Soft tissue changes associated with Class III orthopaedic treatment in growing patients: a systematic review and meta-analysis

Abstract

Introduction: Achieving a harmonious soft tissue profile and enhancing facial appearance are key goals of early treatment for skeletal class III malocclusion.

Aim: To summarize the current evidence regarding the effects of Class III orthodontic treatment on facial soft tissues, and to compare various Class III orthodontic appliances.

Methods: A comprehensive search was conducted up to July 2024, using seven databases, with no language restrictions. RCTs and controlled non-randomized studies were included in this systematic review. The GRADE framework was applied to evaluate the quality of evidence.

Results: Thirty studies were included in this review, of which sixteen were appropriate for quantitative synthesis. The age range fell between 6.6 and 12.3 years. The FM/RME protocol resulted in a 1.58 mm increase in upper lip protrusion and a 4.73-degree decrease in the nasolabial angle compared to the control group. Chincup treatment led to a 2.13 mm increase in upper lip protrusion and a 2.63 mm decrease in lower lip protrusion compared to the control group. The pooled estimate demonstrated a significant increase of 1.82 mm in upper lip protrusion, a significant retrusion of 3.14 mm in the lower lip, and a backward movement of the chin by 4.8 mm in patients treated with miniplate-anchored orthopaedic facemask (FM/MP) compared to the untreated group. However, no significant difference was found between FM/RME and FM/MP, except for a noticeable decrease in the nasolabial angle in the FM/RME group. The analysis of FM/Alt-RAMEC versus FM/RME did not reveal any difference in soft tissue outcomes, except for the upper lip protrusion. The Alt-RAMEC group showed a more pronounced anterior movement of the upper lip by 0.67 mm compared to the RME group. The quality of evidence supporting these findings ranged from low to moderate.

Conclusions: There is low to moderate evidence suggesting that early treatment positively influences the soft tissues in Class III patients. However, these conclusions are based on a two-dimensional analysis of cephalometric images, which may not provide complete or accurate information. Therefore, more RCTs using comprehensive 3D analysis are needed to confirm these results.

Registration: PROSPERO ( CRD42024517924 ).

Keywords: Skeletal class III; Systematic review.

Fig. 1

PRISMA flow diagram of the included studies

Fig. 2

Summary of the risk of bias of randomized studies using ROB2 tool

Fig. 3

Summary of the risk of bias of non-randomized studies using ROBINS-I tool

Fig. 4

Forest plots of soft tissue changes associated with the FM/RME protocol compared to the control group: (A) Upper lip protrusion [SMD], (B) Upper lip protrusion [MD for studies assessed VR line], (C) Lower lip protrusion [SMD], (D) Lower lip protrusion [MD for studies assessed VR line], (E) Nasolabial angle

Fig. 5

Forest plots of soft tissue changes associated with the chincup compared to the control group: (A) Upper lip protrusion, (B) Lower lip protrusion

Fig. 6

Forest plots of soft tissue changes associated with FM/MP compared to the control group: A) Upper lip protrusion, B) Lower lip protrusion, C) Soft tissue pogonion (Pg’)

Fig. 7

Forest plots of soft tissue changes associated with the FM appliance compared to the control group: (A) lower lip protrusion, (B) Nasolabial angle

Fig. 8

Forest plots of soft tissue changes associated with FM/MP vs. FM/RME treatment: A) Upper lip protrusion, B) Lower lip protrusion, C) Nasolabial angle, D) Soft tissue pogonion (Pg’)

Fig. 9

Forest plots of soft tissue changes associated with Alt-RAMEC/FM vs. FM/RME treatment: A) Upper lip protrusion, B) Lower lip protrusion, C) Nasolabial angle, D) Soft tissue pogonion (Pg’)