The prevalence of dental caries among Egyptian children and adolescences and its association with age, socioeconomic status, dietary habits and other risk factors. A cross-sectional study

Introduction

Dental caries is a major public health issue and it is the most widespread chronic disease¹. Deciduous tooth decay was ranked as the 12^th most prevalent condition, affecting 560 million children in the 2015 Global Burden of Disease Study². Dental caries is a multifactorial disease, which can affect any age. It is highly related to and influenced by the patient’s dietary habits, sugar intake, salivary flow, salivary fluoride level and preventive behaviors. These factors, together with time, promote the microbial residence in the accumulated dental plaque to initiate dental caries¹.

In children, dental caries pattern depends on the timing of tooth eruption as well as harmful dietary habit. Therefore, age is considered as an important factor that affects dental caries prevalence in children³. Although caries is common, parents are infrequently concerned about oral health measures and usually poor oral health is linked with low socio-economic status⁴. Dental caries could only be prevented through addressing and changing the underlying etiological factors^5,6.

It has been estimated that about 60% to 90% of children at school age suffer from this chronic ailment^7,8. This percentage varies greatly in different population, with the incidence of dental caries in developing countries, including the Middle East, being much higher than its incidence in developed countries^9,10.

Despite the high prevalence of dental caries in the Egyptian population, only a few epidemiological studies of dental caries among Egyptians have been published. Moreover, most of the available data, are grey literature which are not available on common search engines^11–15. The most recently published epidemiological study on the oral health status in Egypt was held by WHO in collaboration with the Egyptian Ministry of Health in 2014¹⁶. Moreover, most of the epidemiological studies focused on children^17,18 and only one focused on adolescents¹⁹.

The prevalence of dental caries should be assessed continuously to plan and implement an efficient children oral health agenda and awareness programs for parents and school teachers in order to improve oral health. Therefore, this study was conducted to elucidate the prevalence of dental caries among Egyptian children and adolescence in correlation with age, socioeconomic level, dietary habits, oral hygiene measures and body mass index.

Subjects and methods

This study was carried out according to the regulations of the Research Ethics Committee of the Faculty of Dentistry, Cairo University, Egypt [Approval: 171217]. Written informed consent was obtained from children’s parents or guardians to participate in the study. Verbal consent was taken from adolescents in addition to written consent from their parent/guardian. The subjects in this study were recruited from the outpatients' clinics of Faculty of Dentistry, Cairo University and from two private nurseries in Nasr City and Maadi from 15th November 2017 to 13th January 2018. The inclusion criteria were; Age: starting from 3 years to 12 years for the children group, from 13 years to 18 years for adolescence; Gender: Males & Females; Ethnicity: Egyptians. The exclusion criteria were; Previous history/current radiotherapy and/or chemotherapy; Subjects undergoing orthodontic therapy, which might preclude normal tooth brushing; Subjects who, in the opinion of the Investigator, may be non-compliant with study procedures.

Results

II- dmft and different caries risk factors (Table 2, Figure 1)

Age was positively correlated with dmft (Spearman’s rho=0.32, p-value<0.0001). The highest mean dmft was for children aged between 5 to 6 years old (5.62 ±4.27) with a statistically significant difference between medians (p-value=0.0006).

Table 2. dmft and different risk factors - N= 369.

