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Immunohistochemical localization of periostin in tooth and its surrounding tissues in mouse mandibles during development.

Previous reports have shown expression of immunoreactivity for periostin, originally identified as osteoblast-specific factor-2, in the periosteum and periodontal ligament. However, the developmental changes in its expression and the detailed immunolocalization have remained veiled. The present study was undertaken to examine the spatiotemporal expression of this protein in teeth and their associated tissues of mice during development at light and electron microscopic levels. In tooth germs at cap stage, periostin immunoreactivity was recognizable in the interface between inner enamel epithelium and preodontoblasts as well as in the mesenchymal tissues around cervical loop. Dental follicles around tooth germs at bell stage localized periostin immunopositivity in addition to the immunopositive areas observed in cap-staged tooth germs, although the functional significance of periostin has remained unclear in tooth development. Furthermore, periostin immunoreactivity was also found in the alveolar bone surface. In the incisors of both 7- and 21-day-old mice, immunoreaction for periostin was discernible in the lingual periodontal ligament and labial fibrous tissue adjacent to the papillary layer. After postnatal day 7, immunoreaction for periostin came to be restricted to the fibrous bundles in the periodontal ligament in accordance with the organization of the periodontal fibers, indicating its localization matched the morphogenesis of the periodontal ligament. Immunoelectron microscopic observation of the mature periodontal ligament verified the localization of periostin between the cytoplasmic processes of periodontal fibroblasts and cementoblasts and the adjacent collagen fibrils. Our findings suggest that periostin is involved at the sites of the cell-to-matrix interaction, serving as adhesive equipment for bearing mechanical forces, including occlusal force and tooth eruption.

Animals↗

Epidemiology of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" in patients with cleft lip and palate.

OBJECTIVE: Type and prevalence rates of the symptoms of Hoffmeister's "genetically determined predisposition to disturbed development of the dentition" were studied in patients with clefts. PATIENTS: Data of 263 patients with nonsyndromic clefts of lip (alveolus and palate) or isolated cleft palates were examined in a retrospective study. SETTING: The clefts were classified as cleft lip or cleft lip and alveolus, cleft palate, unilateral cleft lip and palate, and bilateral cleft lip and palate. All patients were scrutinized for 28 individual symptoms. Prevalences of the individual symptoms were statistically evaluated regarding cleft type and gender by using the chi-square test and were also compared with findings in patients without clefts. RESULTS: In 97.7% of the patients with clefts, at least one symptom was found. Microdontia of individual teeth, hypodontia, and hyperodontia were the symptoms most frequently recorded. Comparison of the different cleft types revealed differences regarding the prevalences of supernumerary lateral incisors (p = .051), infraposition of deciduous molars (p < .001), and atypical tooth bud position (p = .030). Comparison of the prevalences of 10 symptoms recorded in the patients with clefts with the prevalences recorded in patients without clefts showed nine symptoms were found much more frequently in the population with clefts. CONCLUSION: These findings support the hypothesis that clefting is part of a complex malformation associated with other dental anomalies resulting from disturbed development of the dentition. Patients with clefts are also likely to present other deficiencies of dental development and tooth eruption in both dentitions, even in regions not affected by the cleft.

Adolescent↗

[A case of injured unerupted permanent tooth in a child].

Children with trauma visit frequently the department of oral and maxillofacial surgery. The treatment for injured permanent teeth is different from that for injured deciduous teeth. We have experienced a case of a 9-year-old boy with an injured unerupted immature permanent tooth with tooth crown fracture. When the tooth erupted gradually, fractured pieces were removed three times, and indirect pulp capping was performed. Three years after the injury eruption was almost completed and pulp was alive, even though the dental roentgenograph showed obliteration of the crown pulp cavity.

Child↗

Studies on the development of the articular part of the temporal bone with special reference to the postglenoid process.

