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PubMed1993

Calcospherites in rabbit incisor predentin.

Calcospherites from the lower incisor dentin of rabbits were investigated by scanning and transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and electron diffraction analyses. In the labial predentin, globular calcospherites of 8-31 microns were present at the root apex, decreasing in size toward the incisal region. The calcospherites at the intermediate region were of mulberry- as well as of spindle-shape of 1.5-4 microns diameter. The incisal pulp horn contained micro-calcospherites of 0.3-0.6 micron in diameter. In the lingual predentin, small granular calcospherites of 1.8-3 microns were present at the root apex, increasing in size toward the intermediate region. Ultrathin sections of globular calcospherites showed bundles of collagen fibrils at the root apex of the labial predentin. The diameters of individual bundles ranged from 1.2-3.4 microns. The width of the fibrils in the bundles was approximately 120-170 nm. Bundles of collagen fibrils were not found in the lingual predentin. Crystals of calcospherites were identified as apatite by electron diffraction. Those at the intermediate region showed preferred orientation of the c-axis. TEM-EDS analyses indicated that Ca and P were the major elements, with small amounts of Mg. The Mg/Ca molar ratios decreased from the root apex to the incisal pulp horn. Ca peak intensities increased from the root apex to the incisal region.

Animals↗
PubMedDate not supplied

The mineral composition and enamel ultrastructure of hypocalcified amelogenesis imperfecta.

Hypocalcified amelogenesis imperfecta is characterized clinically by a yellow-brown colored enamel that is prone to severe attrition, often leading to rapid destruction of the crown. While the enamel is thought to be poorly mineralized few studies have evaluated the mineral content, or the histological or microradiographic features of this specific AI type. The purpose of this investigation was to examine teeth affected with autosomal dominant hypocalcified AI histologically using light microscopy (LM), scanning electron microscopy (SEM), and to evaluate the degree of enamel mineralization chemically and with microradiography. Four AI teeth were obtained from an affected individual for comparison with age-matched teeth from normal healthy individuals. Thin sections approximately 100 microns were cut with a diamond disc for examination by LM and microradiography. Using SEM, fractured enamel samples were examined either untreated or after removal of organic material using NaOCl or urea. Normal and AI enamel particles were dissected from thin sections to evaluate the mineral per volume and carbonate content. The enamel was not uniformly affected in all areas of the teeth with the lingual surfaces of the mandibular central incisors appearing clinically and histologically normal. The affected enamel was porous and appeared opaque with LM. Both SEM and LM showed the enamel to be prismatic with relatively normal prism morphology. However, the enamel crystallites were rough and granular compared with those of normal enamel. Extraction to remove organic material did not change the appearance of the crystallites indicating their granular appearance was due to mineral and not residual organic material such as enamel protein. Microradiography showed the enamel was less radiodense and therefore poorly mineralized compared with normal enamel. This was confirmed by chemical determination of the mineral per volume, which showed some areas of the AI enamel had as much as 30% less mineral compared with normal enamel. The carbonate content was found to be similar in AI and normal enamel. Hypocalcified AI is associated with decreased mineralization as well as ultrastructural defects in the crystallite structure. The combined histological and biochemical features of hypocalcified AI seen in this investigation indicate that this AI type is distinctly different from the hypoplastic and hypomaturation AI types.

Amelogenesis Imperfecta↗
PubMed1996

Dentin formation after corticosteroid treatment. A clinical study and an experimental study on rats.

The overall aim of this series of studies was to determine whether the extensive narrowing of the dental pulp chamber seen in dental radiographs of patients with end stage renal disease was related to the method of treatment of the renal disease. The treatments studied were immunosuppression, renal transplantation and hemodialysis. A strong correlation was found between narrowing of the dental pulp chamber and renal transplantation. In the immunosuppression group and in the renal transplantation group, the patients received immunosuppressive drugs, mainly corticosteroids and azathioprine. Significantly higher doses of corticosteroids had been given to patients showing narrowing of the dental pulp chamber than to patients without such narrowing. The total plasma clearance of the corticosteroids received was measured among transplanted patients. The total plasma clearance was lower in patients with narrowing of the dental pulp chamber than in patients without narrowing. The morphology of the corticosteroid induced dentin in premolars from five deceased patients who had received one or more renal transplants each was compared with that in extracted teeth from five healthy individuals. The results of this study showed that dentin formation after high dose corticosteroid treatment in humans seems to start with a widening of the predentin zone, followed by extensive mineralisation causing substantial reduction of the dental pulp chamber within a few years after the start of treatment. In an experimental study on rats, it was shown that intravenous administration of high doses of corticosteroids induced dentin formation along the pulp chamber walls in the molars. Energy dispersive X-ray microanalysis was used for estimation of the calcium and phosphorus content of the dentin in rat teeth. The calcium and phosphorus composition of the corticosteroid induced dentin was found to be equal to that of normal dentin in control rat molars, which might imply that the mineralisation process was not affected by the corticosteroid treatment and thus the quality of the corticosteroid induced dentin might be equal to normal dentin regarding the calcium and phosphorus composition. In a scanning microscopy study of the morphology of the corticosteroid induced dentin in rat incisors, it was found to be equal to that of normally formed dentin.