Variables	Categories - Mean (SD) / Median										Correlation		K-W test
1- Age	AI (3–4 years)		AII (5–6 years)		AIII (7–8 years)		AIV (9–11 years)		AV (12–17 years)		rho	p-value	p-value
	2.42 (3.71)	0 (0-16)	5.62(4.27)	4.5(0-18)	2.25(2.63)	2(0-5)	NA	NA	NA	NA	0.32	<0.0001*	0.0006*
2- Gender	Males					Females
	3.88(4.4)			3 (0-18)			2.68 (3.72)		1 (0-16)		-0.16	0.0483*	0.0486*
3- Body Mass Index	Underweight (<5)		Normal (≥5–<85)		Overweight (≥85–<95)			Obese (≥ 95)
	4.18(5.84)	0 (0-16)	3 (4.24)	1 (0-18)	2.87 (3.66)	1 (0-13)	3.48 (3.67)		3(0-12)		0.09	0.2742	0.6462
4- SES	Low			Moderate			High
	5.32 (3.63)	5 (0-16)	4.5 (4.99)		3 (0-18)		0.52 (1.4)		0 (0-8)		-0.64	<0.0001*	<0.0001*
5- Parental Education	Low			Moderate			High
	6.47(4.44)	6 (0-16)	4.47 (3.94)		4 (0-18)		1.41 (2.89)		0 (0-13)		-0.57	<0.0001*	<0.0001*
6- Biological Risks	No brushing		Infrequent		Once daily		Twice daily		Three times
-Parent own brushing	6 (5.4)	5 (0-16)	6.44(4.33)	6.5 (0-18)	2.06 (2.3)	1 (0-6)	1.64(2.39)	0 (0-10)	0.6(1.89)	0 (0-9)	-0.5	<0.0001*	<0.0001*
-Parent brushing for    child	5.18(4.72)	4.5(0-16)	5.97(4.19)	5 (0-18)	1.51 (2.3)	0 (0-8)	2.04(3.22)	0 (0-10)	0.06(0.24)	0 (0-1)	-0.5	<0.0001*	<0.0001*
-Child own brushing	4.58(4.57)	4 (0-16)	4.63(4.39)	4 (0-18)	2.65(3.15)	2 (0-10)	0.94(2.04)	2 (0-8)	0.06(0.24)	0 (0-1)	-0.47	<0.0001*	<0.0001*
7- Dietary Habits	≤ 2 times/week			3–6 times/week			1–6 times/day
-Bread	2.56 (4.5)	0 (0-16)	4.5 (6.36)		4.5 (0-9)		3.28 (4.02)		2 (0-18)		0.08	0.317	0.5142
-Other carbohydrates	4.62 (5.62)	2.5 (0-18)	1.96 (2.71)		0 (0-9)		3.4 (3.92)		2 (0-16)		0.04	0.576	0.0548
-Eggs	4.55 (4.44)	4 (0-18)	2.3 (3.45)		1 (0-14)		2.75 (3.92)		0 (0-16)		-0.21	0.0089*	0.0077*
-Fruits/Vegetables	5.71 (4.55)	5 (0-16)	2.61 (3.88)		1 (0-18)		2.61 (3.64)		1 (0-14)		-0.22	0.0046*	0.0006*
-Milk	4.87 (4.35)	4 (0-16)	4.33 (4.44)		4 (0-18)		2.38 (3.66)		0 (0-16)		-0.31	<0.0001*	0.0005*
-Milk products	5.11 (4.74)	4 (0-16)	2.35 (2.99)		1 (0-9)		2.71 (3.82)		1 (0-18)		-0.2	0.0093*	0.008*
-Grains	2.7 (4)	0 (0-18)	4.6 (4.5)		4 (0-16)		3.64 (4.01)		3 (0-16)		0.18	0.0206*	0.0366*
-Jam, Molasses,    Honey	3.46 (4.32)	2 (0-18)	1.48 (2.69)		0 (0-8)		3.97 (4.04)		4 (0-14)		0.04	0.9561	0.0073*
-Candies	1.86 (3.05)	0 (0-12)	3.72 (4.38)		2 (0-13)		4.21 (4.45)		3.5 (0-18)		0.29	0.0002*	0.0012*
-Crackers	1.8 (3.08)	0 (0-13)	2 (2.45)		1.5 (0-7)		4.3 (4.49)		4 (0-18)		0.3	0.0001*	0.0008*
-Junk food	2.99 (3.76)	1 (0-16)	3 (NA)		3 (3-3)		5.11 (5.85)		3.5 (0-18)		0.1	0.2092	0.45
-Chocolate	2.03 (3.18)	0 (0-13)	3.5 (2.78)		4 (0-8)		5.02 (5.02)		4 (0-18)		0.34	<0.0001*	<0.0001*
-Soda drinks	2.97 (4)	1 (0-18)	4.25 (3.28)		4.5 (0-12)		3.54 (4.54)		1 (0-16)		0.07	0.413	0.1315
-Juices	3.35 (4.03)	2 (0-18)	3.52 (4.63)		1 (0-14)		3.01 (3.97)		1 (0-16)		-0.04	0.5759	0.8527
-Citric juices	3.19 (3.92)	2 (0-18)	2.75 (3.87)		0 (0-12)		3.81 (4.93)		1 (0-16)		-0.01	0.9162	0.6387
-Caffeinated drinks	3.13 (3.61)	2 (0-16)	5 (NA)		5 (NA)		3.32 (4.56)		1 (0-18)		-0.04	0.6431	0.6342

The correlation coefficient, rho, ranges from -1 to +1. Where 1= perfect positive correlation, 0=no correlation, -1 = perfect negative (inverse) correlation. *Statistical significance at p-value ≤ 0.05

Figure 1. dmft and different risk factors - N= 369: *+ve correlations; ** inverse correlations; A: ≤ 2 times/week B: 3–6 times/week C: 1–6 times/day.

