With the arrival of the era of big data, increasing attention has been drawn to the application of artificial intelligence (AI) in the medical field. AI has many advantages, such as objectivity, accuracy, minimal invasiveness, time savings and high efficiency. Therefore, the combination of AI with dental diagnosis and treatment can help dentists improve work efficiency and save medical resources, offering potential significant benefits for dental application. At present, AI has been gradually integrated into prosthodontics, oral and maxillofacial surgery, orthodontics, endodontics and periodontics. The AI system can realize automatic tooth preparation, automatic tooth arrangement and implantology. Deep learning can be used to assist in diagnosing maxillary sinus inflammation, predicting the complications of tooth extraction and improving the accuracy of osteotomy. The AI system can also provide significant clues for the diagnosis, treatment and prognosis of oral and maxillofacial tumors. The breakthrough brought by AI in cephalometric and the assessment of facial attractiveness of patients has promoted the development of intelligent and personalized orthodontic treatment. Deep learning and analysis of medical images also promote the accuracy of root canal therapy as well as the diagnosis and treatment of periodontal diseases. AI technology has realized the leap from digitalization to automation and intelligence in oral diagnosis and treatment, and its application potential in the oral field should not be underestimated. Based on the concepts of AI, this paper will focus on the application of artificial intelligence in various oral clinical fields and briefly introduce its advantages, problems and future.

Ectopic eruption of the first permanent molar is a common malocclusion in the early stage of mixed dentition. The incidence among children aged 6-10 years is 0.83%-8.7%, with an increasing trend. The main manifestation is mesial impaction of the first permanent molar during eruption, which is accompanied by the loss of root resorption and space loss of the second primary molar. Ectopic eruption of the first permanent molars can lead to underdevelopment of the dental arch and severe crowding of the posterior dentition. Prevention and early intervention are very important. The ectopic eruption of the first permanent molar is related to the disruption of the differential growth and developmental balance among the teeth, alveolar bone and jaw. In clinical practice, the diagnosis can be made according to the patient's medical history and clinical and imaging examinations, and the treatment can be performed by dividing the teeth, dividing the distal slices of the second primary molars, and distally moving the first permanent molars. This paper reviews the incidence, etiology, clinical manifestations, risks of ectopic eruption of the first permanent molar, diagnostic methods, and common treatment options to provide references for clinical treatment.

Exosomes are phospholipid bilayer vesicles secreted by living cells that can carry a variety of signaling molecules, such as RNA, DNA, protein, and lipids. Exosomes play a role in the transmission of signaling molecules between cells, thus regulating many physiological and pathological processes. The methods of extracting exosomes include differential centrifugation, density gradient centrifugation, exclusion chromatography, ultrafiltration, coprecipitation, polymer immune affinity, microfluidic separation technology, etc. Each of these extraction technologies has advantages and disadvantages; however, there is no unified international standard. In addition, the expression of specific proteins and genetic material of exosomes from different cell sources are different; thus, their expression characteristics and functions are also distinctive. Based on this situation, research on exosomes is limited to preclinical studies, and difficulties and challenges still exist in clinical application. This paper summarizes the progress of research in the field of exosomes, to understand the characteristics, modification and application of exosomes from different cell sources, and to summarize their advantages and disadvantages as well as challenges, which can help researchers better understand and master the performance of exosomes. Furthermore, improvement of standard procedures in the extraction and manufacturing of exosomes is important, as it will provide a reference for researchers to carry out exosome-related translational clinical research.

The most common periodontal biotype in the Chinese population is thin, which obviously limits orthodontic tooth movement. Periodontally accelerated osteogenic orthodontics (PAOO) can not only accelerate tooth movement through corticotomy but also expand the range of orthodontic tooth movement by alveolar bone augmentation, which could reduce the periodontal complications of orthodontic therapy. The development of PAOO has gone through a long and tortuous historical process over more than 100 years: from osteotomy based on "bony block movement" at the beginning to cortical osteotomy based on "the regional acceleratory phenomenon" and then to PAOO based on "bone tissue engineering". Throughout its development history, the understanding of the biological basis determines the development of the clinical technology. Therefore, PAOO should be based on basic research. Both the present clinical practice and future surgical improvements should be based on the fundamentals of bone repair and regeneration. According to the current evidence, it is suggested that piezocision and laser-assisted flapless corticotomy should be chosen only for simple cortical osteotomy, and surgical navigation technology or 3D-printed surgical guides are recommended. When a large amount of bone augmentation is needed, PAOO with an intact flap is still the first choice. A stable and infection-free healing environment is the key to wound healing; therefore, in addition to infection control, the surgical area should also be protected from external forces. At present, there are few high-quality clinical studies on PAOO. Multicenter, large-sample, randomized controlled clinical trials are needed to evaluate the clinical efficacy of different PAOO techniques in the future. The present article introduces the development history, fundamentals and operation precautions of PAOO, and a new perspective is also proposed, which may provide a reference for clinical practice.

Impacted teeth are a kind of complex malocclusion, and their incidence differs among different races, sexes and dental positions. The causes of impacted teeth include systemic factors and local factors, such as endocrine disorders, malnutrition, and acute and chronic infectious diseases. Local factors can cause abnormal tooth development or eruption during the process from tooth development to tooth eruption, such as damaged permanent tooth embryos caused by local inflammation or trauma, insufficient eruption space caused by premature loss of deciduous teeth, and eruption disorders caused by local lesions for example hyperplasia or odontoma. The clinical manifestation of impacted teeth is the absence of a permanent tooth in a normal position. We can use cone beam CT (CBCT) to locate the impacted teeth. Comprehensive orthodontic treatment includes surgical-assisted eruption, extraction of retained deciduous teeth or supernumerary teeth, removal of lesions such as odontomas and cysts, and expansion of the orthodontic space. When the dysfunctional local soft and hard tissues are removed during a surgical operation, the tooth still cannot sprout smoothly, and it needs to be assisted by orthodontic traction-guided eruption or extracted and autotransplantation. A clear diagnosis, evaluation of the difficulty of treatment and appropriate treatment are the keys to improving the success rate of treatment. In this paper, the epidemiology, etiology, diagnosis and corresponding treatment methods of impacted teeth will be reviewed, and the orthodontic treatment of impacted teeth will be comprehensively described to provide a reference for clinicians about the treatment of impacted teeth.

