The clear aligner technique is a new orthodontic method to treat malocclusions by pre-fabricated removable clear appliance using artificial intelligence and maga data based calculations. Using the computerized 3D diagnosis and the treatment planning system, a clinician can complete the whole progress of a malocclusion treatment. The clear aligner technique changed many aspects of the orthodontic techniques and become a new step stone to the next development of the modern orthodontics. Before to use the clear aligner technique to treatment varied malocclusions, there are two main questions should be answered: whether clear aligner could resolve malocclusions as effectively as the fixed appliance; Whether there was any differences between the clear aligner appliance and the fixed appliance when malocclusions were treated. The orthodontic intervention and comprehensive treatment for teenagers is the future of the clear aligner clinic application. This article is to classify the clinic indication of the clear aligner in teenagers；summarizing the characters of the clear aligner in orthodontic diagnosis, treatment planning and treatment result evaluation. With efforts of Chinese orthodontists, we believe that the clear aligner technique could be well used clinically and Chinese teenagers with malocclusions will be benefited from the development ultimately.

[Abstract] As a newly invented technique, aligner therapy has its advantages in the treatment of class II malocclusion. The aim of this article is to review the main treatment approach and their characteristics based on the author’s clinical experience and expertise.

Abstract: Clear aligner treatment is more and more popular with patients because of its esthetic, comfort, clean and convenience. More and more doctors pay attention to clear aligner because of the three-dimensional computer aided program design and its simplicity in clinical operation. In recent years, with the development of dental digital technology and materials, more widely clinical application, orthodontists' experience has been constantly accumulated, and the indications of clear aligner treatment have been expanding. In addition, clear aligner also have some weakness, such as insufficient control over long-distance tooth movement, differences between actual tooth movement and computer simulation. Based on case selection and treatment plan, this article elaborates the biomechanics, anchorage control, appliance design and risk of clear aligner in extraction cases treatment. It provides a reference for orthodontists to use clear aligner to treat extraction cases well.

Objective: To quantify the changes of alveolar bone defects in adults crowding upon non-extraction clear aligner treatment. Materials& Methods: Cone beam computed tomography (CBCT) scans from adults who complete the first sequence treatment upon non-extraction Invisalign aligner were examined retrospectively in order to record the volume and the incidence of alveolar defects three-dimensionally before and after treatment (T0 &T1). The data were collected and analyzed using the computer programs Mimics 19.0 and Magics 21.0. Differences in alveolar defects between T0 and T1 were analyzed with SAS 8.02 using the Wilcoxon test and Chi-square test for paired samples. The significance level was set at α =0.05. Results: Thirty patients (30 women, average age: 24.9±3.8 years) were chosen for retrospective evaluation. A total of 840 teeth were evaluated, of which were mainly on the buccal root surfaces(99.64%). 219 (26.07%) teeth were involved before treatment and the incidence increased to 35.24% after the treatment, among which the dehiscence in maxillary molars and mandible premolars were significantly increased after treatment(P <0.05). The average volume of alveolar defects in patients before treatment was 83.67±63.33mm3, and after treatment was 97.16±73.79mm3(P <0.05). The Wilcoxon tests showed highly significant increases in the mandible incisors, while showed highly significant decreases in the maxillary canines(P<0.05). Conclusion: Alveolar defect is a common finding in adults crowding before orthodontic treatment, and showed an increased tendency upon non-extraction clear aligner treatment. It is suggested that the three-dimensional integrity of alveolar bone should be fully evaluated in clinical treatment when using clear aligners, and the treatment plan should be reasonably designed to reduce the aggravation of alveolar bone defects.

Abstract Objective: To study the 3D direction movement and the expression efficiency of molar distalizaiton with bracketless invisible appliance. Methods: Adult patients of Angle Class I and Angle Class II were selected to use bracketless invisible appliance for molar distalization. Among them, group Angle Class I (9 cases), with the average age of 23 years old, make maxillary and mandibular molar distal movements. Group Angle Class II (10 cases), with the average age of 24 years old, make maxillary molar distal movement. The lateral cephalometric radiographs were taken before and after the treatment of molars, and calculate movement distance, angle, movement effciency, anchorage loss of anterior teeth in three dimensional direction. Statistical analysis of all data.Results: Angle Class II: the distal maxillary expression rate of the first molar and second molar were 65.86% and 71.68%. Angle Class I: the distal maxillary expression rate of the first molar and second molar were 73.88%and 77.73%. The distal mandibular expression rate of the first molar and second molar were 69.1% and 75.03%. There is a certain degree of molar distal titl and vertical upward intruding. There was no significant loss of anchorage in anterior teeth. Conclusion: The use of the bracketless invisible appliance is effective in molar distalizatioin, but with a certain degree of molar distal tilt, vertical upward intruding; the anchorage of anterior teeth is basically intact.