Gender, SES and parental educational were inversely correlated with dmft (Spearman’s rho=-0.16, -0.64, -0.57, p-value=0.0483, <0.0001, <0.0001) respectively. Male children, children with low SES and children with low level of parental education had the highest mean dmft (3.88 ±4.4, 5.32 ±3.63, 6.47±4.44) with statistically significant difference (p-value= 0.0486, <0.0001, <0.0001) respectively.

BMI was not correlated with dmft (Spearman’s rho=0.09, p-value=0.2742) and the highest mean dmft was for underweight children (4.18 ±4.27). The difference in medians was statistically insignificant (p-value >0.05).

dmft of children increased with decreased brushing frequency of parents, brushing frequency of parents to their children and children’s own brushing frequency (Spearman’s rho= - 0.5, p-value<0.0001) and the highest mean dmft were with infrequent brushing (6.44 ±4.33, 5.97 ±4.19, 4.63 ±4.39) respectively. The difference in medians was statistically significant (p-value<0.0001).

Positive correlations exist between dmft and the consumption of candies, crackers, chocolate and beans (rho=0.29, 0.3, 0.34, 0.18, p-value=0.0002, 0.0001, <0.0001, 0.0206) with highest mean dmft with frequency 1–6 times per day for candies, crackers, chocolate (4.21±4.45, 4.3±4.49, 5.02 ±5.02) respectively and 3–6 times per week for beans (4.6±4.5). Negative correlations occur between dmft and the consumption of eggs, fruits/vegetables, milk and milk products (rho= -0.21, -0.22, -0.31, -0.2, p-value=0.0089, 0.0046, <0.0001, 0.0093) with highest mean dmft with frequency ≤ 2 times/week (4.55±4.44, 5.71±4.55, 4.87 ±4.35, 5.11 ±4.74) respectively. No correlation was found between dmft and the consumption of bread, other carbohydrates, jams, junk food, soda, juices, citric juices and caffeinated drinks (p-value>0.05).

III- deft and different caries risk factors (Table 3, Figure 2)

The highest mean deft was for children aged between 5 to 6 years old, children with low SES and children of patients with low level of parental education (5.51 ±3.28, 4.68 ±3.24, 4.62 ±3.25). The differences in medians were statistically significant for age and SES (p-value= 0.0013, 0.0277), while borderline insignificant for parental education (p-value=0.0542). Age, SES and parental education were inversely correlated with deft in children (Spearman’s rho= -0.42, -0.19, -0.16, p-value<0.0001, 0.0123, 0.0354).

Table 3. deft and different risk factors - N= 369.

