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The effect of third molars on maxillary molar distalisation using a miniscrew-supported 3D® maxillary bimetric distalising arch

Nilüfer İrem Tunçer
Nilüfer İrem Tunçer
 e 
Ayça Arman-Özçırpıcı
Ayça Arman-Özçırpıcı
   | 29 set 2022
Australasian Orthodontic Journal's Cover Image
INFORMAZIONI SU QUESTO ARTICOLO
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Pubblicato online: 29 set 2022
Pagine: 319 - 328
Ricevuto: 01 mag 2022
Accettato: 01 set 2022
DOI: https://doi.org/10.2478/aoj-2022-033
© 2022 Nilüfer İrem Tunçer et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

(A) Miniscrew insertion between first and second premolars (note proximity of the miniscrew to the second premolar root). (B) 3D® Maxillary Bimetric Distalizing Arch, 5-mm open Elgiloy coil-springs placed distal to the omega-loops, and molar bands with gingivally-placed headgear tubes (0.045-inch). (C) Activation of the open coil-springs with elastomeric chains. (D) Intraoral positioning of the 3D® Maxillary Bimetric Distalizing Arch from occlusal view.
(A) Miniscrew insertion between first and second premolars (note proximity of the miniscrew to the second premolar root). (B) 3D® Maxillary Bimetric Distalizing Arch, 5-mm open Elgiloy coil-springs placed distal to the omega-loops, and molar bands with gingivally-placed headgear tubes (0.045-inch). (C) Activation of the open coil-springs with elastomeric chains. (D) Intraoral positioning of the 3D® Maxillary Bimetric Distalizing Arch from occlusal view.

Figure 2.

Reference planes and cephalometric variables used in the study. Reference planes: SN (Sella–Nasion) plane; Occlusal plane, passing through mesiobuccal cusp tip of maxillary first molar and incisal edge of maxillary central incisor; GoGn (Gonion-Gnathion) plane; Horizontal reference plane (HRP), horizontal plane angulated 7° clockwise to the SN plane at Sella; Vertical reference plane (VRP), perpendicular plane to the HRP passing through Sella. Cephalometric variables: 1, SNA; 2, SNB; 3, ANB; 4, GoGn.SN; 5, Occ plane.SN; 6, Overjet; 7, Overbite; 8, U6root-VRP (perpendicular distance between mesiobuccal root apex of maxillary first molar and VRP); 9, U6trifurc.-VRP (perpendicular distance between trifurcation point of maxillary first molar roots and VRP); 10, U6M-VRP (perpendicular distance between mesial contact point of maxillary first molar crown and VRP); 11, U6 MB-HRP (perpendicular distance between mesiobuccal cusp tip of maxillary first molar and HRP); 12, U5.HRP; 13, U6.HRP; 14, U7.HRP; 15, U1i-VRP; 16, U1.HRP; 17, L1.HRP.
Reference planes and cephalometric variables used in the study. Reference planes: SN (Sella–Nasion) plane; Occlusal plane, passing through mesiobuccal cusp tip of maxillary first molar and incisal edge of maxillary central incisor; GoGn (Gonion-Gnathion) plane; Horizontal reference plane (HRP), horizontal plane angulated 7° clockwise to the SN plane at Sella; Vertical reference plane (VRP), perpendicular plane to the HRP passing through Sella. Cephalometric variables: 1, SNA; 2, SNB; 3, ANB; 4, GoGn.SN; 5, Occ plane.SN; 6, Overjet; 7, Overbite; 8, U6root-VRP (perpendicular distance between mesiobuccal root apex of maxillary first molar and VRP); 9, U6trifurc.-VRP (perpendicular distance between trifurcation point of maxillary first molar roots and VRP); 10, U6M-VRP (perpendicular distance between mesial contact point of maxillary first molar crown and VRP); 11, U6 MB-HRP (perpendicular distance between mesiobuccal cusp tip of maxillary first molar and HRP); 12, U5.HRP; 13, U6.HRP; 14, U7.HRP; 15, U1i-VRP; 16, U1.HRP; 17, L1.HRP.

Figure 3.