The development and significance of the postglenoid process on the articular surface of the temporal bone were studied using 217 Indian skulls, which were divided by their level of tooth eruption into 6 developmental stages; preeruption period (Stage I), initial stage (m1 eruption) of the deciduous dentition period (Stage II), middle stage (m2 eruption) of the deciduous dentition period (Stage III), late state (eruption of 20 deciduous teeth) of the deciduous dentition period (Stage IV), mixed dentition period (Stage V), and permanent dentition period (Stage VI). Each skull was mounted on a Kraniophor in such a way that the auriculoorbital (Frankfurt) plane was positioned vertical to the horizontal plane and photographed at a focal distance of 40 cm. Using the Frankfurt plane as a base line, the vertical distances to the lowest point of the postglenoid process (a-A), to the deepest point of the mandibular fossa (b-B), and to the mid-point of the articular tubercle (c-C) were measured. The distances from various points of the mandibular fossa to the articular surface of the temporal bone were measured at the level of the Frankfurt plane. The results may be summarized as follows: The length of the postglenoid process as measured from the Frankfurt plane was 0.58 mm at Stage I and 0.75 mm at Stage II. It increased by 0.6-1.0 mm at each developmental stage. By Stage VI, it had increased to 3.85 mm (six- to seven-fold increase from the initial value). The anteroposterior width of the postglenoid process remained almost unchanged throughout the developmental stages. The growth of the articular structures of the temporal bone from the preeruption to deciduous dentition period increased 73% in the total anteroposterior dimension (5.22 mm) and 44% in the total vertical dimension (3.32 mm). The vertical dimension of the mandibular fossa began to rapidly increase following the eruption of the deciduous first molars.

Adolescent↗

Regional odontodysplasia.

An unusual case of regional odontodysplasia in an 8-year-old boy is presented. He was referred to our clinic because of failure of tooth eruption on the left side of the maxilla and frequent fever attacks. Treatment consisted of extraction of the affected teeth, and removal of inflamed tissue.

Child↗

Mineral content of calcified tissues in cystic fibrosis mice.

Although abnormal hard tissue mineralization is a recognized complication of cystic fibrosis (CF), the pathogenesis leading from the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein is poorly understood. We hypothesized that CFTR plays a direct role in the mineralization of bone and teeth and tested the hypothesis using CF mouse models [CFTR(-) mice]. In vivo measurements by dual-emission X-ray absorpitometry (DEXA) indicated that bone mineral density (BMD) was reduced in CF mice as compared to gender-matched littermates. However, no change was evident after correction of BMD for the covariant of body weight. The latter finding was confirmed in isolated femurs and nasal bones by standard dry-ashing and instrumental neutron activation analysis (INAA). INAA of the continuously growing hypsodont incisor teeth from CFTR(-) mice revealed reduced Ca and normal P in the enamel layer--a finding consistent with changes in the deciduous teeth of CF children. Interestingly, enamel fluoride was increased in the CFTR(-) incisors and may associate with abnormal enamel crystallite formation. The iron content of the incisor enamel was reduced, explaining the loss of yellow pigmentation in CFTR(-) incisors. In contrast to the incisors, the mineral content of the slow-growing brachydont molar teeth was not different between CFTR(-) and CFTR(+) mice. It was concluded that CFTR does not play a direct role in the mineralization of bones or brachydont teeth in mice. Functional CFTR is apparently required for normal mineralization of the hypsodont incisors. However, multiple changes in the mineral composition of the CF incisors suggest an indirect role for CFTR, perhaps by maintaining a normal salivary environment for continuous tooth eruption.

Animals↗

Postnatal development of periodontal ruffini endings in rat incisors: an immunoelectron microscopic study using protein gene product 9.5 (PGP 9.5) antibody.

Postnatal development of Ruffini endings was ultrastructurally investigated in the upper incisors of the rat from 1 day to 60 days after birth by means of protein gene product 9.5 (PGP 9.5) immunocytochemistry. The immunostaining with PGP 9.5 antibody clearly demonstrated chronological alterations of the distribution and ultrastructure of the Ruffini endings during postnatal development. At 1 day after birth, the PGP 9.5-positive nerve terminals contained a few mitochondria and vesicles immunonegative for PGP 9.5. Dendritic terminals appeared at 4 days after birth, with a small number of expanded or bulbous portions. These expanded portions possessed morphological features similar to those of the growth cone: several mitochondria and various kinds of vesicles. Typical Ruffini endings with dendritic ramification and expanded portions appeared 7-11 days after birth. At this stage, parts of the axon terminals extended through the slits of Schwann cell covering and formed finger-like projections called axonal spines. These Ruffini endings increased dramatically in number after 24-26 days and were identical in density and morphology to those seen in adult rats. After the commencement of the occlusion between the incisors, the number of large mitochondria increased, in contrast to the decrease of the vesicles in the axon terminals. Moreover, the axonal spines increased both in number and in length. Thus, the periodontal nerve endings showed stage-specific morphological features intimately related in timing to tooth eruption and occlusion. Functional stimuli possibly contribute to the final differentiation and maturation of the periodontal Ruffini endings.