Variables	Categories - Mean (SD) / Median										Correlation		K-W test
1- Age	AI (3–4 years)		AII (5–6 years)		AIII (7–8 years)		AIV (9–11 years)		AV (12–17 years)		rho	p-value	p-value
	4 (NA)	4 (NA)	5.51(3.28)	5 (0-14)	5.22 (3.24)	4.5(0-13)	3.06 (2.5)	3 (0-12)	1.95 (2.5)	1 (0-9)	-0.42	<0.0001*	0.0013*
2- Gender	Males					Females
	4.04(2.93)		4 (0-14)		4.34 (3.41)			4 (0-13)			0.01	0.8758	0.8752
3- Body Mass Index	Underweight (<5)		Normal (≥5–<85)		Overweight (≥85–<95)			Obese (≥ 95)
	3.67(2.27)	4 (0-7)	4.19 (3.13)	4 (0-13)	4.73 (3.65)	4.5 (0-14)	4.19 (3.33)		4 (0-12)		0.03	0.7132	0.9166
4- SES	Low			Moderate			High
	4.68 (3.24)	4 (0-13)	3.78 (2.9)		4 (0-13)		2.81 (4.14)		1 (0-14)		-0.19	0.0123*	0.0277*
5- Parental Education	Low			Moderate			High
	4.62 (3.25)	4 (0-12)	4.49 (2.95)		4 (0-13)		3.55 (3.47)		3 (0-14)		-0.16	0.0354*	0.0542
6- Biological Risks	No brushing		Infrequent		Once daily		Twice daily		Three times
-Parent own    brushing	4.65(2.75)	4(0-13)	4.5(3.12)	4(0-13)	3.38(3.31)	3(0-13)	4.29(3.95)	3(0-14)	4.5 (2.89)	4.5(1-8)	-0.14	0.0815	0.2237
-Parent brushing    for child	5.3 (3.34)	5 (0-13)	4.1(2.75)	4 (0-12)	4.88(3.84)	4.5(0-14)	3.3 (2.75)	3 (0-8)	3 (2.65)	4 (0-5)	-0.17	0.0456*	0.3299
-Child own    brushing	4.91(2.62)	5 (0-10)	4.25(3.01)	4 (0-14)	4.1 (3.45)	4 (0-13)	1.29(1.33)	1 (0-4)	1.67(2.89)	0 (0-5)	-0.31	0.0001*	0.0003*
7- Dietary Habits	≤ 2 times/week			3–6 times/week			1–6 times/day
-Bread	3.3 (2.98)	2.5 (0-13)		10 (2.83)		10 (8-12)		4.26 (3.17)		4 (0-14)	0.06	0.4074	0.0484*
-Other    carbohydrates	4.44 (2.8)	4 (0-11)		4.12 (2.65)		4 (0-12)		4.15 (3.55)		3 (0-14)	-0.08	0.285	0.5628
-Eggs	4.18 (2.99)	4 (0-13)		3.77 (3.61)		3 (0-13)		4.71 (3.49)		4 (0-14)	0.01	0.8893	0.3922
-Fruits/Vegetables	5.6 (3.2)	5 (0-13)		4.05 (2.69)		4 (0-10)		3.09 (3.12)		2 (0-14)	-0.36	<0.0001*	<0.0001*
-Milk	4.43 (3.19)	4 (0-13)		5.3 (2.6)		5 (0-9)		3.49 (3.33)		3 (0-14)	-0.12	0.119	0.0171*
-Milk products	4.59 (2.8)	4 (0-12)		4.39 (3.19)		4.5 (0-12)		3.89 (3.48)		3 (0-14)	-0.15	0.0527	0.1501
-Grains	4.01 (3.11)	4 (0-14)		4.5 (3.06)		4 (0-10)		4.35 (3.37)		4 (0-13)	0.04	0.6093	0.7777
-Jam, Molasses,    Honey	4.38 (3.37)	4 (0-14)		3.88 (2.78)		3 (0-10)		3.96 (3.02)		4 (0-13)	-0.05	0.5366	0.8115
-Candies	2.96 (2.93)	2 (0-12)		3.47 (2.38)		3 (0-9)		4.86 (3.27)		4 (0-14)	0.29	0.0001*	0.0009*
-Crackers	2.22 (2.77)	2 (0-14)		3.73 (1.56)		4 (1-6)		4.77 (3.23)		4 (0-13)	0.34	<0.0001*	<0.0001*
-Junk food	4.06 (3.27)	4 (0-14)		4.77 (3.22)		4 (1-12)		4.78 (2.89)		5 (0-10)	0.13	0.1046	0.2675
-Chocolate	3.89 (3.19)	3 (0-13)		4.58 (3.53)		4 (0-14)		4.42 (3.15)		4 (0-13)	0.09	0.2277	0.4079
-Soda drinks	4.21 (3.18)	4 (0-13)		4.9 (3.97)		5 (0-14)		3.92 (2.86)		4 (0-10)	-0.01	0.9181	0.6463
-Juices	3.73 (2.68)	3 (0-12)		4.28 (2.39)		4 (0-8)		5.02 (4.06)		4.5 (0-14)	0.14	0.0823	0.2094
-Citric juices	3.9 (3.03)	4 (0-14)		4.27 (2.91)		4 (0-10)		6.32 (3.96)		7 (0-13)	0.18	0.019*	0.0339*
-Caffeinated drinks	4.17 (3.13)	4 (0-13)		2.6 (3.58)		0(0-7)		4.43 (3.34)		4 (0-14)	0.04	0.6383	0.4162

The correlation coefficient, rho, ranges from -1 to +1. Where 1= perfect positive correlation, 0=no correlation, -1 = perfect negative (inverse) correlation.

*Statistical significance at p-value ≤ 0.05.

Figure 2. deft and different risk factors - N= 369: *+ve correlations; ** inverse correlations; A: ≤ 2 times/week B: 3–6 times/week C: 1–6 times/day.

The highest mean deft was for females (4.34 ±3.41) and overweight children (4.73 ±3.65). The difference in medians was statistically insignificant (p-value>0.05) and correlation coefficients revealed no correlation between deft and either gender or BMI (Spearman’s rho=0.01, 0.03, p-value=0.8758, 0.7132).

The highest mean deft was for children whose parents don’t brush their own teeth (4.65 ±2.75), or their children teeth (5.3 ±3.34), or children who don’t brush their own teeth (4.91 ±2.62). The difference in medians were statistically insignificant for parents own brushing frequency and brushing frequency to their children’s teeth (p-value>0.05), while it was statistically significant for children’s own brushing frequency (p-value= 0.0003). The correlation coefficient revealed no correlation between deft and parents own brushing frequency (rho= -0.14, p-value=0.0815), while inverse correlation with parents brushing frequency to their children’s teeth and children own brushing frequency (rho= -0.17, -0.31, p-value=0.0456, 0.0001).

