Photobiomodulation and Mandibular Advancement Modulates Cartilage Thickness and Matrix Deposition in the Mandibular Condyle

Influence on the temporomandibular joint induced by mandibular malpositioning caused by vertical dimension elevation and occlusal loss in adult rats: An imaging, histological and immunohistochemical study

BACKGROUND

Mandibular malpositioning may result in an abnormal concentration of stresses within the temporomandibular joint (TMJ) in adult rats, which may further lead to a series of pathological changes, such as articular cartilage wear, subchondral bone sclerosis and osteophyte formation. However, the pathological and adaptive changes in condylar cartilage caused by different stress distributions are still controversial.

OBJECTIVE

The aim of this study was to observe the effect of sagittal changes in mandibular position on condylar cartilage by changing the occlusal vertical dimension (OVD) in adult rats.

METHODS

Fifteen-week-old female rats were divided into three groups: control (CON), increased OVD (iOVD) and loss of occlusion (LO) groups. An occlusal plate and tooth extraction were used to establish the animal model. TMJ samples of the experimental and CON groups were observed and investigated by bone morphological, histomorphological and immunohistochemical staining analyses at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks. Weight curves were plotted.

RESULTS

Micro-computed tomography showed that, compared with the CON group, cartilage destruction followed by repair occurred in both experimental groups, which was similar to the trend observed in haematoxylin-eosin staining. All experimental results for the iOVD group showed an approximately similar time trend. Compared with the iOVD group, the toluidine blue and immunohistochemical staining results in the LO group showed no obvious change trend over time.

CONCLUSION

Compared with occlusal loss, an increase in OVD caused faster and more severe damage to condylar cartilage, and subchondral bone repair occurred later.

Fabrication of novel nanofiber composed of gelatin/alginate with zirconium oxide NPs regulate orthodontic progression of cartilage degeneration on Wnt/β-catenin signaling axis in MC3T3-E1 cells

Natural macromolecules like alginate and gelatin are employed to create medication delivery systems that are both safe and effective. Zirconium nanoparticles (ZrO2 NPs) have been proposed as a means of enhancing the alginate-gelatin hydrogel's physical and biological properties. This study combines the synthesis of the biopolymers gelatin and alginate nanofibers with nanoparticles of zirconium oxide (GA/NF- ZrO2 NPs). UV, XRD, FTIR, and SEM were used to characterize the synthesized nanofibers. The expression of osteogenic genes was analyzed by western blotting and qualitative real-time polymerase chain reaction (qRT-PCR). Based on our findings, MC3T3-E1 cells are performed for cell viability, apoptosis and reactive oxygen species production by GA/NF- ZrO2 NPs through the Wnt/β-catenin signaling pathway. Cell migration was accelerated at 75 μg/mL concentration after 24 h of damage in a scratch wound healing assay. Proliferation of the MC3T3-E1 cell line was also detected. GA/NF-ZrO2 NPs influenced the osteogenic variation of MC3T3-E1 cells by inducing autophagy. Furthermore, the impact of obstruction on the temporomandibular joint (TMJ) is a subject of ongoing discussion and analysis within the context of animal models. Coordinated GA/NF-ZrO2 NPs on biomaterial nanofibers could be used to introduce physical signals for modifying MC3T3-E1 responds for orthodontic engineering constructs.

Effect of low-level laser therapy on condylar growth in children treated with functional appliance: a preliminary study

Purpose

This study aimed to evaluate the skeletal and dentoalveolar changes achieved by combining low-level laser irradiation applied on the condyle area with twin-block therapy in growing class II malocclusion patients.

Methods

Fourteen patients (9 males, 5 females; mean age, 11.4 ± 2 years) with skeletal class II mandibular deficiency were recruited. They were divided into two groups (G 1: twin-block + low-level laser therapy, G 2: twin-block only). A semiconductor diode laser with a wavelength of 940 nm was applied on the condyle area (100 mW, 2.5 J, 3.9 J/cm²). The laser was applied twice a week in the first month and once a week in the second and third months, totalizing 16 sessions. Skeletal, dental, and soft-tissue cephalometric parameters were measured and compared at different treatment points.

Results

Mandibular length (Co-Gn) was significantly increased by 3.6 mm in the experiment group (3.16 SD) and 4.3 mm (4.4 SD) in the control group, with no significant difference between groups at every time point (P-value 0.949 at T2). Similarly, a statistically significant positive effect of treatment was found in both groups on ramus height (Co-Go), upper lip to E-Line, SNA angle, ANB angle, and U1/SN angle with no significant difference between groups.

Conclusion

Based on the results of this preliminary study, low-level laser irradiation with the used parameters seems to have no synergetic impact on the skeletal and dental outcomes of twin-block therapy over 9 months. However, more studies are needed to investigate the effect of low-level laser therapy on condylar growth during functional orthodontic treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41547-022-00158-x.