Reference planes and variables used in model analysis. Reference planes: Midpalatal raphe, the depression of the midpalatal suture; Rugae line, a perpendicular line to the midpalatal raphe passing through the same rugal points identifiable on both (T0&T1) dental casts. Dental cast variables: 1, U5-rugae line (distance between the central fossa of the second premolar and rugae line); 2, U6-rugae line (distance between the central fossa of the first molar and rugae line); 3, U7-rugae line (distance between the central fossa of the second molar and rugae line); 4, U5-U5 (inter-second premolar width); 5, U6-U6 (inter-first molar width); 6, U7-U7 (inter-second molar width); 7, U5.U5 (angle formed between the mesiodistal axes of the second premolars); 8, U6.U6 (angle formed between the mesiodistal axes of the first molars); 9, U7.U7 (angle formed between the mesiodistal axes of the second molars).
Reference planes and variables used in model analysis. Reference planes: Midpalatal raphe, the depression of the midpalatal suture; Rugae line, a perpendicular line to the midpalatal raphe passing through the same rugal points identifiable on both (T0&T1) dental casts. Dental cast variables: 1, U5-rugae line (distance between the central fossa of the second premolar and rugae line); 2, U6-rugae line (distance between the central fossa of the first molar and rugae line); 3, U7-rugae line (distance between the central fossa of the second molar and rugae line); 4, U5-U5 (inter-second premolar width); 5, U6-U6 (inter-first molar width); 6, U7-U7 (inter-second molar width); 7, U5.U5 (angle formed between the mesiodistal axes of the second premolars); 8, U6.U6 (angle formed between the mesiodistal axes of the first molars); 9, U7.U7 (angle formed between the mesiodistal axes of the second molars).

Figure 4.

Comparison of first molar movements between groups. Colored arrows represent the following; red, U6.HRP (amount and direction of tipping); purple, U6root-VRP (amount of root distalization at apex level); turquoise, U6trifurc.-VRP (amount of root distalization at trifurcation level); orange, U6M-VRP (amount of crown distalization at mesial contact point); blue, U6MB-HRP (amount of intrusion at mesiobuccal cusp tip).
Comparison of first molar movements between groups. Colored arrows represent the following; red, U6.HRP (amount and direction of tipping); purple, U6root-VRP (amount of root distalization at apex level); turquoise, U6trifurc.-VRP (amount of root distalization at trifurcation level); orange, U6M-VRP (amount of crown distalization at mesial contact point); blue, U6MB-HRP (amount of intrusion at mesiobuccal cusp tip).

Demographic characteristics of patients in the treatment groups.

Group 1 (Third molars extracted) (n= 11) Group 2 (Third molars present) (n= 12)
Mean (min-max) or n SD Mean (min-max) or n SD p
Age (years) 15.7 2.8 15.7 1.7 0.567
(13.4-21.2) (13.7-18.9)
Sex
    Female 9 10 0.876
    Male 2 2
Anteroposterior discrepancy
    1 / 4-cusp 0 0 0.789
    1 /2-cusp 6 7
    3/4-cusp 2 3
    full-cusp 3 2

Comparison of cephalometric and model measurements at the beginning of distalization (T0) and changes achieved with distalization (T1-T0).

