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PubMedDate not supplied

Histology of alveolar bone and primary tooth roots in a case of cleidocranial dysplasia.

Cleidocranial dysplasia is commonly reported as an autosomal dominant inherited condition with defective formation of clavicles, malformation of the craniofacial bones, very slow exfoliation of the primary teeth and failure of the eruption of the permanent dentition. Lack of clinical resorption of the roots of the deciduous teeth and/or surrounding bone, lead to eruption failure of permanent teeth. Histopathological study (light and scanning electron microscopy), in a case of cleidocranial dysplasia, gives prominence to the hypothesis of abnormal remodelling of bone and cementum.

Alveolar Process↗
PubMed1986

Proton-induced X-ray emission analysis of Zn, Sr and Pb in human deciduous tooth enamel and its relationship to dental caries scores.

The absolute concentrations of these elements were obtained by calibration with the animal-bone standard of the International Atomic Energy Agency. From exfoliated deciduous incisors and canines of 193 6- and 9-year-old children living in four Finnish towns, 77 enamel samples from subjects with low and high caries (dmfs = 0 and greater than 6, respectively) were analysed. There were no statistically significant correlations between Zn and caries, or Pb and caries, but a weak positive correlation existed between Sr and caries (r = 0.341; p less than 0.001). The lead concentration in incisors (8.1 +/- 5.3 parts/10(6)) was twice as high as in canines (4.1 +/- 2.6 parts/10(6)), whereas the Sr concentration was lower (63 +/- 18 and 85 +/- 13 parts/10(6), respectively) emphasizing the importance of relating such analysis to the tooth type.

Child↗
PubMed2004

ADULT ectodermal dysplasia syndrome resulting from the missense mutation R298Q in the p63 gene.

Several ectodermal dysplasia syndromes have been shown to result from mutations in the gene that encodes the transcription factor p63. We describe an 11-year-old boy, with clinically normal parents, who had a developmental disorder that resembled EEC (ectrodactyly ectodermal dysplasia-clefting) syndrome (OMIM 604292). He had ectrodactyly and missing middle fingers bilaterally, onychodysplasia, hypodontia with missing teeth, hypohidrosis and lacrimal duct obstruction. DNA sequencing disclosed a heterozygous G-->A substitution at nucleotide 893, that converts an arginine residue (CGA) to glutamine (CAA), the mutation being designated R298Q. This mutation occurs within the DNA-binding domain of p63, and is close to many of the published EEC syndrome mutations. However, R298Q has been described once previously in a large German pedigree, not with EEC syndrome, but another ectodermal dysplasia disorder, ADULT (acro-dermato-ungual-lacrimal-tooth) syndrome (OMIM 103285). Further clinical assessment in our patient revealed that, apart from not having cleft lip and/or palate, he had an exfoliative dermatitis of his hands and feet, and some freckling on his face and shoulders. Collectively, these features support a diagnosis of ADULT syndrome. This study has identified a specific genotype-phenotype correlation in a rare ectodermal dysplasia syndrome and the findings are useful in improving genetic counselling in this family.

Base Sequence↗
PubMedDate not supplied

Zinc, lead and copper in human teeth measured by induced coupled argon plasma atomic emission spectroscopy (ICP-AES).

Inductively Coupled Argon Plasma Atomic Emission Spectroscopy (ICP-AES) has been used to determine Pb, Zn and Cu levels in 47 exfoliated human teeth (all of which required extraction for orthodontic reasons). Lead concentrations for the group were 1.7 microg (g tooth mass)(-1) to 40.5 microg (g tooth mass)(-1). with a median of 9.8 microg (g tooth mass)(-1). A median lead level in excess of the group value was found for the teeth of six lorry drivers who were included in the study. A more significant enhancement was found for the seven subjects whose age was in excess of 60 years. The median values for Zn and Cu were 123.0 and 0.6 microg (g tooth mass)(-1) respectively. Present values for tooth-Zn are lower than published data for other ethnic groups.

Adult↗
PubMedDate not supplied

Microhardness of carious deciduous dentin.

The purpose of this study was to measure the microhardness values of deciduous dentin and to compare the values as a function of position in the caries-affected layers of dentin including transparent, adjacent sound dentin, and dentin regions far from and not related to caries. Seven extracted or exfoliated deciduous anterior teeth that had dentin caries on a proximal surface were sectioned parallel to the long axis of the tooth. Ten sectioned and polished specimens were dehydrated and dried. Microhardness was measured with a Knoop indenter and correlated with wet-SEM micrographs. All data were statistically analyzed using a two-way ANOVA with subsequent Tukey-Kramer multiple comparison tests at p < 0.05. The hardness decreased from the dentinoenamel junction to the pulp chamber wall, except for the region under the caries. The hardness values of the region under the caries were significantly lower than those of other regions except for the inner region. For both the carious and sound sides, the hardness values of the inner region were significantly lower than those of the outer and middle regions. In comparing the hardness among regions in the carious and sound sides, the hardness of the outer, middle, and inner regions on the carious side was significantly lower than those in the sound side.

Analysis of Variance↗
PubMed1984

Cranial manifestations of hypophosphatasia in childhood nephrotic syndrome.

A 7-year-old boy was referred to the children's hospital because of gross oedema and tiredness. Massive proteinuria was found and the condition was diagnosed as a childhood nephrotic syndrome. Concomitantly, pathologically low levels of serum alkaline phosphatase were recorded, and this, together with generalized osteoporosis and premature synostosis of cranial sutures, led to a second diagnosis: hypophosphatasia. The patient's family history further confirmed this condition of a heritable defect of metabolism. Dental inspection revealed very carious teeth with characteristically enlarged pulp chambers in molars. Histological examination of an extracted tooth revealed an unusually wide zone of predentine with some other dentinal irregularities. No cement layer was found. The skeletal age and exfoliation of primary teeth, however, were normal, unlike most reported cases of hypophosphatasia. The patient's renal disease was treated mainly with corticosteroids. There is no treatment for hypophosphatasia.

Child↗
PubMedDate not supplied

A study of primary dental enamel from preterm and full-term children using light and scanning electron microscopy.

PURPOSE: The aim of this study was to examine the enamel thickness of the maxillary primary incisors of preterm children with very low birth weight (< 1,500 g) compared to full-term children with normal birth weight. METHODS: A total of 90 exfoliated maxillary primary central incisors were investigated using light microscopy and scanning electron microscopy (SEM). Three serial buccolingual ground sections of each tooth were examined under light microscopy, and maximum dimensions of the prenatally and postnatally formed enamel were measured. RESULTS: The enamel of preterm teeth was approximately 20% thinner than that for full-term teeth. Most of the reduction was observed in the prenatally formed enamel. This was 5 to 13 times thinner than that for full-term children (P<.001). The "catch-up" thickness of postnatally formed enamel did not compensate fully for the decrease in prenatal enamel (P<.001). Although none of the teeth used in this study had enamel defects visible to the naked eye, 52% of preterm teeth showed enamel hypoplasia under SEM, compared with only 16% found on full-term teeth (P<.001). These defects were present as pits or irregular, shallow areas of missing enamel. CONCLUSIONS: Preterm primary dental enamel is abnormal in surface quality, and is significantly thinner compared to full-term enamel. The thinner enamel is due mainly to reduced prenatal growth and results in smaller dimensions of the primary dentition.

Child, Preschool↗
PubMedDate not supplied

Primary tooth enamel surface topography with in vitro argon laser irradiation alone and combined fluoride and argon laser treatment: scanning electon microscopic study.

PURPOSE: The purpose of this descriptive scanning electron microscopic study was to characterize surface alterations in primary tooth enamel after in vitro argon laser irradiation alone and combined with topical fluoride treatment either before or after argon laser irradiation. METHODS: Twenty extracted or exfoliated primary teeth underwent soft tissue debridement and a fluoride-free prophylaxis. Buccal and lingual surfaces were determined to be caries-free by macroscopic examination (stereo-zoom binocular microscope, x16). Treatment groups were: (1) no-treatment control; (2) argon laser irradiation (ALI; 11.5 J/cm2); (3) 1.23% acidulated phosphate fluoride (APF before ALI); and (4) ALI before APF. Both buccal and lingual surfaces were evaluated following standard scanning electron microscopic preparation techniques. RESULTS: With controls, enamel surfaces were relatively smooth with occasional enamel prism ends present on their surfaces. There were no areas with cavitations or surface defects. With ALI, the lased surfaces were roughened mildly to moderately irregular without cavitation of the enamel or exposure of enamel prism ends. The surfaces possessed adherent granules to globules, with most being <3 microm in greatest dimension. Only occasional fine cracks and porosities in the surface coatings were noted and these were typically less than 1 microm in width or diameter. With APF before ALI, the surfaces possessed an irregular contour, with numerous granules to globules varying in size from 1 to 3 microm in greatest dimension. With ALI before APF, a homogenous confluent surface was present that masked typical enamel surface markings. The previously noted adherent granules and globules with argon laser treatment alone or APF before ALI were not seen. The argon laser effects on the enamel surfaces were masked by the uniformity of these surface coatings. CONCLUSIONS: Argon laser irradiation and combined APF and argon laser treatment of primary tooth enamel created surfaces that may provide a protective barrier against a cariogenic attack. The surface coatings associated with combined APF and argon laser treatment may contain fluoride-rich calcium and phosphate mineral phases that could act as reservoirs for fluoride, calcium, and phosphate and provide a certain degree of protection from a caries lesion challenge.

Acidulated Phosphate Fluoride↗
PubMed2001

Obturation of a retained primary mandibular second molar using mineral trioxide aggregate: a case report.

This case report demonstrates Mineral Trioxide Aggregate obturation of the root canal system of a retained primary mandibular second molar where no succedaneous permanent tooth was present. The technique seemed to provide a biocompatible seal of the root canal system in this case. It is not recommended for obturation of primary teeth that are expected to exfoliate since it is anticipated that Mineral Trioxide Aggregate would be absorbed slowly, if at all.

Adult↗
PubMedDate not supplied

Microcanals of dentin associated with maxillary primary anterior teeth.

PURPOSE: This study was performed to estimate the prevalence of giant dentin tubules or microcanals in primary maxillary anterior teeth. METHODS: One hundred sixty eight extracted or exfoliated primary maxillary anterior teeth were sectioned and examined by optical microscopy and image analysis. Differences in the proportion of teeth with microcanals among tooth types were tested by using the Pearson chi-square test. RESULTS: Microcanals, having the appearance of enlarged dentin tubules, were found in approximately 20% of primary central and lateral incisors, but were significantly less prevalent (3%) in primary cuspids. Microcanals occurred in a mesial distal axial plane and ran between the DEJ and the pulp chamber. When present they numbered between 1 and 43, with mean numbers of 20 and 16 in central and lateral incisors, respectively. The microcanals ranged in size between 5 and 70 microns, compared to normal dentin tubule diameters of approximately 1 micron. CONCLUSIONS: Microcanals are relatively common in primary maxillary incisors, but uncommon in primary cuspids. Additional work is needed to establish their prevalence in various teeth of both primary and permanent dentition.

Chi-Square Distribution↗
PubMedDate not supplied

The nano-hardness and elastic modulus of carious and sound primary canine dentin.

This study measured the nanohardness and elastic modulus- of carious and sound primary canine dentin and compared the values obtained under the lesion and in sound regions of incisal, center and cervical areas, and outer, middle and inner layers. Six extracted or exfoliated primary canines (three with dentin caries on both proximal surfaces and three sound teeth) were mesiodistally sectioned parallel to the long axis of the tooth and polished. The hardness (H), plastic hardness (PH) and Young's modulus (Y) were measured by a nano-indentation tester. Ten indentations at intervals of 10 microm on all regions, areas and layers were made using a load of 1 gf for one second. All indentations were observed using a microscope attached to the tester. All data were statistically analyzed using ANOVA and Scheffe's test at p < 0.05. For sound teeth, the H, PH and Y values of the inner layer were significantly lower than the outer and middle layers in all areas. The H, PH and Y values of the cervical area were significantly lower than the incisal area in almost all of the outer, middle and inner layers. For carious teeth, the H, PH and Y values of the inner layer were significantly lower than the outer and middle layers in the center area. For the center area, the H, PH and Y values under the lesion were significantly lower than sound teeth in the outer and middle layers. Dentin under the lesion, near the pulp and cervical areas showed significantly lower nanohardness and elasticity.

Analysis of Variance↗
PubMedDate not supplied

The etiology, prevalence, and sequelae of infraclusion of primary molars.

Dental infraclusion, teeth below the occlusal plane, is a common condition, especially in mandibular primary molars, with more than seventy references in the literature. Most claim infracluded molars do not exfoliate within normal time limits and must be extracted to prevent detrimental sequelae. The few documented studies on this topic suggest, however, that most infracluded teeth exfoliate normally; however, there is a tendency toward a delay of six months. The degree of infraclusion does not appear to correspond with exfoliation time. The frequent sequelae of severely infracluded teeth, space loss and molar tipping, may be prevented by either restoring the height of the affected tooth or by using space maintainers without extraction. The successors of infracluded molars reportedly develop normally and have few occlusal abnormalities.

Ankylosis↗
PubMed1993

Pleiotropy in Coffin-Lowry syndrome: sensorineural hearing deficit and premature tooth loss as early manifestations.

We report on 7 patients (6 M, 1 F) with Coffin-Lowry syndrome who have a sensorineural hearing deficit in addition to developmental delay and characteristic facial changes. One of the patients also had a history of premature exfoliation of primary teeth. These are previously unappreciated clinical signs that may aid in the early diagnosis of Coffin-Lowry syndrome. Early diagnosis and recognition of a hearing deficit in the patient can lead to the use of hearing aids to help the patient achieve his or her full potential. These "new" clinical manifestations expand the phenotype of Coffin-Lowry syndrome and constitute an additional indication of pleiotropy.

Child↗
PubMed1996

Direct access to equivocal approximal carious lesions.

Approximal carious lesions provide unique diagnostic and restorative challenges for clinicians interested in conserving tooth structure. Direct access reduces diagnostic doubt and facilitates optimal restorative management. The direct access afforded to newly erupted posterior teeth provides an incomparable window of opportunity to the proximal surfaces. Optimal management is limited to the interval between exfoliation and eruption, because access is lost once the erupting adjacent permanent teeth come into contact. Diagnostic and restorative strategies accomplished after creation of direct access to approximal lesions are discussed.

Adult↗
PubMed1992

Hexahedrally based crystals in human tooth enamel.

Mg-containing calcium phosphate crystals including pseudocuboidal, rhombohedral shapes and groupings of quadrangular blades cubically arranged were found in human tooth enamel by scanning electron microscopy and by electron probe microanalysis. In caries-free old enamel, these hexahedrally based crystals measuring 0.5-2.5 microns in length were observed in some crevices of tufts and lamellae. The crystals were rarely seen in the inner crevices of caries-free exfoliated deciduous enamel and none could be seen in sound young enamel. In brown-coloured old enamel possessing arrested caries with lamellae, some of the lamellae contained crystals measuring 0.1-1.5 mu in length adjacent to half-dissolved prisms. These crystals, identified as Mg-containing whitlockite, will grow during a long period after eruption of the tooth or during the enamel caries process.

Aged↗
PubMed2003

Immunohistochemical study of genesis of the mouse oral vestibule.

Immunohistochemical light microscopy by the enhanced polymer one-step staining (EPOS) method and immunohistochemical confocal laser scanning microscopy by the labelled streptavidin biotin (LsAB) method were performed on the developing vestibular lamina (VL) of fetal mice at stages from E11 to E14, and the immunohistochemical findings were compared with the findings in the developing dental lamina (DL) and tooth germ. pRb and PCNA were immunolocalized and found to be related to the temporal and spatial expression of cytokines and receptors in the primary epithelial band, VL, DL/enamel organ, and associated mesenchyme. The following results were obtained: 1) EGF, TGFalpha, EGFR, PCNA, FGF2, pRb, and FGFR1-4 were immunolocalized in the developing tissues. 2) Cytokine expression patterns indicated that the EGF family and FGF2 essentially induced VL generation and cell proliferation. 3) FGFR1 was diffusely localized in the primary epithelial band, but was strongly expressed in the E12-14 VL and DL/enamel organ. By contrast, EGFR internalization was observed in the differentiating E13 VL. 4) Expression of pRb was intensely localized in the stratum germinativum of the E13 VL and corresponded to CK-10 expression in the keratinizing VL. The results of this study suggest a mechanism in which FGFR1 regulates pRb to induce proliferation of cells in the VL and DL/enamel organ, and, in particular, to incite keratocyte differentiation and subsequent exfoliation of keratinizing VL cells.

Animals↗
PubMed2006

Human teeth as historical biomonitors of environmental and dietary lead: some lessons from isotopic studies of 19th and 20th century archival material.

The lead isotopic composition of various sections (crown, crown base, root) of teeth was determined in specimens collected from 19th century skulls preserved in museum collections and, upon extraction or exfoliation, from humans of known ages residing in Scotland in the 1990s. For most 20th century samples, calculation of accurate crown-complete or root-complete dates of tooth formation ranging from the 1920s to the 1990s enabled comparison of (206)Pb/(207)Pb ratios for teeth sections (crown base root) with corresponding decadally averaged data for archival herbarium Sphagnum moss samples. This showed that the teeth sections had been significantly influenced by incorporation of non-contemporaneous (more recent) lead subsequent to the time of tooth formation, most probably via continuous uptake by dentine. This finding confirmed that separation of enamel from dentine is necessary for the potential of teeth sections as historical biomonitors of environmental (and dietary) lead exposure at the time of tooth formation to be realised. Nevertheless, the mean 19th century value of 1.172+/-0.007 for the (206)Pb/(207)Pb ratio in teeth was very similar to the corresponding mean value of 1.173+/-0.004 for 19th century archival moss, although relative contributions from environmental sources - whether direct, by inhalation/ingestion of dust contaminated by local lead smelting ((206)Pb/(207)Pb~1.17) and coal combustion ((206)Pb/(207)Pb~1.18) emissions, or indirect, through ingestion of similarly contaminated food - and drinking/cooking water contaminated by lead pipes of local origin, cannot readily be determined. In the 20th century, however, the much lower values of the (206)Pb/(207)Pb ratio (range 1.100-1.166, mean 1.126+/-0.013, median 1.124) for the teeth collected from various age groups in the 1990s reflect the significant influence of imported Australian lead of lower (206)Pb/(207)Pb ratio (~1.04) and released to the environment most notably through car-exhaust emissions arising from the use of alkyl lead additives ((206)Pb/(207)Pb~1.06-1.09) in petrol in the U.K. from ca. 1930 until the end of the 20th century.

Adult↗