Second Class Functional Treatment: Andreasen Activator vs Twin Block

The purpose of this research is to analyze and compare the dental and skeletal changes induced by two functional devices, Andreasen Activator and Clark's twin block, on the sagittal and vertical plane, by means of cephalometric analysis, of the lateral cephalograms prescribed at the beginning and at the end of the treatment for a second skeletal class, first division with normal or deep bite.

Twenty patients, 8 females and 12 males, fulfilling criteria for inclusion, were divided randomly into two groups: group I was treated with Andreasen activator, the second group with Clark's twin block. The duration of the therapy was about 18 months plus less 2 months. Pretreatment and posttreatment cephalometric radiographs were analyzed using angular (SNA, SNB, ANB, SnaSnp-GoGn angles), linear (Sna-Snp, Co-Gn, Co-Go, Go-Gn) skeletal parameters and dental one (U1-SnaSnp angle, L1-GoGn angle, Overjet and Overbite). To evaluate the posttreatment changes in the single groups and between them, paired and unpaired t-test was used.

In both of the two groups analyzed, all the sagittal and vertical, angular and linear, skeletal measurements appear to be increased in a statistically significant way, except SNA angle and the distance Sna-Snp. Regarding the dental parameters, in the group treated with Andreasen activator, only Overjet and Overbite showed statistically significant differences. On the other hand, twin block induced statistical changes about Overjet, Overbite and also U1/SnaSnp, but not about L1/GoGn. The advancement of the mandible determines a greater prominence of the chin and lower lip, an increment of the labial mental angle and a reduction of the convexity of the profile. Also, the decrease of the overjet and, consequently, of the dental exposure improve the esthetic appearance of the patient's face.

Both functional treatments showed a lower jaw advanced on the sagittal plane and increased in size. In the upper jaw no significant changes were observed. It was also evident a dental compensation both on sagittal and vertical planes.

The functional devices studied, Andreasen activator and twin block, seem to obtain more skeletal than dental results when the patients were treated at the peak of pubertal growth.

Baccaglione G, Rota E, Ferrari M, et al. Second Class Functional Treatment: Andreasen Activator vs Twin Block. Int J Clin Pediatr Dent 2020;13(2):144-149.