Assessment of mineralization and developmental stage of homologues mandibular first and second molars using panoramic radiographs and Demirjian's method in 5 to 12 years old children

doi:10.21203/rs.3.rs-1716480/v1

Background: Assessment of dental developmental stage is more valuable than tooth eruption because the duration of tooth eruption is short and is determined by the appearance of tooth in the oral cavity. Among the different methods that could be used to determine the developmental stage of teeth, the Demirjian’s method has been extensively applied. This study aimed to assess the developmental stage of homologous mandibular first and second molars in 5 to 12-year olds using the Demirjian’s method.

Methods: This cross-sectional study was conducted on 300 panoramic radiographs of 5 to 12-year-old Iranians obtained from the Radiology Department of Hormozgan University of Medical Sciences from March 2019 to April 2020. The developmental stage of homologous mandibular first and second molars teeth were scored based on Demirjian’s stages. The observers were first calibrated for use of the Demirjian’s method and then the inter- and intra-examiner reliability and the respective kappa values were calculated after observing 300 panoramic radiographs. The radiographs were assessed twice with a one-month interval. The collected data was analysed using SPSS version 22 (SPSS Inc., Chicago, IL).

Results: Significant difference was noted in the developmental stage of the first and second molars in the right and left side among the different age groups. According to the results, there was not a significant difference in the developmental stage of the first molars in right and left side between two genders while the difference in this regard between the mandibular right and left second molars between two genders was significant. Moreover, there was a significant difference in the development of the first and second molars in the right and left side between the four distributed age groups for each gender.

Conclusion: According to the findings of this study, evolution of mandibular first and second molar is not an appropriate indicator for gender segregation in children under 12 years old, but it can be used in ages estimation. Therefore, it can be concluded that gender is an impactful factor on the growth process of the second molar on the left and right in this age group.

Mineralization

Homologous teeth

Demirjian’s Method

Panoramic Radiography

Tooth development is used for age estimation in many disciplines including anthropology, archaeology, paediatric dentistry and orthodontics (1). Dental development is a gradual and progressive process led by the interaction between genetic, epigenetic, and environmental factors over time (2). However, geographical differences in climate and the related physical factors such as temperature, sun exposure and humidity have caused diversity in growth as well as dental development among populations (3-6). Several methods are used to determine the stage of development of teeth (2, 7, 8). Most of these methods are based on radiographic comparison of tooth development with standard curves (7-9). Dental age estimation is more accurate in children because their teeth are still developing while in adults, it is extremely dependent on environmental factors (10). In 1973, Demirjian introduced a method for assessment of dental age based on developmental stage of teeth on panoramic radiographs of a large population of French-Canadian children (8). In this method, development of seven permanent teeth in the mandibular left quadrant is evaluated on panoramic radiographs and is classified into eight stages from A to H (11). This method is accepted worldwide and is the most common method for estimating dental age (8, 12). The advantages of Demirjian method is that it is relatively a simple method which involves the identification of the stage of mineralisation on radiographic images followed by their comparison with the standard stage. Studies on other societies, recorded patterns of comparatively advanced or delayed dental development. Many authors have investigated the validity of the Demirjian’s method and the discussion of its population-specific standards for age estimation (13-17).

Considering all the above, this study aimed to assess the difference in developmental stage of the homologous mandibular first and second molars in 5 to 12-year olds Iranian children. In most studies, Demirjian method is used to compare the dental age and chronological age of patients. Number of studies comparing the mineralization time and developmental stages of homologous teeth are scarce; thus, further studies are required in this respect. Assessments in our study were made on panoramic radiographs. The null hypothesis was that no significant difference exists in the developmental stages of homologous teeth.

Data collection

This cross-sectional study was conducted on 300 panoramic radiographs of 5 to 12-year-old Iranians obtained from Radiology Department of Hormozgan University of Medical Sciences from March 2019 to April 2020 according to ethical guidelines.

Inclusion criteria for the sample was based on group of patients living in Bandar Abbas with chronological age between 5 to 12 years, without any specific dental disorders such as dysplasia or dentin and enamel hypoplasia, missing tooth, history of jaw fractures and lesions. Panoramic radiographs had been requested by a paediatric dentist for orthodontic treatment and were taken with similar exposure settings. Written informed consent was obtained from the parents and the study was approved in the ethics committee of the university.

