"Flipped OR": a modified didactical concept for a surgical clerkship in Oral and Maxillofacial Surgery.

The concept of the clerkship at the Department of Oral and Maxillofacial Surgery was modified into a modern and sustainable teaching model with a flipped classroom approach. The aim was to prove whether these changes increased the students' learning success. For the preparation of the clerkship, an e-learning module with 10 chapters was established. Students were supposed to access one chapter ahead of each day's seminar. A test to assess the gain in knowledge was undertaken before and after participation in the clerkship. An evaluation took place after the test. The results of the test after the clerkship were significantly higher than before (p<0.0001). The evaluation showed that the students were highly satisfied with the course in general, and the e-learning module specifically. In particular, the surgical videos helped them to better understand the operative steps. The clerkship at the Department of Oral and Maxillofacial Surgery was modified into a sustainable blended learning concept with a flipped classroom approach. With these developments, the "flipped operating room" was shown to be effective in improving knowledge and competence among undergraduate dental students.

Compensating for poor primary implant stability in different bone densities by varying implant geometry: a laboratory study.

The aim of this study was to determine the influence of implant diameter and length on primary stability in artificial bone blocks. In total, 240 implants of various diameters (Ø 3.3, 4.1, and 4.8mm) and lengths (8 and 12 mm) were inserted in four artificial bone blocks of different densities (D1-D4). The primary stability for each bone block density was measured and compared with the primary stability of a narrow and short implant (Ø 3.3mm, length 8mm) in the next higher density block. Analysis was done by three-way ANOVA, and mean differences were determined with the 95% confidence interval. Levels of primary stability achieved by choosing the next higher diameter or length were not comparable to those of the next level of block density. However, equivalent values could be achieved by selecting the largest diameter for short and long implants in the lowest block density D4, as well as for long implants in bone type D2. The diameter of an implant has greater influence on primary stability than length. In particular, in the case of poor bone quality, a variation of implant geometry can lead to significant improvement in primary stability.

Margins of oral leukoplakia: autofluorescence and histopathology.

Autofluorescence devices are widely used to examine oral lesions. The aim of this study was to see whether there were any signs of dysplasia, parakeratosis, or mucosal inflammation in the borders of homogeneous oral leukoplakia using autofluorescence, and we also compared clinically visible extensions with those detected by autofluorescence. Twenty patients with 26 homogeneous areas of oral leukoplakia were included in the study. After the clinically visible extensions of the lesion had been marked, we took a photograph through the autofluorescence device, which showed both borders in one picture. We then used photo-editing software to measure the size of the area of leukoplakia together with the area with loss of autofluorescence. We took 3 punch biopsy specimens: one from the leukoplakia, one 2.5mm from its marked borders, and one from healthy mucosa. Seventy-eight biopsy specimens were examined by an experienced pathologist, and 95% CI calculated to assess the amount of parakeratosis. Spearman's rank correlation was used to assess the association with mucosal inflammation. Ten areas of leukoplakia were surrounded by normal green autofluorescence, and 16 were consistent with loss of autofluorescence with a mean size of 66%, which exceeded the clinically visible size of the area of leukoplakia. We calculated that there was a strong association between these entities and their surrounding areas, with loss of autofluorescence for parakeratosis. Some leukoplakias showed clinically invisible extensions during histopathological examination and autofluorescence. The technique described enables clinicians to measure the extent of these lesions beyond their visible margins. We found no dysplasia, which emphasises that autofluorescence detects non-dysplastic lesions caused by mucosal inflammation and parakeratosis.