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Idiopathic external resorption of teeth.

An unerupted maxillary third molar tooth from a 57-year-old Caucasian male, which showed radiographic evidence of crown resorption, but was otherwise symptomless, was examined post-extraction by light and scanning electron microscopy. (SEM) Appearances of the residual dental tissues were consistent with a diagnosis of an invading external resorption with formation of pulpal granulation tissue, dentinal resorption and some dentinal metaplasia. SEM of crown fragments indicated a generally uniform pattern of enamel resorption, for which the ameloblasts rather than multinucleate cells were implicated. By extrapolation of the activity of the former cells during the late stages of amelogenesis and tooth eruption, it is suggested that resorptive activity of and by enamel epithelium may explain not only the coronal origin of this type of idiopathic resorption, (which is otherwise unexplained), but also its progress into the pulp and the pulp reactions.

Dental Enamel↗

A transmission electron microscope study of fibroblast changes in human deciduous tooth pulp.

The coronal pulps of four primary canines, free from radicular resorption, and of three primary teeth, with roots entirely resorbed, were prepared for electron microscopy. Mature fibroblasts, similar to those reported in the pulps of permanent teeth, were present in the pulps of the clinically mature teeth. Regression of fibroblasts, evident in the pulps of deciduous teeth at the root resorption stage, was characterized by cytoplasmic changes, modifications in the cytoskeleton and dissociation of cells and fibrils. Deciduous teeth might provide a model for studying pulp fibroblast ageing.

Actin Cytoskeleton↗

Timing of orthodontic tooth movement in a case with traumatized and avulsed anterior teeth.

A traumatic injury to a patient undergoing orthodontic treatment resulted in avulsion, dislodgement, and fracture of upper anterior teeth. Deciding when to institute endodontic treatment and when to resume orthodontic treatment was based upon minimizing the changes for ankyloses and root resorption. Endodontic treatment was carried out two weeks after trauma, and orthodontic treatment continued three weeks after trauma. Radiographs taken six months, one year, and two years after orthodontic completion showed progressive root resorption to the avulsed tooth and minimum root resorption to the remaining anterior teeth.

Adolescent↗

Ultrastructural changes on the root surface in "pressure zone" after experimental movement of teeth in young rats fed a low calcium and vitamin D-deficient diet.

Dietary calcium and vitamin D-deficiency, as a potential biological factor in etiopathogenesis of root resorption occurring during orthodontic tooth movement, still remains controversial. The aim of the present investigation was to assess the ultrastructural changes on the surface of the root in "pressure zone" after orthodontic tooth movement in rats fed a low calcium and vitamin D-deficient diet. The studies were carried out on 20 young Wistar rats. The results from the scanning electron microscopic showed the increased root resorption in "pressure zone" after orthodontic tooth movement in rats fed a low calcium and vitamin D-deficient diet.

Animals↗

Longitudinal radiographical study on the rate of alveolar bone loss in patients of a dental school.

Two sets of radiographs, taken at an interval of 4-14 years in 105 patients of a dental school, were examined in order to determine the rate of resorption of alveolar bone. The percentage loss of maximum alveolar bone height was measured in the interproximal and interradicular sites by means of the Schei ruler. The average percentage of interproximal bone resorption was 0.51% (0.07 mm) per year. Age, sex, professional status, type of periodontal treatment and general state of health did not seem to affect the annual resorption rate. However, crowned teeth had a significantly greater rate of resorption than uncrowned teeth. Loss of bone tended to be more rapid in interdental as compared to interradicular areas. A positive and statistically significant correlation was found between initial resorption and annual tooth loss.

Adolescent↗

Evaluation of apical root resorption following extraction therapy in subjects with Class I and Class II malocclusions.

The purpose of this study was to determine the amount of root resorption during orthodontic treatment, and to examine the relationship between tooth movement and apical root resorption. Twenty-seven Class I and 27 Class II patients treated with edgewise mechanics following first premolar extractions were selected. The following measurements were made on the pre- and post-treatment cephalograms: upper central incisor to palatal plane distance, the inclination of upper central incisor to the FH and AP planes, the perpendicular distances from the incisor tip to the AP and PTV planes, and incisor apex to PTV. The amount of apical root resorption of the maxillary central incisors was determined for each patient by subtracting the post-treatment tooth length from the pre-treatment tooth length measured directly on cephalograms. Intra-group differences were evaluated by the Student's t-test and inter-group differences by the Mann-Whitney U-test. For correlations the Pearson correlation coefficient was used. The results show that there was a mean of approximately 1 mm (P < 0.01) of apical root shortening in Class I patients, but in Class II division I subjects the mean root resorption was more than 2 mm (P < 0.001). The inter-group differences were statistically significant. No significant correlations were found between the amount of apical root resorption and tooth inclination, or the duration of active treatment.

Adolescent↗

Estrogen replacement therapy--something to smile about.

Tooth loss and alveolar residual ridge resorption are significant oral health problems in older adults. Although the causes of tooth loss are many, several studies show an association between tooth loss/residual resorption and systemic osteoporosis. Because estrogen replacement therapy (ERT) slows the development of osteoporosis, we investigated the relationship between estrogen use and tooth loss among elderly women who were participating in the Leisure World Cohort Study. Among 3,921 women 52 to 109 years old (median = 81), those who had ever used estrogen retained more teeth than nonusers (21.2 vs 19.2). The age-adjusted risk of having fewer than 25 teeth decreased with increasing duration of ERT: 0.87 for < 4 years of ERT, 0.74 for 4 to 14 years, and 0.70 for 15+ years compared to nonusers. Similarly, the risk of edentia was inversely related to estrogen use. If a woman had ever taken ERT, her risk of losing all her teeth was about two thirds that of a woman who had never used estrogen. Long-term users (15+ years) had half the risk of becoming toothless. Despite differences in age, education, methods of obtaining tooth and hormone data, and prevalence of tooth loss, two other cohort studies (the Nurses' Health Study and the Framingham Heart Study) reported similar reductions in tooth loss among estrogen users. The data suggest that tooth retention, in addition to being affected by osteoporosis of alveolar bone, also shares in the benefits of ERT on osteoporosis.

Age Factors↗

Parathyroid hormone-related protein induces spontaneous osteoclast formation via a paracrine cascade.

Experiments in vivo have established that tooth eruption fails in the absence of parathyroid hormone (PTH)-related protein (PTHrP) action in the microenvironment of the tooth because of the failure of osteoclastic bone resorption on the coronal tooth surface to form an eruption pathway. To elucidate the effects of PTHrP on osteoclast regulation in this environment, we established primary cultures of epithelial stellate reticulum cells and mesenchymal dental follicle (DF) cells surrounding the teeth. When cocultured, these cells are fully capable of supporting the formation of functional osteoclasts in the absence of added splenic osteoclast precursors, osteoblasts, or vitamin D/PTH/PTHrP. Neutralizing the effects of PTHrP resulted in a decrease in the number of osteoclasts formed, suggesting that stellate reticulum-derived PTHrP drives osteoclast formation. DF cells were found to express functional PTH/PTHrP type I receptors, and conditioned media collected from PTHrP-treated DF cells were able to induce bone resorption in the fetal-rat long-bone assay. PTHrP treatment also induced an increase in osteoclast differentiation factor expression and a concomitant decrease in osteoclastogenesis inhibitory factor expression in DF cells. The addition of osteoclastogenesis inhibitory factor resulted in a decrease in the number of osteoclasts formed in the cocultures, suggesting that osteoclast formation is mediated by osteoclast differentiation factor. Thus, PTHrP seems to regulate osteoclast formation via mediation of the DF, in a manner analogous to the osteoblast-mediated process in the peripheral skeleton. The primary coculture system of dental crypt cells also offers a system for the study of osteoclast formation and regulation.

Animals↗

Experimental autogenous tooth transplantation in the dog: a comparison between one- and two-stage surgical techniques.

Crucial if tooth transplantation is to succeed is preservation of the vitality of the cells of the periodontium and cementum of the tooth graft. Poor contact between the tissues of the recipient site and the root surface when teeth are transplanted to recipient sites prepared immediately prior to transplantation (one-stage technique) could, after transplantation, result in insufficient nutrition to the cells of the root surface and contribute to necrosis of the cells. To improve nutrition, tooth transplantation to recipient beds left to heal for 14 days was performed (two-stage technique). Clinical trials of tooth transplantation by the two-stage technique resulted in a low incidence of tooth graft loss and root resorption. The different results between these two methods, as well as difficulties in evaluating clinical trials, called for an experimental model to be established. In 5 beagle dogs, fully developed autogenous teeth were transplanted using both one-stage and two-stage surgical techniques. The control teeth were transplanted by the one-stage method to recipient beds prepared immediately before transplantation. The test teeth were transplanted using the two-stage method to recipient beds prepared and left to heal for 5 days prior to transplantation. Four pairs of teeth (1 test and 1 control) were transplanted in each dog. One pair of incisors and one pair of premolars were transplanted in the maxilla and in the mandible. Altogether 20 pairs of teeth were included in the study. One pair of teeth fractured during extraction and was therefore excluded from the study. Two pairs of teeth were lost in the first hours after transplantation. Evaluation of the remaining 17 pairs of teeth was made by routine histological examinations after a 6-month period of healing. The blinded examination failed to show a difference between the two surgical methods in terms of frequency of various types of root resorption. The differences between the results after long-term observation of human teeth transplanted by the one- and two-stage tooth transplantation techniques were not found by this experimental model.

Animals↗

Effects of maxillary molar intrusion on the nasal floor and tooth root using the skeletal anchorage system in dogs.

The skeletal anchorage system (SAS) was developed to provide intraoral absolute anchorage for the intrusion or distalization of molars. The purpose of this study was to verify the effects of remarkable molar intrusion on the tooth root and the maxillary sinus floor. Six adult female beagles with fully erupted dentition were used. Titanium miniplates were implanted bilaterally above the maxillary second premolar root apices using pentobarbital anesthesia. The second premolars were intruded for four or seven months after three months of healing after implantation. Standardized dental radiographs were taken periodically to evaluate the amount of tooth movement and root resorption. After the experimental animals were fixed by perfusion at the end of each experimental period, the second premolars were dissected along with the surrounding alveolar bone. Undecalcified (60 microm thick) and decalcified (five microm thick) sections were prepared. The average extent of intrusion was 1.8 mm after four months and 4.2 mm after seven months. The root apices of the intruded molars penetrated into the nasal cavity. Remodeled bone around the intruded molar toots was rich in woven bone on the buccal side, whereas that on the palatal side was rich in lamellar bone. Nasal floor membrane and a thin layer of newly formed bone, which lifted intranasally, covered the intruded molar root. Root resorption partly reached into the dentine without the formation of reparative cementum, and little or no serious pathological changes were seen in the pulp of the intruded molars. SAS effectively intruded maxillary molars, but some moderate root resorption was observed.

Animals↗

Surgical-restorative treatment of bleaching-related external root resorption.

Three teeth in 2 patients were treated after intracoronal bleaching with 30% hydrogen peroxide had resulted in external root resorption. An attempt to treat one tooth by placing an intracoronal dressing with calcium hydroxide had failed. The resorption defects were exposed surgically by reducing and re-contouring the alveolar crest. The restorations were made during the surgical procedure, with a light-cured composite in one case and with amalgam in the other, and were of compromised quality due to the difficulty of control. One year follow-up examinations revealed periodontal complications in both cases, in the form of a further resorption of the alveolar crest and gingival edema. These sequelae suggested that the restoration of bleaching-related resorption defects should have been a secondary stage, after the surgical exposure of the defects had been completed first. For the purpose of exposing the defects, the level of the alveolar crest should be reduced enough to secure a biological width from the restorations.

Adult↗

A comparison of iliac marrow and biodegradable ceramic in periodontal defects.

Defects were created in the tooth-supporting bone of six beagle dogs. Biodegradable tricalcium phosphate was compared to cancellous marrow as a treatment method. The findings indicated that ankylosis and resorption of the tooth can occur when using marrow. The ceramic-filled defects healed slower; but the material itself was well tolerated by the tissues, initiated new bone formation, filled in the defect, and has good potential for the treatment of advanced periodontitis.

Animals↗

Dental transplants: discussion and case report.

A 21-year-old Chinese male patient presented to an urban dental clinic with a transplanted molar, which had been removed from a human cadaver. The tooth was in occlusal function for three years, stable, and without mobility. Radiographs of the tooth showed root resorption and apparent ankylosis. Individual transplantation of human teeth has been considered surgical dental treatment of an empirical nature for centuries. Two types of human tooth transplantation are usually considered in the dental literature. An allotransplantation or allograft is a transplantation of tissue (tooth) between different individuals of identical species. An autotransplantation or autograft is a transplantation of tissue within the same individual (obviously within the same species). Replacement of an avulsed tooth, while technically an autograft is considered a replantation, rather than a transplant. Tooth transplantations in the late 20th century are usually performed in developing third world countries, where patient dental education is minimal, and the cost of more technology based forms of tooth replacement (prosthodontics, synthetic implants) are economically prohibitive. Transplantation of permanent teeth is rarely seen in the United States in the 1990's due to the use of titanium implants, although pediatric, adolescent, and disabled patients, especially those with limited incomes, could benefit from the re-introduction of dental transplants.

Adult↗

Unusual cervical resorption after reinjury.

The root canal of a maxillary central incisor apparently completely calcified after an injury. Eight years later, this tooth was injured again and massive resorption developed. The resorption began as an unusual pattern of cervical destruction, and ultimately the entire root apparently was destroyed. However, the tooth was still serving satisfactorily without other symptoms seven years after the reinjury--15 years after the original injury. Calcification of the pulp space can develop in a tooth and the root structure can be resorbed in a tooth after an injury. Therefore a similar stimulus can produce opposite responses, in this instance in the same tooth at different times. Luxation of teeth is a treatable injury, and replantation of luxated teeth is an acceptable technique that can result in long-term retention of the replanted tooth. Replantation of the patient's own tooth is usually preferred to artificial replacement of the luxated tooth at the time of injury. Interceptive endodontic care for a tooth that has been traumatized and in which the pulp space appears on the radiograph to be calcifying is probably best for the patient.

Adolescent↗

Attachment to and phagocytosis of mineral by alveolar bone osteoclasts.

The mechanisms by which the osteoclast attaches to and resorbs bone are not fully understood. Morphologic techniques have primarily been used to examine these mechanisms, but many studies have been based on decalcified material. In this study, the attachment of the osteoclast to alveolar bone and its relationship to the mineral component during the active resorption associated with tooth eruption in the rat was examined using transmission electron microscopy and techniques designed to minimize demineralization effects during processing. Large conglomerates of bone mineral were found within both the ruffled border and the vacuoles adjacent to this area. These deposits were clearly more extensive than the isolated mineral fragments described in other sites by previous investigators. Examination of demineralized sections showed that collagen was largely absent within the ruffled border, and not present within vacuoles. These observations suggest that phagocytosis of bone mineral may supplement its extracellular dissolution in situations associated with rapid bone turnover, such as tooth eruption. Two types of clear zone attachment to mineral were also observed, permitting further speculation on the mechanism by which osteoclasts attach to and move along the bone surface.

Animals↗

Neoplasia masquerading as periapical infection.

Seven examples of neoplasia which presented as periapical radiolucencies are described. These were all initially treated for presumed periapical infection. The atypical features that should alert dentists to the possibility of a tumour presenting in this manner are: a vital tooth with minimal caries, root resorption and an irregular radiolucent outline, tooth mobility in the absence of generalised periodontal disease, regional nerve anaesthesia, and failure to respond to good endodontic therapy. All material removed at the time of apical surgery must be examined histologically to prevent neoplasia being overlooked.

Adolescent↗

Influence of enamel matrix derivative (Emdogain) and sodium fluoride on the healing process in delayed tooth replantation: histologic and histometric analysis in rats.

Although it has already been shown that enamel matrix derivative (Emdogain) promotes periodontal regeneration in the treatment of intrabony periodontal defects, there is little information concerning its regenerative capacity in cases of delayed tooth replantation. To evaluate the alterations in the periodontal healing of replanted teeth after use of Emdogain, the central incisors of 24 Wistar rats (Rattus norvegicus albinus) were extracted and left on the bench for 6 h. Thereafter, the dental papilla and the enamel organ of each tooth were sectioned for pulp removal by a retrograde way and the canal was irrigated with 1% sodium hypochlorite. The teeth were assigned to two groups: in group I, root surface was treated with 1% sodium hypochlorite for 10 min (changing the solution every 5 min), rinsed with saline for 10 min and immersed in 2% acidulated-phosphate sodium fluoride for 10 min; in group II, root surfaces were treated in the same way as described above, except for the application of Emdogain instead of sodium fluoride. The teeth were filled with calcium hydroxide (in group II right before Emdogain was applied) and replanted. All animals received antibiotic therapy. The rats were killed by anesthetic overdose 10 and 60 days after replantation. The pieces containing the replanted teeth were removed, fixated, decalcified and paraffin-embedded. Semi-serial 6-microm-thick sections were obtained and stained with hematoxylin and eosin for histologic and histometric analyses. The use of 2% acidulated-phosphate sodium fluoride provided more areas of replacement resorption. The use of Emdogain resulted in more areas of ankylosis and was therefore not able to avoid dentoalveolar ankylosis. It may be concluded that neither 2% acidulated-phosphate sodium fluoride nor Emdogain were able to prevent root resorption in delayed tooth replantation in rats.

Animals↗