Marie Sophie Katz

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.

Objectives: The 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 methods: Our 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. Results: The 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%). Conclusions: Decision-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 relevance: Algorithms 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 registration: This 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.

Background: The aim of this systematic review was to evaluate whether laser Doppler flowmetry (LDF) as a diagnostic tool is effective in detecting gingival inflammation. Methods: This review was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and registered at the International Prospective Register of Systematic Reviews (PROSPERO) (registration number CRD42025633576). Two authors independently performed searches in PubMed, Embase, the Cochrane Library, and Scopus. Results: In total, 1317 studies were identified, of which 10 met the inclusion criteria after full-text screening. All studies compared perfusion with a healthy control group, seven included a gingivitis group, five included patients with periodontitis, and none included patients with peri-implant disease. Higher blood flow values were found in patients with chronic gingivitis compared to healthy controls, while patients with experimental gingivitis showed no significant difference. Blood flow values in patients with periodontitis showed controversial results. Conclusions: LDF shows potential utility in detecting chronic gingival inflammation and altered perfusion patterns between healthy individuals and those with gingival or periodontal inflammation. However, reliably grading perfusion across disease stages and distinguishing between acute gingivitis and chronic periodontitis remains challenging. Notably, there is a lack of data regarding the use of LDF in peri-implant tissues, representing a significant gap in current research. At present, established clinical parameters such as probing depth and bleeding on probing (BOP), remain the gold standard in routine periodontal diagnostics.

Objectives: This study aimed to evaluate and compare the early healing of fresh alveolar sockets treated with or without platelet-rich fibrin (PRF) using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS). The primary outcome was gingival perfusion; secondary outcomes included clinical wound healing (based on the Landry Wound Healing Index) and patient-reported postoperative pain. Materials and methods: Sixty-two patients requiring single tooth extraction were randomized into two groups. In the PRF group, an advanced PRF (A-PRF+) plug was placed in the socket before suturing; in the control group, only suturing was performed. Gingival perfusion was measured at four sites preoperatively and on postoperative days 3 and 10 using LDF-TS. Patients rated pain, and wound healing was clinically assessed. Twelve patients were lost to follow-up, leaving 50 for analysis. Results: No significant differences were found between the PRF and control group regarding pain (day 3: p = 0.654; day 10: p = 0.329) or wound healing (day 3: p = 0.178; day 10: p = 0.595). Perfusion parameters also showed no significant group differences between baseline and day 10: oxygen saturation (SO₂: p = 0.884), relative hemoglobin (rHb: p = 0.387), and blood flow (p = 0.072). Conclusions: Gingival perfusion showed no significant group differences over 10 days. PRF did not significantly reduce pain or improve wound healing. Clinical relevance: PRF does not appear to significantly enhance healing, pain reduction, or perfusion in simple extractions. Future studies should use split-mouth designs and focus on more complex surgeries to better evaluate PRF’s effects. Trial registration: All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was performed according to the Consolidated Standards of Registered Trial (CONSORT) guidelines. The study was approved by the institutional Clinical Research Ethics Committee (Decision Number 23–105) and by the German Clinical Trials Register (File Number DRKS00032344, registered on October 11, 2023).

Purpose: The influence of blood pressure on microvascular free flap perfusion is not fully understood and remains an ongoing topic of debate, as flap perfusion is both a prerequisite for flap viability and a parameter frequently used for postoperative flap monitoring. The aim of this study was to investigate the influence of blood pressure on microvascular free flap perfusion. Methods: Perfusion measurement data obtained with the Oxygen-2-see (O2C) analysis system intraoperatively and postoperatively in 244 patients who underwent microvascular reconstruction of the head and neck region with a fasciocutaneous free flap (FFF) or perforator free flap (PFF) between 2011 and 2020 were analyzed retrospectively. Blood pressure values (i.e., systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MBP)) and perfusion parameters (i.e., flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation) were evaluated to reveal potential associations. Results: Postoperative flap blood flow was associated with SBP, DBP, and MBP in PFFs ( r = 0.245, p = 0.006; r = 0.239, p = 0.008; r = 0.295, p < 0.001, respectively). These associations also persisted in multivariable analysis ( p = 0.036; p = 0.024; p = 0.004, respectively). Postoperative hemoglobin oxygen saturation was associated with SBP and MBP in PFFs ( r = 0.253, p = 0.005; r = 0.189, p = 0.036, respectively). The association with SBP also persisted in multivariable analysis ( p = 0.005). Conclusion: Microvascular free flap perfusion in PFFs, specifically postoperative flap blood flow and hemoglobin oxygen saturation, is influenced by blood pressure. This suggests that blood pressure might be an adjustable variable for the control of flap perfusion and should be considered as a confounding variable for flap monitoring based on flap perfusion in PFFs.

