Journal of Oral Research and Review

: 2022  |  Volume : 14  |  Issue : 1  |  Page : 28--37

Eruption chronology of 1st permanent tooth and evaluation of several factors among the children of Kolkata − An original research

Trisha Das Sarma, Gautam Kumar Kundu, Taniya Thakur, Poulam Guha 
 Department of Pediatric and Preventive Dentistry, Gurunanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India

Correspondence Address:
Trisha Das Sarma
157/F Nilgunj Road, Panihati, Sodepur, Kolkata - 700 114, West Bengal


Objective: Eruption is an orderly, sequential, age-specific event and an important milestone during child's development. Along with the study of prenatal and postnatal growth, diagnosis and treatment planning and maintaining birth records also need idea about proper eruption sequence. The purposes of this study are as follows: To determine which permanent tooth first erupts and at which age, identify if any difference exists with the existing eruption sequence and to note factors if any related to specific eruption chronology among the 5–7 years' old children of North Kolkata. Materials and Methods: Socioeconomic statuses were noted as per the Modified Kuppuswamy Scale. Body mass index (BMI) was calculated with Centers for Disease Control and Prevention child and teen BMI calculator. Tooth notation was recorded using the foreign direct investment system. Children in whom no permanent tooth was erupted, intraoral periapical radiograph was taken with the help of dental mesh gauge in mandibular (mand.) anterior and posterior region. Variables which may influence eruption time were recorded in prevalidated questionnaire. Statistical analysis was performed using IBM SPSS 20.0 software. Results: Mand. central incisor (CI) was the 1st erupted permanent tooth in 31.8% children and Mand. 1st Molar (M1) in 67.9% of total study population. The mean age of eruption of 1st erupted permanent tooth was 5.981 ± 0.547 years. More no of samples (3.80%) from upper socioeconomic status have shown Mand. CI as 1st erupted permanent tooth. Percentage of preterm children (20%) and infants with any systemic diseases (9.50%) were also more in this group. Conclusion: In many children, Mand. CI is the 1st erupted permanent tooth; this is definitely a Milestone Data and did not match with Kronfild and Schour's permanent teeth eruption time table which we are blindly following for years. Parental education and further periodic revaluation are needed for future purpose.

How to cite this article:
Sarma TD, Kundu GK, Thakur T, Guha P. Eruption chronology of 1st permanent tooth and evaluation of several factors among the children of Kolkata − An original research.J Oral Res Rev 2022;14:28-37

How to cite this URL:
Sarma TD, Kundu GK, Thakur T, Guha P. Eruption chronology of 1st permanent tooth and evaluation of several factors among the children of Kolkata − An original research. J Oral Res Rev [serial online] 2022 [cited 2022 Jun 27 ];14:28-37
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During eruption process, tooth moves axially from its nonfunctional position in the osseous crypt to functional occlusion with its antagonist. The appearance of any part of the cusp or crown through gingiva may be used as a clinical marker for eruption.[1]

As per the present literature, 1st mand. molar is the 1st permanent tooth to erupt in the oral cavity, which appears between 6 and 7 years. As size of the first permanent molar tooth determines the shape of the mouth, they are known as “Keystones of Dental Arch.”[2] However, various recent studies and clinical observations have revealed some changes in the existing eruption pattern in the permanent dentition.

According to Adolph “Schultz's rule” (1983), Homosapiens, the slowest growing mammals, replace deciduous teeth before completing molar eruption. Eruption of permanent teeth and replacement of deciduous tooth occurs simultaneously in them. In humans, particularly “white” populations, permanent lower central incisor (CI) erupts earlier than Ml.[3]

Following are the importance of this study:

The formation and development of dentition and growth of craniofacial complex are closely related. As first permanent tooth stimulates the rate of postnatal growth of the jaw, eruption schedule helps in the study of growthEstimation of dental age is an important tool in orthodontic treatment planning, preventive dentistry procedures, archeological, anthropological, and paleontological applicationDelayed tooth eruption may cause malocclusion and crowding, poor oral health, parental concerns, and nutritional problems. Teeth with early eruption have higher risks for dental caries. Sequencing of eruption may affect periodontal and temporomand. joint disorders[1]Table of Krenfild and Logan was further modified by Kronfild and Schour (1939) is accepted as standard for many years.[4],[5] Racially, genetically and environmentally Indians are different from westerners. Hence, studies done in other countries cannot provide relevant guidance on the eruption schedule in the Indian populationIn a developing country like India, a large number of people have no records of their date of birth which is required by forensic practitioners and law enforcing agencies, different age limited competitions, consent, criminal abortion, employment, at the time of schooling, during retirement, and attainment of majority.