Panoramic radiographs were taken using Cranex D extra-oral dental X-ray unit (Helsinki, Finland) by an oral and maxillofacial radiologist. All images were saved in DICOM format using Scanora Lite software.

Scoring of the radiographs

All panoramic radiographs were viewed on a monitor and studied using Scanora Lite software. Each panoramic radiograph was coded so that the observers were blinded to the identity, gender or sex of patients.

Two observers used the Demirjian’s method for assessment of tooth development. The two observers were senior dental students instructed on how to use the Demirjian’s method by two oral and maxillofacial radiologists. The developmental stage of teeth was classified from A to H according to the Demirjian’s method (Figure1). Developmental stage of mandibular left and right first and second molars was determined accordingly and recorded in a spreadsheet.

Reproducibility

For the purpose of calibration of observers, twenty percent of the panoramic radiographs (60 OPGs) were randomly chosen using electronically generated random numbers and evaluated in a pilot study. The inter-observer reliability was obtained to be 0.83. The disagreements were resolved by discussion and the coefficient of agreement became 1. All panoramic radiographs were evaluated twice with a one-month interval (to decrease fatigue). The inter- and intra-examiner reliability were then calculated.

Data Analysis

The obtained data was analysed using SPSS version 22 (SPSS Inc., Chicago, IL). Kappa coefficient was calculated to determine the intra- and inter-observer agreement. Wilcoxon signed Rank test was used for comparison between the left and right sides of the mandible. Moreover, Chi Square test was employed to evaluate the correlation between the developmental stages and age groups divided by gender.

300 panoramic radiographs (OPGs) belonging to individuals (160 males and 140 females) aged between 5 and 12 years (mean age = 8.38 years; standard deviation [SD] = 1.99) were analysed.

The distribution of gender and age of the study sample were summarized in table 1.

Table 1. Distribution of the sample by age and biological sex

		Number	Percentage
Sex	Male	160	53.3%
Sex	Female	140	46.7%
Age	5 to 6	64	21.3%
	7 to 8	97	32.3%
	9 to 10	88	20.9%
	11 to 12	51	17.1%

The distribution of first and second molars in terms of frequency and percentages are summarized in table 2.

Table 2. Distribution of first and second molars

Tooth developmental stage	Right side first molar		Left side first molar		Right side second molar		Left side second molar
Tooth developmental stage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage
A	0	0%	0	0%	14	4.7%	11		3.7%
B	0	0%	0	0%	30	10.1%	26		8.8%
C	0	0%	0	0%	63	21.1%	71		23.9%
D	7	2.3%	7	2.3%	96	32.2%	95		32%
E	62	20.7%	63	21%	75	25.2%	74		24.9%
F	57	19%	56	18.7%	15	5%	15		5%
G	100	33.3%	97	32.3%	3	1%	3		1%
H	74	24.7%	77	24.7%	2	0.7%	2		0.7%

Using Wilcoxon signed rank test, out of 300 first molars, 296 (98.6%) were in the same developmental stage; only one first molar (0.3%) in the right side was one stage ahead of those in the left side, and 3 (1%) first molars in the right side were one stage behind of those in the left side. The difference between the first molars in the right and left sides was not significant and they were almost in the same developmental stage (P=0.625) as summarized in Table 3.

Table 3. Frequency and percentage of agreement in the developmental stage of right and left first molars

Tooth developmental stage	D		E		F		G		H		P-value
Tooth developmental stage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	0.625
D	7	2.3%	0	0%	0	0%	0	0%	0	0%
E	0	0%	62	20.7%	0	0%	0	0%	0	0%
F	0	0%	1	0.3%	56	18.7%	0	0%	0	0%
G	0	0%	0	0%	0	0%	97	32.3%	3	1%
H	0	0%	0	0%	0	0%	0	0%	74	24.7%

Based on the results, out of 300 second molars, 281 (93.6%) were in the same developmental stage; 6 second molars (2%) in the right side were one stage ahead of those in the left side, and 10 (3.3%) second molars in the right side were one stage behind of those in the left side. The difference between the first molars in the right and left sides was not significant (P=0.454) Table 4.

