Virtual reconstruction of orbital defects using Gaussian process morphable models.

PURPOSE: The conventional method to reconstruct the bone level for orbital defects, which is based on mirroring and manual adaptation, is time-consuming and the accuracy highly depends on the expertise of the clinical engineer. The aim of this study is to propose and evaluate an automated reconstruction method utilizing a Gaussian process morphable model (GPMM). METHODS: Sixty-five Computed Tomography (CT) scans of healthy midfaces were used to create a GPMM that can model shape variations of the orbital region. Parameter optimization was performed by evaluating several quantitative metrics inspired on the shape modeling literature, e.g. generalization and specificity. The reconstruction error was estimated by reconstructing artificial defects created in orbits from fifteen CT scans that were not included in the GPMM. The developed algorithms utilize the existing framework of Gaussian process morphable models, as implemented in the Scalismo software. RESULTS: By evaluating the proposed quality metrics, adequate parameters are chosen for non-rigid registration and reconstruction. The resulting median reconstruction error using the GPMM was lower (0.35 ± 0.16 mm) compared to the mirroring method (0.52 ± 0.18 mm). In addition, the GPMM-based reconstruction is automated and can be applied to large bilateral defects with a median reconstruction error of 0.39 ± 0.11 mm. CONCLUSION: The GPMM-based reconstruction proves to be less time-consuming and more accurate than reconstruction by mirroring. Further validation through clinical studies on patients with orbital defects is warranted. Nevertheless, the results underscore the potential of GPMM-based reconstruction as a promising alternative for designing patient-specific implants.

Bridging the knowledge-Practice gap: Insights from a survey of Belgian dental professionals on diagnosis and supportive oral cancer treatment in comparison with international guidelines.

OBJECTIVE: Early detection significantly improves the prognosis of oral cancer patients, contingent upon the knowledge of dental professionals. This study aimed to assess and compare the knowledge, practices and perceptions regarding oral cancer among dental professionals in Belgium. MATERIALS AND METHODS: A cross-sectional survey was distributed via Qualtrics to general dentists, dental specialists, dental hygienists, and oral and maxillofacial surgeons. The self-administered questionnaire comprised three sections: demographics (4 questions), knowledge (9 questions) and clinical practices (19 questions) related to oral cancer detection and treatment. Descriptive statistics were employed for data analysis, with Chi-square tests assessing responses by specialization, gender, years of experience and number of oral cancer patients treated. RESULTS: A total of 262 questionnaires were completed, with the majority of respondents being general dentists (61%) followed by dental specialists (25%), oral hygienists (8%) and oral and maxillofacial surgeons (6%). 70% of the respondents reported treating fewer than four oral cancer patients throughout their careers. 5 out of the 9 knowledge questions achieved over 50% correct responses, with an average correct answer rate of 54%. Oral and maxillofacial surgeons and dental professionals who have treated more than four oral cancer patients, demonstrated significantly higher scores on multiple knowledge questions. Responses to clinically oriented questions showed less diversity across professions, and generally aligning with guidelines from professional oncological societies. CONCLUSION: This survey highlights the need for enhanced education on oral cancer among Belgian dental professionals. Knowledge levels were notably higher among more experienced respondents. The development and implementation of comprehensive guidelines tailored to dentists and oral hygienists for oral cancer prevention and patient care are warranted to optimize clinical practice standards.

CD4+ T cell activation distinguishes response to anti-PD-L1+anti-CTLA4 therapy from anti-PD-L1 monotherapy.

Cancer patients often receive a combination of antibodies targeting programmed death-ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen-4 (CTLA4). We conducted a window-of-opportunity study in head and neck squamous cell carcinoma (HNSCC) to examine the contribution of anti-CTLA4 to anti-PD-L1 therapy. Single-cell profiling of on- versus pre-treatment biopsies identified T cell expansion as an early response marker. In tumors, anti-PD-L1 triggered the expansion of mostly CD8+ T cells, whereas combination therapy expanded both CD4+ and CD8+ T cells. Such CD4+ T cells exhibited an activated T helper 1 (Th1) phenotype. CD4+ and CD8+ T cells co-localized with and were surrounded by dendritic cells expressing T cell homing factors or antibody-producing plasma cells. T cell receptor tracing suggests that anti-CTLA4, but not anti-PD-L1, triggers the trafficking of CD4+ naive/central-memory T cells from tumor-draining lymph nodes (tdLNs), via blood, to the tumor wherein T cells acquire a Th1 phenotype. Thus, CD4+ T cell activation and recruitment from tdLNs are hallmarks of early response to anti-PD-L1 plus anti-CTLA4 in HNSCC.

Exploring long-term responses to immune checkpoint inhibitors in recurrent and metastatic head and neck squamous cell carcinoma.

OBJECTIVES: Immune checkpoint inhibitors (ICI) have introduced a new era in the treatment of recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC). Optimal duration for ICI therapy is still unclear and the long-term outcomes and toxicity in patients responding to these therapies warrant further exploration. This study attempts to identify the clinical and biological determinants of a durable response and evaluate outcomes following ICI treatment discontinuation. MATERIALS AND METHODS: A retrospective review of 181 patients treated with ICI for R/M HNSCC was conducted. Long-term responders were defined as patients who sustained disease control at least two years after initiating ICI therapy. We compared clinical and biological characteristics associated with these long-term responders against the broader treatment population. RESULTS: 10 % of R/M HNSCC patients treated with ICIs demonstrated a durable long-term response. Only three relapses (16 %) occurred after discontinuing ICI treatment in this subset, with a median follow-up of 52 months. Upon retreatment with ICI, two attained a documented response. Extended ICI response was observed even with < 2 years of treatment. 74 % of long-term responders experienced immune-related adverse events (irAEs), 37 % of which severe irAEs. Hypothyroidism was the most frequently reported irAEs. The predictive potential of systemic inflammation indices for clinical response appears to be limited. CONCLUSIONS: ICI present an optimistic avenue for HNSCC patients, offering substantial long-term responses. The study suggests that a two-year treatment could be optimal and irAEs, although common, are typically mild.

Biomechanical feasibility of non-locking system in patient-specific mandibular reconstruction using fibular free flaps.

Mandibular reconstruction with free fibular flaps is frequently used to restore segmental defects. The osteosythesis, including locking and non-locking plate/screw systems, is essential to the mandibular reconstruction. Compared with the non-locking system that requires good adaption between plate and bone, the locking system appears to present a better performance by locking the plate to fixation screws. However, it also brings about limitations on screw options, a higher risk of screw failure, and difficulties in screw placement. Furthermore, its superiority is undermined by the advancing of patient-specific implant design and additive manufacturing. A customized plate can be designed and fabricated to accurately match the mandibular contour for patient-specific mandibular reconstruction. Consequently, the non-locking system seems more practicable with such personalized plates, and its biomechanical feasibility ought to be estimated. Finite element analyses of mandibular reconstruction assemblies were conducted for four most common segmental mandibular reconstructions regarding locking and non-locking systems under incisal biting and right molars clenching, during which the influencing factor of muscles' capacity was introduced to simulate the practical loadings after mandibular resection and reconstruction surgeries. Much higher, somewhat lower, and similar maximum von Mises stresses are separately manifested by the patient-specific mandibular reconstruction plate (PSMRP), fixation screws, and reconstructed mandible with the non-locking system than those with the locking system. Equivalent maximum displacements are identified between PSMRPs, fixation screws, and reconstructed mandibles with the non-locking and locking system in all four reconstruction types during two masticatory tasks. Parallel maximum and minimum principal strain distributions are shared by the reconstructed mandibles with the non-locking and locking system in four mandibular reconstructions during both occlusions. Conclusively, it is feasible to use the non-locking system in case of patient-specific mandibular reconstruction with fibular free flaps based on the adequate safety, comparable stability, and analogous mechanobiology it presents compared with the locking system in a more manufacturable and economical way.

