Human Deciduous Dentition Research Articles

Five canalled and three-rooted primary second mandibular molar.

A thorough knowledge of root canal anatomy and its variation is necessary for successful completion of root canal procedures. Morphological variations such as additional root canals in human deciduous dentition are rare. A mandibular second primary molar with more than four canals is an interesting example of anatomic variations, especially when three of these canals are located in the distal root. This case shows a rare anatomic configuration and points out the importance of looking for additional canals.

Effect of prenatal and postnatal fluoride on the human deciduous dentition. A literature review.

Fluoride passes from the mother to fetal teeth. Much of the fluoride is taken up in secretory enamel, probably by the forming mineral apatite crystals. Some is retained with residual proteins. The low concentration of fluoride in the inner enamel is incorporated mainly during the secretory stage, while the enhanced concentration in the surface enamel is produced during the much longer maturation stage. Mature, hard enamel is generally absent during fetal life. The clinical question is whether prenatal fluoride imparts an additional benefit to the universally accepted effect of postnatal fluoride. In general, surface enamel fluoride levels of deciduous teeth increase with increasing pre- and postnatal fluoride administration. A consistent level of caries protection has been reported with pre- and postnatal administration of fluoride unrelated to the acquisition of fluoride in the surface enamel. Many children develop enamel opacities in their deciduous dentition related by various factors to enamel mineralization disturbances in drinking water areas even low in fluoride. Accumulation of fluoride due to an increased fluoride intake is a feature of fluorosed enamel in the deciduous as well as permanent dentition. The resulting mature fluorosed enamel retains a relatively high proportion of immature matrix proteins onto the crystal surface. The degree of fluorosis of the deciduous dentition is less compared with that of the permanent dentition, due probably to a partial protection afforded by the maternal loss of fluoride, formerly known as the "placental barrier".

Spacing in the human deciduous dentition in relation to tooth size and dental arch size

Dental casts of 243 preschool children, 129 males and 114 females, aged 2.5–5.5 years, were analysed for the presence of interdental spaces, mesiodistal crown diameters, intercanine width, intermolar width and arch length (circumference). The prevalence of primate spaces (diastemata mesial to the upper canines and distal to the lowers) varied from 65 to 90% by arch and sex; it was lowest in the lower arch especially in females, and highest in the upper. These prevalences did not increase with age; however, other spaces which usually occur between incisors may develop towards the end of the deciduous dentition, commonly in arches with primate spaces. Generally, spacing of the deciduous anterior teeth was significantly related to mesiodistal crown diameter and intercanine arch width. The crowns were significantly broader and the arches significantly narrower in cases with no spaces than in those where spaces existed. As the genetic programming for tooth size also normally affects arch size, greater discrepancies between mesiodistal crown diameters of the deciduous anterior teeth and their permanent successors are probably associated with more deciduous arch spacing.

Gingivitis in the human deciduous dentition. A correlative clinical and block surface light microscopic (BSLM) study.

This study examined the relationship between clinical and histomorphometric parameters in the human deciduous dentition. Clinical parameters including plaque index, gingival swelling, gingival color, tooth mobility and degree of root resorption were determined prior to the extraction of teeth. The teeth were extracted with their surrounding gingiva in order to preserve the in situ relationship between the hard and soft tissues. Histomorphometric analysis was carried out on 55 sites, using block surface light microscopy (BSLM). Apical migration of the junctional epithelium was found at 53% (29) of the sites. The gingival sulcus was shallow (0.3 +/- 0.19 mm) and coronal to the cemento-enamel junction at 84% (46) of the sites. Junctional epithelium with retepegs was present at 89% (49) of the sites, whilst an inflammatory cell infiltrate (ICI) was present at all sites examined. The ICI was located opposite to the junctional epithelium and cementum at 80% (44) of the sites. The extent of ICI correlated positively with the patients' age and was significantly increased when clinical evidence of gingival swelling or redness was present.

The origin of tooth number of the human deciduous dentition: a hypothesis

The constant number of 5 teeth per quadrant in the human deciduous dentition is seen to be a result of the mitotic activity within the dental lamina which leads to a constant number of centers in which cells are compressed together. These centers in which, due to the compression, the cells become narrow and cylindrical and, due to subsequent bulging, wedge-shaped, are the prerequisite for the formation of the constant number of five tooth buds per quadrant.

A histological study of the chronology of initial mineralization in the human deciduous dentition

Accurate dating of initial mineralization in the dentition was derived from fetuses aged according to the maternal history, assessment of gestational age by obstetricians, paediatricians and pathologists, histological evaluation of their cerebellar and renal development, and accurate measurements of crown-rump length, skull circumference, brain and body weight. Serial sections of the jaws of 121 fetuses ranging from 10 to 26 weeks post-menstrual age first showed mineralized dentine in the deciduous central incisor at 15–19 weeks, in the lateral incisor at 16–21 weeks, in the canine at 19–22 weeks, in the deciduous first molar at 16–19 weeks and in the second molar at 20–22 weeks. These age ranges differ from those for initial mineralization common in textbooks, particularly for the molars.

A clinical and histometric study of gingivitis associated with the human deciduous dentition.

This study examined the relationship between clinical indices and the histologic parameters associated with the gingiva of the human deciduous dentition. The plaque index, gingival swelling and color, probing depth, bleeding on probing, contact with adjacent teeth and the degree of root resorption of 58 deciduous teeth were recorded. The teeth were extracted with their surrounding gingiva and prepared for histologic examination. The area of epithelium and connective tissue with and without inflammatory cells was measured as well as the epithelial length from the gingival margin including the junctional epithelium. When these measurements were grouped according to the values of the clinical indices, nonmobile teeth were found to have less epithelium than those with mobility and gingiva with a healthy color had a significantly smaller inflammatory cell infiltrate than red gingiva. Bleeding and increased probing depth were not associated with the other clinical signs of inflammation. The amount of plaque did not correlate with the measures of clinical inflammation. The inflammatory cell infiltrate was present irrespective of whether the gingiva was clinically normal or not and the inflammation did not correlate with the amount of plaque.

A GRAVIMETRIC STUDY OF CROWN GROWTH RATE OF THE HUMAN DECIDUOUS DENTITION.

A GRAVIMETRIC STUDY OF CROWN GROWTH RATE OF THE HUMAN DECIDUOUS DENTITION.

胎生期における人の乳歯石灰化の時期と様式

胎生期における人の乳歯石灰化の時期と様式

Criteria for Classification of Crown Characters of the Human Deciduous Dentition

Criteria for Classification of Crown Characters of the Human Deciduous Dentition

Calcification of the human deciduous teeth

Results of an examination of 95 human fetuses indicate that textbooks in the fields of dental anatomy, histology and embryology have erred in assertions relating to three concepts pertaining to the calcification of the human deciduous dentition. It has been found that: (1) initial calcification begins in the deciduous central incisors as early as 12 weeks or as late as 16 weeks; (2) the sequence of initial calcification is rigid, and does not run in regular sequence from the central incisor to the second molar, and (3) there is no evidence for more than one center of calcification either for the deciduous incisors or cuspids. Results of an examination of 95 human fetuses indicate that textbooks in the fields of dental anatomy, histology and embryology have erred in assertions relating to three concepts pertaining to the calcification of the human deciduous dentition. It has been found that: (1) initial calcification begins in the deciduous central incisors as early as 12 weeks or as late as 16 weeks; (2) the sequence of initial calcification is rigid, and does not run in regular sequence from the central incisor to the second molar, and (3) there is no evidence for more than one center of calcification either for the deciduous incisors or cuspids.