BACKGROUND: Over the past decade, orthodontics has advanced markedly with digital methods, cutting-edge biomechanics, and 3-dimensional diagnostics. However, the rapid adoption of these innovations without rigorous evaluation of their evidential support has led to new unsubstantiated orthodontic-surgical indications.
METHODS: This article explores emerging orthodontic practices, focusing on the interpretation of orthodontic principles and the reliance on imaging-based diagnoses.
RESULTS: Strict adherence to mechanistic orthodontic principles and reliance on imaging findings can result in overzealous treatment protocols. It also emphasizes the state of knowledge regarding temporomandibular disorders (TMDs) and the lack of consensus and evidence-based guidelines.
CONCLUSIONS: There is an urgent need for the profession to integrate TMD knowledge, adopt evidence-based practices, and critically evaluate new methods before implementation.
CONCLUSIONS: Orthodontists should move away from outdated mechanistic beliefs and integrate clinical knowledge from TMD research into their practices. Increased awareness and potential legal repercussions may drive a necessary reevaluation and stronger adherence to evidence-based methods.

BACKGROUND: Pathological alterations of lateral pterygoid muscle (LPM) are implicated in temporomandibular joint anterior disk displacement (ADD). However, quantification of the fatty infiltration of LPM and its correlation with ADD have rarely been reported. The aim of this study was to evaluate the fatty infiltration, morphological features and texture features of LPM in patients with ADD using T1-weighted Dixon sequence.
METHODS: This retrospective study included patients who underwent temporomandibular joint MRI with T1-weighted Dixon sequence between December 2018 and August 2020. The temporomandibular joints of the included patients were divided into three groups according to the position of disk: Normal position disk (NP) group, Anterior disk displacement with reduction (ADDWR) group and Anterior disk displacement without reduction (ADDWOR) group. Fat fraction, morphological features (Length; Width; Thickness), and texture features (Angular second moment; Contrast; Correlation; Inverse different moment; Entropy) extracted from in-phase image of LPM were evaluated. One-way ANOVA, Welch\'s ANOVA, Kruskal-Wallis test, Spearman and Pearson correlation analysis were performed. Intra-class correlation coefficient was used to evaluate the reproducibility.
RESULTS: A total of 53 patients with 106 temporomandibular joints were evaluated. Anterior disk displacement without reduction group showed higher fat fraction than normal position disk group (P = 0.024). Length of LPM was negatively correlated with fat fraction (r = -0.22, P = 0.026). Angular second moment (ρ = -0.32, P < 0.001), correlation (ρ = -0.28, P = 0.003) and inverse different moment (ρ = -0.27, P = 0.005) were negatively correlated with fat fraction, while positive correlation was found between entropy and fat fraction (ρ = 0.31, P = 0.001). The intra-class correlation coefficients for all values were ranged from 0.80 to 0.97.
CONCLUSIONS: Patients with ADDWOR present more fatty infiltration in the LPM compared to NP or ADDWR patients. Fatty infiltration of LPM was associated with more atrophic and higher intramuscular heterogeneity in patients with ADD. Fat fraction of LPM quantitatively and noninvasively evaluated by Dixon sequence may has utility as an imaging-based marker of the structural severity of ADD disease process, which could be clinical helpful for the early diagnose of ADD and predication of disease progression.

OBJECTIVE: Anterior disk displacement (ADD) is a most common subtype of temporomandibular disorders (TMD), which is promoted by chondrocytes apoptosis. However, the signaling pathways that trigger apoptosis are still unknown. The aim of this study was to investigate the expression of endoplasmic reticulum (ER) stress-related proteins in the condylar cartilage of rabbits following ADD.
METHODS: Sixty healthy adult rabbits were randomly assigned to the experimental and sham-operated control groups (n = 12). The experimental rabbits were subjected to surgical ADD in the right temporomandibular joints. The production of ER stress-related proteins C/EBP homologous protein (CHOP), glucose-regulated protein 78 (GRP78), cleaved caspase-3, and caspase-12 in cartilage was evaluated by immunohistochemistry, quantitative real-time PCR, and Western blot analysis.
RESULTS: Our results showed that the expression of CHOP, GRP78, cleaved caspase-3, and caspase-12 increased significantly along with degenerative changes in cartilage after ADD.
CONCLUSIONS: These results indicate that the ER stress pathway is activated in ADD cartilage and might promote the development of TMD.