Thiem, Daniel G. E.

Background: This cross-sectional study aims to compare a new and non-invasive approach using hyperspectral imaging (HSI) with the conventional modified Allen’s test (MAT) for the assessment of collateral perfusion prior to radial forearm free flap harvest in healthy adults. HSI of the right hand of 114 patients was recorded. Here, three recordings were carried out: (I) basic status (perfusion), (II) after occlusion of ulnar and radial artery (occlusion), and (III) after releasing the ulnar artery (reperfusion). At all recordings, tissue oxygenation/superficial perfusion (StO2 (0–100%); 0–1 mm depth), tissue haemoglobin index (THI (0–100)) and near infrared perfusion index/deep perfusion (NIR (0–100); 0–4 mm depth) were assessed. A modified Allen’s test (control) was conducted and compared with the HSI-results. Results: Statistically significant differences between perfusion (I) and artery occlusion (II) and between artery occlusion (II) and reperfusion (III) could be observed within the population with a non-pathological MAT (each <0.001). Significant correlations were observed for the difference between perfusion and reperfusion in THI and the height of the MAT (p < 0.05). Within the population with a MAT >8 s, an impairment in reperfusion was shown (each p < 0.05) and the difference between perfusion and reperfusion exhibited a strong correlation to the height of the MAT (each p < 0.01). Conclusions: The results indicate a reliable differentiation between perfusion and occlusion by HSI. Therefore, HSI could be a useful tool for verification of the correct performance of the MAT as well as to confirm the final diagnosis, as it provides an objective, reproducible method whose results strongly correlate with those obtained by MAT. What is more, it can be easily applied by non-medical personnel. Keywords: hyperspectral imaging, Allen’s test, radial forearm free flap, microvascular surgery, microsurgery, reconstructive surgery, perfusion monitoring, flap imaging

Antiresorptive Medikamente wie Bisphosphonate und der monoklonale Antikörper Denosumab sind wirksam in der Osteoporosetherapie und bei malignen Knochenerkrankungen (ossäre Metastasen, Multiples Myelom), können aber Antiresorptiva-assoziierte Kiefernekrosen (AR-ONJ) auslösen. Obwohl der genaue Mechanismus der AR-ONJ-Entstehung noch unklar ist, existieren zuverlässige Behandlungsstrategien zur ONJ-Vermeidung, da die Assoziation mit lokalen Infektionen bzw. bakteriellen Eintrittspforten klinisch und wissenschaftlich gesichert ist. Die steigende Zahl betroffener Patienten durch eine alternde Bevölkerung, eine Ausweitung der Indikation und steigende Anzahl an Verordnungen rechtfertigt sich aus dem gesamtskelettal überwiegenden Nutzen für die Allgemeinheit. Gleichsam stellt die AR-ONJ eine Herausforderung für den interdisziplinären Behandlerverbund aus Zahnmedizinern, Parodontologen, Mund-, Kiefer-, Gesichts- und Oralchirurgen einerseits und den ärztlichen AR-Verordnern andererseits dar. Nur durch interdisziplinär abgestimmte individuelle Behandlungsstrategien ist eine wirksame ONJ-Vermeidung sicherzustellen. Manuskripteingang: 02.11.2020, Annahme: 20.01.2021 Keywords: AR, AR-ONJ, individuelles Risiko, interdisziplinäre Zusammenarbeit, Prophylaxe und Prävention

Purpose: This study aimed to evaluate whether different surface modifications affect the dynamics of bone remodeling at the implant and the adjacent local bone. Materials and Methods: Seventy-two dental implants with different surfaces (smooth and rough control [smCtrl; rCtrl], smooth and rough + O₂-plasma spray [smPlas; rPlas], smooth and rough + nanocrystalline SiO₂-hydroxyapatite coating [ncSiO₂HA] + O₂-plasma spray [smNB-C; rNB-C]; each n = 12) were bilaterally inserted into the femora of 36 New Zealand white rabbits. Intravital fluorochrome labeling was performed to visualize the dynamics of bone formation. The objectives were quantification of bone-to-implant contact (BIC [%]) at 2 and 4 weeks and the dynamic bone formation (dbf [%]) at the implants' adjacent local bone within 1, 2, and 3 weeks. Results: After 2 weeks, BIC was significantly higher for both smNB-C (BIC: 59% ± 2% SEM) and rNB-C (BIC: 66% ± 3% SEM) compared with controls (BIC: 42% ± 1% SEM; P .005). After 4 weeks, BIC for rNB-C (65% ± 2%) was superior to all test groups (BIC: 39% ± 2% SEM; P = .012). Regarding dbf (%), neither within 1 (P = .88), 2 (P = .48), nor after 3 weeks (P = .36) did any differences occur among the groups, even in accordance to the implant level. Conclusion: Although distance osteogenesis seems crucial for the development of secondary stability, and thus, of osseointegration, it apparently is not affected by a bioactive ncSiO2HA surface coating. Changing the surfaces' release kinetics and composition may increase distance osteogenesis. Keywords: adjacent bone formation, distance osteogenesis, intravital labeling, ncSiO2HA-coating, secondary stability, surface modification