The predictive and prognostic value of weight loss and body composition prior to and during immune checkpoint inhibition in recurrent or metastatic head and neck cancer patients.

BACKGROUND: Response rates of immune checkpoint inhibitor (ICI) therapy for recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) are low. PATIENTS AND METHODS: This retrospective multicentre cohort study evaluates the predictive and prognostic value of weight loss and changes in body composition prior and during therapy. Patient, tumor, and treatment characteristics of 98 patients were retrieved, including neutrophil and platelet-lymphocyte-ratio (NLR and PLR). Programmed death-ligand 1 (PD-L1) expression was determined on residual material. Cachexia was defined according to Fearon et al. (2011). Skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were evaluated on computed tomography scans at the third lumbar vertebrae level. Univariable and multivariable regression analyses were performed for 6 months progression free survival (PFS6m) and overall survival (OS). RESULTS: Significant early weight loss (>2%) during the first 6 weeks of therapy was shown in 34 patients (35%). This patient subgroup had a significantly higher NLR and PLR at baseline. NLR and PLR were inversely correlated with SM and VAT index. Independent predictors of PFS6m were lower World Health Organization performance status (HR 0.16 [0.04-0.54] p = 0.003), higher baseline SAT index (HR 1.045 [1.02-1.08] p = 0.003), and weight loss <2% (HR 0.85 [0.74-0.98] p = 0.03). Baseline cachexia in combination with >2% early weight loss remained a predictor of OS, independent of PD-L1 expression (HR 2.09 [1.11-3.92] p = 0.02, HR 2.18 [1.13-4.21] p = 0.02). CONCLUSION: We conclude that the combination of cachexia at baseline and weight loss during ICI therapy is associated with worse OS in R/M HNSCC patients, independent of PD-L1 expression.

High doses of zoledronic acid induce differential effects on femur and jawbone microstructure.

OBJECTIVES: The aim of this study is to investigate the long-term effects on jaw and femur bone induced by oncologic doses of zoledronic acid in a young rat model. MATERIAL AND METHODS: Six 12-week-old male Wistar rats received zoledronic acid (0.6 mg/kg) and six control rats received saline solution in the same volume. Compounds were administered intraperitoneally in five doses every 28 days. Euthanasia was performed 150 days after therapy onset. After animal sacrifice, their mandibles and femurs were scanned ex vivo using a high-resolution (14 µm) micro-computed tomography. Morphometric bone parameters were calculated using CT-Analyzer (Bruker, Belgium) between the first and second mandibular molars and in the distal femur metaphysis and epiphysis. RESULTS: The treatment group as compared to the controls showed a significantly (p < .05) increased bone quantity (↑BV/TV, ↓Po[Tot], ↑Tb.Th), bone density (↑TMD, ↑BMD), and osteosclerosis of the trabecular bone (↓Tb.Sp, ↓Conn.Dn, ↓Tb.Pf, ↓SMI) in all anatomical sites. Bone remodeling suppression due to zoledronic acid treatment was more pronounced (p < .05) in the femoral metaphysis relative to the mandible and epiphysis. The exploratory linear discriminant analysis showed that for the mandible, it was mainly the bone quantity-related morphometric indices (BV/TV and Tb.Th), while for the femoral epiphysis and metaphysis, it was bone structure-related (Tb.Pf and Tb.N), which are of primary importance to study the treatment effect. CONCLUSION: High doses of bisphosphonates can differently affect the bone quantity, density, and structure in long bones and jawbones. In the metaphysis, bone changes were primarily concentrated in the region of the growth plate. Future studies may consider the use of bone morphometric indices to evaluate the effect of bisphosphonates.

Biomechanical validation of structural optimized patient-specific mandibular reconstruction plate orienting additive manufacturing.

