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At least 397 records · Page 22Linked to original sources
PubMed1990

Dental developmental status of southern Chinese girls in Hong Kong.

Dental developmental status of the permanent canines, premolars and second molars were studied in one hundred and two twelve-year-old Southern Chinese girls born and brought up in Hong Kong. Eruption of these teeth were defined as gingival emergence during the clinical examination while the root development was assessed from orthopantomographs. Root resorption pattern of the primary canines and molars were also studied with the aid of the orthopantomographs. Two-thirds of girls presented with permanent dentition stage. The root resorption patterns of the primary teeth were different from their order of exfoliation. The mandibular permanent teeth were in advanced in both eruption and root development than the corresponding maxillary teeth, except the first premolars.

Asian People↗
PubMed1982

Chronology and histology of exfoliation and eruption of mandibular premolars in dogs.

Exfoliation of third deciduous mandibular premolars and their replacement by the third permanent premolars were compared in young dogs of purebred beagle and mongrel stock. Radiographic and histologic studies showed that eruption of the permanent premolar begins during the 16th postnatal week and is completed in 7 weeks. Root elongation proceeds with eruption, but fibers of the periodontal ligaments are not anchored in alveolar bone and do not attain their final orientation with respect to the long axis of the tooth until final phase of the eruptive period. These data define a predictable system in which various stages in the mechanism of eruption of noncontinuously erupting teeth may be examined experimentally. Furthermore, the observation that these processes are identical in timing and sequence in beagle and mongrel dogs suggests that less expensive, more readily available mongrel dogs can be used for these studies.

Animals↗
PubMed1994

Premature exfoliation of teeth in childhood and adolescence.

Although the premature loss of primary teeth in conjunction with early eruption may be of no clinical significance, the loss of primary or permanent teeth in the absence of trauma should not be overlooked by the clinician. Premature loss of teeth associated with systemic disease usually results from some change in the immune system or connective tissue. This chapter presented some conditions associated with loosening and/or premature loss of teeth that may be encountered in children and adolescents. The most common of these conditions appear to be hypophosphatasia and early-onset periodontitis. Other less common conditions were described to aid in forming a differential diagnosis. Other diseases that may manifest with severe oral infection, such as Wiskott-Aldrich syndrome, diabetes mellitus, or herpes zoster, could result in early tooth loss.

Acrodynia↗
PubMed1986

Laboratory studies of a family manifesting premature exfoliation of deciduous teeth.

In a previous publication, we described the clinical and radiographic findings of a family in which the children manifested premature exfoliation of the deciduous teeth. We now report for the same family the results of extensive laboratory studies performed on blood and urine, analysis of periodontal microflora, and a family pedigree. We demonstrated the presence of putative periodontal pathogens in the subgingival microflora, elevated levels of serum antibodies reacting to Bacteroides gingivalis, Capnocytophaga gingivalis, and C. sputigena in 2 of the children, and significantly suppressed monocyte chemotaxis in all 3 children. Phosphoethanolamine was found in the urine of the father and all 3 children, but not in the mother. Likewise, serum alkaline phosphatase was abnormally low for all 3 children, and was at the extreme low end of normal range for the father, but was normal for the mother. On the basis of the alkaline phosphatase and phosphoethanolamine measurements, we assigned a diagnosis of hypophosphatasia to the 3 children. Phosphoethanolamine and alkaline phosphatase were also abnormal in the paternal grandmother and her brother. The son of this brother who was deceased had a daughter manifesting premature loss of the primary teeth. The data are consistent with an autosomal dominant mode of transmission. In the light of our findings, hypoplastic cementum must be considered in the etiology of some forms of early-onset periodontitis.

Adult↗
PubMed1978

The relationship of buccal pits to caries formation and tooth loss.

It is demonstrated that in mandibular molars there is a statistically significant tendency for teeth with buccal pits to be lost premortem more frequently than teeth without buccal pits. The mandibles of a large ossuary population (ca. 1600 A.D.) are examined with regard to buccal pitting, caries formation and premortem tooth loss. A log likelihood ratio test is used to test the relationship between age and frequency of buccal pits. A G-value of 20.84 (p less than 0.025) indicates that the frequency of pits is significantly higher among individuals under ca. 18 years. It is argued that caries formation is the mechanism through which the molars are lost, given high caries frequencies that approximate pitting frequencies in their distribution.

Age Factors↗
PubMed1981

Changes in articular eminence morphology with dental function.

Measurements of mandibular fossa depth and slope of the articular eminence were obtained for human skeletal samples chosen to represent a wide spectrum of subsistence strategies and oral function: hunter-gatherers (Eskimos, Australians), American Indians dependent to a variable extent on maize agriculture, and early twentieth century American whites and blacks. In the Eskimo and Australian samples, a generalized and steady increase in fossa depth and slope was observed with increasing functional age (tooth wear) through wear level 5 (of 8), followed by a levelling off or slight decrease in fossa depth in later wear levels on the anterior teeth and sharp decrease in fossa depth in later wear levels on the molars. Although much less consistent due in part to extensive and early molar loss, patterns of variation in the remaining samples were characterized overall by a decrease in fossa depth and slope with increasing wear, especially on the molars. Further, in those samples with high incidences of posterior tooth loss, fossa depth was routinely less and the eminence more gently sloped in subsamples having experienced molar loss than in subsamples retaining all their molars. These data provide evidence that the temporomandibular joint (TMJ) undergoes continuous morphological alteration throughout adult life, and that these alterations are probably mediated by dental function. Moreover, they suggest that differences in patterning of such alterations may exist among human groups with contrasting patterns of tooth use.

Biomechanical Phenomena↗
PubMed1993

Pre- and postnatal low-level lead exposure and children's dysfunction in school.

