Sequence of eruption of deciduous dentition in a Chilean sample with down's syndrome

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<ul><li><p>Pergamon PII: S0003-9969(97)00012-5 </p><p>Archs oral Biol. Vol. 42, No. 5, pp. 401-406, 1997 ~ 1997 Elsevier Science Ltd. All rights reserved </p><p>Printed in Great Britain 0003-9969/97 $1;7.00 + 0.00 </p><p>SEQUENCE OF ERUPTION OF DECIDUOUS DENTITION IN A CHILEAN SAMPLE WITH DOWN'S SYNDROME </p><p>A. ONDARZA, ~'* L. JARA, 2 P. MUNOZ ~ and R. BLANCO 2 'Department of Experimental Morphology, Faculty of Medicine, University of Chile, Casilla 70079, Santiago 7, Chile and -~Department of Cell Biology and Genetics, Faculty of Medicine, University of </p><p>Chile, Casilla 70079, Santiago 7, Chile </p><p>(Accepted 14 January 1997) </p><p>Summary--The eruption of the deciduous teeth in Down's individuals is reportedly delayed, but the extent of delay in comparison to normal children has been little studied. The eruption characteristics of the deciduous teeth in a sample of Chilean individuals with Down's syndrome were compared with those of the normal Chilean population. The sample consisted of 255 Down's individuals (all with tris- omy 21), 127 males and 128 females. Boys with Down's syndrome showed significantly delayed eruption in six teeth: in the maxilla the right central incisor and right and left lateral incisors, and in the mand- ible the right central incisor and right and left canines. Girls with Down's syndrome showed significant delays in the eruption of 11 teeth: in the maxilla the right and left lateral incisors, right and left canines and first left molar, and in the mandible the left central incisor, right and left lateral incisors and canines and second right molar. The chronological sequence of eruption in Down's children was not completely different from that of normal individuals. With a few exceptions no significant departures from Gaussian distribution were found in the age of eruption among both normal and Down's individ- uals. The variance was significantly larger in cases of Down's syndrome. 1997 Elsevier Science Ltd </p><p>Key words: deciduous teeth, sequence of eruption, Down's syndrome. </p><p>INTRODUCTION </p><p>Tooth eruption is a process that exhibits precise timing and bilateral symmetry. Genetic, systemic and environmental factors are implicated in the control of the morphogens that carry out the com- plex sequence involved in normal odontogenesis and, therefore, in dental eruption (Stewart and Poole, 1982). Biochemical studies show that during eruption, cells, proteins and enzymes change in the dental follicle, and several growth factors and pro- teins known to accelerate or retard eruption have been identified (Marks, Gorski and Wise, 1995). </p><p>Delayed eruption of systemic origin is associated with many genetics conditions such as Down's and Turner's syndromes, cleidocranial dysplasia, hemifa- cial atrophy and mucopolysaccharidosis (Smith, 1976). In Down's syndrome, eruption of the decid- uous and permanenl dentitions is delayed as com- pared with the general population (Brousseau, 1928, as cited by Cohen and Cohen, 1971; Oster, 1953; Levinson, Friedman and Stamps, 1955; Spitzer and Quilian, 1958; Cohen and Winer, 1965; Barkla, 1966; Otero and Sznadjer, 1966, Roche and Barkla, 1964, 1967; Spitzer, 1967; Orner, 1971, 1973, 1975; Cohen and Cohen, 1971; Molina, Vifias and </p><p>*To whom all correspondence should be addressed. </p><p>Garcia-Godoy, 1982; Garcia and P6rez, 1985; Fischer-Brandies, 1989; Jara et al., 1993; Roger and Coleman, 1994). Several studies report a delay in the timing and sequence of eruption of the decid- uous dentition in Down's syndrome. Levinson et al. (1955) found that in the deciduous dentition the eruption of the molars precedes that of the incisors in these individuals up to the age of 5 years. Roche and Barkla (1967), in a study of 48 Australian Down's children, found that the time of eruption of the deciduous teeth was retarded as compared to the general population, with the exception of the upper first and second molars and lower second molars. Fischer-Brandies (1989) studied the erup- tion of the deciduous dentition in 93 trisomics, ana- lysing the eruption of 842 teeth, and concluded that on average there was a delay of 6 months, the first molars being the first or second teeth to erupt. The sequence of eruption was very variable and it was impossible to establish differences between sexes or between right and left hemiarches. </p><p>In spite of the available literature, few investi- gators have documented case control observations involving rigorous statistical procedures analysing the chronology and sequence of eruption of the deciduous dentition in children with Down's syn- drome. Our objective now was to determine the pat- tern of eruption of the deciduous dentition in a </p><p>401 </p></li><li><p>402 A. Ondarza et al. </p><p>sample of Chilean individuals with Down's syn- drome and to compare it with that of the normal Chilean population. </p><p>MATERIAL AND METHODS </p><p>Down's individuals were randomly selected from the population attending Escuelas Especiales E-497, F-86 and F-296, Escuela Diferencial E-469 (state schools for mentally retarded individuals located in the South Metropolitan Area of Santiago), and Cindy College and Coocendes (private schools for handicapped children). The individuals from state schools comprised 94.12% of the sample and belonged to the same socioeconomic level; individ- uals from Cindy College and Coocendes represented 5.88% of the sample and belonged to a somewhat different socioeconomic level, but no significant statistical differences were found between the two groups. </p><p>The Down's sample consisted of 255 individuals with trisomy 21, 127 males and 128 females, with ages ranging between 4 and 84 months. The date of birth of each child was obtained from the personal records of the respective schools. The data for the normal population were obtained from a previous report by Palomino, Blanco and Cisternas (1980) which used the same clinical and statistical methods described in the present study. This sample con- sisted of 445 children (220 males and 225 females) selected from the population attending the Center for Growth and Development, North Health Area, Santiago, Chile, whose ages ranged between 1 and 72 months. The sample was divided into 14 age groups with an interval of 6 months between groups, beginning at 4 months and ending at 84 months. This division was made to enable compari- son with previous studies, especially those on the normal eruption times of the deciduous dentition in the Chilean population. </p><p>A single investigator examined the entire sample (P.M.). The examination procedure for all partici- pants was uniform: it entailed the use of a dental mirror and probe with the patient seated in a dental chair facing a window with good natural light. The survey recorded the presence or absence of teeth. A tooth was considered erupted when any portion of its crown had pierced the gum. This criterion is commonly used in tooth eruption and gives a yes- no answer which facilitates statistical analysis. </p><p>A preliminary record was made of the number of boys and girls in each group. The number of erupted teeth in each group was then recorded for each tooth, The proportion of erupted teeth in each age group was computed from these data and trans- formed into probit values by a computer program. Probit analysis is basically an iterative technique involving successive approximations to give a line of best fit as tested by least-square methods for a given series of plotted values. The program also </p><p>gives the median emergence age (the age at which eruption has occurred in 50% of the population), the SD and the SE of the estimate (Finney, 1952). The effective number needed to perform statistical anaylses was obtained by dividing the variance (SD 2) by the square of SE. The actual number of individuals in each age group cannot necessarily be used because the number must be weighted accord- ing to the amount of information. Irregular distri- butions in the proportions of erupted teeth produced very large variances and unreliable esti- mates of variables. The program identifies these as non-Gaussian distributions after a xZ-test for good- ness of fit to a normal distribution. This occurs mainly when the proportions are close to 100 or 0%. Irregular distributions were not considered further in the analysis. </p><p>The age of eruption for each tooth was compared with that of a normal population studied in the same way (Table 4). The Student t-test with Welch's correction was calculated by the difference between both means divided by the pooled SE (unknown and unequal variances). We have used Welch's correction in order to reduce the estimation errors of the degrees of freedom (Remington and Schork, 1970). The degrees of freedom were calcu- lated with the effective number. </p><p>The Student t-test was used to compare the mean for the age of eruption of each tooth between Down's and normal individuals and the F-test to compare variances between both samples; we chose significance at the 5% level. </p><p>RESULTS </p><p>Table 1 shows the age and sex distribution of the sample of Down's children. Table 2 shows the mean age of eruption (in months), with its SD and SE for each decidual tooth for boys and girls. The means with very large SEs were not considered in subsequent analyses. </p><p>Table 1. Distribution by age and sex of a sample of the Chilean population with Down's syndrome </p><p>Age (months) Boys Girls Both sexes </p><p>06 3 2 5 7-12 6 7 13 13-18 6 6 12 19-24 8 7 15 25-30 12 11 23 31 36 9 13 22 37-42 11 11 22 43 48 8 14 22 49 54 18 13 31 55 60 11 10 21 61-66 7 8 15 67-72 10 6 16 73 78 11 10 21 79 84 7 10 17 Total 127 128 255 </p></li><li><p>Down's children and deciduous teeth eruption 403 </p><p>Table 2. Means, SDs and SEs (by age in months) of erup- tion of the deciduous ~:eeth in a sample of Chilean children </p><p>with Down's syndrome </p><p>Tooth Sex x SD SE </p><p>5.5 M 127.66 5.645 2.042 F 129.12 6.067 1.838 </p><p>5,4 M 17.21 3.611 1.499 F 13.28 ** ** </p><p>5.3 M 12.02 32.10 19.48 F 30.70 6.454 1.447 </p><p>5.2 M [ 8.44 9.652 2.424 F 17.31 14.42 3.625 </p><p>5.1 M 15.27 5.515 1.797 F !5.16 9.340 4.778 </p><p>6.5 M 27.66 5.645 2.042 F 29.60 5.649 1.637 </p><p>6.4 M 17.21 3.611 1.499 F 25.87 14.34 5.253 </p><p>6.3 M 22.16 13.85 8.260 F 30.60 7.249 1.586 </p><p>6.2 M 18.13 10.01 3.422 F 17.31 14.42 3.625 </p><p>6.1 M 9.77 30.62 10.25 F 15.16 9.340 4.778 </p><p>8.1 M 14.15 11.82 3.909 F 7.515 17.75 16.02 </p><p>8.2 M 7.569 35.24 13.75 F 27.59 19.01 3.976 </p><p>8.3 M 25.87 7.667 2.046 F 27.83 11.25 2.633 </p><p>8.4 M 17.21 3.611 1.498 F 57.38 -32.74 146.18" </p><p>8.5 M 27.71 5.562 1.487 F 28.83 3.454 1.127 </p><p>7.1 M 11.07 10.76 4.288 F 12.02 7.286 2.699 </p><p>7.2 M 9.313 30.61 11.57 F 24.66 23.86 5.447 </p><p>7.3 M 2,5.65 7.431 1.906 F 23.80 10.60 2.360 </p><p>7.4 M 1'7.88 5.166 1.930 F -322.4 262.17 2939.2* </p><p>7.5 M 2'7.71 5.562 1.487 F 32.31 13.43 4.382 </p><p>*Not considered for further analysis due to large SE. **Data did not fit the Gaussian distribution </p><p>Down's girls began the eruptive sequence of decidual teeth as fol)ows: first the lower right cen- tral incisor at 7.51 months, second the lower left </p><p>contral incisor at 12.02 months, third the upper right first molar at 13.28 months, and fourth both upper right and upper left central incisors at 15.16 months. </p><p>The eruptive process of deciduous teeth in Down's boys began at 7.57 months with the lower right lateral incisor followed by the lower left lateral incisor at 9.31 months. Next came the upper left central incisor at 9.77 months and the lower left central incisor at 11.07 months. </p><p>Table 3 shows the complete chronological sequence of eruption of the deciduous teeth in Down's children. Table 4 presents the same sequence for the normal Chilean population. </p><p>Figures 1 and 2 allow better visualization of the sequence and symmetry of the pattern of eruption in normal and Down's individuals. </p><p>In normal Chilean boys the eruption pattern on the right-and left-hand sides was symmetrical both in the mandible and maxilla. In Down's boys the eruption of teeth on the two sides was asymmetrical in the maxilla, with the only excep- tion being the second molar, while in the mand- ible all the teeth presented a symmetrical pattern (Fig. 1). </p><p>Figure 2 shows that normal Chilean girls had a symmetrical eruption pattern in the maxilla and mandible. In Down's girls the pattern of eruption was asymmetrical in the maxilla for the central and lateral incisors and for the first molar. In the mand- ible the eruption pattern was symmetrical. </p><p>Figure 3 presents the significant delays in tooth eruption in Down's children as compared with nor- mal Chilean individuals. Down's girls had a larger number of teeth with significant eruption delays than Down's boys. Down's girls presented sym- metrical delays in the upper and lower lateral inci- sors and canines with respect to the right- and left- hand sides in the maxilla and the mandible. Down's boys had a symmetrical pattern of delay only for lateral incisors in the maxilla and canines in the mandible. </p><p>Table 3, Chronological sequence of eruption of the deciduous teeth in a sample of Chilean children with Down's syn- drome* </p><p>Boys - Girls </p><p>Tooth X SD Tooth k SD Tooth k SD Tooth ,~ SD </p><p>5.3 12.02 32.10 6.1 9.77 30.62 5.4 13.28 20.44 6.1 15.16 9.340 5.1 15.27 5.515 6.4 17.21 3.61l 5.1 15.16 9.340 6.2 17.31 14.42 5.4 17.21 3.611 6.2 18.13 10.01 5.2 17.31 14.42 6.4 25.87 14.34 5.2 18.44 9.652 6.3 22.16 13.85 5.5 29.12 6.067 6.5 29.60 5.649 5.5 27.66 5.645 6.5 27.66 5.645 5.3 30.70 6.454 6.3 30.60 7.249 8.2 7.569 35.24 7.2 9.313 30.61 8.1 7.515 17.75 7.1 12.02 7.286 8.1 14.15 11.82 7.1 11.07 10.76 8.2 27.59 19.01 7.2 24.66 23.86 8.4 17.21 3.611 7.4 17.88 5.166 8.3 27.83 11.25 7.3 28.80 10.60 8.3 25.87 7.667 7.3 26.65 7.431 8.5 28.83 3.454 7.5 32.31 13.43 8.5 27.71 5.562 7.5 27.71 5.562 8.4 57.38 -32.74 7.4 -322.4 262.17 </p><p>*Age in months </p></li><li><p>404 A. Ondarza et al. </p><p>Table 4. Chronological sequence of eruption of the deciduous teeth in normal Chilean population*,t </p><p>Boys Girls </p><p>Tooth J( SD Tooth J( SD Tooth J( SD Tooth J( SD </p><p>5.1 9.499 2.546 6.1 9.305 2.410 5.1 9.359 3.114 6.1 9.340 2.854 5.2 10.51 2.430 6.2 9.86 3.587 5.2 10.40 3.178 6.2 10.30 3.192 5.4 15.43 1.961 6.4 15.29 2.033 5.4 15.52 2.042 6.4 15.89 2.210 5.3 18.36 3.215 6.3 18.14 3.272 5.3 18.67 3.105 6.3 18.70 3.099 5.5 26.87 3.931 6.5 26.63 3.952 5.5 26.98 3.614 6.5 27.05 3.502 8.1 6.37 1.180 7.1 6.37 1.180 8.1 6.39 1.460 7.1 6.39 1.460 8.2 12.51 3.439 7.2 12.90 3.982 8.2 12.77 3.412 7.2 12.49 3.450 8.4 15.88 2.078 7.4 15.86 2.160 8.4 15.95 2.033 7.4 16.07 2.394 8.3 19.04 3.377 7.3 18.98 3.337 8.3 19.23 3.153 7.3 19.08 3.373 8.5 26.14 3.588 7.5 26.11 3.724 8.5 26.28 3.725 7.5 26.28 3.529 </p><p>*Age in months. tData from Palomino et al. (1980) Odontologia Chilena 28(123-124), 73 77] </p><p>According to the F-test, 39 out of 40 variances were significantly larger in the Down's sample. With the exception of the upper first right molar in girls, no significant departures from the Gaussian distribution were found in the age of eruption in normal and Down's individuals. </p><p>DISCUSSION Our results for the timing and sequence of the </p><p>pattern of eruption of the deciduous teeth in Down's children differ from tho...</p></li></ul>

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