BACKGROUND AND OBJECTIVE: Owing to the unexpected in vivo fracture failure of the original design, structural optimized patient-specific mandibular reconstruction plates (PSMRPs) were created to boost the biomechanical performance of bridging segmental bony defect in the mandibular reconstruction after tumor resection. This work aimed to validate the biomechanical benefit of the structural optimized PSMRPs relative to the original design and compare the biomechanical performance between PSMRP1 with generic contour customization and PSMRP2 with a tangent arc upper margin in mandibular angle region. METHODS: Finite Element Analysis (FEA) was used to evaluate the biomechanical behavior of mandibular reconstruction assemblies (MRAs) concerning these two structural optimized PSMRPs by simulating momentary left group clenching and incisal clenching tasks. Bonded contact was set between mandibular bone and fixation screws and between PSMRP and fixation screws in the MRA, while the frictionless connection was allocated between mandibular bone and PSMRP. The loads were applied on four principal muscles, including masseter, temporalis, lateral and medial pterygoid, whose magnitudes along the three orthogonal directions. The mandibular condyles were retrained in all three directions, and either the left molars or incisors area were restrained from moving vertically. RESULTS: The peak von Mises stresses of structural optimized PSMRPs (264 MPa, 296 MPa) were way lower than that of the initial PSMRP design (393 MPa), with 33 and 25% reduction during left group clenching. The peak magnitude of von Mises stress, minimum principal stress, and maximum principal strain of PSMRP1 (264 MPa, 254 MPa; -297 MPa, -285 MPa; 0.0020, 0.0020) was lower than that of PSMRP2 (296 MPa, 286 MPa; -319 MPa, -306 MPa; 0.0022, 0.0020), while the peak maximum principal stress of PSMRP1 (275 MPa, 257 MPa) was higher than that of PSMRP2 (254 MPa, 235 MPa) during both left group clenching and incisal clenching tasks. CONCLUSIONS: The structural optimized PSMRPs reveal their biomechanical advantage compared with the original design. The PSMRP1 presents better biomechanical performance to the patient-specific mandibular reconstruction than PSMRP2 as a result of its superior safety, preferable flexibility, and comparable stability. The PSMRP2 provides biomechanical benefit in reducing the maximum tension than PSMRP1, indicated by lower peak maximum principal stress, through tangent arc upper margin in mandibular angle region.

Long-term survival of implant-based oral rehabilitation following maxillofacial reconstruction with vascularized bone flap.

AIM: The aim of the study was to assess the 5-year cumulative survival rate of implant-based dental rehabilitation following maxillofacial reconstruction with a vascularized bone flap and to investigate the potential risk factors which might influence the survival rate. MATERIALS AND METHODS: A retrospective cohort study was designed. Inclusion criteria involved 18 years old or above patients with the availability of clinical and radiological data and a minimum follow-up 1 year following implant placement. The cumulative survival rate was analyzed by Kaplan-Meier curves and the influential risk factors were assessed using univariate log-rank tests and multivariable Cox-regression analysis. RESULTS: 151 implants were assessed in 40 patients with a mean age of 56.43 ± 15.28 years at the time of implantation. The mean number of implants placed per patient was 3.8 ± 1.3 with a follow-up period of 50.0 ± 32.0 months. The cumulative survival at 1-, 2- and 5-years was 96%, 87%, and 81%. Patients with systemic diseases (HR = 3.75, 95% CI 1.65-8.52; p = 0.002), irradiated flap (HR = 2.27, 95% CI 1.00-5.17; p = 0.05) and poor oral hygiene (HR = 11.67; 95% CI 4.56-29.88; p < 0.0001) were at a significantly higher risk of implant failure. CONCLUSION: The cumulative implant survival rate was highest at 1st year followed by 2nd and 5th year, indicating that the risk of implant failure increased over time. Risk indicators that seem to be detrimental to long-term survival include poor oral hygiene, irradiated flap and systemic diseases.

A Retrospective Analysis of a Cohort of Patients Treated With Immune Checkpoint Blockade in Recurrent/Metastatic Head and Neck Cancer.

