Early childhood factors in the development of oral health behaviours in adolescence: A structural equation modelling approach

OBJECTIVES

Oral health behaviour is a learning process that begins in the early years of an individual's life. The aim of this study was to evaluate the associations between demographic, socioeconomic, and psychosocial factors and oral health behaviours during the transition period from childhood to adolescence.

METHODS

This was a cohort study with a follow-up of 7 years. The baseline assessment occurred in 2010 with a random sample of 639 preschool children from southern Brazil. Demographic, socioeconomic and psychosocial oral health conditions were assessed at baseline. Oral health habit variables were collected at follow-up and included questions regarding dental care and oral hygiene behaviours. Structural equation modelling was performed to assess the direct and indirect relationships between predictors at baseline in oral health behaviours at follow-up.

RESULTS

A total of 449 children were re-examined at follow-up (70.3% cohort retention rate). Factors directly related to poorer oral health behaviours (lower use of dental services, dental visits for emergency reasons and lower frequency of toothbrushing) were lower household income, lower maternal education, lower frequency of visits to neighbours or friends, and male sex. Considering indirect pathways, the household income and maternal education at baseline influenced oral health behaviours at follow-up via visits to neighbours or friends.

CONCLUSIONS

Our findings suggest that household income, maternal education and social capital play an important role in the development of oral health behaviours during the transition from childhood to adolescence. Acquisition of healthy oral behaviours is an important factor to consider in childhood. With this knowledge, public health policies can be developed to intervene in specific causal factors and improve oral health during this transitional period.

Percolation on Lieb lattices

We study site- and bond-percolation on a class of lattices referred to as Lieb lattices. In two dimensions the Lieb lattice (LL) is also known as the decorated square lattice, or as the CuO_{2} lattice; in three dimensions it can be generalized to a layered Lieb lattice or to a perovskite lattice. Emergent electronic phenomena, such as topological states and ferrimagnetism, have been predicted to occur in these systems, which may be realized in optical lattices as well as in solid state. Since the study of the interplay between quantum fluctuations and disorder in these systems requires the availability of accurate estimates of geometrical critical parameters, such as percolation thresholds and correlation length exponents, here we use Monte Carlo simulations to obtain these data for LLs when a site (or bond) is present with probability p. We have found that the thresholds satisfy a mean-field (Bethe lattice) trend, namely that the critical concentration, p_{c}, increases as the average coordination number decreases; our estimates for the correlation length exponent are in line with the expectation that there is no change in the universality class.

Charge Order in the Holstein Model on a Honeycomb Lattice

The effect of electron-electron interactions on Dirac fermions, and the possibility of an intervening spin-liquid phase between the semimetal and antiferromagnetic (AF) regimes, has been a focus of intense quantum simulation effort over the last five years. We use determinant quantum Monte Carlo simulations to study the Holstein model on a honeycomb lattice and explore the role of electron- phonon interactions on Dirac fermions. We show that they give rise to charge-density-wave (CDW) order and present evidence that this occurs only above a finite critical interaction strength. We evaluate the temperature for the transition into the CDW which, unlike the AF transition, can occur at finite values owing to the discrete nature of the broken symmetry.

Phonon Dispersion and the Competition between Pairing and Charge Order

The Holstein model describes the interaction between fermions and a collection of local (dispersionless) phonon modes. In the dilute limit, the phonon degrees of freedom dress the fermions, giving rise to polaron and bipolaron formation. At higher densities, the phonons mediate collective superconducting (SC) and charge-density wave (CDW) phases. Quantum Monte Carlo (QMC) simulations have considered both these limits but have not yet focused on the physics of more general phonon spectra. Here we report QMC studies of the role of phonon dispersion on SC and CDW order in such models. We quantify the effect of finite phonon bandwidth and curvature on the critical temperature T_{cdw} for CDW order and also uncover several novel features of diagonal long-range order in the phase diagram, including a competition between charge patterns at momenta q=(π,π) and q=(0,π) which lends insight into the relationship between Fermi surface nesting and the wave vector at which charge order occurs. We also demonstrate SC order at half filling in situations where a nonzero bandwidth sufficiently suppresses T_{cdw}.