Gerda Komposch

Establishment of oral mucosa phenotype in vitro in correlation to epithelial anchorage.

Abstract Cell-matrix interactions and the ordered deposition of basement membrane (BM) components are of major importance for the maintenance of tissue homeostasis in complex epithelia. This aspect was studied in vitro in a coculture system designed as an oral mucosa model. As crucial epithelial features the kinetics of proliferation, expression of site-specific keratins as well as integrin patterns in correlation to synthesis of BM components were assessed by immunohistochemistry and in situ hybridization. Comparison with non-cornified gingiva as tissue of origin revealed different stages of epithelial development, eventually leading to complete reconstruction within a time frame of 1–3 weeks. First, the initial activated stage up to 1 week was characterized by (a) high keratinocyte proliferation, (b) extended expression of the basal cell-specific keratin K5 and (c) a patchy pattern of the differentiation-specific keratins K4 and K13. Second, after 2 weeks the improvement of histoarchitecture correlated to (a) predominant K5 expression in the basal and (b) extension of K4 and K13 within the suprabasal cell compartment, (c) high expression of integrins α3β1 and α6β4 including their ligand laminin-5 and (d) accumulating deposition of basement membrane components. Third, virtually complete tissue normalization at 3 weeks was indicated by (a) restriction of K5 to the basal cell area, (b) regular suprabasal localization of K4 and K13, (c) polarization of integrins to basal and parabasal cells and (d) linear codistribution of collagen IV, “classical” laminin (-1 or -10) and laminin-5 underneath the basal cells. Thus, these organotypic cocultures represent relevant equivalents for non-keratinized oral mucosa with typical gingival differentiation features and in addition suitable models for preclinical trials such as prospective dental material testing.

Mesiodentes: Inzidenz, morphologie, ätiologie

ZusammenfassungTrotz zahlreicher Veröffentlichungen über klinische, radiologische und chirurgische Aspekte in der Therapie von Mesiodentes bleibt die Frage nach der Ätiologie dieser Zähne weitgehend unbeantwortet. Ziel dieser Studie war daher, ursächliche Faktoren bei unseren Patienten mit Mesiodentes zu eruieren. Die Untersuchung beinhaltete 30 Patienten mit insgesamt 45 Mesiodentes. Bei 31% der Patienten lag eine familiäre Disposition vor, so daß der Vererbung eine maßgebliche Rolle bei der Entstehung von Mesiodentes zugemessen werden muß. Die Ergebnisse legen weiterhin die Vermutung nahe, daß ein ätiologischer Zusammenhang zwischen dem Auftreten von Mesiodentes und anderen Zahn- und Kieferanomalien wie Hyperdontie, Hypodontie und Spaltbildung besteht. Zuletzt sprechen sowohl die Gemination des Milchschneidezahnes auf der Seite des Mesiodens bei einem unserer Patienten als auch die mesiodistalen Breitenvergleiche der mittleren Schneidezähne dafür, daß der Theorie der Dichotomie des Zahnsäckchens bei der Entstehung von Mesiodentes den Vorzug gegenüber der Theorie einer Überaktivität der Zahnleiste gegeben werden muß.SummaryThere are many publications in the literature focusing on clinical, radiological and surgical aspects of the treatment of mesiodentes. However, the etiology of this dental anomaly remains widely unclear. The purpose of this study was to evaluate etiologic factors for mesiodentes in a collective comprising 30 patients with a total of 45 mesiodentes. Thirty-one percent of the patients showed a familial disposition, pointing to inheritance as a key factor in the development of mesiodentes. Our results further support the hypothesis of related etiologic factors for several dental and craniofacial anomalies, such as hyperdontia, hypodontia and cleft lip and palate. Finally, we report the gemination of a deciduous incisor on the same side as a mesiodens. We also found differences in the mesiodistal width of central incisors depending on unilateral or bilateral occurrence of mesiodentes. Both these findings support the dichotomy theory of the split in the tooth bud inducing the development of mesiodentes, a theory we favor over that of local hyperactivity of the dental lamina.

