[Is the preoperative removal of dentures reasonable in every case?]. / Muss die Zahnprothese wirklich vor jeder Anästhesie entfernt werden?

Traditionally, dentures are removed prior to anaesthesia. Modern techniques in dentistry and the widespread use of regional anaesthesia should lead to a more individual approach to this problem. From a legal standpoint, the information about advantages and disadvantages concerning the removal of dentures can be explained without problems to the patient without medical background.

[Perioperative antibiotic prophylaxis in orthodontic bone operations of the facial skull]. / Perioperative Antibiotikaprophylaxe bei skelettverlagernden Operationen des Gesichtsschädels.

Intraoral orthognathic surgical procedures are clean-contaminated operations because of the facultative pathogenic flora of the oral cavity. Without antibiotic prophylaxis in this kind of operation a postoperative wound infection can be expected in 20-31% of cases. Therefore, a retrospective analysis of the clinical course of 545 patients with various dentofacial deformities was performed to evaluate the importance of perioperative antibiotic prophylaxis. The total rate of wound infections was 2.8% and lower than rates published in other comparable studies without antibiotic prophylaxis. The rate of wound infection after single mandibular osteotomy (4.1%) was significantly higher than the analogous amount after single maxillary osteotomy (0.8%) because of the mechanical strain of the surgical wound in the region of the mandibular angle and because of the high retention of food particles and other decay products in this area. The recognized rise in the wound infection rate by increasing the length of operation demonstrates that the extent of bacterial contamination of the surgical wound depends on the dimension and duration of surgery. Bacterial flora caused the noticed wound infections in 61.5% of cases aerobic-anaerobic mixed infections, which is in accordance with the results of similar publications. With increasing length of antibiotic prophylaxis, an increase in the incidence of antibiotic-associated side effects and in the wound infection rate could be observed. Therefore, an antibiotic prophylaxis which exceeds 3 days does not seem to be useful. In this study, in which cephalosporins were mostly used, the total rate of antibiotic-associated side effects (4.6%) was lower than analogous amounts of other groups of antibiotics. The analysis demonstrates that a short-term prophylaxis with broad-spectrum cephalosporins such as cefatoxime of 48 h is very effective and useful.

Atypical spontaneous factor VIII inhibitor: specific diagnostics and therapy of acute bleeding.

Differentiation of rapidly binding coagulation factor inhibitors from antiphospholipid antibodies is a challenge for the hemostaseologic laboratory, especially with respect to the different therapeutic consequences. Several immunological and functional assays for the diagnosis of these disorders have been proposed. Here we report the clinical and laboratory findings of a 65-year-old man who developed severe bleeding after a tooth extraction. The process leading to the diagnosis of a spontaneous atypical factor VIII inhibitor and the value of different laboratory tests are discussed.

[Osteosynthesis after sagittal division of the mandible. Biomechanical stability of various methods in a pig mandibular model]. / Osteosynthese nach sagittaler Spaltung des Unterkiefers. Biomechanische Festigkeiten verschiedener Verfahren in einem Schweinekiefermodell.

Forty years after the introduction of sagittal split osteotomy for transposition of the mandible according to Obwegeser, very different procedures for osteosynthesis are still discussed and practised. In a simple biomechanical model in the porcine mandible, five different methods for osteosynthesis using metallic screws (titanium, cobalt-chromium-molybdenum alloy) and one using a polymer screw (polylactic acid-copolymer blend), as well as the use of miniplates, were studied with regard to the stability of the compound. The Kruskal-Wallis H-test (variance analysis by ranks) showed statistically highly significant differences (P = 0.00017) regarding maximum stability. Osteosynthesis by miniplates was very stable with regard to the maximum load (Fmax = 234 N +/- 47), but not so in terms of three-dimensional stability of the osteosynthesis itself. The highest stability of osteosynthesis with screws only (Fmax = 183 N +/- 65) was found for a 2.7-mm titanium screw in triangular geometry. The use of 2.7-mm cobalt-chromium-molybdenum screws (Fmax = 173 N +/- 42) and 3.5-mm titanium screws (Fmax = 160 N +/- 76) did not make an statistical difference (P = 0.37). The mechanical values of 2.0-mm titanium screws in linear (Fmax = 113 N +/- 37) or triangular (Fmax = 136 N +/- 62) geometry and of 3.5-mm polylactic acid-copolymer blend screws (Fmax = 121 N +/- 33) did not differ statistically from each other (P = 0.75) but they did from the previous group (P = 0.019). In consideration of the low biting forces following sagittal split osteotomy, all tested procedures of osteosynthesis meet the mechanical requirements for clinical practice.

[Rhinoplasty using the coronal approach after extensive facial skull fractures]. / Nasenplastik über den koronaren Zugang nach ausgedehnten Gesichtsschädelfrakturen.

