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

Supernumerary teeth: A pictorial review and revised classification

Current literature regarding supernumerary teeth poses the risk of confusion as ambiguity in the terminology and classification of supernumerary teeth permits differing interpretations. Uncertainty in this regard distorts data on the true incidence and prevalence of supernumerary teeth. This pictorial review provides an overview of the current understanding regarding the development of supernumerary teeth, their positional and morphological classification, and eruptive alterations. We highlight the ambiguity in defining supernumerary teeth and propose an updated classification for the description of these teeth.

Development and eruption of human teeth in the Chinese population: a comprehensive dental atlas

Aim

The first comprehensive chart on dental development was published 75 years ago based on Caucasian children and this has been used as a standard dental chart to date. Few population specific charts have been developed recently and updated dental charts on modern subjects can provide more information on dental development patterns. This study aims to construct a comprehensive dental atlas for modern Chinese children and young adults to assist in clinical, forensic, and public health applications.

Methods

The study sample comprised of 2,306 subjects, age ranging from 2 to 24 years belonging to Chinese ethnicity. Dental formation and eruption of permanent teeth and resorption of primary teeth were analyzed separately for females and males. For each age range, the number of teeth (n), and the stage of development was calculated for first (Q1), second (Q2) and third quartiles (Q3). Similar analysis was performed for the position of permanent teeth and the resorption of primary teeth. To determine the variations between the sex, Mann-Whitney U-test was conducted by comparing the median (Q2) stages.

Results

Variations in dental formation and eruption of permanent teeth and resorption of primary teeth were observed between maxillary and mandibular dentitions and between the sex, however the difference was not statistically significant (p = 0.535 to p = 1.000). The dental atlas was presented separately for Chinese females and males.

Conclusion

This atlas on modern Chinese population serves as a practical tool to assist in clinical diagnosis and treatment planning, in forensic investigations as well as indicators of developments in public health.

Prevalence and patterns of traumatic dental injuries in primary teeth: a 3-year retrospective overview study in Vienna

OBJECTIVES

The aim of this study was to retrospectively identify the prevalence, patterns, and accident types of traumatic dental injuries (TDIs) in children with primary teeth in Vienna, Austria.

MATERIAL AND METHODS

The investigation was conducted as a retrospective overview study including all children with TDIs in primary teeth at the University Dental Clinic of Vienna (Austria) between 2014 and 2016. Dental records including age, gender, location of trauma, type of trauma, cause of TDI, and location of traumatic incident were obtained. Furthermore, the time of presentation and the time span between TDI and initial treatment were evaluated.

RESULTS

The sample comprised TDIs in 243 patients with 403 primary teeth. In a ratio of 1:1.45, boys were significantly more involved than girls. Upper central and lateral incisors were most frequently affected (n = 371, 92.1%). Dislocations were the most common type of injury (n = 298, 74%) with subluxations being the most prevalent form (n = 85, 28.5%). In 23% (n = 92), fractures were observed. The majority of traumatic incidents occurred at home (88.5%).

CONCLUSION

The injury characteristics are comparable to what has previously been reported in other studies in pediatric populations.

CLINICAL RELEVANCE

TDIs are a prevalent event in children worldwide and incisors are the most affected teeth in the primary dentition. Thus, dental practitioners should be able to handle these injuries.

Application of Willems Method as an Age Estimator in Early Adolescents of Bangalore Population

INTRODUCTION

Dental age (DA) assessment is a reliable method for chronological age (CA) estimation used for criminal, forensic, and anthropologic purposes. Age estimation also provides valuable information when the birth date is unavailable, as in case of migrants. Furthermore, the CA of living people is important for employment and marriage purpose.

OBJECTIVES

The aim of the present study is to check the reliability of the Willems method in the population of Bangalore.

MATERIALS AND METHODS

The study was conducted on 205 (109 boys and 96 girls) participants by their radiographic records in the department of forensic odontology using modified Demirjian's method by Willem et al.

RESULTS

A total of 205 subjects were selected for the study, among which 109 (53.2%) were boys and 96 (46.8%) were girls. The mean CA was 12.23 ± 1.75 and the mean DA was 12.20 ± 1.99. Willems method seems to be reliable in estimating DA in Bangalore populations.

CONCLUSION

This study showed that the Willems method gave near precise estimation of the CA.

