifetime. The present manuscript has been drafted by the Society of Dental Equipment, Chinese Stomatological Association to fill the quality control gap and guide the quality control process, following tested steps, using a metered radiometer and a thermometer to record the irradiance and radiant accumulated temperature separately. The testing result may indicate the equipment’s situation in service and provide information about the irradiance values and performance of the powered polymerisation activator for its usage and maintenance. Keywords: dental powered polymerisation activator, quality control

Objective: To explore the effect of TRIB3 on the osteogenic differentiation of human adipose-derived mesenchymal stem cells (hASCs) and reveal the potential role of TRIB3 in bone regeneration. Methods: TRIB3-knockdown and TRIB3-overexpression hASCs were used to explore the effect of TRIB3 on osteogenic differentiation by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, quantitative real-time polymerase chain reaction (qRT-PCR) and heterotopic bone formation. The regulation of miR-24-3p on TRIB3 was detected by qRT-PCR and western blot. Ribonucleic acid (RNA) sequencing was performed to investigate the downstream regulatory network of TRIB3. Results: TRIB3 promoted the osteogenic differentiation of hASCs both in vitro and in vivo. This process was regulated epigenetically by the post-transcriptional regulation of miR-24-3p, which could bind directly to the three prime untranslated region (3’UTR) of TRIB3 and inhibit TRIB3 expression. The downstream regulatory network of TRIB3-mediated osteogenic differentiation was related to calcium ion binding and cell metabolism, extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and nuclear factor-κB (NF-κB) signalling pathways. Conclusion: TRIB3 is a promising therapeutic target for hASC-based bone tissue engineering and the epigenetic regulation of TRIB3 through miR-24-3p permits regulatory controllability, thus promoting osteogenesis through an important metabolic target while obtaining a safe and controllable effect via post-transcriptional epigenetic regulation. Keywords: epigenetic regulation, human adipose-derived mesenchymal stem cells, miR-24-3p, osteogenic differentiation, TRIB3

Objective: To assess bone volume stability and identify critical bone graft thickness for guided bone regeneration (GBR) simultaneous to implant placement in the maxillary anterior region. Methods: Eighteen patients were included in the study and received placement of one maxillary anterior implant combined with GBR using deproteinised bovine bone mineral (DBBM) and resorbable collagen membrane. The multilevel buccal bone thickness (BT) was measured by CBCT 1 to 2 weeks and 5 to 8 months post-implantation (at implant uncovering surgery). Results: Significant buccal alveolar crest collapse (ACCb 1.20 to 1.70 mm) occurred during the mean healing period of 5.3 months (P = 0.000). A greater percentage of ACCb occurred at the coronal aspect of the implant, with 59.24% ± 19.22% at the implant platform and 34.10% ± 30.50% 6.0 mm below the implant platform, respectively. Linear regression analysis demonstrated that if BT was 1.8 to 2.0 mm at the implant platform at uncovering surgery, then it was estimated to have been 4.1 to 4.5 mm immediately post-implantation. Conclusion: ACCb after maxillary anterior implant placement with simultaneous GBR occurred more coronally than apically. Excessive alveolar ridge augmentation, up to 4.0 mm of hard tissue buccal to the implant platform, should be achieved at the time of surgery to compensate for this potential resorption. Keywords: alveolar ridge augmentation, bone regeneration, bone substitute, CBCT, dental implants

Objective: To investigate the time efficiency of prefabricated prostheses located by an anchor pin stereolithographic attachment system for immediate loading implant reconstruction of completely edentulous jaws and compare it with the conventional protocol. Methods: Edentulous patients were recruited and randomly assigned into two groups: the full digital workflow group (digital group) and the conventional workflow group (conventional group). In the digital group, a provisional prosthesis was fabricated before surgery using a fully digital workflow and delivered immediately after implant placement. The positioning of the provisional prosthesis was guided precisely by the anchor pin attachment system. In the conventional group, the provisional prosthesis was fabricated after implant placement using a conventional procedure. Clinical and laboratory time efficiency were recorded, and clinician and patient satisfaction were evaluated. Results: Six patients were enrolled in this pilot study and 57 implants were placed following the guided surgery protocol. Of these, 54 were immediately loaded. The total clinical chair time in the digital workflow group was significantly less than that in the conventional workflow group (digital 60.0 ± 13.2 minutes; conventional 106.7 ± 24.7 minutes) (P = 0.045). The total post-surgery procedure took significantly less time in the digital group than the conventional group (digital 202.5 ± 22.5 minutes; conventional 403.7 ± 55.4 minutes) (P = 0.004). The patients’ and clinicians’ satisfaction with the provisional prostheses was similar in both groups. Conclusion: Time efficiency in immediate loading of implant-supported full-arch fixed restorations was improved with prefabricated prostheses located by the anchor-pin-attachment system. Less postoperative chair time was required in the digital group than in the conventional group. Keywords: edentulous, guided implant surgery, immediate loading, time efficiency

