[Importance of tooth root resorption in the differential diagnosis of cystic bone processes in x-ray pictures].
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Changes in bone, cartilage and the dentition in animals and man following the administration of anticonvulsant drugs resemble those seen in hypoparathyroidism and pseudohypoparathyroidism. Groups of 21-day-old rats were treated with diphenylhydantoin, parathyroidectomized, or made hypocalcaemic with a calcium-deficient diet. Histological examination revealed extensive resorption of cementum and dentine in the molars of the drug-treated and parathyroidectomized rats, but not in the hypocalcaemic or control groups. Localization of injected tetracycline by fluorescence showed that the resorption affected the distal side of the tooth roots and had occurred after root formation. No changes in cementum formation on the mesial side of the roots had occurred in any of the experimental groups. These results suggest that diphenylhydantoin induces a condition similar to pseudohypoparathyroidism in which the resistance of tooth roots to resorption is reduced.
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The varying extent of permanent tooth resorption attributable to different types of orthodontic appliances is a continuing cause for concern. This paper reviews recent researches which contribute to an improved understanding of the origin and behaviour of osteoclasts; and considers the structure and behaviour of the periodontal ligament and its relationship to the cementum and bundle bone of the tooth socket. Permanent tooth resorption is identified as a normal phenomenon. A simple explanation is offered as to why under normal circumstances the bone of the tooth socket is more likely to be resorbed than the tooth itself. With this knowledge treatment procedures can be selected which will reduce tooth resorption risks to a minimum.
The toothless (tl) rat is an osteopetrotic mutation characterized by a generalized skeletal sclerosis, reduced bone resorption, few osteoclasts and a total absence of erupted teeth. This mutation is not cured by bone marrow transplants from normal littermates. It is known that the skeletal defects in tl rats are greatly improved after treatment with colony-stimulating factor-1 (CSF-1). This investigation concerns the effects of CSF-1 on the development and eruption of the dentition of tl rats. Untreated tl rats had no erupted teeth by 56 days after birth, and the roots of incisors and molars were severely distorted by compression against bone. The apex of the mandibular incisor did not extend past the first molar and continued growth of its apical end produced odontoma-like masses consisting of distorted dentine and enamel matrices. In addition, few osteoclasts were seen on alveolar bone surfaces surrounding the developing teeth. Mutants given CSF-1 were characterized by delayed eruption of all molars and sometimes incisors. The incidence of incisor eruption was related inversely to the age at which CSF-1 treatment began. Molars of treated tl rats had well-developed roots similar to those in normal rats. Treated mutants had numerous osteoclasts in alveolar bone and well-developed haemopoietic marrow spaces in the mandible. Histochemical staining for both tartrate-resistant acid phosphatase and tartrate-resistant acid ATPase was reduced or negligible in osteoclasts of untreated tl rats, heavy in normal osteoclasts and of intermediate intensity in CSF-1-treated mutants.(ABSTRACT TRUNCATED AT 250 WORDS)
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Tooth eruption depends on bone resorption to form an eruption pathway. We have previously shown that a 2-wk local infusion of bafilomycin A1, an inhibitor of vacuolar H(+)-ATPases in osteoclasts, into the crypts of erupting mandibular premolars in dogs blocks bone resorption during this period and eruption of these teeth is delayed for 8 wk. Here we report the limits of inhibition of resorption that still permit eruption of these teeth. In 3 dogs 10(-6) M bafilomycin was delivered by osmotic minipumps early (18 wk) in eruption to the fourth premolar for 1, 3 or 4 wk. Radiographs taken at weekly intervals thereafter showed that bafilomycin delivery for 1 wk delayed eruption for 3 wk, delivery for 3 wk delayed eruption 9 wk and delivery for 4 wk prevented eruption. These data show that tooth eruption is delayed in direct proportion to the time resorption is blocked, and that this process for dog premolars cannot be blocked for more than 3 wk with 10(-6) M bafilomycin without blocking eruption itself.
Tartrate-resistant acid phosphatase (TRAP) has been used as a cytochemical marker for the cell mediators of bone resorption, osteoclasts and their mononuclear precursors. We have applied a cytochemical method for TRAP to study the dependence of the osteoclast-mediated bone resorption of tooth eruption on the dental follicle, a connective tissue investment of the developing tooth, by analyzing the TRAP activity of mononuclear cells in the dental follicle before and during pre-molar eruption in dogs. The percentage of TRAP-positive monocyte cells increases until mid-eruption, slightly preceding a previously demonstrated rise in numbers of osteoclasts on adjacent bone surfaces. These data suggest an ontogenetic relationship between follicular mononuclear cells and osteoclasts on adjacent alveolar bone surfaces during tooth eruption. However, because TRAP occurs in other tissues and is not an exclusive indicator of pre-osteoclasts, proof of their relationship will have to await application of more definitive techniques.