The highest mean deft was for children who consume candies, crackers, junk food, juices, citric juices and caffeinated drinks 1–6 times per day (4.86±3.27, 4.77±3.23, 4.78± 2.89, 5.02±4.06, 6.32±3.96, 4.43±3.34) and children who consume bread, beans, chocolates and soda 3–6 times per week (10±2.83, 4.5±3.06, 4.58±3.53, 4.9±3.97), as well as children who consume other carbohydrates and jams less than or equal to two times a week (4.44 ±2.8, 4.38±3.37). The lowest mean deft was for children who consume eggs 3-6 times per week (3.77 ±3.61) and children who consume fruits/vegetables, milk and milk products 1–6 times per day (3.09 ±3.12, 3.49 ±3.33, 3.89±3.48) respectively.

The differences in medians for deft with fruits/vegetables, candies, crackers and citric juices consumption were statistically significant. There were positive correlations between candies, crackers, citric juices consumption and deft of children (rho=0.29, 0.34, 0.18, p-value=0.0001, <0.0001, 0.019), while there was inverse correlation between fruits/vegetables and deft (rho= -0.36, p-value <0.0001). No correlation was detected between deft of children and the consumption of bread, other carbohydrates, eggs, milk, milk products, beans, jams, junk food, chocolates, soda, juices and caffeinated drinks (p-value>0.05).

III- DMFT and different caries risk factors (Table 4, Figure 3)

The highest mean DMFT was for adolescents aged between 12 to 17 years (1.68 ±1.92). The difference in medians was statistically significant (p-value= <0.0001). Age was positively correlated with DMFT (Spearman’s rho=0.36, p-value<0.0001).

Table 4. DMFT and different risk factors - N= 369.

Variables	Categories - Mean (SD) / Median										Correlation		K-W test
1- Age	AI (3–4 years)		AII (5–6 years)		AIII (7–8 years)		AIV (9–11 years)		AV (12–17 years)		rho	p-value	p-value
	NA	NA	0.32 (0.9)	0 (0-4)	0.59 (1)	0(0-4)	1.2 (1.55)	0(0-5)	1.68 (1.92)	1(0-8)	0.36	<0.0001*	<0.0001*
2- Gender	Males					Females
	1.28 (1.9)		0(0-8)		0.88 (1.28)			0 (0-5)			-0.05	0.4363	0.435
3- Body Mass Index	Underweight (<5)		Normal (≥5–<85)		Overweight (≥85–<95)			Obese (≥ 95)
	1 (2.33)	0(0-8)	1.15 (1.52)	0 (0-6)	0.53 (1.34)	0(0-6)	1.02 (1.4)		0(0-5)		-0.04	0.5794	0.0353*
4- SES	Low			Moderate			High
	1.13 (1.67)	0(0-8)	0.92 (1.42)		0 (0-6)		1.29 (1.73)		0 (0-5)		-0.02	0.7829	0.7764
5- Parental Education	Low			Moderate			High
	1.45 (1.93)	1(0-8)	0.89 (1.43)		0 (0-6)		0.93 (1.42)		0(0-6)		-0.07	0.2968	0.2141
6- Biological Risks	No brushing		Infrequent		Once daily		Twice daily		Three times
-Parent own brushing	1.28(1.78)	0 (0-5)	1.1(1.59)	0 (0-6)	0.75(1.14)	0(0-6)	1.19(1.57)	0 (0-5)	1.6 (3.58)	1(0-8)	-0.03	0.648	0.8016
-Parent brushing for    child	1.11(1.58)	0 (0-5)	0.88(1.53)	0 (0-6)	1.19(1.86)	0 (0-8)	1.18(1.78)	1 (0-6)	0 (0)	0 (0-0)	-0.02	0.8413	0.6872
-Child own brushing	1.19(1.47)	1 (0-4)	1.31(1.85)	0 (0-8)	1 (1.67)	0 (0-6)	0.85(1.25)	0 (0-5)	1.25 (1.5)	1 (0-3)	-0.08	0.2909	0.7799
7- Dietary Habits	≤ 2 times/week			3–6 times/week			1–6 times/day
-Bread	1.25 (1.83)		0 (0-5)		1 (1.41)		1 (0-2)		1.02 (1.53)	0 (0-8)	-0.02	0.7909	0.957
-Other    carbohydrates	1.12 (1.55)		0 (0-5)		1.32 (1.95)		0 (0-8)		0.93 (1.43)	0 (0-6)	-0.05	0.4446	0.677
-Eggs	1.07 (1.52)		0 (0-8)		1.18 (1.78)		0 (0-6)		0.77 (1.44)	0 (0-5)	-0.09	0.1799	0.307
-Fruits/Vegetables	1.23 (1.68)		0 (0-6)		1.08 (1.9)		0 (0-8)		0.9 (1.27)	0 (0-5)	-0.03	0.6737	0.6704
-Milk	1.15 (1.55)		0 (0-6)		0.96 (2.06)		0 (0-8)		0.95 (1.43)	0 (0-6)	-0.05	0.4692	0.3403
-Milk products	1.19 (1.79)		0 (0-8)		1.13 (1.61)		0 (0-5)		0.93 (1.41)	0 (0-6)	-0.04	0.592	0.8569
-Grains	0.93 (1.53)		0 (0-6)		1.57 (2.47)		0 (0-8)		1.06 (1.44)	0 (0-5)	0.08	0.2462	0.4485
-Jam, Molasses,    Honey	1.06 (1.6)		0 (0-8)		1.3 (1.72)		0.5 (0-6)		0.86 (1.37)	0 (0-5)	-0.02	0.7349	0.5833
-Candies	0.86 (1.54)		0 (0-5)		1.38 (2.16)		0 (0-8)		1.05 (1.46)	0 (0-6)	0.08	0.2202	0.2972
-Crackers	0.73 (1.08)		0 (0-4)		1.59 (2.43)		0 (0-8)		1.22 (1.6)	0 (0-6)	0.06	0.4088	0.5112
-Junk food	1.05 (1.61)		0 (0-8)		0.87 (1.3)		0 (0-4)		0.93 (1.31)	0 (0-5)	-0.01	0.9314	0.9739
-Chocolate	0.83 (1.48)		0 (0-8)		1.18 (1.78)		0 (0-6)		1.3 (1.56)	1 (0-6)	0.16	0.0178*	0.0584
-Soda drinks	0.98 (1.54)		0 (0-8)		1.25 (1.75)		0 (0-5)		1.09 (1.55)	0 (0-6)	0.05	0.5166	0.7974
-Juices	0.98 (1.52)		0 (0-6)		1.86 (2.23)		1.5 (0-8)		0.9 (1.34)	0 (0-6)	0.02	0.7458	0.1589
-Citric juices	1.03 (1.51)		0 (0-6)		1.4 (2.23)		0 (0-8)		0.68 (1.11)	0 (0-4)	-0.03	0.6481	0.7295
-Caffeinated drinks	1 (1.61)		0 (0-6)		1.5 (1.77)		1 (0-4)		1.04 (1.48)	0 (0-8)	0.07	0.2849	0.427

