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 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

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

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

OBJECTIVE: To assess the efficacy of bone anchorage and maxillary facemask protraction devices in treating skeletal class Ⅲ malocclusion in adolescents. METHODS: Articles relating to the use of bone anchorage and maxillary facemask protraction devices for treating skeletal class Ⅲ malocclusion in adolescents were searched from the databases of Cochrane Library, PubMed, EmBase, CNKI, and Wanfang database. Several inclusion and exclusion criteria were developed for the article screening. The clinical data were extracted, and the quality of the selected articles was evaluated. A Meta-analysis of SNA, SNB, ANB, ANS-Me, Wits, and U1-PP change was performed by using RevMan 5.3. RESULTS: Seven studies (264 patients) were included in the Meta-analysis. Among these studies, three were randomized controlled trials, and four were non-randomized controlled trials. Compared with the maxillary facemask protraction device group, the bone ancho-rage device group had higher SNA changes and lower ANS-Me, Wits, and U1-PP changes (P<0.05). No significant differences were observed in the SNB and ANB changes between these two groups. CONCLUSIONS Compared with the maxillary facemask protraction device, the bone anchorage device can increase the extent of protraction of the maxilla and has better controls for the labial inclination of the maxillary anterior teeth in treating skeletal class Ⅲ malocclusion among adolescents. However, additional high-quality randomized controlled trials must be performed to verify the results.
Adolescent ; Cephalometry ; Extraoral Traction Appliances ; Humans ; Malocclusion, Angle Class III ; Maxilla ; Palatal Expansion Technique

OBJECTIVE: The aim of this study was to evaluate long-term changes in the pharyngeal airway dimensions after functional appliance treatment in adolescents with skeletal Class II malocclusions. METHODS: Pharyngeal airway dimensions were compared between subjects with skeletal Class II malocclusions (n = 24; mean age: 11.6 +/- 1.29 years) treated with a Class II bionator and age-matched control subjects with skeletal Class I occlusions (n = 24; mean age: 11.0 +/- 1.21 years) using a series of lateral cephalograms obtained at the initial visit (T0), after treatment (T1), and at the completion of growth (T2). RESULTS: The length of the nasopharyngeal region was similar between adolescents with skeletal Class I and Class II malocclusions at all time points, while the lengths of the upper and lower oropharyngeal regions and the pharyngeal airway areas were significantly smaller in the skeletal Class II adolescents before treatment when compared to the control adolescents (p < 0.05). However, following treatment with a functional appliance, the skeletal Class II adolescents had increased pharyngeal airway dimensions, which became similar to those of the control subjects. CONCLUSIONS: Functional appliance therapy can increase the pharyngeal airway dimensions in growing adolescents with skeletal Class II malocclusions, and this effect is maintained until the completion of growth.
Activator Appliances* ; Adolescent* ; Humans ; Malocclusion*

Child ; Extraoral Traction Appliances ; Humans ; Molar ; Orthodontic Wires ; Orthodontics, Interceptive ; instrumentation ; Prognosis ; Time Factors ; Tooth Crown ; surgery ; Tooth Eruption, Ectopic ; surgery ; therapy ; Tooth Movement Techniques ; instrumentation ; methods

OBJECTIVETo evaluate the soft profile and hard tissue changes after maxillary protraction with skeletal anchorage implant in treatment of Class III malocclusion during growth period.

METHODS18 patients with skeletal Class III malocclusion were treated with maxillary protraction for about 9 months, (3.5 +/- 0.1) N, with skeletal anchorage implant and face mask. Cephalometric records were analyzed to assess the changes of maxillo-facial structure of the hard and soft tissue before and after treatment.

RESULTSAll patients' Class III profiles were corrected. Maxillary growth increased, chin clockwise rotated, facial convexity angle increased, lower lip protrusion decreased. Facial vertical height ratio, nasolabial angle, upper lip protrusion and mentolabial sulcus changed unconspicuously. Upper incisors kept in sites, lower incisor upright, maxilla moved forwards. SNA, ANB significantly increased. SNB decreased and the mandible clockwise rotated.

CONCLUSIONThe maxilla is effectively protracted without significant rotation by using skeletal anchorage implant. The undesired effects of conventional protraction therapies, such as labial tilt of upper anterior teeth and extrusion of the maxillary molars, are reduced or eliminated with skeletal anchorage implant. These effects can conspicuously correct profiles of the patients with skeletal Class III malocclusion, make the profile more harmonious and aesthetic.

Cephalometry ; Chin ; Extraoral Traction Appliances ; Face ; Humans ; Incisor ; Lip ; Malocclusion, Angle Class III ; Mandible ; Maxilla ; Molar

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