Functional, aesthetically perfect restoration of the face of patients suffering from a severely smashed facial skeleton requires exact centrifugal repositioning and miniplate osteosynthesis of all bony fragments. Nevertheless, the original height and form of the nose will not be restored with these means in some cases. Therefore, in 23 cases with shattered noses out of 487 midface-trauma patients in the years 1990-1995 the noses were onlay-grafted as the primary procedure in 9 cases via the coronal approach and as the secondary one when the metal plates were removed in 10 cases. A combination of primary and secondary procedures was done in 4 cases. Five times autogenous bone from outer calvarium was used and 22 times allogenic, conserved bone from organ donors (AAA bone). According to extent of the damage, mini-screws and/or mini-plates served to fixate the graft. In addition to the group of 13 patients in the years 1990-1993 with nasal bone grafts via the coronary approach, another group the same size with the same amount of trauma but without rhinoplasty was defined and compared to the first group. An aesthetic analysis was done by grading the results according to simple criteria from 0 to 6 points by the patient and by the examiner. Noses grafted via the coronary approach were evaluated as being significantly (P = 0.004, t-test for independent samples, SPSS) better (2.1 points on average +/- 1.1 SD) than conventionally treated noses (3.5 points on average +/- 0.8 SD).

[Comparative studies with apicoectomy using various surgical techniques and filling materials]. / Vergleichende Untersuchungen zur Wurzelspitzenresektion mit unterschiedlichen Operationstechniken und Füllungsmaterialien.

Follow-up examinations were made retrospectively on 799 apicoectomized teeth from a group of patients with a total of 3,524 apicectomies, the mean postoperative interval of observation being 4.2 years. An intraoperatively orthograde root-canal filling was performed in 51.3%, an intraoperatively retrograde in 23.7% and a preoperative filling in 25.0% of the patients. Apart from 126 teeth that had already been extracted, a further 160 teeth had been clinically and/or radiologically conspicuous, so that a total of 286 failures was to be recorded. The dentally related success graphs computed according to Kaplan and Meier (1958) showed a significantly worse success probability for the preoperative filling compared to the two other techniques. With regard to the different materials employed in orthograde application, the silver filling had a higher and the guttapercha filling a less favourable success quota compared to a titanium filling. Moreover, in the retrograde method, amalgam resulted in a significantly higher success probability than glass ionomer cement. With an attendant cyst there was a significantly improved success quota over apical parodontitis or a renewed operation. With regard to the localization of apicectomies, maxillary front teeth attained the highest success rate. The present results point unequivocally to an unfavourable outcome after preoperative endodontics and underscore the good prognosis of an intraoperatively orthograde filling. Due to the fact that biocompatibility is in the forefront today, time-tested materials, such as silver and amalgam, are clearly being used less.

[Temporomandibular joint reconstruction with free rib and iliac crest bone transplants]. / Die Problematik der Kiefergelenkrekonstruktion mit freien Knochentransplantaten von der Rippe und vom Beckenkamm.

From 1981-1992 we reconstructed the temporomandibular joint in 42 patients. In 33 cases reconstruction followed tumour resection of the mandible, almost advanced squamous cell carcinomas of the retromolar region. Primary reconstruction was made by an alloplastic condylar prosthesis combined with a plate for mandibular reconstruction. 2 years after first treatment secondary reconstruction followed by transplantation of a free iliac bone graft. In some cases a new condylus was formed using autogenous rib graft or allogenous cartilage. Result was adequate and painless oral aperture. For reconstruction after ankylosis, arthrosis or arthritis we use a autogenous costochondral graft. 9 patients received such treatment. In 5 or 9 cases with severe ankylosis we prefer a two-time-approach: after resection of the ankylosis we first fix an alloplastic implant (Palacos) at the skull base for distraction of the scar. Two or three years later we do secondary reconstruction with a costochondral graft. The final result strongly depends on functional postoperative treatment and the compliance of the patient.

Poly(L-lactide): a long-term degradation study in vivo. I. Biological results.

Three poly(L-lactides) with different molecular weights were synthesized. Small blocks (3 x 3 x 2 mm) and rods (25 x 3 x 2 mm) were produced either by injection moulding (amorphous parts, Mvis 200,000 and 120,000, respectively) or machined out of a solid aspolymerized polylactide block (crystalline parts, Mvis 429,000) and implanted into the dorsal muscle of rats. After 1 to 116 wk the rats were killed and the implants were recovered. Histological preparation was carried out using the cutting-grinding technique. All three polylactides had incorporated well, forming a collagenous fibrous layer. Crystalline block polylactide remained stable in form and structure over the whole observation period. Amorphous injection-moulded specimens developed a rough surface within weeks, then deep resorptive lacunae after ca. 1 yr and became totally degraded (Mvis 120,000) or nearly totally degraded (Mvis 200,000) after 2 yr. This velocity of biodegradation seems to meet the requirements for an absorbable material for osteosynthesis. Long-term implantation into rodents brings the problem of foreign-body tumorigenesis independent of the chemical nature of implants (the Oppenheimer effect). Observations in this study and in the literature are discussed.