Okklusion,Kiefergelenke und kieferorthopädische Behandlung

Zusammenfassung Für die Okklusion und den Gelenkbereich sind Zuordnungsnormen existent. Dies ist im Seitenzahnbereich die Höcker-Fossa-Relation, im Frontzahnbereich die Zuordnung der Unterkiefer-Inzisalkanten zu der Nullpunktlinie der palatinalen Konkavitäten im Oberkiefer und im Gelenkbereich die physiologische Kondylenposition. Letztere läßt sich im Pantogramm durch den Wendepunkt der von der Achse bei sagittaler Grenzführung gezeichneten Kurve präzisieren, in Übertragung aber auch im Röntgenbild ermitteln.Ziel der kieferorthopädischen Behandlung sollte die physiologische Zuordnung von Seitenzähnen, Frontzähnen und Gelenken sein. Das vorgestellte Funktionsmodell gibt Hilfestellungen bei der Behandlung auf ein funktionelles Optimum hin.Die Gelenke sind bei der Behandlung wie ein eigenes terminales Okklusionspaar zu betrachten. Ihre korrekte Einstellung läßt sich bisher nur durch Röntgenbilder und durch die pantographische Aufzeichnung darstellen.

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Summary We are convinced that there is a relation between the occlusion and the temporomandibular joint. In the molar region the correlation is known as the cusp-fossa relationship. In the incisor region the corresponding structures are the mandibular incisor tips and the palatal concavities of the upper incisors. We have designated the correlation in the TMJ-region as the physiological condyle position, which can be identified in the sagittal pantogram by the turning point of the traced sigmoid curve. Similarly this position can be shown by our method on the TMJ-radiograph.The aim of orthodontic treatment should be a physiological positioning of molars, incisors and joints. The functional model presented above can render assistance in achieving a functional optimum in treatment.The temporomandibular joints must be regarded in treatment as additional occluding points. Up to now their correct positioning has been visible only through the use of TMJ-radiographs and pantographic tracings.

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Résumé Il existe des normes structurelles correspondantes entre l'occlusion et l'articulation temporomandibulaire; à savoir dans les zones latérales d'arcades la relation cuspide-sillon, dans le segment antérieur l'arête des incisives inférieures glissant le long des faces palatines des incisives supérieures jusqu'à la ligne d'arrêt et au niveau de l'articulation la position physiologique du condyle. Cette corrélation s'établit dans le plan sagittal du pantogramme par l'existence d'un point tournant du tracé sigmoïde; on peut transposer cette position dans l'image radiographique.Le but d'un traitement orthodontique est de coordonner physiologiquement les segments latéraux et antérieur d'arcades et l'articulation temporo-mandibulaire. Des moulages fonctionnels préétablis nous aident à obtenir la meilleure fonction au cours du traitement.On doit considérer la double articulation temporo-mandibulaire comme une occlusion finale. Seuls la radiologie et les tracés pantographiques permettent de juger de la position correcte des condyles dans leurs fosses glénoïdes.

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In memoriam Herrn Prof. Dr.G. Müller von seinen ehemaligen Schülern und Mitarbeitern.     

Motor control of jaw muscles in chewing and in isometric biting with graded narrowing of jaw gape

When a certain bite force is applied during unilateral chewing, the combination of jaw elevator muscle activities is different than when a comparable force is applied in unilateral isometric biting, e.g. on a force transducer. Masticatory peak force is generated in a nearly isometric phase of the chewing cycle, with a jaw gape of about 1 mm. In contrast, peak force in isometric biting on force measuring equipment usually induces jaw gapes of 6 mm or even more. Therefore, we tested the hypothesis that the jaw gape influences relative activation of elevator muscles in unilateral isometric biting. We further examined whether such influence could explain the different activity combinations of chewing and isometric biting. In thirty asymptomatic males, masseter and temporalis activities were recorded during intermittent isometric biting with jaw gapes of 6, 5, 3, 2 and 1 mm and during unilateral chewing. Activity combinations were described by working/balancing ratios and by temporalis/masseter ratios. With decreasing jaw gape the working/balancing ratio of the posterior temporalis decreased (P < 0.002) while that of the masseter increased (P < 0.001). Likewise, the temporalis/masseter ratio on the balancing side increased (P < 0.001). With decreasing jaw gape, activity ratios of isometric biting approached ratios of chewing. We conclude that: (i) relative jaw muscle activation in isometric biting depends on the jaw gape, (ii) relative muscle activation in chewing resembles relative activation of isometric biting with a small 'chewing-like' gape. This suggests that characteristic activity combinations in chewing are mainly a result of the approximately isometric contraction during the slow closing phase of the chewing cycle.     

Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: a microscopical and immunohistochemical study in the sheep

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft+Bio-Gide (experiment 2), and bone graft+Bio-Oss/Bio-Gide (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.     

