The Management of Patients after Surgical Treatment of Maxillofacial Tumors

Prosthetic rehabilitation of patients with maxillary oncology defects using zygomatic implants

PURPOSE

Prosthetics for patients after oncological resection of the upper jaw is a complex problem associated with the physiological and anatomical separation of the oral cavity and the nasal/paranasal region. This study reports the clinical results of the use of the zygomatic implants for prosthetic rehabilitation in patients with maxillectomy due to upper jaw tumors.

MATERIALS AND METHODS

The study included 16 patients who underwent prosthetic rehabilitation using a zygomatic implant after maxillectomy period from 2021 to 2023. After the tumor was removed, immediate surgical obturators were placed. Main prosthetic rehabilitation was performed 6-12 months after tumor removal, but before that, a temporary obturator was made and used. Six-twelve months after tumor resection, 1-4 zygomatic implants were inserted into the zygomatic bone unilaterally or bilaterally. A total of 42 zygomatic implants were installed, 2 of which were unsuccessful and were removed in 1 patient. The implants were placed using the surgical guide, which was planned and prepared digitally.

RESULTS

No postsurgical complications were seen, and the patients were discharged from the hospital after 7-10 days. The patients were able to return to a normal diet (hard food) after just 7 days following surgery, with no further complaints regarding function or pain, apart from the residual edema caused by the intervention.

CONCLUSIONS

The use of prostheses fixed on zygomatic implants in patients with maxillary defects is an effective method of prosthodontic rehabilitation in complex clinical cases after maxillectomy.

Diagnostic and Prognostic Value of Indicators of Bone Metabolism Markers in Patients Following Mandibulectomy and Free Fibula Flap Reconstruction with Endosteal Implants

Purpose

To evaluate and assess the indicators of bone metabolism markers osteocalcin and β-Cross-Laps in blood serum as a tool for monitoring bone regeneration and determining the time of implantation in patients after mandibulectomy and reconstruction of a free fibular flap with subsequent endosteal implants.

Materials and Methods

Forty-eight patients in a 6-year period participated in this study, due to resection for tumors. All patients underwent reconstruction with fibula free flap after tumor resection, 4-6 months after osteoectomy, dental implants were installed with further orthopedic rehabilitation. To assess the rate of bone remodeling after transplantation, the content biochemical markers of bone remodeling osteocalcin and β-Cross-Laps serum were determined by enzyme immunoassay.

Results

All 46 fibular free flaps were healed without complications and were survived. A total 326 implants installed, 8 implants failed to osseointegrate, and 6 implants failed after 5 years of loading (peri-implantitis). Success rate of implants after 5 years was 95,7%. In patients before surgery, the mean of osteocalcin levels was 8.5 ng/ml, two months later, there was a sharp increase in the content of osteocalcin by 15.4 ng/ml, after four months reached 24.7 ng/ml, after six months of 28.6 ng/ml, then the indicator began to decrease and after 12 months it was approaching the norm of 14.7 ng/ml. In patients before surgery, the mean level of β-Cross-Laps was 0.76 ng/ml, after two months bone transplantation the mean level of β-Cross-Laps decreased to - 0.65 ng/ml, after four months the indicator increased and reached of 0.98 ng/ml, after six months the indicator was - 1.56 ng/ml, then these indicators began to decrease and after 12 months, approaching normal values of - 0.87 ng/ml. There is a correlation between different concentrations of osteocalcin or β-Cross- Laps and the success rate of implants. Implants were shown to be unsuccessful low concentrations of osteocalcin and high concentrations of β-Cross-Laps in serum.

Conclusion

Studies have shown that the long-term survival and success rates of implants placed in the reconstructed areas may guarantee an excellent prognosis of implant-supported prostheses. Bone markers in blood serum osteocalcin and β-Cross-Laps can be used to evaluate the rate of bone remodeling, which allows you to determine the time of implantation.

Effectiveness of dental implants in patients undergoing radiotherapy for head and neck cancer: An umbrella review

OBJECTIVE

The objective of this overview is to evaluate the effectiveness of dental implants placed in patients who underwent radiotherapy for the treatment of head and neck cancer, as well as to assess the methodological quality of the included systematic reviews.

METHODS

The study was conducted in four PubMed, Lilacs, Dare Cochrane and Google Scholar databases until July 2022, using the descriptors "Radiotherapy," "Dental implants," and "Head and Neck Cancer."

RESULTS

958 studies were found in the initial search and after applying the inclusion and exclusion criteria, fifteen systematic reviews were selected to compose this overview and had their methodological quality evaluated by the AMSTAR 2 tool.

