Post-permanent dentition in the premolar region.
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Adolescent↗
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Results for “TOOTH CALCIFICATION”
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The microradiographic features of dentine caries. Observations on 200 lesions.
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Dental Caries↗
Use of calcium hydroxide for apical barrier formation and healing in non-vital immature permanent teeth: a review.
OBJECTIVE: To review the use of calcium hydroxide for induction of apical barrier formation and healing in immature permanent teeth. INTRODUCTION: Pulp necrosis is a frequent complication of dental trauma in immature permanent teeth. Endodontic treatment of these teeth is often complicated. The walls of the root canals are frequently divergent and the apices immature, making debridement and obturation difficult. The aim of treatment is induction of apical healing which may be defined as apical closure through formation of mineralised tissue and repair of the periapical tissues. Calcium hydroxide is the material of choice for apical barrier formation and healing. RESULTS: The use of calcium hydroxide for apical barrier formation is successful in 74-100% of cases irrespective of the proprietary brand used. The average length of time for apical barrier formation is approximately 5 to 20 months. Control of infection and adequate cleaning of the root canal are very important for apical healing. CONCLUSIONS: While the success rate of apical barrier formation using calcium hydroxide is high, long-term follow-up of these teeth is necessary. Problems such as failure to control infection, recurrence of infection and cervical root fracture may occur. The latter is more frequent in immature luxated teeth with the least root development.
Bacterial Infections↗
Late third molar genesis: its significance in orthodontic treatment.
(1) Third molar genesis may occur up to the age of sixteen years, although the possibility of their appearance after the age of twelve years is reduced. (2) When third molar genesis is delayed beyond the age of ten years, the possibility of all four third molars developing is reduced by about fifty percent. (3) The intraindividual variability in stage of development of third molars increase when genesis is delayed beyond ten years of age. (4) There is no significant difference in size of early and late developing third molars.
Adolescent↗
Development and characterization of an SV40 immortalized porcine ameloblast-like cell line.
Enamel is secreted as a protein matrix by the ameloblasts. These same cells then control the maturation of the enamel matrix, secreting proteinases that hydrolyze proteins as mineralization progresses, until mature enamel containing less than 1% protein by weight remains. Further understanding of the factors that control ameloblast function and differentiation requires an in vitro cell culture system. In this study, we report immortalization of enamel organ epithelial cells and the selection of a cell line with characteristics of ameloblasts. Porcine enamel organ cells were dissected from unerupted porcine molars, cultured in serum-free medium, and passaged twice. These cells were transfected with an origin-of-replication defective SV40 plasmid by calcium phosphate precipitation, and a cell line with mRNA expression characteristic of ameloblasts was cloned. This cell line (PABSo-E) expressed mRNA for amelogenin, matrix metalloproteinase-20 (enamelysin), and enamel matrix serine proteinase 1 (EMSP1), but not ameloblastin. PABSo-E cells have been passaged more than 55 times, while continuing to maintain characteristics of ameloblasts. These cells will be useful for future studies of ameloblast function.
Ameloblasts↗
Enamel hypomineralization of permanent first molars: a morphological study and survey of possible aetiological factors.
OBJECTIVES: The aim of this study was to investigate the morphological appearance of severe hypomineralized enamel of permanent first molars by means of polarized light microscopy, and to estimate the possible time, severity and longevity of the insult. Furthermore, the aim was to survey some commonly implicated aetiological factors in order to gain knowledge about possible pathogenesis of the enamel disturbances which could be compared with future epidemiological studies. SAMPLE AND METHODS: Seventy-three teeth, which had been extracted due to severe hypomineralizations of the enamel, were collected and serially cut longitudinally in a bucco-lingual direction. The sections were examined in polarized light, dry and embedded in water. The children were also examined with respect to the demarcated opacities of other permanent teeth than those that were extracted. The parents were asked about their health during the mother's pregnancy, the time of gestation, birth weight and any complications. They were also asked about the child's health during the first 2 years of its life, the length of time of breast-feeding and also about fluoride supplements. RESULTS: The hypomineralized areas extended cervically from the cusps, comprising about half of the buccal and lingual sides. The cervical borders to normal enamel were well defined and mainly followed the lines of Hunter-Schreger. The hypomineralized zones were covered by thin well-mineralized enamel. The majority of the children had demarcated opacities of all their first molars and also of some permanent incisors. No obvious correlation to the anamnestic data could be found. CONCLUSIONS: The hypomineralized enamel in the investigated teeth demonstrated areas of porosity of varying degrees. The yellow/brown defects were more porous than the white-cream and extended through the whole enamel layer, while the white-cream opacities were situated in the inner parts of the enamel. There had probably been an interacting disturbance of short duration of systemic origin of the activity of the ameloblast during the first 2 years of the child's life, resulting in chronological dispersed hypomineralized demarcated opacities in the developing teeth.
