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.

Orthodontic treatment for dentofacial deformity is fundamental throughout the entire management process of cleft lip and palate. Orthodontist is one of those who are indispensable in the comprehensive multidisciplinary cleft team. Cleft lip and palate patients have unique dentofacial characteristics which makes the treatment goals and strategies different from those of other patients in different stages. For newborns with cleft lip and palate, the main treatment includes presurgical orthopedics. For patients in their primary dentition stage, the treatment mainly focuses on the prevention of bad oral habits and severe malocclusion. For those in their mixed dentition stage, the treatment mainly consists of dentition preparation for alveolar bone grafting and skeletal growth modification. For patients in their permanent dentition stage, treatment strategies include orthodontic camaflouge treatment, combined orthodontic-orthognathic approach and segmental alveolar distraction osteogenesis. In addition to routine orthodontic treatment, orthodontists should pay special attention to managing the compliance of cleft lip and palate patients with unique psychological characteristics. By summarizing the state-of-art cleft lip and palate orthodontic care in the multidisciplinary team, this review aims to involve more orthodontic clinicians to join in the modern biopsychosocial medical practice of cleft lip and palate team approach and to improve the standard of care for cleft lip and palate patients.

Transverse maxillary deficiency is a common malocclusion in the clinic. Palatal expansion techniques are commonly used in the treatment of maxillary transverse deficiency. Traditional palatal expansion techniques have good effects on the treatment of children and adolescents whose palatal suture has not yet closed, but the effects on adult patients are unsatisfied. New palatal expansion techniques, such as miniscrew-assisted rapid palatal expansion and surgical-assisted maxillary expansion, have increased the age-related indications for palatal expansion, and their bone expansion effect has been strengthened. With the development of CAD/CAM technology and 3D printing technology, techniques such as Invisalign and personalized appliances have been developed and have promising application prospects. To provide references for the clinical treatment of maxillary transverse deficiency, palatal expansion techniques are reviewed from the following aspects: mechanism and indications, expansion pattern, traditional and new palatal expansion appliances, stability and retention of palatal expansion, outlook of future expanders, etc.

Eye tracker is an instrument that can record the characteristics of eye movement when people process visual information. This instrument is important for basic psychological research. In the study of dental aesthetics, an eye tracker reflects the observer′s objective eye movement pattern and reveals the underlying aesthetic psychology. This paper summarizes the major research methods of dental aesthetics while focusing on eye-tracking studies in oral aesthetics. Eye tracking studies show that different population has different eye movement patterns when observing the same faces, while the same population can have different eye movement patterns when observing the faces of dental patients and normal people. This finding reveals that the personal characteristics and experience, the social environment and the featured facial structure of the observed individuals can influence eye movement patterns. This study also shows the factors that cause the aesthetic differences among different individuals and groups, as well as the psychological mechanisms.

The rapid development of digital technology has made the processes of orthodontic data collection, diagnosis, design and treatment more accurate, comprehensive, convenient and safe and has improved the clinical efficiency of orthodontists. Safe, non-invasive, rapid three-dimensional facial imaging and digital dental models have enabled orthodontists to collect accurately visualized case data. In addition, during diagnosis and design, orthodontists can comprehensively analyze teeth, jaws, and cranial surfaces in 3 dimensions. Through advances that range from digitized whole-dentition information to computer-replicated design and computer-aided manufacturing, invisible orthodontic technology without brackets has become one of the best manifestations of the combination of digital technology and oral orthodontics. In addition, individualized fixed orthodontic devices have become widely used in orthodontic clinics. In this paper, the applications of digital technology in orthodontic clinics is described. It is hoped that orthodontists will be able to use digital technology rationally to benefit increasing numbers of patients with orthodontic demands.

Increasing numbers of adult patients are seeking orthodontic treatment, which increases the need for orthodontists to treat malocclusion in periodontally compromised teeth affected by periodontitis. It is essential to control active inflammation prior to initiating an orthodontic protocol to avoid further breakdown of alveolar bone caused by periodontitis. However, whether the condition of periodontal ligaments can completely recover to a normal condition after controlling inflammation and tolerate orthodontic tooth movement remains controversial. The present review elaborates, from clinical trials (macroscopic) to biological tests (microscopic), the characteristics of periodontal tissue and periodontal ligament cells with a history of periodontitis that are submitted to orthodontic force loading. The following conclusions are made: 1. Orthodontic treatment in periodontally compromised patients is unusual because of changes in periodontal condition. 2. The combination of orthodontic force loading and uncontrolled periodontal inflammation aggravates pathological bone resorption; therefore, it is crucial to perform periodontal therapy prior to orthodontic treatment. 3. The periodontal ligament can withstand proper mechanical force loading after periodontal treatment. 4. Orthodontic treatment, as an adjunctive therapy, can improve periodontally compromised tissue and pathological tooth movement.

Recently, corticotomy-assisted orthodontic treatments have gathered increasing clinical attention and have been applied more frequently. This technique evolved from traditional corticotomies on the buccal and palatal sides to buccal flapless corticotomies. Accumulating clinical studies suggest that this method leads to accelerated tooth movement, augmented alveolar bone and improved periodontal tissue health. This paper provides an overview of the development of this surgical technique and clinical research results.