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At least 523 records · Page 29Linked to original sources
PubMed1999

Distribution of actin bundles in periodontal ligament of rat lower incisor.

The overall distribution of actin bundles in fibroblasts in the periodontal ligament (PDL) was examined in continuously growing incisors of the rat by confocal laser and thin-section electron microscopy to better understand the functional roles of PDL in mechanical support of the tooth and the mechanism of tooth eruption. The PDL around the incisor was divided mainly into two parts: the superior (non-enamel side of the tooth) and inferior (enamel side) parts. In the superior part, elongated fibroblasts ran obliquely near the alveolar bone and shifted direction nearly parallel to the tooth as they approached the tooth. Long and thin bundles of actin filaments were observed running along the long axis of the cells. In the inferior part, flattened cells were densely populated in the narrow space between the enamel epithelium and venous plexus with their long axis parallel to the tooth, and contained relatively thick actin bundles running parallel to the cell axis. Thus, different distribution patterns of fibroblasts and their actin bundles were recognized in different parts of the PDL. These observations suggest that different parts of the PDL of the rat lower incisor may have different functional significances such as force generation of tooth eruption and mechanical resistance to occlusal pressure and continuous growth.

Actins↗
PubMedDate not supplied

Eruption of a severely displaced second permanent molar following surgical removal of an odontoma.

The process of tooth eruption is very complex, and many of its factors remain unknown. Although radiographic features can provide clues into the eruptive potential of a tooth, underlying factors that affect tooth development and eruption are not as well defined, ranging from local disturbances to systemic disease. In addition, it is difficult to predict which teeth will require treatment and when the optimal time is to intervene. The purpose of this report is to illustrate the eruption potential of an impacted molar following the removal of a developing odontoma, despite its unfavorable position in the bone, complete root development, and orthodontic attachment loss.

Adolescent↗
PubMed1992

Two critical confounding factors in periodontal epidemiology.

The prevalence and severity of periodontitis is considerably lower than was previously estimated. The available epidemiological methods are based on the premise that loss of periodontal attachment is a unique sign of periodontitis. However, additional factors resulting in loss of periodontal attachment confound data obtained from modern studies. The physiological process of continuous tooth eruption results in loss of periodontal attachment over a lifetime, at an approximate rate of 0.1 mm/year. Anthropological and clinical evidence for continuous tooth eruption is reviewed. The position of the alveolar crest appears to be stable; loss of periodontal attachment occurs as the teeth erupt and less of the root is embedded in bone. Retrograde periodontitis caused by pulpal disease is a known cause of severe, localised destruction of periodontal tissues. Its signs and symptoms include periodontal pocket formation, purulent inflammatory exudates, angular bone loss, swelling and bleeding of the gingival tissues and increased tooth mobility. Anthropological, experimental and clinical evidence for retrograde periodontitis is discussed. Misdiagnosis of angular (hemiseptal), furcal and other forms of localised periodontal damage as periodontitis has probably resulted because of the inability to determine the quality of pulpal health and the assumption of a gingivitis-periodontitis continuum. New epidemiological methods need to be developed in which physiological and all pathological conditions which affect the periodontal attachment are recognised and appropriately categorised.

Confounding Factors, Epidemiologic↗
PubMed1993

The effects of cytoskeletal inhibitors on the collagen gel contraction by dog periodontal ligament fibroblasts in vitro.

Periodontal ligament fibroblasts (PLF) were incorporated into small collagen gel discs (100 microliters, dia 10.0 mm), cultured in media containing various concentrations of cytochalasin D or colchicine and the diameters of the discs then measured. Cytochalasin D (3.1-800 nM) inhibited contraction of the gel discs in a dose-dependent manner and 800 nM of cytochalasin D completely inhibited contraction. This complete inhibition was still observed when cell density in the gel was increased. Although colchicine at a concentration of 0.98-15.7 nM also inhibited the contraction in a dose-dependent manner, contraction at 50% of the control level was still observed in the presence of a high concentration (0.25 mM, 100 micrograms/ml). These results strongly indicate that actin filaments are more intimately involved in PLF-mediated collagen gel contraction than microtubules. Although it is suggested that PLF are involved in tooth eruption, earlier studies have shown that microtubule inhibitors inhibit eruption of rat incisors whereas the microfilament inhibitor, cytochalasin B, has no effect. Thus, the PLF theory alone seems insufficient to explain the mechanism of tooth eruption.

