Tablet fluoridation influences the calcification of primary tooth pulp.

This study was conducted to determine the influence of long-term tablet fluoridation on primary pulp calcification by light microscopy. Twenty-four caries-free primary molars (after continuous postpartally initiated 1- to 10-year tablet fluoridation) were compared to 17 primary molars of children without fluoride prophylaxis. Pulp calcification in children with tablet fluoridation was significantly more frequent and more pronounced than in untreated children (p = 0.001). Besides the known pulp stones, the prophylaxis group evidenced a special form of calcification consisting of fibrodentin-like hard tissue not observed in the untreated children. These hard tissue bodies developed "intramurally" on the pulp floor and the inside of the dental roots with an irregular extramural spread into the coronal and radicular pulp by displacement and fibrotization of the pulp tissue. Moreover, some of the teeth had more or less extensive areas of interglobular dentin. The affected teeth were ankylosed in the area of the bi- and trifurcation and on the inside of the roots and were thus infra-occluded. Although the duration of tablet fluoridation has no statistically significant influence on pulp calcification, there is a correlation between extensive pulp calcification, postnatally initiated fluoride prophylaxis and the infraocclusion of primary molars.

Acceleration in dental development: fact or fiction.

The aim of this investigation was to determine whether an actual acceleration in dental development has taken place over the last 30 years in a European population group, as is so readily observable in relation to body height. In this study, radiographs of 1038 healthy European children, 516 boys and 522 girls, were evaluated. The methodology and norms given by Nolla (1960) for both sexes were used and compared with the tooth developmental stages in our subjects. In girls, no difference to Nolla's norms could be detected. However, in boys, dental development has accelerated. This difference was most apparent in the 3- to 9-year-old age group and was statistically significant. Thus, over the last 30 years, a small acceleration in dental development has taken place in very young males.

[The significance of preventive CNS irradiation during antineoplastic therapy in childhood with regard to late odontogenic and mandibulofacial injuries]. / Die Bedeutung einer präventiven ZNS-Bestrahlung im Rahmen einer antineoplastischen Therapie im Kindesalter hinsichtlich dentogener und mandibulofazialer Spätschäden.

The aim of the present study was to determine the adverse effects of antineoplastic chemotherapy and radiotherapy on tooth development, i.e., on dentition in general and on craniofacial growth. The patients studied consisted of 26 children with solid tumors treated with chemotherapy alone and 34 patients with acute lymphoblastic leukemia (ALL) who were treated with intensive and follow-on radiation therapy (18 and 24 Gy) to the neurocranium as a constituent of central nervous system prophylactics in treatment protocols for ALL. The treatment protocol employed in these children is known as the BFM (Berlin, Frankfurt, Münster) protocol. At the time of diagnosis the children ranged in age from 3 to 52 months. All treated patients had microdontia, enamel dysplasia, thinning and tapering of apical roots portions, and marked shortening of the roots. These defects were more pronounced in children treated for ALL, but it was not possible to establish statistically relevant evidence on the influence of adjuvant radiotherapy in this group. This indicates that there is a catch up in craniofacial growth 9 years after therapy and that the most serious long-term adverse effects are on dentition.

Response of odontoblast-like cells to hydroxyapatite ceramic granules.

In this study the inductive influence of hydroxyapatite ceramic (HAC) granules on preodontoblast differentiation was investigated. Dental papilla cells harvested from upper molar tooth germs were implanted intramuscularly in a pouch created for this purpose. Six months after surgery tooth-root-like bodies had developed with pulp-like cavities in the specimens in which dental papilla cells had been implanted with and without HAC. These bodies consisted of regular tubular dentine in the central part, fibrodentine peripherally and sometimes osteodentine. HAC was haphazardly enclosed in these root-like bodies, whereas the implantation of HAC alone had no effect.

[Cephalometric studies on the mandible following the dorsal transposition of the masseter. An experimental animal study]. / Kephalometrische Untersuchungen am Unterkiefer nach dorsaler Massetertransposition. Eine tierexperimentelle Untersuchung.

