An assessment of skeletal and dental responses to the functional magnetic system (FMS)

280 mT static magnetic field promotes the growth of postpartum condylar cartilage

PURPOSE

Functional appliances made of permanent magnets have been used in jaw orthopedic treatment. However, whether the static magnetic field (SMF) generated by permanent magnets promotes the developmental sequence of condylar cartilage and thus promotes the growth of the mandible remains to be studied. The aim of this study was to investigate the effects of 280 mT SMF on postnatal condylar chondrogenesis and endochondral ossification and the roles of FLRT3, FGF2 and BMP2 signaling in this chondrodevelopmental sequences.

METHODS

Forty-eight rats were assigned to two groups (control and SMF). The condyles were collected at the specified time points. The histomorphological changes in the condyle were observed by histological staining. The expression of proteins related to the proliferation and differentiation of the condylar cartilage and the changes in subchondral bone microstructure were analyzed by immunohistochemical staining and micro-CT scanning. FLRT3, FGF2, and BMP2 expression was detected by immunofluorescence staining.

RESULTS

Under SMF stimulation, the cartilage of young rats grew longitudinally and laterally, and the thickness of the cartilage became thinner as it grew. The SMF promoted the proliferation and differentiation of condylar chondrocytes and endochondral ossification and increased subchondral bone mineral density, and BMP2 signaling was involved. Moreover, under SMF loading, the increased expression of FGF2 and FLRT3 were involved in regulating cartilage morphogenesis and growth. In late development, the decreased expression of FGF2/FLRT3 and the increased expression of BMP2 promoted endochondral ossification. The SMF accelerated this opposite expression trend.

CONCLUSION

FGF2/FLRT3 and BMP2 signals are involved in the regulatory effect of SMF exposure on chondrogenesis and endochondral ossification, which provides a theoretical basis for the clinical use of magnetic appliances to promote condylar growth.

Comparison of the treatment duration and effects of magnetic mandibular repositioning appliances and non-magnetic twin block in the treatment of growing patients with skeletal Class II malocclusion due to mandibular retrognathism – A systematic review

Over the past two decades, magnets have been used in orthodontics and dentofacial orthopedics and various attempts have been made to evaluate the biological implications of magnets and magnetic fields. This systematic review aims to provide a detailed comparison between magnetic mandibular repositioning appliances and non-magnetic twin blocks on mandibular growth modification. The objective was to evaluate the treatment duration and effects of magnetic mandibular repositioning appliances and non-magnetic twin block in growing children with skeletal Class II malocclusion due to mandibular retrognathism. Literature search of electronic databases and additional manual search was done till June 2021. Randomized controlled clinical trials (CCTs), non-randomized CCTs, case reports, case series, and retrospective clinical trials in which magnetic appliances and non-magnetic twin blocks were used for the correction of skeletal Class II malocclusion are included in the present review. Correction of skeletal Class II malocclusion was achieved in a shorter treatment duration with magnetic mandibular repositioning appliances. Similar dental and skeletal effects were observed with both the appliances; however, maxillary restraining effect and reduced mandibular incisor proclination was evident with magnetic mandibular repositioning appliances. Magnetic appliance is proven to be more effective in correction of skeletal Class II malocclusion with mandibular retrognathism and maxillary prognathism with proclined lower incisors. This systematic review was registered on Prospero with registration number CRD42020165297.

Skeletal and dental outcomes of a new magnetic functional appliance, the Sydney Magnoglide, in Class II correction

INTRODUCTION

The purpose of this prospective study was to evaluate the dentoskeletal effects of a new magnetic functional appliance, the Sydney Magnoglide (Macono Orthodontic Lab, Sydney, Australia), after both active treatment with the appliance and comprehensive fixed appliance therapy, compared with a group of untreated Class II controls.

METHODS

Thirty-four consecutively treated Class II Division 1 patients treated with the Sydney Magnoglide followed by fixed appliances were compared with 30 untreated Class II controls with the same initial dentoskeletal Class II features and matched for age and sex. Lateral cephalograms were taken before treatment, immediately after functional appliance therapy, and after comprehensive fixed appliance therapy. Cephalometric analyses included the Pancherz analysis and linear and angular measurements. The comparisons were made with Student t tests (P <0.05). There were 3 dropouts, for a final sample for statistical analysis of 31 subjects.

RESULTS

There was no statistically significant difference between the treated and control groups before treatment. Treatment with the Sydney Magnoglide and comprehensive fixed appliance therapy normalized the overjet and corrected the Class II relationship in all treated subjects. The ANB angle showed a reduction of 1.0°, as opposed to an increase of 0.3° in the untreated controls, and was associated with a statically significant improvement in the SNB angle (P <0.05). There was a significant gain of 2.3 mm in mandibular length in the treated group compared with the control group (P <0.01).

CONCLUSIONS

The outcomes of this prospective study demonstrate that the compliance-free Sydney Magnoglide is an effective functional appliance for Class II correction.

Post-treatment evaluation of a magnetic activator device in Class II high-angle malocclusions

SUMMARY

The purpose of this study was to evaluate changes in dentofacial growth before, during, and after use of a magnetic activator device (MAD) II in high-angle Class II division 1 patients. Lateral cephalometric and hand-wrist radiographs of 10 patients (six girls and four boys) with an average chronological age of 10 years 5 months were obtained at the beginning of the observation period (T1, 9.5 months), beginning of MAD II application (T2), at the end of the treatment (T3), and approximately 4 years after the end of treatment (T4). Thirteen linear, 1 ratio, and 10 angular measurements were evaluated. Paired t-tests were used for statistical evaluation of differences that occurred between the time points. The increase in gonial angle, GnGoAr angle, S-N, Co-Gn, Go-Ar, ANS-Me, S-Go, and N-Me distances and the decrease of overjet, U1-NA distance, and ANB angle were statistically significant during the treatment. At T4, there was a decrease in gonial angle and U1-NA distance, which was significant. The changes as a result of treatment were stable at T4.