Timing and sequence of eruption of permanent teeth in a longitudinal sample of children from Oregon

Association between Eruption Sequence of Posterior Teeth, Dental Crowding, Arch Dimensions, Incisor Inclination, and Skeletal Growth Pattern

Background: We conducted research to investigate the effects of the eruption sequence of posterior teeth, arch dimensions, and incisor inclination on dental crowding. Material and Methods: A cross-sectional analytic study was performed on 100 patients (54 boys and 46 girls; mean ages: 11.69 and 11.16 years, respectively). Seq1 (canine-3-/second premolar-5-) or Seq2 (5/3) eruption sequences were recorded in maxilla, and Seq3 (canine-3-/first premolar-4-) or Seq4 (4/3) eruption sequences in mandible; tooth size, available space, tooth size-arch length discrepancy (TS-ALD), arch lengths, incisor inclination and distance, and skeletal relationship were noted. Results: The most common eruption sequences in the maxilla and mandible were Seq1 (50.6%), and Seq3 (52.1%), respectively. In the maxilla, posterior tooth sizes were larger in crowded cases. In the mandible, anterior and posterior tooth sizes were larger in crowded patients. No relationship between incisor variables and the maxillo-mandibular relationship and dental crowding was found. A negative correlation between inferior TS-ALD and the mandibular plane was found. Conclusions: Seq1 and Seq 2 in the maxilla and Seq 3 and Seq 4 in the mandible were equally prevalent. An eruption sequence of 3–5 in the maxilla and 3–4 in the mandible is more likely to cause crowding.

Three-Dimensional Analysis of the Pulp Chamber and Coronal Tooth of Primary Molars: An In Vitro Study

The anatomical variability of primary molars promotes research to improve clinical restorative activity, forensic identification, and industrial development. The objective was to study the morphology of the pulp chamber and its three-dimensional relationship with the external morphology of the tooth. A total of 151 deciduous molars were collected and subjected to three-dimensional imaging analysis in order to determine dental crown (CV) and pulp chamber (PV) volumes, their ratio (VR), pulp chamber roof (PCR) and pulp chamber floor (PCF) area, the furcation length (FD), and morphological peculiarities. The data were compared using the Kruskal–Wallis test in SPSS 26 software. The statistical analysis determined statistically significant differences between the four groups of molars for all variables. Great anatomical variability was observed, especially in the maxillary first molar, the volumes were higher in the maxillary second molar and the highest risk of furcal perforation was seen in the mandibular first molar. Additionally, mandibular second molars with six pulp horns, and some different density images compatible with accessory canals and pulp stones were found. Based on the findings of this investigation, we confirm the great anatomical variability that exists between the maxillary and mandibular molars.

Artificial intelligence-aided detection of ectopic eruption of maxillary first molars based on panoramic radiography

OBJECTIVES

Ectopic eruption (EE) of maxillary permanent first molars (PFMs) is among the most frequent ectopic eruption, which leads to premature loss of adjacent primary second molars, impaction of premolars and a decrease in dental arch length. Apart from oral manifestations such as delayed eruption and discoloration of PFMs, panoramic radiography can reveal EE of maxillary PFMs as well. Identifying eruption anomalies in radiographs can be strongly experience-dependent, leading us to develop here an automatic model that can aid dentists in this task and allow timelier interventions.

METHODS

Panoramic X-ray images from 1480 patients aged 4-9 years old were used to train an auto-screening model. Another 100 panoramic images were used to validate and test the model.

RESULTS

The positive and negative predictive values of this auto-screening system were 0.86 and 0.88, respectively, with a specificity of 0.90 and a sensitivity of 0.86. Using the model to aid dentists in detecting EE on the 100 panoramic images led to higher sensitivity and specificity than when three experienced pediatric dentists detected EE manually.

CONCLUSIONS

Deep learning-based automatic screening system is useful and promising in the detection EE of maxillary PFMs with relatively high specificity. However, deep learning is not completely accurate in the detection of EE. To minimize the effect of possible false negative diagnosis, regular follow-ups and re-evaluation are required if necessary.

CLINICAL SIGNIFICANCE

Identification of EE through a semi-automatic screening model can improve the efficacy and accuracy of clinical diagnosis compared to human experts alone. This method may allow earlier detection and timelier intervention and management.