Changes in growth dimension and growth direction in three to four week old rabbits were studied cephalometrically after surgically repositioning the anterior part of the superficial masseter muscle dorsally to the angle of the mandible (n = 14). Only a sham operation was performed on 13 animals. Twelve months after the procedure the lower jaws were taken out and cleaned by boiling. X-rays were taken of the right and left part of the mandible. All x-rays were measured cephalometrically and the measurements evaluated statistical (alpha = 0.05) with the U-test (Mann/Whiteney). We found a statistically significant shorter mandible and an enlargement of the gonion angle, which indicate a vertical growth direction. The processus condylaris was unchanged. It can be assumed that the growth of the mandible can be altered permanently by muscle reposition, especially in cases with dysmoysis, a term in the literature first proposed by Eschler.

Attachment of cementum on different hydroxylapatite ceramic (HAC) substrata in vivo. A light and electron microscopic study.

The role of substrate surface characteristics for periodontal regeneration was studied in rats. Cementogenesis was initiated by dental follicle cells retained after dissecting out a molar tooth germ in 5-day-old rats. The tooth germ was substituted by a bone replacement material, namely HAC granules of porous consistency. Tissue blocks were removed after 24 weeks and processed for light and electron microscopic examination. On all HAC surfaces a new cementum-like tissue developed, similar to that of natural root surfaces. The results strongly indicate that the exposure of collagen fibers is not essential in order to achieve new periodontal attachment.

[The osteoplastic care of the cleft jaw--an advance for the orthodontic treatment of cleft patients?]. / Die osteoplastische Versorgung des Kieferspaltes--ein Fortschritt für die kieferorthopädische Behandlung des Spaltpatienten?

This survey deals with problems of osteoplastic supply of the cleft from the orthodontic point of view. Remarkable parallels exist between primary and secondary osteoplasty: The involution stability of the alveolar process is only presented in a space-less tooth line. Therefore, the primary goal is to guarantee tooth eruption in the former cleft area. However, the antalogous bone graft in the former cleft area has to have a similar structure as adjacent alveolar bone. If tooth germs pass through the bone graft, an own parodont can be built up in the course of eruption. This is applicable to both dentitions. Accordingly, the osteoplasty of clefts is the most important prerequisite for stable treatment results and a healthy dentition.

[Physiological tooth migration in hydroxyapatite grafts with bony regeneration. Animal study]. / Physiologische Zahnwanderung in keramo-ossäre Regenerate nach Implantation von Hydroxylapatitkeramik. Tierversuch.

Tooth migration into jaw segments where granular hydroxy apatite had been implanted was studied in rats. To prevent premature contact with the ceramic granules, tooth germs were completely removed in the animals at the age of 10 days. Tooth root contact with the ceramo-osseous complex as a result of physiological tooth migration had deleterious effects. In the light of these findings the implantation of granular hydroxy apatite in the vicinity of tooth roots is not advisable.

[Light, scanning and electron microscopic studies of the substrate dependence in replacement cementum formation]. / Licht-, raster- und elektronenmikroskopische Untersuchungen zur Substratabhängigkeit bei der Ersatzzementbildung.

The cement genesis obviously does not depend on surface parameters such as the exposition of dentin collagen. It can be reproduced on different surfaces of ceramics and is not bound to substrate. The classification primarily depends on the extent of contact of the cement with the substrate surface. However the integration of Interpore 200 seems to be more physiological compared to the integration of pure synthetic ceramics Osprovit. Yet both porous ceramics show no resorption stability and are therefore replaced by substances of cement. The size of the synthetic hydroxylapatite crystals is important to the bonding stability.

[Dental sac and its role in periodontal development]. / Das Zahnsäckchen und dessen Bedeutung bei der Entstehung des Parodontiums.

The present study examined the role of the innermost layer of dental sac tissue in periodontal development. Empty bony crypts were filled with Hydroxylapatite ceramic granules of porous consistency in 5-day-old rats. After 4.5 and 24 weeks the specimens were processed for light and transmission electron microscopy. Only 4 weeks later cement regeneration was seen on ceramic surfaces with bundles of oriented collagen fibers inserting in the cementoid matrix. Ultrastructurally the newly formed cementum-like tissue was in intimate contact to the synthetic hydroxylapatite crystals. A consistent finding was the presence of an interface between cementum and the ceramic surface. The present findings question the unique role of the "investing layer" in periodontal development and the existence of cement-inducting properties of dentin.