Abstract: Objective To evaluate the effects of self-adhesive resin cements and two different surface treatments on bonding strength and durability of lithium disilicate glass-ceramic. Methods 183 pieces of lithium disilicate plates were prepared and randomly divided into two main groups to receive sandblasting or HF etching. Each group was further divided into RU (RelyX Unicem), RU200 (RelyXTM U200) and RV (silane+RelyX Veneer) three subgroups to build bonded specimens. Then all the bonded specimens were divided into two groups to receive 24 h water storage or 20000 thermal cycles, followed by shear bond strength test and failure mode analysis. Microstructure was analyzed by a scanning electron microscope. Results SBS results revealed that etching with 9.5% HF resulted in a significant higher bond strength than sandblasting, and the three subgroups in each group achieved similar bond strength between resin and lithium disilicate glass-ceramic. After aging, the bond strength decreased and the proportion of adhesive failure in each group increased. Conclusions Acid etching yielded higher bond strength between resin and lithium disilicate than sandblasting; self-adhesive resin cement can achieve the desired bond strength and bond durability for bonding lithium disilicate without conditioning with silane.

Objective　To evaluate the blood compatibility of a new high entropy alloy AlFeCoCuTiNbx. Methods The hemocompatibility of the materials was tested by means of hemolysis test, dynamic coagulation test, anticoagulant time measurement and platelet adhesion test. Results AlFeCoCuTiNbx (X=0.4,0.5) alloy had the best blood compatibility, and the hemolysis rate of all samples was less than 0.5%. In the anticoagulant properties, the dynamic coagulation time and the prothrombin time Nb0.4 and Nb0.5 were nearly to the time of pure Ti, and Ti6Al4V, and were relatively prolonged compared with the other experimental groups, however there was no significant difference in PT test. Platelet adhesion experiments showed that Nb0.4, Nb0.5 had less platelet adhesion, agglomeration and pseudo-foot extension. Conclusion The high entropy alloy AlFeCoCuTiNbx (X=0.4, 0.5) has good blood compatibility ,which might have some certain application prospects in the medical field.

Objective　 This study intends to investigate the distribution of Porphyromonas gingivalis and Porphyromonas gingivalis’ two kgp gene type in primary periapical infection root canal, and to analyze the correlation between the genotypes and clinical symptoms. Methods　 We collect 190 cases of primary periapical infection patients in clinic. We collect sample from their infected root cannel and we extract bacteria DNA from the sample we collected. We use Polymerase Chain Reaction to determine the presence of Porphyromonas gingivalis. We get the kgp catalytic domain with the help of Polymerase Chain Reaction. Tru I enzyme digestion to the kgp catalytic domain help us to determine the Porphyromonas gingivalis gene polymorphism. After all, we use statistical methods to the analysis of the experimental data. Results　55 patients in 190 patients with primary periapical infection can be detected with Porphyromonas gingivalis. The detection rate of kgp Itype is 27.3%, while the detection rate of kgpⅡtype is 38.2%. Porphyromonas gingivalis were correlated with clinical symptoms. kgp I type were correlated with pain. Conclusions　 The kgp gene of Porphyromonas gingivalis which is in root cannel of primary periapical infection has gene polymorphism. Because some samples do not contain enough quantity of Porphyromonas gingivalis, it is sometimes difficult for method of kgp specific primers PCR to detect kgp gene. In further research, we will find more sensitive means to detect kgp gene in infected root canals.

Objective To evaluate the clinical efficacy of mineral trioxide aggregate (MTA) pulpotomy treatment for managing carious vital pulp exposure in permanent teeth. Methods The efficacies of pulpotomy with MTA and calcium hydroxide (CH) as pulp capping agents were compared. The weighted mean success rates (WSR) of reversible pulpitis group and irreversible pulpitis group of MTA pulpotomy were estimated, and subgroup analyses were conducted to assess the effects of different surgical procedures and apical development on the success rate of reversible pulpitis group and irreversible pulpitis group. Results MTA group was better than CH group in two-year curative effect. The one-year and two-year WSRs of reversible pulpitis group and the one-year WSR of irreversible pulpitis group were all 99%. In the subgroup of the reversible pulpitis group, one-year WSR and two-year WSR in mature permanent teeth group were respectively 100% and 97%, while in young permanent teeth group they were all 99%, in the coronal pulpotomy group they were 100% and 99%, in the partial pulpotomy group they were 99% and 97%. In the subgroup of the irreversible pulpitis group, one-year WSR in mature permanent teeth group was 99%, in young permanent teeth group it was 99% , in the coronal pulpotomy group it was 100%, and in the partial pulpotomy group it was 87%. Conclusion MTA is superior to calcium hydroxide from the perspective of the later results. The coronal pulpotomy and young permanent teeth may be beneficial to increase the success rate after operation.