Adolescent↗
Fine structure of the cap enameloid and of the dental epithelial cells during enameloid mineralisation and early maturation stages in the tilapia, a teleost.
Morphological features of the cap enameloid and dental epithelial cells were investigated by light and transmission electron microscopy during the various stages of enameloid mineralisation and early maturation in the tilapia. The pattern of mineralisation along collagen fibrils in the enameloid differed from that in the dentine. Many matrix vesicles were found in the predentine and in the enameloid, suggesting that they may be involved in the initial mineralisation in both regions. Most of the organic matrix disappeared from the cap enameloid during mineralisation and maturation. The disappearance of the organic matrix could be divided into 2 stages. Initially a fine network-like matrix, which probably consisted of glycosaminoglycans and extended between collagen fibrils, began to disappear. At the same time, fine crystallites and electron-dense, fine granular material covered the collagen fibrils as mineralisation of the enameloid began. In the second stage, the maturation of the enameloid, the collagen fibrils degenerated completely and disappeared from the cap enameloid, being replaced by large numbers of large crystals. At the mineralisation stage, the numbers of lysosomal bodies tended to increase in the inner dental epithelial (IDE) cells, which contained a well developed Golgi apparatus and rough endoplasmic reticulum (rER). At the early stage of maturation, a ruffled border was noted at the distal ends of the IDE cells, which contained many mitochondria and lysosomal bodies, but less rER. These features suggest that the cells actively absorb the organic matrix, which includes collagen fibrils, in the cap enameloid. The outer dental epithelial (ODE) cells were translucent cells that contained well developed labyrinthine canalicular spaces from the onset of the mineralisation stage to the middle stage of maturation. The IDE and ODE cells were clearly involved in the mineralisation of the cap enameloid at the mineralisation and maturation stages.
Animals↗
The fate of developing teeth in mandibular lengthening by distraction: an experimental study.
Purpose: The purpose of this study was to observe developing teeth in a lengthened mandible after distraction. Material: Ten mongrel dogs with deciduous dentitions were used. Methods: A corticotomy was carefully made around a tooth bud and the external distractor (Orthofix M-100((R))) was connected. After a 5-day latent period, distraction was started at a rate of 0.75 mm per day for 10 consecutive days. Then, the lower jaw was stabilized by an external fixation to allow ossification. While the operation was performed on the left side (Distraction group), the contralateral side was studied for comparison (Control). In addition, a corticotomy, artificial fracture and external fixation were carried out to confirm the influence of the operation (Fracture group). Then macroscopic, radiographic and histological evaluations were carried out. Results: In the Distraction group, the space between the wall of the dental follicle and the crown expanded as distraction began. The end of the calcified root became wider and irregular during the distraction period, and finally, the apex closed. In the Fracture group, the teeth erupted although slight alterations of the root shape were observed in association with the operation period. Conclusion: The root became irregular, but the teeth erupted within the distraction area. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.
Journal Article↗
Deletion of dentin matrix protein-1 leads to a partial failure of maturation of predentin into dentin, hypomineralization, and expanded cavities of pulp and root canal during postnatal tooth development.
The dentin matrix protein-1 (DMP-1) gene is identified in odontoblasts during both embryonic and postnatal development. In vitro study suggests that this noncollagen acidic phosphoprotein plays a role in mineralization. However, deletion of the Dmp-1 gene has little effect on tooth development during embryogenesis. To address the role of DMP-1 in tooth during postnatal development, we analyzed changes of dentinogenesis in Dmp-1 null mice from 3 days after birth to 1 year. Here we show that Dmp-1 null mice postnatally develop a profound tooth phenotype characterized by a partial failure of maturation of predentin into dentin, enlarged pulp chambers, increased width of predentin zone with reduced dentin wall, and hypomineralization. The tooth phenotype of these mice is strikingly similar to that in dentin sialophosphoprotein (Dspp) null mice and shares some features of the human disease dentinogenesis imperfecta III. We have also demonstrated that DSPP levels are reduced in Dmp-1 null mice, suggesting that DSPP is probably regulated by DMP-1 during dentinogenesis. Finally, we show the absence or delayed development of the third molar in Dmp-1 null mice, which is probably secondary to defects in Dmp-1 null bone. Taken together, these studies suggest that DMP-1 is essential for later dentinogenesis during postnatal development.
