Morphological variations between English population samples.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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As part of a longitudinal study of dental development in a group of low birthweight children (LBW), study models of 72 children at age 7 years were measured to determine the tooth-crown size of primary molars and canines and to compare the findings with equivalent measurements in 60 normal birthweight (NBW) controls. Mesiodistal (length) and buccolingual (width) dimensions were measured manually, using dial calipers. Primary canines and molars were smaller in the LBW than the controls, with significance values ranging from P < 0.001 for the mesiodistal dimension of maxillary and mandibular canine (> 4% difference) to a non-significant difference P < 0.2 for the buccolingual dimension mandibular first primary molar (1.8% difference). Within the LBW group there was a positive correlation between birthweight and mesiodistal tooth size. Small primary tooth size in LBW children may be influenced by both genetic and environmental factors. The shorter prenatal growth period and poor perinatal and early postnatal development may influence the developing deciduous dentition. Small primary tooth-crown size, associated with LBW, should be considered in all population studies of tooth size.
Altogether 2159 pregnancies among black and white Americans in the Collaborative Perinatal Study and dental casts from their children at the age of 6-12 years were studied to determine the effect of maternal smoking on permanent tooth crown dimensions. A trend of reduction, similar to that observed in the deciduous second molars, was found in the permanent first molars and also in the mesio-distal dimension of permanent incisors in relation to sex and race of the children and smoking habits of the mother. In terms of peak in their mitotic growth, the results can be interpreted to indicate a sensitive period of intra uterine development from the 24th to 28th gestational weeks. Comparisons of postnatal body size and differential correlation patterns in affected tooth dimensions with early postnatal body and head size between smokers and non-smokers, suggests that maternal smoking during pregnancy may have an effect on basic growth of the head and body and/or the developmental process that impacts tooth development at some specific sensitive period also during the postnatal formation of these tooth crowns.
Modifications to the Gustafson method of age estimation from teeth are described. They are designed to minimise the subjective nature of the scoring technique and to quantify the regressive changes in the enamel, dentine and cementum. Randomly selected teeth from 25 Indians were examined by the Gustafson method and by our own modification. It was shown that our modified method resulted in more accurate and reproducible age estimations than did the original method.
In a previous paper (M. López-Nicolás et al., Forensic Sci. Int., 45 (1990) 143-150) we obtained a model of multiple regression to estimate age using computerized image analysis (IBAS) to study teeth. This method should provide more precise measurements of the parameters involved and to test this hypothesis we have carried out a blind study using more than one tooth from the same individual in order to check the diagnostic accuracy of the method. Our results show that individual variability introduced serious errors in tooth age estimation using computerized image analysis. However the study of more than one tooth per individual improves the accuracy of age estimation. Specific cases should therefore be interpreted cautiously, as a degree of variability can be expected using the parameters defined in this method.
The literature on tooth formation in children with cleft lip and/or palate is reviewed. The main focus of interest is the association of cleft type and dental abnormalities in number, size, shape, timing of formation, and eruption and cause of the abnormalities. The upper lateral incisor is the most susceptible to injury in the area of cleft in both deciduous and permanent dentitions. This tooth is affected in most instances, even in the cases of microforms of the cleft lip. The prevalence of hypodontia increases strongly with the severity of cleft. More teeth are congenitally missing from the upper jaw than from the lower jaw; however, in the permanent dentition both jaws are affected. Very high prevalence of hypodontia are observed in connection with the Van der Woude syndrome associated with cleft and with the Pierre Robin anomaly. Hypodontia is similarly prevalent in subjects with isolated cleft palate with and without a positive family history of clefts. The prevalence of hypodontia varies largely in different populations. Asymmetric formation of the contralateral teeth is a milder form of hypodontia. The prevalence of asymmetrically developing pairs of teeth is far more common in children with clefts than in children with normal palates or lips. In the permanent dentition the timing of tooth formation is delayed in children from all cleft groups compared to noncleft children. The delay lengthens (with increasing severity of cleft) from 0.3 to 0.7 years and is similar in all permanent teeth in both jaws. In children with hypodontia, the delay is still more severe. As the child becomes older, the delay may increase.(ABSTRACT TRUNCATED AT 250 WORDS)
Two current methods to assess spacing-crowding among lower anterior teeth are described and contrasted. These are the anterior space analysis of Merrifield and the irregularity index of Little. There is only a modest correlation between these methods (rs = +0.53) because they provide complementary information; space analysis is more attuned to tooth displacements while the irregularity index is susceptible to axiversions. Cases illustrating major divergences between the two methods are illustrated.
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The present study was undertaken to examine whether excessive proclination of mandibular incisors results in gingival retraction. In patients with surgically treated mandibular prognathism, 29 with more than 10 degrees proclination of mandibular incisors and 33 with minimal change in incisor inclination during presurgical orthodontic phase were selected. A total of 21 and 19 patients, respectively, could meet for a clinical follow-up examination including Visible Plaque Index, Gingival Bleeding Index, probing pocket depth, and length of supracrestal connective tissue attachment. Study models and intraoral color slides were also made. The mean postoperative times at this examination were 7.8 (SD 2.5) and 8.1 (SD 2.8) years, respectively. Clinical crown height was measured on the study models taken before and after appliance therapy, at the 3-year postoperative control (check) and at the follow-up examination. The number of teeth with recession was determined from the color slides taken at the same intervals; the thickness of the symphysis was measured on the cephalograms taken before treatment. The results demonstrated significantly more increase in clinical crown height and significantly more teeth developing recession both during appliance therapy and during the period from removal of appliance to the 3-year postoperative control in the patients with excessive proclination than in the patients with minimal change in incisor inclination. The correlation coefficient between width of symphysis and increase in clinical crown height in patients with excessive proclination was statistically significant. Only minimal changes were observed from 3 years postoperatively to the follow-up examination. No differences in clinical measurements were observed between the groups and bone dehiscences were not found.
This article discusses the quantitative effects of angulation of incisors on dental arch length. The incisors are approximated mathematically to rectangular shapes, which enables the authors to calculate the change in arch length when teeth are tipped and to describe graphically the effect of other influencing parameters. The authors demonstrate that the height and the width of a tooth crown can enhance or diminish the effect of angulation on arch length. In addition to angulation, dental arch length is also influenced by torque. A mathematic formula has been derived and the results are demonstrated numerically and graphically. The authors show that vertical positioning of the brackets plays an important role because torquing is a rotational movement around the center of the bracket slot. Hence, in calculating the effect of torque on dental arch length, one must consider different angles and axes than those discussed by Andrews.4 The interaction between angulation and inclination and its influence on dental arch length has been investigated. It has been found to cause little change in arch length.