Eruption Timing and Sequence of Primary Teeth in a Sample of Romanian Children

Teething is considered a significant event in the growth and development of the child by parents and especially by paediatric dentists and forensic scientists. They constantly need an “up-to-date mirror” of its variability for different geographic regions. The aims of the current study were to determine the timing and sequence of primary tooth emergence, and to establish a correlation between tooth eruption and general growth and external parameters in a sample of Romanian children. This study included 70 healthy children (53% girls and 47% boys), and the analysed data resulted from the questionnaires completed by parents during the whole process. General and specific data on primary teeth eruption were obtained. The differences between sexes were insignificant, except for the maxillary and mandibular canines (p = 0.047 and p = 0.018) and lower temporary second molars (p < 0.001), which were significantly increased in boys. The differences found between the two hemiarches were insignificant (p = 0.197). The mean age of eruption of the first tooth erupted was 7.07 ± 1.990 months. The unpaired t-test was used for comparison of the timings of eruption of the first primary teeth, according to the number of previous births and type of diet, and it was insignificant (p = 0.665 and p = 0.983 respectively).

Bayesian approach to longitudinal craniofacial growth: The Craniofacial Growth Consortium Study

Early in the 20th century, a series of studies were initiated across North America to investigate and characterize childhood growth. The Craniofacial Growth Consortium Study (CGCS) combines craniofacial records from six of those growth studies (15,407 lateral cephalograms from 1,913 individuals; 956 females, 957 males, primarily European descent). Standard cephalometric points collected from the six studies in the CGCS allows direct comparison of craniofacial growth patterns across six North American locations. Three assessors collected all cephalometric points and the coordinates were averaged for each point. Twelve measures were calculated from the averaged coordinates. We implemented a multilevel double logistic equation to estimate growth trajectories fitting each trait separately by sex. Using Bayesian inference, we fit three models for each trait with different random effects structures to compare differences in growth patterns among studies. The models successfully identified important growth milestones (e.g., age at peak growth velocity, age at cessation of growth) for most traits. In a small number of cases, these milestones could not be determined due to truncated age ranges for some studies and slow, steady growth in some measurements. Results demonstrate great similarity among the six growth studies regarding craniofacial growth milestone estimates and the overall shape of the growth curve. These similarities suggest minor variation among studies resulting from differences in protocol, sample, or possible geographic variation. The analyses presented support combining the studies into the CGCS without substantial concerns of bias. The CGCS, therefore, provides an unparalleled opportunity to examine craniofacial growth from childhood into adulthood.

Age estimation in the living: A scoping review of population data for skeletal and dental methods

Age estimation of living individuals has become a crucial part of the forensic practice, especially due to the global increase in cross-border migration. The low rate of birth registration in many countries, hence of identification documents of migrants, especially in Africa and Asia, highlights the importance of reliable methods for age estimation of living individuals. Despite the fact that a number of skeletal and dental methods for age estimation have been developed, their main limitation is that they are based on specific reference samples and there is still no consensus among researchers on whether these methods can be applied to all populations. Though this issue remains still unsolved, population information at a glance could be useful for forensic practitioners dealing with such issues. This study aims at presenting a scoping review and mapping of the current situation concerning population data for skeletal (hand-wrist and clavicle) and dental methods (teeth eruption and third molar formation) for age estimation in the living. Two hundred studies on the rate of skeletal maturation and four hundred thirty-nine on the rate of dental maturation were found, covering the period from 1952 and 2020 for a total of ninety-eight countries. For most of the western and central African countries there are currently no data on the rate of skeletal and dental maturation. The same applies to the countries of the Middle East, as well as the eastern European countries, especially as regard the skeletal development.

Permanent tooth emergence: Timing and sequence in a sample of Black Southern African children

OBJECTIVES

This study investigates mean age, sequence, and temporal trends of permanent tooth emergence in Black Southern African children and compares the findings with other population samples.

MATERIALS AND METHODS

This community-based cross-sectional study involved 639 Black Southern African children between 5 and 20 years of age. Probit analysis was used to derive the mean age at emergence of the permanent teeth. Sex and cross-population comparisons were undertaken to determine similarities and differences in emergence timing and sequence.

RESULTS

Females emerged all teeth earlier except for M3s (p < .05). Black Southern Africans have earlier mean ages of emergence compared to population samples from the USA, Europe, Australia, and Asia. Sexual dimorphism was detected in the mandibular I1/M1 emergence sequence (females, M₁ I₁ ; males, I₁ M₁ ). The sequence in males is similar in both jaws to males from other sub-Saharan African, USA, and European samples. Females show a similar sequence pattern in the maxilla with other sub-Saharan African, and also Australian and US females of European ancestry. There is a high frequency of polymorphism in the P1P2C1 emergence sequence, with significantly more P2P1C1 maxillary sequences seen among males. Polymorphic variation was common for the I₁ M₁ sequence in both males and females.