Dental Arch Widths and Mandibular-Maxillary Base Widths in Class II Malocclusions Between Early Mixed and Permanent Dentitions

The aim of the study was to analyze the transverse morphology and development of the dental arches and skeletal mandibular-maxillary bases in untreated Class II malocclusions. Using the records of the Belfast Growth Study, a Class II division 1 group (II/1) and a Class II division 2 group (II/2) were compared with a Class I group and a control group with good occlusion. On posteroanterior cephalograms, maxillary skeletal base width and bigonial and biantegonial widths were determined at two-year intervals between seven and 15 years. Maxillary and mandibular intermolar widths were measured on the associated study casts. As a result, maxillary skeletal base widths were smallest in the Class II/1 subjects. No statistically significant differences were found among the groups for the skeletal mandibular widths. With respect to the development of the dental arches, maxillary intermolar widths were smaller in the Class II/1 group than in the Class I and the good-occlusion groups. These group differences were present for the total period of observation, ie, seven to 15 years, and statistically significant at most ages. When the relative difference between the maxillary and the mandibular intermolar widths was examined, the Class II/1 cases were found to have the largest average difference (about -2.5 mm for boys and -1.5 mm for girls), indicating a relatively narrow maxillary arch. Less pronounced molar differences were found in the Class II/2 group. In the Class II/1 subjects the deviations in molar differences observed at 15 years of age were established already at 7 years of age and maintained during 7 and 15 years of age.

Assessment of acute cyto- and genotoxicity of corrosion eluates obtained from orthodontic materials using monolayer cultures of immortalized human gingival keratinocytes

Whilst a patient is undergoing orthodontic treatment, dental appliances based on non-precious metals or titanium remain in the oral cavity for up to several years. Throughout this period the appliance is in either direct or indirect contact with the oral mucosa.To investigate the possibility of cell damage occurring as a result of appliance corrosion, monolayer cultures of immortalized human gingival keratinocytes were assessed for acute cyto- and genotoxicity using the hexosaminidase assay and the Comet assay respectively. The materials tested included 1. a nickel-free wire, 2. a UK-1 bond, 3. nickel-free as well as nickel-containing brackets with and without color signature and 4. a titanium expansion screw. Each of the test materials was corroded in a solution consisting of equal amounts of lactic acid and sodium chloride (0.1 M) for 1, 3, 7 and 14 days. The cell cultures were then exposed to eluates exhibiting the highest ion concentrations.None of the eluates was found to exhibit acute cytotoxicity, regardless of the type of test system used. Qualitative assessment using neutral red dye for live cells and either trypan blue or propidium iodide to disclose dead cells failed to reveal any significant increase in cell damage when exposed cells were compared to control cultures. Unrestricted cell vitality was confirmed by quantifying viable cells through measurement of hexosaminidase enzyme activity. Furthermore, assessment of genotoxicity revealed no apparent DNA damage to immortalized gingival keratinocytes following exposure to the test eluates.Because the materials tested in this study were corroded using the exacting methods normally applied to precious metals or gold-containing alloys, the lack of either acute cyto- or genotoxic effects following exposure to the test eluates indicates that the materials tested exert no adverse effects on cells similar to those of the target tissue exposed to the materials in situ.ZusammenfassungDie während der kieferorthopädischen Behandlung eingesetzten Apparaturen, die aus Nichtedelmetallegierungen oder Titan bestehen, verbleiben häufig über Jahre in der Mundhöhle. Während des gesamten Zeitraums steht die Apparatur in direktem oder indirektem Kontakt mit der Oralmukosa.Um zu untersuchen, ob eine mögliche Zellschädigung durch Korrosion der Apparatur hervorgerufen wird, wurden Monolayerkulturen von immortalisierten humanen Gingivakeratinozyten mit dem Hexosaminidasetest und dem Comet-Assay (Einzelzellgelelektrophorese) auf akute Zyto- und Gentoxizität hin untersucht. Untersucht wurden 1. ein nickelfreier Draht, 2. ein UK-1-Band, 3. nickelfreie und nickelhaltige Brackets mit und ohne Farbmarkierung und 4. eine Dehnschraube aus Titan. Jedes der Untersuchungsmaterialien wurde für einen, drei, sieben und 14 Tage in einer Lösung, die zu gleichen Teilen aus Milchsäure und Natriumchlorid (0,1 M) bestand, korrodiert. Danach wurden die Zellkulturen mit den Eluaten, die die höchsten lonenkonzentrationen aufwiesen, inkubiert.Unabhängig vom Testsystem zeigte keines der Eluate eine akute Zytotoxizität. Die qualitative Untersuchung mit dem Farbstoff Neutralrot, der lebende Zellen färbt, und Trypanblau oder Propidiumjodid, die tote Zellen anfärben, ergab keinerlei Zunahme der Zellschädigung im Vergleich von exponierten zu nichtexponierten Kontrollkulturen. Die uneingeschränkte Zellvitalität wurde durch die Quantifizierung lebender Zellen mittels Messung der Aktivität des Enzyms Hexosaminidase bestätigt. Darüber hinaus ließ die Untersuchung der Gentoxizität nach Eluatexposition keine sichtbare DNA-Schädigung an immortalisierten Gingivakeratinozyten erkennen.Die in dieser Studie untersuchten Materialien wurden unter Bedingungen korrodiert, die normalerweise auf Edelmetalle oder goldhaltige Legierungen angewendet werden. Das Ausbleiben zyto- oder gentoxischer Effekte nach Eluatexposition zeigt, daß die getesteten Materialien keine schädigenden Effekte auf Zellen ausüben, die große Ähnlichkeit zu denen des Zielgewebes aufweisen, das den Materialien in situ ausgesetzt ist.

The HPV-16 E5 Protein Inhibits TRAIL- and FasL-Mediated Apoptosis in Human Keratinocyte Raft Cultures

By using raft cultures of the polyclonal HaCaT cell lines stably transfected either with E5 (HaCaT/E5) or the empty vector (HaCaT/pMSG) as reference, we investigated the effect of the human papillomavirus type 16 (HPV-16) E5 protein on apoptosis. In comparison to conventional monolayer cultures this model system allows analysis of apoptosis under more tissue-like conditions by mimicking the stratified organization of a normal surface epithelium. Apoptosis was triggered either by FasL or TRAIL. Execution of the death program was checked at early and late stages by monitoring procaspase-3 cleavage and DNA fragmentation, respectively. Rafts of E5-expressing keratinocytes were completely protected from apoptosis and showed a background of apoptotic cells as low as the untreated cultures. In contrast, the HaCaT/pMSG cultures revealed a dramatic increase in apoptotic cells upon ligand treatment throughout the epithelial compartment. We conclude that the presence of the HPV-16 E5 protein in our tissue-like model prevents FasL- or TRAIL-mediated apoptosis.

[The etiology of canine tooth impaction--a space analysis].

ZusammenfassungZiel dieser Untersuchung ist es festzustellen, inwieweit ein Platzüberschuß als ätiologischer Faktor für die Impaktierung der Oberkieferenckzähne, unter besonderer Berücksichtigung der Rolle der seitlichen Schneidezähne, in Betracht gezogen werden muß. Zur Klärung dieser Frage wurden sowohl die Anfangs- und Abschlußmodelle von 63 Patienten mit 84 impaktierten Eckzähnen als auch die Fernröntgenseitenbeilder von 116 Patienten mit 144 verlagerten Eckzähnen vermessen. Die Ergebnisse dieser Studie zeigen: Die palatinale Verlagerung Überwog mit 84,5% deutlich gegenüber der verstibulären Retention mit 15,5%. Ein Platzmangel konnte lediglich bei 18% deer Patienten mit palatinaler Verlagerung im Gegensatz zu 46% bei vestibulärer Impaktierung festgestellt werden. Hypoplastische seitliche Schneidezähne traten in 35% der Fälle mit palatinaler Verlagerung, edoch bei keinem Patienten mit vestibulärer Retentiion auf. Die kephalometrische Analyse zeigte ebenfalls einen unterschiedlichen Gesichtsschädelaufbau bei palatinaler und vestibulärer Verlagerung. Während 80% der Patienten mit palatinaler impaktierung einen horizontalen achstumtyp aufwiesen, wurde ein solcher nur in 23% der Fälle mit vestibulärer Retention gefunden.SummaryThe aim of this study was to examine to what extent excess space must be taken into consideration as an etiological factor in upper canine impaction with special attention paid to the role of the adjacent laterals. To clarify this question the pre- and post-treatment models of 63 patients with a total of 84 impacted cuspids were measured and the cephalograms of 116 patients havign 144 impacted cuspids were analyzed. The results of this study revealed: 85.5% of the cuspids were palataly impacted while 15.5% were labially impacted. An arch deficiency was found in only 18% of the palatally impacted cuspids, whereas there was an arch-length deficiency in 46% of the buccally impacted. In 35% of the cases there was a correlation between peg shaped laterals and palatal impaction, however, such was not present in te patients with vesbibular retention. Finally the cephalometric data revealed horizontal growth characteristics in 80% of the palatally impacted canines as opposed to 23% in those labially impacted.The aim of this study was to examine to what extent excess space must be taken into consideration as an etiological factor in upper canine impaction with special attention paid to the role of the adjacent laterals. To clarify this question the pre- and post-treatment models of 63 patients with a total of 84 impacted cuspids were measured and the cephalograms of 116 patients having 144 impacted cuspids were analyzed. The results of this study revealed: 84.5% of the cuspids were palatally impacted while 15.5% were labially impacted. An arch deficiency was found in only 18% of the palatally impacted cuspids, whereas there was an arch-length deficiency in 46% of the buccally impacted. In 35% of the cases there was a correlation between peg shaped laterals and palatal impaction, however, such was not present in the patients with vestibular retention. Finally the cephalometric data revealed horizontal growth characteristics in 80% of the palatally impacted canines as opposed to 23% in those labially impacted.