The correlation coefficient, rho, ranges from -1 to +1. Where 1= perfect positive correlation, 0=no correlation, -1 = perfect negative (inverse) correlation. *Statistical significance at p-value ≤ 0.05.

Figure 3. DMFT and different risk factors - N= 369: *+ve correlations; ** inverse correlations; A: ≤ 2 times/week B: 3–6 times/week C: 1–6 times/day.

Males and children within the normal range for BMI had the highest mean DMFT (1.28 ±1.9, 1.15 ±1.52) respectively. The difference in medians was statistically insignificant for gender (p-value>0.05) and statistically significant (p-value=0.0353) for BMI. Correlation coefficient revealed no correlation between gender and BMI with DMFT (Spearman’s rho= -0.05, -0.04, p-value=0.4363, 0.5794).

The highest mean DMFT was for children with high SES and low parental education (1.29 ±1.73, 1.45 ±1.93). The differences in medians were statistically insignificant (p-value>0.05) and correlation coefficients were also insignificant (Spearman’s rho= -0.02, -0.07, p-value=0.7829, 0.2968).

The highest mean DMFT was for children whose parents brush their own teeth three times a day (1.6 ±3.58) and their child’s teeth once a day (1.19 ±1.86) as well as for children who don’t brush their teeth (1.19±1.47). The differences in medians for DMFT were statistically insignificant (p-value>0.05) and there was no correlation between DMFT and any of the biological risk factors.

The highest mean DMFT was for children who consume chocolates 1-6 times per day (1.3±1.56) and children who consume other carbohydrates, eggs, beans, jams, candies, crackers, soda, juices, citric juices and caffeinated drinks 3-6 times per week (1.32±1.95, 1.18±1.78, 1.57±2.47, 1.3±1.72, 1.38±2.16, 1.59±2.43, 1.25±1.75, 1.86±2.23, 1.4±2.23, 1.5±1.77) respectively as well as for children who consume bread, fruits/vegetables, milk, milk products and junk food less than or equal to two times a week (1.25±1.83, 1.23 ±1.68, 1.15±1.55, 1.19 ±1.79). The differences in medians with all the investigated dietary elements were statistically insignificant (p-value>0.05) and there was no correlation between DMFT and any of them except chocolate that had a positive correlation with DMFT (rho=0.16, p-value=0.0178) despite the difference in medians being borderline statistically insignificant (p-value=0.0584).