Age Factors↗

Hereditary gingival fibromatosis with distinct dental, skeletal and developmental abnormalities.

A case of a 9-year-old child with hereditary gingival fibromatosis, supernumerary tooth, chest deformities, auricular cartilage deformation, joint laxity and undescended testes is described. The exact mode of inheritance is unclear; a new mutation pattern is possible. These features resemble but differ from the previously reported Laband syndrome. The dental treatment consisted of surgical removal of the fibrous tissue and conservative restorative treatment under general anesthesia. The dental practitioner should be alert for developmental abnormalities such as supernumerary teeth and delayed tooth eruption. A comprehensive medical history and physical systemic evaluation is essential to rule out other systemic abnormalities. Genetic consultation is mandatory for future family planing.

Abnormalities, Multiple↗

Dental and skeletal relationships to attritional occlusion.

Dental attrition has been investigated in depth. Besides alterations in arch length due to attrition, skeletal and intra-arch differences were discovered. It is felt that these findings do have value in helping us realize that present-day concepts of proper occlusion cannot necessarily be applied to dentitions that existed at another time. A more thorough knowledge of occlusions exhibiting dental attrition provides information that is helpful in understanding more fully the nature of tooth eruption and associated dental arch occlusion and the interrelationships of these factors with supporting skeletal structures.

Cephalometry↗

Effect of epidermal growth factor on expression of transforming growth factor-beta 1 mRNA in stellate reticulum cells of rat mandibular molars.

Cultured stellate reticulum cells isolated from rat mandibular molars respond to incubation in EGF by increasing their level of expression of TGF-beta 1 mRNA. Northern blots showed that incubation in EGF for 6 hours stimulated over a two-fold increase in TGF-beta 1 mRNA in the cells. In contrast, incubating the cells in TGF-beta 1 did not enhance the expression of TGF-beta 1 mRNA in the cells, indicating that TGF-beta 1 does not have an autocrine effect on these cells. Immunocytochemistry showed that EGF receptor was present on the surface of many but not all of the cultured stellate reticulum cells. Because EGF does stimulate premature eruption of teeth, it is possible that its effect on the stellate reticulum region of the enamel organ would be to stimulate synthesis of TGF-beta 1 mRNA which, in turn, could lead to increased synthesis of TGF-beta 1 by these cells. The cells do contain the TGF-beta 1 protein as revealed by immunocytostaining. The newly synthesized TGF-beta 1 may exert its effect on the adjacent dental follicle to either initiate the onset of the cellular events of tooth eruption or to increase the secretion of extracellular matrix proteins by the follicle for formation of the periodontal ligament.

Animals↗

Effects of anti-EGF serum on newborn mice.

Administration of anti-EGF serum to newborn mice led to delay of eyelid opening and incisor tooth eruption, acceleration of hair growth and delay of weight gain. These results indicate that in the first week after birth EGF still has a physiological function, which can be abrogated by anti-EGF serum.

Animals↗

Association between mother-infant salivary contacts and caries resistance in children: a cohort study.

We selected 327 7-month-old infants and divided them into two groups based on the frequency of salivary close contacts between mother and infant. Five to seven years later, all first-born children (N = 55) whose dental development had been followed regularly, were examined for dental caries and prevalence of salivary mutans streptococci (MS) and lactobacilli. The children with frequent maternal close contacts (F group, N = 21) had significantly less MS in saliva than the children with rare close contacts (R group, N = 34, P = 0.02). Only 19% of the children in F group compared with 56% in R group had experienced caries in their primary molars and/or canines (P < 0.01). A significantly greater proportion of the children in F group (57%) than in R group (27%, P < 0.05) had a high intake of sugar-containing foods and drinks in a 2-day dietary history. The F and R groups did not differ significantly with respect to other children's caries risk factors, or in age, sex, stage of dental development, dental treatment, or the social aspects studied. There were no significant differences between F and R groups in maternal caries experience, salivary MS or lactobacillus counts, or in maternal background factors (age, breast feeding, or education). Frequent transfer of maternal saliva to the mouth of the baby before tooth eruption was negatively associated with oral infection by MS and to caries in the primary dentition, possibly due to protective immune mechanisms.

Adult↗

Unusual manifestations in X-linked amelogenesis imperfecta.

This paper describes a female with X-linked amelogenesis imperfecta (XAI). This case is unusual in having taurodontism, pulpal calcifications, coronal defects prior to tooth eruption and unerupted teeth. These findings have been reported in some cases of autosomal dominant and autosomal recessive AI but have not previously been documented in XAI.

Adolescent↗

Localization of epidermal growth factor receptors in cells of the enamel organ of the rat incisor.

Epidermal growth factor (EGF) is a peptide shown to effect precocious incisor tooth eruption in rat pups. Binding sites for EGF were visualized in the continuously erupting adult rat incisor by light and electron microscope radioautography after in vivo injection of 125I-EGF. These binding sites represented EGF receptors because of (i) competition between 125I-EGF binding at 2 min after injection and a coinjected excess of unlabeled EGF; (ii) the receptor-mediated endocytosis of 125I-EGF at 15 and 30 min after injection; and (iii) the demonstration of EGF receptor kinase activation in vivo. The stem and the mitotic cells in the epithelial odontogenic organ at the growing end of the tooth develop into two nondividing layers of the enamel organ: (i) ameloblasts which secrete enamel and are subsequently involved in the enamel maturation process, and (ii) papillary layer cells situated between the blood supply and the ameloblasts. Although few EGF receptors were present at the mitotic end, receptor density was highest at the mature end of the enamel organ. High levels of 125I-EGF binding were found on papillary layer cells and ruffle-ended, but not smooth-ended, ameloblasts. This implies a cyclical exteriorization and internalization of receptors during modulations between the two cell types. These data suggest that the EGF receptor mediates a major function of the enamel organ in the formation of enamel.

Animals↗

Endodontic therapy as an adjunct for treatment of juvenile periodontitis: case report.

The four first permanent molars in a 16-year-old girl with juvenile periodontitis were treated by selective grinding, tooth eruption, conventional periodontic treatment and endodontic therapy. The endodontic treatment was carried out as an elective procedure under ideal conditions, thereby pre-emptying the emergency treatment which would have been necessary following occlusal reduction. The two-year follow-up examination showed successful resolution of the original condition.

Adolescent↗

Idiopathic external resorption of teeth.

An unerupted maxillary third molar tooth from a 57-year-old Caucasian male, which showed radiographic evidence of crown resorption, but was otherwise symptomless, was examined post-extraction by light and scanning electron microscopy. (SEM) Appearances of the residual dental tissues were consistent with a diagnosis of an invading external resorption with formation of pulpal granulation tissue, dentinal resorption and some dentinal metaplasia. SEM of crown fragments indicated a generally uniform pattern of enamel resorption, for which the ameloblasts rather than multinucleate cells were implicated. By extrapolation of the activity of the former cells during the late stages of amelogenesis and tooth eruption, it is suggested that resorptive activity of and by enamel epithelium may explain not only the coronal origin of this type of idiopathic resorption, (which is otherwise unexplained), but also its progress into the pulp and the pulp reactions.

Dental Enamel↗

Experimental odontomas in osteopetrotic op/op rats.

Osteopetrosis is an autosomal recessive disease in several mammalian species. Osteopetrotic op/op rats suffer from complete failure of tooth eruption related to reduced bone resorption. In our earlier studies, op/op rats grafted with bone marrow cells 3 days after birth were cured of the disease and their molar eruption was restored. However, the incisors failed to erupt and their proliferating ends were distorted, forming odontomas. The purpose of the present investigation was to study the odontogenic tissues in the odontomas, using the correlated techniques of radiography and microradiography of undecalcified material, together with histology of decalcified material and scanning electron microscopy.

Animals↗