The occurrence of periodontal diseases and its correlation with different risk factors among a convenient sample of adult Egyptian population: a cross-sectional study

Study design and participants

This study was carried out according to the regulations of the Ethics Committee, Faculty of Dentistry, Cairo University, Egypt (approval: 171217). Convenience sample was utilized in this study. Eligible patients were recruited according to the inclusion and exclusion criteria over a period of two months, starting from the 16th of August 2018 until the 18th of October 2018. Patients were recruited from the outpatient clinics at the Faculty of Dentistry, Cairo University, as well as three private dental offices (Cairo Dental Clinic, Specialized Dental Clinic and El-Rahamn Medical Center). Patients were asked directly to participate in the study while they were attending the clinics. Written consent was obtained from the patients to perform the examinations and for the use and publication of their anonymized data. The inclusion criteria were as follows: age: 18–74 years; gender: males and females; ethnicity: Egyptians. Exclusion criteria were smokers; previous history of/current radiotherapy and/or chemotherapy; pregnant or lactating females; edentulous patients; patients undergoing orthodontic therapy; patients with aggressive periodontitis; patients who had undergone periodontal treatment (including prophylaxis) and/or antibiotic therapy over the past three months.

Sample size calculation

According to the following simple formula⁸: $n\text{'}=\frac{N{Z}^{2}P(1–P)}{d^2(N–1)+Z^{3}P(1–P)}$

Where n' = sample size with finite population correction, N = population size, Z = Z statistic for a level of confidence which is conventional (Z value is 1.96), p = expected prevalence and d = precision (5%, d = 0.05). The sample size was estimated to be 339 as the population of Egypt was considered to be 90,000,000, as estimated by the World Bank. The prevalence was estimated to be 32% by averaging the prevalence in India and Bangladesh of 17.5 –21.4%⁹ and 45% in India¹⁰.

Data collection and grouping

Data were collected using a questionnaire that has previously been used in other studies^11,12 with questions on age, sex, occupation, address, level of education and dietary habits (provided as Extended data)¹³. The questionnaire was filled out by the examiners in the clinics. A Beurer scale (Ulm, Germany) was used to measure body weights with individuals wearing clothing but no shoes. Standing heights were obtained. Body mass index (BMI) was calculated from measured height and weight data. Subjects were classified into the following groups: underweight (BMI<18.5 kg/m²); normal weight (BMI 18.5–24.9 kg/m²); overweight (BMI 25.0–29.9 kg/m²); obese (BMI ≥30.0 kg/ m²). Moreover, patients were categorized into low, moderate and high socioeconomic subgroups based on their education level, occupation, address and the health center where they received their treatments according to a validated socioeconomic status scale for health research in Egypt¹⁴.

Oral examination

Clinical and radiographic case identification was performed by trained examiners (MM and NY) to reach a consensus according to the latest classification of periodontal diseases that was described in 2018^15,16. The clinical outcomes were the assessment of the presence or absence of calculus and the stage of periodontitis. In order to define the stage of periodontitis, pocket depth (PD) and clinical attachment level (CAL) were measured using a Williams periodontal probe. Periodontitis was categorized into four stages (Table 1)¹⁶.

Statistical analysis

Data were statistically described in terms of number of cases and percentages. Comparison between the study groups was done using ANOVA test with post-hoc multiple two-group comparisons. For comparing categorical data, Chi-square (χ²) test was performed. Correlation between variables was done using Spearman rank correlation equation. p values <0.05 were considered statistically significant. All statistical calculations were done using IBM SPSS (Statistical Package for the Social Science; IBM Corp, Armonk, NY, USA) release 22 for Microsoft Windows.

Population profile

The number of individuals at each stage of the study are shown in Figure 1 and the number and percentage of patients in different categories are presented in Table 2. It was found that 24.5% of participants brush their teeth twice daily, while 23.3% don’t brush their teeth¹⁷. The occurrence of calculus was 58.9%. The occurrence of periodontitis was 89.8%, where 70.8.5% of participants had stage I periodontitis and 15.2% had stage II, while 4.4.% and 2.04% of participants had stage III and stage IV, respectively.

Figure 1. Flow chart of patient selection.

Correlation between calculus and different risk factors

As shown in Table 3, the highest percentage of calculus among different age groups was recorded in adults aged 50–70 years (70%). A comparison of the occurrence of calculus between age subgroups revealed a statistically significant difference (p =0.001). There was a positive correlation between age and calculus (rho=-0.192, p <0.001).

Regarding gender and BMI, males and obese adults had the highest incidence of calculus (55.4% and 65.8%, respectively). A comparison of the occurrence of calculus between gender subgroups as well as a comparison between BMI subgroups were statistically insignificant (p ≥0.05). There was no correlation between either of these factors and calculus (rho=-0.086, p=0.111 and rho=-0.101, p =0.062, respectively).

Regarding SES, education level and brushing frequency, adults with a low SES, a low educational level and those who don’t brush their teeth had the highest occurrence of calculus (72.3%, 80% and 78.8%, respectively). A comparison of calculus occurrence between SES, education level and brushing frequency subgroups revealed a statistically significant difference (p=<0.05) and there was an inverse correlation between these factors and calculus (rho=-0.254, p<0.001; rho=-0.167, p=0.002; and rho=-0.326, p <0.001, respectively).

Adults who consume bread, carbohydrates other than bread, eggs, fruits and vegetables, milk, milk products, candies and citrus juices less than or equal to two times a week had the highest occurrence of calculus compared to those who consumed these products more frequently (87.5%, 60.8%, 61.3%, 69.1%, 65%, 60.8%, 61.8% and 60.8%, respectively). Those who consume grains, sugars in drinks, sugar not in drinks, jams, crackers, junk food, chocolates, juices and caffeinated drinks with a frequency of one to six times per day had the highest occurrence of calculus (65.4%, 62.8%, 65.1%, 59%, 61.8%, 60.4%, 63.3%, 60.4% and 60.8%, respectively), as well as those who consume soda three to six times per week (62.8%).

A comparison of calculus occurrence between consumption frequency subgroups for all dietary elements was statistically insignificant except for milk, grains and sugars in drinks (p<0.05). There was a positive correlation between consumption frequency of grain, sugars in drinks and calculus (rho=0.133, p=0.014 and rho=0.139, p=0.010, respectively), while milk revealed an inverse correlation (rho= -0.133, p =0.013).

Correlation of periodontitis and different risk factors

As it is revealed in Table 3, the highest occurrence of periodontitis among different age groups (96.7%) was recorded among adults aged (50–70 years). In all age groups, the majority of participants suffered from stage I periodontitis: 70.5% of adults aged 18–34 years; 66.3% of adults aged 35–49 years; and 63.3% of adults aged 50–70 years. A comparison of periodontitis occurrence between age subgroups revealed a statistically significant difference (p=0.005). There was a positive correlation between age and periodontitis (rho=0.206, p=<0.001).

The highest percentage of periodontitis was recorded among males (92.1%), while in females the occurrence was 88.2 %. Stage I periodontitis was predominant, with 64.7% of males and 70.6% of females with this stage of periodontitis. A comparison of periodontitis occurrence between gender subgroups showed a statistically insignificant difference (p=0.115). There was a correlation between male gender and periodontitis (rho= -0.129, p=0.017).

Among different BMI groups, the highest occurrence of periodontitis was among obese participants (93.7%). Stage I periodontitis was the predominate stage, with 100% of underweight, 69.3% of normal, 63.7% of overweight adults and 73.4% of obese participants in this stage of the disease. A comparison of periodontitis occurrence between BMI subgroups revealed a statistically insignificant difference (p≥0.05). There was no correlation between BMI and periodontitis (rho=0.081, p=0.137).

Regarding SES and education levels, participants with a low SES and a low educational level had the highest occurrence of periodontitis (94.7% and 98%, respectively). In all SES and education level subgroups, most participants had stage I periodontitis (Table 3). A comparison of periodontitis between SES subgroups revealed a statistically insignificant difference (p ≥0.05) while there was a statistically significant difference (p =0.001) between education level subgroups. There was no correlation between periodontitis and education level (rho= -0.009, p=0.067), while an inverse correlation was found between periodontitis and SES (rho=-0.176, p =0.001).

In the present study, all adults who reported that they don’t brush their teeth had periodontitis (100%). The majority of participants in all brushing frequency subgroups suffered from stage I periodontitis (Table 3). A comparison of periodontitis occurrence between subgroups revealed a statistically significant difference (p=0.003). There was an inverse correlation between brushing frequency and periodontitis (rho= -0.234, p = <0.001).

A comparison of periodontitis incidence between consumption frequency subgroups for all dietary elements was statistically insignificant except for the consumption of other carbohydrates, eggs, grains, soda and citrus juices (p>0.05). The consumption frequencies of carbohydrates other than bread, grains, crackers and caffeinated drinks were shown to have a positive correlation with periodontitis (rho=0.142, p=0.008; rho=0.181, p=0.001; rho=0.111, p=0.04; and rho=0.114, p=0.034, respectively). Moreover, the consumption frequencies of sugar in drinks and candies were very close to a significant positive correlation with periodontitis (rho=0.105, p=0.053 and rho=0.105, p=0.052, respectively). For the consumption of all foods at all frequencies, the majority of participants suffered from stage I periodontitis (Table 3).

Underlying data

Figshare: Raw data for periodontitis 2.xlsx. https://doi.org/10.6084/m9.figshare.9756428.v1¹⁷

Extended data

Figshare: questionnaire periodontitis adult.docx. https://doi.org/10.6084/m9.figshare.9756542.v1¹³

Data are available under the terms of the Creative Commons Zero “No rights reserved“ data waiver (CC0 1.0 Public domain dedication).