Please select the arm or intervention descriptions that belong to the clinical trial below.
Title: Vacuum-formed Retainer Versus Bonded Retainer to Prevent Relapse After Orthodontic Treatment - A Randomized Controlled Trial About Stability and Patients' Perceptions
Brief Summary: The purpose of this trial is to evaluate and compare stability after orthodontic treatment with an Essix retainer and a bonded cuspid-to-cuspid retainer (CTC), respectively in the mandibular arch and longitudinally follow these patients over time up to 5 years. The patients' perceptions of the two methods are also evaluated with questionnaires during the follow-up period.

A further aim of this study is to analyze the relationship between diagnosis, treatment outcome, treatment time, age at start of treatment and stability with an Essix retainer in the maxilla.

The null hypotheses are:

* that there is no difference in retention capacity between Essix retainer and cuspid-to-cuspid retainer
* that there is no difference in patients' perception between Essix retainer and cuspid-to-cuspid retainer
* that there is no difference in retention capacity for Essix retainer in the maxilla concerning diagnosis before treatment, treatment outcomes, treatment time and age at start of treatment


Options:
A: Arm Label: Group A: CTC retainer + Essix retainer; Type: EXPERIMENTAL; Interventions: Device: CTC retainer, Device: Essix retainer maxilla, Procedure: Alginate impression, Other: Questionnaire | Arm Label: Group B: Essix retainer + Essix retainer; Type: ACTIVE_COMPARATOR; Interventions: Device: Essix retainer maxilla, Device: Essix retainer mandible, Procedure: Alginate impression, Other: Questionnaire | Intervention Type: DEVICE; Name: CTC retainer; Assigned to Arm(s): Group A: CTC retainer + Essix retainer | Intervention Type: DEVICE; Name: Essix retainer maxilla; Assigned to Arm(s): Group A: CTC retainer + Essix retainer, Group B: Essix retainer + Essix retainer | Intervention Type: DEVICE; Name: Essix retainer mandible; Assigned to Arm(s): Group B: Essix retainer + Essix retainer | Intervention Type: PROCEDURE; Name: Alginate impression; Assigned to Arm(s): Group A: CTC retainer + Essix retainer, Group B: Essix retainer + Essix retainer | Intervention Type: OTHER; Name: Questionnaire; Assigned to Arm(s): Group A: CTC retainer + Essix retainer, Group B: Essix retainer + Essix retainer
B: Arm Label: retainer: 0.75-mm-thick film; Type: EXPERIMENTAL; Interventions: Device: retainer | Arm Label: retainer: 1.00-mm-thick film; Type: EXPERIMENTAL; Interventions: Device: retainer | Intervention Type: DEVICE; Name: retainer; Assigned to Arm(s): retainer: 0.75-mm-thick film, retainer: 1.00-mm-thick film
C: Arm Label: Fiber-reinforced-composite retainer; Type: ACTIVE_COMPARATOR; Interventions: Device: Fiber-reinforced-composite retainer | Arm Label: composite-wire retainer; Type: ACTIVE_COMPARATOR; Interventions: Device: Composite-wire retainer | Intervention Type: DEVICE; Name: Fiber-reinforced-composite retainer; Assigned to Arm(s): Fiber-reinforced-composite retainer | Intervention Type: DEVICE; Name: Composite-wire retainer; Assigned to Arm(s): composite-wire retainer
D: Arm Label: Thermoplastic Retainer; Type: EXPERIMENTAL; Interventions: Other: orthodontic appliance | Arm Label: Hawley Retainer; Type: ACTIVE_COMPARATOR; Interventions: Other: orthodontic appliance | Intervention Type: OTHER; Name: orthodontic appliance; Assigned to Arm(s): Hawley Retainer, Thermoplastic Retainer

Answer: A