A prospective clinical trial of the effects produced by the Connecticut intrusion arch on the maxillary dental arch

Abstract

Objective: To assess and compare the effects produced in the maxillary dental arch by means of Connecticut intrusion arch (CIA) with or without a cinch back on the distal end of the tube of the first molars.

Materials and methods: This study included 44 patients with a mean age of 13.1 ± 1.8 years treated for deep bite with a CIA randomly divided into two groups: group 1 (G1), 22 patients with initial mean age of 12.72 ± 1.74 years treated with the CIA in the upper arch without a cinch back on the distal surface of the tube of the first molars, and group 2 (G2), 22 patients with an initial mean age of 13.67 ± 2.03 years treated with the CIA with a cinch back. Lateral cephalograms were available before treatment (T1) and after intrusion of maxillary incisors (T2). The mean treatment period was 5.5 ± 1.45 months. Intragroup and intergroup changes in the maxillary incisor and molar positions were analyzed by paired and independent t-tests associated with the Holm-Bonferroni correction method for multiple comparisons (P < .05).

Results: There were significant differences between groups in terms of maxillary incisor displacement. The maxillary incisors flared labially (2.17°) and proclined (1.68 mm) in group 1, whereas a palatal inclination (-1.99°) and retroclination (-1.13 mm) was observed in group 2. No significant differences were found for the molar positions between the groups.

Conclusions: The presence or absence of a distal bend in CIA affects incisor tipping and proclination during intrusion mechanics.

Keywords: Biomechanics; Intrusion arch; Overbite.

Figure 1.

Consolidated Standards of Reporting Trials (CONSORT) flow diagram.

Figure 2.

Intrusion arch without a cinch back at the molar tube and the force system.

Figure 3.

Intrusion arch with a cinch back at the molar tube and the force system.

Figure 4.

Cephalometric diagram used for cephalogram measurements. The centroid (Cr) point was a constructed point 15 mm from the incisal edge along the long axis of the maxillary incisor. 1 = U1 angle to X: angulation of maxillary central incisor to X-axis; 2 = U1cr to X (linear distance of maxillary incisor centroid to x axis); 3 = U1 tip to U6D (linear distance of maxillary incisor tip to maxillary first molar distal aspect, perpendicular to x axis); 4 = U6 to X: angle of a line perpendicular to maxillary first molar mesial surface to x axis); 5 = U1 tip to X (linear distance between maxillary incisor tip to x axis perpendicularly); 6 = U6 apex to X (distance of maxillary first molar mesialbuccal root apex to x axis); 7 = U1 apex to X (distance of maxillary incisor apex to x axis); 8 = U1 apex to Y (distance of maxillary incisor apex to y axis); 9 = U1 tip to Y (distance of maxillary incisor edge to y axis). X indicates horizontal reference line passing from the ANS to the PNS; Y, vertical reference line perpendicular to the x axis passing through sella turcica. U1, maxillary central incisor; U1cr, centroid point of maxillary central incisor; U6, maxillary first molar; U6D, distal aspect of maxillary first molar.