Table 4. Frequency and percentage of agreement in the developmental stage of the right and left second molars

Tooth developmental stage	D		E		F		G		H		P-value
Tooth developmental stage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	Frequency	Percentage	0.454
D	7	2.3%	0	0%	0	0%	0	0%	0	0%
E	0	0%	62	20.7%	0	0%	0	0%	0	0%
F	0	0%	1	0.3%	56	18.7%	0	0%	0	0%
G	0	0%	0	0%	0	0%	97	32.3%	3	1%
H	0	0%	0	0%	0	0%	0	0%	74	24.7%

Determining the frequency of developmental stages of the first and second homologous molars based on the age

According to the results of chi-square test, there was a significant difference in developmental stage of right (Chi-Square = 410.146, P <0.001) and left first molars (Chi-Square = 400.003, P <0.001) between the age groups. Moreover, there was a significant difference in development of second right (Chi-Square = 398.070, P <0.001t and left (Chi-Square = 381.030, P <0.001) molars between the age groups.

Determining the frequency of developmental stages of the first and second homologous molars based on gender

According to the results of chi-square test, there was not a significant difference in developmental stage of right first molars between two genders (Chi-Square = 9.191, P=0.057) as well as left first molars between two genders (Chi-Square = 8.140, P=0.087). However, this difference was significant among right second molars (Chi-Square = 16.098, P=0.024). Moreover, there was a significant difference in developmental stage of left second molars among males and females (Chi-Square = 16.493, P=0.021).

Determining the frequency of developmental stages of the first and second homologous molars based on the four distributed age groups for each gender (total 8 groups)

According to the results of chi-square test, there is a significant difference in development of first right (Chi-Square = 416.517, P <0.001) and left molars (Chi-Square = 405.199, P <0.001) between the four distributed age group and gender. Moreover, there is a significant difference in development of right (Chi-Square = 449.731, P <0.001) and left (Chi-Square = 430.373, P <0.001) second molars between the four distributed age group and gender.

Skeletal maturity can be determined by using biological indicators such as height, weight, age, dental development, cervical vertebrae and finger and wrist bones, of which radiography of the fingers and wrist is the best and most reliable biological indicator (18, 19). However, this procedure requires a higher dose of radiation to prepare the wrist radiograph. Also, it imposes an additional cost on the patient. Accordingly, researchers are constantly striving to provide a safer and more reliable way to determine patients' skeletal maturity. One of these methods is to determine the evolution of mandible molar in panoramic radiography of patients. Development of teeth is extensively used for assessment of growth and age estimation. Several methods are available for assessment of tooth development and the Demirjian’s method is among the simplest and most practical methods for this purpose, which accuracy and validity have been confirmed in the Iranian race (20-24). Many researchers have used this method for assessment of dental development in different populations and have reported significant differences in dental development of different races. In a review study, Priyadarshiniet al. compared different methods for assessment of dental age and reported that the Demirjian’s method was the most efficient and simplest method for this purpose and is widely accepted worldwide. This method can be reliably standardized and has good intra- and inter-examiner reliability (25). This method is based on the assessment of mandibular teeth on panoramic radiographs since these teeth have less distortion on radiographs. In a study by Javadynejad et al, in 2008 on dental age estimation using panoramic radiography and Demirjian’s method, the accuracy of this method for estimation of chronological age of children in Isfahan was assessed. Comparison of chronological age and estimated age did not show a statistically significant difference. Thus, they concluded that the Demirjian’s method has high accuracy for estimation of age in children and this method can be used for determination of age especially in forensic medicine (23). In 2011, Bagherian et al. evaluated the accuracy of the Demirjian’s method and difference in dental maturity of Iranian and Canadian children. According to the difference between the estimated dental age and the chronological age, it seems that the Demirjian’s method is clinically applicable to the Iranian population (24). Thus, this study aimed to assess the developmental stage of homologous mandibular first and second molars in 5 to 12-year olds using the Demirjian’s method. The results of the current study showed that the difference in developmental stage of mandibular first molars was not significant in the right and left sides between two genders, but the second molars of the right and left sides were significantly different in terms of mineralization and developmental stage among females and males. Our results regarding the mandibular second molars are similar to those of previous studies (26-28) and in contrast with Zarabian et al, in 2018 who showed that the difference in developmental stage of mandibular second molars in the right and left side was not significant. Our findings showed there was a significant difference in the developmental stage of the first and second molars in the right and left side among different age groups. In order to compare the tooth development stages of homologues teeth using panoramic radiographs, the x-rays should have been taken during the time when teeth are under mineralization. The first permanent molars start to mineralize around birth and the crown is completed around three years of age (8). However, exposing young children to roentgen radiation, without individual indications, is not ethically acceptable (29). As discussed by Sahlstrand et al in 2013 and Zarabian et al in 2018, due to ethical issues panoramic radiographs cannot be taken of children in early stages of development of their first molars and this was a limitation of our study as well (29, 30). Therefore, existing panoramic radiographs of children from 5 to 12 years old, requested for other purposes were selected. In our selected age group, we could only assess the developmental stage of first and second molars. Another limitation of our study was selection of samples from a limited population presented to the Oral and Maxillofacial Radiology Department of Bandar Abbas University of Medical Sciences. Sampling from different populations may yield different results.