OBJECTIVE: The treatment approach of recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) has long been similar for all patients. Any difference in treatment strategy was only based on existing comorbidities and on preferences of the patient and the treating oncologist. The recent advance obtained with immune therapy and more specifically immune checkpoint blockade (ICB) has been a true game changer. Today, patients and physicians have a choice to omit chemotherapy. In a small subset of patients, ICB induces a very durable disease control. The subgroup of patients in which ICB without chemotherapy would be the preferential approach is still ill-defined. Yet, this evolution marks a major step towards a more personalized medicine in R/M HNSCC. MATERIALS AND METHODS: In this paper, we present a retrospective cohort study of a patient population that was treated with ICB in a single center and we analyze potential factors that are associated with outcome and may help to select patients for treatment with ICB. RESULTS: 137 consecutively treated patients were identified. Male gender and metastatic disease appeared to be associated with improved overall survival (OS). There was no correlation observed with age, number of previous treatment lines or immune target. CONCLUSION: Along with PD-L1 status defined by Combined Positive Score (CPS), clinical parameters such as site of recurrence and gender may help to define the optimal treatment strategy in R/M HNSCC.

Value of six comorbidity scales for predicting survival of patients with primary surgery for oral squamous cell carcinoma.

BACKGROUND: Comorbidities influence treatment outcome of oral squamous cell carcinoma (OSCC). This study compared the predictive performance of six comorbidity scales for overall survival after surgery for OSCC. METHODS: We retrospectively analyzed OSCC patients, surgically treated at an academic center in Belgium between January 01, 2000 and January 01, 2020. Validity of the scales was evaluated using the area under the curve (AUC) of receiver operating characteristic curves. RESULTS: Three hundred and twenty three patients were included. Elixhauser Comorbidity Index (AUC = 0.74, 95% CI: 0.55-0.92; AUC = 0.73, 95% CI: 0.55-0.80), modified Elixhauser Comorbidity Index (AUC = 0.72, 95% CI: 0.54-0.91; AUC = 0.69, 95% CI: 0.51-0.77), and Combined Comorbidity Index (AUC = 0.76, 95% CI: 0.58-0.84; AUC = 0.76, 95% CI: 0.59-0.84) were meaningful predictors for 2 and 5-year survival, respectively. CONCLUSION: Selected comorbidity scales were capable of predicting overall survival for OSCC patients 2 and 5 years after primary surgery.

Preclinical study of additive manufactured plates with shortened lengths for complete mandible reconstruction: Design, biomechanics simulation, and fixation stability assessment.

BACKGROUND: A combination of short titanium plates fabricated using additive manufacturing (AM) provides multiple advantages for complete mandible reconstruction, such as the minimisation of inherent implant deformation formed during AM and the resulting clinical impact, as well as greater flexibility for surgical operation. However, the biomechanical feasibility of this strategy is still unclear, and therefore needs to be explored. METHOD: Three different combinations of short mandible reconstruction plates (MRPs) were customised considering implant deformation during the AM process. The resulting biomechanical performance was analysed by finite element analysis (FEA) and compared to a conventional single long MRP. RESULTS: The combination of a long plate and a short plate (Design 3 [LL61 mm/RL166 mm]) shows superior biomechanical properties to the conventional single long plate (Design 1 [TL246 mm]) and reveals the most reliable fixation stability among the three designs with short plates. Compared to conventional Design 1, Design 3 provides higher plate safety (maximum tensile stress on plates reduced by 6.3%), lower system fixation instability (relative total displacement reduced by 41.4%), and good bone segment stability (bone segment dislocation below 42.1 µm) under masticatory activities. CONCLUSIONS: Preclinical evidence supports the biomechanical feasibility of using short MRPs for complete mandible reconstruction. Furthermore, the results could also provide valuable information when treating other large-sized bone defects using short customised implants, expanding the potential of AM for use in implant applications.

Application of Three-Dimensional Printed Customized Surgical Plates for Mandibular Reconstruction: Report of Consecutive Cases and Long-Term Postoperative Evaluation.

