Abstract Background Postoperative flap monitoring following microvascular head and neck reconstruction can be conducted by continuous flap tissue perfusion measurement with an attached surface probe using the Oxygen-to-see (O2C) analysis system. However, intravenously administered norepinephrine may influence flap tissue perfusion and affect the reliability of predefined absolute thresholds used for the detection of vascular flap compromise. This study aimed to evaluate the association between early postoperative flap tissue perfusion and norepinephrine in radial free forearm flaps (RFFF). Methods Data of patients undergoing head and neck reconstruction with an RFFF from 2020 until 2022 were retrospectively analyzed. Flap tissue perfusion was measured continuously for 8 h postoperatively with an attached surface probe using the O2C analysis system. Intravenously administered norepinephrine dose and blood flow and hemoglobin oxygen saturation as well as flow resistance (ratio of mean arterial blood pressure and flap blood flow) were analyzed for associations. Results The study included 12 patients (5 men and 7 women). Blood flow and hemoglobin oxygen saturation were not associated with norepinephrine (B=-110.509, p = 0.583 and B=-12.500, p = 0.912). In addition, flow resistance was not associated with norepinephrine (B = 0.292, p = 0.825). Conclusions Early postoperative tissue perfusion of RFFFs, measured during continuous flap monitoring with attached surface probes for the O2C analysis system, showed no association with norepinephrine with regard for blood flow and hemoglobin oxygen saturation. This supports the reliability of absolute thresholds used to detect vascular flap compromise during continuous postoperative monitoring of RFFFs with the O2C analysis system, albeit additional studies with substantial sample sizes and longer monitoring intervals are required to validate these findings.

The safety of pediatric surgery in cleft patients is an important topic, since complication rates can be influenced by many factors. The aim of this study was to evaluate perioperative factors and their influence on postoperative respiratory events in cleft lip and palate patients undergoing palatoplasty. The study included healthy patients (ASA I and II) with unilateral and bilateral cleft lip and palate and isolated cleft palate (n = 52) undergoing palatoplasty at the age of 390 (130) days, with a medium cleft palate size of 8 (8) mm. One group with respiratory complications (RC: n = 7) and a second group with no complications (NC: n = 45) were compared regarding perioperative factors, such as preoperative blood values and intraoperative course (temperature, blood pressure (RR), O2 saturation and operation time). A total complication rate of 13.5% was observed. None of the examined factors was significant. However, the fact that the RC group had a longer total anesthesia time could point to a possible cause or contributing factor. Since the working field of the anesthesiologist changes during the operation, we recommend a clear interdisciplinary collaboration between surgeons and anesthesiologists, and keeping operation times as short as possible.

INTRODUCTION:An adequate gingiva model for dental students has special requirements, such as strength, flexibility and a periosteum. As there is a lack of available models, the aim of this study was to develop a new and sufficient gingiva model that fits students' needs. METHODS:We developed various gingiva models and compared them to a previously used model at different stages of student development. Oral surgeons (n = 10) and dental students (3rd year: n = 13; 4th year: n = 11; 5th year: n = 11) tested and evaluated four model designs with various materials, both with and without periosteum and with and without a punch (models 1-4). RESULTS:Both oral surgeons and dental students liked the model with periosteum and simulated alveolus best, citing that it delivers the most options for practicing, is the most realistic, and helps to improve their own skills. All participants performed similarly on the practice, with a tendency toward better performance in groups with more experience. CONCLUSION:We recommend the use of our periosteum model with and without punches for preclinical and clinical dental students, as it is easy to produce and delivers multiple design opportunities according to the level of experience and students' needs.

