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Biomedical subjects

G Komposch

Publications and source records attributed to G Komposch.

At least 37 records · Page 2Linked to original sources

A neural network approach to the analysis and classification of human craniofacial growth.

Planning of treatment in the field of orthodontics and maxillo-facial surgery is largely dependent on the individual growth of a patient. In the present work, the growth of 43 orthodontically untreated children was analysed by means of lateral cephalograms taken at the ages of 7 and 15. For the description of craniofacial skeletal changes, the concept of tensor analysis and related methods have been applied. Thus the geometric and analytical shortcomings of conventional cephalometric methods have been avoided. Through the use of an artificial neural network, namely self-organizing neural maps, the resultant growth data were classified and the relationships of the various growth patterns were monitored. As a result of self-organization, the 43 children were topologically ordered on the emerging map according to their craniofacial size and shape changes during growth. As a new patient can be allocated on the map, this type of network provides a frame of reference for classifying and analysing previously unknown cases with respect to their growth pattern. If landmarks are used for the determination of growth, the morphometric methods applied as well as the subsequent visualization of the growth data by means of neural networks can be employed for the analysis and classification of growth-related skeletal changes in general.

Adolescent↗

Mesiodentes: incidence, morphology, etiology.

There 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.

Craniofacial Abnormalities↗

Osteoblast-like properties of human periodontal ligament cells: an in vitro analysis.

Identifying the biological properties of the cells residing within the periodontal ligament (PDL) will help in understanding the role that these cells play in the various functions of the periodontal ligament, and will improve the success of clinical procedures such as orthodontic tooth movement. For this purpose, fibroblasts isolated from human periodontium were cultured and characterized both histochemically and biochemically with respect to their putative osteoblast-like properties. Histochemically, cultured PDL fibroblasts showed an intense staining for alkaline phosphatase (ALP). Biochemically, the basal ALP activity increased in culture over time. ALP levels after stimulation with 1 alpha, 25-dihydroxyvitamin D3 were significantly higher than those of control cultures. Moreover, immunofluorescence against osteocalcin (a highly reliable osteoblastic marker) was strongly positive. Von Kossa staining of the cell cultures revealed the formation of mineral-like nodules. These results indicate that human PDL fibroblasts exhibit in vitro phenotypic characteristics consistent with osteoblast-like cells, thus suggesting that such cells have the potential to differentiate into osteoblasts and/or cementoblasts.

Alkaline Phosphatase↗

Histomorphological and biochemical differentiation capacity in organotypic co-cultures of primary gingival cells.

To establish a three-dimensional in vitro test system mimicking the physiological situation of the oral cavity, organotypic co-cultures consisting of primary gingival cells on a collagen matrix with fibroblasts were generated. The histomorphological development after 7 and 14 d revealed close similarity with the non-keratinized gingiva epithelium. Furthermore, as epithelial specific markers synthesis and localization of keratins as well as the deposition of basement membrane components were assessed on frozen sections by immunofluorescence and keratin expression by in situ hybridization. Primary keratinocytes in conventional culture strained positive for keratin K14 and the mucosal differentiation-specific keratins K4 and K13, while primary fibroblasts, isolated from the same tissue source, and also some keratinocytes, were positive for vimentin. In organotypic co-cultures the keratinocytes formed a multilayered epithelium within 14 d containing basal cells and flattened cells in the uppermost layers. Comparable to native non-keratinized gingiva keratin 14 gene expression was clearly detectable in the basal cell compartment but showed extending immunolocalization. In addition, particularly at the early stage (7 d), basally located keratinocytes were also vimentin positive. According to morphological differentiation K4 and K13 were detectable in suprabasal position a the RNA and protein level. The major basement membrane constituents collagen type IV and laminin increased with time revealing first an interrupted and later a fully extended staining underneath the basal cells. Maintenance of basal cell function was further demonstrated by cell proliferation (BrdU incorporation) which was initially high (7 d) but declined towards the later stages (14-21 d). The results demonstrate i) that this co-culture system leads to a stratified surface epithelium with morphological and biochemical characteristics of the non-keratinized gingiva epithelium and ii) that a state of physiological tissue balance was reached, thus rendering a suitable model for tissue compatibility studies.

Basement Membrane↗

Early maxillary orthopedics in a child with an oblique facial cleft.

OBJECTIVE: Oblique facial clefts are extremely rare. In view of their variability, surgical treatment cannot be standardized. To date, early maxillary orthopedics in the treatment of oblique facial clefts have not been reported. The case described here presents a newborn child with a Tessier 3 cleft. Because of the enormous width of the alveolar cleft, a narrowing of the segments was regarded as prerequisite for definitive lip closure. To bring the segments together, an actively working plate with a forward pull was designed. CONCLUSION: After a period of 4 weeks, proper alignment and proximity of the segments were achieved, so that definitive lip closure and plastic reconstruction of the remaining soft tissue defect could be easier performed.

