One of the most crucial aspects of orthodontic therapy is retention, which is required to prevent orthodontic relapse . There are two main types of retainers, removable retainer which depends on patient compliance to achieve proper results, and fixed retainer which can overcome the problem of patient compliance, but with using it there is higher risk of plaque accumulation and the process of brushing teeth becomes more complex. However, it is not known whether this necessarily leads to worsening of periodontal outcomes . The increasing use of permanent retainers and their requirement for continuous wear highlight the importance of evaluating their impact on the periodontal health but there is conflicting data available right now on how orthodontic retainers affect periodontal diseases

The purpose of this research is to compare the effect between fixed and removable retainer on periodontium as the current evidence on how these appliances affect periodontal health is still lacking significantly Orthodontic treatment plays an important role in enhancing the function, esthetics and overall well-being of patients. One of the most important elements of treatment is the retention phase. There are two main types of retainers that can be used in the retention phase either fixed or removable.

At first banded fixed appliances were used as retainers , then in 1919 Hawly introduced removable retainers , then in 1973 Kneirim RW. introduced the first bonded retainer as enamel etching and modern adhesive systems facilitated the use of bonded retention .

The most widely used removable retainer is the Hawley appliance, which is made of wire and acrylic resin.

In 1971 Ponitz introduced fiber reinforced retainer which is less expensive, with better esthetics and easy to clean but it is not dimensionally stable and more prone to wearing.

The duration of the retention phase frequently exceeds that of the active treatment. In many cases, orthodontists even propose lifetime retention.

Removable retainers depend greatly on patient compliance so fixed compliance-free retainers were introduced but they cause more plaque accumulation and make the process of brushing teeth more complex, also there is conflicting data about their effect on periodontal health Artun was one of the first orthodontists to investigate the periodontal effect of fixed retainers. He found out that more plaque accumulation occurred with fixed retainers, but he suggested that plaque and calculus accumulation gingival to the retainer wire might not cause serious damage to the periodontium According to the most recent Cochrane review concerning this matter, most of the studies found no difference in periodontal measurements between the two types of retainers but one study found that the lower fixed retainer group had considerably more periodontal pocketing and bleeding on probing than the full-time lower removable retainer . Nevertheless, it is important to exercise caution when interpreting this periodontal pocketing outcome because the two groups were not similar at debonding, with four times as many participants in the fixed retainer group

The most recent systematic reviews also concluded that the available evidence on this topic is inconclusive and that more research is needed which would help in choosing the suitable type of retainer for each patient as there are no specific guidelines for choosing one type of retainer over the other for each patient. But they concluded that fixed retainers are compatible with periodontal health, or at least not related to severe detrimental effects on the periodontium.

It must also be taken in consideration several factors when interpreting the results of effect of fixed retainers on periodontal health like Hawthrone effect, limited follow up period and selection bias as most studies select people with good periodontal health .

The concept of periodontal health was derived from Chapple et al. and is basically defined as having no clinical loss of attachment, limited bleeding on probing (< 10%), and no significantly elevated probing depths (≤ 3 mm)

Inclusion Criteria:

• Minimal age of twelve years.
• Presence of all mandibular anterior teeth from canine to canine.
• Completion of orthodontic multi-bracket treatment with the requirement of retention of the mandibular anterior teeth.
• Periodontal screening index ≤ 2 [18].
• Participation in all study visits.

Exclusion Criteria:

• Systemic disease potentially affecting the study outcome.
• Conditions requiring antibiotic prophylaxis for clinical measurements that trigger transitory bacteremia.
• Pregnant females.
• Chronic use of medications affecting the study outcome.
• Patients with active periodontal disease