Introduction Intravenously administered propofol and sufentanil may affect radial free forearm flap (RFFF) tissue perfusion and interfere with early postoperative continuous flap monitoring based on flap tissue perfusion measurement. This study aimed to investigate the influence of both medications on RFFF tissue perfusion. Materials and methods Eight patients who underwent head and neck reconstruction with an RFFF between 2020 to 2022 were retrospectively analyzed. Flap blood flow and hemoglobin oxygen saturation, measured continuously with an attached surface probe using the Oxygen-2-See analysis system for 8 hours postoperatively, and flap flow conductance (ratio of blood flow and mean arterial blood pressure) were analyzed for associations with intravenously administered doses of propofol and sufentanil. Results The flap tissue perfusion parameter hemoglobin oxygen saturation showed a positive association with propofol (B=37.748, p=0.018), which persisted upon controlling for absolute and relative systolic, diastolic, and mean arterial blood pressure values and norepinephrine and sufentanil doses (all p<0.05). No other associations between flap tissue perfusion parameters and propofol or sulfentanil were observed (all p>0.05). Conclusion Tissue perfusion of RFFFs was generally not associated with intravenously administered propofol or sulfentanil. The observed association in terms of hemoglobin oxygen saturation and propofol should be confirmed in further prospective studies with larger study cohorts and longer study intervals with regard to an interference with early postoperative continuous monitoring of RFFFs after head and neck reconstruction.

To evaluate the effect of the implant material-either titanium or zirconia-on the development of bacterial deposits. In this one-year prospective split-mouth study, 20 patients with an edentulous lower jaw were treated with two zirconia and two titanium implants. Clip attachments were used for the removable denture. During the follow-up period, fluid samples were taken from around each patient's implants and natural teeth to analyze the microbiota using DNA isolation, amplicon sequencing, and downstream analysis. Between the different time points, for the titanium material, the relative abundance of Actinomyces israelii increased significantly (p = 0.009) after 12 months when compared with the baseline. When comparing the different time points for each material, a significant decrease in the phyla Fusobacteria (p = 0.03) and Proteobacteria (p = 0.03) after six months versus baseline was detected for only zirconia, whereas the abundance of Firmicutes was significantly increased (p = 0.03). When comparing the different materials at each time point, the phylum Actinobacteria was found to be less abundant after 12 months on the zirconia implants than on the titanium implants (p = 0.04). By contrast, on the zirconia material, the relative abundance of the genus Leptotrichia decreased significantly after six months when compared with the baseline, while no significant changes in terms of this genus were found for the titanium implants or teeth over time. Zirconia tended to show less abundant bacterial deposits over time. The microbial diversity was lower on the titanium implants than on the ceramic material after 12 months. In addition, after 12 months of evaluation, neither the teeth nor the implants showed similar prevalences or levels of the target species.

The aim of this retrospective study was to evaluate implant stability using resonance frequency analysis (RFA) (Osstell® W H, Mettmann) for autologous one-stage sinus floor elevation with implantation and provide advice regarding the healing procedure and the timing of implant loading. After 3 months, 145 implants were evaluated for secondary implant stability using RFA. Of the evaluated implants, 72 were set in original bone (OB) in the upper posterior jaw, 21 were set in combination with a one-stage autologous external sinus floor elevation (EE), and 52 in combination with internal elevation (IE). Osseointegration was significantly higher in OB (94,4

Aim: This study aimed to compare two-piece zirconia and two-piece titanium implants inserted into the anterior mandible for removable overdentures in a 3-year randomized split-mouth clinical trial. Methods: Twenty fully edentulous mandibular patients received two zirconia and two titanium implants allocated by computer-generated randomization. The primary endpoint was bleeding-on-probing (BOP) at 12 months. Secondary outcomes included implant survival and success (Albrektsson criteria), marginal bone level changes, peri-implant cytokines (IL-1β, IL-6, and TNFα), prosthetic complications, and patient-reported outcomes (PROMs). Results: After 3 years, overall survival was 98.61% and overall success was 84.72%. Titanium implants showed higher success compared with zirconia implants (91.70% vs. 77.78%), while survival was 100% and 97.22%, respectively. Marginal bone loss was significantly greater around zirconia implants at 36 months (p < 0.01). No significant differences were observed in IL-1β, IL-6, or TNFα levels up to 12 months. PROMs revealed a trade-off, with zirconia favored for esthetics and cleaning perception, while titanium was rated superior for stability. Conclusions: Within the limitations of this split-mouth RCT, zirconia implants demonstrated reduced success and inferior marginal bone stability compared with titanium implants in overdenture therapy. Careful case selection and close follow-up appear essential when zirconia implants are used in this indication.

