The Effect of Chin-cup Therapy in Class III Malocclusion: A Systematic Review

The Early Intervention of a Class III Malocclusion With an Anterior Crossbite Using Chincup Therapy: A Case Report

Class III malocclusions with anterior crossbites pose significant challenges in orthodontic treatment, especially in growing children. This case report details the early intervention of a 12-year-old patient presenting with a Class III malocclusion characterized by an anterior crossbite and mandibular prognathism. A chincup was employed to inhibit mandibular growth and encourage maxillary development. Consistent use of the chincup, with regular follow-ups and adjustments, led to significant improvements. The anterior crossbite was corrected, resulting in a Class I molar relationship and an improved facial profile. The maxillary arch perimeter increased, providing space for the eruption of canines and premolars. This case demonstrates that early intervention with a chincup can effectively manage Class III malocclusion with an anterior crossbite, highlighting the importance of timely orthodontic assessment and treatment to achieve stable, long-term results.

Mid-term follow up effectiveness of facemask treatment in class III malocclusion: A systematic review

OBJECTIVE

This systematic review aims to investigate and summarize the mid-term effects and stability of the treatment with facemask appliance.

METHODS

Search without restrictions in five databases (Pubmed, Medline, Embase, Scopus, Cochrane Central Register of Controlled Trials) since inception and hand searching until March 2021 was conducted. Detailed search strategies were based on the PubMed strategy and adapted accordingly. Studies assessing the mid-term effects of facemask appliance, with a follow-up post-treatment period of more than 6 years or after the peak of pubertal growth, were to be included. The risk of bias in individual studies was assessed using the Cochrane guidelines for the RCT and the ROBINS-I tool for the non-RCT studies.

RESULTS

Five studies were finally considered eligible for inclusion (one RCT and four CCTs). According to the reported evidence, the mid-term success rate ranged from 62.7% to 100%. Mid-term success was identified with positive overjet as well as acceptable aesthetic and functional characteristics.

CONCLUSIONS

Class III malocclusion treated with facemask presents a high percentage of success in the mid-term follow-up period. The mid-term effects of facemask were stable for the maxilla, in terms of sagittal and anteroposterior dentoskeletal dimensions, and any kind of relapse is attributed to uncontainable residual growth of the mandible. However, considering the high risk of bias and the follow-up period limitations, more high-quality studies are necessary in order to achieve further clarification. Future research should be based also on identifying biomarkers to indicate likely treatment responses.

REGISTRATION NUMBER

PROSPERO: CRD42020179402.

Posterior Mandibular Displacement-A Systematic Review Based on Animal Studies

Treating extreme mandibular growth is challenging. The mandible is pushed backwards to address itsprotrusion. Nevertheless, conclusions after such displacement in animals have been contradictory. The aim of the present review is to present measurable alterations of the mandible and the condyle following retractionin healthy rats or rabbits. PubMed, Scopus and Web of Science were accessed for relevant studies up to October 2020. Eligibility was determined by the PICOS process, while the risk of bias was estimated with SYRCLE's risk of bias tool. Retraction resulted in a more distal molar occlusion and the condyle rested more posteriorly. Mandibular anteroposterior bilateral growth restriction was achieved, the condylar process measured smaller and its angulation increased. The condylar neck thickened, its posterior surface flattened, the coronoid process was measured longer, and enlarged retromolar density was registered. Differences in the ramus height and the intercondylar distance were insignificant. Changes persisted for the period of study and subsequently the mandible resumed its inherited growth pattern. The timing of mandibular shaping and TMJ outcomes might depend on the properties of the applied force. Stability is of concern and well-structured, long-term studies are expected to resolve the issue and further clarify the results of posterior mandibular displacement.

Study of changes in rat mandibular condyle under intermittent cyclic and continuous compressive stress

OBJECTIVES

This study aimed to investigate the effects of intermittent and continuous compressive stress on rat mandibular condyles.

DESIGN

Ninety rats were randomly divided into 5 groups: non-loading control groups and 1-day intermittent cyclic loading, 3-day intermittent cyclic loading, 7-day intermittent cyclic loading, continuous loading groups. In the loading groups, compressive mechanical stresses were loaded onto the condyles. The rats were euthanized after one, two, or four weeks. Histomorphometric and immunochemical staining of the cartilage and the micro-CT scanning of subchondral bone were investigated.

RESULTS

Under continuous loading following the first week, cartilage thickness, numbers of chondrocytes, extracellular matrix (Type-II collagen) and proliferation decreased significantly, and there was no apparent repair response after the second and fourth weeks. The cartilage of 1-day and 3-day intermittent cyclic loading groups showed similar pathological changes but better proliferative activity compared with the continuous loading group. The 7-day intermittent loading group had significant recovery after 2 weeks, including the increase of cartilage thickness and the number of chondrocytes, cell swelling and rearranging. However, the remodeling of subchondral bone showed no significant difference between the intermittent and continuous loading stress compared to the control group.

CONCLUSIONS

Under moderate mechanical stress, the condylar cartilage actively remodeled, whereas the subchondral bone, as supportive rigid structure, was less sensitive to mechanical pressure. The intermittent compressive stress protects the condylar cartilage from excessive damage, which is different from continuous compressive stress. With longer intervals, the cartilage has the potential capability for recovery as the initial state.

Oral health related quality of life of patients with class III skeletal malocclusion before and after orthognathic surgery

BACKGROUND

Orthognathic surgery includes improvement of morphology and function of occlusion as well as psychological perception and oral health-related quality of life (OHRQoL) of patients. The aim of this study was to determine the OHRQoL of patients with class III skeletal malocclusion before and after orthognathic surgery.

MATERIALS AND METHODS

A total of 112 skeletal class III patients including 39 (34.8%) males and 73 (65.2%) females participated in this descriptive quasi-experimental study in three groups: "prior to orthodontic treatment" (n = 25); "under orthodontic treatment and prior to surgery" (n = 65), and "after surgery" (n = 25). All patients filled out a demographic information questionnaire, the oral health impact profile-14 (OHIP-14), and the orthognathic quality of life questionnaire (OQLQ) under the supervision of the examiner. Data were analyzed using ANOVA, independent samples t-test, Mann Whitney test, and Kruskal-Wallis test.

RESULTS

OHRQoL summary score changed from 14.5 prior to orthodontic treatment to 23.4 prior to surgery and during orthodontic treatment to 5.4 after surgery. These OHRQoL changes were statistically significant (P < 0.001).

CONCLUSIONS

Orthognathic surgery matters to patients with class III skeletal malocclusion and significantly improves their OHRQoL.

An asymmetric magnetic reverse Twin-block applian ce for the treatment of a skeletal Class III malocclusion: a case report

Background

The treatment of a skeletal Class III malocclusion with accompanying mandibular asymmetry is an orthodontic challenge. A skeletal Class III may be associated with a retrognathic maxilla, a prognathic mandible and a mandibular asymmetry can be of dental or skeletal origin or in various combinations. Timely treatment with appropriate biomechanics is crucial for an acceptable and stable result.

Aims

The aim of this article was to introduce a clinically effective asymmetric magnetic reverse Twin-block appliance (AMRTB) for growth modification treatment of an 11-year-old girl who presented with a skeletal Class III malocclusion and accompanying mandibular asymmetry.

Methods

The treatment was comprised of two phases, the first of which was growth modification using the AMRTB for the stimulation of maxillary growth, restraint of mandibular growth, and improvement of the mandibular asymmetry. This was followed by a second phase involving full fixed appliances to optimise the interdigitation and occlusion.

Results

The skeletal Class III relationship and mandibular asymmetry was successfully corrected after two years of treatment. A good facial appearance and pleasing smile aesthetics were achieved. The treatment result was stable after six years of follow-up.

Conclusion

This case demonstrated that the AMRTB was a clinically effective appliance for growth modification treatment in patients with a skeletal Class III malocclusion and mandibular asymmetry.

Developing Class III malocclusions: challenges and solutions

Class III malocclusion represents a growth-related dentofacial deformity with mandibular prognathism in relation to the maxilla and/or cranial base. Its prevalence varies greatly among and within different races, ethnic groups, and geographic regions studied. Class III malocclusion has a multifactorial etiology, which is the expression of a moderate distortion of normal development as a result of interaction between innate factors or genetic hereditary with environmental factors. Various skeletal topographies of underlying Class III malocclusion are due to discrepancy in the maxillary and mandibular growth along with vertical and/or transverse problems apart from sagittal malformations. The spectrum of complications for Class III malocclusion ranges in gravity from dentoalveolar problems with functional anterior shift of the mandible to true skeletal problems with serious maxillomandibular discrepancies, which makes its diagnosis highly challenging in growing children. Concern regarding early treatment and the need for interceptive care in the case of Class III malocclusion has always been a dilemma, knowing that not all problems will be solved in these cases until maxillomandibular growth is further completed, and the long-term outcome of various treatment approaches may depend on the growth tendency of an individual. Interceptive treatment of Class III malocclusions should be undertaken if it prevents damage to the oral tissues and/or significantly reduces the amount or severity of future orthodontic and surgical interventions. This paper presents an overview of developing Class III malocclusion, with the emphasis on challenges and their solutions based on the best current available evidence.