The removable quadhelix appliance

Impact of different cephalometric skeletal configurations on anatomic midface parameters in adults

OBJECTIVES

Skull morphology and growth patterns are essential for orthodontic treatment, impacting clinical decision making. We aimed to determine the association of different cephalometric skeletal configurations on midface parameters as measured in 3D CT datasets.

MATERIALS AND METHODS

After sample size calculation, a total of 240 fully dentulous patients between 20 and 79 years of age (mean age: 42 ± 15), who had received a CT of the skull within the scope of trauma diagnosis or intracranial bleeding, were retrospectively selected. On the basis of cephalometric analysis, using MPR reconstructions, patients were subdivided into three different vertical skull configurations (brachyfacial, mesofacial, dolichofacial) and the respective skeletal Class I, II, and III relationships. Anatomic parameters were measured using a three-dimensional post-processing console: the thickness of the maxillary and palatine bones as well as the alveolar crest, maxillary body and sutural length, width and height of the hard palate, maxillary facial wall thickness, and masseter muscle thickness and length.

RESULTS

Individuals with brachyfacial configurations had a significantly increased palatal and alveolar ridge thicknesses compared to those with dolichofacial- or mesofacial configurations. Brachyfacial configurations presented a significantly increased length and thickness of the masseter muscle (4.599 cm; 1.526 cm) than mesofacial (4.431 cm; 1.466 cm) and dolichofacial configurations (4.405 cm; 1.397 cm) (p < 0.001). Individuals with a skeletal Class III had a significantly shorter palatal length (5.313 cm) than those with Class I (5.406 cm) and Class II (5.404 cm) (p < 0.01). Sutural length was also significantly shorter in Class III (p < 0.05).

CONCLUSIONS

Skeletal configurations have an impact on parameters of the bony skull. Also, measurable adaptations of the muscular phenotype could result.

CLINICAL RELEVANCE

The association between viscerocranial morphology and midface anatomy might be beneficial for tailoring orthodontic appliances to individual anatomy and planning cortically anchored orthodontic appliances.

Development of a novel histological and histomorphometric evaluation protocol for a standardized description of the mid-palatal suture - An ex vivo study

The hard palate and mid-palatal suture are highly important for orthodontic treatment. In cases of transverse maxillary deficiency, palatal expansion is the treatment of choice. As nowadays a growing number of adult patients receive orthodontic treatment, an understanding of suture development throughout life is important to derive tailored orthodontic treatment techniques for each age group. Histological, histochemical and immunohistochemical stains (haematoxylin & eosin, Azan, Movat pentachrome, Masson-Goldner trichrome, Sirius Red, CD 31, osteopontin and TRAP) and histomorphometric analyses were re-established to detect the structural conditions of the mid-palatal suture in human cadavers of three different age groups (20-39, 40-59 and 60-80 years). The mid-palatal suture of the selected age groups (total of n = 12; n = 4 in every group m = f) exhibited marked differences in sutural morphology and metabolism. A wide, interdigitated and well-vascularized suture was observed in younger specimens compared with straighter and smaller sutures with fewer vessels and lower bone density in the 60-80 year group. The fibre composition within the sutural gap differed between the three age groups. Delicate fibres were found in the 20-39 year group, and a tightly interwoven 3D fibre-network was observed in the 40-59 year group. Atrophy primarily characterized the fibres in the 60-80 year group. This evidence demonstrates differences between the evaluated groups. These results suggest that the staining methods used are suitable for the description and evaluation of the morphology and metabolism of mid-palatal sutures. Further investigation is necessary to provide an in-depth description of sutural maturation over a lifetime.

A comparison of different treatment techniques for posterior crossbite in the mixed dentition

In this retrospective investigation, the changes occurring during the treatment of patients with posterior crossbite in the mixed dentition with the use of expansion plate and quad-helix appliances were evaluated and compared with those resulting from growth and development occurring in a control group of patients of similar age and type of malocclusion. The expansion plate group consisted of 13 patients, the quad-helix group of 14 patients, and the control group consisted of 10 children with transverse posterior crossbites in the mixed dentition. The research material was formed from orthodontic models and lateral and frontal cephalometric radiographs from 37 children. It was observed in this investigation that transverse expansion is achieved by both the expansion plate and quad-helix appliances. However, the average period of treatment was 1.2 years for the expansion plate, and 0.6 years for the quad-helix appliance. Although posterior crossbite was corrected in a fairly short period of time, the quad helix appliance caused considerable buccal tipping of the maxillary first permanent molars.

A simplified method of attachment for the quadhelix and transpalatal arch

A modification to the standard quadhelix transpalatal expansion arch is presented in which the wire passes distal to the most posterior molar and enters the mesial end of the headgear tube. Laboratory measurements were carried out on small, average and large sized appliances with this modification using a special rig fitted with strain gauges. For the three sizes of appliance, the modified quadhelix is more flexible than the standard quadhelix for both displacement and rotation of the molar arms. Also it is less time consuming to fit and remove it is concluded that this appliance is capable of producing clinically useful forces and couples with increased precision.

Methods of attachment for palatal arches: an evaluation

Orthodontic appliances attached to the palatal surfaces of molar bands are commonly used to produce, or is an aid to, active tooth movement. The present paper describes a number of the systems available for achieving this attachment and investigates their advantages and disadvantages in clinical practice.