T.M. Präger

Dental findings in patients with ectodermal dysplasia.

Background:Ectodermal dysplasia is an inherited disease caus ing malformations of all tissues originating from the ectoderm. The significance of this disease lies in severe hypodontia, and an accompanying hypoplasia of the alveolar process. The clinical situation is aggravated by a significant xerostomia. It was the aim of this study to document the distribution of hypodontia and tooth malformation. Furthermore, we aimed to elucidate the clinical impact of these findings.Patients and Methods:Records of 30 patients (19 males, 11 females) suffering from ectodermal dysplasia were included. Their age ranged between 7 and 23 years. All patients had been examined clinically and radiographically. In every patient, a record was made of which teeth were missing or malformed, and which deciduous teeth persisted. Additionally, the entire treatment procedure was assessed.Results:The third molars were missing in all of the patients. The number of aplastic permanent teeth ranged from 2 to 26. The maxillary lateral incisors were most frequently absent, followed by the mandibular central incisors. The most stable teeth were the central incisors of the upper jaw, and the canines and first molars in both jaws. However, the maxillary central incisors and canines were the teeth most affected by malformation. Deciduous canines and second molars were the most often persisting teeth due to agenesis of the maxillary lateral permanent incisors and mandibular second premolars. In two-thirds of the patients, missing teeth were replaced by removable dentures. Half of the patients received orthodontic treatment.Conclusions:Hypodontia and malformation are almost regular dental characteristics in patients suffering from ectodermal dysplasia. The distribution of absent teeth deviates remarkably from the general population. Treatment requires an interdisciplinary approach including orthodontics, prosthodontics and oral surgery.ZusammenfassungHintergrund:Ektodermale Dysplasie ist eine erblich bedingte Erkrankung, die Missbildungen der vom äußeren Keimblatt abstammenden Gewebe verursacht. Im Vordergrund stehen Hypodontie, koronale Formanomalie und die Hypoplasie der nicht zahntragenden Alveolarfortsätze. Die klinische Situation wird häufig durch Xerostomie verschlechtert. Ziel dieser Untersuchung war es, die Verteilung der Hypodontie und Zahnmissbildungen sowie ihrer klinischen Konsequenzen zu dokumentieren.Patienten und Methodik:Es wurden 30 Patienten (19 männlich, 11 weiblich, Alter zwischen 7 und 23 Jahre), die an ektodermaler Dysplasie leiden, einbezogen. Von allen Patienten wurden die klinischen und röntgenologischen Befunde ausgewertet und bei jedem die fehlenden und missgebildeten bleibenden Zähne sowie persistierende Milchzähne erfasst und die Häufigkeit dieser Merkmale für jeden Zahn dargestellt. Ferner wurde die interdisziplinäre Therapie dokumentiert.Ergebnisse:Bei allen Patienten fehlten die Weisheitszähne. Die Anzahl der Nichtanlagen anderer bleibender Zähne betrug zwischen 2 und 26. Am häufigsten fehlten die oberen seitlichen Schneidezähne, gefolgt von den unteren mittleren Schneidezähnen. Am stabilsten waren die Anlagen der mittleren Schneidezähne im Oberkiefer sowie der Eckzähne und der ersten Molaren in beiden Kiefern. Jedoch waren die oberen mittleren Schneidezähne und die Eckzähne am häufigsten von Formanomalie betroffen. Milcheckzähne und zweite Milchmolaren persistierten häufig, wenn bleibende seitliche Schneidezähne im Oberkiefer und zweite Prämolaren im Unterkiefer nicht angelegt waren. Zwei Drittel der Patienten wurden mit Kinderprothesen versorgt, die Hälfte der Patienten befand sich in kieferorthopädischer Behandlung oder hatte eine kieferorthopädische Therapie bekommen.Schlussfolgerungen:Hypodontie und Formanomalien sind fast regelmäßige Erscheinungen bei Patienten mit ektodermaler Dysplasie. Deren Verteilung auf die einzelnen Zahntypen unterscheidet sich aber beträchtlich von der in der allgemeinen Population. Ihre Behandlung erfordert ein interdisziplinäres Vorgehen unter Einbeziehung der Kieferorthopädie, Prothetik und zahnärztlichen Chirurgie.

