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Background: Computerized virtual patients (VP) have spread into many areas of healthcare delivery and medical education. They provide various advantages like flexibility in pace and space of learning, a high degree of teaching reproducibility and a cost effectiveness. However, the educational benefit of VP as an additive or also as an alternative to traditional teaching formats remains unclear. Moreover, there are no randomized-controlled studies that investigated the use of VP in a dental curriculum. Therefore, this study investigates VP as an alternative to lecturer-led small-group teaching in a curricular, randomized and controlled setting.
Methods: Randomized and controlled cohort study. Four VP cases were created according to previously published design principles and compared with lecturer-led small group teaching (SGT) within the Oral and Maxillofacial Surgery clerkship for dental students at the Department for Cranio-, Oral and Maxillofacial Plastic Surgery, Goethe University, Frankfurt, Germany. Clinical competence was measured prior (T0), directly (T1) and 6 weeks (T2) after the intervention using theoretical tests and a self-assessment questionnaire. Furthermore, VP design was evaluated using a validated toolkit.
Results: Fifty-seven students (VP = 32; SGT = 25) agreed to participate in the study. No competence differences were found at T0 (p = 0.56). The VP group outperformed (p < .0001) the SGT group at T1. At T2 there was no difference between both groups (p = 0.55). Both interventions led to a significant growth in self-assessed competence. The VP group felt better prepared to diagnose and treat real patients and regarded VP cases as a rewarding learning experience.
Conclusions: VP cases are an effective alternative to lecture-led SGT in terms of learning efficacy in the short and long-term as well as self-assessed competence growth and student satisfaction. Furthermore, integrating VP cases within a curricular Oral and Maxillofacial Surgery Clerkship is feasible and leads to substantial growth of clinical competence in undergraduate dental students.
Mastectomy in female-to-male transgender patients: A single-center 24-year retrospective analysis
(2019)
Background: Mastectomy in male transgender patients is an important (and often the first) step toward physical manhood. At our department, mastectomies in transgender patients have been performed for several decades.
Methods: Recorded data were collected and analyzed for all male transgender patients undergoing mastectomy over a period of 24 years at our department.
Results: In total, 268 gender-reassigning mastectomies were performed. Several different mastectomy techniques (areolar incision, n=172; sub-mammary incision, n=96) were used according to patients’ habitus and breast features. Corresponding to algorithms presented in the current literature, certain breast qualities were matched with a particular mastectomy technique. Overall, small breasts with marginal ptosis and good skin elasticity allowed small areolar incisions as a method of access for glandular removal. In contrast, large breasts and those with heavy ptosis or poor skin elasticity often required larger incisions for breast amputation. The secondary correction rate (38%) was high for gender reassignment mastectomy, as is also reflected by data in the current literature. Secondary correction frequently involved revision of chest wall recontouring, suggesting inadequate removal of the mammary tissue, as well as scar revision, which may reflect intense traction during wound healing (36%). Secondary corrections were performed more often after using small areolar incision techniques (48%) than after using large sub-mammary incisions (21%).
Conclusions: Choosing the suitable mastectomy technique for each patient requires careful individual evaluation of breast features such as size, degree of ptosis, and skin elasticity in order to maximize patient satisfaction and minimize secondary revisions.
Background: Due to their increased precision, CAD/CAM generated bars (Computer-Aided Design/ Computer-Aided Manufacturing) are increasingly utilized in implant prosthodontics. For optimal clinical results, surface morphology should promote the integration of soft tissue while minimizing plaque and bacterial retention.
Objective: Despite their clinical use, only limited information on the biological and clinical surface quality of CAD/CAM milled bars is available. The aim of the study was therefore to characterize the surface topography of bars of different manufacturers based on the profilometric analysis and the need for manual post-processing in the laboratory.
Methods: A custom mandibular edentulous cast with four anterior implants was used as a reference cast and reproduced eight times. On each reproduction cast, corresponding scan flags were positioned and digitized. Acrylic 3D printed bar frameworks were produced and sent to the respective production center along with the digital files of the CAD bars for milling. In the course of profilometric analysis, all bars were examined in three critical Regions of Interest (ROI): Transmucosal, labial, basal. Sa and Ra values of each construction were determined. To evaluate the necessary refinishing time eight dental technicians macroscopically evaluated the bars by performing a subjective visual inspection. Kruskal-Wallis H-tests and Tukey and Kramer's post hoc tests were applied to detect differences between the samples.