Discussion

The high prevalence of dental caries is not only influenced by the biological factors that interact with the causative microorganisms, but it is also associated with socioeconomic, educational conditions and dietary habits³¹. Dental caries is considered a major public health problem in underdeveloped or developing countries like Egypt. Therefore, investigating the risk factors associated with it has become a major concern to researchers who seek strategies for controlling or preventing the disease.^31,32.

This study investigated the prevalence of dental caries in a wide age range of children because as individuals grow, their dietary needs and habits constantly change. The prevalence of dental caries among Egyptian children was higher in primary dentition (dmft and deft) when compared to permanent dentition (DMFT), this is similar to what has been reported in India^33,34. Deciduous teeth have a higher susceptibility to dental caries due to the lower calcium content and structural differences³⁵. Moreover, caries in the primary dentition could be associated with under nutrition during early childhood. Macro and micro tooth morphology, chemical composition and eruption pattern could be affected by nutrients like vitamin A, vitamin D, calcium and phosphorus³⁶.

In the current study, there was a significant positive correlation between dmft and age, which is in agreement with previous studies conducted in Brazil and Colombia among children aged between 3 to 5 years^37,38. On the other hand, age was inversely correlated with deft in Egyptian children as in mixed dentition period, the maintenance of oral hygiene is difficult due to shedding of primary teeth and pubertal changes.

Investigating the effect of gender on dental caries in the present study revealed that the mean dmft and DMFT of males were higher than those of females while the mean deft of females was slightly higher than that of males. Spearman’s test revealed an inverse correlation between gender and dmft, while no correlation with deft and DMFT. This is similar to a study carried out in Kerala on children aged 12–15 years old, where boys and girls were almost equally affected by caries³⁹, while differs from another cross-sectional study carried on 10-11 years old Italians, where a significant difference was found between DFT of boys (3.20) and DFT of girls (1.96)⁴⁰. It has been demonstrated that dental caries prevalence switches from male to females with age, where in the 5-year-old age group 47.4% of children with caries were male, while 41.1% were female. On the other hand, in the 12-year-old age group the percentage was inversed (24.1% female versus 20.6% male)⁴¹.

Up to date there is a limited evidence clarifying the association between nutritional status and oral health. According to our results, there was no statistically significant correlation between BMI and any of the caries indices. This is inagreement with the findings from previous studies in Taiwan and in Sweden^42,43. Oliveira et al. in Brazil⁴⁴, concluded that underweight children were more likely to have caries which is in accordance with our findings where the highest mean dmft was recorded in underweight children (4.18±4.27). The recorded non significant correlation between DMFT and BMI is consistent with the findings of a previous study among adolescents aged 12 years in public and private schools in São Paulo State⁴⁵, meanwhile, it is opposite to a study in a German elementary school⁴⁶ which reported an increase in the DMF with increased BMI. However, in the present investigation a positive association between BMI and deft was recorded, but this was not at a statistically significant level (p=0.9166) which is similarly reported by Elangovan et al.⁴⁷.

Parents play a significant role in the development of their children's oral hygiene habits⁴⁸. Parental education level, which is directly associated with socioeconomic status⁴⁹, greatly affects the child's oral health⁵⁰. In the current study, there was an inverse significant correlation between parental educational level, socioeconomic status and dmft in children which is in accordance with previous studies that reported this correlation in early years^44,51,52. Low socioeconomic status is usually accompanied by poor dietary habits and unhealthy lifestylesthat contribute to the development of dental caries^53–57. Meanwhile, parents with high socioeconomic and education levels start taking care of their children’s dental health before their second year of life and help them brush their teeth, as reported in a German cross-sectional study⁵⁸. As the child grows, the parental impact decreases and parents may totally lose their control on the child’s dietary habits and oral hygiene measures. This explains the non-significant correlation between DMFT and parental education, as well as socioeconomic level. Moreover, it has been reported in a study carried out on Indian adolescences that area of residence appears to be a significant determinant for an adolescent to be caries/decay free. Psychosocial and behavioral factors do not mediate the same association⁵⁹. Since, parents' attitude is the principal social force influencing the child’s development in the early childhood years, therefore parental oral health beliefs and practices may be helpful in the prevention of oral health diseases such as caries⁶⁰. This is concomitant with our findings where dmft and deft in Egyptian children were correlated to parental brushing to the child and with the child’s own brushing frequency. Children who received oral health education from their parents started to brush their teeth at an earlier age which revealed better dental health⁶¹.

