Treatment effects of the Forsus Fatigue Resistant Device used with miniscrew anchorage

Abstract

Objective: To evaluate the dentofacial effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage (FRDMS) and compare them with those of conventional FRD and an untreated Class II control group.

Materials and methods: The sample consisted of 48 Class II subjects. Sixteen patients (13.68 ± 1.09 years of age) were treated with FRDMS, whereas 17 subjects (14.64 ± 1.56 years of age) were treated with only FRD. Also, a control sample of 15 untreated Class II subjects (14.13 ± 1.50 years of age) was constructed. Angular and linear measurements were made on 96 lateral cephalograms. Paired t, one-way analysis of variance, and Tukey tests were used for statistical analysis.

Results: Class I molar relationship and overjet correction were achieved in an average period of 6.5 ± 1.97 and 5.5 ± 1.80 months in the FRDMS and FRD groups, respectively. No skeletal effect was determined in both treatment groups. Greater overbite correction was found in the FRD group. Retrusion and extrusion of maxillary incisors, distalization of maxillary molars, and extrusion of mandibular molars were significant in both treatment groups. Labial tipping of mandibular incisors was significantly greater in the FRD group than in the FRDMS group.

Conclusion: Overjet and molar correction was totally dentoalveolar. Unfavorable labial tipping of mandibular incisors was effectively minimized with the usage of miniscrews.

Figure 1.

Spider screw inserted between the canine and first premolar root area.

Figure 2.

Forsus FRD used with miniscrews.

Figure 3.

Before and after lateral cephalograms and photos of a patient in the FRDMS group.

Figure 4.

Skeletal measurements on lateral cephalograms. VRL indicates vertical reference line, which is perpendicular to the HRL. HRL indicates horizontal reference line constructed by drawing a line having a 7° difference with the SN plane. 1: SN (mm); 2: SNA (°); 3: A-VRL (mm); 4: FH/NA (°); 5: SN/ANSPNS (°); 6: SNB (°); 7: B-VRL (mm); 8: Pog-VRL (mm); 9: Ar-Pog (mm); 10: FH/NPog (°); 11: ANB (°); 12: N-A-Pog (°); 13: N-Me (mm); 14: ANS-Me (mm); 15: S-Go (mm); 16: SN/GoGn (°); 17: Ar-Go-Me (°); 18: ANSPNS/GoMe (°).

Figure 5.

Dental and soft tissue measurements on lateral cephalograms. 1: SN/OP (°); 2: U1/L1 (°); 3: Overjet (mm); 4: Overbite (mm); 5: Lbsup-VRL (mm); 6: Lbinf-VRL (mm); 7: Pog'-VRL (mm); 8: Labiomental angle (°).

Figure 6.

Horizontal, vertical, and angular measurements of the maxillary and mandibular incisor and molars related to the reference lines. 1: U6-VRL (mm); 2: U6-HRL (mm); 3: U6/HRL (°); 4: U1-VRL (mm); 5: U1-HRL (mm); 6: U1/HRL (°); 7: L1-VRL (mm); 8: L1-GoMe (mm); 9: L1/GoMe (°); 10: L6-VRL (mm); 11: L6-GoMe (mm); 12: L6/GoMe (°); 13: Molar relationship (mm).