Curcumin is a natural medicine with a wide range of sources and low toxicity. It has antibacterial, antifungal, anti-inflammatory and other pharmacological effects. In recent years, curcumin has attracted much attention in the field of prevention and treatment of oral infectious diseases. Single curcumin is easily degraded during application and has poor water solubility and low bioavailability, but it can be used as a natural photosensitizer to mediate photodynamic treatment of oral infections. Photodynamic therapy has high antibacterial efficiency and can better protect the appearance and function of the affected area. This article reviews the research on curcumin-mediated photodynamic therapy for oral infectious diseases. As a natural photosensitizer, curcumin mediates photodynamic therapy and has shown good therapeutic effects against dental caries, endodontics, periodontitis, oral candidiasis and other oral infectious diseases by enhancing antibacterial ability, increasing the production of reactive oxygen species, and inhibiting the formation of biofilms. In-depth exploration of the mechanism of action of curcumin-mediated photodynamic therapy in different oral infectious diseases can provide new strategies for the prevention and treatment of oral infectious diseases.

Corona Virus Disease 2019 (Corona Virus Disease 2019,COVID-19) has become a public health emergency that has attracted global attention because of its large-scale outbreak resulting in numerous human infections and deaths. COVID-19 is a highly contagious respiratory disease caused by novel coronavirus 2019-nCoV. Due to a large number of infections and fast transmission speed, it's significant to diagnose the infected people quickly and detect the asymptomatic infected people as soon as possible. At present, the preliminary screening is judged by the clinical manifestations of the patients, mainly involving the respiratory system, but recent studies have found that the patients infected with COVID-19 have unique oral manifestations, such as taste disturbance, xerostomia, halitosis, inflammation of salivary glands, necrotizing periodontal disease and some of them are earlier than typical symptoms such as dry cough, fever, etc. Paying attention to the oral manifestations of patients can further improve the COVID-19 screening procedure. At present, symptomatic treatment is mainly used for these oral symptoms.

Regenerative endodontic procedures, based on dental pulp biology, use the basic principles of tissue engineering to promote the functional regeneration of dental pulp-dentin complexes. Good results have been achieved in the treatment of young permanent teeth with pulp necrosis or apical periodontitis. There have also been preliminary clinical explorations of the treatment of mature permanent teeth in recent years. The key to successful treatment is controlling infection as well as promoting tissue repair and regeneration. Moderate root canal mechanical preparation is allowed in the therapy of mature permanent teeth, while it is not recommended in the treatment of young permanent teeth. The choice of root canal irrigation and intracanal antisepsis requires a comprehensive consideration of the antibacterial effects, biological safety, and possible complications, such as crown discoloration and root canal calcification. The development of bioceramic materials provides more options for crown sealing materials, but further clinical evaluation is needed. In addition to traditional blood clot scaffolds, new types of tissue scaffolds represented by platelet-rich plasma, platelet-rich fibrin, concentrated growth factors and other platelet concentrates have been developed. Long-term and large-scale studies are needed to evaluate the actual clinical efficacy of these new scaffolds and the efficacy of their combined application with blood clots.

Benign tumors of the parotid gland are common tumors of the head and neck. Surgical resection is considered the main treatment. For the treatment of benign parotid tumors, different surgical approaches can be applied based on many factors, such as tumor type, size, location, depth of tumor and patient requirements, such as improved periauricular incision and improved facial wrinkle removal incision, to achieve the best therapeutic effect. In parotidectomy, the facial nerve, great auricular nerve and parotid duct should be protected as much as possible to preserve the function of the nerve and gland and reduce postoperative complications. In addition, complications after parotidectomy, such as facial nerve injury, salivary fistula, Frey syndrome, postoperative facial depression, abnormal ear sensation and recurrence, should be actively prevented and treated early after the operation, consequently minimizing the impact on patients' postoperative life and improving patients' satisfaction with the operation.

Dental anxiety refers to the unique tension, worry and even fear of dental treatment, which may lead to patients refusing to receive treatment and missing the best time for treatment. With the development of bio-psycho-social medical models, psychotherapy has gradually become the optimal treatment for dental anxiety. This article reviewed the etiology, evaluation and psychotherapy of dental anxiety. Research has shown that uncomfortable dental treatment experience is the main cause of dental anxiety, which is commonly assessed using questionnaires in clinical practice. Psychotherapy for dental anxiety is a noninvasive, widely applicable treatment without side effects, mainly including improving the treatment environment and service attitude, behavior therapy, and cognitive therapy, which has been shown to effectively alleviate dental anxiety in patients. However, psychotherapy for dental anxiety is highly demanding for dentists, which hinders its promotion and application. At the same time, the psychotherapeutic mechanism of dental anxiety is not clear and remains to be further elucidated by large-scale and high-quality randomized controlled studies.

In orthodontic and orthognathic practice, cephalometric analysis is an integral tool throughout the clinical process. However, as landmark identification is still unautomated, both the conventional and semiautomated approaches are open to considerable subjectivity and could be time-consuming for inexperienced clinicians. Deep learning (DL), a state-of-the-art artificial intelligence (AI) technique, is highly effective in image recognition. In recent years, many studies have focused on the application of DL in cephalometric analysis, including automated landmark detection, automated diagnosis, cervical vertebral maturation stage determination, adenoid hypertrophy analysis and upper airway identification. Studies show that DL can effectively improve the efficiency of cephalometric analysis. In most studies, the accuracy of DL can reach more than 80%, and its difference from the gold standard is clinically acceptable, demonstrating good potential for future applications. However, most studies are limited to landmark detection, and the broadness and richness of the training dataset are limited. Future studies should broaden the research scope, improve the algorithm, elevate the richness of the datasets, and combine DL with other AI algorithms to improve its accuracy, stability and generalizability.

In recent years, the application of artificial intelligence (AI) in the medical field, especially in dental imaging diagnosis, has developed rapidly. This review introduces research on AI in detail from the aspects of identifying caries, periapical lesions, vertical root fracture, periodontitis, maxillary supernumerary teeth and impacted mandibular third molars, oral and maxillofacial cystic lesions and temporomandibular joint disorders. Studies have shown that the diagnostic accuracy of AI in the abovementioned oral diseases is equivalent to or even better than that of dentists, indicating that AI has potential in oral disease diagnosis. However, AI models are limited by manual annotation accuracy, poor interpretability, weak generalization ability and difficulty in incremental learning. Future investigations should focus on the development and training of algorithms to improve AI accuracy in oral disease diagnosis.

