Evaluating the treatment effectiveness and efficiency of Carriere Distalizer: a cephalometric and study model comparison of Class II appliances

Abstract

Background: The purpose of this study was to evaluate the treatment effectiveness of Carriere Distalizer in comparison to Class II intermaxillary elastics and Forsus.

Methods: Three groups of patients treated with Class II intermaxillary elastics (n = 18), Carriere Distalizer (n = 18), and Forsus appliance (n = 18) were collected from three private orthodontic practices. Inclusion criteria were as follows: (1) 10-14 years old of start age with permanent dentition, (2) no history of previous orthodontic treatment, (3) complete pre- and post-treatment records, (4) dental Class II division 1 (end-to-end or more), (5) no pre-treatment transverse discrepancy, (6) non-extraction treatment plan, and (7) Class I post-treatment occlusal relationship. The data consisted of cephalometric and study model measurements from pre- and post-treatment records and treatment time. Two-tail Student t test was used to analyze the differences in cephalometric changes and dental corrections between Carriere Distalizer group and Class II elastics/Forsus group.

Results: All three groups of patients showed no differences in the age of treatment initiation, pre-treatment cephalometric measurements and discrepancy index (DI). The time of Class II correction for Carriere Distalizer was significantly shorter than that for Class II elastics; there was no difference in the length of Class II correction between Carriere Distalizer and Forsus groups. The amount of Class II correction (canine/molar relationship) was significantly lower for Carriere Distalizer when compared with Forsus appliance. Carriere Distalizer, similarly to Class II elastics, did not induce any statistically significant correction in skeletal component (ANB and Wits appraisal).

Conclusions: There is no clinically significant skeletal correction induced by Carriere Distalizer in growing patients. Carriere Distalizer can be applied to treatment of mild to moderate Class II dental malocclusion over 6 months on average, although the total treatment time may be prolonged due to various side effects. Overall, the Carriere Distalizer appears to be no more effective or efficient than alternatives in the treatment of Class II malocclusion.

Keywords: Carriere Distalizer; Class II elastics; Class II malocclusion; Forsus; Retrospective study.

Fig. 1

Carriere Distalizer and appliance used for the lower arch. Carriere Distalizer functions to distalize the posterior segment as a unit (A1 and B1). The lower arch, either banded with a lower lingual holding arch (A2) or held together with a clear retainer (B2), serves as the main anchorage source for Class II correction. Depending on the length of Carriere Distalizer, elastics can be worn from the upper canines or premolars to the lower molars

Fig. 2

Measurement of canine and molar relationship on digital study models. The reference surfaces for canine relationship were the interproximal contact point between mandibular canine and first premolar and the cusp of maxillary canine (A1 and B1); the reference surfaces for molar relationship measurement were the buccal groove of mandibular first molar and the mesiobuccal cusp of maxillary first molar (A2 and B2); The distances (millimeter) between the two reference surfaces of molar and canine were recorded separately for left and right sides in each subject

Fig. 3

a, b Length of treatment (total treatment time) and length of Class II correction (time for elastics/appliance use). *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 4

a, b Quantification of Class II correction based on measurements from pre- and post-treatment study models. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 5

a, b Pre- and post-treatment differences in ANB and Wits appraisal. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 6

a, b Pre- and post-treatment changes in SN-GoGn and FMA. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 7

a–f Pre- and post-treatment changes in maxillary and mandibular dental measurements. *P < 0.05, **P < 0.01, ***P < 0.001

Fig. 8

Potential side effects induced by Carriere Distalizer. A1, B1, C1, D1, and E1 pre-treatment intraoral photos. A2, B2, C2, D2, and E2 intraoral photos taken after 4 months of treatment with Carriere Distalizer. The intermaxillary elastics supported by Carriere Distalizer and lower lingual holding arch or clear retainer may result in extra space distal to maxillary lateral incisors (A2, C2, and D2), extrusion of maxillary canines (B2, C2, and D2), and worsening in arch length discrepancy in the mandibular arch (E2-lower right buccal segment)

Fig. 9

Relapse of derotated molar with Carriere Distalizer. A1 and B1 pre-treatment intraoral photos. A2 and B2 progress photos after 3 months of treatment with Carriere Distalizer. A3 and B3 progress photos 1 month after removal of Carriere Distalizer. The right molar relationship was corrected to Class I with Carriere Distalizer (B2) and part of the correction was achieved by derotating the upper right first molar (A2). However, there was a relapse of derotated upper right first molar after Carriere Distalizer was removed (B3)