The contributions of pre- and postnatal low-level lead exposures to the risk of learning problems were evaluated among 1923 children who were born in one Boston hospital in 1979-1980 and followed to age 8 years. In this relatively privileged group, more than 20% of the children had a mother with some formal postgraduate education. Prenatal lead exposure was estimated with a measurement of umbilical cord blood lead content, and postnatal lead exposure was approximated with measurement of lead in the dentin of an exfoliated deciduous tooth. Information about potential confounders and effect modifiers was obtained from maternal interview shortly after delivery and from a mailed questionnaire completed and returned when the child was approximately 6 years old. An assessment of each child's function in school was provided by the teacher, who completed a questionnaire near the end of the school year in which the child reached the age of 8 years. We considered a learning problem to be related to lead exposure if its adjusted prevalence increased with each loge increase in lead, and if the adjusted prevalence was elevated among children with high levels (i.e., approximating the highest decile) of umbilical cord blood lead (i.e., > or = 10 micrograms/dl) or dentin lead (i.e., > or = 5 micrograms/g). Girls with elevated umbilical cord blood lead levels were more likely than their peers to be dependent and inpersistent and to display an inflexible and inappropriate approach to tasks (defined as the "tasks" cluster). Boys with elevated umbilical cord blood lead levels were more likely than others to have difficulty with both simple directions and sequences of directions. Among girls, elevated deciduous tooth dentin lead content was associated with reading and spelling difficulties, the tasks cluster, and with "not functioning as well as peers." Elevated dentin lead levels were not overrepresented among boys with any of the assessed learning clusters. These findings are consistent with the inference that lead levels still prevalent among children (i.e., blood < 15 micrograms/dl) are associated with some learning problems in girls.

Child↗
PubMed1988

The neonatal pseudo-hydrocephalic progeroid syndrome (Wiedemann-Rautenstrauch). Report of a new patient and review of the literature.

A boy with the pseudo-hydrocephalic progeroid syndrome (McKusic 26409) is presented and compared to five previously reported children. The boy presented with major skeletal abnormalities, which receded during the first few months of life. Special investigations like studies on collagen, electron microscopy, and growth studies of fibroblasts did not contribute to our knowledge of the pathogenesis of this rare disease.

Collagen↗
PubMed2000

Development and fine structure of pharyngeal replacement teeth in juvenile zebrafish (Danio rerio) (Teleostei, Cyprinidae).

Teeth are commonly used model systems for the study of epithelial-mesenchymal interactions during organogenesis. We describe here the ultrastructural characteristics of developing pharyngeal replacement teeth in juvenile zebrafish, an increasingly important model organism for vertebrate development. Replacement teeth develop in close association with the dental organ of a functional tooth. Morphogenesis is well advanced prior to the start of cytodifferentiation. Fibrillar enameloid matrix is formed first, followed by the deposition of predentine. Initial mineralization of the enameloid proceeds quickly; maturation involves the presence of ruffled-bordered ameloblasts. Dentine mineralization is inotropic and is mediated by matrix vesicles. Woven-fibred attachment bone matrix is deposited before completion of dentine mineralization. Eruption of fully ankylosed teeth is a fast process and may involve degenerative changes in the pharyngeal epithelium. Mononucleated osteoclasts and clastic cells located in the pulp cavity intervene in tooth resorption prior to shedding. Structural differences with larval, first-generation zebrafish teeth include the presence of dentinal tubules and the absence of an electron-dense covering membrane. Part of these differences may relate to size differences of the teeth. Others, like the site of the replacement tooth bud, suggest that initiation may take place in already committed epithelium from the first initiation event in the larval stage.

Amelogenesis↗
PubMed1999

Enamel hypoplasia of primary teeth in chronic renal failure.

Chronic renal failure (CRF) in the first years of life is associated with developmental defects of enamel in the permanent dentition. We investigated if CRF also affects the primary (deciduous) dentition. Thirty-one children with CRF on conservative treatment (n = 12) or on renal replacement therapy (n = 19) underwent dental inspection. In addition, 18 CRF children provided an exfoliated deciduous tooth for microscopic examination. Enamel defects were detected in a total of 12 children (31%), either clinically or microscopically. Of the 7 children affected clinically, 6 (19% of all examined) presented localized hypoplasia of the primary canines, which was found only in 3% of healthy control children: 1 patient had generalized pitted enamel hypoplasia. By microscopy, 5 of 10 primary canines examined showed enamel hypoplasia localized exclusively in enamel formed after birth. The "birth line," a visible structure within the primary enamel, was always present, which excludes a prenatal onset of the defects. Of the 12 patients with an enamel defect, 9 had a documented onset of CRF within the first 7 weeks of life. We conclude that renal disease leading to CRF may affect enamel formation of primary teeth in early postnatal life, resulting in lesions different from those observed in the secondary dentition.

Adolescent↗
PubMed1980

Eruption of teeth into crowded position, loss of attachment, and downgrowth of subgingival plaque.

The role of crowded teeth in the etiology of attachment loss was studied in thirty teeth extracted for orthodontic reasons from eight children 12 to 13 years of age. Following extraction, the teeth were stained in a 1 percent solution of water blue and examined under the stereomicroscope. In one third of the thirty teeth, a 0.9, 2.0, and 3.5 mm. loss of attachment was observed on surfaces adjacent to which another tooth had erupted into an extremely crowded environment. On the same surfaces, subgingival plaque had grown down to the area of the cementoenamel junction. The premature loss of attachment was assumed to be mediated by collagenase derived from the regressing dental organ or from the junctional epithelium surrounding the erupting teeth. The premature downgrowth of subgingival plaque to the area of the cementoenamel junction was facilitated by the development of an irregular contact line within the interdental papilla, rather than a contact point above the papilla.

Adolescent↗