[The significance of the gingival ligament system for orthodontic tooth movement--an experimental animal study]. / Die Bedeutung des gingivalen Fasersystems für die kieferorthopädische Zahnbewegung--Eine tierexperimentelle Untersuchung.

In ten six-month-old Wistar rats, we studied tooth movement after fiberotomy. To trace bone remodeling, all rats received two labelling dyes in five days intervals. We found that ligament regeneration is complete after 14 days. Using fluorescence microscopy we found in rats when stretching forces were continued that a reversal of tooth drift takes place in comparison to the control side, indicating an identical behaviour as before. Only in cases with inflammation no fibre regeneration was found and the mesial drift of the neighbouring tooth was missing. Because of these side-effects this procedure seems not to be a useful adjuvant to enhance orthodontic tooth movement.

Stabilization of maxillary segments and dental arch after puberty, in cleft lip and palate cases.

To overcome the high tendency to relapse after orthodontic treatment in patients with cleft lip and palate, efficient stabilisation of the dental arch is essential. In patients with an alveolar defect, extended bridges are most suitable, because there is no need for further retention appliances, the functional and cosmetic results are acceptable and extensive prosthetic reconstruction can be avoided, regardless of the patients age.

Inhibition of tooth eruption through calcium-phosphate ceramic granules in the rat.

This experiment investigated the reason for disturbances of tooth eruption through hydroxylapatite (HA) granules. HA granules of compact and porous structure were implanted in the pathway of erupting teeth in 14 five-day-old rats. The results demonstrate that the use of this material can result in tooth retention and malformed tooth crowns. Tooth crown malformation can be traced to the formation of ceramo-dentinous complexes which promote bacterial invasion of the pulp cavity, resulting in arrest of the tooth eruption process.

[Periodontal reactions to orthodontic forces in the diabetic metabolic state]. / Die Reaktion des Parodonts auf kieferorthopädische Kräfte bei diabetischer Stoffwechsellage.

The reaction of the periodontium to orthodontic tooth movement was studied in rats with streptozotocin diabetes. Forces employed to initiate mesial movement of first molar were 10 N 20 N 30 N and the duration of application was three, six, ten and 14 days. The 14-day rats were treated with fluorochrome sequential labelling according to Rahn. Diabetes mellitus in rats is accompanied by characteristic changes: The most important findings were: 1. a slow osseous regeneration, as could be shown by fluorescence microscopy, 2. the new bone ist unable to pick up the labellings in a sequential manner, 3. a weakening of the periodontal ligamentum, 4. microangiopathies in the gingiva area. the specific diabetic changes are more pronounced following orthodontic tooth movement.

[Periodontal reaction to orthodontic measures]. / Reaktion am Parodontium bei kieferorthopädischen Massnahmen.

In twelve rats, the right maxillary first molar was moved mesially by means of a fixed appliance. It was not possible to find any histopathological differences with forces of 10 N, 20 N and 30 N. We also found no different cellular reactions in the tension and pressure zones between the periods of three, six, ten and 14 days. In the treated rats the first molar was tilted. The mesial root was intruded. Local pressure zones were regularly formed around the mesial root and distal aspect of the alveolar crest of the bifurcation. It could be shown by vital polyfluorochrome staining that there was no mesial tooth movement; rather distal drifting was delayed.

[The effects of premature deciduous molar loss on the succeeding premolars]. / Auswirkungen eines vorzeitigen Milchmolarenverlustes auf die nachfolgenden Prämolaren.

By means of panoramic radiographs of 76 patients we investigated the development and eruption of lower premolars following premature loss of their deciduous predecessor. Following extraction of deciduous molars the mineralization of the bicuspids was accelerated. The eruption of the respective bicuspids took place earlier than expected. During eruption root length was shorter than usual for that stage of development. Although the bicuspids reached occlusion earlier than normal, root mineralization continued to normal length.

Aplasia of primary canines and anlagen of permanent canines: a cleft-specific condition?

The patient is a girl with bilateral cleft lip and palate. It appears that one or more specific teratogens that induce definite malformations are also able to disturb the development of the dentition in an unpredictable manner.