Remodeling along the Bone-screw Interface

Objective:The stability of cortical miniscrews depends on the contact between bone and implant. The aim of this study was to compare bone remodeling along the contact surface between the screw and bone with and without pre-drilling.Materials and Methods:Twenty-four FAMI miniscrews (length 10 mm, diameter 2 mm) were inserted into the mandibular alveolar process apical to the premolars of four miniature pigs. Each pig received six screws, three on the one side with pre-drilling, three on the other side without pre-drilling. Polychrome fluorescent labels were used to assess the bone remodeling. After 12 weeks of osseointegration, all 24 screws and surrounding bone were removed. Microsections were prepared and analyzed histomorphometrically and under fluorescent microscopy. Differences between the groups were determined using the t test with a significance level of 5%.Results:All the screws osseo-integrated without any complications. Those without pre-drilling revealed a bone-screw contact of 64 ± 11%, and those subjected to pre-drilling 63 ± 12%. This difference was not significant. The mineral apposition rate, 1.6 ± 0.4 μm/d and 1.7 ± 0.4 μm/d, respectively, also failed to demonstrate any significant differences between the groups, while the portion of newly-formed bone in the pre-drilled group was significantly higher (59 ± 9% vs. 27 ± 6%).Conclusion:Significant differences in the bone-to-screw contact between the two groups are no longer in evidence after three months due to new bone formation. The minor extent of bone remodeling in the not pre-drilled group rules out substantial bone damage, which might have occurred during screw placement as a result of “cracks” or an excessive increase in pressure along the interface. The similar rate of new bone formation in both groups speaks against a stimulating effect of pre-drilling. Despite the absence of quantitative differences, it remains unclear whether the mechanical quality of the newly-formed bone resembles that of preexisting bone.Our findings seem to be applicable to the human mandible, however, its thinner cortical layer means less screw-to-bone contact is likely. We must reckon with less bone contact in the maxilla for the same reason.ZusammenfassungZiel:Die Stabilität kortikaler Verankerungsschrauben ist abhängig vom Knochen-zu-Schraube-Kontakt. Ziel dieser Studie war es, den Knochenumbau an der Kontaktfläche zwischen Schraube und Knochen mit und ohne Vorbohrung zu vergleichen.Material und Methodik:24 FAMI-Verankerungsschrauben (Länge 10 mm, Durchmesser 2 mm) wurden bei vier Miniaturschweinen in den Unterkieferalveolarfortsatz des Prämolarengebietes inseriert. Jedes Schwein erhielt sechs Schrauben, drei auf der einen Seite mit Vorbohrung, drei auf der anderen ohne Vorbohrung. Um den Knochenumbau zu beurteilen, wurden polychrome Fluoreszenzmarkierungen durchgeführt. Nach 12 Wochen Einheilung wurden alle 24 Schrauben mit umliegendem Knochen entfernt. Dünnschliffpräparate wurden angefertigt und histomorphometrisch und fluoreszenzmikroskopisch untersucht. Unterschiede zwischen den Gruppen wurden mit dem t-Test auf dem 5%-Niveau überprüft.Ergebnisse:Alle Schrauben heilten komplikationslos ein. Bei den Schrauben ohne Vorbohrung bestand ein Schraube-zu-Knochen-Kontakt von 64 ± 11%, bei denen mit Vorbohren von 63 ± 12%. Dieser Unterschied war nicht signifikant. Auch die Mineralappositionsrate zeigte mit 1,6 ± 0,4 μm/d bzw. 1,7 ± 0,4 μm/d keinen signifikanten Unterschied zwischen den Gruppen, wohingegen der Anteil neu gebildeten Knochens in der Gruppe mit Vorbohrung signifikant höher war (59 ± 9% vs. 27 ± 6%).Schlussfolgerung:Signifikante Unterschiede des Knochen-zu-Schraube-Kontakts zwischen beiden Gruppen sind infolge der Knochenneubildung nach drei Monaten nicht mehr nachweisbar. Der geringe Knochenumbau in der Gruppe ohne Vorbohrung schließt eine erhebliche Knochenschädigung aus, die bei einer Schraubenplatzierung, zum Beispiel durch „Cracks“ oder übermäßige Drucksteigerung an der Kontaktfläche, denkbar wäre. Die vergleichbare Knochenneubildungsgeschwindigkeit in beiden Gruppen spricht gegen einen stimulierenden Effekt der Vorbohrung. Trotz des Fehlens quantitativer Unterschiede bleibt zu zeigen, ob die mechanische Qualität des neu gebildeten Knochens mit der des ortsständigen Knochens vergleichbar ist.Prinzipiell erscheint eine Übertragung der hier gefundenen Ergebnisse auf den menschlichen Unterkiefer wahrscheinlich, jedoch ist wegen dessen dünnerer Kortikalisschicht ein geringerer Schraube-zu-Knochen-Kontakt zu erwarten. Im Oberkiefer ist aus dem gleichen Grunde mit weniger Knochenkontakt zu rechnen.