Characterization of porosity of isostatically pressed and sintered nickel-base powdered metal.

Characterization of the pore structure of compacted and sintered parts made from a nickel-base powder was accomplished using the mercury porosimetry method. The theoretical density values for the sintered specimens varied from 56.3 to 96.7% which corresponds to a porosity of 43.7 to 3.3%. A maximum interconnecting median pore diameter of 21 mum resulted from a -80/+200 mesh powder compacted at 138 MN/m2 and sintered for 2 h at 1250 degrees C. Photomicrographs of the same sample showed that it had a maximum pore diameter of 200 mum. The interconnected pore volume decreased with decreasing particle size of the powder, increasing compaction pressure, and increasing sintering temperature. Mechanical properties of tensile strength, yield strength, elastic modulus and percentage elongation were correlated with the pore structure. Proper selection of particle size, compaction pressure, sintering times and sintering temperatures should permit parts with controlled porosity characteristics to be produced that possess adequate mechanical properties for application as implants.     

Tetracycline inhibits Porphyromonas gingivalis lipopolysaccharide-induced lesions in vivo and TNFα processing in vitro

Lipopolysaccharides (LPS) are considered one of the more important virulence factors related to the pathogenesis of periodontal diseases. Based on tetracycline (TTC) ability to bind divalent metal ions, the present study was designed to examine the effect of TTC on P. gingivalis LPS-induced lesions in vivo and on LPS-induced TNFα production in vitro . Subcutaneous injection of 50-100 μg of P. gingivalis LPS into BALB/C mice induced a visible lesion within 24 h with evident tissue necrosis. Daily systemic administration of TTC for the first 4 d following LPS challenge reduced the size of the lesion, and total inhibition of lesion formation was observed in 75-100% of the treated mice. A non-related broad spectrum antibiotic, ampicillin, or the IL-1 inhibitor ML-20, had no effect on the lesion size. In order to explore some aspects of the mechanism involved, we tested the effect of TTC on LPS-induced TNFα secretion by human monocytes in vitro . TTC (1 mM) was found to block LPS-stimulated TNFα secretion. Western blotting of monocyte cytoplasmic membranes for membrane-bound TNFα show that TTC causes the retention of membrane-associated TNFα on monocyte membranes, thereby preventing the release of TNFα into the culture media. The results suggest the TTC is an effective in vivo therapy for preventing P. gingivalis LPS-induced subcutaneous lesion formation in the murine model. The mechanism of TTC treatment probably involves blocking the activity of metal] oprotemases. including TNFY processing enzyme, thereby preventing LPS-induced tissue destruction.     

Characterization of verruciform xanthoma by in situ hybridization and immunohistochemistry

Verruciform xanthoma (VX) is a rare, benign lesion, mainly found in the oral mucosa. Histologically and ultrastructurally. the lesion is characteristic and well defined. However, the etiology of the lesion remains unclear. The purpose of the present study was to elaborate upon the pathogenesis of VX by evaluation of an additional series of oral examples for human papillomaviruses (HPV). using immunohistochemistry and in situ hybridization, and to further characterize the cellular components of VX immunohistochemically. Twelve specimens diagnosed as VX were retrospectively collected. One of the twelve specimens was positive for HPV types 6/11 by in situ hybridization. None of the twelve specimens demonstrated the presence of HPV antigen by immunohistochemistry. By immunohis-tochemical studies, the predominant cells in the inflammatory infiltrate were T cells. The foam cells were of monocyte/macrophage lineage. S-100-positive (Langerhans) cells were occasionally found in the suprabasal layer of the epithelium. HLA-DR-positive keratinocytes were noted at the intense inflammatory sites. Taken together, these findings suggest that an immune response may play a role, at leas! in part, in VX pathogenesis.     

The effect of periodontal treatment on glycemic control in patients with type 2 diabetes mellitus

BACKGROUND, AIMS: This study was designed to explore the effect of periodontal therapy on glycemic control in persons with type 2 diabetes mellitus (DM). METHODS: 36 patients with type 2 DM (treatment group) received therapy for adult periodontitis during an 18-month period. A 36-person control group was randomly selected from the same population of persons with type 2 DM who did not receive periodontal treatment. RESULTS: These groups were well matched for most of the parameters investigated. During the nine-month observation period, there was a 6.7% improvement in glycemic control in the control group when compared to a 17.1% improvement in the treatment group, a statistically significant difference. Several parameters that could confound or moderate this glycemic control were explored. These included the treatment of non-dental infections, weight and medication changes. No moderating effect was associated with any of these variables. However, there were too few subjects in the study to have the statistical power necessary to assess these possible moderators of glycemic control. CONCLUSIONS: We interpret the data in the study to suggest that periodontal therapy was associated with improved glycemic control in persons with type 2 DM.