BackgroundIn the long-lasting debate of extraction versus non-extraction treatment, the impact of extractions on the skeletal vertical dimension remains rather unclear. The aim of this retrospective research study was to obtain a bias-free sample of morphologically similar borderline patients treated with or without extraction of the four first premolars and to retrospectively evaluate the vertical changes that occurred.MethodsA borderline sample of 83 patients, 41 treated with four first premolar extractions and 42 treated without, was obtained by means of discriminant analysis applied to a previously investigated parent sample of 542 class I patients. The pretreatment and posttreatment cephalometric radiographs were analyzed digitally, and seven measurements were assessed for vertical skeletal changes. Also, average tracings between the two treatment groups were evaluated using the Procrustes superimposition method.ResultsThe variables of SN to Go-Gn and Y-axis showed adjusted intergroup differences of − 0.91° and − 1.11° (P = 0.04). Comparing the mean intra-group differences of all the variables simultaneously, a significant difference was found between the two treatment groups (overall P value = 0.04). In the extraction group, only the gonial angle showed a significant decrease (P = 0.01) while the overall P value evaluating the intra-group differences between pre- and posttreatment was significant (overall P value < 0.01). In the non-extraction group, the variable of N-ANS/N-Me showed a significant decrease (P = 0.02) and the overall P value evaluating the intra-group differences between pre- and posttreatment was also significant (overall P value < 0.01). Differences in treatment duration were assessed using a log-normal model and showed that extraction treatment lasted significantly longer than non-extraction treatment (P < 0.01).ConclusionsThe borderline group of patients identified by the discriminant analysis exhibited similar morphological characteristics at treatment’s onset; therefore, the posttreatment changes could safely be attributed to the choice of extraction or non-extraction treatment and not to pre-existing differences. Treatment choice had an impact on the patients’ vertical skeletal dimensions. Patients treated with four first premolar extractions showed a slight decrease in the vertical skeletal measurements, whereas non-extraction patient treatment showed a slight increase. The treatment time was also significantly higher in the extraction group.

Covariation patterns showed that the dental arches were integrated in width and depth. Integration in the vertical dimension was weak, mainly restricted to maxillary canine position.

The evidence indicates that borderline cases treated with four premolar extractions will exhibit lip retrusion compared to non-extraction treatment.

Summary Objectives To measure tooth movement 1 week post-treatment and assess potential correlation with changes invoked during treatment. Subjects and methods Thirty-eight patients were recruited (19 males, 19 females). Polyvinyl siloxane impressions were taken after bracket debonding (T1) and 1 week later (T2) and digitally scanned. During this period no retention was used. The digital casts were superimposed on structures of the hard palate. Translation and rotation of the first molars, canines, and central incisors were recorded. Additionally, movement of these teeth was assessed from the beginning (T0) until the end of treatment (T1). The correlation between the post-treatment relapse (T1–T2) and tooth movement during treatment (T0–T1) was investigated via the Spearman correlation coefficient. Results Relapse was detected and reflected changes in tooth position during treatment. For the first molars (right, left) the correlation between treatment and post-treatment tooth movement was evident in the transverse direction (r = −0.38, P = 0.020; r = −0.32, P = 0.052), tipping (r = −0.40, P = 0.015; r = −0.34, P = 0.034) and the antero-posterior direction (r = −0.31, P = 0.061; r = −0.36, P = 0.027); for the canines (right and left), as rotation around their long axis (r = −0.55, P = 0.003; r = −0.58, P = 0.002); for central incisors (right and left) in the antero-posterior direction (r = −0.55, P = 0.000; r = −0.48, P = 0.03), transverse direction (r = −0.43, P = 0.07; r = −0.32, P = 0.047), and rotation around their long axis (r = −0.53, P = 0.001; r = −0.28, P = 0.089). Conclusions Post-treatment changes in tooth position were mostly related to tooth movement during treatment. The reported correlations may help clinicians predict short-term relapse, evaluate long-term retention need, and design individualized retention schemes.

Dentin dysplasia is a rare hereditary disorder, transmitted by autosomal dominant mode, affecting both dentin and pulp. In Type I crown morphology is normal, but root dentin organization loss leads to shorter roots. Mutations in the SSUH2, VPS4B and SMOC2 genes have been reported as responsible for this condition. Orthodontic treatment was conducted on an 11-year-old female patient presenting the disorder along with bilaterally impacted permanent maxillary canines, in close proximity to the roots of the lateral and central incisors. Treatment plan included lateral incisors extraction, surgical exposure and traction of the impacted canines. Light forces were applied from a custom-made trans-palatal arch. Comprehensive orthodontic treatment was performed using edgewise appliances. After 3 years and 2 months, group function occlusion was achieved. The canines underwent composite resin restorations. At one year post-retention, the dentition remained stable. Family-based genetic analysis did not reveal any mutations in the aforementioned genes pointing to further genetic heterogeneity of this disorder. As dental medicine becomes more sophisticated and personalized, the association between mutation type/function and orthodontic treatment response may provide useful therapeutic insights. The positive treatment response of the presented case could be attributed to a more “benign” mutation awaiting to be identified.

No abstract