Cephalometric appraisal of Class II treatment effects after functional and fixed appliances: a retrospective study

Three-dimensional analysis of the positional relationship between the dentition and basal bone region in patients with skeletal Class I and Class II malocclusion with mandibular retrusion

Objective

This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion.

Methods

Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python.

Results

In the Class II group, the mandibular anterior teeth inclined more labially (P < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females (P = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group (P < 0.05).

Conclusions

Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.

Volumetric measurements of mandibular incisor root resorption following Forsus FRD EZ2 and Bionator appliance treatment using cone-beam computed tomography: A preliminary study

Objectives:

Root resorption is one of the frequently encountered problems in orthodontic treatments. The effects of functional appliances on root resorption have not been clearly demonstrated. The aim of this study was to compare volumetric root resorption of mandibular incisors after Bionator and Forsus appliance treatment using cone-beam computed tomography (CBCT).

Materials and Methods:

The study sample (n = 30) was selected from Class II div. 1 mandibular retrognathia patients treated with the Bionator and Forsus appliances. The first CBCT scans were taken before Bionator use and after 6 months. In the Forsus group, the first CBCT scans were taken before Forsus appliance use and after an overcorrected Class I relationship was obtained. The mean treatment time with the Forsus appliance was 5 ± 1.2 months. Mimics software was used for segmentation and volumetric measurements of mandibular incisor teeth root resorption.

Results:

In the Bionator group, statistically significant root volume loss was not found. In the Forsus group, the differences between before and after the treatment were not statistically significant for teeth 41, 31, and 32 (P > 0.05), whereas the difference was statistically significant for the lower right second incisor (P < 0.002). The percentage of volume loss (%) and root volume loss (mm3) was not statistically significant between groups.

Conclusions:

Following functional treatment with the Bionator and Forsus, statistically significant difference was not found between groups for mandibular incisor root resorption.

Evaluation of growth changes induced by functional appliances in children with Class II malocclusion: Superimposition of lateral cephalograms on stable structures

Objective

To compare short- and long-term dentoalveolar, skeletal, and rotational changes evaluated by Björk’s structural method of superimposition between children with Class II malocclusion treated by functional appliances and untreated matched controls.

Methods

Seventy-nine prepubertal or pubertal children (mean age, 11.57 ± 1.40 years) with Class II malocclusion were included. Thirty-four children were treated using an activator with a high-pull headgear (Z-activator), while 28 were treated using an activator without a headgear (E-activator). Seventeen untreated children were included as controls. Lateral cephalograms were obtained before treatment (T1), after functional appliance treatment (T2), and after retention in the postpubertal phase (T3). Changes from T1 to T2 and T1 to T3 were compared between the treated groups and control group using multiple linear regression analysis.

Results

Relative to the findings in the control group at T2, the sagittal jaw relationship (subspinale-nasion-pogonion, p < 0.001), maxillary prognathism (sella-nasion-subspinale, p < 0.05), and condylar growth (p < 0.001) exhibited significant improvements in the Z- and E-activator groups, which also showed a significantly increased maxillary incisor retraction (p < 0.001) and decreased overjet (p < 0.001). Only the E-activator group exhibited significant backward rotation of the maxilla at T2 (p < 0.01). The improvements in the sagittal jaw relationship (p < 0.01) and dental relationship (p < 0.001) remained significant at T3. Condylar growth and jaw rotations were not significant at T3.

Conclusions

Functional appliance treatment in children with Class II malocclusion can significantly improve the sagittal jaw relationship and dental relationships in the long term.