The content of the guidelines is based on monographs and literatures on the clear aligner orthodontic treatment in the past five years, and the clinical consensus of all the members of Expert Group for Writing Project of Clear Aligner Technology. This guidelines provide guidance and reference for orthodontists who want carry out clear aligner orthodontic treatment in three parts: overview, diagnosis and design, and common treatment strategies. In the part of the overview, the instructions for the preparation of this guide were described. The requirements for practitioners providing clear aligner orthodontic treatment were put forward, and the risks associated with clear aligner orthodontic treatment were suggested. In the part of diagnosis and design, the indications and selection of clear aligner orthodontic treatment were defined. The requirements of collecting data in orthodontic cases and the design process of clear aligner orthodontic treatment were also explained. The present common treatment strategies for clear aligner orthodontic treatment were summarized in the third part of the guidelines. The elaboration of the treatment methods such as distalization of molar, interproximal enamel reduction and stepwise tooth movement were explained.
Dental Care ; Humans ; Molar ; Orthodontic Appliances, Removable ; Tooth Movement Techniques

OBJECTIVES: At present, the research on clear aligner of molar distalization mainly focuses on the upper jaw, while the research on mandibular molars is few.This study aims to evaluate the therapeutic effect of mandibular molars distalization with clear aligner via cone beam CT (CBCT) and Dolphin software. METHODS: Twenty cases of mandibular molars with clear aligner were included according to the inclusion and exclusion criteria. CBCT was taken before treatment (T0) and when the first molar was moved in place (T1). Dolphin software was used to measure the effectiveness of molar distalization. Three-dimensional changes in direction and the impact on the incisors and facial soft and hard tissues were evaluated. RESULTS: The effective rates of crown and root distalization of the second and first mandibular molars were 74%, 49%, and 71%, 47%, respectively. The second and first molars were both the distal buccal cusp with the largest distalization [(2.15 ± 0.91) mm and (1.85±1.09) mm], respectively, with significant difference between the T0 and T1 ( CONCLUSIONS Clear aligner can effectively move mandibular molars farther, the crown is more effective than the root, and it is tilted. The second mandibular molar is more effective than the first mandibular molar in its distant displacement and three-dimensional changes. Molar distalization causes minor changes in mandibular incisors and facial soft and hard tissues.
Cephalometry ; Maxilla ; Molar ; Orthodontic Appliances, Removable ; Tooth Movement Techniques

OBJECTIVES: This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group. METHODS: PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis. RESULTS: Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group. CONCLUSIONS The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.
Humans ; Malocclusion, Angle Class II/therapy* ; Mandibular Advancement ; Orthodontics, Corrective ; Orthodontic Appliances, Functional ; Mandible ; Orthodontic Appliances, Removable ; Cephalometry

OBJECTIVES: This study aimed to investigate the accuracy of model superimposition and automatic analysis for upper and lower dentition widths in iTero Progress Assessment during the clear aligner process. METHODS: Nineteen cases were included in this retrospective case control study. Pretreatment dental cast (T0) and post treatment dental cast after staged treatment (T1) were available for three-dimensional (3D) model superimposition. The movements of maxillary teeth in the horizontal plane (cross section) after staged treatment and the widths of upper and lower dentitions were measured by 3D model superimposition in real world and iTero Progress Assessment. The data collected from the two methods were compared. RESULTS: The movements [Median (upper and lower quartiles)] of maxillary teeth in the horizontal plane after staged treatment were 2.31 (1.59, 3.22) and 1.79 (1.21, 3.03) mm in iTero Progress Assessment and 3D model analysis, respectively. Significant difference was observed between the two groups (P<0.05). In the measurement of upper and lower dentition width, four indicators were measured, including intercanine width upper, intermolar width upper, intercanine width lower, and intermolar width lower. Before treatment, the measurement of iTero Progress Assessment were (35.78±2.49), (56.21±2.51), (27.43±1.38), (52.26±2.91) mm, respectively, and actual measurement were (35.77±2.53), (56.17±2.47), (27.40±1.41), (52.30±2.86) mm, respectively, without significant difference (P>0.05). After stage treatment, the measurement of iTero Progress Assessment were (37.37±2.86), (57.76±2.56), (28.89±2.00), (54.16±2.19) mm, respectively, and actual measurement were (37.29±2.94), (57.71±2.63), (28.88±2.05), (54.01±2.15) mm, respectively, and there was no significant difference (P>0.05). CONCLUSIONS The data from iTero Progress Assessment did not coincide with the model superimposition results with palate as reference. The accuracy of model superimposition in iTero Progress Assessment needs further investigation, whereas the arch width analysis is accurate. Therefore, iTero Progress Assessment results should be interpreted with caution by orthodontists in clinical applications.
Case-Control Studies ; Cuspid ; Dental Arch ; Orthodontic Appliances, Removable ; Retrospective Studies ; Humans