Objective To compare the effects of different treatment methods before in-office bleaching to investigate the occurrence rate and level of teeth bleaching sensitivity with bioactive glasses (BGs) application. Methods 45 subjects were randomized into 3 groups. In group A, all subjects were applied with BGs desensitizer. In group B, all subjects were applied with transparent tray and BGs desensitizer. Group C was the control group, without any desensitizer application. In every subject, the conditions of 6 front teeth were observed. Desensitizer applications were used in group A and B, while no desensitizer treatment in group C. Sensitivity scores [recorded on a 10-point visual-analog scale (VAS)] were determined right after, 24 h, 48 h after the bleaching treatment in group A, B and C. The data of occurrence rate and level of teeth bleaching sensitivity with BSG application were analyzed and compared statistically. Results Bleaching sensitivity occurred in 33.33% of the subjects in Group A (Right after) and 13.33% of the subjects in Group B (VAS mean scores: 0.33±0.49, 0.13±0.35). Bleaching sensitivity occurred in 86.67% of the subjects in Group C (Right after) (VAS score: 1.53±0.82). There were significant statistical differences between VAS mean values of A, B and C right after group (P<0.05).24 hours after treatment, bleaching sensitivity occurred in 0% of the subjects in Group A and B, and 40% of the subjects in Group C (VAS score: 0.47±0.63). There were significant statistical differences between VAS mean values of A, B and C 24 h group (P<0.05). 48 hours after treatment, bleaching sensitivity occurred in 0% of the subjects in Group A and B, and 6.67% of the subjects in Group C (VAS score: 0.07±0.25). Bleaching sensitivity occurred in 86.67% of the subjects in Group C (Right after) (VAS score: 1.53±0.82). There were no significant statistical differences between VAS mean values of A, B and C 48 h group (P>0.05). Conclusion The application of BGs and transparent tray desensitizer may significantly reduce the occurrence rate of bleaching sensitivity and alleviate the symptoms.

Objective　 Using the laser cavity detection system DYAGNOdent(DD) to compare the effects of Duraphat and Fluor Protector on inhibition of enamel demineralization after fixed orthodontic appliance during three-months. Methods　In our department, 60 teenagers with straight-wire appliance were enrolled in the study, including 23 males and 37 females, aged 12-18 years with a mean of 14.8 years. This experiment adopted the self-control method. The right upper anterior teeth and premolars were given Duraphat as experimental group A, and the left lower anterior teeth and premolars were given Fluor Protector as experimental group B；The left upper anterior teeth and premolars did not receive any special treatment as control group A, and the right lower anterior teeth and premolars were given normal saline as control group B. Before bonding brackets, and 1 and 3months after bonding brackets, totally 3 times, the degree of enamel demineralization was detected by the laser cavity detection system, DIAGNodent. (DD).One-way ANOVA analysis was used to compare enamel demineralization whether there was statistical significance.Results　 (1)The DD detection values of the two experimental groups were both significantly lower than that of the control groups at 1 and 3months after bonding brackets, indicating that Duraphat and Fluor Protector could inhibit the enamel demineralization(P<0.05). (2)The DD detection values between experimental A and experimental B while 1 and 3months after bonding brackets showed no significantly difference (P>0.05), indicating that there were no significantly difference between the two kinds of fluoride varnish.Conclusions　(1) The patients with fixed orthodontic treatment are susceptible to enamel demineralization.(2) Duraphat and Fluor Protector with two different concentrations could both inhibit enamel demineralization during orthodontics. There is no significant difference between these two groups in inhibiting demineralization.

Objective　 To study the application of medical examination and treatment of occult submucous cleft palate (OSMCP). Methods Eight individuals of hypernasality without visible cleft palate who had been performed physical examination outside the hospital ruling out the systemic disease or any syndrome, were confirmed as subjects of velopharyngeal incompetence(VPI) after they were performed the speech assessment(scored by hypernasality severity）and the electronic nasopharyngoscopy inspection. Subjects who showed abnormal anatomy of levator veli palatine muscle (LVP) in the velum on the magnetic resonance imaging(MRI) were diagnosed as OSMCP. Operations were performed on OSMCP subjects to explore structures of LVP with reconstructions of LVP muscles and Furlow technique. Operated subjects received hypernasality assessment and inspection of velopharyngeal closure using electronic nasopharyngoscopy again three months after surgery. Results Six of eight VPI subjects showed disconnecting of LVP structures in the velum by the MRI examination. The surgery course verified that all six operated subjects lost continuity of the LVP in the soft palate and had levator muscles abnormal attachment forward. The six subjects’ hypernasality and their rates of VPI recovered obviously after the operations. Conclusion MRI can help diagnosis of OSMCP in an effective way. The operation of reconstruction of LVP muscles plus the Furlow technique has a potentiality to improve the velar function of OSMCP patients.

