Korean J Orthod.  2018 Jan;48(1):11-22. 10.4041/kjod.2018.48.1.11.

Predictors of favorable soft tissue profile outcomes following Class II Twin-block treatment

• Kim JE
• Mah SJ
• Kim TW
• Kim SJ
• Park KH
• Kang YG

• KMID: 2441437
• DOI: http://doi.org/10.4041/kjod.2018.48.1.11

Abstract

OBJECTIVE
The aim of this study was to determine cephalometric factors that help predict favorable soft-tissue profile outcomes following treatment with the Class II Twin-block appliance.
METHODS
Pre- and post-treatment lateral cephalograms of 45 patients treated with the Class II Twin-block appliance were retrospectively analyzed. Profile silhouettes were drawn from the cephalograms and evaluated by three orthodontists in order to determine the extent of improvement. Samples were divided into a favorable group (upper 30% of visual analogue scale [VAS] scores, n = 14) and an unfavorable group (lower 30% of VAS scores, n = 14). Skeletal and soft-tissue measurements were performed on the cephalograms and an intergroup comparison was conducted.
RESULTS
An independent t-test revealed that the following pre-treatment values were lower in the favorable group compared to the unfavorable group: lower incisor to mandibular plane angle, lower incisor to pogonion distance, point A-nasion-point B angle, sella-nasion line (SN) to maxillary plane angle, SN to mandibular plane angle, gonial angle, and symphysis inclination. The favorable group had a larger incisor inclination to occlusal plane. Moreover, the favorable group showed larger post-treatment changes in gonial angle, B point projection, and pogonion projection than did the unfavorable group.
CONCLUSIONS
Class II malocclusion patients with a low divergent skeletal pattern and reduced lower incisor protrusions are likely to show more improvement in soft-tissue profile outcomes following Class II Twin-block treatment.

Keyword

Class II Twin-block; Soft-tissue profile; Cephalometric predictors

MeSH Terms

Dental Occlusion
Humans
Incisor
Malocclusion
Orthodontists
Overbite
Retrospective Studies

Figure

• 

  Figure 1 The Class II Twin-block appliance used in this study.

• 

  Figure 2 An example of a pair of pre-treatment (left) and post-treatment (right) silhouettes used for evaluation by the panels.

• 

  Figure 3 Cephalometric analysis. A, Cephalometric landmarks (and the vertical reference plane) recorded: Nasion (N), sella point (S), condylion (Cd), articulare (Ar), basion (Ba), gonion (Go), anterior nasal spine (ANS), posterior nasal spine (PNS), point A (A), point B (B), pogonion (Pog), gnathion (Gn), menton (Me), upper incisor edge (UIE), upper incisor apex (UIA), lower incisor edge (LIE), lower incisor apex (LIA), infradentale (Id), upper molar mesial cusp tip (UM), lower molar mesial cusp tip (LM), glabella (Gb), soft-tissue nasion (sN), subnasale (Sn), labrale superius (Ls), labrale inferius (Li), soft-tissue pogonion (sPog), and the vertical reference plane perpendicular to the horizontal plane at 7° to the SN plane (VRP). B, Cranial base, facial height, and vertical measurements: (1) S-Ar, (2) S-N, (3) Ba-N, (4) N-S-Ar, (5) UAFH, (6) LAFH, (7) UPFH, (8) LPFH, (9), S-Ar-Go, and (10) maxillary plane angle (MxP)-mandibular plane angle (MnP). C, Anteroposterior mandibular dimension measurements: (1) SNA, (2) SNB, (3) VRP-Cd, (4) VRP-ANS, (5) VRP-A, (6) VRP-B, (7) VRP-Pog, (8) B-Pog, (9) S-N-Pog, (10), Cd-Go, (11) Cd-Gn, (12) Go-Gn, (13) Ar-Gn, (14) Ar-Go-Me, and (15) symphysis inclination. D, Dento-alveolar and soft-tissue measurements: (1) U1-MxP, (2) L1-MnP, (3) interincisal angle, (4) UM-MxP, (5) LM-MnP, (6) VRP-UM, (7) VRP-LM, (8) VRP-Gb, (9) VRP-sN, (10) VRP-Sn, (11) VRP-Ls, (12) VRP-Li, and (13) VRP-sPog. Terms and definitions are listed in Tables 1 and 2.

