1. Why is this study being done? After orthodontic treatment (such as braces), teeth can move back toward their original positions. To prevent this, orthodontists use retainers during the retention phase of treatment. One common option is a fixed retainer, which is a thin wire bonded to the inside surfaces of the front teeth. Fixed retainers help keep teeth in their corrected positions for many years. There are different types of fixed retainers, and they differ in how the wire is made. However, it is still unclear which type works best and lasts the longest. Some retainers may break, come loose, or make oral hygiene more difficult.

   This study aims to compare two commonly used types of fixed retainers to determine which one performs better over time.

2. What is the purpose of the study?

   The main goal of this study is to find out whether the type of fixed orthodontic retainer affects how long it remains intact and functional after orthodontic treatment. The study will also evaluate whether the type of retainer influences:

   - patient comfort and satisfaction

   - ease of maintaining oral hygiene

   • gum and periodontal health
   • stability of tooth alignment after treatment.

3. Who can participate?

   People may be eligible to participate if they:

   - are 15-50 years old

   - have completed orthodontic treatment

   • have all lower front teeth present
   • have healthy gums and teeth in the lower front area. Some patients will not be eligible if they have active gum disease or need additional dental treatment in the lower front teeth.

4. What will happen during the study? Participants who agree to take part will be randomly assigned to receive one of two types of fixed retainers. Random assignment means that a computer will decide which retainer each participant receives, similar to drawing lots.

The two types of retainers being compared are:

1. Round twisted wire retainer (3-strand stainless steel wire)

2. Braided rectangular wire retainer (8-strand braided wire) Both types are commonly used in orthodontic practice. 5) What will participants need to do? At the start of the study, the orthodontic appliance (braces) will be removed and the retainer will be bonded to the lower front teeth.

   Participants will attend follow-up visits over two years:

   • at the start of the study
   • after 3, 6,12, 18, and 24 months.

   During these visits, the research team will:

   - check whether the retainer is still intact

   - examine gum health

   • take dental impressions and photographs

   • ask participants to complete a short questionnaire about comfort and oral hygiene.

     6) What are the possible risks?

   The study procedures are the same as those commonly used in routine orthodontic care. Possible minor discomforts may include:

   - mild discomfort during gum examination

   - temporary discomfort when dental impressions are taken. No additional invasive procedures are planned. 7) Are there any benefits?

   Participants may benefit from:

   - regular monitoring of their retainer

   • routine evaluation of gum health

   • early detection of any problems with the retainer. The results of this study may help orthodontists choose the most reliable retainer for future patients.

     8) Is participation voluntary? Yes. Taking part in the study is completely voluntary. Participants may withdraw from the study at any time without affecting their orthodontic care. Personal information will be kept confidential and securely stored.

Orthodontic treatment is typically followed by a retention phase aimed at maintaining the alignment achieved during active treatment. Without adequate retention, teeth may gradually return toward their original positions, a phenomenon known as orthodontic relapse. Fixed retainers bonded to the lingual surfaces of the mandibular anterior teeth are widely used because they provide continuous stabilization without relying on patient compliance.

Several designs of multistranded stainless steel fixed retainers are available, differing in wire configuration, number of strands, cross-sectional shape, and mechanical properties. Despite their widespread use, there is limited clinical evidence comparing the long-term performance of different retainer designs. Existing reports indicate that failures of fixed retainers-such as wire fracture or detachment from the tooth surface-occur relatively frequently, particularly during the early months after placement. Failure rates of approximately 40-50% within two years have been reported for some retainer types, depending on materials and bonding protocols.

Traditional retainers made of twisted round multistranded stainless steel wire are commonly used in orthodontic practice. However, these retainers may occasionally unravel or deform, which can lead to unwanted tooth movement. Compressed braided retainers with a rectangular cross-section have been proposed as an alternative design that may offer improved mechanical stability and potentially reduce the risk of such complications. Comparative clinical data evaluating the performance of these two retainer types remain limited.

This study is designed as a prospective randomized controlled clinical trial with two parallel treatment groups. Participants completing orthodontic treatment and meeting eligibility criteria will be randomly assigned in a 1:1 ratio to receive either a three-stranded twisted round stainless steel retainer or an eight-stranded compressed braided rectangular retainer bonded to the mandibular anterior teeth. Randomization will be performed using a computer-generated sequence with permuted blocks to maintain balanced group sizes during recruitment. Allocation concealment will be ensured through the use of sequentially numbered, opaque, sealed envelopes opened after participant enrollment.

Blinding of clinicians and participants is not feasible because the structural characteristics of the retainers differ visibly. To minimize bias, standardized clinical procedures will be used for retainer placement and follow-up examinations, and predefined objective criteria will be applied to identify retainer failure events. Data analysis will be performed using coded group labels so that the statistician remains independent from the clinical procedures.

Participants will be monitored for a period of 24 months following retainer placement. During scheduled follow-up visits, the integrity of the retainer will be evaluated, and additional clinical examinations will be conducted to document oral health parameters and stability of tooth alignment. Patient-reported information will also be collected using structured questionnaires addressing comfort, satisfaction, and perceived oral hygiene difficulties associated with the retainers.

The results of this trial are expected to provide clinically relevant evidence regarding the comparative durability and clinical performance of two commonly used multistranded orthodontic retainers. Improved understanding of retainer survival and associated clinical outcomes may contribute to optimizing retention protocols and enhancing long-term stability following orthodontic treatment.

Inclusion Criteria:

• 15-50 years of age at debonding,
• all mandibular permanent incisors and canines present,
• no active caries, no restorations, no fractures on the mandibular incisors and canines,
• no periodontal disease;
• retention plan including only retainer bonded from 3 to 3

Exclusion Criteria:

• inadequate hygiene,
• need for restorative or surgical treatment,
• active periodontal disease,
• removable retainer as adjunct to a bonded retainer