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Results for “DENTIN, SECONDARY”

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At least 19 recordsLinked to original sources
PubMed1985

Scanning electron microscopic observations of casts of human dentinal tubules along the interface between primary and secondary dentine.

A scanning electron microscope cast technique was used to examine the interface between primary and secondary dentine in young and old human teeth. In addition, more traditional methods were used to examine this interface with light microscopy, identical regions being viewed before and after demineralization. No continuity was seen between the tubules in primary dentine and those in irregular secondary dentine in the scanning electron microscope preparations. These preparations did show the tubules to be continuous between primary dentine and regular secondary dentine in young and old teeth. Both the scanning electron microscopic and light microscopic observations suggested that regular secondary dentine becomes highly sclerosed in old teeth.

Adult↗
PubMed1977

Microscopy of the junctional region between human coronal primary and secondary dentine.

The juction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid-etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid-soluble then the peritubular matrix of primary dentine.

Cuspid↗
PubMed1992

Amount of secondary dentin as an indicator of age.

The amount of secondary dentin in a tooth has been used as one of several parameters in methods for age estimation. Dentin deposition has been measured according to various scoring systems, and the Pearson correlation coefficient with age has been found to be approximately 0.6. In the present study of 1000 teeth, molars excluded, secondary dentin was estimated according to three scoring systems. The teeth were prepared according to the half tooth technique. In addition, the area of the coronal pulp and the widths of the root and pulp chamber were measured in a stereomicroscope at the cemento-enamel junction and at three other defined points along the root. The Pearson correlation coefficient between age and secondary dentin varied in different types of teeth. Of the scoring systems, scores according to Johanson were most strongly correlated with age (r = 0.59 to 0.74). Correlation between age and the coronal pulp area varied from -0.47 to -0.72, and the range between age and ratio between pulp- and tooth width at the cemento-enamel junction was from -0.46 to -0.77. Correlations between age and ratio between sum of pulp widths and the sum of tooth widths for all four such measurements ranged from -0.58 to -0.81. Multiple regression analyses showed that by combining several types of measurements, the correlation with age was increased. A tendency was also observed towards reduced speed of secondary dentin formation in the elderly and in women.

Age Determination by Teeth↗
PubMed1982

Rate of formation of regular and irregular secondary dentin in monkey teeth.

An in vivo hard-tissue labeling technique was used to study the formation of regular and irregular secondary dentin in thirty-one monkey teeth. The formation of regular secondary dentin averaged 0.8 micrometer per day. No difference was found in the rate of formation of regular secondary dentin and irregular secondary dentin associated with attrition. The formation of irregular secondary dentin following restorative procedures averaged 2.9 micrometers per day. During the first 30 postoperative days less irregular secondary dentin was formed subjacent to deep cavities as compared to shallow ones. This could be the result of an initial injury to the odontoblasts caused by the operative and/or restorative procedures.

Animals↗
PubMed1997

SEM examination of secondary dentine under and opposite cervical carious lesions.

The deposition of calcified secondary dentine underlying carious lesions and on the wall opposite to the carious lesions was examined in this study. Twenty single rooted human teeth were used in this work. The teeth were cleaned and fractured into two longitudinal halves, which were examined under a scanning microscope. The results showed complete disappearance of the dentinal tubules, globular mineralized deposits, and mineralized deposits of fibrous morphology underlying carious lesions, while on the dentinal walls opposite to the carious lesions were calsospherites, mineralized secondary dentine, and typical deposition of secondary dentine.

Adult↗
PubMed1990

Secondary dentin in replanted teeth--a histometric study.

To quantify the secondary dentin formation in replanted teeth, 16 human premolars with a postoperative observation period of 6, 12 and 24 weeks were studied histometrically. In spite of marked intra- and interindividual variations, a regression analysis revealed a significant correlation (r = 0.70) between observation time and the quantity of secondary dentin in the coronal pulp registered by histometry. A comparison with a previous semiquantitative interpretation of the same material showed that the histometric method was more accurate.

Dentin, Secondary↗
PubMed1995

Enhanced formation of secondary dentin in the absence of nerve supply to feline teeth.

This investigation was designed to study the formation of secondary dentin in permanent teeth of young cats after denervation. In eight animals, cervical dentin was exposed bilaterally in the mandibular canines, 7-10 d after unilateral resection of the inferior alveolar nerve. The observation intervals were 30 d, 90 d and 180 d, after which histological examination of dentin was performed. In order to verify the loss and regeneration of pulpal innervation and an intact blood supply, blood flow responses to electrical stimulation of the tooth and to i.v. injections of substance P (SP) were recorded by laser Doppler flowmetry before and at 7-10 d after denervation, at the end of the experiments, and at predetermined intermediate intervals. SP-induced vasodilation was significantly enhanced at 1 wk and 30 d postoperatively and was normalized to control values at 90 and 180 d. Vasodilation in response to electrical tooth stimulation, which was absent after denervation, reappeared after 90 d in two of four cats. There was no irregular dentin formation under the exposed dentin at any time in denervated or control teeth. Formation of regular secondary dentin appeared to be enhanced on the denervated side at 30 d and 90 d postoperatively, whereas at 180 d there was no difference between sides. The results indicate that intradental nerves influence secondary dentin formation in feline permanent teeth.

Animals↗
PubMed1989

Comparative study of the composition of primary and secondary dentine.

There is considerable variation in the composition of primary and secondary dentine. In general, secondary deposits, regardless of type, contain less calcium, phosphorous, and collagenous matrix per unit volume when compared to primary dentine. Fluoride levels show the reverse tendency. These observations suggest a more open, porotic structure for secondary deposits.

Calcium↗