Adolescent↗
PubMed1996

A photographic study of developmental defects of enamel in Brazilian school children.

The aims of this study were, to record developmental enamel in three areas of Brazil with a range of fluoride concentrations in their drinking water and to consider the association between clinical and photographic methods of recording enamel defects. A total of 457 subjects were examined from areas with less than 0.01, 0.7 and 2-3 ppm F in their drinking water. From the photographs, the prevalences of subjects with TF scores of one or more for the upper permanent central incisors were 7 per cent, 52 per cent and 92 per cent respectively for the three areas. The prevalence of demarcated opacities decreased with increasing fluoride levels in the drinking water (p < 0.008). There was substantial agreement between the Thylstrup Fejerskov (TF) scores using clinical and photographic methods (kappa = 0.63). However, prevalences of TF scores of one or more were higher using the photographic (44.9 percent) than clinical (41.4 percent) method (p < 0.01). The results of this study were compared with one undertaken in the United Kingdom and Ireland which also used the same photographic method. Although the prevalences of TF scores of one or more were similar in the areas with near 'optimal' levels of fluoride in the drinking water, in the groups with levels of fluoride less than 0.1 ppm the prevalence of subjects with TF scores of one or more was higher in the United Kingdom population than in Brazil. This study demonstrates the utility of photographic methods of collecting information on enamel opacities over a wide range of fluoride exposure. Results suggest that for the groups from areas with low levels of fluoride in the drinking water the overall fluoride exposure of the UK children was greater than the Brazilian.

Age Factors↗
PubMedDate not supplied

Developmental dental changes in isolated cleft lip and palate.

Isolated cleft lip and/or palate, CL(P), may be associated with multiple changes in the developing dentition. To test the hypothesis that permanent tooth formation is delayed in patients with CL(P), dental maturity was assessed from panoramic radiographs. The dental maturity ratio (DMR, dental age divided by chronological age) of a group of CL(P) patients (23 girls, 30 boys) was compared with matched control subjects (38 girls, 41 boys). The mean DMR in cleft boys (0.97 +/- 0.01) was significantly lower than in control boys (1.06 +/- 0.01), P < 0.05. The mean DMR in cleft boys was lower than in cleft girls (1.02 +/- 0.02), with a tendency toward statistical significance. No significant difference in DMR was found between the cleft versus control girls, or between the control girls and boys. Among cleft boys, the prevalence of dental age delay was 67% (20/30), with a mean delay of 0.6 +/- 0.4 years. These results suggested that CL(P) may be associated with delay in permanent tooth formation.

Analysis of Variance↗
PubMed1977

Molar polymorphisms and the timing of dentition mineralization.

The chronological age, skeletal age, and morphological age at the time of mineralization of 14 stages of the permanent teeth of 121 boys and 111 girls of the serial experimental sample of the Burlington Growth Centre were contrasted according to whether or not the children had 4- or 5-cusped mandibular permanent first molars, and whether or not they had agenesis of one or more third molars. In the boys with 4-cusped mandibular first molars, the mineralization of the teeth occurred at significantly earlier chronological and skeletal ages when they were significantly shorter in stature. Tooth mineralization was not consistently earlier in the girls with 4-cusped molars, but these girls tended to be taller and heavier than those with 5-cusped molars. In contrast, in both sexes with agenesis of third molars, the mineralization of the teeth was significantly delayed according to chronological, skeletal and morphological evaluation. The change in timing of mineralization was greatest for the second premolars and second molars, and least for the first molars.

Age Factors↗
PubMed1997

The biomimetics of enamel: a paradigm for organized biomaterials synthesis.

