The child's first dental visit. Age, reasons, oral health status and dental treatment needs among children in Southern Poland.

AIM: The aim of this study was to determine the age at and the reasons for the child's first dental visit, and to assess the oral health status and treatment needs in the analysed group of paediatric patients. MATERIALS AND METHODS: The study involved 320 children (154 girls and 166 boys) aged between 0.7 months and 13.5 years, visiting the dentist for the first time. All parents/legal guardians of the study participants gave written informed consent for participation in the study. Data on the child's age and reason for the dental visit were collected from interviews with parents. The state of oral health and dental treatment needs were assessed based on clinical examination, according to recommendations of the World Health Organization. STATISTICAL ANALYSIS: collected data were entered into an Excel spreadsheet and analysed using IBM SPSS software (version 24). Research hypotheses were verified using the Chi-square independence test at the level of statistical significance p<0.05. RESULTS: The mean age of children at their first dental visit was 3.79 years (+/- 1.82 years). The most common reasons (60%) for the first dental visit were pain followed by dental caries (33.1%) and the presence of decayed teeth (26.9%). The frequency of caries in the population was 75.9%, which means that only one out of four examined children was free from dental caries. Only 23.1% of patients did not require dental treatment and as many as 76.9% of the studied population needed dental treatment. CONCLUSION: Polish children make their first dental visit too late (usually at the age of 4 years) in relation to medical recommendations (between 6 and 12 months of life). The predominant reason for the child's first dental visit is caries and its complications. The results of this study indicate the bad oral health of Polish children making their first dental visit and low health awareness of parents and guardians.

Ultrafast all-optical temporal differentiators based on CMOS-compatible integrated-waveguide Bragg gratings.

We report the first realization of integrated, all-optical first- and higher-order photonic differentiators operating at terahertz (THz) processing speeds. This is accomplished in a Silicon-on-Insulator (SOI) CMOS-compatible platform using a simple integrated geometry based on (π-)phase-shifted Bragg gratings. Moreover, we achieve on-chip generation of sub-picosecond Hermite-Gaussian pulse waveforms, which are noteworthy for applications in next-generation optical telecommunications.

Second harmonic generation in AlGaAs photonic wires using low power continuous wave light.

We report modal phase matched (MPM) second harmonic generation (SHG) in high-index contrast AlGaAs sub-micron ridge waveguides, by way of sub-mW continuous wave powers at telecommunication wavelengths. We achieve an experimental normalized conversion efficiency of ~14%/W/cm2, obtained through a careful sub-wavelength design supporting both the phase matching requirement and a significant overlap efficiency. Furthermore, the weak anomalous dispersion, robust fabrication technology and possible geometrical and thermal tuning of the device functionality enable a fully integrated multi-functional chip for several critical areas in telecommunications, including wavelength (time) division multiplexing and quantum entanglement.

Magneto-optical control of light collapse in bulk Kerr media.

The Cotton-Mouton (Voigt) and Faraday effects induce adjustable linear and circular birefringence in optical media with external magnetic fields. We consider these effects as a technique for magneto-optical control of the transmission of bimodal light beams through Kerr-nonlinear crystals. Numerical analysis suggests that a properly applied magnetic field may accelerate, delay, or arrest the collapse of (2+1)D beams. Experimentally, the magnetic collapse acceleration is demonstrated in a bulk yttrium iron garnet (YIG) crystal.