Abnormalities, Multiple↗

Dentofacial changes in patients with Class III malocclusions treated by a combination of activator and chin-cup appliances.

The purpose of this study was to examine, on pre-treatment and post-treatment lateral cephalograms, the effects of combined activator/chin-cup therapy on Class III patients, and to compare mean cephalometric differences noted during treatment with untreated Class I subjects. Fourteen females and fifteen males who exhibited a Class III malocclusion were the subjects of the study. Direct comparison of the mean value changes of the cephalometric variables during treatment of Class III patients with untreated Class I subjects revealed that SNA increased more and SNB increased less in the Class III patients than in the control group, thus improving the ANB angle. At the end of treatment, all patients had a positive overjet but a more concave profile. In this study, combined activator/chin-cup therapy seemed to induce improvement in those Class III patients selected for their moderate condition and treated over a five-year period. The changes seemed to indicate growth patterns which imitate those of the untreated Class I subjects. Moreover, dentoalveolar compensations helped to improve the overjet and conceal skeletal deviations.

Activator Appliances↗

Quo vadis?

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Germany↗

Mechanical stretching of periodontal ligament fibroblasts--a study on cytoskeletal involvement.

To investigate molecular aspects of the mechanism(s) involved in orthodontic tooth movement, periodontal ligament fibroblasts (PDL) were isolated and grown on culture dishes with a flexible bottom. The cells were stimulated by stretching the bottom of the culture dishes and whole cell extracts were prepared and subjected to sodium dodecyl sulfate polyacrylamide (SDS-PAGE) electrophoresis, electrotransferred to nitrocellulose membrane and immunoprobed with antibodies specific for vimentin and alpha- and beta-tubulin. No apparent alterations in the expression profile of the above mentioned major cytoskeletal elements were evident after mechanical stretching. Moreover, immunofluorescence against the same proteins revealed no changes in their topographical organisation between stretched and unstretched cell cultures.

Blotting, Western↗

A clinical report for distalizing maxillary molars by using super-elastic wires.

A class II/2 malocclusion with considerable amount of crowding was treated non-extraction by distalization. The upper molars were moved posteriorly with the use of superelastic wires. The orthodontic therapy-mode is presented and the results are discussed. This treatment approach shows another use of superelastic wires.

Adult↗

Skeletal and dentoalveolar changes after extraction of the second molars in the upper jaw.

The aim of this study was to evaluate treatment results after extraction of maxillary second molars. Since this therapy was chosen in patients with class II malocclusion, deep overbite and counterclockwise growth pattern, its effects on overbite and correction of the malocclusion were examined. For this purpose pre- and post-treatment models of 25 patients with 48 extracted upper second molars were measured and lateral cephalograms were appropriately superimposed in order to determine maxillary and mandibular skeletal and dentoalveolar changes. Our results indicate an average overbite reduction from 4.7 mm to 2.7 mm. None of the patients showed a posttreatment overbite increase. Despite the considerable initial Class II relation in many cases, a Class I occlusion was achieved in 92% of the patients. Primarily, the correction was achieved by distalization of the upper first molars. Furthermore, the mesial migration of the lower first molars, skeletal changes in the lower jaw, and the growth inhibition in the upper jaw contributed to the correction of the class II malocclusion.

Adolescent↗

Modification of the agar overlay assay: assessment of the influence of acrylics used in orthodontics on proliferation and differentiation of primary and transformed fibroblasts.

In orthodontics, removable acrylic appliances are preferably produced from methylmetacrylates. However, in the adjacent oral mucosal tissue, cell damage may be caused by the evaporation of residual monomer. The aim of this study was to modify the classic agar overlay assay in order to apply histochemical methods by comparing conventionally used transformed mouse fibroblasts (L-929) with primary human gingival fibroblasts to further elucidate the term toxicity. While proliferation was assessed via the incorporation of the base analogon bromdesoxyuridine, differentiation was investigated by detection of the fibroblast-specific intermediate filament vimentin. After the monomers had taken effect, reduced proliferation extending over the inhibition area was observed by indirect immunofluorescence, independent of cell type. In contrast to this observation, a few cells within the inhibition area which could not be clearly detected by neutral red staining still exhibited mitotic activity. Detection of the differentiation-specific intermediate filament vimentin was comparable with the degree of neutral red fading visible in the classic agar overlay assay. The study showed that the inhibition areas with primary gingival fibroblasts were smaller (approximately 1/3) after monomer action compared with conventionally applied transformed fibroblasts. The results indicate that the modified assay is comparable with the classic method. Evaluation of neutral red staining with respect to toxic material influence can moreover be supplemented by histochemical studies of typical cell properties.