Introduction: The aim of this study was to evaluate perfusion parameters and clinical features of healthy implants and implants affected by peri‐implant disease in patients who had undergone microvascular jaw reconstruction.Methods: A total of 25 patients with 92 implants placed in microvascular transplants were included. Of these, 68 implants showed healthy peri‐implant tissue, 12 were affected by peri‐implant mucositis, and 12 were diagnosed with peri‐implantitis. Peri‐implant perfusion was measured mesially and distally at the implant shoulder using laser Doppler flowmetry and tissue spectrophotometry (LDF‐TS), followed by a clinical evaluation, including measurement of probing depths, bleeding on probing (BOP), plaque index, biotype, type of implant, the restoration and the presence of keratinized tissue. Perfusion parameters were compared between the healthy implants and the implants with peri‐implant disease based on the conventional BOP–based diagnosis of peri‐implantitis, and the associations between the perfusion values and clinical measurements were analyzed. Optimal cut‐off values for predicting peri‐implantitis were calculated with receiver operating characteristics.Results: The mean relative amount of hemoglobin and mean blood flow were significantly different between healthy implants and implants with peri‐implant mucositis and peri‐implantitis (p = 0.003 and p = 0.002, respectively). However, there are interindividual differences that appear to influence blood flow values as well. When a linear mixed regression model was applied, including the patient as a random variable, the difference in blood flow was no longer statistically significant (p = 0.400). Still, the optimal cut‐off value of mean blood flow for predicting peri‐implantitis was determined to be > 46.5 AU (AUC = 0.788; p < 0.001; CI = 0.695–0.881; sensitivity = 1.00, specificity = 0.60).Conclusion: Implants in microvascular flaps are particularly vulnerable to peri‐implant disease. Risk factors are the lack of keratinized peri‐implant tissue, fixed restorations, bone‐level implants, and high plaque levels.As a noninvasive and objective method, LDF‐TS can contribute to risk assessment by evaluating perfusion parameters and help detect the early onset of peri‐implant disease.

Objectives: At 31%, the risk of postoperative bleeding after tooth extraction is particularly high in patients who receive rivaroxaban therapy. The aim of this rodent study was to compare the hemostyptic properties and gingival healing between novel polyurethane‐based adhesive VIVO and gelatin sponge (GESP) under ongoing rivaroxaban therapy over a period of 10 days. Materials: In total, 120 extractions of the first upper molar were proceeded in rodents treated with rivaroxaban. Of these, 60 postextraction sites were treated with VIVO and 60 with GESP. The duration of the surgical procedure and the clinical parameters of postoperative bleeding and wound evaluation score were recorded. In vivo fluorescence imaging and laser Doppler flowmetry and tissue spectrophotometry (LDF‐TS) were performed. Results: GESP provided a faster procedure at 1:06 ± 0:17 min, but postoperative bleeding time was significantly shorter in VIVO sockets at 1:39 ± 0:03 min. Nonsignificant mild bleeding events and comparable wound evaluation scores were recorded in both treatments. LDF‐TS showed a significant increase in mean oxygen saturation SO ₂ (%) and mean blood flow (AU) for both treatments. Only GESP showed a significant increase in relative hemoglobin (rHb). Conclusion: In the context of a rodent study, VIVO showed favorable hemostasis and promising gingival healing properties postextraction under ongoing rivaroxaban therapy.

Background: The aim of this retrospective study was to identify high-risk dental extraction patients and the timing of postoperative hemorrhage to evaluate whether preventive hospitalization should be considered in patients on antiplatelet medication (AP) or anticoagulants. Methods: Our study included 1595 procedures; 1319 were conducted under monotherapy (Group I: AP; Group II: indirect oral anticoagulant [IAC]; Group III: direct oral anticoagulant [DOAC]) and 276 under dual therapy (Group IV: double AP; Group V: AP and IAC; Group VI: AP and DOAC). We evaluated the incidence, frequency and timing of hemorrhage, hospitalization rate, and treatment of bleeding incidents. Results: The incidence of hemorrhagic events was significantly higher in the dual therapy groups compared to the monotherapy groups (p < 0.001). Comparing the procedures under monotherapy, those on DOAC (Group III) had a significantly higher risk of postoperative bleeding than Groups I and II (p < 0.001) and a higher rate of repeated bleeding episodes (p = 0.035). Regarding bleeding incidents, 44% (dual therapy) vs. 51.1% (monotherapy) occurred on the day of surgery. Conclusions: The bleeding risk after dental extractions is overall low and patients were often hospitalized preventively due to their comorbidities rather than actual bleeding risk. Patients should be instructed about local compression, and surgeries should be completed in the morning to avoid emergency visits. However, patients with cardiovascular diseases and dual therapy had a higher risk of postoperative hemorrhage. Thus, hospitalization is to be considered in these cases. Trial registration: The study was approved by the Ethics Committee of the Medical Faculty of RWTH Aachen (Decision Number 24-136). This was a retrospective clinical study designed to analyze postoperative bleeding and hospitalization rates after dental extractions in patients on AP or anticoagulation therapy.

Objectives: The topical application of hyaluronic acid after injury may accelerate the wound healing process. We aimed to retrospectively investigate whether the topical application of hyaluronic acid on standardized wounds after split-thickness skin graft removal on the thigh would accelerate wound healing and improve scarring outcomes. Additionally, we aimed to evaluate the usefulness of three-dimensional (3D) scanning to assess scars. Methods: The wound healing process of a hyaluronan group (n = 20) and a control (n = 21) were analyzed and evaluated using 3D scans at 7 and 14 days and 1, 3, and 6 months post-operatively. Scar evaluations by the patients were conducted 6 months post-operatively using the patient and observer scar assessment scale and the Manchester scar scale. Experts evaluated the scars after 6 months using a modified version of both scales. Results: On days 7 and 14, significantly larger areas of the wound surface were closed in the hyaluronan group compared to the control group (p < 0.05). After 1 month, significantly more crusted areas remained in the control group than in the hyaluronan group (p < 0.05). At the 6-month self-assessments, the hyaluronan group evaluated their scars as being significantly better compared to the control group. Conclusions: The topical application of hyaluronic acid in combination with polyurethane foam as a wound dressing after split skin removal accelerated the wound healing rate and positively influenced scar appearance after 6 months. Three-dimensional scanning is useful for evaluating and documenting the wound healing process.