The Oxygen-2-see (O2C) analysis system can measure flap perfusion, which is a prerequisite for flap viability, and it is therefore commonly used in flap monitoring for microvascular head and neck reconstruction. However, in the context of predefined threshold values for perfusion parameters indicating vascular flap compromise, it is unclear whether blood hemoglobin and hematocrit levels are confounding variables. The aim of this study was to investigate the influence of blood hemoglobin and hematocrit levels on flap perfusion parameters. Perfusion parameters (i.e., flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation) measured intraoperatively and postoperatively with the O2C analysis system at 8- and 2-mm tissue depths were retrospectively analyzed in 125 patients reconstructed with a radial free forearm flap (RFFF), an anterolateral thigh flap (ALTF), or a fibula free flap (FFF) between 2011 and 2020. Associations between perfusion parameters and blood hemoglobin and hematocrit levels were analyzed using Spearman correlation coefficient and multiple linear regression models. Postoperative hemoglobin concentration at a 2-mm tissue depth was associated with blood hemoglobin and hematocrit levels in RFFFs (r = 0.259, p = 0.031; and r = 0.268, p = 0.026; respectively). Both associations persisted in multivariable regression analysis (p = 0.040 and p = 0.036). No other associations between perfusion parameters and blood hemoglobin and hematocrit levels were observed for RFFFs, ALTFs or FFFs (all p > 0.05). For the perfusion parameters flap blood flow and hemoglobin oxygen saturation no association with blood hemoglobin or hematocrit levels was observed. This underlines the validity of absolute threshold levels for indicating vascular flap compromise in the context of flap monitoring with the O2C analysis system.

Introduction:Postoperative flap monitoring in microvascular head and neck reconstruction based solely on flap tissue perfusion measurements relative to predefined thresholds may be influenced by systemic tissue perfusion alterations. This study compared flap and contralateral donor site tissue perfusion and evaluated the utility of the flap-to-donor site ratio in detecting vascular flap compromise. Materials & methods:Tissue perfusion measured with the O2C analysis system at a tissue depth of 3 mm at 0, 12, 24, 36, and 48 h postoperatively was retrospectively analyzed in 62 patients who underwent head and neck reconstruction with a fasciocutaneous free flap (FFF) (radial free forearm flap) or a perforator free flap (PFF) (anterolateral thigh flap or fibula free flap) between 2020 and 2022. Flap and contralateral donor site tissue perfusion parameters (blood flow, hemoglobin concentration, and hemoglobin oxygen saturation) were compared, and flap-to-donor site ratio cut-off values indicating vascular flap compromise, based on the minimum (blood flow and hemoglobin oxygen saturation) or maximum (hemoglobin concentration) value of all 5 measurement timepoints, were determined. Results:Blood flow, hemoglobin concentration, and hemoglobin oxygen saturation were in general higher at the flap than the donor site (p < 0.05). Cut-off values for the flap-to-donor site ratio indicating vascular flap compromise were as follows for FFFs and PFFs, respectively: <1.063 and <0.224 for blood flow, >1.792 and >1.597 for hemoglobin concentration, and <0.673 and <0.199 for hemoglobin oxygen saturation (sensitivity all 100 % [confidence interval (CI) range 2.5-100.0 %]; specificity all >65 % [CI range 49.0-100.0 %]). Conclusion:The postoperative course of tissue perfusion differs between flap and contralateral donor sites in FFFs and PFFs. The flap-to-donor site ratio could be used to detect vascular flap compromise in microvascular head and neck reconstruction, with further studies needed to confirm the determined cut-off values for the flap-to-donor site ratio indicating vascular flap compromise.