Acrylic Resins↗

Fluoride released from orthodontic bonding agents alters the enamel surface and inhibits enamel demineralization in vitro.

In this study, we examined two fluoride-releasing orthodontic agents in respect to fluoride release, enamel demineralization inhibition, as well as alterations observed on the enamel surface after their use. Fluoride release was found to occur in the highest concentrations within the first 24 hours for both materials examined. After this period, a dramatic decline in fluoride release was observed in both adhesives, and after 90 days no fluoride was detectable. Both fluoride-releasing materials showed significant differences on enamel demineralization around the brackets when compared with a conventional adhesive, and the agent with the initial higher amounts of fluoride release showed the best results. Scanning electron microscopy of the enamel surface revealed particle depositions of microglobular form, after the examined adhesives were used. These particles most likely represent deposition of calcium fluoride, a salt with clearly cariostatic properties. The results of this in vitro study show that certain fluoride-releasing orthodontic bonding systems may provide an additional degree of safety against caries susceptibility in patients with fixed appliances for a limited period.

Adhesives↗

Extraction of maxillary second molars in the treatment of Class II malocclusion.

The results of treatment following the extraction of maxillary second molars for Class II correction were evaluated. Records (cephalograms, orthopantomograms, and models) of 32 patients treated with maxillary second molar extraction were analyzed. Cephalograms taken before and after treatment were traced and 18 variables were compared. Changes in the axial inclination of the erupted third molars relative to the occlusal plane were measured on the orthopantomograms. The form and the position (eruption in occlusion, rotations) of the maxillary third molars were evaluated on the models. The average treatment time was 26 months. The results of this study show significant changes of the angles SNA, SNB, ANB, 1/4:SN, and the distances 1-NPog, and 1-APog, as well as significant effects on the soft tissue profile. In 19 cases examined 4 years postretention, all maxillary third molars had erupted into occlusion with a mesial contact point and acceptable mesiodistal axial inclination.

Adolescent↗

[Neon-colored plastics for orthodontic appliances. Biocompatibility studies].

Public concern and issues of liability have made product safety a major concern throughout the medical field including orthodontics. The purpose of this study was to test the biocompatibility of the new neon colored plastic materials to be used for removable orthodontic appliances before they reach the market and are used in patient treatment. In addition, eight modifications of this synthetic material, which has been used in appliances for many years, were examined without neon color. The procedures established tested for: 1. mutagenicity, 2. toxicity, and 3. irritation of the mucous membrane. As alternatives to using animals the Ames Test, the Agar Overlay Assay, and the HET-CAM Test were employed to test for these properties. The tests revealed that, when the manufacturer's instructions are followed, neither the polymerized materials as used in patient appliances nor the shavings resulting from the orthodontist or the technician grinding the appliance exhibit mutagenic, toxic, or irritating properties.

Animals↗

Case report RS: guided tissue regeneration precedes tooth movement and crossbite correction.

This patient presented with a Class III malocclusion and an anterior crossbite. Although spaces were present distal to the mandibular canines, the alveolar ridges were greatly atrophied. New bone was acquired through guided tissue regeneration. The alveolar ridges were augmented, followed by successful orthodontic tooth movement and correction of the Class III relationship and the anterior crossbite.

Alveolar Process↗

[Hypodontia: considerations on orthodontic therapy in agenesis of the permanent upper lateral incisor].

The authors have investigated different clinical cases having in common the agenesis of the permanent upper lateral incisors, to evaluate from a clinical and esthetic point of view the possibilities, results and the limits of the orthodontic treatment. These are nowadays increasingly associated with esthetic dentistry, prosthodontics, implantology and finally with dental transplantation. The patients presented the absence of one or both permanent upper lateral incisors or the agenesis of other teeth, sometimes associated with dental crowding or a not favourable intermaxillary relation. Most of the cases were treated with compensatory extraction of the other normal or hypoplastic permanent upper lateral incisor. The results were satisfactory but the mean treatment time was relatively long (56 months, including the retention phase), according to the difficulty of obtaining a good esthetic result in the smile line. The importance of a correct point of time of the interception for the choice of the most adequate therapy is emphasized. The possibility of correcting occlusal relation by means of the orthopedic treatment of the maxillary structures is limited to the end of the deciduous dentition. The diagnostic criteria for a correct and opportune interception of this anomaly are being stressed on. Finally the esthetic problems arising of the orthodontic space closure and the possible solutions were discussed.

Adolescent↗