Post-traumatic TMJ internal derangement: impact on facial growth (findings in a pediatric age group)

When trauma bites back: a systematic review on direct orofacial macrotrauma and temporomandibular disorders

OBJECTIVES

Temporomandibular disorders (TMD) are musculoskeletal conditions with a multifactorial aetiology. The predictive role of direct orofacial macrotrauma in the development of TMD is considered controversial. This systematic review aims to elucidate the association between direct orofacial macrotrauma and TMD, and to identify potential factors involved in this relationship.

MATERIALS AND METHODS

A comprehensive literature search of PubMed, Embase, and Web of Science databases up to November 1, 2023, was performed in collaboration with a medical information specialist, identifying 2,047 unique studies. Of these, 139 met the inclusion criteria of this investigation.

RESULTS

Our synthesis of the literature indicates a consistent association between TMD and direct orofacial macrotrauma in adults, while this relationship appears less defined in paediatric and adolescent populations. The association shows robustness across various TMD diagnoses and trauma locations, remaining not only immediately following the direct orofacial macrotrauma but also after long time, despite other interventions. These outcomes could be due to the physical effect of the trauma, but they might be associated with the psychosocial effect of the trauma as well.

CONCLUSIONS

The evidence supports a robust, but complex, association between direct orofacial macrotrauma and TMD.

CLINICAL RELEVANCE

This finding underscores the importance of considering both physical and psychosocial sequelae of trauma in the clinical management of direct orofacial macrotrauma and TMD.

Diagnosing temporomandibular joint disorders using second harmonic imaging of collagen fibers

This proposed optical imaging method is a nondestructive, real-time and high-resolution approach to distinguish healthy and injured temporomandibular joint (TMJ) tissues. And the TMJ health index was invented. TMJ pathologies are commonly and reported frequently. It could be associated with the damage of collagen, cartilage and bone tissue. The second harmonic generation images could be obtained by a femtosecond laser pulses, so the aligned information of the collagen fibers in all directions for the TMJ disorders was collected. The disorder degree of collagen fibers was quantified and ranked using a fast Fourier transform (FFT) method. The TMJ health index can effectively present the TMJ healthy condition and the disorder degree of collagen fibers, a valuable objective tool for tissue characterization for TMJ healthy condition. Integrated with the staining methods, we can provide the scaling information at different injury degree.

The Temporomandibular Joint: A Critical Review of Life-Support Functions, Development, Articular Surfaces, Biomechanics and Degeneration

The temporomandibular joint is a highly conserved articulation because it promotes survival and propagation via the essential functions of mastication, communication, and routine mating success (dentofacial esthetics). The temporomandibular joint is a unique secondary joint formed between the endochondral temporal bone and the mandibular secondary condylar cartilage via Indian hedgehog and bone morphogenetic protein signaling that is closely related to ear development. A dynamic epigenetic environment is provided by Spry1 and Spry2 genetic induction of the lateral pterygoid and temporalis muscles. Mechanical loading of the condylar periosteum during fetal development produces a superficial layer of fibrocartilage that separates from the condyle to form the interposed temporomandibular joint disc. The articular surfaces of the condyle and fossa are dynamically modified periosteum that has healing and regenerative capability. This unique tissue is composed of a superficial fibrous layer (synovial surface) with an underlying proliferative (cambium) layer that produces a cushioning layer of fibrocartilage which subsequently forms bone. Prior to occlusion of the first primary (deciduous) molars at about 16 months, facial development is dominated by primary genetic mechanisms. After achieving posterior functional occlusion, biomechanics enhances temporomandibular joint maturation, and assumes control of facial growth, development and adaptation. Concurrently, hypothalamus control of musculoskeletal physiology shifts from insulin-like growth factor IGF2 to IGF1, which affects bone via muscular loading (biomechanics). Three layers of temporomandibular joint fibrocartilage are resistant to heavy functional loading, but parafunctional clenching may result in degeneration that is first manifest as trabecular sclerosis of the mandibular condyle.