This study investigated the sensory recovery of microvascular free flaps in the oral cavity with functional magnetic resonance imaging (fMRI) to assess the activation in the primary sensory cortex (S1). The study included 20 patients with sensory recovery at the flap site in the tongue and/or mouth floor after ablative cancer surgery that involved unilateral resection of the lingual nerve and reconstruction with a radial free forearm flap, anterolateral thigh flap or lower leg perforator flap without nerve readaptation between 2012 and 2019. The control non-flap and contralateral flap sites were electrically stimulated with a patient-specific, sensation-inducing voltage for 10 min with 30s on/off intervals. During this process, a fMRI was conducted simultaneously to assess the signal area and level in S1. The stimulation voltage was higher at the flap site than at the control non-flap site (6.0 V vs. 3.0 V, p<0.001). The signal area activated upon stimulation of the flap and control non-flap sites was located in the cortical area representing the lingual nerve. The signal level in S1 upon stimulation of the flap site was similar to that upon stimulation of the control non-flap site (3.2 T vs. 3.5 T, p=0.751). Activation of the cortical area representing the lingual nerve upon stimulation of the flap site implies that sensory recovery of microvascular free flaps in the tongue and mouth floor region involves nerve ingrowth from the remaining lingual nerve into the flap tissue.

Orbital exenteration (exenteratio orbitae) is a disfiguring procedure performed with tumor resection. Rapid realization of an implant-retained craniofacial prosthesis with a secure fit for an active life is essential to restore quality of life. Osseointegrated implants are commonly used for maxillofacial rehabilitation. The precise positioning of these implants is more difficult in cases of reduced bone availability, but it enables anaplastologists to achieve an unobtrusive restoration. After computed tomography (CT) scans of 13 cadaver heads, 104 craniomaxillofacial (CMF) implants were digitally planned. Using a split-face study design, one periorbital side was treated with customized surgical guides and one side was operated freehand. The digital evaluation of position, axis, and insertion depth compared to the digital planning was conducted for 78 periorbital implants using digital evaluation of a postoperative CT scan to measure the linear and angular deviation from preoperative planning. The linear deviation in 3D (p = 0.0105), drilling depth (p = 0.0013), and angular deviation (p = 0.0004) were significantly greater in the freehand group than in the guided computer-assisted implant surgery (CAIS) group. Digital planning enables the available bone support to be preoperatively estimated. CAIS with surgical guides offers significantly more accurate results for CMF implant placement than a freehand transfer of digital planning. Guided CAIS requires a larger surgical approach and therefore fails to achieve the goal of a minimally invasive technique.

ObjectivesThe aim of this study was to identify high-risk dental extractions in patients taking antiplatelet (AP) medication or anticoagulants (ACs) and to compare an experienced surgeon's decisions with machine learning (ML) algorithms.Materials and methodsOur study included 2000 procedures, of which 1788 were conducted in patients under monotherapy with AP medication, vitamin K antagonists (VKAs), heparin, or direct oral anticoagulants (DOACs), 426 were performed under dual therapy, and 27 under triple therapy. Four algorithms, logistic regression (LR), eXtreme gradient boost (XGB), random forest (RF), and K-nearest neighbors (KNN), were trained with 80% (1600 procedures) of the derived data. Afterwards, an experienced oral surgeon and the algorithms were tested on the remaining 20% (400 procedures) of the data to evaluate the predictive power with respect to bleeding incidents.ResultsThe incidence of hemorrhagic events was low (4.35%). Dual anticoagulation significantly affected the risk of bleeding. Evaluating the results of the predictions, all four algorithms outperformed the surgeon in terms of balanced accuracy (LR: 58%; RF: 59%; XGB: 61%; KNN: 62%; surgeon: 53%).ConclusionsDecision-making based on various parameters influencing bleeding risk is complex, and surgeons tend to overestimate this risk. Both the algorithms and the surgeon had a share of false positive predictions; however, in a medical context, preventive overcaution does less damage than underestimation.Clinical relevanceAlgorithms can provide an objective assessment of bleeding risk and help determine risk profiles, uncover variables with the highest predictive power, and serve as guidance on postoperative observation periods.Trial registrationThis study was approved by the Ethics Committee of the Medical Faculty of RWTH Aachen (Decision Number 24-353). This was a retrospective clinical study designed to analyze postoperative bleeding after dental extractions in patients under antithrombotic medication and to evaluate the prediction of bleeding events by different algorithms and human experience.