Actin Cytoskeleton↗
PubMed2003

The cell surface form of colony-stimulating factor-1 is biologically active in bone in vivo.

The specific biological function of the cell surface or membrane-bound isoform of colony-stimulating factor-1 (mCSF-1) is not well understood. To help define the role of this isoform in bone, we developed a transgenic mouse in which targeted expression of human mCSF-1 in osteoblasts was achieved under the control of the 2.4-kb rat collagen type I alpha promoter. Bone density, determined by peripheral quantitative computed tomography, was reduced 7% in mCSF-1 transgenic compared with that in wild-type mice. Histomorphometric analyses indicated that the number of osteoclasts in bone (NOc/BPm, NOc/TAR, OcS/BS) was significantly increased in transgenic mice (1.7- to 1.8-fold; P < 0.05 to P < 0.01) compared with that in wild-type animals. Interestingly, the osteoblast-restricted isoform transgene corrected the osteopetrosis seen in CSF-1-deficient op/op mice. Skeletal growth and bone density in op/op mice expressing mCSF-1 in osteoblasts were similar to those in wild-type mice and were dramatically different from those in the unmanipulated op/op animals. The op/op mice expressing mCSF-1 in bone had normal incisor and molar tooth eruption, whereas the op/op mice evidenced the expected failure of tooth eruption. These findings directly support the conclusion that mCSF-1 is functionally active in bone in vivo and is probably an important local source of CSF-1.

Animals↗
PubMed1991

Lathyrism and the half-life of collagen.

Maturation of collagen in the periodontal ligament has often been designated as the cause of tooth eruption. The fact that collagen has a high turnover rate provided some sort of proof of this hypothesis. It is well known that lathyrogens decrease eruption rate. Experiments were performed, using Wistar rats, which looked into the relationship between collagen turnover and lathyrism. The collagen turnover was established in teeth not erupting after the administration of lathyrogens. These results were compared to those obtained after having stopped eruption by the placement of a goldcrown on the lower incisors. It was found that lathyrism, and therefore collagen maturation, did not influence turnover rate. Thus the supposition, that collagen is responsible for tooth eruption, becomes doubtful.

Aminoacetonitrile↗
PubMed2001

[Exchange of dentition and its control. Overview of current knowledge and personal experience].

Physiological dentition exchange is often interfered with exogenous and endogenous factors. For this reason it must be steadily regulated. The authors present complex view on this topic based on literature studies and own experiences. The authors define fundamental principles "guided exchange", "tooth eruption" and "eruption path". Correct explication of these ideas is necessary for text understanding. Dentition exchange is considered as complex of eruption interactions of individual permanent teeth including molars. The project is based on idea that dentition exchange time is optimal for preventive interventions. At the end the authors underline the importance of global application of the above-mentioned principles on the whole child population.

Child↗
PubMed1984

Injury to developing canines as a complication of intranasal antrostomy. Report of a case.

A case is presented in which a 7-year-old boy had an intranasal antrostomy made, during which operation both developing permanent canines were injured. Despite complete resection of the roots, both canines erupted normally, supporting recent experimental studies of the eruption mechanism which suggested the importance of the tooth follicle instead of root growth as the essential mechanism for tooth eruption. Methods to prevent damage to permanent tooth germs during intranasal osteotomy are described.

Child↗
PubMed1999

Abrasion, erosion, and abfraction combined with linear enamel hypoplasia: a case report.