Objective　 To evaluate the treatment method and effect of maxillary sinusitis after maxillary sinus elevation by maxillary sinus anterior lateral wall puncture and irrigation. Methods 142 patients received maxillary sinus elevation in our hospital from 2012 to 2018, among whom 5 patients developed maxillary sinus inflammation about one week after surgery and were treated by maxillary sinus anterior lateral wall puncture and irrigation. Results All of the 5 patients treated by maxillary sinus anterior lateral wall puncture and irrigation got good effects. The symptoms of maxillary sinusitis disappeared after operation and the effusion of maxillary sinus cavity disappeared after CBCT examination. The osteogenesis effect in the maxillary sinus elevation was good and the implant was stable. The follow-up effect was stable after 1 to 6 years of routine restoration. Conclusion The treatment of maxillary sinusitis after sinus elevation by the anterior lateral wall puncture and irrigation of maxillary sinus has good effects.

Objective To evaluate the accuracy of cone-beam computed tomography (CBCT) and digital periapical radiographs (DPRs) for teeth length measurements by different doctors. Methods 46 CBCT images and 82 premolars were collected from the patients who were go?ing to undergo orthodontic treatment and would require premolar extractions. The teeth length measurements made by digital caliper was considered as the gold standard. The teeth length was measured by CBCT software on axial planes (APs), sagittal planes (SPs) and coronal planes (CPs) by two doctors respectively. Then the extracted teeth were matched the corresponding location of a dry skull. Standardized bisecting angle DPRs were taken of all the teeth and were then measured by the two doctors. Accuracy of teeth length made by CBCT and DPRs were compared to each other. Results For single-rooted premolars, the CBCT measurements underestimated the tooth length at every plane with no statistical significance (P > 0.05), while DPRs measurements overestimated the tooth length significantly (P < 0.05). For two-rooted premolars, the CBCT-APs measurements overestimated the teeth length, but the CBCT-SPs and CBCT-CPs underestimated the teeth length. However, these differences had not statistical significance (P > 0.05). The DPRs measurements underestimated the buccal length but overestimated the palatal length significantly (P < 0.05). There was no statistical significance between the two doctors (P > 0.05). Conclusion CBCT teeth length measurements show a strong correlation with the gold standard at every plane by different doctors, which indicated the high reliability and reproducibility of CBCT measurements.

Periodontitis is a chronic infectious disease in which plaque is the main pathogenic factor. Plaque control and elimination of infection is the primary goal of the treatment for periodontitis. On the basis of plaque control, we could achieve the goal of recovering periodontal tissue function, recovering the physiological morphology of periodontal tissues, and maintaining long-term efficacy to prevent recurrence, so that periodontal tissues remain healthy. This article reported a case of stage III and grade B periodontitis, in which the patient receiving guided biofilm therapy. Guided tissue regeneration combined with bone grafting is performed on residual deep periodontal pockets after controlling of inflammation. Ultimately the patient is satisfied with the results after regular periodontal maintenance.

Chronic periodontitis (CP) is a chronic inflammatory disease characterized by periodontal soft and hard tissue destruction, and the local inflammatory microenvironment runs through all stages of lesions. At present, the common diagnostic criteria for CP include periodontal probing depth, bleeding on probing and evaluation of alveolar bone level by radiographic examination, but there is a lack of accurate assessment of the inflammatory state and the definition of periodontal disease progression. It has been a research hotspot worldwide that how the biomarkers come into wide use to conduct rapid and accurate screening, provide accurate detection information and reliably assess the disease state of CP. Gingival crevicular fluid (GCF) is a serum or inflammatory exudate from periodontium. Its biomarkers are closely related to inflammation and destruction of connective tissue and bone tissue, so they are used to assess the lesions and the evaluation of the therapeutic effect. Thus, this paper reviews the diagnostic value and research progress of GCF biomarkers before and after nonsurgical therapy of CP.

With the continuous development of CAD/CAM technology, more and more CAD/CAM composite ceramic materials are applied to oral prosthetics, whose long-term repair effect depends largely on the bond strength of the prosthesis. The main factor that influences the bond strength between porcelain restoration and tooth is the surface treatment of the restoration. This paper reviews the research progress of surface treatment of CAD/CAM composite ceramic materials.