Group 1 (Third molars extracted) Group 2 (Third molars present)
T0 Changes T0 Changes Between groups
Mean ± SD Mean ± SD p Mean ± SD Mean ± SD p Comparison at T0 p Comparison of changes p
Skeletal
    SNA (°) 80.7 ± 2.6 -1.1 ± 2.3 0.214 81.8 ± 2.9 -1.3 ± 2.8 0.292 0.391 0.066
    SNB (°) 74.9 ± 2.6 1.1 ± 1.5 0.396 75.8 ± 3.4 0.9 ± 1.5 0.721 0.369 0.437
    ANB (°) 5.8 ± 1.9 -0.5 ± 1.6 0.678 6 ± 3 0.9 ± 1.5 0.357 0.806 0.413
    GoGn . SN (°) 30.1 ± 4.1 -1.2 ± 1.5 0.678 33.3 ± 6.7 -0.8 ± 1.2 0.541 0.307 0.967
Dental - Model
    U5 - rugae line (mm) 6.1 ± 2.9 3.2 ± 2.1 0.008* 8.2 ± 2.7 3.6 ± 1.9 0.005* 0.142 0.514
    U6 - rugae line (mm) 15.3 ± 3 4.5 ± 1.8 0.008* 17.3 ± 2.6 3.9 ± 1.7 0.005* 0.102 0.191
    U7 - rugae line (mm) 25.7 ± 3.3 4.8 ± 1.9 0.008* 28.3 ± 2.5 3.6 ± 2.3 0.005* 0.041* 0.027*
    U5 - U5 (mm) 43.1 ± 3.6 1.8 ± 2.1 0.008* 43.9 ± 4.3 2.1 ± 3.9 0.005* 0.288 0.514
    U6 - U6 (mm) 41.8 ± 4.1 -0.2 ± 1.6 0.859 42.8 ± 2.7 0.6 ± 1.6 0.333 0.327 0.369
    U7 - U7 (mm) 47.2 ± 3.1 1.9 ± 3.7 0.008* 48.6 ± 3.6 7.2 ± 4.9 0.005* 0.369 0014*.
    U5 . U5 (°) 137.9 ± 11.4 10.5 ± 6 0.008* 135.8 ± 10.3 6.7 ± 6.9 0.032* 0.935 0.051
    U6 . U6 (°) 119 ± 9.3 -2.5 ± 7.5 0.314 121.9 ± 10 -2.7 ± 5.1 0.169 0.462 0.838
    U7 . U7 (°) 120 ± 6.4 3.7 ± 4.7 0.028* 119.6 ± 11.9 -6.2 ± 8.7 0.241 0.935 0.027*
Dental - Cephalometric
    U6M - VRP (mm) 41.2 ± 4.1 -3.9 ± 2.3 0.008* 39.3 ± 3 -3.4 ± 2.4 0. 007* 0.414 0.178
    U6trifurc. - VRP (mm) 37.6 ± 3.8 -4.5 ± 5.6 0.008* 36 ± 3.3 -3.5 ± 3.2 0.005* 0.514 0.022*
    U6root - VRP (mm) 40.3 ± 3.7 -5.5 ± 4.3 0.008* 38.7 ± 3.7 -3.8 ± 5.4 0.005* 0.624 0. 003*
    U5 . HRP (°) 96.2 ± 3.6 7.6 ± 3.7 0.008* 96.8 ± 4.8 8.6 ± 3.1 0. 005* 0.902 0.683
    U6 . HRP (°) 98 ± 3.5 -7.7 ± 3.2 0.008* 100.9 ± 3.6 -3.9 ± 2.7 0.005*0. 0.102 0.001*
    U7 . HRP (°) 108.4 ± 7.7 -4.1 ± 4.6 0.011* 113 ± 4.6 -1.1 ± 2.2 0.139 0.142 0. 027*
    U6 MB - HRP (mm) 64.2 ± 5.3 -1.9 ± 1.1 0.008* 59.9 ± 3.8 -1.1 ± 0.9 0.008* 0.079 0.005*
    Occ Plane . SN (°) 18.3 ± 5 4.9 ± 3.7 0.008* 16.9 ± 4.2 2.2 ± 3.2 0.007* 0.462 0.001*
    U1i - VRP (mm) 66.2 ± 7.8 -1.2 ± 1.6 0.008* 65.5 ± 4.6 -0.5 ± 2.7 0.038* 0.775 0.066
    U1 . HRP (°) 108.9 ± 11 -2.1 ± 2.8 0.028* 108.5 ± 8.2 -3 ± 2.2 0.005* 0.568 0.221
    L1 . HRP (°) 62.7 ± 5.8 0.9 ± 1.2 0.579 64.1 ± 4.3 0.7 ± 0.9 0.668 0.229 0.765
    Overjet (mm) 5.8 ± 2.8 -1.4 ± 1.9 0.261 5.2 ± 1.9 -1.1 ± 1.9 0.553 0.624 0.178
    Overbite (mm) 3.7 ± 1.7 -0.9 ± 1.2 0.859 3.2 ± 1.5 -1.5 ± 1.9 0.059 0.624 0.102
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