Animals↗
Type X collagen in human enamel development: a possible role in mineralization.
Although type X collagen is one of the key molecules in endochondral ossification, no data are available on whether it is present in dental structures when mineralization is proceeding. We therefore monitored the appearance of type X collagen in tooth germs of human samples ranging in gestational age from 17-week-old fetuses to 9-week-old newborn. Using immunohistochemistry, ELISA techniques, and Western blotting, we show that type X collagen is present in human tooth germ during enamel maturation. Intense immunohistochemical staining for collagen type X was observed in the enamel and in the apical parts of secretory ameloblast at the bell stage when the dentine and enamel matrix were already under formation. The odontoblasts, the dentine, and the pulp were not stained. In the early (9-week) postnatal stage, the staining for collagen type X in the enamel matrix was diminished, and only a very weak signal could be detected in the secretory ameloblasts. A positive reaction for collagen type X was also observed in ELISA assay of extracts obtained from human embryonic enamel and hypertrophic cartilage samples. The Western blot analysis of the enamel demonstrated that size of the molecule detected by MoAb X53 is characteristic of the type X collagen. This correlates well with our immunohistochemical findings. Based on these data, we propose that type X collagen is one of the candidate molecules present in the enamel matrix that might be involved in mineralization of the enamel.
Ameloblasts↗
Emergence of permanent teeth and dental age in a series of Finns.
The emergence of permanent teeth was studied in 187 Finnish children who had longitudinal records of the emergence of all permanent teeth except third molars. Exact emergence dates were known for about one third of the teeth. Emergence ages of the remaining teeth were based on their presence and absence at clinical examinations. We calculated ages at clinical eruption of permanent teeth and tooth counts at half year intervals. Ages corresponding to counts of permanent teeth from 1 to 27 are also given. The schedules presented, which slow means, standard deviations, and percentage distributions, are expected to serve as useful references in clinical dentistry, pediatrics, forensics, and research. The mandibular central incisor emerged before the first molar of the same jaw in 68% of the children. A change in the emergence order of these teeth in Finns seems to have occurred in the 1960s. A visual comparison of dental maturity curves based on tooth counts with curves based on tooth mineralization in a previous Finnish radiographic study showed that the mean curves had roughly the same form, whereas the forms of standard deviation curves differed distinctly. It appears that the two methods to assess dental maturity are not interchangeable in practice. Tooth counts can be used in maturity estimations up to about 13 years of age, whereas the radiographic method works best to about 11 years.
Adolescent↗
Third molar impaction--a consequence of late M3 mineralization and early physical maturity.
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Adolescent↗
Dental maturation in subjects with extreme vertical facial types.
The purpose of this research was to investigate whether there is a difference in dental maturation between skeletal open bite and skeletal deep bite subjects of the same chronological age. The material consisted of 40 lateral headfilms and 40 panoramic radiographs of 20 male and 20 female white subjects, with a mean chronological age of 9 years and 2 months (range: 7 years 6 months to 10 years 11 months). These subjects were selected on the basis of lower anterior face height as a percentage of total face height and on the amount of open or deep-bite from a total sample of 400 subjects. The persons exhibiting the most extreme values at both ends of the distribution were selected to create two groups with 20 subjects in each (10 males and 10 females). Thus, the groups represented subjects with either a large lower anterior face height associated with an open bite or a small lower anterior face height associated with a deep bite. A double blind determination of dental maturation, expressed by dental age, for each subject was performed on the panoramic radiographs using the system of Demirjian et al. (1973). A covariance analysis was used to eliminate variability introduced by the large age range of the sample. The skeletal open bite and deep bite groups presented mean dental ages of 120.48 and 114.00 months, respectively. Statistical analysis demonstrated that this difference was statistically significant at P < 0.05. Therefore, it seems that skeletal open bite subjects presented a slight tendency to have an advanced dental maturation, expressed by dental age, as compared with skeletal deep bite subjects.
Analysis of Variance↗
Prediction of lower third molar impaction from the frontal cephalometric projection.
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Adolescent↗
A scanning electron and confocal laser microscope investigation of tetracycline-affected human dentine.