Linear enamel hypoplasia is a developmental disturbance of enamel resulting in clinically visible horizontal defects in enamel that are present on eruption of the tooth. Nondevelopmental lesions of the hard tissues of the tooth, including carious, abrasion, erosion, attrition, and abfraction lesions, require varying amounts of time after tooth eruption to develop. Because linear enamel hypoplasia lesions are present on eruption and are exposed to the factors responsible for abrasion, erosion, and abfraction, nondevelopmental lesions could occur within them in any combination. This report describes a patient with multiple teeth with linear enamel hypoplasia lesions containing nondevelopmental defects as well as nondevelopmental defects that occurred separately. Severe pain and a unique lesion morphology were associated with the linear enamel hypoplasia defects. Affected teeth were extracted because of advanced periodontitis and were sectioned to determine the nature of the enamel and dentin lesions.

Aged↗
PubMedDate not supplied

Infraclusion of lower primary molar with other familial dental anomalies: report of case.

Impaction of a primary tooth is a rare occurrence compared to impaction of a permanent tooth. Impaction should be differentiated from reimpaction, a condition in which an erupted tooth loses its apical movement and impaired development of the alveolar bone surrounding the tooth occurs. In dental ankylosis, the height of the alveolar process stops in the affected area, the adjoining teeth continue to move occlusally, and neighboring teeth drift. The author discusses the uncertain etiology of reimpaction. The history of a three-year-old patient is presented.

Child, Preschool↗
PubMedDate not supplied

[Measuring the distance of the wisdom teeth from the occlusal plane as forensic-odontological method for chronological age determination].

As part of an epidemiological study on tooth eruption it was attempted to define easily accessible criteria for age estimation in living human beings based on the distance of the wisdom teeth from the occlusal plane. 253 cast models of 149 female and 104 male patients were used for evaluation. Due to the great variability observed in the eruption of the wisdom teeth, only a small fraction of the total number of 10,924 cast models was suitable for investigation. Only teeth with the axis being perpendicular to the plane of occlusion during eruption according to radiological and clinical findings were included. After defining these inclusion criteria, the distance of the wisdom teeth from the plane of occlusion was determined and correlated to the age of the subjects. The results confirmed the known large variability concerning wisdom tooth eruption and did not show any reliable relation between age and distance values. Nevertheless, a remarkable finding that may be relevant for forensic odontostomatology was seen in one case where the lower wisdom teeth were taller than the occlusal plane, although the female patient was younger than 14 years. The upper molars were retained and root development was incomplete.

Adolescent↗
PubMed2005

Proteins in whole saliva during the first year of infancy.

During the first year of an infant's life, the oral environment is subject to drastic changes that coincide with the eruption of teeth. Proteins in saliva are important for protecting oral surfaces and provide receptors for bacterial adhesins. The objective of this longitudinal study was to monitor the general composition and expression of proteins in whole saliva of infants, to prove the hypothesis that expression of certain proteins changes during infant development, and might be associated with tooth eruption. The results showed a remarkable constancy in the overall pattern of salivary proteins and glycoproteins during infancy. Exceptions were the mucins and albumin. The mucins are expressed differentially, with first MUC7 and later MUC5B being predominant. Albumin, a marker of serum leakage, started to rise in whole saliva preceding tooth eruption. Thus, the expression of only few proteins appears to be changed during infant development.

Albumins↗
PubMed1997

Physical and motor development in male and female rat offspring prenatally exposed to gamma radiation.

The effects of radiation on physical and motor development of male and female rats exposed to ionizing radiation in utero were studied. Rats were exposed to three different doses of radiation (150 rad, 15 rad and 6.8 rad, considered as high, moderate and low doses of radiation respectively) on the 20th day of prenatal life. Exposure to 150 rad contributed to significantly lower body weights of both male and female rat offspring. Upper jaw tooth eruption was delayed in 150 rad treated male offspring, as well as in 15 rad and 150 rad treated female offspring. Cliff-avoidance response was delayed in 6.8 rad, 15 rad, and 150 rad treated male offspring; and 150 rad treated female offspring. Lower jaw tooth eruption, eye opening, and crawling were not affected by radiation in male or female animals. Results indicate that radiation affected the developmental parameters of both male and female rat offspring, and sex of the offspring played no role in the magnitude of radiation induced damages.

Analysis of Variance↗