OBJECTIVES: This study aimed to construct the finite element model of the mandibular first molar with the invisible appliance and explore the dentition movement characteristics of the mandibular first molar when using micro-implant anchorage and different initial positions of the first molar. METHODS: Models of the mandible, tooth, periodontal membrane, and invisible appliance were constructed using cone beam computed tomography (CBCT) data. The two groups were divided into the non-anchorage group and the micro-implant group (between the roots of the first molar and the second molar) based on whether the elastic traction of the micro-implant was assisted or not. The two groups were divided into the following conditions based on the starting position of the first molar: Working condition 1: the distance between the first molar and the second premolar was 0 mm; working condition 2: the distance between the first molar and the second premolar was 1 mm; working condition 3: the distance between the first molar and the second premolar was 2 mm; working condition 4: the distance between the first molar and the second premolar was 3 mm. The data characte-ristics of total displacement and displacement in each direction of dentition were analyzed. RESULTS: In the non-ancho-rage group, all the other teeth showed reverse movement except for the first molar which was moved distally. Meanwhile, in the micro-implant group, except for a small amount of mesial movement of the second molar in wor-king condition 1, the whole dentition in other working conditions presented distal movement and anterior teeth showed lingual movement, among which the distal displacement of the first molar in working condition 4 was the largest. With the change of the initial position of the first molar to the distal, the movement of the first molar to the distal, the premolar to the mesial, and the anterior to the lip increased, while the movement of the second molar to the mesial decreased. CONCLUSIONS The micro-implant can effectively protect the anterior anchorage, increase the expression rate of molar distancing, and avoid the round-trip movement of the second molar. The initial position of the first molar movement is related to the amount of distancing and the remaining tooth movement.
Finite Element Analysis ; Molar ; Bicuspid ; Periodontal Ligament ; Tooth Movement Techniques/methods* ; Orthodontic Appliances, Removable

OBJECTIVETo introduce a new modified twin-block advancement appliance and investigate the effects on respiratory variables in patients with OSAS.

METHODS29 patients with OSAS participated in the study and were fitted with modified twin-block appliances to hold the mandible in an anterior and inferior position. Polysomnography was performed with and without appliance insertion. And questionnaires were used for registration of patients subjective symptoms. Pair-t analysis was used to evaluate the effects of appliances in patients with OSAS.

RESULTS26 patients responded to the appliance therapy. Apnea-hypopnea index, apnea index and hypopnea index were reduced significantly (P < 0.01). Lowest arterial oxygen saturation improved significantly (P < 0.01). Discomfort with mandibular advancement disappeared within one week.

CONCLUSIONSModified twin-block advancement appliance is a conservative, successful treatment alternative that could benefit patients suffered from OSAS.

Adult ; Female ; Humans ; Male ; Middle Aged ; Orthodontic Appliance Design ; Orthodontic Appliances, Removable ; Sleep Apnea, Obstructive ; physiopathology ; therapy ; Treatment Outcome

OBJECTIVEObserve the clinical effect of removable lingual arch plus auxiliary spring for convenient dental (especially mandibular) arch expansion.