The free fibular flap (FFF) is a standard procedure for the oral rehabilitation of segmental bone defects in the mandible caused by diseases such as malignant processes, osteonecrosis, or trauma. Digital guides and computer-assisted surgery (CAS) can improve precision and reduce the time and cost of surgery. This study evaluates how different designs of slot cutting guides, guiding heights, and cutting instruments affect surgical accuracy during mandibular reconstruction. Ninety model operations in a three-part fibular transplant for mandibular reconstruction were conducted according to digital planning with three guide designs (standard, flange, and anatomical slots), three guide heights (1 mm, 2 mm, 3 mm), and two osteotomy instruments (piezoelectric instrument and saw). The cut segments were digitized using computed tomography and digitally evaluated to assess surgical accuracy. For vestibular and lingual segment length, the anatomical slot and the flange appear to be the most accurate, with the flange slightly under-contoured vestibularly and the standard slot over-contoured lingually and vestibularly (p < 0.001). There were only minor differences between the use of saw and piezoelectric instrument for lingual (p = 0.005) and vestibular (p < 0.001) length and proximal angle (p = 0.014). The U-distance after global reconstruction for flanges resulted in a median deviation of 0.0468 mm (IQR 8.15), but was not significant (p = 0.067). Anatomical slots and flanges are recommended for osteotomy, with guiding effects relying on both haptic and visual control. Unilateral guided flanges also work accurately at high guidance heights. The results of piezoelectric instrument (PI) and saw showed comparable results in the assessment of individual segments and U-reconstruction in this in vitro study without soft tissue, so that the final decision is left to the expertise of the surgeons.

Against the background of digitalization, practicing on 3-D models for dental education has become more important. To improve the surgical skills of dental students, this study aimed to develop a 3-D-printed model for osteotomy of a partially retained lower wisdom tooth and evaluate surgical skills of students with practical experience acquired through phantom exercises compared to students who acquired experience only by assisting oral surgeons. We developed a 3-D model that allows dental students to perform an osteotomy of a partially retained real wisdom tooth in region 48. The model was evaluated by oral surgeons (OS; n = 5), students with phantom experience (PE; n = 26), and students with experience with clinical assistance (CE; n = 29). Additionally, student performance was rated. The OS, PE, and CE groups all evaluated the model as suitable for student courses, except for the gingiva mask. The CE group developed slightly better. In the exercise, the PE group showed better incision results, while the CE group was slightly better in the preparation of the working field. The osteotomy model is suitable for hands-on courses for dental students, but the gingiva should be improved. However, phantom exercise cannot replace clinical experience. To improve education, knowledge and self confidence of students in dental school.

BACKGROUND:The prediction of postoperative flap revision by intraoperative flap perfusion measurement in microvascular head and neck reconstruction could improve postoperative flap monitoring. PURPOSE:The study purpose was to measure the association between intraoperative flap perfusion and postoperative flap revision. STUDY DESIGN, SETTING, SAMPLE:This study was conducted as a retrospective cohort study at the Department of Oral and Maxillofacial Surgery at the University Hospital RWTH Aachen, Germany. The sample was composed of subjects reconstructed with anterolateral thigh flaps or fibula free flaps in the head and neck region between 2011 and 2022. Exclusion criteria were an age below 18 years, incomplete data records, and flap revision within 12 hours postoperatively. PREDICTOR VARIABLE:The predictor variable was flap perfusion measured intraoperatively as blood flow, hemoglobin concentration, and hemoglobin oxygen saturation. MAIN OUTCOME VARIABLE:The main outcome variable was postoperative flap revision coded as yes or no. COVARIATES:Covariates were sex, age, flap type, flap ischemia duration, mean arterial blood pressure, and catecholamine dose. ANALYSES:Covariates were compared for perfusion parameters by Mann-Whitney test. Subjects with and without flap revision were compared for covariates by χ2 test or Mann-Whitney test and for perfusion parameters by Mann-Whitney test and multivariable regression analysis, and cut-off values for predicting flap revision were determined using receiver operating characteristics. P > .05 was considered significant. RESULTS:The sample (median age 66 [interquartile range 18] years) was composed of 239 (93%) subjects without and 18 (7%) subjects with flap revision. Blood flow at 8 mm and hemoglobin oxygen saturation at 2 mm tissue depth were lower, and hemoglobin concentration at 8 mm tissue depth was higher in subjects with flap revision (P = .008; P = .030; P = .001). The cut-off values for blood flow, hemoglobin oxygen saturation, and hemoglobin concentration for predicting flap revision were <76.5 arbitrary units, <64.5%, and >34.5 arbitrary units (area under the curve 0.687, 0.653, 0.728; P = .10, P = .014, P < .001; sensitivity 72, 89, 83%; specificity 70, 44, 53%; positive predictive value 15, 11, 12%; negative predictive value 97, 98, 98%). CONCLUSION AND RELEVANCE:Intraoperative flap perfusion was associated with postoperative flap revision related to cut-off values (highest predictive accuracy for blood flow). Prospective confirmatory studies are necessary.

