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

Appliance specifications

Upper/lower cast-splint

Upper/lower cast-splint

(A) Upper steel crowns (1^st molars), lower removable acrylic splint (B) Upper/Lower steel crowns (1^st molars)

(A) Upper steel crowns (1^st molars), lower removable acrylic splint (B) Upper/Lower steel crowns (1^st 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