Within the limitations of this study, the results showed a significant difference in the developmental stage of the first and second molars in the right and left side among the disturbed age groups. According to the results, there was not a significant difference in the developmental stage of the first molars in right and left side between two genders while the difference in this regard between the mandibular right and left second molars between two genders was significant. Moreover, there was a significant difference in the development of the first and second molars in the right and left side between the four distributed age groups for each gender. A conclusion obtained from this study was that in the age group of 5 to 6 years, the development of the right second molar is later than the left side and there is a significant difference between the developmental stages in both sides. However, when the age group of 5 to 6 years were separated by gender, no difference was observed in development of right and left second molars within individual group.

Therefore, we concluded that gender is an impactful factor on the growth process of the second molar on the left and right in this age group. Future studies are required to assess the difference in the developmental stages of teeth in the right and left sides using methods other than the Demirjian’s method. Also, further studies on larger sample sizes selected from different populations are required to obtain more reliable results.

Ethics approval and consent to participates

All the radiographs used for this study were retrieved from the archive according to ethical guidelines. All methods were carried out in accordance with relevant guidelines and regulations. Also, written informed consent was obtained from the parents and the study was approved in the ethics committee of the Hormozgan University of Medical Sciences. All data were anonymised.

Consent for publication

Not applicable

Availability of data and materials

The datasets generated and/or analysed during the current study are available in the PDF file and can be requested from the corresponding author.

Competing interests

The authors declare that they have no competing interests.

Funding

None

Authors' contributions

1. Study concept and design: Aria Shamsi, Sara Esmaili, Gelareh Haghi Ashtiani

2. Acquisition of data: Aria Shamsi, Sara Esmaili

3. Analysis and interpretation of data: Aria Shamsi, Samira Mahmudi

4. Drafting of the manuscript: Aria Shamsi, Gelareh Haghi Ashtiani

5. Critical revision of the manuscript for important intellectual content: Gelareh Haghi Ashtiani

6. Statistical analysis: Samira Mahmudi

7. Administrative, technical, and material support: Sara Esmaili, Nasim Mokhtari

8. Figures and tables preparation: Aria Shamsi, Gelareh Haghi Ashtiani

Acknowledgements

The authors would like to thank the Research Deputy of Hormozgan University of Medical Sciences.

Conflict of Interest

None

Authors' information

1. Aria Shamsi, Department of Paediatric Dentistry, Dental School, Hormozgan University of Medical Sciences, Bandar Abbas, Iran

[email protected]

2. Sara Esmaili, Department of Paediatric Dentistry, Dental School, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.

[email protected]

3. Gelareh Haghi Ashtiani, (corresponding author)

Doctoral Researcher, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Turner Street, London E1 2AD, UK.

[email protected]

4. Nasim Mokhtari Asiistant Professor of Orak and Maxillofacial Radiology, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.

[email protected]

5. Samira Mahmudi Dental School, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.

[email protected]

Address for correspondence including email address

Gelareh Haghi Ashtiani, Doctoral Researcher, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Turner Street, London E1 2AD.

[email protected]

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No competing interests reported.

Assessment of mineralization and developmental stage of homologues mandibular first and second molars using panoramic radiographs and Demirjian's method in 5 to 12 years old children

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Abstract

Figures

Introduction

Materials And Methods

Results

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

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