DISCUSSION

Mean age of tooth emergence among Black Southern African children is similar to children from most other sub-Saharan African populations. No temporal change was seen in the mean age of emergence. Earlier permanent tooth emergence in Black Southern Africans is part of a general sub-Saharan pattern that is distinct from European and Asian populations.

Standards for permanent tooth emergence in Czech children

Background

The aim of this study is to develop a population-specific reference for permanent tooth emergence among 4–15 years old Czech Republic children. The reference derived from this sample population are essential for pediatric dental diagnostics, orthodontic treatment planning, as well as anthropological and forensic applications.

Methods

In this cross-sectional epidemiological survey, dental examinations of 1,370 Czech children (696 girls (50,8%) and 674 boys (49,2%), whose parents or legal guardians all signed informed consent forms) from 11 elementary schools and kindergartens were performed in the classroom. During the examination, previously emerged permanent teeth (other than third molars), the child's age and gender were recorded. A tooth is defined as having erupted when at least any part of the crown penetrates the gingiva, and is clinically seen in the oral cavity. A logistic regression model was used to calculate the median emergence age per tooth for both genders and the total sample. The data was statistically processed (using IBM SPSS Statistics 23) and carried out at a deviation level of 0.05. The statistical significance of the differences in the emergence of permanent teeth (contralateral, intermaxillary, inter-gender differences) was evaluated by the McNemar test.

Results

No statistically significant differences were observed in the emergence times between right and left sides. In addition, mandibular teeth emerged earlier than the corresponding maxillary ones (with the exception of the first and second premolars). Permanent teeth were found to emerge sooner in girls. Furthermore, the greatest inter-gender difference was observed in maxillary canines.

Conclusions

The new data reported can now be used as standards when assessing permanent tooth emergence of Czech children.

Analyzing the emergence times of permanent teeth: an example of modeling the covariance matrix with interval-censored data

Based on a data set obtained in a large dental longitudinal study, conducted in Flanders (Belgium), the joint emergence distribution of seven teeth was modeled as a function of gender and caries experience on primary teeth. Besides establishing the marginal dependence of emergence on the covariates, there was also interest in examining the impact of the covariates on the association among emergence times. This allows the establishment of the preferred rankings of emergence and their dependence on covariates. To this end, the covariance matrix was modeled as a function of covariates. Modeling the covariance matrix in this way needs to ensure the positive definiteness of the covariance matrix and it is preferable that the regression parameters of the model are interpretable. The modified Cholesky decomposition of the covariance matrix, as suggested by Pourahmadi, splits up the covariance matrix into two parts where the parameters can be interpreted, given a natural ranking of the responses. This approach was used here taking into account that the emergence times are interval-censored. Hence, we opted for a Bayesian implementation of the data augmentation algorithm.

[Mean age of dental eruption in a school-age population analyzed by 2 methods]

BACKGROUND

Because dental eruption is the result of a series of physiological events, it is important to acknowledge precisely the mean age of exfoliation and eruption of each dental organ. This is useful to establish diagnostic, preventive and treatment criteria. The aim of this study was to compare the cross-sectional and cohort methods toward estimating the average age of dental eruption.

METHODS

The study sample was comprised of 524 school-age children from the State of Mexico (273 females and 251 males). Only permanent teeth were surveyed: the first upper molar and central and lateral incisors and the first lower molar. The cohort was observed during a 3-year period until the tooth budded. Dental mirror, tongue depressor and day light were used. Cross-sectional method consisted of permanent teeth observed after the first year.

RESULTS

In both methods, teeth budded first in females. The average ages of dental eruption according to both methods did not show statistical difference in 88% of the teeth.

CONCLUSIONS

Measurement of the age of dental eruption through cross-sectional method provides reliable data in relation to the cohort method.

Weight, height and eruption times of permanent teeth of children aged 4-15 years in Kampala, Uganda

Background

Tooth eruption is a continuous biological process by which developing teeth emerge through the jaws and the overlying mucosa to enter into the oral cavity. Tooth eruption time and sequence are important factors in dental treatment planning, particularly in orthodontics, but also in forensic dentistry to estimate age of a child. Tooth eruption time is influenced by many factors. In this study we set out to determine the timing of eruption of permanent teeth and assess its association with the height and weight of school children aged 4–15 years in Kampala, Uganda.

Methods

This was a cross sectional study comprising of 1041 healthy Ugandan children: boys/girls (520/521) who were consecutively selected from two primary schools in Kampala. The children were clinically assessed for tooth emergency through the oral mucosa as well as measuring their weight and height. The mean and standard deviation of tooth eruption time was estimated for boys and girls. Bivariate analysis was used to assess any significant association between tooth eruption time and demographic variables. Pearson and partial correlation analyses were used to assess any significant association between the tooth eruption time and anthropometric measurements of the children.

Results

Generally, the mean eruption times for girls were lower compared to boys except for three teeth (#25, #32 and #42) which erupted earlier in boys. The average difference in mean eruption times of all teeth between boys and girls was found to be 0.8 (range, 0–1.5) years. In partial correlation analysis, mean tooth eruption times were positively, but not significantly associated with height while controlling for weight except for the mandibular left central incisor (#31). On the other hand, in partial correlation analysis, mean tooth eruption times were positively associated with weight while controlling for height except for tooth #11, #16, #26 and #41. The weight of the child was significantly correlated with mean eruption times in 50% of the teeth.

Conclusion

In the present study, the mean tooth eruption times for girls were lower compared to boys except for three teeth (#25, #32 and #42). The height of the child did not show any significant influence on the tooth eruption times while the influence of weight on tooth eruption times was non-conclusive.

A prospective cohort study on emergence of permanent teeth and caries experience in Korean children

OBJECTIVES

The objectives of this study were to investigate permanent tooth emergence during a 9-year longitudinal study and to assess the effect of dental caries in primary teeth on the emergence of permanent teeth.

METHODS

Data on caries occurrence in primary teeth were obtained at the baseline by a trained dentist. Permanent tooth emergence data of 539 students from 16 elementary schools in Yeoncheon were examined annually from 1995 to 2003 using dental casts. The median age at emergence of the teeth was calculated using a linear logistic regression model. A multiple linear regression model was used to evaluate the effect of caries on the emergence of permanent teeth.

RESULTS

The age of permanent tooth emergence was different between boys and girls, but the difference was not statistically significant at the 5% level. Having 'decayed teeth' hastened the emergence of most second premolars and second molars, whereas the regression coefficients ranged from -1.23 to -0.82. The number of 'filled teeth' showed a correlation with maxillary second premolars and mandibular first premolar, and the regression coefficients ranged from -1.92 to -3.25.

CONCLUSIONS

Having dental caries in primary teeth can be a strong predictor of earlier emergence of permanent teeth.

Socio-demographic correlates of early childhood caries prevalence and severity in a developing country--South Africa

OBJECTIVES

To describe Early Childhood Caries (ECC) severity in South Africa and examine the association between ECC and socio-demographic factors, area-based measures of sugar consumption and water fluoride levels.

METHODS

Children, aged 36-71 months, were examined during the 1999/2002 South African National Children's Oral Health Survey (n=5822). ECC severity was described using Wyne's ECC classification (adapted) and the Significant Caries Index (SIC). Socio-demographic factors, area-based fluoride levels in water supplies, and the area-based per capita sugar expenditure obtained from the 2000 Household Expenditure Survey were examined using bivariate and multivariate analyses.

RESULTS

The mean population SiC was 7.6 and 32% presented with the severe forms of ECC. Increased per capita sugar expenditure and decreasing water fluoride levels, were significantly associated with an increased risk for any ECC, but was not significantly associated with the severe forms of ECC. Compared to blacks, being of mixed race and white were respectively associated with an increased and a decreased risk for ECC. Unemployment increased the risk for the severe forms of ECC.

CONCLUSIONS

The study findings support the implementation of an integrated primary oral health care strategy in order to address the underlying socio-economic determinants of ECC in South Africa.

Gender differences in tooth loss among Chilean adolescents: socio-economic and behavioral correlates

OBJECTIVE

To investigate gender differences in tooth loss among Chilean adolescents and its association with selected socio-economic indicators and oral-health-related behaviors.

MATERIAL AND METHODS

Data on 9,163 Chilean adolescents obtained using multistage random cluster procedures. Clinical recordings included information on missing teeth and the participants provided information on socio-demographic factors and oral-related behaviors. Two eruption-time-adjusted logistic regression analyses were used to investigate the associations between gender, tooth loss and socio-economic position/oral-health-related behaviors.

RESULTS

The association between gender and tooth loss remained after adjusting for age, eruption times in both the socio-economic position regression model and the oral-health-related behaviors model. Tooth loss followed social gradients for the variables paternal income and achieved parental education, with students reporting a paternal income < 100,000 US dollars (OR = 2.0), and having a father (OR = 1.8) and a mother (OR = 2.0) who achieved only primary school education being more likely to experience tooth loss. The adjusted regression model for behavioral indicators revealed that students who reported brushing their teeth once a day (OR = 1.6) were more likely to have experienced tooth loss than those who reported more frequent toothbrushing. Students who visited a dentist rarely (OR = 0.8) or never (OR = 0.5) were less likely to have lost first molars and/or incisors.

CONCLUSIONS

The results demonstrate that gender differences in tooth loss among young Chileans are related to socio-economic position; and selected oral-health-related behaviors after adjusting for eruption time variation.

Eruption times of permanent teeth in children and young adolescents in Athens (Greece)

In a study in Athens, Greece, during the summer of 2003, 2,304 patients (1,168 boys and 1,176 girls) were examined by a young dentistry. The examination occurred within the framework of a routine dental check-up performed at the National and Kapodistrian University of Athens. The age span ranged from 3.00 to 24.93 years of age. Sex, age and present permanent teeth were recorded. Wisdom teeth were excluded. The sequence of tooth eruption differs significantly in the lower and upper jaw, whereas no significant differences existed when comparing the sides of each jaw. The tooth eruption in the lower and upper jaw of male and female probands is symmetrical. In comparing the upper and the lower jaw of both genders, it becomes evident that there is a tendency for earlier tooth eruptions in the lower jaw. In respect to the tooth eruption sequence, a change was noted in the upper jaw. Contrary to the reports of other authors, the second premolar has changed places with the canine and erupts prior to this tooth. This could also be demonstrated in recent studies from New York and Bremen (Germany). Otherwise no major differences concerning the sequence of tooth eruptions were observed, when compared with the results gained from other populations. Concerning the entire dentition, no acceleration of the tooth eruption could be noted. The computed differences of teeth eruption as a mean value calculated over all teeth was +/-1 year at maximum, compared with studies from different continents. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation in a population of Athens revealed a change in the eruption sequence of permanent teeth. These findings are relevant for dental treatment planning and should be reconfirmed at certain intervals.

Eruption times of permanent teeth in teenage boys and girls in Izmir (Turkey)

In a study in the Aegean city of Izmir, Turkey, during the summer of 2002, 2101 patients (1046 boys and 1055 girls) were examined. The examination occurred within the framework of a dental check-up performed at two schools and one pre-school unit. The age span ranged from 3.98 to 24.91 years. Sex, age and present permanent teeth were recorded. Wisdom teeth were excluded. The sequence of tooth eruptions differs significantly in the lower and upper jaw, whereas no significant differences existed when comparing the sides of each jaw. The times of tooth eruption is earlier in females than in males. The entire tooth eruption process of the second dentition occurs in females earlier than in males. The tooth eruption in the lower and upper jaw of male and female probands is symmetrical. In comparing the upper and the lower jaw of both genders, it becomes evident that there is a tendency for earlier tooth eruptions in the lower jaw. In respect to the tooth eruption sequence, a change was noted in the upper jaw. Contrary to the reports of other authors, the second premolar has changed places with the canine and erupts prior to this tooth. Otherwise no major differences concerning the sequence of tooth eruptions, when compared to the results gained from other populations, were observed. Concerning the entire dentition, no acceleration of the tooth eruption could be noted. The computed differences of teeth eruption as a mean value calculated over all teeth, was +/- 1 year at maximum, compared to studies from different continents. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation on a population of Izmir revealed a change in the eruption sequence of permanent teeth. These findings are relevant for dental treatment planning and forensic odontology and should be reconfirmed at certain intervals.

Time and duration of eruption of first and second permanent molars: a longitudinal investigation

OBJECTIVE

The aim of this study was to investigate the variation in (i) the time (age) of eruption and (ii) the duration of the eruption of first (M1) and second (M2) permanent molar teeth. Finally, the study also provides data about the association between time of eruption of the first of the M1s and the first of the M2s.

METHODS

The study was carried out in Nexö Public Dental Health Service, Denmark. All children who, in a period of 12 months, had the first of their M1s or M2s recorded as erupted and the occlusal surface still partly covered by gingiva formed the study groups (N = 69 and 112 children, respectively). The continued eruption of all four molar teeth was recorded at recall intervals not exceeding 4 months until functional occlusion was obtained.

RESULTS

First permanent molars: eruption time--girls: from the age of 5 years and 3 months to 7 years and 8 months (mean 6.1 years); boys: from 5 years and 2 months to 7 years and 10 months (mean 6.3 years). The duration of eruption--girls: from 5 to 32 months (mean 15.4 months); boys: from 7 to 28 months (mean 15.0). Second permanent molars: eruption time--girls: from the age of 8 years and 11 months to 14 years and 4 months (mean 11.3 years); boys: from 9 years and 11 months to 13 years and 11 months (mean 12.0 years). The duration of eruption--girls: from 12 to 44 months (mean 27.1 months); boys: from 9 to 45 months (mean 27.9 months). No correlation was found between the time of eruption and the duration of eruption of M1 or M2. There was a strong positive association between the time of eruption of the M1s and the M2s (r(s) = 0.81).

CONCLUSIONS

A tremendous variation was found in time of eruption and in duration of eruption of permanent molars. This variation highlights the importance of individualizing caries preventive strategies for children.

The emergence of permanent teeth in Flemish children

The aim of the present study was to investigate the timing of emergence of permanent teeth in Flanders (Belgium). Data were obtained in the Signal-Tandmobiel projecta, a longitudinal study in a sample of 4468 Flemish children. Survival analysis with a log-logistic distribution was performed to calculate median (and mean) values and 95% CI's for all permanent teeth. The analysis indicated significantly earlier emergence ages in girls than in boys. The emergence pattern turned out to be symmetric in both sexes. Most mandibular teeth emerged significantly before their antagonists, in boys as well as in girls. These findings are in agreement with other studies on the emergence of permanent teeth.

Emergence of permanent teeth in Tanzanian children

OBJECTIVE

The aim of the present study was to investigate the emergence of permanent teeth among Tanzanian children.

METHODS

A total of 869 Tanzanian children were recruited from 16 schools in age groups 3.5-5, 6.5-8, 9.5-11 and 15-16 years of whom 428 (49%) were boys and 441 (51%) were girls. The effects of age and gender on the emergence stages of the dentition were determined for the four age groups.

RESULTS

Girls, but not boys, had some permanent maxillary canines, second premolars and mandibular and maxillary second molars as early as at the age of 6.5-8 years. Permanent teeth of both the first and the second transitional periods were already emerging at the age of 3.5-5 years and 6.5-8 years, respectively. At 3.5-5 years, 9% of the permanent teeth belonging to the first transitional period were already in occlusion. Emergence of incisors and first molars was more advanced in girls than in boys in age groups 3.5-5 and 6.5-8 years.

CONCLUSIONS

Parallel to earlier reports on different ethnic groups, the results of this study indicate that the permanent teeth of Tanzanian children erupt earlier in girls than in boys, and the mandibular teeth erupt earlier than the corresponding maxillary teeth. The difference between boys and girls was found in both the first and second transitional period. Permanent teeth in Tanzanian children clearly emerge earlier than in Caucasian children.

A longitudinal study of time trends in the eruption of permanent teeth in Danish children

The purpose was: (1) to estimate mean eruption times of permanent teeth in Danish schoolchildren for the birth cohorts from 1969 to 1982; and (2) to determine any time trends in eruption. For teeth with a low proportion of aplasia, the distribution of the eruption time was close to normal. For teeth with a higher proportion of aplasia there was a slight deviation from the normal distribution in the right-hand part of the distribution. For erupted teeth, the time to eruption was, however, again very close to the normal distribution. A small, but statistically significant, increase in mean eruption times was found for both sexes and almost all teeth. Averaged over all teeth the increase was 1.5 days per year (95% CI: 0.9--2.2) for boys and 2.6 days per year (95% CI: 2.2--2.9) for girls.

The chronology and sequence of eruption of human permanent teeth in Northern Ireland

OBJECTIVES

To ascertain the average and range of ages and sequence of eruption of human permanent teeth, taking into account the effect of premature loss of primary antecedents.

DESIGN

Longitudinal study.

SETTING

Caucasian subjects in Northern Ireland.

SAMPLE AND METHODS

Study casts at 6-monthly intervals from age 5 to 15 years of 276 children (146 males and 130 females) enrolled in the Belfast Growth Study. The mean and range of ages of eruption of each individual tooth were computed. Comparisons were made between the mean ages of eruption with and without premature loss of primary antecedents, between upper and lower arches, between right and left sides and between males and females. The sequence of eruption was also investigated.

RESULTS

The means and ranges of eruption ages are reported. Premature loss of primary antecedents delayed eruption of permanent successors except for the upper premolars which were accelerated. The differences relating to the upper first premolar and lower canine were not statistically significant. Each lower tooth erupted before its upper counterpart except for the premolars. There was no significant difference in age of eruption between right and left sides. Females tended to erupt teeth before males with the exception of the second molars in both arches; however, the only differences to reach statistical significance related to upper and lower canines and upper lateral incisors. The most frequent orders of eruption were unique to the subject. These occurred in 22% of upper and 33% of lower arches. The classic sequences: first molar-central incisor-lateral incisor-first premolar-canine-second premolar-second molar (M1-I1-I2-PM1-C-PM2-M2) in the upper arch and I1-M1-I2-C-PM1-PM2-M2 in the lower arch occurred in only 16% of upper arches and 13% of lower arches. Males adhered to the textbook sequence (20% upper, 17% lower) more than females (12% upper, 8% lower). In the upper arch of females, the order M1-I1-I2-PM1-PM2-C-M2 in 10% of subjects was almost as frequent as the classic sequence.

CONCLUSION

The ages, ranges and orders of eruption found in this study are more reliable than many which are frequently quoted on account of its longitudinal nature and the fact that the effect of premature loss of primary antecedents is taken into account. The exclusively Caucasian sample makes the data quite precise but limits applicability to patients of this ethnic origin.

Timing of eruption of permanent teeth: standard Finnish patient documents

Current standards for the eruption of teeth are constructed mostly on the basis of cross-sectional data. The aim here was to analyze the suitability of the standard patient documents created for health center dental care purposes for the collection of longitudinal data on tooth emergence. Copies of the oral health records of the 911 children born in 1970 and 1971 and in 1980 and 1981 living in three rural communities in Finland were re-examined and analyzed using a specially compiled computer program. The means and standard deviations are in line with previous results. The sex difference in emergence timing ranged from 0.1 to 1.0 years for the various teeth. The emergence of the teeth of the second phase of the mixed dentition was later in the children living in an endemic fluoride area, this difference being statistically greater for the boys than for the girls (95% Cl for differences between means was used to evaluate statistical significance). A secular trend in the eruption of permanent teeth was found between 1970 and 1980. Patient documents are shown to be suitable for the collection of longitudinal data on dental emergence.

[Individual variability in the duration of the second phase of the mixed dentition]

With a collection of dental casts from a longitudinal study of 175 orthodontically untreated probands (100 children without and 75 children with premature loss of deciduous molars and/or canines) serving as a base, the duration of the second period of mixed dentition was determined to be in relation to the probands the period of time between the gingival emergence of the first permanent buccal tooth and the full eruption of the set of teeth. The second period of mixed dentition in boys without premature loss of deciduous molars and canines lasts on an average 3.6 +/- 1.1 years and in girls 3.8 +/- 1.0 years. In cases of premature loss of deciduous molars and/or canines, the period of dentition is distinctly longer than under normal development conditions. The outside parameters (boys: Xmin = 0.9 years, Xmax = 6.2 years; girls: Xmin = 2.6 years, Xmax = 8.6 years), reflect a high degree of variability. The duration of the second period of mixed dentition is significantly affected by "the point in time of inception" and by the criteria "morphologically intact support zones" and "premature loss of deciduous molars and/or canines". Even given such data, however, it is not possible to make a sufficiently reliable prediction on an individual basis of the duration of the dentition.

Identifying normal and abnormal development of dental occlusion

Abnormalities of occlusal development manifest themselves clinically as a need for orthodontic treatment. There are many circumstances in which there is an interaction between traditional pediatric concerns and occlusal abnormalities. In some cases medical treatment impacts on the development of occlusion. In other cases, occlusal abnormalities contribute to clinical conditions seemingly far removed from the dentition.

The onset of eruption of permanent teeth amongst South African Indian children

A total of 1036 Indian children were examined to determine the mean ages of eruption for the first permanent molars, and the permanent central and lateral incisors. The youngest observed age for the eruption of any permanent tooth was 5.00 years for girls and 4.94 for boys. Mandibular teeth erupted earlier than maxillary teeth and teeth in females erupted between 1 and 6 months earlier than in males. Comparison of the results of the present study to one in South African black children showed that Indian children's teeth erupt some 3.5-7 months later than those of black children, a difference that was statistically significant.

Changes in the eruption order of the first permanent tooth and their relation to season of birth in Japan

In order to examine the eruption order of the first two permanent teeth, kindergarten children 5 to 6 years old were examined in Hakone, Japan. Among a total of 817 children examined from 1976 to 1984, 349 were determined as I-type children, whose mandibular first incisor erupted earlier than the mandibular first molar, and 183 were as M-type children, whose first molar erupted earlier in the mandible. The mandibular I-type rate, i.e., the proportion of the I-type among a total of I- and M-type children, was 66% (349/532). In 1983-1984, the I-type rate was 70% among boys and 62% among girls, but the overall I-type rate did not differ significantly by the sex of the subject or by the year of examination. The I-type rate varied significantly with the season of subject's birth. Those born in October or November showed a significantly lower I-type rate (33%) than the other subjects (P less than 0.001), in spite of a shift of birth season with low I-type rate toward winter in 1983-1984. The difference of the I-type rate according to birth season suggests that the causes responsible for this change are primarily environmental and act at the prenatal or perinatal stage of life.

The onset of eruption of the permanent dentition amongst South African black children

One thousand and twenty-four children with a mean age of 6.41 yr were examined to determine the mean ages of eruption for the first permanent molars and the permanent central and lateral incisors. The youngest observed age for the eruption of any permanent tooth amongst girls was 4.50 yr and amongst boys, 4.31 yr. The eruption ages were on the whole later than those reported in most African studies, but were very similar to those found for Kenyan African and American blacks.

Eruption pattern of permanent molars: implications for school-based dental sealant programs

Dental caries remains a prevalent, chronic disease of childhood. The preponderance of dental caries is located on the pit and fissure surfaces of teeth, an area where dental sealants are most effective in preventing this malady. In the school year 1987-88, 4,879 Ohio schoolchildren participated in an assessment of dental health. Grades chosen for this assessment included 1, 2, 3, 6, 7, 8, and 11. This study focuses on eruption of first and second permanent molars in development of a timing strategy for placement of occlusal sealants in a school-based program. An eruption score was developed for the determination of the first or second molar eruption status for each child. The data were analyzed for grade, sex, race, locale, fluoridation status, and percent of children on free or reduced-cost lunch programs. Analyses were performed on 2,215 children in grades 1-3 and 1,840 children in grades 6-8. Fifty-seven percent of first graders had all first permanent molars sufficiently erupted for sealant placement on the occlusal surface. Likewise, 23.6 percent of sixth graders had sufficient occlusal exposure on the second molar. Females showed an earlier eruption pattern than males for both first (P less than .05) and second (P less than .001) molars. Black children preceded white children only in the eruption of the second molar (P less than .001). This study provides dental public health decision makers with state-specific information on the earliest time to initiate a school-based occlusal sealant program.(ABSTRACT TRUNCATED AT 250 WORDS)

Polymorphisms in eruption sequence of permanent teeth in American children

This study provides basic descriptive data on the frequency of pairwise eruption sequences ascertained in cross-sectional examination of 6,000 black and white American children in the Ten State Nutritional Survey of 1968-1970. All sex and race groups share a distinct pattern of sequence polymorphisms in terms of location, number, and level. Teeth in eruption phase I (M1, I1, I2) rarely reverse in sequence with those in phase II (C, P1, P2, and M2). Five sequences have variants that appear at greater than or equal to 20% in all groups, with M1I1 vs. I1M1 approaching maximum polymorphic values of 50%/50%. The traditional notation for eruption sequences can be modified to reflect these important variants, giving the sequence M1 I1 I2 [P1 C P2] M2 for the maxilla and [M1 I1] I2 [C P1] [P2 M2] for the mandible. The location of major polymorphisms is explicable by close timing of teeth within phase I and, separately, teeth within phase II eruption. However, strong integration of development of physically adjacent teeth apparently acts to reduce substantially the number of sequence reversals. The Ten State Survey data provide a sound descriptive basis for two populations, yet precise comparative data are available for few other human groups or primate species.

Age and sequence of permanent-tooth emergence among Khasis

The times and emergence of permanent teeth were ascertained by examining 1,263 Khasi children (615 males and 648 females), aged 5 to 15 years. Gingival emergence of the first 28 permanent teeth was recorded and the data were subjected to probit analysis to compute the mean (and standard deviation) emergence time of each individual tooth. Tooth emergence in females was markedly earlier than in males, and canines were most advanced in this respect. Females acquired all their teeth in shorter time span (5.5 years) than males (6.5 years). There were no decisive sex differences in the sequence of tooth emergence. The differences in emergence times between antimeres were statistically nonsignificant. The length of hiatus between two active emergence dental stages was shorter for the maxilla than for the mandible. It occurred between lateral incisor and first premolar in the maxilla of both the sexes, while in case of the mandible, it was spaced between lateral incisor and canine. The Khasis showed early emergence when compared to other populations. The findings support the earlier reports that the controls of deciduous-tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.