Methodology: After getting an informed written consent, each patient will be randomly allocated into two groups. After randomization, all patients will be treated according to a pre-set standard concept. Study models will be made for all subjects at the start (T0), 3months (T1), 6months (T2) and at the end of twelve months(T3) interval of retention phase. At each assessment, oral hygiene instructions will be reinforced. In case of fracture of the retainer, records will be made at that time interval. Retainer types and protocol: Retainer types: To examine the influence of different lingual retainer wires, each patient will be randomly divided into 2 groups for retainer wire placement in maxillary and mandibular arch. In the first group, 8 Braid Flat- Dead Soft Stainless Steel 6 inch retainer wire (Ortho-Direct, MO, USA) will be used as the lingual retainer; in the second group, 0.0195-in coaxial wire ( Ortho Organizers, Mount Holly, NJ) will be used. After making the impression, lingual retainers will be fabricated on plaster study models. The retainer wire will be prepared in tight contact with the lingual surfaces of incisors and canines. Silicon transfer keys will be used to transfer the retainer to the arch. The outcome measure in the study includes the following: 1. To assess the number of failures of two types of fixed retainers 2. To determine the time frame associated with the highest risk of debonding, 3. To investigate the post-treatment changes (failure of stability) after bonding of fixed retainers on the maxillary and mandibular arch. 4. Compare the effects of two retainers on the patient’s oral hygiene Follow-up and retainer failure: If any retainer failure occurred, the reason of failure (wire breakage/debonded) will be noted. The patients will be advised to come to the department without delay if they become aware of retainer failure. Otherwise, they’ll be recalled after the retainer was bonded, at 3months, 6months and at the end of 12 months interval of retention phase. When retainer failure occurred, it will be repaired with the same adhesives after removal of remnants. If a patient missed a follow-up session and visited the next month with an intact retainer, he/she will remain in the study. However, if the retainer fails during any period of absence lasting more than a month or he/she stopped attending the follow-up sessions, the patient will be excluded from the study. Little’s irregularity index will be used to measure the amount of crowding in the maxillary and mandibular arch. Previous studies have adapted the variables described by this irregularity index to evaluate maxillary arch crowding. A digital caliper will be positioned parallel to the occlusal plane. Each linear displacement between the 5 anatomic contact points of the anterior teeth will be measured. Little’s irregularity index involves measuring the linear displacement of the anatomic contact points of each mandibular incisor from the adjacent tooth anatomic point, the sum of these five displacements representing the relative degree of anterior irregularity Measurements will be obtained with a digital caliper. Each of the five measurements is obtained directly from the maxillary and mandibular cast rather than intraorally, since the proper positioning of the caliper is essential for consistent accuracy. The mandibular cast is viewed from above, sighting down onto the incisal edges of the anterior teeth, the caliper held parallel to the occlusal plane while the beaks are lined up with the contact points to be measured. Pretreatment cast will be subjectively ranked on a scale ranging from 0 to 10, using the following criteria: 0 Perfect alignment l-3 Minimal irregularity 4-6 Moderate irregularity 7-9 Severe irregularity 10 Very severe irregularity All the measurements will be made at the following time points: T0: start of retention phase T1: 3months of the retention phase T2: 6 months of the retention phase T3: 12 months of the retention phase Clinical assessment of the periodontal health status will be done by measuring plaque index (PI) , gingival index (GI), calculus index (CI) and papillary bleeding index (PBI). 1. Plaque index (PI), as described by Loe, was evaluated using a disclosing agent on the lingual surfaces of all maxillary and mandibular anterior teeth. Plaque accumulation will be categorized using the following scale: 0 -Absence of plaque deposits 1 -Plaque disclosed after running the periodontal probe along the gingival margin. 2 -Visible plaque 3 -Abundant plaque The results will be averaged for the six maxillary and mandibular teeth, and a mean value will be recorded. 2.Calculus index (CI) using the following scale: 0 -Absence of calculus 1 -Presence of calculus covering up to one-third of the tooth surface 2 -Presence of calculus covering up to two-third of the tooth surface and/or the presence of separate flecks of subgingival calculus 3 -Presence of calculus covering more than two third of the tooth surface and/or presence of a continuous band of subgingival calculus The results will be averaged for the six maxillary and mandibular teeth, and a mean value will be recorded. 3. Gingival index (GI) suggested by Loe, includes the following:0 -Absence of inflammation 1 -Mild inflammation, a slight change in color, little change in texture, no bleeding on probing 2 -Moderate inflammation, moderate glazing, redness, edema and hypertrophy, bleeding on probing 3 -Severe inflammation, marked redness, hypertrophy, the tendency for spontaneous bleeding, ulceration GI will only be assessed on the lingual surfaces so that the presence of any labial inflammation does not affect the results. 4.Papillary bleeding index (PBI): will be measured 15sec after the insertion of the periodontal probe into the gingival sulcus. 0- No bleeding 1- Singular bleeding point 2- Several bleeding points or a thin bleeding line along the marginal gingiva 3- Bleeding in the entire interdental gingival triangle immediately after probing 4- Profuse bleeding during probing, bleeding extending over the marginal gingiva eventually with the development of blood drops Patient satisfaction will be assessed by asking the patient three set of questions regarding the retainer, to which they need to answer in yes/no. 1. Any food lodgement? 2. Any difficulty in brushing? 3. Any irritation to tongue? All the measurements will be made at the following time points: T0 : start of retention phase T1: 3months of the retention phase T2: 6 months of the retention phase T3: 12months of the retention phase Successful treatment will be defined as lack of any failure, ranging from a single-tooth debond to a total retainer breakage over a period of 12months, perfect alignment of incisors and canines, absence of plaque and calculus deposits, absence of inflammation and no bleeding on probing of maxillary and mandibular incisors over a period of 12 months. Data Analysis Plan: Assuming a proportion of 0.13 and 0.19 in two groups with risk difference of 0.06, and absolute precision of 80% with clinically significance level of 0.05, a sample size of 26 patients per group has been calculated. With a dropout rate of about 20%, 32 patients will be required to be included in each group. SPSS software (Version 20.0) will be used for statistical analysis of the data. For numerical variables, arithmetic means and standard deviation will be calculated. Analysis of means will be made with independent sample t-test to compare active treatment duration and treatment effects between the groups. A P value of less than 5 percent (P=0.05) will be regarded as statistically significant.
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