The formation of enamel takes place through a sequence of processes that can be mimicked in inorganic materials chemistry. This chapter describes the generic features of enamel biomineralization in terms of a house-building analogy. Four stages are identified: supramolecular preorganization and spatial patterning; interfacial molecular recognition in inorganic nucleation; vectorial crystallization; and pattern evolution and hierarchy. Each of these concepts can be translated into synthetic approaches to the formation of inorganic materials with organized architectures. An example of applying this biomimetic paradigm is described. Supersaturated water-in-oil microemulsions have been used to synthesize microskeletal calcium phosphates by controlled nucleation and vectorial growth in constrained reaction environments. The results of these preliminary studies suggest that biomimetic concepts could be useful in the fabrication of biomaterial implants with controlled porosity and microstructure.

Amelogenesis↗
PubMed1995

Assessment of puberty growth spurt in boys and girls--a dental radiographic method.

The first radiographic appearance of adductor sesamoid bone of thumb is considered reliable and is the most commonly used indicator of puberty growth spurt. The purpose of this study was to find out whether the tooth mineralization stage/stages were as reliable an indicator of puberty growth spurt as the adductor sesamoid bone. Puberty assessment has its necessary application in diagnosis, treatment planning of various malocclusions and in medico legal cases. The results indicated that a close relationship existed between tooth mineralization Stage G and appearance of the sesamoid bone. Hence it can be used in dentistry as an indicator for onset of puberty growth spurt via periapical or panoramic radiographs. The result of this study were not applicable to boys as the apical closure of these teeth had already occurred at the time of early radiographic appearance of the adductor sesamoid bone.

Adolescent↗
PubMed1995

Ultrastructural study of tooth enamel with amelogenesis imperfecta in AI-nephrocalcinosis syndrome.

This paper describes the ultrastructure of the affected enamel and the clinical features in two siblings with the syndrome of nephrocalcinosis and amelogenesis imperfecta. Nephrocalcinosis was diagnosed by intravenous pyelography, and confirmed by ultrasonography and CT scan. Amelogenesis imperfecta AI was diagnosed clinically and histologically. Light microscopy showed that the affected enamel surfaces were rough and the enamel was hypoplastic and mainly positively birefringent. Scanning electron microscopy revealed a rough and extensively cracked enamel surface covered with oval shaped blister-like protrusions. TEM showed porous enamel consisting of loosely packed and randomly oriented thin ribbon-like crystals with little or no prismatic structure. Observations showed that hypoplasia together with hypocalcification and/or hypomaturation defects were present in the same tooth, indicating the possibility of an abnormality in interstitial matrix, leading to dystrophic calcification in the kidney and abnormal tooth enamel formation, or alternatively an involvement of two separate but closely linked genes.

Adolescent↗
PubMed1991

Radiographic observations on root resorption in the primary dentition.

In order to construct standardized charts for root resorption in the primary dentition of Japanese children, we investigated the stages of resorption (1/4, 1/2 and 3/4 of the root) based on the criterion of Fanning, et al. using 11,167 panoramic radiographs (5,759 of boys and 5,408 of girls). The following information was obtained. 1) The root resorption for a tooth on one side was the same as for its counterpart on the other side regardless of differences in sex or arch. 2) The average age for each root resorption stage was lower in girls than in boys regardless of differences in sex or arch. 3) The average age for each root resorption stage was lower in the mandible than in the maxilla for every tooth. 4) In the maxilla, the period between 1/4 to 3/4 resorption of the root was greater in the primary molars than in the primary anterior teeth. However, the opposite was true in the mandible. 5) Although no difference was observed between the maxilla and the mandible in the resorption period for the primary incisors and canines, the resorption time for the primary molars was greater in the maxilla than in the mandible. 6) When the relationship was observed between the resorption stages for each tooth and the calcification stages for the corresponding successional permanent tooth. a) With the exception of the maxillary and mandibular canines, the average age for 1/4 resorption of the primary root corresponded to the period between completion of the permanent crown and initial root formation of the successional permanent tooth. b) With the exception of the maxillary and mandibular canines, and the mandibular second premolars, the average age for 3/4 resorption of the primary root corresponded to the period between 1/4 and 1/2 formation of the root of the successional permanent tooth. From these results, standardized charts were constructed for the resorption of the roots of primary teeth in Japanese children. These standardized charts are useful in daily clinical practice in such areas as endodontic treatment of primary teeth and orthodontics.

Adolescent↗
PubMed1989

Tooth development in children with cleft lip and palate: a longitudinal study from birth to adolescence.

