Class II malocclusion treatment changes with the Jones jig, Distal jet and First Class appliances

Evaluation of Palatal Bone Thickness at the Implantation Areas of Two Popular Bone-Anchored Distalizers-A Cone Beam Computed Tomography Retrospective Study

Since class II malocclusion and lack of space within the dental arch due to early loss of deciduous molars is a common orthodontic problem in the Polish population, bone-anchored distalizers are becoming more and more popular. The aim of the present study was to evaluate palatal soft and hard tissue thickness using cone beam computed tomography (CBCT) at the area of micro-implant placement of two appliances for maxillary first molar distalization: Beneslider and TopJet distalizer. The study data were 100 consecutively selected CBCT images (53 of men and 47 of women). Measurements of bone and mucosa thickness were performed at six locations in the palate and tested according to their correlation with sex and age. The biggest bone and mucosa thickness were recorded in the insertion site of the TopJet miniscrew. Bone thickness in all points of paramedian insertion was significantly greater in males and the mean difference was approximately 1-1.8 mm. Age correlates significantly (p < 0.05) and positively (r > 0) with the thickness of the mucosa at all points: the older the patient, the thicker the mucosa at each measurement point. Anatomical diversity of the hard palate in the population involves the need to perform bone and mucosa thickness measurements before palatal micro-implant placement.

Effect of Molar Distalization on Condyle-Glenoid Fossa Relationship

Objective

It is essential to be aware of the potential effects of orthodontic treatment on tissues and anatomical structures associated with the masticatory system, especially the temporomandibular joint (TMJ). Little information is available about the consequences of molar distalization on the TMJ. Therefore, this study is aimed at investigating the changes of the condyle-fossa relationship after molar distalization using the distal jet appliance.

Materials and Methods

The sample consisted of twenty-five patients (mean age 20.4 ± 2.6) who underwent molar distalization by the distal jet appliance. CBCT scans were taken before (T0) and after (T1) the completion of the molar distalization. Joint spaces (anterior, superior, and posterior) and cephalometric vertical angles (SN.GOME and Björk sum) were measured and compared at T0 and T1.

Results

Superior and posterior joint spaces increased significantly after molar distalization (PS 0.29 mm, P < 0.001, SS 0.06 mm, P < 0.5). Vertical cephalometric angles also increased after molar distalization by the distal jet appliance (SN.GOME 0.92°, Björk 1.11°).

Conclusion

There was a statistically significant increase in the superior and posterior joint spaces after molar distalization. However, this increase may not be of clinical importance. The vertical dimension has also increased.

Dentoskeletal and soft-tissue changes of class II malocclusion treatment with modified first class appliances: a prospective clinical trial

Background/Objectives

Intraoral distalizers are effective and conservative alternatives for Class II malocclusion treatment. However, the literature is still controversial regarding the effects of using skeletal anchorage in intraoral distalizers with different designs. The aim of this study is to compare dentoskeletal and soft-tissue changes of Class II malocclusion patients treated with three types of First Class (FC) distalizers.

Materials/Methods

The sample of this prospective clinical trial included 30 consecutive patients divided into three groups: G1—FC conventionally anchored; G2—FC skeletally anchored Type 1; G3—FC skeletally anchored Type 2. Each group consisted of 10 patients. Lateral cephalograms were analyzed in two stages: at pre-treatment (T0) and after distalization (T1). The radiographs were digitized and analyzed using the software Dolphin Imaging 11.5. Comparisons of treatment changes between groups (T1–T0) were performed using one-way analysis of variance (ANOVA), followed by the Tukey test.

Results

Patients treated with the conventionally anchored FC showed significantly greater incisors protrusion and labial inclination, second premolars mesial inclination and mesialization than the FCs skeletally anchored. No differences were observed regarding the amount of molar distalization and molar angulation between groups.

Limitations

It can be considered that the limitation of this study lies in its non-randomized design.

Conclusions/Implications

First Class distalizers with conventional and skeletal anchorage are effective alternatives for Class II molar distalization. Distalization associated with indirect skeletal anchorage reduce the undesirable effects observed in the incisors and premolars during distalization when compared to distalization conventionally anchored.