OBJECTIVES: To evaluate the effects of a Twin-block appliance on the condyles of patients with ClassⅡmalocclusion by conducting a systematic review and a Meta-analysis. METHODS: Pubmed, Embase, Cochrane Library, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and VIP Database were electronically searched. Randomized controlled trials, controlled clinical trials, and single-arm trials on condylar changes produced by a Twin-block appliance in patients with ClassⅡmalocclusion were included. Two reviewers independently extracted and assessed the risk of bias. Meta-analyses were conducted with Review Manager 5.3. RESULTS: Eight studies were included; among which, seven were of high quality. After treatment with a twin block appliance, condyles moved anteriorly. The anterior joint spaces decreased (P<0.000 01), whereas the posterior spaces increased (P<0.000 01). The superior spaces were not changed (P=0.11). Moreover, a significant difference was observed in the increase of the condylar space index (P<0.000 01). After treatment, the anteroposterior diameters of the condyles and condylar height increased (P=0.000 2 and P<0.000 01, respectively). By contrast, no significant changes were discovered in the medial external diameters of the condyles (P=0.42). CONCLUSIONS A Twin-block appliance can promote the growth of a condyle in the posterior and upper direction and move it forward in favor of the correction of Class Ⅱ malocclusion.
Humans ; Malocclusion, Angle Class II/therapy* ; Temporomandibular Joint ; Bone and Bones ; China ; Orthodontic Appliances, Functional ; Cephalometry

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

In recent years, the early orthodontic treatment of malocclusion has become a hot issue in the field of orthodontics. Some new phenomena and new problems that have emerged require in-depth analysis and discussion, and need to be given correct guidance and norms. Malocclusion refers to the deformities of teeth, jaws, and craniofacial bones caused by genetic and environmental factors during growth and development. Based on the accurate judgment of the etiology and diagnosis, choosing the right time and suitable indications, with the advantage of growth and development, the most suitable appliance can be selected in the early stage of malocclusion to fix malocclusion, and to effectively prevent and block the formation and development of malocclusion. This article will discuss how to timely and appropriately carry out the early prevention and treatment of malocclusion with six aspects, including methods of performing early orthodontic treatment, the basis and guarantee of early orthodontic treatment, correctly understanding early orthodontic treatment, the issues that should be paid attention to in carrying out early orthodontic treatment, actively advocating multidisciplinary cooperation during early orthodontic treatment and understanding face management in a serious way.
Dental Care ; Humans ; Malocclusion/therapy* ; Malocclusion, Angle Class II/therapy* ; Orthodontic Appliances, Functional ; Orthodontics, Corrective/methods*

OBJECTIVEThis study assessed the effects of two-phase treatment with Herbst appliance on the bony structure of the temporomandibular joint via cone beam computed tomography (CBCT) analysis.

METHODSThis study selected 15 patients exhibiting early permanent dentition and classⅡmalocclusion combined with mandibular retrusion treated by a two phase treatment (Herbst and fixed appliance). The CBCT scans of the patients were obtained at the following stages: 2 weeks before Herbst treatment (T1), at the start of treatment when the Herbst appliance was set in place (T2), immediately after removal of the Herbst appliance (T3), and immediately after removal of the edgewise appliance (T4). Three-dimensional reconstruction and related measurements were performed using InvivoDental software, and the acquired data were statistically analyzed.

RESULTS1) CBCT showed a crescent-shaped hyperplasia at the posterior-superior border of the condyles that the outer edge was highly dense and the inner region was lowly dense in T3 in 14 patients (28 condyles). 2) In T3-T2 and T4-T1, the diameters of the anteroposterior condyles increased by 0.62 and 0.66 mm, respectively (P<0.01), and the condylar head height correspondingly increased by 0.54 and 0.53 mm (P<0.01).

CONCLUSIONSCondylar growth remodeling occurs during Herbst treatment.
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Bone and Bones ; Cone-Beam Computed Tomography ; Humans ; Orthodontic Appliances, Functional ; Retrognathia ; Temporomandibular Joint

OBJECTIVETo investigate the outcome of skeletal Class Ⅲ patients treated with Fränkel function regulator type Ⅲ (FR Ⅲ)in the early mixed and late mixed dentition.

METHODSThe samples consisted of 45 mild and moderate skeletal Class Ⅲ patients(26 males, 19 females; meanage, [7.9±1.3] years) treated with FR Ⅲ. According to Hellman's dental developmental stages, these samples were divided into early-treated group(n=24) and late-treated group(n=21). Lateral cephalograms were taken at the beginning and the end of treatment. Twenty-one measurements on hard and soft tissue were included.

RESULTSAfter treatment, SNA, ANB, NA-Apo, Wits, U1-SN, U1-NA, Overjet, UL-EP were significantly increased (1.0±1.9)°, (1.2±1.6)°, (2.6±4.2)°, (1.8±2.7) mm, (4.2±7.6)°, (2.6±7.5)°, (3.6±2.3) mm and (0.8±2.2) mm(P<0.05). OP-SN and IMPA were significantly decreased (1.5±3.7)°and (1.4±4.2)°(P<0.05). There were significant differences in SNA, ANB, UL-EP, IMPA, L1-NB between early-treated group and late-treated group(P<0.05).

CONCLUSIONSFR Ⅲ was suitable for the treatment of mild and moderate skeletal Class Ⅲ patients. The result was better in the early-treated patients than in late-treated ones.

