Uncovering the unique characteristics of the mandible to improve clinical approaches to mandibular regeneration

Prognostic implications of a CD8+ TEMRA to CD4+Treg imbalance in mandibular fracture healing: a prospective analysis of immune profiles

Introduction

Open reduction and fixation are the standard of care for treating mandibular fractures and usually lead to successful healing. However, complications such as delayed healing, non-union, and infection can compromise patient outcomes and increase healthcare costs. The initial inflammatory response, particularly the response involving specific CD8+ T cell subpopulations, is thought to play a critical role in healing long bone fractures. In this study, we investigated the role of these immune cell profiles in patients with impaired healing of mandibular fractures.

Materials and methods

In this prospective study, we included patients with mandibular fractures surgically treated at Charité - Universitätsmedizin Berlin, Germany, between September 2020 and December 2022. We used follow-up imaging and clinical assessment to evaluate bone healing. In addition, we analyzed immune cell profiles using flow cytometry and quantified cytokine levels using electrochemiluminescence-based multiplex immunoassays in preoperative blood samples.

Results

Out of the 55 patients enrolled, 38 met the inclusion criteria (30 men and 8 women; mean age 32.18 years). Radiographic evaluation revealed 31 cases of normal healing and 7 cases of incomplete consolidation, including 1 case of non-union. Patients with impaired healing exhibited increased levels of terminally differentiated effector memory CD8+ T cells (TEMRA) and a higher TEMRA to regulatory T cell (Treg) ratio, compared with those with normal healing.

Conclusions

Our analysis of mandibular fracture cases confirms our initial hypothesis derived from long bone fracture healing: monitoring the TEMRA to Treg ratio in preoperative blood can be an early indicator of patients at risk of impaired bone healing. Radiologic follow-up enabled us to detect healing complications that might not be detected by clinical assessment only. This study highlights the potential of individual immune profiles to predict successful healing and may form the basis for future strategies to manage healing complications.

Exploring the applications of platelet-rich plasma in tissue engineering and regenerative medicine: evidence from goat and sheep experimental research

Platelet-rich plasma (PRP) has emerged as a promising therapeutic approach in regenerative medicine. It contains various growth factors and bioactive molecules that play pivotal roles in tissue repair, regeneration, and inflammation modulation. This comprehensive narrative review delves into the therapeutic potential of PRP in experimental goat and sheep research, exploring recent advancements, challenges, and future prospects in the field. PRP has been explored for its application in musculoskeletal injuries, wound healing, and orthopedic conditions. Studies have demonstrated the ability of PRP to accelerate tissue healing, reduce inflammation, and improve the overall quality of healing. Recent advancements in PRP technology have led to the development of novel formulations and delivery methods to enhance its therapeutic efficacy. PRP has shown promise in tendon and ligament injuries, osteoarthritis, and bone fractures in experimental goat and sheep research. Despite these advancements, several challenges and opportunities exist to harness the full therapeutic potential of PRP in regenerative medicine. Standardizing PRP preparation protocols, including blood collection techniques, centrifugation parameters, and activation methods, is essential to ensure consistency and reproducibility of the findings. Moreover, further research is needed to elucidate the optimal dosing, frequency, and timing of PRP administration for different clinical indications. Research conducted in goat and sheep models provides evidence supporting the translational potential of PRP in tissue engineering and regenerative medicine. By harnessing the regenerative properties of PRP and leveraging insights from preclinical studies, researchers can develop innovative therapeutic strategies to address unmet clinical needs and improve patient outcomes in diverse medical specialties.

Biomechanical Evaluation of the Osseointegration Levels of Implants Placed Simultaneously With Tibia, Femur, and Jaw Allogeneic Bone Grafts

In implant-supported prosthetic treatments, the jaw bones may not always have enough bone to accommodate implants. Allogeneic grafts can also be preferred as an alternative to autogenous grafts in cases of vertical and horizontal bone deficiencies. The aim of this study is to evaluate the osseointegration levels of lathe-faced titanium implants placed together with allogeneic bone tissue transplants obtained from tibia, femur, and mandible bones using a biomechanical method. Twenty-eight female Sprague Dawley rats were included in the study. The subjects were divided into groups where bone transplantations were performed together with implant placement from the tibia (n=7), femur (n=7), and lower jaw (n=7) regions. Four rats (left and right) were used as donors. Grafts, along with implants, were surgically placed in the corticocancellous part of the metaphyseal parts of the tibia bones of rats. At the end of the 2-week experimental setup, all rats were killed, and the implants and surrounding bone tissues were subjected to biomechanical reverse torque analysis (N/cm), no statistical difference was detected in terms of bone-implant fusion between the groups in which the femur and tibia bones were transplanted (P>0.05), while the bone-implant fusion value in the group in which the lower jaw bone was transplanted was found to be statistically higher than the femur and tibia bones (P<0.05). Based on the limited results of this study, it can be thought that the lower jaw allogeneic jawbone has a higher osseointegration potential than allogeneic grafts obtained from the femur and tibia.

Thoughts on the Etiology of Cherubism

Cherubism is nowadays classified as an autoimmune disease and was first described in 1933. Although suspected at that time to be the result of defective tooth development, it was primarily classified as a bone disease caused by a mutation in the SH3BP2 gene. Despite a knock-in mouse model, phenotypic signs in the jaw area were not reproducible in this model. The features of classical cherubism can be attributed to a disturbed formation of the dental placode of the second molar. Since 2019, it has become clear that inhibition of the WNT pathway leads to the accumulation of SH3BP2 via tankyrase inhibition. As the dental placode is triggered via WNT (in epithelia) and MSX1 (in mesenchyme), aplasia of the second and third molars occurs due to a block in the WNT pathway. The mesenchymal part, which occurs prior to the body plan regulation of the WNT/MSX1 pathway, remains unaffected and provides the substrate for the giant cell granuloma. Considering macrophage polarization and the role of the extracellular matrix in general, cherubism is situated in the field of tension between autoimmune diseases and cancer. In this sense, we see the cause of cherubism in a WNT-related dysregulation, which can be proven postnatally in the neural crest-related tooth development of the replacement tooth ridge, both genotypically and phenotypically.

Features and networks of the mandible on computed tomography

The mandible or lower jaw is the largest and hardest bone in the human facial skeleton. Fractures of the mandible are reported to be a common facial trauma in emergency medicine and gaining insights into mandibular morphology in different facial types can be helpful for trauma treatment. Furthermore, features of the mandible play an important role in forensics and anthropology for identifying gender and individuals. Thus, discovering hidden information of the mandible can benefit interdisciplinary research. Here, for the first time, a method of artificial intelligence-based nonlinear dynamics and network analysis are used for discovering dissimilar and similar radiographic features of mandibles between male and female subjects. Using a public dataset of 10 computed tomography scans of mandibles, the results suggest a difference in the distribution of spatial autocorrelation between genders, uniqueness in network topologies among individuals and shared values in recurrence quantification.