Dental maturity was assessed in 131 children with cleft lip with or without cleft palate in two age groups from panoramic X-rays using the method of Demirjian. The subjects showed a mean delay of 6 months in the age group of 3-9 years (x = 6.4 years), which decreased to 2 months in the age group of 8-14 years (x = 11.0 years). Involvement of the palate made the delay longer than in children with cleft lip only. Geographical differences between parts of Finland were also found. To study tooth development longitudinally, the timing of the beginning of calcification of one maxillary central incisor was assessed from occlusal X-rays taken between the ages of 2 and 18 months in 107 of the above mentioned 131 subjects. Using rank-order correlations, the beginning of the calcification of the maxillary central incisor weakly predicted the subjects' tooth developmental status. The correlation of dental maturity between the ages of 6 and 11 years was, however, high.

Adolescent↗
PubMed1998

Computed tomographic features of calcifying odontogenic cysts.

OBJECTIVES: To describe the CT appearances of 4 cases of the calcifying odontogenic cyst (COC) with particular reference to the effect of varying the window settings. METHODS: Conventional radiographs and CT scans of 4 calcifying odontogenic cysts were analyzed with respect to the presence of an impacted tooth, root resorption and calcification. In addition, increased attenuation by desquamated keratin was examined by varying the window settings on CT. RESULTS: All lesions were located in the maxilla and on conventional radiographs, had unilocular radiolucency with a well-defined margin. Calcifications and inclusion of an impacted tooth were seen in all cases. Root resorption was observed in two cases, but was not prominent. On CT, calcification was detected at the periphery of the lesion and/or around the impacted tooth in all cases. Varying the window setting revealed an increased attenuation area due to desquamated keratin. CONCLUSIONS: Varying the window setting on CT is useful as a means of identifying both desquamated keratin and peripheral calcification in COC.

Adolescent↗
PubMed1994

Localization of uncalcified cementum in adult rat molar roots and its relation to physiological tooth movement.

The study was designed to elucidate the effect of physiological tooth movement on cellular cementum, using the upper molar roots of 10-week-old rats. Paraffin sections stained with haematoxylin and eosin displayed two types of cellular cementum, lightly and darkly staining. The lightly stained was present on the distal half of all molar roots except the mesial root of the first molar. The alveolar bone facing the lightly stained cementum showed resorption lacunae and multinucleated osteoclasts, while the opposite bone surface was lined with osteoblasts. In contact microradiographs of undemineralized ground sections, the X-ray density of the lightly stained cementum was similar to that of the periodontal ligament and pulp, while the X-ray density of the darkly stained cementum was similar to that of alveolar bone. Tetracycline labelling lines were seen at the interface between the two types of cellular cementum as well as on surfaces of bone and cementum located mesially to the root dentine. The results suggest that the mechanical stress of tooth movement differently affects the alveolar bone and cellular cementum; the bone is resorbed whereas the cementum resists resorption and its calcification is inhibited under the compressive force of tooth movement.

Absorptiometry, Photon↗
PubMed1982

Ultrastructure of initial calcification in wound healing following pulpotomy.

Initial calcification in healing amputated tooth pulps was examined in a transmission electron microscope (TEM). The process is characterized by an abundance of extracellular matrix vesicles (0.1-0.2 micrometer in diameter) distributed between forming cells and the surface of the amputated pulp. Osmiophilic material and needle-like crystals within the vesicles was followed by disappearance of the vesicular membrane and accumulation of crystals and aggregate into calcified fronts. Ca and P were detected in these needle-like crystals by an electron probe X-ray microanalyzer. This finding suggests that the crystals were produced during the calcifying process. The healing of amputated tooth pulps is essentially similar to initial calcification events that occur in other normal and pathologic calcified tissues.

Animals↗
PubMedDate not supplied

[Successful endodontic treatment of dens in dente].

The dens in dente is a developmental variation which is thought to arise as a result of an invagination in the surface of a tooth crown before calcification has occurred. This report is a case which documents the successful non surgical endodontic treatment permanent tooth with dens in dente by periodical dressing the intracanal space with calcium hydroxide for a year and follow up after permanent filling-for one and a half years. After a sign of repair around the periapical area had occurred, the canal was filled with warm gutta percha technique. The importance of early and corrected diagnosis, the possible significance of even a small and noncarious dens in dente, and the treatment of anomaly were emphasized.

Calcium Hydroxide↗