Expansion and Extractions: Simple Solutions of Severe Crowding in the Mixed Dentition

by Quinzi Vincenzo

Background/Objectives Treatment of anterior crowding in the mixed dentition is frequently advocated due to its tendency to worsen in the permanent dentition and its association with negative self-perception. As treatment performed during growth might affect both skeletal and dental structures, the aim of the study was to compare the skeletal and dental effects of anterior crowding treatment by palatal expansion, serial extractions, or a combination of both in the mixed dentition phase. Methods Lateral cephalograms of 78 subjects (49 females and 29 males) aged 8.5±1.4 years successfully treated because of moderate to severe crowding of maxillary teeth were randomly selected. Based on the diagnosed etiology and treatment performed, subjects were allocated either to the sole expansion (EXP), serial extraction (EX), or expansion and extraction (EXP-EX) group until 26 records for each group were selected. Sagittal and vertical skeletal parameters and dental parameters were assessed, and between-group comparisons were performed at baseline and after the eruption of all permanent posterior teeth. Results All treatment modalities significantly affected the vertical skeletal parameters, mainly related to the occlusal plane and mandibular inclination, but no significant between or within-group differences were observed regarding maxillary inclination. A significant decrease of the mandibular inclination and increased facial height index was seen between baseline and follow-up in all groups. However, a significant decrease of the gonial angle was observed in the EXP group due to its decreased lower part, while in the EX and EXP-EX groups due to its decreased upper part. Upper incisor inclination significantly increased in the EXP group, while the interincisal angle increased only in the EX group. Conclusions Expansion, serial extractions, and a combination of both have similar skeletal, mainly vertical effects if performed in the mixed dentition. However, a different effect on the gonial angle was observed, with serial extractions leading to a decrease of its superior and expansion to its inferior part. Though, when considering early treatment of anterior crowding, the vertical effects of both maxillary expansion and serial extractions should be considered, and only limited dental effects are expected.

Learning Objectives

After this lecture, you will be able to define which cases of growing patients are to be treated with maxillary expansion, with serial extractions or both.
After this lecture, you will be able to evaluate the skeletal and dentoalveolar effects of the different therapies.
After this lecture, you will be able to recognize how in some cases the rotation of the occlusal plane has contributed to reduce verticality and improve the sagittal aspect.