Studies that aim to establish the relationship between eating habits and the development of caries preferentially use frequency of food consumption questionnaires such as that employed in our study^62,63. The relationship between the development of carious lesions and dietetic factors has been investigated since the 1940s. It has been suggested that the relationship between sugar intake and the development of carious lesions is currently different from that documented in the past decades, since dental health has improved greatly in the developed countries, with no parallel decrease in the consumption of sugar and cariogenic foods⁶⁴.

The prevalence of dental caries in view of our results was significantly positively correlated with chocolate, candies and crackers consumption. A direct linkage between sugar intake and caries has been reported previously as cariogenic bacteria grow with the presence of fermentable carbohydrates^65,66. Higher chocolate consumption led to increased caries indices which is consistent with the results from other studies^67,68. Consumption of candies more than once per week, besides insufficient oral hygiene measures have been claimed to be risk factors for caries development in primary and permanent dentition⁶⁹. Candies remain on the tooth surface for hours and don't have any nutritional value⁷⁰.

Citric juices were also found to be positively correlated with dental caries in primary teeth in Egyptian children. Hydroxyapatite crystals start to dissolve when the pH reaches 5.5 and enamel begins to be at risk of decalcification. Subsequently, acidic drinks have been reported to play a significant role in the pathogenesis of dental erosion^71–75.

The inverse significant correlation between fruits/vegetables consumption and caries agrees with a study which recorded that dental caries prevalence was higher in non-vegetarians in comparison with vegetarians⁷⁶. This correlation could be attributed to a lesser tendency for sweets between meals in vegetarians compared with non-vegetarians⁷⁷. In addition Egyptian children who consumed milk more frequently had lower caries experience. Milk has low cariogenic potential and contains cariostatic factors against dental caries⁷⁸. Studies showed that milk contains potential caries protective factors as calcium, phosphorus and casein^79,80. The variability of milk consumption manner and other factors may result in a positive association between milk and dental caries occurrence⁸⁰. This was proven when the frequency of milk consumption did not show a significant association with caries (DMFT).

The insignificant correlations recorded in the current work between all dental caries indices and bread, other carbohydrates, junk food, jam, molasses, honey and juice consumption could be referred to the cross-sectional design of the study. The cross-sectional study may not accurately reflect the true dietary habits of the children before the dental caries occurred since old dietary habits may be responsible for the current development of caries⁸¹.

Soda consumption frequency recorded a non-significant correlation with dental caries. This disagrees with past studies which have reported positive correlation between soft drinks and dental caries^82–84. Although sugars in soft drinks lead to drop in the pH of dental plaque and saliva, salivary components can neutralize the acids within 20-30 minutes raising the pH of plaque to its resting level⁸⁵. Despite the fact that no correlation was found between caffeinated drinks consumption and caries, it was reported that polyphenols in coffee and tea can reduce the cariogenic potential of foods⁸⁶. Coffee is active against Streptococcus Mutans, the organism causing dental caries. Roasted coffee also has anti-adhesive properties. In this manner, it prevents adhesion of Streptococcus Mutans to the teeth⁸⁷.

Finally it could be concluded that in primary dentition, the caries incidence in Egyptian children was positively correlated with candies and crackers while inversely correlated with SES, parental education, brushing frequency of the parent to the child, brushing frequency of the child to him/herself and fruits/vegetables consumption. In permanent dentition DMFT was only significantly positively correlated with age and chocolates.

The World Health Organization emphasizes the need public health solutions for prevention of dental caries. Therefore, the following recommendations based on the results of the current study should be added to the WHO policy measures⁸⁸ to promote the reduction of dental caries prevalence in Egypt: 1- Candies and crackers should be prohibited for children before 12 years old; 2- Children should be encouraged to eat fruits and vegetables; 3- Awareness campaigns should be carried out to encourage the parents to brush their children’s teeth and to encourage the children to brush their own teeth.

The non-significant differences and lack of correlations between some caries indices and risk factors could be attributed to the small sample size, with a larger set of samples they may have reached statistical significance. In addition, a larger population from different governorates may have allowed broader diversity for better representation for Egyptian population.

Data availability

Underlying data is available from Figshare.

Figshare: Dataset 1. Raw data for caries incidence in correlation to risk factors in Egyptian children. https://doi.org/10.6084/m9.figshare.7445843.v1⁸⁹

License: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication