Studying risk indicators of periodontitis provides dental clinicians with insight into the causative and possible contributing factors of this unique and complex disease in their society. This would improve diagnosis, treatment planning, treatment, prevention and referral of AgP cases.
Socio-demographic factors
Age
The majority of AgP patients were young, which is in agreement with the tendency of AgP to start early in life [13]. Albandar et al. [14] reported that the prevalence of EOP in Ugandan school attendees aged 12-25 years was high (28.8%). The 1999 AAP classification has minimized the value of age in the diagnosis of AgP, although still stating that AgP affects young individuals [7]. Interestingly, the multivariate analysis showed that the odds of having AgP in subjects older than 35 yrs. was 10 times higher than in those under 35 yrs. This result was probably obtained due to two factors: first; the control subjects were younger than AgP subjects, simply meaning that they were young and didn’t have periodontitis. Second; the diagnosis of periodontitis was based on CAL values, so that this “higher odds of having AgP with increasing age” probably reflects the cumulative effect of AgP (manifested as greater attachment loss) that had affected these patients at a younger age, and progressed with increasing age. This finding is supported by the results of other studies [8, 15]. Such as the study of Albandar et al. [8] who estimated the prevalence of aggressive periodontitis in US schoolchildren to be 0.4% among 13- to 15-year old children and 0.8% among the 16- to 19-year-old group. Another study investigated 13-year-old Brazilian children at baseline and 3 years later and found a higher percentage of AgP in the older age group [7, 16].
Gender
More than one half (57%) of the participants in this study were females. Females represented most of the AgP group, as opposed to controls, where the number of males was higher. The multivariate logistic regression analysis revealed that females were about four times more likely to have AgP, in agreement with some studies on Caucasians [8, 17].
A recent comprehensive review of the literature on the prevalence and demographics of AgP by Susin et al. [15] showed that there is a complex relationship between the prevalence of AgP, gender, and certain demographic variables, such as race/ethnicity. This review showed that in most populations the prevalence of aggressive periodontitis is similar in male and female subjects. A survey involving 17-26 yrs. old American recruits [18], found that the prevalence of juvenile periodontitis was similar in males and females. However, they observed a significantly higher prevalence of juvenile periodontitis in males than in females when only black recruits were studied, indicating that gender distribution of AgP differs between ethnic groups [18]. This study reported the following female: male ratios of disease prevalence: 0.52:1 in Black people; 4.3:1 in Caucasians; and 3:1 in other races.
Education and residency
The majority of AgP patients had received ≤12 years of education (equal to or less than high school). Previous studies have reported that education and place of residence are important factors in periodontal health but education has a greater influence on the level of periodontitis [19, 20]. Most AgP patients in our study reported living in urban areas, which may indicate that AgP patients living in the city seek periodontal treatment more frequently than rural area dwellers. Rural areas often have poorer socioeconomic conditions and medical facilities than urban areas.
Oral hygiene habits, dental visits and periodontal parameters
Dental plaque is the principal etiologic factor of periodontitis as demonstrated by the early studies of Löe and co-workers [21]. In the present study, most AgP patients reported brushing their teeth rather regularly (≥ 1 time/day). But in spite of that, most of them had dental plaque and gingival inflammation. This may either indicate that the tooth brushing methods used by patients were incorrect or that their reports were inaccurate. Controls reported adequate brushing frequency, proper tooth brushing methods and demonstrated better periodontal conditions than AgP patients. This is probably because most of the control subjects were young educated individuals who took care of their oral health. Axelsson et al. [22] reported that intensive oral hygiene programs were effective in reducing the incidence of dental caries and the level of gingival inflammation in children and adults. As for the frequency of dental visits, AgP patients visited the dentist more frequently than controls, possibly due to their need for continuous periodontal treatment and/or replacement of missing teeth.
With regard to the presence of local etiologic factors, although the oral hygiene habits reported by the AgP and control groups were comparable, the AgP patients demonstrated higher plaque scores and attachment loss. AgP has been associated in the literature with minimal amounts of plaque [13], which is in contrast with findings in our AgP population, who demonstrated more plaque than controls. This is probably related to differences between populations in oral hygiene standard and dental awareness. The attachment loss observed in the AgP group probably reflects periodontal response to dental plaque and the high susceptibility of AgP patients to periodontal breakdown. Classically, AgP has been associated with small amounts of local factors [7]. Periodontal destruction in AgP is initiated by the interaction between pathogenic microorganisms and the host immune system [23, 24], with a pronounced role of the host immune reactions (reviewed by Albandar, 2014) [7].
Smoking
Evidence suggests a very strong association between smoking and gingival tissue status, periodontal tissue loss and severity of periodontitis [3, 25]. In the present study, the percentage of smokers was 16.7% of the whole study population. The majority of subjects in the AgP group denied smoking. This indicates that AgP patients were not heavily exposed to smoking; nevertheless, they had greater periodontal destruction, which supports the high susceptibility of AgP patients to periodontal breakdown. The reason why the percentage of AgP smoker patients was not high may be that some AgP patients could have become aware of the risks of smoking during their visits to dental professionals. Alternatively, this may be due to the fact that the majority of AgP patients were young females who usually deny smoking in the Jordanian society, as it is considered inappropriate for females to smoke.
Although smoking is a well-known and universally accepted risk factor for the initiation, progression and severity of periodontitis [26], the results of the multivariate analysis in this study did not reveal any association between smoking cigarettes, cigarette numbers or duration of smoking and periodontal status. This disagreement may be due to variations among studied populations, sample number and, mostly, accuracy and subjectivity of self-reporting by patients.
Family history and parents’ consanguinity
It is well recognized that AgP aggregates in families [7, 15, 27]. A currently widely held view is that the destruction observed in periodontal disease is the result of an improperly regulated immune response to bacterial infection rather than the directly destructive effect of the bacterial pathogens themselves [28]. Specific genotypes, such as polymorphisms in IL-1 [29, 30] genes have been linked to increased risk of periodontal diseases [31].
In the present study, more than half of AgP patients reported periodontal problems among other family members, and by that, significantly differed from controls, in agreement with other studies [32]. Familial aggregation of periodontitis may result from shared genes, shared environmental exposures and similar socioeconomic influences. Marriage between relatives, particularly cousins, as a social habit in the Jordanian society was not found to be a risk indicator of AgP in the current study. This is in agreement with previous results [33, 34], but additional studies are recommended to investigate this factor. Marriage between relatives can be looked at as “inbreeding”, the impact of which is well documented on Mendelian disorders. However, very little is known on the effects of inbreeding on late onset and complex, multifactorial diseases such as periodontitis. A study conducted on an Israeli-Arab community reported that in spite of the high rate of consanguinity, no significant difference was found in the prevalence of complex diseases like diabetes, myocardial infarction and asthma between the offspring of consanguineous versus non-consanguineous parents [34].