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Table 3 Calculation of the mean interval without severe complications that would require a separate appointment for repair: The number of study subjects was multiplied by average treatment duration and the resulting cumulative treatment time was divided by the number of actual severe complications. Severe complications equal, in the case of the WIN Herbst appliance investigated, the number of re-attachments of loose attachment shells, as there were no other severe complications. Equivalently, severe complications in comparison studies included e.g., crown/splint/trans-palatal arch-failure or –fractures, or telescope rod distortions. It should be borne in mind that the appliances compared here (and also compared in some of those studies) serve the same purpose, but are markedly different in design of their components

From: Clinical complications during treatment with a modified Herbst appliance in combination with a lingual appliance

  Vestibular appliance + Herbst Lingual appliance + Herbst
Appliance specifications Upper/lower cast-splint Upper/lower cast-splint (A) Upper steel crowns (1st molars), lower removable acrylic splint (B) Upper/Lower steel crowns (1st molars) (A) Upper steel crowns (1st molars), lower removable acrylic splint (B) Upper/Lower steel crowns (1st molars) Upper/lower fully customised Incognito Herbst/bracket system Upper/lower fully customised WIN Herbst/bracket system
Mode of appliance activation Not reported in detail Not reported in detail Not reported in detail Bite-jumping Step-wise Step-wise
Number of patients (n) 28 316 42 159 57 35
Frequency of severe complications (n) 94 755 77 219 159 8
Proportion of subjects with severe complications (%) 82.1 63.3 76.2 44.7 78.9 17.1
Duration of Herbst treatment (months) 6-7 7 12 12 12 6
Cumulative treatment time (months) 189 2.212 504 1.908 684 222
Mean interval without severe complications (months) 2.0 2.9 7.6 8.7 4.3 27.8
Reference Hägg et al. 2002 [12] Sanden et al. 2004 [14] Moro et al. 2011 [13] Silva et al. 2014 [16] O’Keefe 2013 [21] This study