Cephalometry ; Child ; Dentition, Mixed ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; therapy ; Orthodontic Appliances, Functional ; Overbite ; etiology ; Time-to-Treatment ; Treatment Outcome

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*

OBJECTIVETo observe the changes of bone histomorphometry parameters in condyle of rabbits during mandibular forward positioning.

METHODSForty rabbits with eight weeks of age were simple randomly divided into the experimental group (n = 24) and control group (n = 16).Mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance.The experimental group and control group were sacrificed after 2 and 4, 8, 12 weeks.The specimens from right tempromandibular joints were processed for undemineralised sections.These sections were used for fluorescent microscopy observation and the measurement of bone histomorphometry.

RESULTSAt 8 week bone-volume fraction [(75.83 ± 1.10)%], trabecular thickness [(103.28 ± 2.89) µm], trabecular number [(2.86 ± 0.06) mm(-1)], mineral apposition rate [(2.32 ± 0.02) µm/d] and index of osteoblast [(30.20 ± 0.47) N/mm(2)] in subchondral region of the cartilage in the experimental group were significantly increased compared with the age-matched controls [respectively (64.00 ± 1.54)%, (87.00 ± 1.13) µm, (1.84 ± 0.08) mm(-1), (1.69 ± 0.02) µm/d and (21.07 ± 0.59) N/mm(2)] (P < 0.05). However, trabecular separation [(170.00 ± 2.25) µm] was lower than those in the controls [(241.50 ± 1.57) µm] with significant difference(P < 0.05). There was no significant difference in the bone histomorphometry parameters of the central region between the experimental group and the age-matched control group (P > 0.05).

CONCLUSIONSThe pattern of bone histomorphometry parameters expression in subchondral region has a high correlation with the adaptive remodeling of the condyle after functional appliance.

Animals ; Cartilage ; anatomy & histology ; growth & development ; Female ; Male ; Mandibular Advancement ; Mandibular Condyle ; anatomy & histology ; growth & development ; Orthodontic Appliances, Functional ; Rabbits ; Random Allocation

OBJECTIVETo evaluate the effects of angle Class II division 2 malocclusion treated with Herbst appliance in young adults.

METHODSCast splint Herbst appliance and multi-bracket appliance were used to treat 12 patients with Class II division 2 malocclusion aged from 16 to 25 years old. The lateral cephalograms were measured with Winceph 8.0 software and statistical analysis was carried out by SPSS 13.0 software.

RESULTSThe changes in SNA, Co-Go, Go-Po after treatment had no statistical significance (P>0.05). The SNB increased and ANB decreased after treatment. Upper and lower incisors labially inclined and inter-incisor angle increased. Upper posterior teeth had distal movement, lower posterior teeth had mesial movement and extrusion. Mandibular plane angle and occlusal plane angle had clockwise rotation. The overbite decreased significantly, and the molar relationship changed from Class II to Class I in all patients.

CONCLUSIONHerbst appliance combined with multi-bracket appliance can be used effectively for correcting Class II division 2 malocclusion in young adults.

Adolescent ; Adult ; Cephalometry ; Female ; Humans ; Incisor ; Malocclusion, Angle Class II ; Mandible ; Orthodontic Appliances, Functional ; Young Adult

OBJECTIVETo examine the hypothesis that functional appliances enhance mandibular growth in the treatment of skeletal Class II malocclusion.

METHODSA literature search was performed in electronic databases according key words "skeletal Class II malocclusion" , and full texts of selected articles were collected by hand-made method. The data were extracted from the articles. The quality of the trials was evaluated and meta-analysis method was used to analyze the data through RevMan 4.2.

RESULTS19 articles could be qualified for the final analysis. Those indices including SNB (Activator, Twin-block, Herbst group), Go-Gn, Co-Pg, Co-Gn, Co-Go, demonstrated significant effect of functional appliances on mandibular growth in comparing with those of untreated control group. There were no significant differences between the two groups for the indicies of SNB (Fränkel-II) and Go-Me.

CONCLUSIONFunctional appliances can enhance mandibular growth in treatment of skeletal Class II malocclusion. This mainly dues to the growth of the ramus instead of changes of mandibular body length.

Cephalometry ; Humans ; Malocclusion ; Malocclusion, Angle Class II ; Mandible ; Orthodontic Appliances, Functional

OBJECTIVETo evaluate whether there was any difference on the clinical effects of Twin-block, Activator and Herbst appliances on the clinical effects of growing children with skeletal Class II malocclusion.

METHODS60 patients with skeletal Angle Class II malocclusion were divided into three groups (Twin-block group, Activator group, Herbst group), 20 in each group. The patients of three groups were respectively treated by Twin-block, Activator and Herbst appliances. The patients were 10-13 years old(mean 11.6) before treatment, and were mainly with mandibular retrognathia. Data of pre- and post-treatment were measured and analyzed.

RESULTSThere was statistically significance of ANB, SNB, Go-Gn, Co-Gn, L1-MP in sagittal changes, and N-Me, ANS-Me, S-Go, SN-MP, Co-Go in vertical changes after treatment of three groups. Herbst group was more effective than Twin-block group and Activator group in the increase of L1-MP, but the effects on maxilla were not significant among them. There was no statistical significance of Ptm-A, OB, N-Me, ANS-Me, S-Go and Co-Go between 3 groups.

CONCLUSIONTreatment effects of three different functional appliances (Twin-block, Activator and Herbst) are similar in the early treatment of skeletal Class II malocclusion. Compared with Twin-block and Activator, Herbst has more effects on orthopedic of mandibular and lower anterior teeth.

Adolescent ; Cephalometry ; Child ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; Mandible ; Maxilla ; Orthodontic Appliances, Functional