Because of the well reported dental side-effects of tetracycline administration, the drug should not be administered to children. However, it and its derivatives are often administered over a prolonged period for treatment of acne in young adults. Dental side effects are also noticed in these patients. The aim of this study was to examine with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) the root dentine of a tooth from a young adult affected by tetracycline therapy. The palatal root of an upper third molar, demonstrating distinct areas of tetracycline staining, was removed from the crown and sectioned longitudinally to produce two samples. The pulp tissue was peeled off the dentine and any remaining non-mineralized tissues were removed with sodium hypochlorite. One sample was prepared for SEM and the other as a ground section which was examined with a CLSM. It was demonstrated by SEM that the mineralizing front of unaffected dentine was of a normal calcospherite appearance; in contrast, the mineralizing front of the tetracycline-affected dentine was devoid of calcospherite formation and many surface defects were apparent. In addition, the number of dentinal tubules associated with the defects was reduced. It was shown by CLSM that tetracycline bands were made up of numerous smaller bands and that peritubular dentine not associated with fluorescent bands had incorporated tetracycline. The CLSM examination of the mineralization front of the affected dentine revealed that fluorescence of dentine was restricted to the peritubular dentine. The results confirm that dentine mineralization is affected by systemic tetracycline therapy and that tetracycline can be incorporated into peritubular dentine after mineralization of the primary dentine matrix.
Adult↗
Influence of different endodontic methods of treatment upon the process of apical closure of immature pulpless human teeth and the structure of the newly formed calcified tissue in apical opening.
A description is given of the pathohistological structure of the calcified tissue in the apical opening of four extracted immature pulpless human teeth treated by various endodontic methods. It is concluded that in the tooth treated by mortal extirpation there was neither histological healing nor any tendency for further apex formation. In both the tooth where vital extirpation was performed and in one of the teeth treated as apical periodontitis, the apices were formed from conglomerates of different calcified tissues, identical to the tissue which was formed under comparable conditions in experimental dogs. In the fourth human tooth also treated as apical periodontitis after treatment the apical opening closed with irregular dentine tissue. In this study consideration was given to the problem of the origin of the odontoblasts which co-exist with the hard destructive process present in some pulpless teeth. It is concluded that in the case presented in this study the irregular dentine was formed by the same odontoblasts which took part in the process of normal odontogenesis. This fact, should be respected in the course of endodontic treatment of immature pulpless teeth.
Animals↗
Analysis of the surface characteristics and mineralization status of feline teeth using scanning electron microscopy.
External resorption of teeth by odontoclasts is a common condition of unknown origin affecting domestic cats. Odontoclastic resorptive lesions involve the enamel cementum junction (ECJ, cervix) and root surface, leading to extensive loss of enamel, dentine and cementum. This study was undertaken in order to determine whether features of the surface anatomy and mineralization of feline teeth could explain why odontoclastic resorptive lesions are so prevalent in this species. Backscattered electron scanning electron microscopy was used to study enamel, cementum and dentine in non-resorbed, undemineralized teeth from adult cats. Analysis of the ECJ revealed thin enamel and cementum and exposed dentine at this site. Furthermore, enamel mineralization decreased from the crown tip to the ECJ, and dentine mineralization was lowest at the ECJ and cervical root. Analysis of cementum revealed variations in the organization and composition of fibres between the cervical, mid- and apical root although no significant differences in mineralization of cementum were detected between different regions of the root. Reparative patches associated with resorption of cementum by odontoclasts and repair by cementoblasts were present on the root surface. In conclusion, results suggest that the ECJ and cervical dentine could be at a greater risk of destruction by odontoclasts compared with other regions of the tooth. The relationship of these features to the development and progression of resorption now requires further examination.
Animals↗
Observations of root surfaces from patients with early-onset periodontitis and leukocyte adhesion deficiency.
The purpose of this investigation was to report observations of the root surfaces of teeth from 2 siblings with leukocyte adhesion deficiency (LAD). In previous publications, the clinical, radiographic and immunologic findings in the family were presented. 38 permanent teeth from the 2 siblings were prepared for microscopic examination, 11 for light microscopy (LM), and 27 for scanning electron microscopy (SEM). In addition, 8 healthy teeth obtained from 2 patients requiring extractions for orthodontic treatment served as controls. LM observations on healthy teeth revealed cementum with normal structural appearance which exhibited a mosaic or mogul-like pattern with SEM. In LAD specimens, cementum apical to the dentogingival junction exhibited resorption lacunae and areas of poor structural definition characterized by aplasia and hypoplasia (hypomineralization). Areas of hypoplasia presented as distinct irregular surfaces with a pebbly or globular-like appearance. Alteration in cementum formation and maturation may play a role in the etiology of early-onset periodontitis.
Adolescent↗