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. 2021 Jun 29;17(1):23.
doi: 10.1186/s13005-021-00273-3.

Class II correction by maxillary en masse distalization using a completely customized lingual appliance and a novel mini-screw anchorage concept - preliminary results

Frauke Beyling  1 , Elisabeth Klang  2 , Eva Niehoff  2   3 , Rainer Schwestka-Polly  3 , Hans-Joachim Helms  4 , Dirk Wiechmann  2   3
Affiliations

Class II correction by maxillary en masse distalization using a completely customized lingual appliance and a novel mini-screw anchorage concept - preliminary results

Frauke Beyling et al. Head Face Med. .

Abstract

Background: The aim of the study was to evaluate the efficacy of a novel en masse distalization method in the maxillary arch in combination with a completely customized lingual appliance (CCLA; WIN, DW Lingual Systems, Germany). Therefore, we tested the null-hypothesis of a significant deviation from an Angle-Class I canine relationship and a normal overjet defined by an individual target set-up after dentoalveolar compensation in Angle Class II subjects.

Methods: This retrospective study included 23 patients, (m/f 3/20, mean age 29.6 years (min/max, 13.6/50.9 years)), with inclusion criteria of an Angle Class II occlusion of more than half a cusp prior to en masse distalization and treatment completed consecutively with a CCLA in combination with a mini-screw (MS) anchorage for uni- or bilateral maxillary distalization (12 bilateral situations, totalling 35). Plaster casts taken prior to (T0) and following CCLA treatment (T3) were compared with the treatment plan / set-up (TxP, with a Class I canine relationship and a normal overjet as the treatment objective). MSs were placed following levelling and aligning (T1) and removed at the end of en masse distalization at T2. Statistical analysis was carried out using Schuirmann's TOST [two one-sided tests] equivalence test, based on a one-sample t-test with α = 0.025 on each side (total α = 0.05).

Results: Ninety-seven percent of planned correction of the canine relationship was achieved (mean 3.6 of 3.7 mm) and also 97 % of the planned overjet correction (mean 3.1 of 3.2 mm), with a statistically significant equivalence (p < 0.0001) for canine relationship and overjet between the individual treatment plan (set-up) and the final outcome. Adverse effects were limited to the loss of n = 2 of 35 mini-screws. However, in each instance, the treatment was completed, as scheduled, without replacing them. Accordingly, the null-hypothesis was rejected.

Conclusions: The technique presented allows for a predictable correction of an Angle-Class II malocclusion via dentoalveolar compensation with maxillary en masse distalization.

Keywords: Anchorage; Class II correction; Distalization; Lingual appliances; Lingual orthodontics; Mini-screws; TADs.

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Conflict of interest statement

DW is the inventor of the WIN system. The WIN system is manufactured by DW Lingual Systems and DW is the CEO of this company. All other authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Completely customized lingual appliance (CCLA) combined with a novel mini-screw anchorage concept for maxillary en masse distalization. The 0.016’’ x 0.024’’ stainless steel archwire has an extra-torque of 13° from canine to canine and 2 cm expansion in the region of the first molars
Fig. 2
Fig. 2
Boxplot of canine relationship over the different time points (T0, T1, T2, T3) and treatment plan (TxP) defined by an individual set-up. Showing Median, interquartile range (IQR) and Min-Max
Fig. 3
Fig. 3
Boxplot of overjet over the different time points (T0, T1, T2, T3) and treatment plan defined by an individual set-up. Showing Median, Interquartile Range (IQR) and Min-Max
Fig. 4
Fig. 4
The initial class II malocclusion (a,b, T0) is worsening to more than half a unit during levelling and aligning (c,d). At the beginning of en masse distalization (T1), the lower curve of spee is levelled and the inclination of the upper incisors has improved (c,d). The buccal MSs are inserted with a 30 degree angle compared to the adjacent teeth. A few months later, the overjet is reduced and now the buccal screws have to be removed (e,f). Further bite correction achieved with the help of the palatal screws only, which now are removed (T2). Note the intrusion in the upper lateral segments (g,h). Final result (T3) after maxillary en masse distalization with upper torque control (i,j). A bilateral class I canine relationship and a normal overjet could be achieved
Fig. 5
Fig. 5
Superposition of the maxillary dentition at T1 and T2 on the palatal MSs (for illustrative purposes only, not used for measurements!). The distance between the two archwires in the anterior segment is indicating the amount of maxillary en masse distalization
See this image and copyright information in PMC

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