Effect of methotrexate upon antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of methotrexate (MTX) on AIA in rabbits by means of three different histological staining methods. METHODS After sensitization, a bilateral arthritis of the TMJ was induced by an intra-articular administration of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, six of the 12 rabbits received weekly intramuscular injections of MTX, and the other six animals remained without therapy. Another six animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with haematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score and tartrate-resistant acid phosphatase (TRAP). RESULTS In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the MTX group, the signs of cartilage degeneration were significantly reduced compared with the arthritis group. In contrast, the joints in the control group were inconspicuous. A correlation between the Mankin score and TRAP-positive cells could be found. CONCLUSIONS Systemic administration of MTX seems to have a positive effect upon the inflammatory process in the rabbit TMJ but fails to eliminate the sign of arthritis completely.

Effect of methotrexate on the mandibular development of arthritic rabbits.

INTRODUCTION Juvenile idiopathic arthritis affecting the temporomandibular joint (TMJ) can cause severe disturbances of the mandibular development. Methotrexate (MTX) is often administered as a common used remission-inducing agent to treat this disease. The aim of this study was to investigate the effect of low dose MTX on the mandibular growth in arthritic rabbits. SUBJECTS AND METHODS Eighteen 10-week-old female New Zealand white rabbits were randomly assigned to three groups with six animals in each group. After being sensitized to ovalbumin (OA), the first and the second group received intra-articular injections with OA. The first group remained untreated, the second was treated by weekly injections of MTX. Cephalograms were taken from each animal at 10, 13, 16, 19, and 22 weeks of age and six mandibular distances measured. RESULTS All distances showed an increase between 10 and 20 per cent, whereas growth was more accentuated in the sagittal dimension. Significant differences in the overall growth could be observed between the arthritic and the control animals and less accentuated between the arthritic and the MTX animals. In contrast, existing differences between the groups were not significant during the intervals, but time had the greatest influence on mandibular growth. CONCLUSIONS MTX seems to have a positive impact on growth in rabbits suffering from experimental arthritis of the TMJ.

Histomorphometry in antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of the tumor necrosis factor-alpha (TNF-α) antagonist etanercept on AIA in rabbits by means of three different histological staining methods. METHODS After sensitization, a bilateral arthritis of the TMJ was induced and maintained by repeated intra-articular administrations of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, 6 of the 12 rabbits received weekly subcutaneous injections of etanercept, and the other 6 animals remained without therapy. Another 6 animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with hematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score, and tartrate-resistant acid phosphatase (TRAP). RESULTS In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the etanercept group, the signs of cartilage degeneration were significantly reduced but present. In contrast, the joints in the control group were inconspicuous. A strong correlation between the Mankin score and TRAP-positive cells could be found. CONCLUSIONS Antigen-induced arthritis causes severe damage in the TMJ of young rabbits. An improvement seems to be achievable by a systemic administration of etanercept.