The aim of our study is to determine which permanent tooth first erupt in the oral cavity and at which age, identify if any difference exists in the eruption sequence of 1st permanent teeth in this population with the existing eruption schedules and factors if any related to specific eruption chronology among the 5–7 years' old children of North Kolkata.

 Materials And Methods

After getting approval by the ethics committee, a prevalidated questionnaire was developed. The first part emphasized on the demographic characteristics, tooth notation of the child, socioeconomic status of the parent (Modified Kuppuswamy Scale January 2017), and the 2nd part contained 6 closed-ended and 4 open-ended questions about the variables influencing the time of eruption.

Sample size n = (DEFF × Np [1-p])/([d2/Z21-α/2 × [N-1] + p × [1-p]) a sample size of 660 at 99% confidence interval was obtained.

Permission was taken from the school authorities, procedures, and motto of the research was fully explained, and informed consent (understandable language) was obtained from the parents/guardians of the children before the investigation. Children were selected from the OPD of department of pediatric and preventive dentistry and from some primary schools of North Kolkata.

5–7 years old children, born and brought up in the study area irrespective of any caste and religion, accompanied with their parents and whose parents could tell us about the 1st erupted permanent tooth, their exact eruption time and shedding time of the corresponding deciduous tooth, were included in our study.

However, whose parents could not inform properly about the 1st erupted tooth where both the permanent mand. CI and the permanent mand. 1st molar was in the occlusal level and could not notify about the exact eruption time of the 1st permanent tooth, migratory children, children with any known genetic, congenital disorder and with cleft lip and cleft palate were excluded.

Demographic data was recorded from randomly selected 1000 children. Out of which 661 were selected as the study population after considering inclusion and exclusion criteria.

Instruments which were used for intraoral examination were sterilized by Autoclave at 132 degree Celsius for 10 min under 30 psi. Cold sterilization of X-ray mesh gauge was done by soaking into Korsolex Rapid (glutaraldhyde solution) for 15–20 min every time before use.

A single trained investigator collected information, filled the previously designed questionnaire, and performed an oral assessment and examination for all children to minimize inter-observer variation.

Date of birth was recorded from the school register and the birth certificate of school children and outdoor patients, respectively. The age was calculated from each child's date of birth recorded in the school register to the date of examination and rounded off to the full month.

Students were weighed in kilograms using a weighing machine and height was measured using a wall-mounted height chart with their back and knees completely straight and their feet together. The height was then rounded to the nearest feet and inches. Body mass index (BMI) was calculated from recorded height and weight with the help of Centers for Disease Control and Prevention child and teen BMI calculator widget.

Dental examination was carried out with the subject seated on an ordinary chair, under natural light using a mouth mirror and pictures were taken with the help of intraoral mirror. Status of eruption of each permanent tooth was recorded using mouth mirror to retract soft tissues. If any part of a tooth was visible, the tooth was regarded as erupted and recorded on the survey sheet accordingly [Figure 1] and [Figure 2].{Figure 1}{Figure 2}

Children in whom no permanent tooth was erupted, intraoral periapical radiograph is taken with the help of dental mesh gauge in mand. anterior and posterior region to calculate the overlying bone length and to check root development [Figure 3] and [Figure 4].{Figure 3}{Figure 4}

In the final step following points were noted in the proforma: The child was born by caesarean section or normal delivery; birth was preterm, term or postterm; any known systemic disease of the child or the mother during pregnancy and delivery, any disturbance in deciduous or permanent tooth eruption and shedding in parents or siblings, child prefers rough course, semi liquid or liquid food; commonly swallows or chew food; delayed, early or normal eruption time; natural shedding or extraction of the corresponding deciduous tooth if any; 1st permanent tooth erupted in oral cavity and the exact time of eruption.

Descriptive and inferential statistical analyses were done using statistical software IBM SPSS statistics 20.0 (IBM Corp., Armonk, N.Y., USA). Continuous measurements were presented on mean ± standard definition Chi-square analysis was used to find the significance of study parameters on the categorical scale, and Student's t-tests (two tailed, unpaired) were used to find the significance of the study parameters on continuous scale between two groups. Level of significance was fixed at P = 0.05, any value ≤0.05 was considered to be statistically significant and P < 0.001 as highly significant.


