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PubMed1996

In vitro characterization of enamel epithelium and pulp cells in mouse tooth germs.

Mixed cell populations consisting of enamel epithelium and pulp cells obtained from 18-day embryonic mouse tooth germs were cultured in vitro. Epithelial cells and pulp cells were also cultured individually and examined. Isolated cells were cultured in alpha-MEM supplemented with 10% fetal bovine serum for up to four weeks and examined morphologically using histological procedures including immunostaining, light and electron microscopy, and electron probe microanalysis. The pulp cells proliferated and differentiated in the absence of epithelium, but the number of epithelial cells showed a strong dependence on the pulp cells. Pulp cells showing fibroblastic morphology in the mixed culture gradually became elliptical, and eventually transformed into spherical cells surrounded by a calcified extracellular matrix. Alkaline phosphatase (ALPase) activity was expressed on the pulp cells prior to calcification of the extracellular matrix, as shown by von Kossa's and alizarin-red staining. Calcification deposition, which is closely associated with thick banded type-I collagen fibrils, was shown to be composed of calcium and phosphorous using electron probe microanalysis. Type-I collagen immunoreactivity was detected on the extracellular matrix after two weeks of culturing. The present results show that the proliferation and differentiation of pulp cells, and subsequent calcification of the extracellular matrix occur in the presence or absence of epithelial elements, but that the proliferation of epithelial cells depends on the presence of pulp cells.

Ameloblasts↗
PubMed1995

Clinical and historical predictors of dental caries on radiographs.

This report evaluates the efficacy of the clinical predictors of caries proposed in the USA FDA guidelines for prescribing dental radiographs. The clinical findings that best associate with the presence of any caries where a history of pain, a defective restoration, unusual calcification, and an abutment tooth for a fixed or removable prosthesis. There is a group of measures of periodontal disease that were also weakly associated with the presence of caries. The best predictors of caries extending into the dentin were the presence of clinically defective restorations, a history of pain, and signs of periodontal disease. Proximal lesions are likely to appear on teeth with defective restorations, unusual calcification or large or deep restorations. The best predictors of radiographic root caries are periodontal findings such as furcation involvement, increased mobility, a history of periodontal therapy and gingival recession. While the specificities for these findings were generally high, the sensitivities and positive predictive values were usually under 50%, and often much lower. Thus these clinical findings cannot successfully be used as exclusive criteria for ordering radiographs for caries detection. Because caries is found fairly frequently, and because we are unable to identify tooth-specific criteria with clinically useful sensitivity and specificity values, these data support the FDA panel recommendation of bitewing examinations for all new patients and at periodic intervals for recall patients.

Confidence Intervals↗
PubMed1989

[Observation on calcification of necrotic tissue in pressure side of periodontal membrane incident to experimental tooth movement].

In an orthodontic point of view, it is said that necrotic tissues cause a standstill of tooth movement until they disappear and that term of the standstill is related to the size of the necrotic tissues. Although remodeling processes of a periodontal membrane in compressed area were reported as series of phenomena like degeneration, coagulative necrosis, calcification and histiolysis, there is no direct evidence that the necrotic tissue is really calcified. The purpose of this study is to clarify histologically whether the necrotic tissues in the periodontal membrane are calcified or not and to know when appearance and disappearance of the calcification occur during an experimental tooth movement. Twenty eight rats were used for this study. For the experimental tooth movement, the orthodontic elastics were inserted into the interproximal space between the maxillary right 1st and 2nd molars during 1, 2, 3, 5, 7 and 14 days respectively (Waldo's method). The periodontal tissues were observed on undecalcified sections by vital staining in which oxytetracycline (3 mg/kg), alizarin red (8 mg/kg) and calcein (0.8 mg/kg) were applied as well as by contact micro radiography (CMR). Findings were as follows: 1) After 2 days of tooth movement, a part of the periodontal membrane in compressed area showed fluorescence by vital staining and was radiopaque by CMR. This means that the necrotic tissues are really calcified at least after 2 days of experimental tooth movement. 2) After 7-14 days no calcified tissue could be found in the periodontal membrane. The calcified tissues may disappear under processes of resorption in this area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Repair of untreated root fracture: a case report.

A case is presented in which an untreated root fracture in a maxillary central incisor of an adult male was found radiographically 10 years after injury. The tooth was removed and the area of the root corresponding to the fracture line was examined by SEM while the remaining tooth was processed for decalcified sections. Calcification of the coronal pulp associated with extensive tissue atrophy and normal pulp tissue apically was observed. Two barriers composed of dentinal and cemental hard tissue were present apically in the coronal fragment and in the fracture line.

Adult↗
PubMed2003

[Effects of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) on the formation of dental hard tissue of mouse molar tooth germs in organ culture system].