ABSTRACT: This study aims to evaluate the use of customized surgical plates in patients with mandibular defects concerning postoperative aesthetics and functional outcomes during the 2-year follow-up. Preoperative virtual surgical plans and patient-specific three-dimensional printed plates were tailored for consecutive patients. Preoperative preparation, surgical produces, postoperative aesthetics, and functional outcomes were described in detail. The average follow-up period was over 2 years. In the presented clinical cases, aesthetic and functional outcomes were reported to be satisfactory.

Biomechanical comparison of locking and non-locking patient-specific mandibular reconstruction plate using finite element analysis.

Patient-specific mandibular reconstruction plate (PSMRP), as one of the patient-specific implants (PSIs), offers a host of benefits to mandibular reconstruction. Due to the limitation of fabricating screw hole threads in the PSMRP, 3D printed PSMRP is applied to the non-locking system directly in the mandibular reconstruction with bone graft regardless of the locking system. Since the conventional manual-bending reconstruction plate (CMBRP) provides better fixation in the locking system, it needs to be validated whether the locking PSMRP performs better than the non-locking PSMRP in the patient-specific mandibular reconstruction. Thereupon, the purpose of this study was to compare the biomechanical behavior between the locking and non-locking PSMRP. Finite element analysis (FEA) was used to conduct the biomechanical comparison between the locking PSMRP and non-locking PSMRP by simulating the momentary incisal clenching through static structural analysis. Mandible was reconstructed through the virtual surgical planning, and subsequently a 3D model of mandibular reconstruction assembly, including reconstructed mandible, PSMRP, and fixation screws, was generated and meshed for the following FEA simulations. In the form of equivalent von Mises stress, equivalent elastic strain, and total deformation, the locking PSMRP demonstrated its higher strengths of preferable safety, desirable flexibility, and anticipated stability compared with the non-locking PSMRP, indicated by much lower maximum stress, lower maximum strain and equivalent displacement. Locking PSMRP/screw system provides a better fixation effect to the patient-specific mandibular reconstruction than the non-locking one as a result of its productive fixation nature. FEA plays a paramount role in pre-validating the design of PSMRP through the biomechanical behavior evaluation in static structural analysis.

Adherence to Computer-Assisted Surgical Planning in 136 Maxillofacial Reconstructions.

OBJECTIVE: To investigate the adherence to initially planned maxillofacial reconstructions using computer-assisted surgery (CAS) and to identify the influential factors affecting its compliance for maxillofacial reconstruction. PATIENTS AND METHODS: A retrospective analysis of 136 computer-assisted maxillofacial reconstructive surgeries was conducted from January 2014 to June 2020. The categorical parameters involved age, gender, disease etiology, disease site, defect size, bone flap segments, and flap type. Apart from descriptive data reporting, categorical data were related by applying the Fisher-exact test, and a p-value below 5% was considered statistically significant (P < 0.05). RESULTS: The main reasons for partial or non-adherence included unfitness, patient health condition, and other subjective reasons. Out of the total patient population, 118 patients who underwent mandibular reconstruction showed higher CAS compliance (83.9%) compared to the 18 midface reconstruction (72.2%) without any statistically significant difference (p = 0.361). Based on the size of the defect, a significantly higher CAS compliance (p = 0.031) was observed with a minor defect (80.6%) compared to the large-sized ones (74.1%). The bone flaps with two or more segments were significantly (p = 0.003) prone to observe a partial (15.4%) or complete (12.8%) discard of the planned CAS compared to the bone flaps with less than two segments. The malignant tumors showed the lowest CAS compliance when compared to other disorders without any significant difference (p = 0.1). CONCLUSION: The maxillofacial reconstructive surgical procedures offered optimal compliance to the initially planned CAS. However, large-sized defects and multiple bone flap segments demonstrated a higher risk of partial or complete abandonment of the CAS.

The Effectiveness of Surgical Methods for Trismus Release at Least 6 Months After Head and Neck Cancer Treatment: Systematic Review.