The behaviour of eruption of lower premolars after pathological resorption of deciduous molar roots was examined on models and X-rays. The molars of the first dentition were shed earlier after pathological resorption of deciduous molar roots. Data of absence are measured in years in the presence of occlusal bone bridges. The middle values are more than three years. Eruption of permanent teeth happens years later or they remain impacted. Eruption dates of premolars after pathological deciduous root resorption and interruption of the lamina dura, and after physiological resorption are significantly earlier than if there is an occlusal bony bridge (p less than 0.01). The therapeutic consequence is the surgical liberation of such premolars and their removal.
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It has been shown that a specific inhibitor of vacuolar H(+)-ATPases, bafilomycin A1, inhibits bone resorption by isolated chicken osteoclasts by blocking the proton pump in the ruffled border membrane. We report here the effects of bafilomycin A1 on bone resorption in vivo. Using a cannulated osmotic minipump delivery system, we infused bafilomycin locally to the eruption pathway of permanent premolars of beagle dogs. We used pit formation by osteoclasts in vitro to estimate the concentrations and heat stability of bafilomycin to be used in vivo. In this model, osteoclasts were cultured on thin bone slices, in which they form pits indicative of resorption. After 2 weeks preincubation at 37 degrees C, bafilomycin concentrations of 10(-6) and 10(-7) M but not 10(-8) M completely inhibited the resorptive activity of cultured osteoclasts, and the two larger doses were chosen for use in vivo. Local delivery of 10(-6) M bafilomycin to the eruption pathway of the fourth permanent mandibular premolar during mideruption inhibited tooth eruption by blocking bone resorption as assayed by radiography, light microscopy, and scanning electron microscopy. Bafilomycin at 10(-7) M had similar but less intensive effects. Moreover, osteoclasts in the alveolar bone of crypts treated with 10(-7) M bafilomycin A1 stained very weakly for tartrate-resistant acid phosphatase. The effect of bafilomycin on bone resorption was shown to be very local, and no side effects of treatment with bafilomycin were observed in adjacent teeth or the behavior of dogs. We report here, for the first time, inhibition of tooth eruption caused by inhibited bone resorption using bafilomycin A1 in vivo.
The purpose of this study was to determine the role of the pressure generated during the intraligamentary injection technique on the occurrence of root and bone resorptions in dogs. Five beagles were used in the study, and interventions were scheduled to provide observation periods at 7, 25, and 45 days. One hundred five sites on the dogs were divided into three groups: (1) those subjected to needle penetration; (2) those subjected to saline solution injection; and (3) the control sites. Injections were made with a specially designed syringe equipped with a miniaturized force transducer. The dogs were then killed, and block sections of the sites were made and treated in accord with standard histologic procedures. The mean number of osteoclasts and odontoclasts was calculated for each group, and the mean value of bone and tooth resorption angle was measured. Data were then analyzed statistically. Results showed that, at 7 days, needle penetration and saline solution injection caused osteoclastic activity and bone resorption; the number of osteoclasts and the extent bone resorption were greater in the group that received the injection of saline solution. No difference was found for the odontoclastic activity and tooth resorption. A correlation was found between the force developed during injection, the mean number of osteoclasts, and the mean angle of bone and tooth resorption. At 25 and 45 days, healing had occurred. These findings suggest that fluid pressure within the periodontal ligament is sufficient to initiate osteoclastic, reversible bone resorption.
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Previous studies have shown that chronic dietary deficiency of calcium can result in more rapid orthodontic tooth movement. The purposes of this study were to confirm that finding in a calcium-deficient, lactating rat model and to quantify the degree to which the area of root surface resorption is affected by these conditions. Thirty-five adult female Sprague-Dawley rats were divided into two groups: (1) nonlactating animals on a control diet and (2) lactating animals on a calcium-deficient diet. A 60-gm orthodontic force designed to tip maxillary molars mesially was applied for varying times. At sacrifice, tooth movement was quantified by measuring the space created between maxillary molars; percent bone ash was measured for each humerus, and root surface resorption was estimated by means of a morphometric technique to measure the area of cratering on the mesial roots of first molars. Both groups showed a typical two-phased tooth movement cycle lasting for 10 days, although the magnitude of movement was significantly greater (p less than 0.001) in the test animals. The "humerus" test from animals exhibited a significantly decreased (p less than 0.001) fat-free dry weight, ash, and percent ash weight. The test group also displayed a significantly reduced percent area of root surface resorption (p less than 0.05) by 7 and 10 days following appliance activation. These findings confirm earlier observations that lactation, coupled with calcium deficiency, will produce decreased bone density which is consistent with increased parathyroid hormone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
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