Mandibular reconstruction following continuity resection due to tumor ablation or osteonecrosis remains a significant challenge in maxillofacial surgery. Virtual surgical planning (VSP) relies on accurate segmentation of the mandible, yet existing AI models typically include teeth, making them unsuitable for planning of autologous transplants dimensions aiming for reconstructing edentulous mandibles optimized for dental implant insertion. This study investigates the feasibility of using deep learning-based segmentation to generate anatomically valid, toothless mandibles from dentate CT scans, ensuring geometric accuracy for reconstructive planning. A two-stage convolutional neural network (CNN) approach was employed to segment mandibles from computed tomography (CT) data. The dataset (n = 246) included dentate, partially dentate, and edentulous mandibles. Ground truth segmentations were manually modified to create Class III (moderate alveolar atrophy) and Class V (severe atrophy) models, representing different degrees of post-extraction bone resorption. The AI models were trained on the original (O), Class III (Cl. III), and Class V (Cl. V) datasets, and performance was evaluated using Dice similarity coefficients (DSC), average surface distance, and automatically detected anatomical curvatures. AI-generated segmentations demonstrated high anatomical accuracy across all models, with mean DSCs exceeding 0.94. Accuracy was highest in edentulous mandibles (DSC 0.96 ± 0.014) and slightly lower in fully dentate cases, particularly for Class V modifications (DSC 0.936 ± 0.030). The caudolateral curve remained consistent, confirming that baseline mandibular geometry was preserved despite alveolar ridge modifications. This study confirms that AI-driven segmentation can generate anatomically valid edentulous mandibles from dentate CT scans with high accuracy. The innovation of the work is the precise adaptation of alveolar ridge geometry, making it a valuable tool for patient-specific virtual surgical planning in mandibular reconstruction.

Presurgical infant orthopedics (PSIO) is the first step in the treatment of cleft lip and palate (CLP) and is designed to approximate the cleft segments as effectively as possible before surgical reconstruction of the lip and palate. The biomechanical efficacy of different PSIO approaches in transferring molding forces to the CLP is unknown. This study aimed to define the biomechanical principles of competing PSIO techniques in a real cleft finite element (FE) model. Active intraoral (Latham), passive alveolar molding (PAM), and extraoral (DynaCleft) molding forces were virtually applied to a real cleft FE model. In the cleft region, PAM (P < 0.001) and Latham (P < 0.05) exerted significantly less stress than DynaCleft. Intraoral molding forces acted primarily at the site of the force initiation without being accompanied by high loads in the midface. PAM showed a tendency toward a better flow behavior of the molding forces than Latham. Extraoral molding transferred high stresses to the cleft, alveolar ridge, and midface. Intraoral passive molding was ultimately characterized by the highest biomechanical efficacy and showed the most favorable load distribution of all of the PSIO approaches considered in this study. Future research is needed to validate the findings against clinical data.

