Background The frequency of traumatic dental injuries (TDI) in primary dentition and those agents that favor them present a great variability. Therefore, the objective of this study was to determine the prevalence of TDI in a population of Spanish preschoolers in temporary dentition and identify the factors associated with these injuries. Material and Methods An epidemiological observational prevalence study was carried out. A total of 343 children aged between 3 and 5 years were selected. A questionnaire was completed in relation to socioeconomic factors, cultural level, dietary habits and oral parafunction. Through an intraoral examination, information was collected on the occlusal characteristics and the presence of TDI. Data analysis was performed using the SPSS Statistics 25.0 program for Windows, using the descriptive and frequencies procedure, contingency tables, Chi-square test, and logistic regression analysis. Results The prevalence of TDI in the total sample was 12.2%. The most frequent lesion was crown discoloration (0.4%) followed by crown fracture (0.1%) and avulsion (0.1%). The most affected tooth was the deciduous upper central incisor. In the multivariate logistic regression analysis the presence of dental trauma did correlate significantly with the age (5 years in reference to 3 years: OR = 4.209; 95% C.I. = 1.591-11.134; p = 0.004) and overjet (OR = 2.609; 95% C.I. = 1.306-5.214; p = 0.007). Conclusions The prevalence of these lesions in a Spanish infant population with temporary dentition is low. Only age and overjet are risk factors. Key words: Dental trauma, deciduous dentition, risk factors.

The prevalence of bruxism in the preschool population varies according to different investigations. The aim of this study was to investigate the prevalence of sleep bruxism and its relationship with social and orofacial factors in children aged 3 to 5 years. Three hundred forty-three preschool children were divided into two groups, one with nocturnal bruxism, as reported by parents, and another without this disorder. Questionnaires were distributed to the parents to determine the children’s family social status and parafunctional habits at the time of the study. The clinical inspection confirmed the presence of certain parafunctional habits and the children’s occlusal characteristics. The data obtained were analysed using descriptive statistics such as frequency chi-square tests to identify the influence of qualitative variables. Of the total sample, 28.9% of preschoolers presented sleep bruxism. The highest prevalence was observed in boys (61.6%) at the age of 5 years (41.4%). Characteristics associated with this pathology were lip incompetence, open bite, crossbite, and overbite, with p < 0.05. Sleep bruxism in preschool children has a higher prevalence in boys and is more frequently expressed from 5 years of age. Open bite, overbite, and crossbite should be considered factors associated with parafunction.