METHODSSeventeen patients with dental arch constriction complicated by mild dental crowding were enrolled in this study, including 9 requiring maxillary arch expansion and 8 necessitating mandibular expansion. The patients were divided to two groups at random for arch expansion with removable lingual arch plus auxiliary spring and with Quad-helix, respectively, and the effect of arch expansion was compared between the two groups.

RESULTSAfter 8 weeks of arch expansion, the average width of U4-U4 and U5-U5 in removable lingual arch group was enlarged by 2.2 mm and 3.0 mm, and that in Quad-helix group by 2.3 mm and 3.5 mm, respectively, showing no significant differences between the two groups (P>0.05). After 12 weeks of treatment, the average width of L4-L4 and L5-L5 in the former group was enlarged by 2.3 mm and 2.5 mm, respectively, significantly greater than that in the latter group (1.0 mm and 1.2 mm, P<0.05).

CONCLUSIONRemovable lingual arch plus auxiliary spring allows significant expansion of the middle segment of the dental arch (bicuspids), and can be more effective than Quad-helix for mandibular arch expansion.

Adolescent ; Child ; Dental Arch ; pathology ; Humans ; Malocclusion ; therapy ; Orthodontic Appliances, Removable ; Orthodontics, Corrective ; methods ; Palatal Expansion Technique ; instrumentation ; Young Adult

Adult ; Cephalometry ; Humans ; Male ; Mandible ; Mandibular Advancement ; instrumentation ; methods ; Orthodontic Appliances, Removable ; Polysomnography ; Radiography ; Sleep Apnea, Obstructive ; diagnosis ; diagnostic imaging ; therapy

OBJECTIVETo observe the whole process of cranio-maxillofacial development of an animal model with bilateral premaxillary clefts, after being exerted with premaxillary retro-pressing forces.

METHODSExperimental rabbits with premaxillary clefts and without clefts were exerted with retro-pressing forces respectively. Roentgenographic cephalometric analysis and different investigations of premaxillary suture were performed during the whole craniofacial development.

RESULTSThe longitudinal cephalometric analysis showed that a temporary retarding effect of mid-facial growth existed. The hindrance of maxillary growth potentiality did not occur in spite of being exerted retro-pressing force as to this experimental extent.

CONCLUSIONS(1) Infant rabbit combined with the designed retro-pressing appliance is an ideal experimental model for quantitative study of active orthopedic treatment of protruding premaxilla. (2) Using active preoperative orthopedics to reposit the protruding premaxilla of bilateral cleft palate is a reasonable and effective approach.

Animals ; Cephalometry ; Cleft Lip ; physiopathology ; therapy ; Cleft Palate ; physiopathology ; therapy ; Female ; Maxilla ; growth & development ; Maxillofacial Development ; physiology ; Models, Animal ; Orthodontic Appliances, Removable ; Rabbits

Occlusal-maxillo-facial structural change of crossbite malocclusion after orthodontic therapy by modified ACTIVATOR appliance was investigated. Eighty crossbite cases of deciduous dentition and mixed dentition were treated by modified ACTIVATOR. Through pre- and post-treatment analysis of stone model, Schuller's position X-ray and craniofaciometrics, the change in craniofacial length, width and height in early-phase crossbite malocclusion was studied. The results showed that there was no significant change in the width of maxillary and mandibular dental arch. Maxillary length and protrusion was increased significantly, upper incisors slopped labially. The lower incisors slopped lingually, mental angle decreased more severely. The lower and posterior facial height was increased to normal level.
Cephalometry ; Child ; Child, Preschool ; Dental Arch ; anatomy & histology ; Dental Stress Analysis ; Dentition, Mixed ; Female ; Humans ; Male ; Malocclusion ; therapy ; Maxilla ; anatomy & histology ; growth & development ; Orthodontic Appliances, Removable ; Orthodontics, Corrective ; instrumentation ; Orthodontics, Interceptive ; instrumentation ; Tooth, Deciduous