The Oxygen-to-see (O2C) analysis system is used for flap monitoring based on predefined threshold values for flap perfusion. However, flap size may be a confounding variable. The aim of this study was to investigate the relationship between flap size and flap perfusion in microvascular head and neck reconstruction. Flap perfusion values measured with the O2C analysis system between 2011 and 2020 in 252 patients undergoing microvascular head and neck reconstruction with a radial free forearm flap (RFFF) or anterolateral thigh flap (ALTF) were retrospectively analyzed. Intraoperative and postoperative flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation at 8- and 2-mm tissue depths were compared between small (≤ median flap size) and large flaps (> median flap size) for RFFFs and ALTFs separately. Intraoperative and postoperative hemoglobin concentration at a 2-mm tissue depth differed between small and large ALTFs (65.0 arbitrary units [AU] vs. 51.0 AU, p = 0.007; and 51.5 AU vs. 39.0 AU, p = 0.019). Both differences persisted in multivariable analysis (p < 0.001 and p = 0.012). Other differences were not observed or did not persist in multivariable analysis for RFFFs and ALTFs (all p > 0.05). Microvascular free flap perfusion is not related to flap size in terms of flap blood flow and hemoglobin oxygen saturation. This underscores the validity of predefined absolute threshold values in the context of flap monitoring based on perfusion measurement with the O2C analysis system. Flap perfusion measurement with the Oxygen-to-see (O2C) analysis system can be used for flap monitoring of small and large flaps.

Regeneration of jawbone defects poses major challenges. The combination of dental pulp stem cells (DPSCs) or DPSC-derived extracellular vesicles (EVs) with bone substitute materials shows promising potential for bone tissue engineering in vitro. This study evaluated the in vivo bone regeneration potential of DPSCs and EVs with bone graft substitutes in a novel intrabony defect model. DPSCs were isolated from 35 male Sprague–Dawley rat incisors, and EVs were collected from the cell culture medium. DPSCs were seeded onto alloplastic and xenogeneic bone graft materials and implanted into bone defects. Control groups received bone substitutes without DPSCs or EVs. Micro-computed tomography (µCT) was performed at 12 and 24 weeks post-implantation to assess bone volume (BV), bone density (BD), trabecular thickness (Tr.Th), bone growth rate (BGR), and bone-to-mineral ratio (BMR). Both graft types increased BV and BD, with no significant differences between them. Tr.Th increased across all treatments after 24 weeks, indicating ongoing bone remodeling. Notably, xenogeneic grafts combined with DPSCs and EVs significantly improved BGR (p = 0.034) and BMR (p = 0.021) compared to alloplastic grafts with DPSCs. Xenogeneic bone grafts combined with DPSCs and EVs appear to be a promising approach for bone regeneration of alveolar bone defects.

BACKGROUND:This study investigated sensory recovery of microvascular free flaps in the oral cavity with functional magnetic resonance imaging to assess activation in the primary sensory cortex (S1). METHODS:The study included 20 patients with sensory recovery at the flap site in the tongue or floor of mouth after ablative cancer surgery that involved unilateral resection of the lingual nerve and reconstruction with a radial free forearm flap, anterolateral thigh flap, or lower leg perforator flap without nerve readaptation between 2012 and 2019. Control nonflap and contralateral flap sites were electrically stimulated with a patient-specific, sensation-inducing voltage for 10 minutes with 30-second on/off intervals. During this process, functional magnetic resonance imaging was conducted simultaneously to assess the signal area and level in S1. RESULTS:The stimulation voltage was higher at the flap site than at the control nonflap site (6.0 versus 3.0 V; P < 0.001). The signal area activated upon stimulation of the flap and control nonflap site was located in the cortical area representing the lingual nerve. The signal level in S1 upon stimulation of the flap site was similar to that upon stimulation of the control nonflap site (3.2 versus 3.5 T; P = 0.751). CONCLUSION:Activation of the cortical area representing the lingual nerve upon stimulation of the flap site implies that sensory recovery of microvascular free flaps in the tongue and floor of mouth region involves nerve ingrowth from the remaining lingual nerve into the flap tissue.