BACKGROUND: The objective of this systematic review was to identify the different surgical treatment modalities of severe trismus after head and neck squamous cell cancer treatment. METHODS: An electronic literature database search was conducted in Medline, Embase, Cochrane, Web of Science, and OpenGrey to determine articles published up to September 2021. Two observers independently assessed the identified papers for eligibility according to PRISMA guidelines. The inclusion criteria were trismus after head and neck squamous cell cancer with consecutive treatment, detailed description of the surgical procedure for trismus release, description of the initial treatment, at least 6 months between initial cancer treatment and trismus release surgery, a minimal follow-up (FU) of 6 months, and availability of full text. The quality was evaluated using the Newcastle-Ottawa scale. A subanalysis of the maximal mouth opening (MMO) was performed using a mixed-effect model. RESULTS: A total of 8,607 unique articles were screened for eligibility, 69 full texts were reviewed, and 3 studies, with a total of 46 cases, were selected based on the predetermined inclusion and exclusion criteria. Three treatment strategies were identified for trismus release (1) free flap reconstruction (FFR), (2) coronoidectomy (CN), and (3) myotomy (MT). There was a clear improvement for all treatment modalities. A quantitative analysis showed a beneficial effect of CN (mean 24.02 ± 15.02 mm) in comparison with FFR (mean 19.88 ± 13.97 mm) and MT (mean 18.38 ± 13.22 mm) (P < 0.01*). An increased gain in MMO after trismus release was found if no primary resection was performed (P = 0.014*). Two studies included in the analysis had an intermediate risk of bias and one had a low risk of bias. CONCLUSION: Currently available reports suggest a low threshold for performing a CN compared with FFR and MT. There is a need for high-quality randomized controlled trials with carefully selected and standardized outcome measures.

Long-term functional outcomes of vascularized fibular and iliac flap for mandibular reconstruction: A systematic review and meta-analysis.

INTRODUCTION: To date, there is a lack of evidence related to the long-term evaluation of recipient-site functional outcomes following mandibular reconstruction with vascularized bone grafts. Therefore, the aim of this systematic review and meta-analysis was to evaluate the long-term recipient-site functional outcomes in oral oncology patients who require mandibular reconstruction with either vascularized fibular flap (VFF) or vascularized iliac flap (VIF). METHODS: An extensive electronic search was conducted in PubMed, Web of Science, Cochrane, and Embase databases for identifying articles published until April 2020. All papers were dual screened for eligibility in accordance with the Preferred Reporting of Systematic Reviews and Meta-Analyses and Meta-analysis of Observational Studies in Epidemiology guidelines. The risk of bias was assessed using the MINORS tool. A meta-analysis of functional outcome parameters was performed to estimate single incidence rates. RESULTS: A total of 257 patients with a mean follow-up period of 38.6 ±â€¯19.5 months were included in this meta-analysis, where 174 patients underwent VFF reconstruction and 83 patients involved reconstruction with VIF. The functional outcomes in patients reconstructed with VIF showed improved scoring for mastication, deglutition, diet, and speech. Speech showed highest score among all functional parameters, whereas, mastication was the most poorly recovered parameter in relation to reconstruction with both flaps. No significant difference in functional outcomes was observed between both flaps. CONCLUSION: Current evidence seems to indicate that VIF offers improved long-term recipient-site functional outcomes. Yet, considering a high level of data heterogeneity in published studies, future long-term standardized comparative studies should be conducted.

Bovine-derived xenograft in combination with autogenous bone chips versus xenograft alone for the augmentation of bony dehiscences around oral implants: A randomized, controlled, split-mouth clinical trial.

AIM: The aim of the study was to evaluate whether the use of a xenograft is not inferior to the use of xenograft and autogenous bone chips in treating dehiscences at implant placement. MATERIALS AND METHODS: After implant placement, leaving a dehiscence, control sites were treated using a composite graft (autogenous bone chips and xenograft) and at the test sites 100% xenograft was used. Both sites were covered with a resorbable collagen membrane. Dehiscences were measured clinically at implant placement and at re-entry. CBCT was taken immediately after implant placement and after 4 months. RESULTS: In total, 28 GBR procedures were performed in 14 patients. On average, the change in vertical defect height was 2.07 mm (46.7%-test group) and 2.28 mm (50.9%-control group) (p > .05). The horizontal defect width at the implant shoulder change on average 1.85 mm (40.5%-test group) and 1.75 mm (40.9%-control group) (p > .05). On average, a loss in augmentation thickness of 0.45 mm (68.9%-test group) and 0.64 mm (55.5% control group) between implant placement and augmentation and abutment surgery was obtained at the implant shoulder. CONCLUSION: Both treatment modalities seem to work to a certain extent. At implant shoulder level, the augmentation thickness seems to be disappeared after the healing phase. (NCT03946020).