Mand. CI was the 1st erupted permanent tooth in 31.8%, Mand. 1st molar was the 1st erupted permanent tooth in 67.9% and maxillary 1st molar was the 1st erupted permanent tooth in 0.9% of the total study population [Diagram 1]GROUP A→ children having Mand. 1st Molar as 1st erupted permanent toothGROUP B→ children having Mand. CI as 1st erupted permanent toothMean age of eruption of 1st permanent tooth was 5.981 ± 0.547 years. Mean time of eruption of children of GROUP A was 5.9883 ± 0.52413 years and that of children of GROUP B was 5.9826 ± 0.59240 years [Diagram 2].This difference is not statistically significant [Table 1] and [Table 2]Mean age of shedding of corresponding deciduous teeth was 5.8881 ± 0.8082 years [Diagram 3]GROUP A constitutes 78% male and 22% female, and in GROUP B, there was 80% male and 20% female. No gender wise discrimination was noted between the two groups. However, the result is not statistically significant [Diagram 4] and [Table 3]In GROUP A children, mean BMI was 16.801 ± 2.9347 and in GROUP B children, mean BMI was 16.450 ± 2.9312. Mean BMI wise no statistically significant difference exists between the groups [Table 2]However, among GROUP A children, 52.6% were healthy, 20.9% were obese, 17.5% were overweight and 9% were underweight and in GROUP B; 45.7% were healthy, 19% were obese, 17.1% were overweight, and 18.1% were underweight. More percentage of underweight children was there in the Group B. The calculated difference is statistically significant as P = 0.009 [Diagram 5], [Diagram 6] and [Table 4]In GROUP A, 46.7% children were from lower middle (LM) class family, 0.4% were from upper (U) class, 38.7% were from upper lower (UL) class, and 14.2% were from upper middle (UM) class family. In GROUP B, 46.7% were from LM class family, 3.8% were from upper class, 36.2% were from UL class, and 13.3% were from UM class family. The calculated difference is statistically significant as P = 0.013 [Diagram 7] and [Table 5]59.1% children were born through cesarean © section, 1.8% through forceps delivery and 39.1% through normal (N) delivery in GROUP A. 66.7% were born through cesarean section, 1.0% through forceps delivery and 32.4% through normal delivery in GROUP B. This difference is not statistically significant [Diagram 8] and [Table 6]1.3% post term delivery, 13.3% pre term delivery and 85.4% term delivery were recorded in GROUP A. 3.8% postterm delivery, 20.0% preterm delivery, and 76.2% term delivery was recorded in GROUP B. The calculated difference is statistically significant as P = 0.008 [Diagram 9] and [Table 7]Mothers of 5.4% children of Group A and mothers of 4.8% children of Group B possessed some systemic diseases. No statistically significant difference exists [Diagram 10] and [Table 8]In GROUP A 3.1% and in GROUP B 9.5% had some systemic diseases present. The calculated difference is highly statistically significant as P < 0.001 [Diagram 11] and [Table 9]Siblings of 0.4% children of GROUP A showed delayed eruption of permanent or deciduous tooth. Result is not statistically significantAmong Group A children, 0.4% was habituated to consume liquid food items, 89.7% was habituated to consume rough coarse food items and 9.9% was habituated to consume semi liquid food items. Among Group B population, 1.9% was habituated to consume liquid food items, 89.5% was habituated to consume rough coarse food items and 8.6% was habituated to consume semi liquid food items. The difference is not statistically significant [Diagram 12] and [Table 10]91.9% children consume food items by chewing and 8.1% by swallowing in Group A. 89.5% consume food items by chewing and 10.5% by swallowing in Group B. The difference is not statistically significant [Diagram 13] and [Table 11]In GROUP B, parents of 21.9% had given a history of extraction of corresponding deciduous tooth, 74.3% had given history of natural shedding and in 3.8% no permanent tooth was eruptedIn GROUP A, primate space or generalized spacing was available in the oral cavities of only 19.1% and not available in 80.9%. Whereas in GROUP B, primate space or generalized spacing was available in 81.9% and was not present in 18.1%. Calculated values are highly statistically significant as P < 0.001 [Diagram 14], [Diagram 15] and [Table 12].[INLINE:1][INLINE:2]{Table 1}{Table 2}[INLINE:3][INLINE:4]{Table 3}[INLINE:5][INLINE:6]{Table 4}[INLINE:7]{Table 5}[INLINE:8]{Table 6}[INLINE:9]{Table 7}[INLINE:10]{Table 8}[INLINE:11]{Table 9}[INLINE:12]{Table 10}[INLINE:13]{Table 11}[INLINE:14][INLINE:15]{Table 12}


North Kolkata is the older area of Kolkata. Along with Tropical climate with a hot and humid weather, religious syncretism and different food habits affect the lifestyle of people staying here. These factors differentiate it from the western countries and other regions of India. All of that can be responsible for the changes in Eruption sequence.

According to Dahlberg and Menagaz-Bock, the cross-sectional method is preferable to the longitudinal method because it includes larger samples, thereby risk of bias is smaller.

Mand. CI was the 1st erupted permanent tooth in 31.8% of study population, which is a clinically significant finding and a MILESTONE DATA. Our result is in accordance with the studies performed by Gupta et al.[6] (2007), Limbu[7] and Chaitanya;[8] but in contrast to the observations done by Carlos and Gittelsohn,[9] Hassanali and Odhiambo,[10] Kochhar and Richardson[11] and Moslemi.[12]

We have not seen any statistically significant differences of mean age of eruption between them. Mean age of eruption was much earlier (5.9 years) than the studies of Kochhar and Richardson[11] among Northern Ireland children and Chaitanya et al.[8] in Hyderabad children (7–7.5) years. However, Gupta et al.[6] described that the teeth of Indian children erupt 5–7 months later than those of black children. In contrast to our study, Lakshmappa et al.[13] observed that mean age of eruption of permanent mand. CI was 1.5–2 years later than that of permanent Mand. 1st molar in the children of Mysore city.

The mean age of shedding of corresponding deciduous tooth was much earlier than the values mentioned in the research papers of Clements et al.[14] and values given by ADA (6–7 years).

Despite the fact that no statistically significant difference between eruption sequence and gender was proved, male predomination was seen in both the groups. Similar result was seen by Lakshmappa et al.[13] and Dashash and Al-Jazar[15] (2018) but contrary findings were seen by Parner et al.[16] and Nizam, et al.[17] where they noted that the mean age of eruption was lower for girls than for boys.

Statistically significant relationship between BMI and sequence of 1st erupted permanent tooth was observed. There were more underweight children in the group of having Mand. CI as 1st erupted permanent tooth. Percentage of overweight children coincides with ICMR-INDIAB study 2015 and observations of Chakraborty et al.[18] in 2011 among children of Kolkata. According to the WHO, malnutrition is the gravest threat and India have 46.6 million (31%) stunted children. The percentage of underweight children was much lower in the study region.

Statistically significant correlation between eruption sequence of 1st erupted permanent tooth and socioeconomic statuses was found. More children from upper class family showed Mand. CI as 1st erupted permanent tooth. In contrary to that, Suresh[19] in 2017 in his study among children of Chennai got no correlation.

The prevalence of cesarean section was much higher in our study area in both of the groups (66% and 59%, respectively) than District Level Household Survey 3[20] where cesarean section rate was found 12%–28.1%. Same result was shown by Alnemer et al.[21]

Percentage of premature children of our study area was in accordance to the present literature. Statistically, more cases of preterm deliveries were reported by children who had Mand. CI as 1st erupted permanent tooth. Alnemer et al.[21] did not observe any significant correlation. Khalifa et al.[22] noted delayed deciduous tooth eruption in preterm babies.

Data of our study showed less percentage of gestational diabetes than Raja et al.[23] less gestational hypertension than Patel et al. in 2017[24] and childhood hypothyroidism in our study area than the study of Singh et al.[25] in 2016 (12.2%). However, children, in whom mand. CI erupted first; more commonly showed any of systemic diseases present in them such as hypothyroidism, asthma, epilepsy, anemia, or thalassemia.

Although not statistically significant, swallowing of food items was more common in the group of children having Mand. CI as 1st erupted permanent tooth.

Primate or generalized spacing were mostly absent in the children showing Mand. CI as first erupted permanent tooth. Highly statistically significant correlation was seen. May be the erupting pressure from the posterior teeth spread to permanent canines and subsequently to the permanent incisors and make them to erupt 1st in nonspaced dentition in mand. arch.

Lack of previous studies was an obstacle for us when we tried to correlate some variables. Further, more number of research on this field, long-term studies with increased sample size, more objective values rather than subjective data and additional inter variable correlations will help to make more appropriate evaluation.


To the best of our knowledge, the present observational descriptive study is the first study conducted to determine the 1st erupted permanent teeth among children of North Kolkata. Percentage of Mand. CI as 1st erupted permanent tooth is pretty high among our study population. We should try to educate parents about proper eruption chronology and sequence so that if any unfamiliar pattern is seen they can contact their dentist which in turn may uncover hidden dental pathology and systemic illness at an early stage. In conclusion, the eruption timing and sequence may alter with time, with changes in social status and patterns of health. Hence, they should be reconfirmed at certain intervals.

Ethical clearance

The study was approved by the institutional ethical committee of Gurunanak Institute of Dental Sciences and Research and certifies that the study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Registration no: GNIDSR/IEC/18–14.

Informed consent

Consent to participate- Informed consent was obtained from the legal guardians of all individual participants included in the studyConsent for publication- the parents have given consent regarding publishing their data.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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