**4. Discussion**

This study assessed the prevalence of dental caries and the health status of periodontal tissues among 200 migrants coming from developing countries and living in Northern Italy. To investigate the presence of dental caries we calculated the Decayed Missing Filled Teeth Index and decayed missing filled index for permanent and primary teeth, respectively. The DMFT/dmft represents the most important index used in epidemiological studies regarding the health status of the population, defining the number of decayed teeth, treated teeth, and the number of teeth missing due to carious lesions. It allows evaluation of the need for oral health interventions and strategies, to prevent dental decay [29,30]. The Community Periodontal Index of Treatment Needs was proposed in 1977 by the World Health Organization to measure periodontal disease and evaluate the treatment needs of populations [35–37].

Data obtained from the analysis reported, in general, a high prevalence of dental caries among the included patients, since more than half of them presented a DMFT/dmft ≥ 4, and only 10.5% had no decayed, filled, or missing teeth. Most of the selected sample was represented by children (age range 3–17 years old). Most of them were born in Italy but had both parents whose nation of birth is considered a middle- or low-income country.

In order to compare our data with a control population, we took into consideration the epidemiological study by Severino et al. [38]: this research evaluated the presence of Early Childhood Caries (ECC), by analysing the dmft index, in a paediatric Italian population

composed of 76 children and aged up to 6 years. In the same study, the educational level of the parents was collected by using a questionnaire, recording that more than 36% and 22% of mothers and fathers, respectively, had attended college (university). The authors of this article reported that more than half of the selected patients (59.21%) had never experienced caries, and that the majority of the parents used to brush their teeth 3 or more than 3 times a day.

The control group for children older than 6 years could be represented by the population sample selected in the study by Campus et al. [39], in which the DMFT/dmft Index and the CPI were calculated in 5342 Italian children aged 12 years. The national mean DMFT was equal to 1.09% (95% CI 0.98–1.21), and 23.8% of the patients had gingival bleeding, while 28.7% had calculus.

On the basis of the data collected from the literature [38,39], and according to the results of our observational study, it can be stated that the prevalence of dental caries appears to be higher in the migrant subjects living in Italy and coming from middle- and low-income countries than in the native population.

Our results are in line with the data recorded by Ferrazzano et al. [40]: the authors of this paper studied the DMFT index among migrant children with low incomes in South Italy, demonstrating higher levels of dental caries compared to the non-migrant population and showing a higher Unmet Restorative Treatment Needs index in migrant children than that of the native population.

van Meijeren-van Lunteren et al. [41] analysed the oral health-related quality of life (OHRQoL) in migrant children (coming from Morocco, Indonesia, Suriname, and Turkey) resident in the Netherlands. This research highlighted that the prevalence of caries-free dentition was higher among native children than among migrant participants and suggested that the low OHRQoL was mediated by the oral health status and the socioeconomic position.

According to the data obtained in our research, higher mean values of DMFT/dmft Index were recorded in patients coming from Bangladesh, China, Romania, the Philippines, El Salvador, Albania, and Ukraine. Subjects coming from Sri Lanka had the lowest mean DMFT/dmft values. No correlation could be found between the prevalence of dental caries and annual sugar consumption per person; according to the latest research, sugar intakes in China, the Philippines, and Albania were equal to 6.5 kg, 21.1 kg, and 16.5 kg per capita in 2019, respectively, while the annual sugar intake in Sri Lanka was recorded to be equal to 27.6 kg in 2019 [42].

The oral health of children is influenced by the oral hygiene habits of the family members [43], since family represents the primary socializing agent for children, who consequently imitate their parents in their oral hygiene practices [44].

The literature reported that, aside from cultural habits, the oral health status of migrant children could be associated with the family's socioeconomic condition, parental occupation, parents' education level, and marital status [45]. Parental knowledge on oral health and oral-health related behaviour are crucial for the prevention of dental caries in children, and these mediating factors vary based on cultural and ethnic backgrounds [46]. It was also demonstrated that the social context of migrant families from middle- and low-human development countries may be unfavourable for children's oral health [46].

With regard to the CPI, significant statistical differences were found after adjusting data for the educational level of the included participants (*p* value < 0.01), but the results regarding the DMFT/dmft Index were not significant at *p* value < 0.01. To support our data, a recent study conducted in the USA demonstrated the association between severe periodontitis among Whites and African Americans and a low income and low education level [47].

According to several studies, poor oral health in the migrant population may be associated with different factors: low socioeconomic status, unemployment, low education, ethnic background, language difficulties, and inequalities in access to oral healthcare facilities.
