Dental development defects (DDDs) are quantitative and/or qualitative alterations produced during odontogenesis that affect both primary and permanent dentition. The etiology remains unknown, being associated with prenatal, perinatal, and postnatal factors. The aims were to identify the possible etiological factors, as well as the prevalence of DDDs in the primary and permanent dentition in a pediatric population. Two hundred twenty-one children between 2 and 15 years of age, patients of the master’s degree in Pediatric Dentistry of the Complutense University of Madrid, were reviewed. DDDs were observed in 60 children. Next, a cross-sectional, case-control study was carried out (60 children in the control group and 60 children in the case group). The parents or guardians completed a questionnaire aimed at identifying associated etiological factors. The prevalence of DDDs in patients attending our master’s program in both dentitions was 27.15%. Otitis, tonsillitis, high fevers, and medication intake stood out as the most relevant postnatal factors among cases and controls. The permanent maxillary right permanent central incisor and the primary mandibular right second molar were the most affected; there were no differences in relation to gender. One out of three children who presented DDDs in the primary dentition also presented DDDs in the permanent dentition. Prenatal and postnatal etiological factors showed a significant relationship with DDD alterations, considered risk factors for DDDs in both dentitions.

Based on the results of the 2015 oral health survey in Spain, the prevalence of untreated dental caries in temporary dentition, in the six-year cohort was 27,8%, and in the twelve-year cohort 14,6%. Due to the magnitude of the problem, the high health cost and the possibilities of prevention, monitoring the oral health status of the child population is extremely important, as it will allow the implementation of prevention and early care strategies. Objectives: To study the caries prevalence and malocclusion in the mixed dentition in children aged 6–12 years in Madrid, Spain. . Materials and methods: This is a descriptive, cross-sectional study carried out in the city of Madrid during the 2018–2019 school year. Fifth year students of the European University of Madrid through health surveys, calibrated and supervised by the two main researchers, collected the data. The schoolchildren assessed were students from different schools in the city of Madrid, between 6 and 12 years old. According to WHO standards, data were collected in 2 months. Results: The total number of students examined was 303 students from 4 different schools in the community of Madrid. The prevalence of caries in our sample in the primary dentition was 45.21% with dmf> 0 and in the permanent dentition it was 23.7 % with a DMF> of 0. Conclusions: The oral health survey carried out in the sample shows a high prevalence of caries, as well as in the dmf and DMF indicators. Most of the children needed fluoride applications, so it would be interesting to evaluate which of them can be prevented with different public health projects.

The hydrolysis of the collagen matrix by metalloproteinases (MMPs) is one of the paradigms that currently arouses most interest due to its close relationship with a decrease in bond strength (BS) and consequent restoration failure. Chlorhexidine 2% has demonstrated its ability to inhibit MMPs’ activity in the permanent dentition, improving the duration of resin–dentine, but there are few studies on deciduous dentition and its possible repercussions. Aim: To determine the influence of 2% chlorhexidine digluconate (CHX) as a dentine pretreatment on the BS of three adhesive systems on primary molars. Methods: 128 primary extracted molars were assigned to eight groups at random. BS in vitro was recorded by micropush-out test, and analyzed by two-way ANOVA. Results: BS values oscillated from 15.01 MPa to 20.41 MPa. There was no statistically relevant variation between the BS total mean of those adhesive groups that had received CHX pretreatment versus those that did not. Adper Prompt L-Pop was the self-etching adhesive with the best BS. Adper Scotchbond 1XT was the total-etch adhesive with the best BS values. Conclusions: Application of 2% chlorhexidine for 60 s as dentine pretreatment did not affect the immediate BS of several adhesive systems used in primary dentition.