Zoledronic Acid Induces Site-Specific Structural Changes and Decreases Vascular Area in the Alveolar Bone.

PURPOSE: The aim was to assess the effect of a relevant regimen of zoledronic acid (ZA) treatment for the study of bisphosphonate-related osteonecrosis of the jaw on alveolar bone microstructure and vasculature. A sub-objective was to use 3-dimensional imaging to describe site-specific changes induced by ZA in the alveolar bone. MATERIALS AND METHODS: Five Wistar rats received ZA (0.6 mg/kg) and five (controls) received saline solution in the same volume. The compounds were administered intraperitoneally in 5 doses every 28 days. The rats were euthanized 150 days after therapy onset. The mandibles were scanned using high-resolution (14-µm) micro-computed tomography (micro-CT), decalcified, cut into slices for histologic analysis (5 µm), and stained with hematoxylin-eosin. Bone quality parameters were calculated using CT-Analyser software (Bruker, Kontich, Belgium) in 2 different volumes of interest (VOIs): the region between the first molar roots (VOI-1) and the periapical region under the first and second molars' apex (VOI-2). Blood vessel density and bone histomorphometric parameters were calculated only for the region between the roots of the first molar using AxioVision Imaging software (version 4.8; Carl Zeiss, Gottingen, Germany). RESULTS: ZA-treated rats showed a significant increase in percentage of bone volume and density (P < .05), with thicker and more connected trabeculae. Furthermore, the ZA group showed a significant decrease in the size of the marrow spaces and nutritive canals and in blood vessel density (P < .05). In the micro-CT evaluation, VOI-2 showed better outcomes in measuring the effect of ZA on alveolar bone. CONCLUSIONS: ZA treatment induced bone corticalization and decreased alveolar bone vascularization. VOI-2 should be preferred for micro-CT evaluation of the effect of bisphosphonates on alveolar bone. This analysis allowed the effect of ZA on alveolar bone and its vascularization to be characterized. The results of this analysis may add further knowledge to the understanding of the physiopathology of osteonecrosis of the jaw.

Leucocyte- and platelet-rich fibrin block for bone augmentation procedure: A proof-of-concept study.

AIM: The objective of this proof-of-concept study was to investigate the effects of a new guided bone regeneration technique with a tissue engineering approach. MATERIALS AND METHODS: This single cohort observational study evaluated the outcome of the leucocyte- and platelet-rich fibrin (L-PRF) Block for horizontal bone augmentation in the maxilla. The L-PRF Block is prepared by mixing a particulated biomaterial with chopped L-PRF membranes at a 50:50 ratio and adding liquid fibrinogen to glue all together. Horizontal augmentation was assessed linearly and volumetrically immediately after surgery and 5-8 months later by matching consecutive cone beam computed tomography (CBCTs). RESULTS: Ten patients (mean age of 50.7 years [±17.2]) representing 15 sites with horizontal alveolar deficiencies were included. Superimposition of pre-operative and posthealing CBCT scans showed an average linear horizontal bone gain of 4.6 mm (±2.3), 5.3 mm (±1.2) and 4.4 mm (±2.3), measured at 2, 6 and 10 mm from the alveolar crest, respectively. The volumetric gain was 1.05 cm3 (±0.7) on average. The resorption rate after 5-8 months was 15.6% (±6.7) on average. CONCLUSIONS: L-PRF Block may be a suitable technique to augment deficient alveolar ridges.