RESULTS

24,996 implants in 5487 patients were evaluated with a rate of success rate of 86.2% in patients who underwent radiotherapy and 95.2% in patients who did not undergo radiotherapy. Only one of the systematic reviews was of high quality according to AMSTAR 2.

CONCLUSION

Oral rehabilitation with dental implants in patients with a history of head and neck cancer undergoing radiotherapy is a valid therapy. However, given the level of evidence found, further studies with better design are necessary to provide greater confidence in the clinical decision.

[Dental rehabilitation in the complex treatment of children and adolescents with maxillofacial neoplasms]

THE PURPOSE

Of the study was to improve algorithms and methods of complex dental rehabilitation of children and adolescents with maxillofacial neoplasms.

MATERIALS AND METHODS

Sixty-seven patients aged from 2 to 17 years (average age 10.43±4.56; 30 boys, 37 girls) underwent complex rehabilitation as a part of neoplasm treatment (40 benign, 27 malignant). Patients were divided into 3 groups: group 1 aged 2 to 7 years; group 2 aged 8 to 12 years; group 3 aged 13 to 17 years.

RESULTS

Structural integrity of upper and lower jaws was reconstructed using vascularized bone flaps (27 cases), non-vascularized bone flaps (5 cases), titanium reconstructive plates (11 cases) or individual titanium endoprostheses of the temporomandibular joint (2 cases). Orthodontic, orthopedic and surgical dental treatment was performed at all stages of rehabilitation of patients and had its own characteristics depending on the group affiliation.

CONCLUSION

Algorithms for dental rehabilitation of children and adolescents with maxillofacial neoplasms have been improved on the base of performed treatment.

MMP-1 promotes osteogenic differentiation of human bone marrow mesenchymal stem cells via the JNK and ERK pathway

Enhancing the functions of mesenchymal stem cells (MSCs) is considered a potential approach for promoting tissue regeneration. In this study, we investigated the effects of Matrix Metalloproteinase-1 (MMP-1) on bone marrow mesenchymal stem cells (BMSCs) and its mechanism. Our results showed that knockdown of MMP-1 impeded scratch closure, attenuated proliferation, inhibited ALP activity, ALP denser staining and mineralization in vitro, and decreased expression of RUNX2, OSX, OPN and OCN in BMSCs, while 20 ng/mL recombinant human MMP-1 protein (rhMMP-1) significantly accelerated scratch closure, enhanced proliferation, ALP activity, ALP denser staining and mineralization in vitro, and increased expression of RUNX2, OSX, OPN and OCN. In addition, knockdown of MMP-1 inhibited the expression of phosphorylated c-Jun N-terminal kinase (p-JNK) and phosphorylated extracellular regulated protein kinases (p-ERK), while 20 ng/mL rhMMP-1 increased the expression of p-JNK and p-ERK in BMSCs. Furthermore, inhibition of c-Jun N-terminal kinase (JNK) and extracellular regulated protein kinases (ERK) by their inhibitor SP600125 and PD98059 dramatically blocked MMP-1-enhanced ALP activity and mineralization in BMSCs. Our results revealed that MMP-1 could accelerate the osteogenic differentiation potentials of BMSCs via the JNK and ERK pathway, providing the mechanism underlying MSC biology and identifying a potential target for improving bone tissue regeneration.

BMP9 is a potential therapeutic agent for use in oral and maxillofacial bone tissue engineering

Oral and maxillofacial surgery is often challenging due to defective bone healing owing to the microbial environment of the oral cavity, the additional involvement of teeth and esthetic concerns. Insufficient bone volume as a consequence of aging and some oral and maxillofacial surgical procedures, such as tumor resection of the jaw, may further impact facial esthetics and cause the failure of certain procedures, such as oral and maxillofacial implantation. Bone morphogenetic protein (BMP) 9 (BMP9) is one of the most effective BMPs to induce the osteogenic differentiation of different stem cells. A large cross-talk network that includes the BMP9, Wnt/β, Hedgehog, EGF, TGF-β and Notch signaling pathways finely regulates osteogenesis induced by BMP9. Epigenetic control during BMP9-induced osteogenesis is mainly dependent on histone deacetylases (HDACs), microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), which adds another layer of complexity. As a result, all these factors work together to orchestrate the molecular and cellular events underlying BMP9-related tissue engineering. In this review, we summarize our current understanding of the SMAD-dependent and SMAD-independent BMP9 pathways, with a particular focus on cross-talk and cross-regulation between BMP9 and other major signaling pathways in BMP9-induced osteogenesis. Furthermore, recently discovered epigenetic regulation of BMP9 pathways and the molecular and cellular basis of the application of BMP9 in tissue engineering in current oral and maxillofacial surgery and other orthopedic-related clinical settings are also discussed.