Dental Pulp-Derived Mesenchymal Stem Cells for Modeling Genetic Disorders

A subpopulation of mesenchymal stem cells, developmentally derived from multipotent neural crest cells that form multiple facial tissues, resides within the dental pulp of human teeth. These stem cells show high proliferative capacity in vitro and are multipotent, including adipogenic, myogenic, osteogenic, chondrogenic, and neurogenic potential. Teeth containing viable cells are harvested via minimally invasive procedures, based on various clinical diagnoses, but then usually discarded as medical waste, indicating the relatively low ethical considerations to reuse these cells for medical applications. Previous studies have demonstrated that stem cells derived from healthy subjects are an excellent source for cell-based medicine, tissue regeneration, and bioengineering. Furthermore, stem cells donated by patients affected by genetic disorders can serve as in vitro models of disease-specific genetic variants, indicating additional applications of these stem cells with high plasticity. This review discusses the benefits, limitations, and perspectives of patient-derived dental pulp stem cells as alternatives that may complement other excellent, yet incomplete stem cell models, such as induced pluripotent stem cells, together with our recent data.

Bisphosphonate Therapy and Tooth Development in Children and Adolescents with Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a heterogeneous connective tissue disorder characterized by repeated fractures and skeletal disorders. At present, bisphosphonate (BP) therapy is the gold standard for OI treatment. The present retrospective study evaluated the effect of BP therapy on tooth development and eruption of permanent teeth in a cohort of children receiving pamidronate. Three groups were studied: patients with OI who were treated with BPs (n = 45), patients with OI who were not treated with BPs (n = 117), and age- and gender-matched healthy controls (n = 121). Dental age, dental maturity, and tooth eruption were assessed on panoramic radiographs using the methods of Demirjian et al. (Hum Biol 45(2):211-227, 1973) and Haavikko (Suom Hammaslaak Toim 66(3):103-170, 1970) and were evaluated using the t-test, Chi-square test, and the Mann-Whitney U test. Dental age in the study group was significantly (p < 0.05) lower than chronological age compared with both control groups. Dental maturity and the eruption of permanent teeth were also significantly (p < 0.05) delayed in the study group in relation to the two control groups. The dental age was significantly lower (p < 0.001) in patients with OI type III treated with BPs compared with healthy controls and the dental maturation was significantly delayed in patients with OI type IV treated with BPs compared with those not treated. In conclusion, BP therapy in OI patients seems to lower the dental age, delay the dental maturity, and tooth eruption. BP administration before 2 years of age might be a contributing factor.

Time and Eruption Sequence of Permanent Teeth in Hyderabad Children: A Descriptive Cross-sectional Study

Context

Eruption of teeth is influenced by various factors. Very few studies were carried out in the past on the eruption time of teeth in the Indian population.

Aim

The aim of the study is to determine the time and sequence, gender differences, pattern of symmetry in the eruption of permanent teeth in Hyderabad children.

Materials and methods

In this cross-sectional study, 1654 schoolchildren (806 girls and 848 boys) in the age group of 5 to 15 years from Hyderabad were examined for the status of eruption of permanent teeth.

Statistical analysis used

Results were subjected to probit’s regression analysis. The average age at eruption of permanent teeth, excluding third molars, was given as the mean [± standard deviation (SD)] in months for each gender. A table of percentiles of the eruption time was also determined.

Results

Unlike most of the earlier studies which showed that girls are ahead of boys in permanent teeth emergence, no such pattern was observed. No significant difference was found in the eruption of permanent teeth in right and left arches. Eruption of all the mandibular teeth, with the exception of right first premolar (44) in both the genders, was earlier than their maxillary counterparts. There was overall delay in the eruption of permanent teeth and significant delay in the eruption of lower canines in both genders.

Conclusion

The significant delay in the eruption of permanent mandibular canines is relevant for orthodontic treatment planning.

How to cite this article: Chaitanya P, Reddy JS, Suhasini K, Chandrika IH, Praveen D. Time and Eruption Sequence of Permanent Teeth in Hyderabad Children: A Descriptive Cross-sectional Study. Int J Clin Pediatr Dent 2018;11(4):330-337.

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.