In the developing tooth, 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) causes hypoplasia and hypomineralization of enamel and dentine. The present study was undertaken to clarify the effects of HEBP on the formation of dental tissues of tooth germs in an organ culture system. Mandibular first molars from 17.5-day-old mouse embryos were cultured with or without 250 microM HEBP in culture medium. Cultured tooth germs were analyzed by histological examination and by immunohistochemical localization using anti-amelogenin antibody. In cultured tooth germs treated with HEBP before the commencement of calcification in dentine, calcification of dentine matrix was inhibited completely and enamel formation was not observed. Ameloblasts were directly adjacent to dentine matrix. However, immunohistochemical data indicated that these ameloblasts secreted amelogenin. In the experiments of adding HEBP to cultured tooth germs on culture day 13, calcified dentine and enamel had formed before the administration of HEBP, but the dentine matrix newly formed after the administration of HEBP had not calcified. It was confirmed by immunohistochemical observations that enamel matrix-like material had penetrated into uncalcified dentine matrix and accumulated in dental papilla of tooth germs. However, no enamel matrix-like material was observed in calcified dentine and predentine underneath the calcified dentine by immunohistochemical staining. From these results, it might be concluded that ameloblasts secreted enamel matrix in the presence of HEBP and diffused through uncalcified dentine matrix into dental papilla. These findings suggests the calcification of dentine might be essential for the physical barrier to accumulate the enamel matrix and form a distinct layer of enamel as enamel.

Amelogenin↗
PubMed2005

The fate of a mid-root fracture: a case report.

The present report describes a case of a mid-root fracture in a maxillary central incisor of a 19-year-old patient. The fractured tooth was splinted with composite that was removed only 3 years later, as the patient did not appear for follow-up examinations. At this time, the radiographs revealed a normal periodontal ligament, rounding of the borders of the fragments and pulp obliteration of both fragments. Eight years later, the tooth was clinically normal and blurred calcification of the root canal was disclosed radiographically. After 13.5 years the patient complained of tooth mobility and radiographic examination revealed an advanced cervical root resorption. As no conservative approach was possible at this stage, the patient was referred to a prosthodontist for esthetic rehabilitation.

Adult↗
PubMed1991

[Sequence in calcification and eruption of second premolars and molars--a longitudinal study].

Investigation was done with the purpose of establishing frequency of eruption and calcification of P2 and M2 and to perform a longitudinal analysis of certain types, observing the changes during growth, character of these changes and their durability. Analysis was done on 354 orthopantomographic radiographs of orthodontic patients from Nis, aged 7 to 12 years. Eruption phase was determined on the bases of vertical relation to M1 Development phase was determined with the help of a table with 11 developmental phases. Depending on tooth in predominance, patients were divided into three groups: P2M2, (P2M2) and M2P2. All three types of eruption and calcification were recorded. (P2M2) eruption is dominant in maxilla, while M2 has some advantage in mandible. In calcification of both jaws, type P2M2 is predominant in both sexes. In later age, eruption shows changes of type-in 31% to 39% of cases, but this percentage is lower in calcification-from 22% to 25%. Relation of P2 and M2 in eruption is not permanent and changes with growth: in maxilla, P2 has synchronous position in relation to M2 until 8 years of age, to gain advantage in later years; in mandible, P2 has lower position until 10 years of age, to start quicker growth in eleventh year so that in 42% of cases it erupts before M2. In development phase, P2 has advantage in both jaws. P2M2 type shows least changes with age. Other two types change into type P2M2 in 40% of cases. Once set sequence of eruption and calcification cannot be a reliable indicator of later growth since considerable changes were observed in most patients.

Bicuspid↗
PubMed1990

Pulp calcifications in primary teeth.

Information regarding the prevalence of pulp calcifications in primary teeth is lacking. The occurrence of pulp calcifications in 120 primary maxillary and mandibular extracted teeth was evaluated radiographically. Twenty-five percent of second molars presented evidence of pulp calcifications; approximately 3% of central incisors were calcified. No other categories of teeth displayed pulp involvement. The low occurrence of pulp calcifications in primary teeth support the view that the occurrence of pulp calcification increases with age.

Age Factors↗
PubMed1995

Unpredictable teeth.

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Dental Pulp Calcification↗
PubMed1990

Pulp calcifications in primary teeth.

One hundred and twenty primary maxillary and mandibular extracted teeth were collected to study the occurrence and nature of pulp calcifications. The teeth were serially sectioned, stained with hematoxylin and eosin, examined by light microscope. Pulp calcifications were observed in 31 (25.8%) teeth. Two types of pulp calcifications were noticed i.e., diffuse calcifications and free/attached type denticles. The occurrence of pulp calcification appears identical in all teeth except in the first primary molar which is statistically not significant (P greater than 0.05). The low prevalence of pulp calcifications in the primary teeth support the view that pulp calcification increases as the age advances.

Dental Pulp Calcification↗
PubMed1993

Electron probe micro-analysis of human dental pulp stones.

The mineral composition of ten human dental pulp stones presenting various morphological aspects has been studied by electron probe micro-analysis. The denticles were composed of two major chemical elements: Ca and P with mean concentrations 32.12% and 14.69% respectively giving a Ca/P weight ratio of 2.19 which is very close to the weight ratio of pure stoichiometric hydroxyapatite (2.15). The concentration of some other elements was much lower (0.88% for F; 0.75% for Na; 0.51% for Mg). The other analysed constituents (K, Cl, Mn, Zn, Fe) were present at trace concentrations. The mineral composition of sound human dentine from one tooth containing a pulpal calcification was also analysed for comparative purpose.

Calcium↗