Effect of Radiation on DCE-MRI Pharmacokinetic Parameters in a Rabbit Model of Compromised Maxillofacial Wound Healing: A Pilot Study

PURPOSE

Osteoradionecrosis (ORN), a potentially debilitating complication of maxillofacial radiation, continues to present a challenging clinical scenario, with limited treatment options that often fail. Translational animal models that can accurately mimic the human characteristics of the condition are lacking. In the present pilot study, we aimed to characterize the effects of radiation on the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) pharmacokinetic parameters in a rabbit model of compromised maxillofacial wound healing to determine its potential as a translational model of ORN.

MATERIALS AND METHODS

An experimental group underwent fractionated radiation of the mandible totaling 36 Gy. At 4 weeks after irradiation, the experimental and control groups (n = 8 rabbits each) underwent a surgical procedure to create a critical size defect in the mandibular bone. DCE-MRI scans were acquired 1 week after arrival (baseline; time point 1), 4 weeks after completion of irradiation in the experimental group (just before surgery, time point 2), and 4 weeks after surgery (time point 3).

RESULTS

No differences in the analyzed DCE-MRI parameters were noted within the experimental or control group between the baseline values (time point 1) and those after irradiation (time point 2). The whole blood volume fraction (v_b) in the experimental group was increased compared with that in the control group after irradiation (time point 2; P < .05). After surgery (time point 3), both the forward flux rate of contrast from blood plasma and the extracellular extravascular space and the v_b were increased in the control group compared with the experimental group (P < .05).

CONCLUSIONS

The results of the present study suggest that DCE-MRI of a rabbit model of compromised maxillofacial wound healing could reflect the DCE-MRI characteristics of human patients with ORN and those at risk of developing the condition. Future studies will focus on further characterization of this rabbit model as a translational preclinical model of ORN.

Bone Tissue Regeneration in the Oral and Maxillofacial Region: A Review on the Application of Stem Cells and New Strategies to Improve Vascularization

Bone tissue engineering techniques are a promising alternative for the use of autologous bone grafts to reconstruct bone defects in the oral and maxillofacial region. However, for successful bone regeneration, adequate vascularization is a prerequisite. This review presents and discusses the application of stem cells and new strategies to improve vascularization, which may lead to feasible clinical applications. Multiple sources of stem cells have been investigated for bone tissue engineering. The stromal vascular fraction (SVF) of human adipose tissue is considered a promising single source for a heterogeneous population of essential cells with, amongst others, osteogenic and angiogenic potential. Enhanced vascularization of tissue-engineered grafts can be achieved by different mechanisms: vascular ingrowth directed from the surrounding host tissue to the implanted graft, vice versa, or concomitantly. Vascular ingrowth into the implanted graft can be enhanced by (i) optimizing the material properties of scaffolds and (ii) their bioactivation by incorporation of growth factors or cell seeding. Vascular ingrowth directed from the implanted graft towards the host tissue can be achieved by incorporating the graft with either (i) preformed microvascular networks or (ii) microvascular fragments (MF). The latter may have stimulating actions on both vascular ingrowth and outgrowth, since they contain angiogenic stem cells like SVF, as well as vascularized matrix fragments. Both adipose tissue-derived SVF and MF are cell sources with clinical feasibility due to their large quantities that can be harvested and applied in a one-step surgical procedure. During the past years, important advancements of stem cell application and vascularization in bone tissue regeneration have been made. The development of engineered in vitro 3D models mimicking the bone defect environment would facilitate new strategies in bone tissue engineering. Successful clinical application requires innovative future investigations enhancing vascularization.

Examination of Oral Microbiota Diversity in Adults and Older Adults as an Approach to Prevent Spread of Risk Factors for Human Infections

The oral cavity environment may be colonized by polymicrobial communities with complex, poorly known interrelations. The aim of this study was to determine oral microbiota diversity in order to prevent the spread of infectious microorganisms that are risk factors for human health complications in patients requiring treatment due to various disabilities. The study examined Polish adults aged between 40 and 70 years; parasitological, microbiological, and mycological data collected before treatment were analyzed. The diversity of oral microbiota, including relatively high prevalences of some opportunistic, potentially pathogenic strains of bacteria, protozoans, and fungi detected in the patients analyzed, may result in increasing risk of disseminated infections from the oral cavity to neighboring structures and other organs. Increasing ageing of human populations is noted in recent decades in many countries, including Poland. The growing number of older adults with different oral health disabilities, who are more prone to development of oral and systemic pathology, is an increasing medical problem. Results of this retrospective study showed the urgent need to pay more attention to the pretreatment examination of components of the oral microbiome, especially to the strains, which are etiological agents of human opportunistic infections and are particularly dangerous for older adults.

Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels.