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Timing and sequence of eruption of permanent teeth in a longitudinal sample of children from Oregon
A R T IC L E S
Timing and sequence of eruption of permanent teeth in a longitudinal sample of children from Oregon Bhim Sen S avara, DMD, M S John C. Steen, PhD, Portland, Ore
tion of human permanent teeth in clude that of Stone and others,12 a three-year study of subjects from the National Children’s Home in En gland; the survey of nine years of annual dental records on 50 boys and 50 girls from the Cleveland public schools by Fulton and P rice13; Nanda’s 14 report on chil dren from the Child Research Coun cil longitudinal growth study in Denver; and the work of Meredith and his co-workers15,16 on children from Iowa.
Materials and methods A longitudinal sam ple of children was exa m in ed fo r timing and seq u en ce of eruption of p erm an en t teeth. S ep ara te consideration was given to 124 boys a nd 163 girls from the Child Study Clinic longitudinal growth study. Girls show m ore variability in a g e at eruption than boys, and eruption is gen era lly ea rlier in girls. The d e g re e o f variation in seq u en ces of eruption of the first seven p erm a n en t teeth is distinct. The most common seq u en ce in g irls’ m axillas occu rred in only 11.4% o f subjects; in boys, the most common seq u en ce a p p ea red in 13.4% o f subjects. Predictability efficien cy of eruption of the first three p erm a n en t teeth is not h ig h er than 0.74.
T
J L he timing and sequence of eruption of permanent teeth (ex cluding the third molar) in a lon gitudinal sample of children from Oregon were determined. The study has been in progress for more than 25 years.1'6 Current standards of eruption of teeth are made mostly on the basis of cross-sectional studies. Usually, large heterogenous samples of a population are used, and each child is examined only once. This method enables the investigators to achieve results in a short period. The find ings can then be used for comparing age of eruption with the crosssectional heterogenous norms. On the other hand, few longitud inal studies of eruption of teeth have been done. The full extent of the variation among persons during childhood can be studied only by repeated observations of the same child, preferably during the entire
period of growth. Few investigators are willing to spend 15 to 20 years to amass the records that would in clude radiographs, study casts, and six-month oral examinations. How ever, the results are very worth while. A longitudinal approach was the preferred method for this study. The cross-sectional studies most often used as sources of norms of eruption for North American chil dren include Cohen’s7 study of 2,848 children from Minneapolis; research by Klein and others8 of 4,416 boys and girls from Hagerstown, Md; and Hurme’s9 norms derived from 24 articles about 39,000 children from Europe and North America. Recent crosssectional studies of nonwhite popu lations include those of Billewicz and McGregor10 of 635 Gambian children and that of Ballew 11 of Samoan children. Longitudinal studies of the erup
The subjects, 124 boys and 163 girls, were selected from partici pants in the longitudinal growth study of the Child Study Clinic. These children are predominantly of northwest European ancestry. The parents were of middle- and upper-middle socioeconomic classes. Most of the children lived in or near Portland, Ore. They were healthy children who received regu lar dental care. The records of ob served children range from when they were aged 3 to 28 years; how ever, material from between ages of 4 to 15 years was used for this study. Intraoral radiographs were taken every three years. The study casts and bite-wing radiographs were taken annually. Dental examina tions were conducted near succes sive anniversaries of birth and near each six-month interval between anniversaries of birth to age 14, and yearly thereafter. Eruption was defined for this study as gingival emergence. Ages of eruption, as well as missing and extracted teeth, were recorded for the first seven permanent teeth on each side of both arches. Teeth un erupted by a certain age, but listed as present at the next visit, were recorded as erupting midway be tween visits. Therefore, age at erup tion of any tooth was recorded ac curately within three months. Differences in age at eruption for homologous teeth in an arch (left and right) were either small or nonexistent; therefore, it was pracJADA, Vol. 97, August 1978 ■ 209
A RTIC LES
tical to average the age at eruption for each left and right pair.
Results NORMS OF AGE AT ERUPTION. Means and standard deviations of ages at the time of eruption of perma nent teeth are listed in Table 1. Table 2 shows percentiles of ages at erup tion. Table 1 shows that eruption oc curred earlier in girls. Though the variances were not equal (F test), they were so close that the differ ences were ignored and pooled so that a t test could be applied to the sexual differences in age of erup tion. In the maxillas, the girls were significantly earlier (at the 5% level) for all teeth except the first and sec ond molars. In the mandible, the eruptions of the lateral incisor, the canine, and the first and second premolars were significantly earlier
in the girls than in the boys. As reflected by the standard de viations in Table 1, girls generally showed more variability in age at eruption than boys, but not all teeth were significantly more variable (F test, significant at the 5% level). Five maxillary teeth were signifi cantly more variable in girls: the
central and lateral incisors, canine, and first and second premolars. The mandibular first and second molars were significantly more variable in girls. The mandibular lateral incisor showed a higher standard deviation for boys, but was not significantly more variable among boys than girls.
Table 1 ■ Age at eruption (years), means, and standard deviations in 124 boys and 163 girls. Boys Mean Maxillary Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Mandibular Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar
Girls SD
Mean
SD
7.2 8.3 11.5 11.1 11.7 6.5 12.2
0.63 0.74 0.90 1.02 1.11 0.81 1.04
7.0 8.0 11.0 10.5 11.2 6.4 12.1
0.76 0.88 1.18 1.23 1.30 0.94 1.16
6.2 7.5 10.7 10.9 11.6 6.5 12.0
0.63 0.93 1.01 0.99 1.07 0.59 0.93
6.1 7.2 9.9 10.4 11.1 6.3 11.8
0.72 0.80 1.07 1.02 1.17 0.72 1.09
Table 2 ■ Percentiles of ages at eruption (years) in boys and girls. Teeth
Maxilla Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Mandible Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar
5%
25%
6.3 7.3 10.0 9.5 9.8 5.3 10.7
6.8 7.8
11.0 10.3
11.0 6.0 11.5
5.4 6.3 9.3 9.6 10.0 5.8 10.6
5.8 6.8 10.0 10.4
11.0 6.0 11.3
Boys 50% 75%
95%
5%
25%
Girls 50% 75%
95%
7.2 8.2 11.4 11.1 11.7 6.3 12.2
7.8 8.8 12.0 11.5 12.3 6.8 13.1
8.1 9.5 12.9 12.8 13.4 7.7 13.9
5.8 6.8 9.3 8.8 9.1 5.3 10.3
6.5 7.3 10.2 9.6 10.3 5.8 11.4
6.8 7.8 10.9 10.5 11.3 6.3 12.3
7.5 8.4 11.6 11.3 12.1 6.8 12.9
8.3 9.4 13.2 12.6 13.3 7.4 13.9
6.2 7.4 10.8 10.9 11.5 6.3 11.9
6.8 8.0 11.5 11.5 12.3 6.8 12.8
7.3 8.8 12.3 12.5 13.2 7.5 13.6
5.1 6.0 8.3 8.7 9.3 5.3 10.0
5.8 6.6 9.1 9.8 10.3 5.8 11.1
6.1 7.1 9.8 10.3 11.1 6.3 11.7
6.5 7.8 10.5 11.1 12.0 6.8 12.5
7.5 8.7 11.6 12.0 13.2 7.5 13.4
Table 3 ■ Sequences of tooth eruption for children from Oregon. Maxilla sequence* for girls 2-3-5-4-6-1-7 2-3-6-4-5-1-7 2-3-4-5-6-1-7 1-3-5-4-6-2-7 2-3-4-4-5-1-6 2-3-4-5-7-1-6 2-3-5-4-7-1-6 1-2-5-3-4-1-6 2-3-4-4-4-1-5 2-3-5-6-4-1-7 2-3-5-4-5-1-6 2-3-7-5-4-1-6 1-3-6-4-5-2-7 2-3-5-4-4-1-6 2-3-6-4-7-1-5 2-3-7-4-5-1-6 Unique^ Total
No. of subjectsf 12 9 9 7 5 5 5 4 4 4 3 3 2 2 2 2 27 105
Mandible sequence for girls 1-3-4-5-6-2-7 1-3-4-5-7-2-6 2-3-4-5-6-1-7 1-2-3-4-5-1-6 1-3-5-4-6-2-7 2-3-5-4-6-1-7 2-3-4-5-7-1-6 1-3-4-4-5-2-6 1-3-4-6-5-2-7 1-2-3-4-5-1-4 1-2-3-4-5-2-6 1-2-3-4-6-1-5 1-2-5-3-4-1-6 1-3-4-6-7-2-5 2-2-3-4-6-1-5 Unique Total
No. of subjects 21 9 6 5 5 5 4 3 3 2 2 2 2 2 2 24 97
Maxilla sequence for boys 2-3-6-4-5-1-7 2-3-4-4-5-1-6 1-3-4-6-5-2-7 2-3-5-4-6-1-7 2-3-4-5-6-1-7 2-3-5-4-4-1-6 2-3-5-4-6-1-6 2-3-6-4-7-1-5 1-2-5-3-4-1-6 2-3-4-4-6-1-5 2-3-4-5-5-1-6 2-3-4-5-6-1-6 2-3-4-5-7-1-6 2-3-5-4-5-1-6 2-3-5-4-7-1-6 Unique Total
No. of subjects 9 4 4 4 3 3 3 3 2 2 2 2 2 2 2 20 67
Mandible sequence for boys 1-3-4-5-6-2-7 1-3-4-5-7-2-6 1-2-3-4-5-1-6 1-3-6-4-5-2-7 2-3-4-5-6-1-7 2-3-4-5-7-1-6 1-2-4-5-6-3-7 1-3-4-4-5-2-6 1-3-5-4-7-2-6 2-3-4-4-5-1-6
Unique Total
•Sequence: central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar. ^Includes only dentitions with all seven teeth present in each quadrant. ^Sequences that occurred only once in the group. 210 ■ JADA, Vol. 97, August 1978
No. of subjects 9 6 4 4 4 4 2 2 2 2
30 69
A RTICLES
Table 4 ■ Percentage of times each tooth* appeared in given position in eruption sequence. Times Mandible First Second Third Fourth Fifth Sixth Seventh Most likely sequence Maxilla First Second Third Fourth Fifth Sixth Seventh
11
12
73 26 1 0 0 0 0
2 22 75 1 0 0 0
1
3
24 75 1 0 0 0 0
0 12 87 0 1 0 0
Girls C PI N=97 0 0 1 0 20 4 56 39 21 48 3 7 0 1 4
5
P2
Ml M2*
11
12
0 0 1 10 21 51 18
42 57 1 0 0 0 0
0 0 0 3 13 35 48
71 29 0 0 0 0 0
0 25 75 0 0 0 0
6
2
7
1
3
N=105 0 0 0 0 3 10 30 63 41 23 20 4 7 1
Boys PI =69 0 0 1 1 16 9 61 33 12 46 9 9 1 1 C
4
5
N-=67 0 0 0 0 0 7 37 66 24 30 28 1 4 1
P2 0 0 0 16 30 32 22 5 or 6
Ml M2* 48 48 4 0 0 0 0 1 or 2
0 0 1 7 16 42 33 6 or 7
0 85 0 19 0 90 0 0 0 13 0 81 10 10 0 0 1 1 0 0 1 90 1 0 20 0 5 0 0 0 7 16 31 1 11 0 0 0 39 18 34 0 38 0 42 0 33 0 13 0 46 0 0 31 0 10 5 6 5 Most likely sequence 2 3 4 4 or or 1 2 3 4 4 1 6 or 6 7 6 Vertical totals may range from 99% to 103% of N because of small cumulative rounding error. Range of horizontal totals reflects ties. •Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar.
Table 5 ■ Correlations for permanent teeth* erupting in early and late childhood.
Boys
Girls
Independent variable(s) 11 12 Ml 11, 12 11, Ml 12, Ml 11, 12, Ml 11 12 Ml 11, 12 11, Ml 12, Ml 11, 12, Ml
C .71 .64 .41 .73 .73 .67 .74 .58 .55 .44 .61 .60 .60 .64
Maxillary arch P2 M2 PI .63 .58 .42 .50 .46 .29 .37 .34 .36 .63 .58 .42 .65 .59 .47 .54 .50 .40 .65 .60 .47 .68 .57 .61 .61 .51 .53 .49 .44 .58 .71 .59 .63 .70 .60 .69 .67 .58 .67 .73 .62 .70
Mandibular arch C PI P2 M2 .49 .51 .65 .58 .49 .56 .64 .51 .37 .25 .48 .60 .53 .59 .70 .60 .50 .51 .67 .70 .53 .56 .69 .67 .54 .59 .72 .68 .61 .56 .58 .62 .67 .62 .55 .61 .62 .67 .59 .72 .69 .64 .61 .66 .66 .67 .63 .73 .70 .70 .62 .73 .71 .70 .64 .74
•Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, second molar.
VARIETY IN SEQUENCE OF ERUP TION. An interesting finding from this study was the extent of the variation that occurred in sequences of eruption of the first seven permanent teeth. The variety in the sequence of erup tion is illustrated in Table 3, in which the position in the array of numbers indicates the tooth and the number indicates the order of erup tion of that tooth. Teeth that erupted at the same time were given the same number. Only those sub jects who had all seven teeth erupted were included. The most common maxillary se quence in girls is 2-3-5-4-6-1-7. (Po sition designates the tooth and the number designates the order.) This means that the central incisor is the second tooth to erupt, the lateral in-
Max II
Max 12
Max Ml
----- Boys ----- Girls
Mand I I
Mand 12
Mand Ml
Fig 1 ■ Comparison of relative position in order of eruption for three early permane teeth in boys and girls. Savara-Steen : TIMING, SEQUENCE OF ERUPTION OF PERMANENT TEETH ■ 211
A R TIC LES
Max
C
Max PI
Max P2
Max M2
Mand P2
Mand M2
------- Boys ------- Girls
Mand C
Mand PI
Fig 2 ■ Comparison of relative position in order of eruption for four later permanent teeth in boys and girls.
cisor is the third tooth to erupt, the canine is the fifth tooth to erupt, and so on. However, this most common sequence in the girls’ maxillas occurs in only 12 of 105 subjects, or 11.4%. In the boys’ maxillas, this same sequence ties with two others as the second most common, but occurs in only four of 67 subjects, or 5.9%. The most common sequence in boys (2-3-64-5-1-7) occurs in nine of 67 sub jects, or 13.4%, whereas this same sequence occurs in nine of 105 girls (the second most frequent), or 8.6%. The most common mandibular se quence for girls occurs in 21 of 97 subjects, or 21.6%, and the most common sequence for boys occurs 212 ■ JADA, Vol. 97, August 1978
in nine of 69 subjects, or 13%. For each of the four groups in Table 3, the sum of the unique sequences (that is, sequences that only one subject in each group has) makes up a high percentage of the total varia tion. In girls’ maxillas, unique se quences occur in 27 of 105 of the subjects, or about 25.7%. They occur in approximately 29.9% of the girls’ mandibles and approximately 24.7% and 43.5% in the boys’ man dibles and maxillas, respectively. Thus far, the variability in erup tion sequences has been stressed. To balance the scale, Table 4 shows that for each jaw and for each sex a particular tooth is more likely to erupt in one certain rank (that is,
first, second, third, and so on) in the sequence of eruption than in another rank. For example, in the girls’ mandibles, the central incisor was first 71 times in 97 subjects. The lateral incisor was third 73 of 97 times. The canine was fourth 54 times. The first premolar was most often fifth, the second premolar was most often sixth, and the first molar was usually last to erupt. This indi cates that the most common se quence of eruption for girls’ mandi bles is 1-3-4-5-6-2-7. Table 3 con firms this. Thus, Table 4 illustrates that certain sequences of eruption can be more commonly expected than others. The danger in acknow ledging this is in extending this generality as is commonly done in clinical decisions. Table 4 also shows that there are some differences according to sex in the percentage of timeg each tooth was in a given position in the erup tion sequence. The differences and similarities are more graphically apparent in Figures 1 and 2. Figure 1 shows the comparisons between sexes of the three earliest erupted teeth of boys and girls (the central incisor, lateral incisor, and first mo lar), and Figure 2 illustrates the comparisons between sexes of the four later erupting teeth (the canine, first premolar, second premolar, and second molar). Similarities are stronger for the early teeth, except for the mandibular first molar (Fig 1). Differences are greater for the later erupting teeth, except for the mandibular canine and both the maxillary and mandibular first premolar. Boys, particularly, show more variation in the relative order of eruption than do girls for the second premolar, first molar, and second molar in the mandible and for the canine and second molar in the maxilla. P R E D IC T A B IL IT Y
OF
E R U PT IO N .
Table 5 gives correlations among the first three permanent teeth (and com binations of them) to appear (the central incisor, lateral incisor, and first molar). The correlations were generally not very high; only a few (19 of 112) were 0.70 or higher. The
A RTICLES
T a b le
6 ■ Most frequent eruption sequences (II, 12, C, PI, P2, Ml, M2*). Oregon children
First Maxilla Girls
2-3-5-4-6-1-7 (12/105, 11%) 2-3-6-4-5-1-7 (9/67, 13%)
Boys Both sexes Mandible Girls Boys Both sexes Second Maxilla Girls
Boys
Both sexes Mandible Girls Boys Both sexes Third Maxilla Girls Boys
Both sexes Mandible Girls Boys
1-3-4-5-6-2-7 (21/97, 22%) 1-3-4-5-6-2-7 (9/69, 13%)
2-3-6-4-5-1-7 (9/105, 9%) 2-3-4-5-6-1-7 (9/105, 9%) 1-3-4-6-5-2-7 (4/67, 6%) 2-3-5-4-6-1-7 (4/67, 6%) 2-3-4-4-5-1-6 (4/67, 6%)
1-3-4-5-7-2-6 (9/97, 9%) 1-3-4-5-7-2-6 (6/69, 9%)
1-3-5-4-6-2-7 (7/105, 7%) 2-3-4-5-6-1-7 (3/67, 4%) 2-3-5-4-4-1-6 (3/67, 4%) 2-3-6-4-7-1-5 (3/67, 4%) 2-3-5-4-6-1-6 (3/67, 4%) 2-3-4-5-6-1-7 (6/97, 6%) 1-2-3-4-5-1-6 (4/69, 6%) 1-3-6-4-5-2-7 (4/69, 6%) 2-3-4-5-6-1-7 (4/69, 6%) 2-3-4-5-7-1-6 (4/69,6%)
Both sexes
Denver children!
2-3-5-4-6-1-7
I .3.4.5. 6-2-7
2-3-6-4-5-1-7
Iowa children^:
2-3-5-4-6-1-7 (26% of boys)
1-3-5-4-6-2-7 (18%) 1-3-4-5-6-2-7
2-3-6-4-5-1-7 (235 of boys)
I .3. 4.5.6-2-7 2-3-4-5-6-1-7
2-3-5-4-7-1-6
1-3-4-5-7-2-6 2-3-4-5-7-1-6
•Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar. fAfter Nanda.14 iAfter Sturdivan and others15 and Knott and Meredith.16
highest was 0.74 and the lowest was 0.29. Except for correlations with the second molar in the girls’ man dibles, prediction efficiency was not appreciably increased by using more than one independent variable.
D iscussion NORM S
OF
AGE
AT
ERU PTIO N .
The average ages at eruption for the 14 permanent teeth, as shown in Table 1, are not in themselves un
usual. It is not surprising to find that the standard deviations are gener ally smaller than those of Hurme’s9 study or other similar cross-section al studies of large populations that have long been used as sources of standards of eruption. Norms or standards must be established for as many local populations as pos sible for anthropological use in com paring regionally or culturally di verse groups. The amount that can be learned of subtle differences and
their causes in populations is in correlation with the number of standards that are made available for localized populations. Data from homogeneous populations are also desirable for clinical discrimination of significant early or late eruption. Tracy and others17 described consis tently early eruption in five chil dren in Oregon having precocious puberty. The precocity of the erup tion of teeth was not apparent when viewed in the light of current clini cal eruption norms, but it was obvi ous in comparison with the stan dards of tooth eruption of children from Oregon described in a pre liminary study.18 Two of the better previous studies of North American white children for age at eruption of permanent teeth are those of Nanda14 and Knott and Meredith.16 Their sample de scriptions (except size) and methods of assessing age at erup tion are comparable to this study. Nanda reported the median ages at eruption of children from Denver, and Knott and Meredith reported the mean ages at eruption of chil dren from Iowa. When Nanda’s fig ures were compared with this study, it was found that the chil dren from Oregon generally showed eruption of their permanent teeth earlier than did the children from Denver. The average difference be tween Denver medians and Oregon medians was 0.29 years with a range from —0.1 (boys’ maxillary first premolar) to +0.5 (five teeth) years. The children from Iowa had mean ages of tooth eruption averag ing 0.24 years earlier than the mean eruption ages of the children from Oregon. The differences for 28 means ranged from 0 (girls’ maxil lary second premolar) to 0.6 (two teeth) years. Standard deviations were comparable. Tables 1 and 2 show that Oregon means exceed Oregon medians by an average of only 0.05 years. V A R IE T Y IN SEQ U EN CE O F E R U P
Another aspect of tooth erup tion that is of interest from a com parative standpoint is that of se quence of eruption. Students of anT IO N .
Savara-Steen : TIMING, SEQUENCE OF ERUPTION OF PERMANENT TEETH ■ 213
A R T IC L E S
thropology, dentistry, and forensic science are usually taught one or two sequences of the eruption of permanent teeth, perhaps based on averages of eruption from “norma tive” tables in a current text, and then the subject is dismissed. Field experience or clinical practice may ultim ately expose the student to the remarkable variability in sequences of eruption, but the literature does little to dispel the notion that there is “an eruption sequence” that de scribes this particular feature of human development. Before this study, only Nanda’s 14 report on the tooth eruption of chil dren from Denver and the study by Sturdivant and others15 of boys from Iowa have given more than a perfunctory treatment of variation in sequence of eruption found in a longitudinal sample; these discus sions were limited. Table 6 shows the first, second, and third most frequent eruption sequences for the children from Oregon and those reported for chil dren from Denver and Iowa. Per centage information is given where available. As noted previously and in Table 3, a large percentage of the children from Oregon had eruption sequences that were unique in the sample. This information of the children from Denver or Iowa was not published. In using the method of this and previous longitudinal studies of eruption, teeth erupting within three months of one another may be scored as erupting at the same age. Given the possibility of ties in the order of eruption, the combinations of eruption sequences are many. Even so, the great extent of the variability described in this study is an unexpected finding.
lar findings for the mandible were not observed. Mandibular correla tion coefficients involving the canine were low, ranging from 0.37 to 0.54 for this study. The first molar generally had the lowest cor relations with other teeth, except with mandibular second molars. Knott and M eredith16 published correlations for both boys and girls in Iowa. For girls, they found that correlations of canines or third premolars with central and lateral incisors ranged from 0.55 to 0.89; ten correlations in the mandible were 0.80 or greater. This study did not support the level of correlations found by Sturdivant and others15 and by Knott and Meredith.16
This investigation was supported in part by Grant D E 0 3 3 4 3 - 0 1 , - 0 2 , - 0 3 , National Institute of Dental Research, and Grant H D 00157-l,-2,-3 . . . -15, National Institute of Child Health and Human Development. 1. Nakamura, S.; Savara, B.S.; and Thomas, D.R. Norms of size and annual increm ents of the sphenoid bone from four to sixteen years. Angle Orthod 42 :35 Jan 1972. 2. Savara, B.S., and Singh, I.J. Norms of size and annual increm ents of seven anatomical measures of m axillae in boys from three to six teen years of age. Angle Orthod 38:104 April 1968. 3. Savara, B.S., and Tracy, W.E. Norms of size and annual increm ents for five anatom i cal measures of the m andible in boys from three to sixteen years of age. Arch Oral Biol 12:469 April 1967. 4. Sekiguchi, T.; Savara, B.S.; and Arya, B.S. Norms of size and annual increm ents of six anatom ical measures o f the cranium in boys and girls from four to fifteen years of age. Am J Phys Anthropol 39:49 July 1973. 5. Singh, I.J., and Savara, B.S. Norms of size and annual increm ents of seven anatomical
TH E AU TH O RS
P R E D IC T A B IL IT Y
OF
measures of m axillae in girls from three to six teen years of age. Angle Orthod 36:312 Oct 1966. 6. Tracy, W.E., and Savara, B .S. Norms of size and annual increments of five anatom ical measures of the mandible in girls from 3 to 16 years of age. Arch Oral Biol 11:587 June 1966. 7. Cohen, J.T. The dates of eruption of the permanent teeth in a group of M inneapolis children: a prelim inary report. JADA 15:2337 Dec 1928. 8. Klein, H.; Palmer, C.E.; and Kramer, M. Studies on dental caries. The use of the nor mal probability curve for expressing the age distribution of eruption of the permanent teeth. Growth 1:385, 1937. 9. Hurme, V.O. Ranges of norm alcy in the eruption of permanent teeth. J Dent Child 16:11 Second quarter 1949. 10. Billew icz, W.Z., and McGregor, I.A. Eruption of permanent teeth in West African (Gambian) children in relation to age, sex, and physique. Ann Hum Biol 2:117 April 1975. 11. Ballew , C.C. Eruption of permanent teeth in Sam oan children in Hawaii and West ern Samoa. Am J Phys Anthropol 44:165 Jan 1976. 12. Stone, H.H., and others. Tim e of erup tion of permanent teeth and tim e of shedding of deciduous teeth. J Br Dent Assoc 90:1 Jan 2, 1951. 13. Fulton, J.T., and Price, B. Longitudinal data on eruption and attack o f the permanent teeth. J Dent Res 33:65 Feb 1954. 14. Nanda, R.S. Eruption of human teeth. Am J Orthod 46:363 May 1960. 15. Sturdivant, J.E.; Knott, V.B.; and Meredith, H.V. Interrelations from serial data for eruption of the permanent dentition. Angle Orthod 32:1 Jan 1962. 16. Knott. V .B., and Meredith, H.V. Statis tics on eruption of the perm anent dentition from serial data for North Am erican white children. Angle Orthod 36:68 Jan 1966. 17. Tracy, W.E.; Steen, J.C.; and Klevit, H.D. Dentofacial and somatic growth in children with precocious puberty. Bull Acad Gen Dent June 1969. 18. Steen, J.C.; Tracy, W.E.; and Savara, B.S. Eruption of permanent teeth of Northwest children, abstracted. Presented at the 21st An nual M eeting of the Northwest Anthropologi cal Conference, Portland, Ore, April 1968.
^
■
ERU PTIO N .
Sturdivant and others15 found cor relation coefficients of 0.70 or greater only for boys for those correlations involving the canines. In the current study, similarly high correlation co efficients (0.70 or greater) werefound involving maxillary canines and the central incisor or combinations in volving the central incisor. In contrast to Meredith and his co-workers, sim i 214 ■ JADA, Vol. 97, August 1978
Dr. Savara is professor and chairman of the Child Study Clinic, University of Oregon Health Scien ces Center, School of Dentistry, 611 SW Campus Dr, Port land, Ore 97201. Dr. Steen is clinical assistant professor and anthropological consultant to the State M edical Examiner’s office in Oregon. Address requests for reprints to Dr. Savara. SA V A R A
ST E E N
Timing and sequence of eruption of permanent teeth in a longitudinal sample of children from Oregon Bhim Sen S avara, DMD, M S John C. Steen, PhD, Portland, Ore
tion of human permanent teeth in clude that of Stone and others,12 a three-year study of subjects from the National Children’s Home in En gland; the survey of nine years of annual dental records on 50 boys and 50 girls from the Cleveland public schools by Fulton and P rice13; Nanda’s 14 report on chil dren from the Child Research Coun cil longitudinal growth study in Denver; and the work of Meredith and his co-workers15,16 on children from Iowa.
Materials and methods A longitudinal sam ple of children was exa m in ed fo r timing and seq u en ce of eruption of p erm an en t teeth. S ep ara te consideration was given to 124 boys a nd 163 girls from the Child Study Clinic longitudinal growth study. Girls show m ore variability in a g e at eruption than boys, and eruption is gen era lly ea rlier in girls. The d e g re e o f variation in seq u en ces of eruption of the first seven p erm a n en t teeth is distinct. The most common seq u en ce in g irls’ m axillas occu rred in only 11.4% o f subjects; in boys, the most common seq u en ce a p p ea red in 13.4% o f subjects. Predictability efficien cy of eruption of the first three p erm a n en t teeth is not h ig h er than 0.74.
T
J L he timing and sequence of eruption of permanent teeth (ex cluding the third molar) in a lon gitudinal sample of children from Oregon were determined. The study has been in progress for more than 25 years.1'6 Current standards of eruption of teeth are made mostly on the basis of cross-sectional studies. Usually, large heterogenous samples of a population are used, and each child is examined only once. This method enables the investigators to achieve results in a short period. The find ings can then be used for comparing age of eruption with the crosssectional heterogenous norms. On the other hand, few longitud inal studies of eruption of teeth have been done. The full extent of the variation among persons during childhood can be studied only by repeated observations of the same child, preferably during the entire
period of growth. Few investigators are willing to spend 15 to 20 years to amass the records that would in clude radiographs, study casts, and six-month oral examinations. How ever, the results are very worth while. A longitudinal approach was the preferred method for this study. The cross-sectional studies most often used as sources of norms of eruption for North American chil dren include Cohen’s7 study of 2,848 children from Minneapolis; research by Klein and others8 of 4,416 boys and girls from Hagerstown, Md; and Hurme’s9 norms derived from 24 articles about 39,000 children from Europe and North America. Recent crosssectional studies of nonwhite popu lations include those of Billewicz and McGregor10 of 635 Gambian children and that of Ballew 11 of Samoan children. Longitudinal studies of the erup
The subjects, 124 boys and 163 girls, were selected from partici pants in the longitudinal growth study of the Child Study Clinic. These children are predominantly of northwest European ancestry. The parents were of middle- and upper-middle socioeconomic classes. Most of the children lived in or near Portland, Ore. They were healthy children who received regu lar dental care. The records of ob served children range from when they were aged 3 to 28 years; how ever, material from between ages of 4 to 15 years was used for this study. Intraoral radiographs were taken every three years. The study casts and bite-wing radiographs were taken annually. Dental examina tions were conducted near succes sive anniversaries of birth and near each six-month interval between anniversaries of birth to age 14, and yearly thereafter. Eruption was defined for this study as gingival emergence. Ages of eruption, as well as missing and extracted teeth, were recorded for the first seven permanent teeth on each side of both arches. Teeth un erupted by a certain age, but listed as present at the next visit, were recorded as erupting midway be tween visits. Therefore, age at erup tion of any tooth was recorded ac curately within three months. Differences in age at eruption for homologous teeth in an arch (left and right) were either small or nonexistent; therefore, it was pracJADA, Vol. 97, August 1978 ■ 209
A RTIC LES
tical to average the age at eruption for each left and right pair.
Results NORMS OF AGE AT ERUPTION. Means and standard deviations of ages at the time of eruption of perma nent teeth are listed in Table 1. Table 2 shows percentiles of ages at erup tion. Table 1 shows that eruption oc curred earlier in girls. Though the variances were not equal (F test), they were so close that the differ ences were ignored and pooled so that a t test could be applied to the sexual differences in age of erup tion. In the maxillas, the girls were significantly earlier (at the 5% level) for all teeth except the first and sec ond molars. In the mandible, the eruptions of the lateral incisor, the canine, and the first and second premolars were significantly earlier
in the girls than in the boys. As reflected by the standard de viations in Table 1, girls generally showed more variability in age at eruption than boys, but not all teeth were significantly more variable (F test, significant at the 5% level). Five maxillary teeth were signifi cantly more variable in girls: the