Objective: To investigate the effects of dental anxiety on fluctuations in blood pressure (BP) and heart rate (HR) during tooth extraction in hypertensive patients under local anaesthesia, and how they are influenced by various confounding variables. Methods: This is a prospective repeated-measures cohort study involving 600 patients successively recruited from Peking University School and Hospital of Stomatology, Beijing, China. BP and HR were repeatedly measured at rest (T0), before anaesthesia (T1), during tooth extraction (T2) and after tooth extraction (T3). Anxiety status was measured prior to local anaesthesia using a modified dental anxiety scale (MDAS). Three groups were assigned: mild anxiety (Corah DAS score of 4 to 8), moderate anxiety (score of 9 to 12) and severe anxiety (score of 13 to 20). We used a generalised linear mixed model (GLMM) to analyse the effects of dental anxiety on fluctuations in BP and HR. Interaction analysis was used to further explore the correlationship between these interactive factors. Results: The mean anxiety scale score was 9.63 ± 2.88. Severe preoperative anxiety (score of 14 to 20) was associated with significantly increased HR during administration of anaesthesia. Patients with severe anxiety also displayed a significantly greater increase in HR during anaesthetic administration (P < 0.001). When analysing the joint effects of different anxiety statuses over time, blood pressure was significantly elevated in all patients with moderate and severe anxiety during tooth extraction at T2 (β = 1.25, 95% CI 0.24 to 2.27). We also observed a significant decrease in HR in the moderate anxiety group at T3 (β = −1.51, 95% CI −2.38 to −0.63) and a significant increase in HR in the severe anxiety group at T1, T2 and T3 (β = 2.52, 95% CI 1.12 to 3.93; β = 3.84, 95% CI 2.30 to 5.38; β = 4.57, 95% CI 3.03 to 6.11, respectively). Conclusion: This study indicates that the effects of dental anxiety on BP and HR in middle-aged and elderly patients with hypertension during local anaesthesia and tooth extraction were influenced by various confounding variables. Keywords: blood pressure, dental anxiety, extraction, heart rate, hypertension

Objective: To evaluate and compare the crown preparation performance of preclinical dental students training with conventional composite resin teeth and newly developed double-layer composite resin teeth. Methods: The newly developed composite resin teeth consisted of two layers with different colours and hardnesses. Twenty third-year undergraduate dental students (8 men, 12 women) were randomly assigned to the control group (Group 1, using conventional composite resin teeth; n = 10) or the experimental group (Group 2, using double-layer composite resin teeth; n = 10) to prepare metal-ceramic crowns. To practice, each student prepared one tooth per day for 2 days. For the baseline test and final test before and after the practice period, both groups used traditional teeth. The operation time was recorded and the prepared teeth were scored blindly by two experienced instructors. The time and scores were compared within and between groups to determine the difference (α = 0.05). Results: Students in both groups spent less time (P < 0.05) and achieved better scores (P < 0.001) on the final test than the baseline test (P < 0.01). In the final test, no significant difference in operating time was found between the two groups (P > 0.05), but Group 2 yielded significantly higher scores (P < 0.05). Conclusion: Training with the double-layer composite resin teeth enabled students to progress more quickly in terms of operating time and achieve higher scores. Use of this newly-developed tooth in crown preparation teaching practice therefore yields highly promising results. Keywords: 3D printing, computer simulation, milling, prosthodontics, teaching methods, tooth preparation