Reference

1. Cacciatore G, Alvetro L, Defraia E, Ghislanzoni LT, Franchi L. Active-treatment effects of the Forsus fatigue resistant device during comprehensive Class II correction in growing patients. Korean J Orthod. 2014; 44:136–142.

2. Han S, Choi YJ, Chung CJ, Kim JY, Kim KH. Long-term pharyngeal airway changes after bionator treatment in adolescents with skeletal Class II malocclusions. Korean J Orthod. 2014; 44:13–19.

3. Cozza P, Baccetti T, Franchi L, De Toffol L, McNamara JA Jr. Mandibular changes produced by functional appliances in Class II malocclusion: a systematic review. Am J Orthod Dentofacial Orthop. 2006; 129:599.e1–599.e12. discussion e1-6.

4. Davidenko N. Silhouetted face profiles: a new methodology for face perception research. J Vis. 2007; 7:6.

5. Singh GD, Clark WJ. Soft tissue changes in patients with Class II Division 1 malocclusions treated using Twin Block appliances: finite-element scaling analysis. Eur J Orthod. 2003; 25:225–230.

6. Baysal A, Uysal T. Soft tissue effects of Twin Block and Herbst appliances in patients with Class II division 1 mandibular retrognathy. Eur J Orthod. 2013; 35:71–81.

7. Baysal A, Uysal T. Dentoskeletal effects of Twin Block and Herbst appliances in patients with Class II division 1 mandibular retrognathy. Eur J Orthod. 2014; 36:164–172.

8. Quintão C, Helena I, Brunharo VP, Menezes RC, Almeida MA. Soft tissue facial profile changes following functional appliance therapy. Eur J Orthod. 2006; 28:35–41.

9. Vargervik K, Harvold EP. Response to activator treatment in Class II malocclusions. Am J Orthod. 1985; 88:242–251.

10. Barton S, Cook PA. Predicting functional appliance treatment outcome in Class II malocclusions--a review. Am J Orthod Dentofacial Orthop. 1997; 112:282–286.

11. Caldwell S, Cook P. Predicting the outcome of twin block functional appliance treatment: a prospective study. Eur J Orthod. 1999; 21:533–539.

12. Franchi L, Baccetti T. Prediction of individual mandibular changes induced by functional jaw orthopedics followed by fixed appliances in Class II patients. Angle Orthod. 2006; 76:950–954.

13. Toureno L, Kook YA, Bayome M, Park JH. The effect of western adaptation of Hispanic-Americans on their assessment of Korean facial profiles. Korean J Orthod. 2014; 44:28–35.

14. Patel HP, Moseley HC, Noar JH. Cephalometric determinants of successful functional appliance therapy. Angle Orthod. 2002; 72:410–417.

15. Björk A. Prediction of mandibular growth rotation. Am J Orthod. 1969; 55:585–599.

16. Tulley WJ. The scope and limitations of treatment with the activator. Am J Orthod. 1972; 61:562–577.

17. Pancherz H. The mandibular plane angle in activator treatment. Angle Orthod. 1979; 49:11–20.

18. Ahlgren J, Laurin C. Late results of activatortreatment: a cephalometric study. Br J Orthod. 1976; 3:181–187.

19. Parkhouse RC. A cephalometric appraisal of cases of Angle's Class II, Division I malocclusion treated by the Andresen appliance. Dent Pract Dent Rec. 1969; 19:425–433.

20. Sharma AA, Lee RT. Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 2. Soft tissue changes. Am J Orthod Dentofacial Orthop. 2005; 127:473–482.

21. Mills CM, McCulloch KJ. Treatment effects of the twin block appliance: a cephalometric study. Am J Orthod Dentofacial Orthop. 1998; 114:15–24.

22. Nelson C, Harkness M, Herbison P. Mandibular changes during functional appliance treatment. Am J Orthod Dentofacial Orthop. 1993; 104:153–161.

23. Sharma AK, Sachdev V, Singla A, Kirtaniya BC. Skeletal and dentoalveolar changes concurrent to use of Twin Block appliance in class II division I cases with a deficient mandible: a cephalometric study. J Indian Soc Pedod Prev Dent. 2012; 30:218–226.

24. O'Brien K, Wright J, Conboy F, Appelbe P, Davies L, Connolly I, et al. Early treatment for Class II Division 1 malocclusion with the Twin-block appliance: a multi-center, randomized, controlled trial. Am J Orthod Dentofacial Orthop. 2009; 135:573–579.