central and lateral incisors, canine, and first and second premolars. The mandibular first and second molars were significantly more variable in girls. The mandibular lateral incisor showed a higher standard deviation for boys, but was not significantly more variable among boys than girls.
Table 1 ■ Age at eruption (years), means, and standard deviations in 124 boys and 163 girls. Boys Mean Maxillary Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Mandibular Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar
Girls SD
Mean
SD
7.2 8.3 11.5 11.1 11.7 6.5 12.2
0.63 0.74 0.90 1.02 1.11 0.81 1.04
7.0 8.0 11.0 10.5 11.2 6.4 12.1
0.76 0.88 1.18 1.23 1.30 0.94 1.16
6.2 7.5 10.7 10.9 11.6 6.5 12.0
0.63 0.93 1.01 0.99 1.07 0.59 0.93
6.1 7.2 9.9 10.4 11.1 6.3 11.8
0.72 0.80 1.07 1.02 1.17 0.72 1.09
Table 2 ■ Percentiles of ages at eruption (years) in boys and girls. Teeth
Maxilla Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar Mandible Central incisor Lateral incisor Canine First premolar Second premolar First molar Second molar
5%
25%
6.3 7.3 10.0 9.5 9.8 5.3 10.7
6.8 7.8
11.0 10.3
11.0 6.0 11.5
5.4 6.3 9.3 9.6 10.0 5.8 10.6
5.8 6.8 10.0 10.4
11.0 6.0 11.3
Boys 50% 75%
95%
5%
25%
Girls 50% 75%
95%
7.2 8.2 11.4 11.1 11.7 6.3 12.2
7.8 8.8 12.0 11.5 12.3 6.8 13.1
8.1 9.5 12.9 12.8 13.4 7.7 13.9
5.8 6.8 9.3 8.8 9.1 5.3 10.3
6.5 7.3 10.2 9.6 10.3 5.8 11.4
6.8 7.8 10.9 10.5 11.3 6.3 12.3
7.5 8.4 11.6 11.3 12.1 6.8 12.9
8.3 9.4 13.2 12.6 13.3 7.4 13.9
6.2 7.4 10.8 10.9 11.5 6.3 11.9
6.8 8.0 11.5 11.5 12.3 6.8 12.8
7.3 8.8 12.3 12.5 13.2 7.5 13.6
5.1 6.0 8.3 8.7 9.3 5.3 10.0
5.8 6.6 9.1 9.8 10.3 5.8 11.1
6.1 7.1 9.8 10.3 11.1 6.3 11.7
6.5 7.8 10.5 11.1 12.0 6.8 12.5
7.5 8.7 11.6 12.0 13.2 7.5 13.4
Table 3 ■ Sequences of tooth eruption for children from Oregon. Maxilla sequence* for girls 2-3-5-4-6-1-7 2-3-6-4-5-1-7 2-3-4-5-6-1-7 1-3-5-4-6-2-7 2-3-4-4-5-1-6 2-3-4-5-7-1-6 2-3-5-4-7-1-6 1-2-5-3-4-1-6 2-3-4-4-4-1-5 2-3-5-6-4-1-7 2-3-5-4-5-1-6 2-3-7-5-4-1-6 1-3-6-4-5-2-7 2-3-5-4-4-1-6 2-3-6-4-7-1-5 2-3-7-4-5-1-6 Unique^ Total
No. of subjectsf 12 9 9 7 5 5 5 4 4 4 3 3 2 2 2 2 27 105
Mandible sequence for girls 1-3-4-5-6-2-7 1-3-4-5-7-2-6 2-3-4-5-6-1-7 1-2-3-4-5-1-6 1-3-5-4-6-2-7 2-3-5-4-6-1-7 2-3-4-5-7-1-6 1-3-4-4-5-2-6 1-3-4-6-5-2-7 1-2-3-4-5-1-4 1-2-3-4-5-2-6 1-2-3-4-6-1-5 1-2-5-3-4-1-6 1-3-4-6-7-2-5 2-2-3-4-6-1-5 Unique Total
No. of subjects 21 9 6 5 5 5 4 3 3 2 2 2 2 2 2 24 97
Maxilla sequence for boys 2-3-6-4-5-1-7 2-3-4-4-5-1-6 1-3-4-6-5-2-7 2-3-5-4-6-1-7 2-3-4-5-6-1-7 2-3-5-4-4-1-6 2-3-5-4-6-1-6 2-3-6-4-7-1-5 1-2-5-3-4-1-6 2-3-4-4-6-1-5 2-3-4-5-5-1-6 2-3-4-5-6-1-6 2-3-4-5-7-1-6 2-3-5-4-5-1-6 2-3-5-4-7-1-6 Unique Total
No. of subjects 9 4 4 4 3 3 3 3 2 2 2 2 2 2 2 20 67
Mandible sequence for boys 1-3-4-5-6-2-7 1-3-4-5-7-2-6 1-2-3-4-5-1-6 1-3-6-4-5-2-7 2-3-4-5-6-1-7 2-3-4-5-7-1-6 1-2-4-5-6-3-7 1-3-4-4-5-2-6 1-3-5-4-7-2-6 2-3-4-4-5-1-6
Unique Total
•Sequence: central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar. ^Includes only dentitions with all seven teeth present in each quadrant. ^Sequences that occurred only once in the group. 210 ■ JADA, Vol. 97, August 1978
No. of subjects 9 6 4 4 4 4 2 2 2 2
30 69
A RTICLES
Table 4 ■ Percentage of times each tooth* appeared in given position in eruption sequence. Times Mandible First Second Third Fourth Fifth Sixth Seventh Most likely sequence Maxilla First Second Third Fourth Fifth Sixth Seventh
11
12
73 26 1 0 0 0 0
2 22 75 1 0 0 0
1
3
24 75 1 0 0 0 0
0 12 87 0 1 0 0
Girls C PI N=97 0 0 1 0 20 4 56 39 21 48 3 7 0 1 4
5
P2
Ml M2*
11
12
0 0 1 10 21 51 18
42 57 1 0 0 0 0
0 0 0 3 13 35 48
71 29 0 0 0 0 0
0 25 75 0 0 0 0
6
2
7
1
3
N=105 0 0 0 0 3 10 30 63 41 23 20 4 7 1
Boys PI =69 0 0 1 1 16 9 61 33 12 46 9 9 1 1 C
4
5
N-=67 0 0 0 0 0 7 37 66 24 30 28 1 4 1
P2 0 0 0 16 30 32 22 5 or 6
Ml M2* 48 48 4 0 0 0 0 1 or 2
0 0 1 7 16 42 33 6 or 7
0 85 0 19 0 90 0 0 0 13 0 81 10 10 0 0 1 1 0 0 1 90 1 0 20 0 5 0 0 0 7 16 31 1 11 0 0 0 39 18 34 0 38 0 42 0 33 0 13 0 46 0 0 31 0 10 5 6 5 Most likely sequence 2 3 4 4 or or 1 2 3 4 4 1 6 or 6 7 6 Vertical totals may range from 99% to 103% of N because of small cumulative rounding error. Range of horizontal totals reflects ties. •Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar.
Table 5 ■ Correlations for permanent teeth* erupting in early and late childhood.
Boys
Girls
Independent variable(s) 11 12 Ml 11, 12 11, Ml 12, Ml 11, 12, Ml 11 12 Ml 11, 12 11, Ml 12, Ml 11, 12, Ml
C .71 .64 .41 .73 .73 .67 .74 .58 .55 .44 .61 .60 .60 .64
Maxillary arch P2 M2 PI .63 .58 .42 .50 .46 .29 .37 .34 .36 .63 .58 .42 .65 .59 .47 .54 .50 .40 .65 .60 .47 .68 .57 .61 .61 .51 .53 .49 .44 .58 .71 .59 .63 .70 .60 .69 .67 .58 .67 .73 .62 .70
Mandibular arch C PI P2 M2 .49 .51 .65 .58 .49 .56 .64 .51 .37 .25 .48 .60 .53 .59 .70 .60 .50 .51 .67 .70 .53 .56 .69 .67 .54 .59 .72 .68 .61 .56 .58 .62 .67 .62 .55 .61 .62 .67 .59 .72 .69 .64 .61 .66 .66 .67 .63 .73 .70 .70 .62 .73 .71 .70 .64 .74
•Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, second molar.
VARIETY IN SEQUENCE OF ERUP TION. An interesting finding from this study was the extent of the variation that occurred in sequences of eruption of the first seven permanent teeth. The variety in the sequence of erup tion is illustrated in Table 3, in which the position in the array of numbers indicates the tooth and the number indicates the order of erup tion of that tooth. Teeth that erupted at the same time were given the same number. Only those sub jects who had all seven teeth erupted were included. The most common maxillary se quence in girls is 2-3-5-4-6-1-7. (Po sition designates the tooth and the number designates the order.) This means that the central incisor is the second tooth to erupt, the lateral in-
Max II
Max 12
Max Ml
----- Boys ----- Girls
Mand I I
Mand 12
Mand Ml
Fig 1 ■ Comparison of relative position in order of eruption for three early permane teeth in boys and girls. Savara-Steen : TIMING, SEQUENCE OF ERUPTION OF PERMANENT TEETH ■ 211
A R TIC LES
Max
C
Max PI
Max P2
Max M2
Mand P2
Mand M2
------- Boys ------- Girls
Mand C
Mand PI
Fig 2 ■ Comparison of relative position in order of eruption for four later permanent teeth in boys and girls.
cisor is the third tooth to erupt, the canine is the fifth tooth to erupt, and so on. However, this most common sequence in the girls’ maxillas occurs in only 12 of 105 subjects, or 11.4%. In the boys’ maxillas, this same sequence ties with two others as the second most common, but occurs in only four of 67 subjects, or 5.9%. The most common sequence in boys (2-3-64-5-1-7) occurs in nine of 67 sub jects, or 13.4%, whereas this same sequence occurs in nine of 105 girls (the second most frequent), or 8.6%. The most common mandibular se quence for girls occurs in 21 of 97 subjects, or 21.6%, and the most common sequence for boys occurs 212 ■ JADA, Vol. 97, August 1978
in nine of 69 subjects, or 13%. For each of the four groups in Table 3, the sum of the unique sequences (that is, sequences that only one subject in each group has) makes up a high percentage of the total varia tion. In girls’ maxillas, unique se quences occur in 27 of 105 of the subjects, or about 25.7%. They occur in approximately 29.9% of the girls’ mandibles and approximately 24.7% and 43.5% in the boys’ man dibles and maxillas, respectively. Thus far, the variability in erup tion sequences has been stressed. To balance the scale, Table 4 shows that for each jaw and for each sex a particular tooth is more likely to erupt in one certain rank (that is,
first, second, third, and so on) in the sequence of eruption than in another rank. For example, in the girls’ mandibles, the central incisor was first 71 times in 97 subjects. The lateral incisor was third 73 of 97 times. The canine was fourth 54 times. The first premolar was most often fifth, the second premolar was most often sixth, and the first molar was usually last to erupt. This indi cates that the most common se quence of eruption for girls’ mandi bles is 1-3-4-5-6-2-7. Table 3 con firms this. Thus, Table 4 illustrates that certain sequences of eruption can be more commonly expected than others. The danger in acknow ledging this is in extending this generality as is commonly done in clinical decisions. Table 4 also shows that there are some differences according to sex in the percentage of timeg each tooth was in a given position in the erup tion sequence. The differences and similarities are more graphically apparent in Figures 1 and 2. Figure 1 shows the comparisons between sexes of the three earliest erupted teeth of boys and girls (the central incisor, lateral incisor, and first mo lar), and Figure 2 illustrates the comparisons between sexes of the four later erupting teeth (the canine, first premolar, second premolar, and second molar). Similarities are stronger for the early teeth, except for the mandibular first molar (Fig 1). Differences are greater for the later erupting teeth, except for the mandibular canine and both the maxillary and mandibular first premolar. Boys, particularly, show more variation in the relative order of eruption than do girls for the second premolar, first molar, and second molar in the mandible and for the canine and second molar in the maxilla. P R E D IC T A B IL IT Y
OF
E R U PT IO N .
Table 5 gives correlations among the first three permanent teeth (and com binations of them) to appear (the central incisor, lateral incisor, and first molar). The correlations were generally not very high; only a few (19 of 112) were 0.70 or higher. The
A RTICLES
T a b le
6 ■ Most frequent eruption sequences (II, 12, C, PI, P2, Ml, M2*). Oregon children
First Maxilla Girls
2-3-5-4-6-1-7 (12/105, 11%) 2-3-6-4-5-1-7 (9/67, 13%)
Boys Both sexes Mandible Girls Boys Both sexes Second Maxilla Girls
Boys
Both sexes Mandible Girls Boys Both sexes Third Maxilla Girls Boys
Both sexes Mandible Girls Boys
1-3-4-5-6-2-7 (21/97, 22%) 1-3-4-5-6-2-7 (9/69, 13%)
2-3-6-4-5-1-7 (9/105, 9%) 2-3-4-5-6-1-7 (9/105, 9%) 1-3-4-6-5-2-7 (4/67, 6%) 2-3-5-4-6-1-7 (4/67, 6%) 2-3-4-4-5-1-6 (4/67, 6%)
1-3-4-5-7-2-6 (9/97, 9%) 1-3-4-5-7-2-6 (6/69, 9%)
1-3-5-4-6-2-7 (7/105, 7%) 2-3-4-5-6-1-7 (3/67, 4%) 2-3-5-4-4-1-6 (3/67, 4%) 2-3-6-4-7-1-5 (3/67, 4%) 2-3-5-4-6-1-6 (3/67, 4%) 2-3-4-5-6-1-7 (6/97, 6%) 1-2-3-4-5-1-6 (4/69, 6%) 1-3-6-4-5-2-7 (4/69, 6%) 2-3-4-5-6-1-7 (4/69, 6%) 2-3-4-5-7-1-6 (4/69,6%)
Both sexes
Denver children!
2-3-5-4-6-1-7
I .3.4.5. 6-2-7
2-3-6-4-5-1-7
Iowa children^:
2-3-5-4-6-1-7 (26% of boys)
1-3-5-4-6-2-7 (18%) 1-3-4-5-6-2-7
2-3-6-4-5-1-7 (235 of boys)
I .3. 4.5.6-2-7 2-3-4-5-6-1-7
2-3-5-4-7-1-6
1-3-4-5-7-2-6 2-3-4-5-7-1-6
•Central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar. fAfter Nanda.14 iAfter Sturdivan and others15 and Knott and Meredith.16
highest was 0.74 and the lowest was 0.29. Except for correlations with the second molar in the girls’ man dibles, prediction efficiency was not appreciably increased by using more than one independent variable.
D iscussion NORM S
OF
AGE
AT
ERU PTIO N .
The average ages at eruption for the 14 permanent teeth, as shown in Table 1, are not in themselves un
usual. It is not surprising to find that the standard deviations are gener ally smaller than those of Hurme’s9 study or other similar cross-section al studies of large populations that have long been used as sources of standards of eruption. Norms or standards must be established for as many local populations as pos sible for anthropological use in com paring regionally or culturally di verse groups. The amount that can be learned of subtle differences and
their causes in populations is in correlation with the number of standards that are made available for localized populations. Data from homogeneous populations are also desirable for clinical discrimination of significant early or late eruption. Tracy and others17 described consis tently early eruption in five chil dren in Oregon having precocious puberty. The precocity of the erup tion of teeth was not apparent when viewed in the light of current clini cal eruption norms, but it was obvi ous in comparison with the stan dards of tooth eruption of children from Oregon described in a pre liminary study.18 Two of the better previous studies of North American white children for age at eruption of permanent teeth are those of Nanda14 and Knott and Meredith.16 Their sample de scriptions (except size) and methods of assessing age at erup tion are comparable to this study. Nanda reported the median ages at eruption of children from Denver, and Knott and Meredith reported the mean ages at eruption of chil dren from Iowa. When Nanda’s fig ures were compared with this study, it was found that the chil dren from Oregon generally showed eruption of their permanent teeth earlier than did the children from Denver. The average difference be tween Denver medians and Oregon medians was 0.29 years with a range from —0.1 (boys’ maxillary first premolar) to +0.5 (five teeth) years. The children from Iowa had mean ages of tooth eruption averag ing 0.24 years earlier than the mean eruption ages of the children from Oregon. The differences for 28 means ranged from 0 (girls’ maxil lary second premolar) to 0.6 (two teeth) years. Standard deviations were comparable. Tables 1 and 2 show that Oregon means exceed Oregon medians by an average of only 0.05 years. V A R IE T Y IN SEQ U EN CE O F E R U P
Another aspect of tooth erup tion that is of interest from a com parative standpoint is that of se quence of eruption. Students of anT IO N .
Savara-Steen : TIMING, SEQUENCE OF ERUPTION OF PERMANENT TEETH ■ 213
A R T IC L E S
thropology, dentistry, and forensic science are usually taught one or two sequences of the eruption of permanent teeth, perhaps based on averages of eruption from “norma tive” tables in a current text, and then the subject is dismissed. Field experience or clinical practice may ultim ately expose the student to the remarkable variability in sequences of eruption, but the literature does little to dispel the notion that there is “an eruption sequence” that de scribes this particular feature of human development. Before this study, only Nanda’s 14 report on the tooth eruption of chil dren from Denver and the study by Sturdivant and others15 of boys from Iowa have given more than a perfunctory treatment of variation in sequence of eruption found in a longitudinal sample; these discus sions were limited. Table 6 shows the first, second, and third most frequent eruption sequences for the children from Oregon and those reported for chil dren from Denver and Iowa. Per centage information is given where available. As noted previously and in Table 3, a large percentage of the children from Oregon had eruption sequences that were unique in the sample. This information of the children from Denver or Iowa was not published. In using the method of this and previous longitudinal studies of eruption, teeth erupting within three months of one another may be scored as erupting at the same age. Given the possibility of ties in the order of eruption, the combinations of eruption sequences are many. Even so, the great extent of the variability described in this study is an unexpected finding.
lar findings for the mandible were not observed. Mandibular correla tion coefficients involving the canine were low, ranging from 0.37 to 0.54 for this study. The first molar generally had the lowest cor relations with other teeth, except with mandibular second molars. Knott and M eredith16 published correlations for both boys and girls in Iowa. For girls, they found that correlations of canines or third premolars with central and lateral incisors ranged from 0.55 to 0.89; ten correlations in the mandible were 0.80 or greater. This study did not support the level of correlations found by Sturdivant and others15 and by Knott and Meredith.16
This investigation was supported in part by Grant D E 0 3 3 4 3 - 0 1 , - 0 2 , - 0 3 , National Institute of Dental Research, and Grant H D 00157-l,-2,-3 . . . -15, National Institute of Child Health and Human Development. 1. Nakamura, S.; Savara, B.S.; and Thomas, D.R. Norms of size and annual increm ents of the sphenoid bone from four to sixteen years. Angle Orthod 42 :35 Jan 1972. 2. Savara, B.S., and Singh, I.J. Norms of size and annual increm ents of seven anatomical measures of m axillae in boys from three to six teen years of age. Angle Orthod 38:104 April 1968. 3. Savara, B.S., and Tracy, W.E. Norms of size and annual increm ents for five anatom i cal measures of the m andible in boys from three to sixteen years of age. Arch Oral Biol 12:469 April 1967. 4. Sekiguchi, T.; Savara, B.S.; and Arya, B.S. Norms of size and annual increm ents of six anatom ical measures o f the cranium in boys and girls from four to fifteen years of age. Am J Phys Anthropol 39:49 July 1973. 5. Singh, I.J., and Savara, B.S. Norms of size and annual increm ents of seven anatomical
TH E AU TH O RS
P R E D IC T A B IL IT Y
OF
measures of m axillae in girls from three to six teen years of age. Angle Orthod 36:312 Oct 1966. 6. Tracy, W.E., and Savara, B .S. Norms of size and annual increments of five anatom ical measures of the mandible in girls from 3 to 16 years of age. Arch Oral Biol 11:587 June 1966. 7. Cohen, J.T. The dates of eruption of the permanent teeth in a group of M inneapolis children: a prelim inary report. JADA 15:2337 Dec 1928. 8. Klein, H.; Palmer, C.E.; and Kramer, M. Studies on dental caries. The use of the nor mal probability curve for expressing the age distribution of eruption of the permanent teeth. Growth 1:385, 1937. 9. Hurme, V.O. Ranges of norm alcy in the eruption of permanent teeth. J Dent Child 16:11 Second quarter 1949. 10. Billew icz, W.Z., and McGregor, I.A. Eruption of permanent teeth in West African (Gambian) children in relation to age, sex, and physique. Ann Hum Biol 2:117 April 1975. 11. Ballew , C.C. Eruption of permanent teeth in Sam oan children in Hawaii and West ern Samoa. Am J Phys Anthropol 44:165 Jan 1976. 12. Stone, H.H., and others. Tim e of erup tion of permanent teeth and tim e of shedding of deciduous teeth. J Br Dent Assoc 90:1 Jan 2, 1951. 13. Fulton, J.T., and Price, B. Longitudinal data on eruption and attack o f the permanent teeth. J Dent Res 33:65 Feb 1954. 14. Nanda, R.S. Eruption of human teeth. Am J Orthod 46:363 May 1960. 15. Sturdivant, J.E.; Knott, V.B.; and Meredith, H.V. Interrelations from serial data for eruption of the permanent dentition. Angle Orthod 32:1 Jan 1962. 16. Knott. V .B., and Meredith, H.V. Statis tics on eruption of the perm anent dentition from serial data for North Am erican white children. Angle Orthod 36:68 Jan 1966. 17. Tracy, W.E.; Steen, J.C.; and Klevit, H.D. Dentofacial and somatic growth in children with precocious puberty. Bull Acad Gen Dent June 1969. 18. Steen, J.C.; Tracy, W.E.; and Savara, B.S. Eruption of permanent teeth of Northwest children, abstracted. Presented at the 21st An nual M eeting of the Northwest Anthropologi cal Conference, Portland, Ore, April 1968.
^
■
ERU PTIO N .
Sturdivant and others15 found cor relation coefficients of 0.70 or greater only for boys for those correlations involving the canines. In the current study, similarly high correlation co efficients (0.70 or greater) werefound involving maxillary canines and the central incisor or combinations in volving the central incisor. In contrast to Meredith and his co-workers, sim i 214 ■ JADA, Vol. 97, August 1978
Dr. Savara is professor and chairman of the Child Study Clinic, University of Oregon Health Scien ces Center, School of Dentistry, 611 SW Campus Dr, Port land, Ore 97201. Dr. Steen is clinical assistant professor and anthropological consultant to the State M edical Examiner’s office in Oregon. Address requests for reprints to Dr. Savara. SA V A R A
ST E E N