Occlusal status and prevalence of occlusal malocclusion traits among 9-year-old schoolchildren

The aim of this study was to provide detailed information concerning clinically relevant occlusal traits and the prevalence of occlusal anomalies in an orthodontically relevant period of dental development. Four hundred and ninety-four German schoolchildren (237 males and 257 females), median age 9 years, were orthodontically examined. Overjet and overbite were measured to the nearest 0.5 mm, and sagittal molar relationships were registered clinically to the nearest quarter unit. In addition, crossbites, scissor bites, and midline displacements were evaluated. Descriptive statistics was complemented by testing gender differences and differences between groups with Class I and Class II anomalies (Mann-Whitney U-test) as well as a statistical evaluation of differences between the three dental stages (Kruskal-Wallis test). Overjet exhibited an extreme range between -2 and 12 mm (median values 3-3.5 mm). An increased overjet was more prevalent than a reduced or reverse overjet, and a severely increased overjet greater than 6 mm was a common finding affecting around 5-10 per cent of the children. Similarly, overbite showed considerable variations of between -1 and 9 mm (medians 3-3.5 mm) and males exhibited a significantly larger overbite than females. In Class II malocclusion subjects, overbite was significantly enlarged (on average between 0.5 and 1 mm) when compared with those with a Class I malocclusion. Traumatic contact of the gingiva affected every 14th child. A Class II molar relationship of three-quarter units or more was a frequent finding affecting more than one child in five. In addition, at 9 years of age, 3 per cent of the children exhibited a Class III molar relationship of at least a half unit. The wide range of orthodontically relevant occlusal traits found in the present study underlines the need for orthodontic screening at 9 years of age (or earlier).

Modulation of the epidermal growth factor receptor by the human papillomavirus type 16 E5 protein in raft cultures of human keratinocytes.

It has been shown that the E5 protein of the human papillomavirus type 16 modulates epidermal growth factor receptor downregulation in monolayer cultures of human keratinocytes and mouse fibroblasts. We have now analysed the effect of this protein on the expression, the distribution and the activation of EGF receptors in raft cultures derived from an E5-transfected human keratinocyte cell line. The epithelia generated in these cultures were stratified and exhibited suprabasal expression of cytokeratins 1 and 10, which are known markers of early epidermal differentiation. In situ hybridization with an antisense riboprobe to the human papilloma virus type 16 E5 protein revealed a homogeneous gene expression within the entire epithelium of E5-transfected but not empty vector-transfected control cultures. Treatment of serum-starved rafts with EGF for 48 hours led to a strong decrease of suprabasal EGF receptors in control cultures, but not in rafts of E5-expressing cells. Under these conditions, no activated receptors were observed in control cultures, but activated receptors were still present in E5-raft cultures. Our results indicate that human papilloma virus type 16 E5-mediated modulation of EGF receptor expression occurs in a time- and structure-dependent manner in epithelial equivalents of human keratinocytes.

Connexin 43 expression is downregulated in raft cultures of human keratinocytes expressing the human papillomavirus type 16 E5 protein.

Abstract. A decrease in gap junction-mediated cell-to-cell communication has previously been observed in monolayer cultures of human keratinocytes (HaCaT cells) expressing the human papillomavirus type 16 E5 (HPV16 E5) gene and attributed to the reduced phosphorylation of connexin 43, the most abundant connexin in HaCaT cells. In line with this observation, we have now analyzed the effect of HPV16 E5 on connexin 43 expression in raft cultures produced by transfected HaCaT cells. These keratinocytes transcribe HPV16 E5 under the control of a dexamethasone-inducible promoter. Our results show that treatment with dexamethasone leads to an almost complete disappearance of connexin 43 in rafts expressing the E5 gene but not in control rafts. In our study we discuss the possible effects of this downregulation on cell-cell communication and cellular malignant transformation.

Sucking efficiency of early orthopaedic plate and teats in infants with cleft lip and palate

Intraoral negative pressure during bottle feeding with two kinds of teats (a regular Nuk and a cleft Nuk) was measured in 7 infants with cleft lip and palate, 8 infants with cleft palate, 2 infants with cleft lip, 4 infants with operated cleft lip and palate and 7 normal infants. Infants with cleft lip and palate or cleft palate were unable to generate negative pressure before cleft lip and palate closure. The presence or absence of an early orthopaedic plate did not make any difference. In infants with unoperated cleft lip and with operated cleft lip and palate, peak negative pressure during feeding differed little from that of normal infants.