Early development and replacement of the stickleback dentition

Teeth have long served as a model system to study basic questions about vertebrate organogenesis, morphogenesis, and evolution. In nonmammalian vertebrates, teeth typically regenerate throughout adult life. Fish have evolved a tremendous diversity in dental patterning in both their oral and pharyngeal dentitions, offering numerous opportunities to study how morphology develops, regenerates, and evolves in different lineages. Threespine stickleback fish (Gasterosteus aculeatus) have emerged as a new system to study how morphology evolves, and provide a particularly powerful system to study the development and evolution of dental morphology. Here, we describe the oral and pharyngeal dentitions of stickleback fish, providing additional morphological, histological, and molecular evidence for homology of oral and pharyngeal teeth. Focusing on the ventral pharyngeal dentition in a dense developmental time course of lab-reared fish, we describe the temporal and spatial consensus sequence of early tooth formation. Early in development, this sequence is highly stereotypical and consists of seventeen primary teeth forming the early tooth field, followed by the first tooth replacement event. Comparing this detailed morphological and ontogenetic sequence to that described in other fish reveals that major changes to how dental morphology arises and regenerates have evolved across different fish lineages. J. Morphol. 277:1072-1083, 2016. © 2016 Wiley Periodicals, Inc.

Secular trend in the maturation of permanent teeth in a sample of Turkish children over the past 30 years

This study was performed to evaluate the influence of secular trends on dental maturation among Turkish children over the past 30 years. Orthopantomograms of 757 (385 boys, 372 girls) Turkish children born in the 1980s, 1990s, and 2000s were evaluated. Three groups were formed based on decade with five subgroups by age from 9 to 13 years old for each gender. The number of samples in each age group and gender were matched. The mandibular left seven permanent teeth were evaluated based on formation stage to determine the overall dental maturity score. The groups were compared based on decade and gender. The Bonferroni-corrected Mann-Whitney U test and Kruskal-Wallis tests were used for statistical evaluation. Among 11-, 12-, and 13-year-olds born in the 2000s, girls exhibited significantly more mature dentition than did boys (p<0.01, p<0.05, and p<0.05, respectively). Twelve-year-old girls born in the 1990s and 2000s exhibited significantly more mature dentition than did girls born in the 1980s (p<0.01). Girls generally exhibited more mature dentition than boys. No significant positive secular trends in dental maturity were observed from the 1980s through the 2000s. Dental maturation among Turkish children was not affected by a secular trend.

[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.

Odontostomatologic involvement in juvenile localised scleroderma of the face

AIM

Localised scleroderma of the face (LSF) can lead to significant aesthetical and functional abnormalities. Despite their quite frequent clinical observation, the odontostomatologic complications are not thoroughly described. Aim of the study was to describe the clinical features of the most frequent odontostomatologic abnormalities of LSF and to propose clinical and radiologic criteria for the assessment and follow-up of these complications.

METHODS

  We performed a cross-sectional, multicenter study involving a multidisciplinary team formed by paediatric rheumatologists, orthodontists and radiologists. Patients with a diagnosis of LSF underwent a comprehensive rheumatologic evaluation, dental examination, conventional radiology (orthopantomography, teleradiography) and cone beam computed tomography.

RESULTS

16 patients, nine F, seven M, aged 6.5-21.9 years, were investigated. The mean disease duration was 7.7 years, 62.5% had extracutaneous complications. All patients reported at least one odontostomatologic complication. The main alterations were: malocclusion (94%), overgrowth tendency of the anterior lower third of the face (82%), gnatologic alterations (69%), dental anomalies (63%), skeletal asymmetry (56%), bone involvement (50%) and temporomandibular joint involvement (19%).

CONCLUSIONS

We found a high incidence of odontostomatologic abnormalities in LSF. Cone beam computed tomography represents a new feasible technique to evaluate and monitor soft and hard tissue changes in LSF. The observed findings highlight the importance of a multidisciplinary and standardised management of this challenging and rare condition.

Estimating the distribution of probable age-at-death from dental remains of immature human fossils

In two historic longitudinal growth studies, Moorrees et al. (Am J Phys Anthropol 21 (1963) 99-108; J Dent Res 42 (1963) 1490-1502) presented the "mean attainment age" for stages of tooth development for 10 permanent tooth types and three deciduous tooth types. These findings were presented graphically to assess the rate of tooth formation in living children and to age immature skeletal remains. Despite being widely cited, these graphical data are difficult to implement because there are no accompanying numerical values for the parameters underlying the growth data. This analysis generates numerical parameters from the data reported by Moorrees et al. by digitizing 358 points from these tooth formation graphs using DataThief III, version 1.5. Following the original methods, the digitized points for each age transition were conception-corrected and converted to the logarithmic scale to determine a median attainment age for each dental formation stage. These values are subsequently used to estimate age-at-death distributions for immature individuals using a single tooth or multiple teeth, including estimates for 41 immature early modern humans and 25 immature Neandertals. Within-tooth variance is calculated for each age estimate based on a single tooth, and a between-tooth component of variance is calculated for age estimates based on two or more teeth to account for the increase in precision that comes from using additional teeth. Finally, we calculate the relative probability of observing a particular dental formation sequence given known-age reference information and demonstrate its value in estimating age for immature fossil specimens.

Emergence of the first permanent molar in 5-6-year-old children: implications from a longitudinal analysis for occlusal caries prevention

The timing of tooth emergence is of considerable importance in the planning of prevention of occlusal caries.

OBJECTIVE

The aim was to estimate the trends of emergence of the first permanent molars in girls and boys between 5-6 years of age, since more children are included in the first grade after Brazilian elementary education has been extended from eight to nine years of duration.

METHODS

Dental spaces of 497 children aged 60 months or older were examined four times by a calibrated dentist (kappa > 0.97) during 18 months in a longitudinal study. The first permanent molar was considered emerged when any tooth surface could be reached by a ball point probe. Participants' age was measured in months; 95% confidence intervals were obtained for prevalence and incidence values for each sex in three age groups--60.0 to 65.9; 66.0 to 71.9; 72.0 to 77.9 months. Incidence rate ratios were estimated by Poisson regression analysis.

RESULTS

The majority of children from 66.0 to 71.9 months and 72.0 to 77.9 months presented at least one emerged permanent molar. For each three children in the 66.0-71.9-month group, at least one had all four permanent molars emerged.

CONCLUSION

The emergence trends observed justify the need for specific protection and surveillance measures for occlusal caries prevention.

Dental caries prevalence and treatment needs of 5- to 12-year-old children in relation to area-based income and immigrant background in Greece

OBJECTIVES

  To investigate the association between certain socio-demographic characteristics and dental health status of 5- to 12-year-old children attending public kindergarten and primary schools in Piraeus, Greece.

METHODS

  Gender, age, place of residence, immigrant background and area-based income were associated with dental caries prevalence, treatment needs and oral hygiene level in 5,116 children.

RESULTS

  The mean number of decayed, missing and filled deciduous teeth (dmft) and Unmet Restorative Treatment Needs Index (UTN) at 6-year-olds were 1.54 and 84.6% respectively, and the DMFT and UTN at 12-year-olds were 1.35 and 71.8%. Caries experience/severity significantly increased with age, whereas treatment needs and oral hygiene level decreased (P<0.001). Immigrant background and low area-based income was associated with poorer oral health outcomes. The above associations retained statistical significance after multivariate analysis. Children who live in areas with lower average income present 1.20 to 2.14 greater risk of having higher caries severity and poorer oral hygiene in comparison to those living in more affluent areas, and children with an immigrant background have 1.68 to 4.34 higher likelihood to present higher dmft and DMFT values, higher unmet treatment needs, and poorer oral hygiene levels compared to their Greek counterparts above and beyond the effect of the other risk factors assessed.

CONCLUSIONS

  The present study revealed a socio-demographic gradient in oral health status and treatment needs of children in Piraeus, Greece.

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.

Diagnosing dental caries in populations with different levels of dental fluorosis

The aim of this study was to assess the reliability of the Nyvad visual-tactile caries-diagnostic criteria when used among children who have been lifelong residents in areas with 'optimal' or low concentrations of fluoride in the drinking water. In each of two areas with drinking water fluoride concentrations of 0.3 and 1.1 ppm (0.3 and 1.1 mg/l) fluoride, respectively, 150 children were clinically examined twice, 2 wk apart, for dental fluorosis, using the Thylstrup-Fejerskov index (TF index), and for dental caries using the Nyvad visual-tactile caries criteria. The prevalence of dental fluorosis was 45% in the 1.1 ppm fluoride area and 21% in the 0.3 ppm fluoride area. When the results of the duplicate caries recordings were compared at the surface level, only minute differences were observed in the percentage agreement (91.7 and 90.7%, respectively) and in the kappa values (0.73 and 0.72, respectively). When individual DFS counts were compared across examinations using Bland-Altman plots and estimation of prediction intervals for the differences, we observed a greater variability of the differences between recordings among children from the low-fluoride area. Contrary to our expectations, a pronounced dental fluorosis background did not reduce the reliability of the caries recordings, which appeared to be slightly less reliable at very low levels of dental fluorosis.

[Correlation of dental age and anthropometric parametres of the overall growth and development in children]

INTRODUCTION/AIM

Anthropometric methods of measuring the whole body and body parts are the most commonly applied methods of analysing the growth and development of children. Anthropometric measures are interconnected, so that with growth and development the change of one of the parameters causes the change of the other. The aim of the paper was to analyse whether dental development follows the overall growth and development and what the ratio of this interdependence is.

METHODS

The research involved a sample of 134 participants, aged between 6 and 8 years. Dental age was determined as the average of the sum of existing permanent teeth from the participants aged 6, 7 and 8. With the aim of analysing physical growth and development, commonly accepted anthropometric indexes were applied: height, weight, circumference of the head, the chest cavity at its widest point, the upper arm, the abdomen, the thigh and thickness of the epidermis. The dimensions were measured according to the methodology of the International Biological Programme. The influence of the pertinent variables' related size on the analysed variable was deter mined by the statistical method of multivariable regression.

RESULTS

The middle values of all the anthropometric parametres, except for the thickness of the epidermis, were slightly bigger with male participants, and the circumference of the chest cavity was statistically considerably bigger (p < 0.05). The results of anthropometric measurement showed in general a distinct homogeneity not only of the sample group but also within gender, in relation to all the dimensions, excyt for the thickness of the epidermis. The average of the dental age of the participants was 10.36, (10.42 and 10.31 for females and males respectively). Considerable correlation (R = 0.59) with high statistical significance (p < 0.001) was determined between dental age and the set of anthropometric parameters of general growth and development.

CONCLUSION

There is a considerable positive correlation (R = 0.59) between dental age and anthropometric parameters of general growth and development, which confirms that dental development follows the overall growth and development of children, aged between 6 and 8 years.

Prevalence and distribution of demarcated opacities in permanent 1st molars and incisors in 6 to 8-year-old Danish children

OBJECTIVE

To estimate the prevalence and describe the distribution of demarcated opacities and possible consequences of this condition in permanent 1st molars and incisors in Danish children.

MATERIAL AND METHODS

Among all 6 to 8-year-old children in two municipalities, 745 (83.6%) were clinically examined for the occurrence of creamy-white or yellowish-brown demarcated opacities, posteruptive breakdown of tooth substance in relation to the opacities, atypical restorations, and extractions, i.e. restorations or extractions as a result of the occurrence of demarcated opacities.

RESULTS

In 647 children with four fully erupted permanent 1st molars, the prevalence of demarcated opacities and of lesions with loss of tooth substance due to demarcated opacities in any 1st molar was 37.3% (95% confidence interval (95% CI) 33.6-41.0%) and 6.3% (95% CI 4.7-8.5%), respectively. Permanent incisors were 2.5 times more frequently affected among children with one or more affected permanent 1st molar than among children with no such teeth. Demarcated creamy-white opacities were the type of lesion found most frequently, and the most frequently affected tooth types were the upper central incisors followed by 1st molars.

CONCLUSIONS

Nearly half of the examined 6 to 8-year-old children had permanent 1st molars or incisors with demarcated opacities. More than 6% of the children had macroscopic loss of tooth substance due to demarcated opacities.

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.

Effect of caries experience in primary molars on cavity formation in the adjacent permanent first molar

This study sought to address the influence of a sound versus affected first and/or second deciduous molar on the incidence of visible caries experience in the adjacent permanent first molar. Clinical and questionnaire data were obtained from a 6-year prospective oral health screening project in Flanders, Belgium (Signal-Tandmobiel project), where 4,468 children (born in 1989) were examined annually during their primary school time. A multiple survival model allowing for dependent data with possible censoring was applied. The impact of timing of tooth emergence (determining the period at risk), gender, presence of sealants and reported oral hygiene habits was also considered. Cavity formation in permanent first molars was clearly influenced by the status of the adjacent primary molars;the effect of the second deciduous molar was most pronounced. Moreover, if both deciduous molars experienced caries and the child presented with poor oral hygiene, a peak in cavity formation of the permanent first molar 1-2 years after emergence was noticed. On the other hand, if a child presented with good oral hygiene, no peak was observed; caries risk increased slightly over time. No significant benefit from restoring primary molars could be demonstrated, possibly because of methodological limitations.

Multivariate survival analysis for the identification of factors associated with cavity formation in permanent first molars

This investigation used a multivariate survival model, which allowed for dependent caries data with possible censoring, to analyse the impact of timing of tooth emergence, gender and several reported oral hygiene and dietary habits on the incidence of cavity formation in permanent first molars (PFM) in young children. A 6-yr prospective oral health screening project in Flanders, Belgium, provided clinical and questionnaire data on 4,468 children. The results revealed that PFM in children who reported frequent brushing, who had no visible caries experience in the primary dentition, and who presented without occlusal plaque on the PFM had the best survival estimates. Girls had a higher incidence than boys of cavity formation in mandibular molars. The multiple survival analysis confirmed the major impact of the caries status of the deciduous dentition and self-reported oral hygiene habits on the incidence of cavities in permanent first molars.

Longitudinal analysis of deciduous tooth emergence: IV. Covariate effects in Japanese children

Emergence of the deciduous teeth is generally considered to be robust to moderate environmental insults, malnutrition, and disease. Consequently, deciduous tooth emergence has been used to assess growth and development and for age estimation in children. In this paper, we examine the way in which nutritional status and other covariates affect deciduous tooth emergence in a sample of 114 Japanese children born in Tokyo in 1914 and 1924. Parametric survival analysis was used to quantify the effects of nutritional status, breastfeeding behavior, and sex on the hazard of deciduous tooth emergence. Children of poor nutritional status exhibited significantly delayed emergence of all deciduous teeth, with effects that ranged from 14-29% increases in mean emergence times. Children of medium nutritional status exhibited increases in mean emergence times of 5-9% for the canines and lower molars, and 13-17% for the incisors. Partial breastfeeding had no effect on tooth emergence, but children who were not breastfed at all showed delayed emergence of the upper incisors. No significant sex differences in emergence were found. The findings contradict the idea that moderate malnutrition has little effect on deciduous tooth emergence. Furthermore, nutritional differences may account for some of the observed differences among populations in the timing of tooth emergence.

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.

Impact of caries experience in the deciduous molars on the emergence of the successors

The purpose of this study was to evaluate the effect of caries experience in a primary molar (decayed and/or restored vs. extracted) on the timing of emergence of its successor. Data were obtained from a longitudinal epidemiological study in a sample of 4468 Flemish children. Survival analyses with log-logistic distribution were performed to calculate median emergence ages and 95% confidence intervals (CI); caries experience was added as a covariate. The results indicate that the emergence of the maxillary and mandibular premolars was accelerated by 2-8 months when its predecessor had been decayed and or restored but had not been extracted. Premature loss of maxillary primary molars resulted in a significant acceleration of the emergence of the premolars; this was not observed in the mandible. In conclusion, when considering permanent tooth emergence ages, caries experience in the primary dentition should be taken into account.

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.

Modelling tooth emergence data based on multivariate interval-censored data

Studies on emergence of (permanent) teeth are published regularly in the dental literature. Besides descriptive statistics (mean or median values) on emergence times, comparisons between boys and girls are of interest. Gender comparisons are intersubject analyses, but also intrasubject questions, like 'Is there a left-right symmetry with respect to the mean (median) emergence times?' are of interest. Studies on emergence times most often are faced with interval-censored data. We will extend a GEE-type test proposed by Huster et al. for bivariate right-censored data to the multivariate setting with interval-censored data. Central to our paper is to provide appropriate statistical models to resolve some dental questions on emergence. The analyses are based on data from the longitudinal Signal-Tandmobiel study.

Biological interpretation of the correlation of emergence times of permanent teeth

The eruption mechanism is not fully understood. It is known that the dental follicle is essential and that experimentally provoked denervation influence the process of eruption. Accordingly, the purpose of this study was to elucidate the eruption pattern in a human population and relate this pattern to the pattern of jaw innervation. The eruption pattern was evaluated from the correlation between the emergence times of different teeth in the permanent dentition based on longitudinal data from a large national registry (12,642 boys and 12,095 girls). Correlations coefficients were generally high (>0.5) and higher between teeth within the same tooth groups (i.e. incisors, canines and premolars, and molars) than between teeth from different tooth groups. It was shown that the correlation in emergence of teeth closely followed the pattern of innervation of the jaws. Thus the study supported the hypothesis concerning a possible association between eruption and innervation.