The ectopic eruption of the maxillary first permanent molar (EEM) is a local alteration of dental eruption with a multifactorial aetiology. The aims of our study were to determine the prevalence of the EEM in children and to analyse whether there is a relationship between EEM and dento-skeletal characteristics. A total of 322 children were analysed with the Ricketts cephalometric study and descriptive and analytical statistical analysis was carried out. The prevalence of EEM was 8.7%, with no statistically significant differences regarding gender or location, but a higher prevalence in the 7-year-old age group (18.8%) and bilateral EEM was more prevalent than unilateral EEM (p < 0.05). The most frequent findings were a shortened anterior cranial base, a retroposition of the maxilla and a distal position of the upper permanent first molar in relation to the pterygoid vertical in children with EEM. No statistically significant differences were found regarding the cephalometric parameters except a decreased palatal plane in the bilateral EEM group and a distal upper incisor position in the EEM group (p < 0.05). In conclusion, the prevalence of the EEM was 8.7%, more frequently bilateral, and significantly in seven-year-old patients. Children with bilateral EEM have decreased palatal plane values and a more posterior position of the upper incisor.

The aim of this manuscript analyses the efficacy of Transpalatal Arch (TPA) and Nance Button (NB) in maintaining space after the premature loss of upper primary molars. Study design: 54 subjects who needed space maintenance in the upper arch (23 in the TPA group and 31 in the NB group) and had radiographic follow-up until the appliance removal were enrolled in the study. The space loss was obtained from measurements carried out in initial and final radiographs. Type of dental loss and changes in molar relationship were also recorded. Results: The mean of space loss in the TPA group was 1.336mm, while in the NB group was 0.695mm, with no statistically significant differences between the total space loss neither the type of dental loss within the NB or TPA group (p &gt;0.05). Conclusions: The loss of space in the unilateral second primary molar is higher in the TPA group than in the NB group, with significant statistically differences (p&lt;0.05). It is concluded that the loss of the leeway space using a TPA as a space maintainer is greater than using a NB.

The aim of the present study was to analyse root resorption of the primary mandibular molars and their relationship with their permanent successors and the age of the patient. Methods: The sample consisted of 408 digital panoramic radiographs. The mesial and distal crown-to-root ratios (CRR) of #74 and #75 were calculated by dividing the measures of the length of each root by its coronal height. The Demirjian formation stage of the premolar was established, and dental age was determined. A descriptive and statistical analysis was performed using SPSS to determine the correlation between the variables (Pearson’s correlation coefficient) and to identify the differences between them (Student’s t-test), with a confidence level of 95%. Results: 723 molars were measured, and tables of CRR depending on dental and chronological age were obtained. The CRR decreased with increasing dental and chronological age, but not uniformly. The CRR of #74 and #75 decreased slightly when the successor premolar was in the initial stages of formation. Gender differences were obtained with respect to chronological age, mainly in girls, because the root resorption of #74 was always more advanced, and the formation of the #34 more advanced. Conclusions: Root resorption of the molar is slight and progressive when the successor premolar begins formation until stage D, and becomes higher starting at stage E. It is possible to determine the state of the child’s maturation and the CRR according to dental and chronological age.

Background: Dentinogenesis imperfecta type I (DGI-I) is a hereditary alteration of dentin associated with osteogenesis imperfecta (OI). Aim: To describe and study the morphological characteristics of DGI-I with scanning electron microscopy (SEM). Material and methods: Twenty-five teeth from 17 individuals diagnosed with OI and 30 control samples were studied with SEM at the level of the enamel, dentin–enamel junction (DEJ) and four levels of the dentin, studying its relationship with clinical–radiographic alterations. The variables were analysed using Fisher’s exact test, with a confidence level of 95% and asymptotic significance. Results: OI teeth showed alterations in the prismatic structure in 56%, interruption of the union in the enamel and dentin in 64% and alterations in the tubular structure in all of the cases. There is a relationship between the severity of OI and the morphological alteration of the dentin in the superficial (p = 0.019) and pulpar dentin (p 0.004) regions. Conclusions: Morphological alterations of the tooth structure are found in OI samples in the enamel, DEJ and dentin in all teeth regardless of the presence of clinical–radiographic alterations. Dentin structural anomalies and clinical dental alterations were observed more frequently in samples from subjects with a more severe phenotype of OI.