Objective Metagenomic sequencing was used to explore the species composition and internal functional metabolic pathway of saliva and supragingival plaque microbial communities in healthy adults to provide a theoretical reference for the biological prevention and treatment of oral diseases. Methods Saliva and supragingival plaque samples were collected from healthy adults, total DNA was extracted, and a metagenomic library was constructed. The qualified library was sequenced via metagenomics, and the sequencing data were analyzed using bioinformatics and statistics. Results The main bacterial phyla in healthy oral samples were Proteobacteria (32.51%), Bacteroidetes (30.81%), and Actinobacteria (16.23%), and the main bacterial species were Corynebacterium matruchotii (3.84%), Haemophilus parainfluenzae (2.91%), and Prevotella melaninogenica (2.76%). The alpha diversity of the supragingival plaque group was higher than that of the saliva group, and there was a significant difference in the composition of the microbial community between the two groups (P<0.05). At the species level, Prevotella melaninogenica, Fusobacterium periodonticum, and Prevotella intermedia were more abundant in saliva samples than in supragingival plaque samples, while Corynebacterium matruchotii, Propionibacterium acidifaciens, and Rothia dentocariosa were more abundant in supragingival plaque samples than in saliva samples (P<0.05). High-quality gene sets of saliva and supragingival plaque in healthy adults were constructed based on metagenomic sequencing. The results of KEGG pathway functional metabolic differences showed that starch and sucrose metabolism, leucine and isoleucine degradation, and arginine biosynthesis in salivary microorganisms were more abundant than in supragingival plaque, while glycolysis/gluconeogenesis and carbon metabolism in supragingival plaque were more abundant than in saliva. Conclusion There are significant differences in the species composition and functional gene metabolic pathways of saliva and supragingival plaque microecology in healthy adults. The sensitivity of dominant species in different microecological regions to the identification of oral diseases may be different. In the microbiological study of oral diseases, appropriate samples should be selected according to different diseases.

Objective To explore the effects of long noncoding-RNA (lncRNA) taurine upregulated gene 1 (TUG1) on the proliferation and osteogenic/odontoblast differentiation of human dental pulp stem cells (hDPSCs). Methods hDPSCs were isolated and cultured. The surface antigens CD44, CD45, CD73, CD90, CD133 and STRO-1 were detected by flow cytometry. Alkaline phosphatase (ALP) staining and alizarin red staining were used to identify the ability of cells to differentiate. RNA was collected on Days 0, 7 and 14 of the osteogenic induction of hDPSCs, and qRT-PCR was used to detect the relative expression of TUG1. The hDPSCs were stably transfected with a lentiviral vector containing the TUG1-silenced pSLenti-U6-shRNA(TUG1)-CMV-EGFP-F2A-Puro-WPRE to silence TUG1. The ability of hDPSCs to proliferate was assessed with the CCK-8 method. ALP and alizarin red staining and quantitative detection were used to detect the ALP activity and formation of mineralized nodules of hDPSCs. The expression levels of dentin sialophosphoprotein (DSPP), dentin matrix protein-1 (DMP-1), Runt-associated transcription factor 2 (Runx2), osteocalcin (OCN) and osteopontin (OPN) genes and proteins were measured by qRT-PCR and Western blot. Results The hDPSCs were successfully isolated and cultured, and TUG1 expression was significantly increased during osteogenic differentiation (P<0.05). The hDPSCs proliferation was suppressed after silencing TUG1(P<0.05). After osteogenic induction, ALP and alizarin red staining showed that ALP activity and mineralized nodules were suppressed by silencing TUG1. The expression levels of the odontogenic differentiation gene DSPP and DMP-1 and the osteogenic differentiation gene Runx2, OCN and OPN were also significantly decreased (P<0.05). Conclusion Knocking down TUG1 can inhibit the proliferation and osteogenic/odontogenic differentiation of hDPSCs.

Objective To discuss and summarize the preventive measures and treatment methods for aspiration/ingestion during dental procedures. Methods One case of aspiration during an implant operation was reported, and the literature on aspiration/ingestion during oral procedures was reviewed. Results An implant screwdriver accidentally slipped into the mouth of the patient during implant surgery. The patient experienced no obvious discomfort except a few coughs. The surgeon and assistant paused the procedure immediately to search for the screwdriver, but it was not found. The patient declared that there was no special abnormality, such as breathing disorder or chest distress, so we considered that the foreign body was ingestion. After the implant surgery was completed, no foreign body was found in the stomach via gastroscopy. Chest X-ray and CT showed a dense metal shadow in the lower lobe of the left lung. Under local anesthesia, bronchoscopy and biopsy forceps were used by respiratory physicians to clip out the foreign body. After removal of the foreign body, the patient had no obvious discomfort but a slight cough. Cephalexin and metronidazole were given for three days to prevent infection. Three days later, the patient had no complaints of respiratory discomfort. After reviewing the literature, we found that the operation should be paused immediately after aspiration/ingestion occurs during dental procedures and that the dental chair should be laid down to prevent the foreign body from descending deeper, which may increase the difficulty of removal and cause gastrointestinal and respiratory tract injury. The position of the foreign body should be determined by imaging examination, and the corresponding means to remove the foreign body should be performed. Conclusion Patients may have no obvious symptoms after aspiration/ingestion during dental procedures, and the foreign body can be removed after imaging examination.

The transpalatal arch (TPA) is widely used in clinical orthodontics for various purposes. This article reviews the versatile clinical uses and mechanics of TPAs for clinical reference. Traditionally, TPA is conceived as an anchorage reinforcement device. However, the literature does not support the sole use of TPA for anchorage control. TPA, combined with other conventional anchorage means, can only provide sufficient anchorage in certain cases. As an adjunct to fixed appliance treatment, TPA can be applied for arch width maintenance, tooth alignment and habit braking to improve treatment efficiency and reduce side effects. Meanwhile, TPA can be used to provide active orthodontic forces for maxillary molars to move or rotate bilaterally and unilaterally in all three planes of space, especially on occasions where molar rotation and transverse discrepancy exist. A two-couple system is formed with a TPA connecting bilateral maxillary first molars, the mechanical analysis of which can improve the understanding of treatment mechanics and make tooth movement more predictable. In recent years, TPA has also been used in combination with temporary anchorage devices for maxillary molar intrusion and full arch mesialization or distalization. The combined use of TPA with TADs and maxillary skeletal expanders could be further investigated in the future.

Objective To investigate the antibacterial effect of a new photosensitizer, indocyanine green (ICG)-mediated photodynamic therapy, on a biofilm of Fusobacterium nucleatum (F. nucleatum) in vitro. Methods The biocompatibility of the photosensitizer ICG was detected by CCK8. F. nucleatum (10⁸ CFU/mL) was cultured in anaerobic conditions (80% N₂, 10% H₂ and 10% CO₂) mixed with the photosensitizer ICG at concentrations of 0, 10, 20, 30, and 40 μg/mL and then treated with antibacterial photodynamic therapy (808 nm near infrared light with an intensity of 0.1 W/cm² for 3 min), and a mature biofilm was formed after 2 days. The bacteriostatic effects of different concentrations of ICG on F. nucleatum biofilms were compared by colony formation unit count (CFU). The effect of ICG on the formation of F. nucleatum biofilms and biofilm metabolic activity was determined by crystal violet quantification and MTT assays. The effect of ICG on the formation of extracellular polysaccharides in F. nucleatum biofilms was determined by the phenol-sulfuric acid method. The change in the number of bacteria was observed by confocal microscopy. Results CFU and biomass of the biofilm gradually decreased with increasing ICG concentration, and there were significant differences compared with the control group. Meanwhile, the metabolic activity of the biofilm and the production of extracellular polysaccharides also showed a significant difference between the ICG groups and the control group (P<0.01). At the same time, laser confocal microscopy showed that the number of living bacteria decreased gradually. Conclusion Antibacterial photodynamic therapy with photosensitizer ICG can effectively inhibit the formation of F. nucleatum biofilms.

Chronic periodontitis is a prevalent disease; if left untreated, it is a main indication for tooth extraction and can lead to tooth loss. The reactive soft tissue, formed as a result of the immune response to chronic inflammation, is left in the compromised socket. The major concern is how to deal with the residual reactive soft tissue. Conservative thought states that the reactive soft tissue should be completely debrided. In addition, novel practices concerning the reactive soft tissue were proposed in recent trials, which demonstrated that there might be merits for soft and hard tissue regeneration with preservation of the reactive soft tissue. Studies have shown that mesenchymal stem cells exist in inflammatory reactive soft tissue, stressing their potential in tissue regeneration. Although the therapeutic value is highly promising, the specific components of the reactive soft tissue and the standard on whether it should be preserved need further investigation.

Ideal sutures can provide great fixation, wound closure and a stable environment for healing of the surgical site. Tension-free apposition sutures are important for tissue regeneration and could tackle insufficient amounts of soft and hard tissue, especially in missing tooth sites that require implantation. The internal horizontal mattress suture, similar to the conventional horizontal mattress suture, forms a rectangle that can be bisected by the incision with both intrusion and extrusion of the needle on each side. On the basis of the rectangle, the internal horizontal mattress suture emphasizes that the suture should be located below the incision, so the eversion of the wound margin is the highlight of this procedure. The internal horizontal mattress suture could stabilize the graft on the targeting tissue, realize the fixation of the collagen membrane, apically repositioned flap and soft tissue graft, reduce the tension on the incision, and further release the tension of the incision margin. Beyond the primary need for fixation and wound closure, internal horizontal mattress sutures can also achieve stress interruption that reduces the interference of the surrounding muscle and can better master wound tension with the assistance of interrupted sutures. Given the above advantages, horizontal internal mattress sutures have great potential in the application of implant-related regenerative surgery. In this review, according to our experience in clinical practice and the literature, we summarize the advantages of internal horizontal mattress sutures in tissue augmentation. In addition, the sites and sequence to insert the needle and the spatial relationship between the suture and incision are clarified with the rationale of the naming pattern, which is conducive to experience exchange and clinical practice.

Vertical bone augmentation surgery still faces considerable challenges in clinical practice due to various problems, such as difficulty in restoring the ideal alveolar bone height and biological complications, and because it is highly technically sensitive. Plasmatrix is derived from patients’ own blood, and it can effectively promote the vascularization of the regenerated area, recruit stem cells, and reduce inflammation when used in vertical bone augmentation. Based on studies published worldwide, this article first divides vertical bone augmentation into 3 categories according to the height of the expected alveolar ridge, namely, type Ⅰ, the required vertical bone gain is less than 4 mm; type Ⅱ, the required vertical bone gain is between 4-8 mm; and type Ⅲ, the required vertical bone gain is greater than 8 mm. In the type Ⅰ vertical bone augmentation, the plasmatrix bone block is directly placed in the defect area and covered with the plasmatrix membrane before tension-free suturing; in the type Ⅱ vertical bone augmentation, the plasmatrix bone block should be placed in the defect area and fixed with titanium nails and then covered with an absorbable collagen membrane and plasmatrix membrane with a tension-free suture; in the type Ⅲ vertical bone augmentation, additional active ingredients (such as bone morphogenetic protein, autologous bone, etc.) should be added to the plasmatrix bone block and strong fixation (such as titanium nails) should be used. Absorbable collagen and plasmatrix membranes should be used to cover the surface of the bone block, and the flap should be sutured. According to different types of vertical bone augmentation categories, the above methods optimize the vertical bone augmentation effect. This article aims to provide a reference and guidelines for oral clinicians to fully understand plasmatrix and simplify the classification and operation of vertical bone augmentation.

Objective To analyze changes in proteoglycan and its correlation with alveolar bone resorption in periodontitis. Methods Twelve eight-week-old C57BL/6J male mice were selected, and the periodontitis model was established by ligating the right maxillary second molar with 6-0 silk thread. The nonligated part of the left maxilla was used as the control. The mice were killed 14 days after the operation. Micro-CT was used to assess alveolar bone resorption. HE staining was used to observe the alveolar bone profile, and TRAP staining was conducted to examine the positive rate of osteoclasts. The expression of proteoglycan-related genes, such as aggrecan (ACAN), biglycan (BGN), versican (VCAN), decorin (DCN), osteoclast-related genes, such as cathepsin K (CTSK), matrix metalloprotein-9 (MMP-9), and receptor activator of nuclear factor kappa-B ligand (RANKL), and inflammation-related genes, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), was detected by real-time quantitative PCR. Additionally, the correlation of the expression of proteoglycans with osteoclast-related genes and inflammation-related genes was evaluated by Pearson correlation analysis. Results The resorption of alveolar bone on the periodontitis side increased. TRAP staining showed that the number of osteoclasts was substantially increased in the maxilla with periodontitis. Real-time quantitative PCR demonstrated that compared with the control side, the expression of proteoglycan-related genes, such as ACAN, BGN, and DCN, was decreased, whereas the expression of the VCAN gene was significantly increased in the periodontitis side. Meanwhile, the expression of osteoclast-related genes, such as CTSK, MMP-9, and RANKL, and inflammation-related genes, such as IL-1β, IL-6, and TNF-α, was markedly increased in the periodontitis side (P<0.05). Pearson correlation analysis indicated a negative correlation between the expression of proteoglycans and the mRNA levels of osteoclast-related genes and inflammation-related genes (P<0.05). Conclusion The expression of proteoglycan was closely related to alveolar bone resorption in a periodontitis model.

Endodontic microsurgery is a vital treatment modality for teeth with persistent periradicular pathoses that have not responded to nonsurgical retreatment. The principle is to determine the reason for failure, completely eliminate the infection and promote periapical healing. Within recent years, endodontic microsurgery has evolved to become standardized and presents with a high success rate. However, its outcome is still influenced by many factors, including anatomy, periodontal condition, crown-to-root ratio, occlusion, the type of periradicular lesion, and prosthesis. Moreover, endodontists always concentrate on “the apex”, paying little attention to the general preoperative evaluation, accurate diagnosis, and comprehensive treatment plan. This article reviews the latest literature on these issues and the clinical experience of our research group and discusses the correlation between endodontic microsurgery and other oral disciplines, including periodontology, prosthodontics, oral implantology, oral and maxillofacial surgery and orthodontics. The oral interdisciplinary assessment should be made with comprehensive consideration of the root canal system, periradicular lesion, adjacent anatomical relationships, periodontal condition, occlusion, and esthetic rehabilitation. Based on these findings, the continuity of treatment will be optimized, and the best treatment plan will be proposed to provide clinical strategies for the diagnosis and treatment of complex periradicular diseases.

With the development of computer-aided surgery and rapid prototyping via 3D printing technology, digital surgery has rapidly advanced in clinical practice, especially in the field of oral and maxillofacial surgery. 3D printing technology has been applied to the functional restoration and reconstruction of the jawbone. Before surgery, a 3D digital model is constructed through software to plan the scope of the osteotomy, shape the bone graft and plan the placement of the implant. Additionally, 3D models of personalized surgical instrument guides are printed prior to surgery. With these 3D-printed models and guides, accurate excision of the jaw tumor, accurate placement of the grafted bone and precise placement of implants can be achieved during surgery. Postoperative evaluation of accuracy and function shows that 3D printing technology can aid in achieving the biomechanical goals of simultaneous implant placement in jaw reconstruction, and in combination with dental implant restoration, the technology can improve patients' postoperative occlusal and masticatory functions. Nevertheless, 3D printing technology still has limitations, such as time-consuming preparation before surgery. In the future, further development of 3D printing technology, optimization of surgical plans, and alternative biological materials are needed. Based on domestic and foreign literature and our research results, we have reviewed the process and clinical application prospects of jaw reconstruction via 3D printing technology to provide a reference for oral and maxillofacial surgeons.

At present, implant surgery robots have basically achieved "surgical intelligence", but "brain-inspired intelligence" of robots is still in the stage of theory and exploration. The formulation of a clinical implantation plan depends on the timing of implantation, implantation area, bone condition, surgical procedure, patient factors, etc., which need to evaluate the corresponding clinical decision indicators and clinical pathways. Inspired by evidence-based medicine and the potential of big data and deep learning, combined with the data characteristics of clinical decision indicators and clinical pathways that can be quantitatively or qualitatively analyzed, this review simulates the cognitive behavior and neural mechanisms of the human brain and proposes a feasible brain-inspired intelligence scheme by predicting the decision indices and executing clinical pathways intelligently, that is, "select clinical indicators and clarify clinical pathways -- construct database -- use deep learning to intelligently predict decision indicators -- intelligent execution of clinical pathways -- brain-inspired intelligence of implant decision-making". Combined with the previous research results of our team, this review also describes the process of realization of brain-inspired intelligence for immediate implant timing decisions, providing an example of the comprehensive realization of brain-inspired intelligence of implant surgery robots in the future. In the future, how to excavate and summarize other clinical decision factors and select the best way to realize the automatic prediction of evidence-based clinical indicators and pathways and finally realize the complete intellectualization of clinical diagnosis and treatment processes will be one of the directions that dental clinicians need to strive for.

Objective To evaluate the osteogenic effects of using a 3D-printed bredigite(BRT) bone scaffold on the Onlay graft in rats. Methods BRT scaffold material was fabricated by 3D printing technology as the experimental group, β-tricalcium phosphate(β-TCP) bone scaffolds were used as the control group. The scaffolds were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical test and in vitro degradation test. An animal model of Onlay graft in SD rats was established. According to the different grafts, the animal model was divided into autogenous bone transplantation group (Auto Group), β- TCP group and BRT group. At 12 weeks after the operation, the target line was obtained for gross observation, micro CT scanning and analysis, and HE staining histological analysis. Results BRT scaffolds have distinctive surface topographywith relatively uniformly sized pores in SEM imaging. A higher mechanical strength and degradation rate was obtained with BRT scaffolds（46.80 ± 3.44) MPa, compared to β-TCP scaffolds（11.29 ± 1.30) MPa (P<0.001）. At day 35 in vitro, the mass of BRT was degraded 27.18% ± 1.41%, and the Ca, Mg and Si ion concentrations were maintained at a high level in BRT group. Micro CT and histological quantitative results showed that the proportion of bone regeneration in BRT group was 16.83% ± 2.11% and 19.08% ± 2.17%, respectively, which was higher than that in the β- TCP group (8.48% ± 1.85%, 10.81% ± 1.33%) (P < 0.05). Conclusion 3D-printed BRT scaffolds promote bone regeneration in the Onlay graft.

Objective To study the morphological characteristics of the posterior canal of mandibular molars in the Shanxi population, provide theoretical guidance for the surgical safety of the retromolar region and mandibular ramus. Methods A total of 400 patients in the Department of Stomatology of the First Hospital of Shanxi Medical University were randomly selected to screen the images that met the inclusion criteria. Cone beam computed tomography and digital software were used to measure the relevant data. Divide the classification of the retromolar canal, and establish a three-dimensional model of the retromolar canal. The number, distribution and course of the retromolar canals were observed and counted, and the relevant data were measured. Results A total of 368 samples were included in the study, and the retromolar canal was present in 84 samples, with an incidence of 22.83%. There were 47 men and 37 women; there were 55 on the left side and 52 on the right side, with no significant difference between the gender. In this study, the mandibular angle was bounded by the posterior margin of the retromolar region, and the initial position of the retromolar canal was divided into two regions: A (mandibular ramus area) and B (retromolar area). The retromolar canal can be divided into types A1 to A5 and B1 to B4 according to its shape and course, with type A3, which starts from the mandibular ramus area and bends upward along the medial side of the mandible, being the most common, followed by type B3, and type A4 being the least common. The mean length of the retromolar canal was (10.95 ± 2.76) mm, the mean diameter of the starting position was (1.22 ± 0.50) mm, the mean diameter of the retromolar foramen was (1.05 ± 0.39) mm, and the mean distance from the retromolar foramen to the distal enamel cementum boundary of the third molar was (9.50 ± 3.66) mm. Conclusion The incidence of retromolar canals is high in the population of Shanxi Province. It is necessary to note the presence of these canals in order to avoid intraoperative and postoperative complications when performing surgery on the retromolar region and mandibular ramus.

Objective To investigate the inhibitory effect of polydopamine (PDA) on enamel demineralization in isolated teeth and the induction of hydroxyapatite (HA) production on the surface of demineralized enamel to provide a novel protocol for the prevention and treatment of enamel demineralization. Methods Twenty isolated bovine teeth were cut into 20 enamel slices and randomly divided into an experimental group and a control group, with 10 slices in each group. The enamel slices in the experimental group were immersed in 2 mg/mL freshly prepared dopamine solution and incubated for 24 hours at room temperature in the dark to prepare the PDA coating, while the control group was left untreated. Then, the isolated bovine teeth, with and without PDA coating, were immersed in artificial demineralization solution at 37 °C for 3 days, followed by 7 days in simulated body fluid (SBF), and the immersion solution was changed daily. The surface morphology of enamel was observed by scanning electron microscopy (SEM), the calcium/phosphorus ratio of the enamel surface was analyzed by energy dispersive spectroscopy (EDS), and the characteristic functional groups in enamel deposits were analyzed by Fourier transform infrared spectroscopy (FTIR). Results Compared with the control group, the number of demineralized pores produced after 3 d of enamel demineralization with polydopamine coating was less, and the diameter was smaller. EDS elemental analysis showed that the Ca/P ratio after enamel demineralization was 2.37 in the experimental group, which was smaller than the 2.53 ratio in the control group. In the remineralization experiment, after 7 days of remineralization of PDA coated enamel in the experimental group, lamellar grains were produced on the enamel surface, and the growth showed obvious directionality, growth regularity and uniform arrangement. In the control group, the surface of enamel was flocculent mineral deposit, and the crystallinity was poor. The FTIR results proved that the enamel surface deposit of PDA-coated enamel was HA after 7 d of remineralization. Conclusion PDA can affect the nucleation process of HA and promote the production of HA on the surface of demineralized enamel.

Objective To investigate the clinicopathological characteristics, imaging manifestations, genetic manifestations, diagnosis and treatment of juvenile hyaline fibromatosis. Methods A case of juvenile hyaline fibromatosis was reported, and the patient's clinical manifestations, imaging examinations, histopathological examinations, genetic changes and treatment were summarized and analyzed. Results Juvenile hyaloid fibromatosis is more common in infants and children. This patient had typical clinical and pathological manifestations, including posterior occipital masses, skin and subcutaneous nodules, gum hyperplasia, joint contractures, and joint osteolytic lesions. The histopathological lesions were characterized by the proliferation of spindle cells in the tissue accompanied by a large amount of amorphous transparent matrix. Genetic testing was performed to confirm an ANTXR2 gene mutation, consistent with the known genetic changes of juvenile hyaline fibromatosis. The 6-month follow-up of the patient showed that there was no obvious recurrence after resection of the gum and facial mass. In addition to surgery, the treatment of this disease requires multidisciplinary symptomatic treatment combined with rehabilitation and supportive treatment to achieve a better prognostic effect. Conclusion Juvenile hyaline fibromatosis is a rare nonneoplastic autosomal recessive genetic disease. Mutations in the ANTXR2 gene lead to disorders of collagen synthesis and metabolism in the tissues and further cause subcutaneous nodules, gingival hyperplasia, joint contractures and bone dissolution.

Objective To study the postoperative soft and hard tissue changes and aesthetic effect of immediate implantation and provisionalization (IIPP) combined with guided bone regeneration (GBR) for a single anterior maxillary tooth with a thin facial bone phenotype. Methods A total of 34 patients with thin facial bone (<1 mm) were categorized into two groups: a flapped GBR group and a flapless group. Tooth extraction and IIPP were conducted at the sites in both groups. Implant survival rates, dimensional changes in soft and hard tissues during the six- and twelve-month follow-ups, the pink esthetic score (PES) and patient satisfaction scores at the twelve-month follow-up were measured. Results The implant survival rates were 100% in both groups, and no complications occurred during the 12 months after surgery. The facial bone thickness remained over 2 mm on all measured sides, and the height of the facial bone crest remained at 1.39 mm at the 12-month follow-up in the flapped GBR group, while the facial bone thickness remained less than 2 mm on all measured sides, and the height of the facial bone crest remained at 1.03 mm at the 12-month follow-up in the flapless group. The absorption of facial bone at all measured sides in the flapped GBR group was greater than that in the flapless group (P<0.05). There was no significant difference between the two groups in the dimensional changes of labial soft tissues during the six- and twelve-month follow-ups (P>0.05). The mean PES scores were 10.29 ± 2.34 for the flap GBR group and 10.12±1.78 for the flapless group (P = 0.807). The mean patient satisfaction scores were 8.65 ± 1.27 in the flapped GBR group and 8.76 ± 1.25 in the flapless group, and the patients in both of the groups were satisfied with the esthetic outcomes (P = 0.787). Conclusion IIPP combined with GBR might be a prospective treatment strategy for a single anterior maxillary tooth with a thin facial bone phenotype, but the esthetic risks should never be ignored.

Objective To investigate the inhibitory effect of honeysuckle on Streptococcus mutans UA159 in vitro. Methods We used a double-dilution method to measure the minimum inhibitory concentration (MIC) of honeysuckle against Streptococcus mutans UA159. Lonicerae lonicerae powder was dissolved in the solvent DMSO, different concentrations of liquid medicine were prepared, and bacterial liquid was added. The solution control group and bacterial liquid control group were set at the same time. The growth and acid production of UA159 were determined using antibacterial experiments. A growth curve and acid production curves were drawn, and the adhesion rate and adhesion inhibition rate were calculated. The effect of honeysuckle on the formation of Streptococcus mutans UA159 was determined by crystal violet quantification, and a microscope and a scanning electron microscope were used to observe biofilm formation and structural changes. Results The MIC of honeysuckle against Streptococcus mutans UA159 was 12.5 mg/mL. The bacteriostatic experiments showed a difference in the growth, acid production and adhesion of UA159 after honeysuckle treatment (P<0.05) compared with the controls, and the inhibitory effect increased as the drug liquid concentration increased. Crystal violet quantification showed a significant difference in biofilm formation between the pharmaceutical liquid group and the control group (P<0.05). Meanwhile, the forward microscope showed a significant decrease in biofilm formation. Under SEM, the number of bacteria decreased significantly at 0, 6 and 12 h after honeysuckle addition. Conclusion Honeysuckle inhibits the growth and acid production of UA159 and inhibits adhesion and the formation of biofilms.

The properties of adhesives and light-cured resin composites are closely related to the repair of dental defects. Therefore, improving the properties of adhesives and resins composite to increase the success rate of filling has been the focus of research in the field of prosthodontics in recent years. Current studies have confirmed that temperature can change the properties of adhesives and light-cured resin composites, affecting their repair effect. A proper storage temperature ensures the good performance of materials: the self-etching adhesive system should be refrigerated, and the light-cured resin composite should be refrigerated or stored at room temperature according to its composition, proportion and other properties; however, the appropriate storage temperature for the etch-and-rinse adhesive system is not clear. The appropriate application temperature could improve the fluidity, monomer conversion, bonding strength, compressive strength and other properties of the materials to improve the quality of filling restoration. However, there is a wide variety of adhesives and resin composites, and the effect of temperature on each material is different. Thus, it is still necessary to explore the temperature range for material storage, precooling and preheating. Few studies have been performed in vivo, and the clinical restorative effects of adhesives and resin composites stored and used at different temperatures need to be further studied.

Glass ionomer cement (GIC) is widely used as a common filling material in dentistry but still exhibits problems with secondary caries and fractures. Thus, the antibacterial and anti-caries performance of GIC needs to be further improved. In recent years, natural antimicrobial components have become more desirable due to their good biological properties and low drug resistance. In this review, the natural antimicrobial ingredients in GIC modification are classified, reviewed and summarized according to the different sources of antimicrobial ingredients. In terms of animal origin, chitosan and casein phosphopeptide-amorphous calcium phosphate exhibit antimicrobial properties without affecting the mechanical properties of materials; propolis and bioactive enzymes have good biocompatibility; in terms of plant origin, polyphenols help improve the antimicrobial and mechanical properties of the material; arginine has a good remineralization effect; and plant essential oils have a certain ion release effect. In terms of microbial origin, antibiotics greatly improve the antibacterial properties of materials; in addition, the combined application of natural antimicrobial ingredients also exhibited excellent performance. Despite these advantages, the optimal addition concentration and biocompatibility in vivo are questions that need to be further explored before clinical applications can be achieved.

Tissue engineering provides a new possibility for pulp regeneration. As one of the three elements of tissue engineering, scaffolds have attracted increasing attention. Because the root canal system is limited by the unique anatomical structure of the long and narrow lumen, the preformed scaffold cannot be completely covered with the whole root canal space, although it is convenient to apply, so the injectable scaffold may be an ideal choice for pulp tissue engineering. Hydrogels are hydrophilic polymer networks with physical properties similar to soft tissues. They can provide a porous hydrophilic microenvironment, which facilitates the diffusion of oxygen and nutrients. In recent years, researchers have used injectable hydrogels with different mechanical properties and/or loaded biologically active ingredients as scaffolds to promote revascularization and the regeneration of pulp. The results show that natural polymer hydrogels, synthetic polymer hydrogels, and composite hydrogels combining natural and synthetic polymers all have excellent biocompatibility. The types and mechanical properties of hydrogels and the addition of bioactive ingredients can influence the behavior of stem cells, and gelatin-based hydrogels and fibrin-based hydrogels can also achieve rapid vascularization, which creates the conditions for the formation of pulp-like tissues. Among them, photocrosslinked methacrylated gelatin/hyaluronic acid hydrogels, two/multicomponent hydrogels combined with chitosan with antibacterial and temperature-sensitive properties and new self-assembled peptides have become major research topics in recent years due to their excellent properties. To develop suitable hydrogel scaffolds and promote their application in pulp regeneration, this article reviews the research progress in the types, preparation, and application of injectable hydrogels used for dental pulp regeneration.

Oral mucosal disease is a general term for a type of disease that mainly affects the oral mucosa and surrounding soft tissues. In the treatment of oral mucosal diseases, due to the particularity of the anatomical location, the use of topical administration is relatively simple and convenient; drugs can easily accumulate in the lesions, and at the same time, they can also avoid adverse reactions caused by systemic drug delivery. Topical administration has become an important and even preferred option for the treatment of oral mucosal diseases. There are various types of topically used drugs for oral mucosal diseases, such as glucocorticoids (triamcinolone acetonide), immunomodulatory drugs (tacrolimus), antiseptic drugs (chlorhexidine), pain relievers (lidocaine) and proprietary Chinese medicines (aloe vera gel). Among these drugs, although the most widely used liquid formulations such as gargles and sprays are easy to use, they are not conducive to local retention of drugs due to the particularity of the oral environment and function. Based on this, researchers have continuously improved the dosage form of the drug, and developed a series of semi-solid pharmaceutical preparations such as gels and ointments, some of which have exerted good curative effects in clinical work. In addition, although films, patches and other solid oral mucosal topical pharmaceutical preparations have few clinical applications, they have also been widely researched and described and are expected to become the mainstream dosage form in the future. In general, with the improvement of dosage forms, topical administration is playing an increasingly important role in the treatment of oral mucosal diseases. Therefore, combined with basic research and clinical reports, this article reviews the application of topical drug delivery in the treatment of oral mucosal diseases.

Objective To explore the effect on children's occlusion and temporomandibular joint (TMJ) after placement of preformed metal crowns and provide a reference for the restoration of defective primary molars. Methods A total of 39 children who underwent all primary molar metal crown restorations under general anesthesia were enrolled. The participants underwent occlusal contact area, percentage of total occlusal force, asymmetric ratio of occlusal force and occlusal contact time examinations with the T-scan computerized occlusal analysis system. Vertical dimension of occlusion (VDO) was measured using a dental vertical dimension gauge. TMJ dysfunction signs were recorded using the modified clinical dysfunction index (Di), and TMJ dysfunction symptoms were recorded using questionnaires. All data were collected at pretreatment, 1-week, 1-month, 3-month, and 6-month follow-up visits. Results The occlusal contact area at the 3-month and 6-month follow-up visits returned to the occlusal contact area of pretreatment, and the difference was statistically significant (P>0.05). Compared with pretreatment, the percentage of total occlusal force at the 3-month and 6-month follow-up visits increased significantly, and the difference was statistically significant (P<0.05). The asymmetric ratio of occlusal force and the occlusal contact time were significantly decreased at the 6-month follow-up visit (P<0.05). The vertical dimension of occlusion recovered after one month of treatment (P>0.05). The final statistical analysis of the TMJ assessment showed that there was no significant difference in the clinical disorder index and TMJ dysfunction symptoms before and after treatment (P>0.05). Conclusions After undergoing all primary molar metal crown restorations, occlusal re-equilibrations were attained after approximately one month. The percentage of total occlusal force and occlusal stability were significantly increased after six months of treatment, without significant temporomandibular joint dysfunction.

Objective To investigate the effect of immediate and delayed implant placement on dimensional changes in hard and soft tissues as well as esthetic outcomes. Methods A total of 40 maxillary single anterior teeth with a dehiscence defect on the labial bone (≤4 mm) were categorized into two groups according to the timing of implant placement: immediate implant placement (n = 20) or delayed implant placement (n = 20). Guided bone regeneration (GBR) was conducted at the sites using a flap approach, and the implants were given immediate provisionalization. Implant survival rates, dimensional changes in hard and soft tissues during the six- and twelve-month follow-ups, and pink esthetic scores (PESs) were measured. Results The implant survival rates in both groups were 100%, and no complications occurred during the follow-up time. There was no significant difference between the two groups at the measurement sites in the dimensional change of hard and soft tissues during the six- and twelve-month follow-ups. The largest resorption was observed at the implant neck, with a loss of (1.29 ± 0.71) mm in the immediate implant placement group and (1.43 ± 0.19) mm in the delayed implant placement group. The mean PES scores were (10.95 ± 1.51) for the immediate implant placement group and (11.05 ± 1.23) for the delayed implant placement group. Conclusion Immediate implantation or delayed implantation combined with GBR and immediate provisionalization might both be a prospective treatment strategy for a maxillary single anterior tooth with a dehiscence defect on the labial bone.

Objective To investigate the adverse reactions of resin cement used for dentin bonding and its influencing factors. Methods Patients with dental defects treated with resin cement dentin adhesive for direct composite resin repair or full crown indirect repair were selected as the research objects. The occurrence and causes of adverse reactions, such as dental pulp lesions, soft tissue adverse reactions, and restoration loosening and falling off 7 days, 1 month, 3 months, 6 months, and 1 year after treatment, were analyzed retrospectively. Results Among the 14 776 teeth of 5 971 patients who used resin cement dentin adhesive, 580 cases (3.93%) had adverse reactions. Univariate analysis showed that the incidence of adverse events was highest in teeth with the "full crowns (fixed partial dentures)" restoration type at 7 days, 1 month, and 12 months after treatment. At 7 days after treatment, the incidence of adverse events was the highest in teeth with a preparation depth of "near pulp after preparation". At 7 days and 3 months after treatment, the incidence of adverse events was the highest in teeth with " dentin conditioner-adhesive-resin" treatment of the bonding surface. Multivariate analysis indicated that pulp perforation and pulp capping after tooth preparation were risk factors for adverse events 7 days after treatment (OR=2.610), and the “dentin primer-adhesive-resin” bonding surface treatment method was a protective factor for adverse events 7 days and 3 months after treatment (OR<1). Conclusion When resin cement dentin adhesives are used for direct or indirect restoration, the tooth preparation level and bonding surface treatment method may affect the occurrence of adverse events. pulp perforation, and pulp capping after tooth preparation, and self-etching bonding may contribute to adverse reactions.

Objective To detect WNT10A gene mutations in patients with oligodontia or anodontia (≥6 teeth missing) and analyze their dental phenotype. Methods Patients with oligodontia or anodontia were enrolled from the clinic for oral examination, genetic history collection and whole exon sequencing, and patients with WNT10A gene mutations were included. Sanger sequencing was utilized to validate the WNT10A gene variations in probands and family members compared with the normal sequence. The pathogenicity of WNT10A mutations was evaluated by functional prediction, conservation analysis and structure prediction of protein mutants. Implant rehabilitation was applied to restore the patients' oral function. Results Five WNT10A gene mutations were detected in six unrelated patients, and c.26G>A (p. Trp9X) and c.1036delT (p. Cys346fs) were novel mutations with pathogenic potential. The mean number of missing teeth was (15.33±8.64) per case. The most frequently missing permanent teeth were maxillary canines (100%), and the least frequently missing teeth were mandibular first molars (25%). Implant rehabilitation was applied in five patients, and patients were found to have ideal implant osseointegration and functional restoration. Conclusion This study identified novel WNT10A gene pathogenic variants, enriching the WNT10A gene spectrum and providing new evidence for genetic diagnosis and prenatal consultation. Implant rehabilitation was also proven to be a treatment option for these patients.

Objective To explore the changes in root volume and root resorption in incisor arteries from adult patients with skeletal class Ⅲ malocclusion before and after camouflaged orthodontic treatment and to provide a reference for the clinic. Methods Thirty permanent dentition adult patients with skeletal class Ⅲ malocclusion were included from the Orthodontic Department. CBCT data of each patient at pretreatment and posttreatment were acquired, and 3D digital root models were reconstructed. The whole and segmented root volumes (cervical part, bodily part and apical part) of the right incisors were calculated. Results The root volumes (whole, cervical part, bodily part and apical part) posttreatment were smaller than those pretreatment (P<0.001). Maxillary central incisors and lateral incisors showed similar resorption in the cervical root and bodily root and more changes in the apical root, but there was no significant difference (P>0.05). Mandibular central incisors and lateral incisors showed more root resorption in the apical root than in the cervical root and bodily root (P<0.01). The absorption ratio of all segmented roots in each incisor showed a significant difference (P<0.001), and apical absorption was the most obvious. There were no significant differences in root volume change amounts or the absorption ratio of the whole, cervical part and bodily part in all incisors (P>0.05). The absorption ratio showed a significant difference in the mandibular lateral incisors (P = 0.028). Conclusion After camouflaged orthodontic treatment of adult skeletal class Ⅲ malocclusion, incisor root resorption occurred mainly in the apical part, but the cervical and bodily parts should also be considered. There was a high risk of root resorption in the mandibular incisors.

Gingival recessions (GRs) result in root hypersensitivity, root surface caries, and esthetic problems. Various root coverage surgeries are being developed for periodontal plastic therapy. The tunnel technique (TUN) is one of the most widely applied surgeries due to its features of being minimally invasive, practical, excellent outcomes and long-term stability; however, there are still some limitations of this technique. The history and evolution from the envelope flap to TUN, including its efficiency when compared with coronally advanced flaps with a connective tissue graft (CTG), are reviewed in this paper. The limitations of TUN are discussed in consideration of our clinical experience; for example, there is high technique sensitivity when TUN is applied in GR>5 mm because of the great difficulty in covering the grafts. The advantages of surgical access, including vertical incisions in the vestibule, “W” type and pinhole access, are discussed for different situations. Mattress sutures and sling sutures in a single tooth or multiple teeth are applied in TUN. The different types of grafts, such as CTG, platelet-rich plasma, articular dermal matrix and xenogeneic collagen matrix, are described. Mechanical, chemical and biological conditioning of the root surface are recommended during surgery. Protecting the surgical area and taking antibiotics postoperatively are also very important. Finally, the modifications when TUN is applied with other kinds of techniques are discussed, including lateral closed TUN, laterally positioned flaps, double papilla flaps and frenuloplasty. Minimally invasive, esthetic, long-term stability and simplified techniques are the development trends of TUN in the future.