Results: After profilometric examination, three specimens (Dentsply Sirona: ZDC; Straumann: ZST; CAMLOG: ZCC) demonstrated surface roughness values in the biological acceptable range (Sa 0.2-0.4 μm) in the transmucosal region and provided optimal conditions for a reliable soft tissue adaptation. The Ra measurements revealed values beyond the acceptable threshold in the transmucosal region for three bars (Straumann: ZST; Dentsply Sirona: ZDC; Amann Girrbach: LAC). Four bars (LAC: Amann Girrbach; ZBC: BEGO; Datron: LDC & LDT; Zirkonzahn: ZZC) needed undesirable extensive manual rework. The evaluation of quality and time for manual post-processing by dental technicians confirmed the measurement-based ranking of the bars.
Conclusion: It is desirable to define a clear roughness threshold for the clinical acceptance of transmucosal CAD/CAM generated surfaces. Clinical studies with profilometric data could help to further improve the surface quality of CAD/CAM milled bars and reduce the need for manual reworking time and effort.
Different tissue engineering techniques are used to support rapid vascularisation. A novel technique is the use of platelet-rich fibrin (PRF), an autologous source of growth factors. This study was the first to investigate the influence of PRF matrices, isolated following different centrifugation protocols, on human dermal vascular endothelial cells (ECs) in mono-culture and co-culture with human primary fibroblasts (HFs) as an in vitro model for tissue regeneration. Focus was placed on vascular structure formation and growth factor release. HFs and ECs were cultivated with PRF prepared using a high (710 ×g) or low (44 ×g) relative centrifugation force (RCF) over 14 d. Immunofluorescence staining and immunohistochemistry were used to evaluate the microvascular formation. Cell culture supernatants were collected for evaluation of growth factor release. The results showed a PRF-mediated effect on the induction of angiogenesis in ECs. Microvessel-like structure formation was promoted when ECs were combined with low-RCF PRF as compared to high-RCF PRF or control group. The percentage of vascular lumen area was significantly higher in low-RCF PRF, especially at day 7, which coincided with statistically significantly higher growth factor [vascular endothelial factor (VEGF), transforming growth factor β1 (TGF-β1) and platelet derived growth factor (PDGF)] concentration measured in low-RCF PRF as compared to high-RCF PRF or control group. In conclusion, reducing the RCF according to the low-speed centrifugation concept (LSCC) resulted in increased growth factor release and angiogenic structure formation with EC mono-culture, suggesting that PRF may be a highly beneficial therapeutic tool for tissue engineering applications.
Platelet-rich fibrin (PRF) is a blood concentrate derived from venous blood that is processed without anticoagulants by a one-step centrifugation process. This three-dimensional scaffold contains inflammatory cells and plasma proteins entrapped in a fibrin matrix. Liquid-PRF was developed based on the previously described low-speed centrifuge concept (LSCC), which allowed the introduction of a liquid-PRF formulation of fibrinogen and thrombin prior to its conversion to fibrin. Liquid-PRF was introduced to meet the clinical demand for combination with biomaterials in a clinically applicable and easy-to-use way. The aim of the present study was to evaluate, ex vivo, the interaction of the liquid-PRF constituents with five different collagen biomaterials by histological analyses. The results first demonstrated that large variability existed between the biomaterials investigated. Liquid-PRF was able to completely invade Mucograft® (MG; Geistlich Biomaterials, Wolhusen, Switzerland) and to partly invade Bio-Gide® (BG; Geistlich Biomaterials, Wolhusen, Switzerland) and Mucoderm® (MD; Botiss Biomaterials, Berlin, Germany), and Collprotect® (CP; Botiss Biomaterials, Berlin, Germany) showed only a superficial interaction. The BEGO® collagen membrane (BCM; BEGO Implant Systems) appeared to be completely free of liquid-PRF. These results were confirmed by the different cellular penetration and liquid-PRF absorption coefficient (PAC) values of the evaluated membranes. The present study demonstrates a system for loading biomaterials with a complex autologous cell system (liquid-PRF) in a relatively short period of time and in a clinically relevant manner. The combination of biomaterials with liquid-PRF may be clinically utilized to enhance the bioactivity of collagen-based biomaterials and may act as a biomaterial-based growth factor delivery system.
After removal of a dental implant or extraction of a tooth in the upper jaw, the closure of an oroantral fistula (OAF) or oroantral communication (OAC) can be a difficult problem confronting the dentist and surgeon working in the oral and maxillofacial region. Oroantral communication (OAC) acts as a pathological pathway for bacteria and can cause infection of the antrum, which further obstructs the healing process as it is an unnatural communication between the oral cavity and the maxillary sinus. There are different ways to perform the surgical closure of the OAC. The decision-making in closure of oroantral communication and fistula is influenced by many factors. Consequently, it requires a combination of knowledge, experience, and information gathering. Previous narrative research has focused on assessments and comparisons of various surgical techniques for the closure of OAC/OAF. Thus, the decision-making process has not yet been described comprehensively.
The present study aims to illustrate all the factors that have to be considered in the management of OACs and OAFs that determine optimal treatment.