The purpose of the study was to compare the clinical effectiveness of bonded versus vacuum-formed retainers regarding their retention capacity; periodontal health; survival rates; and patients' perception after 12 months of removal of fixed appliances. The null hypotheses considered that there was no differences between the retainers in relation to the aspects evaluated.
This single-center randomized controlled trial was performed at the Department of Orthodontics, Bauru Dental School, University of São Paulo, Brazil. A total of 50 patients completing orthodontic treatment were recruited. The patients were prospectively and randomly allocated into two groups. The first group consisted of 25 patients with canine-to-canine V-bend bonded retainers; while the second group comprised 25 patients with vacuum-formed retainers. In both groups, the same retainers were installed in the maxillary and mandibular arches. Patients were evaluated at deboning (T0), after 3 months (T1), 6 months (T2), and 12 months (T3). In each appointment, digital models were obtained and the other clinical variables were evaluated. The primary and secondary outcomes were compared between retainers in the time-points evaluated.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
50
Traditional stainless steel retainer commonly bonded in the anterior teeth of the mandibular arch to maintain their alignment after orthodontic treatment.
Removable retainers made of plastic and derivatives. Currently gaining popularity due to the increased use of esthetic aligners. These clear retainers have the objective to maintain stable the results obtained after orthodontic treatment. They cover all the surfaces of the teeth up to the first or second molars.
Bauru Dental School, University of São Paulo
Bauru, São Paulo, Brazil
Changes in Little Irregularity Index (LII)
Stability was evaluated comparing the changes in the Little Irregularity Index (LII) between time-points. The average of the linear distances between the anatomical contact points of the anterior teeth were considered.
Time frame: Changes were compared at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Intercanine Distance
Distance between the cusp tips of the right and left permanent canines. In the maxilla and mandible.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Intermolar Distance
Distance between the tips of the mesiobuccal cusps of the first right and left permanent molars. In the maxilla and mandible.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Overjet
Distance between the incisal edge of the maxillary central incisor and the incisal edge of the mandibular incisor, parallel to the occlusal plane.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Overbite
Distance between the incisal edge of the upper central incisor and the incisal edge of the lower incisor, perpendicular to the occlusal plane.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Calculus Accumulation
Periodontal status was evaluated regarding the amount of calculus accumulation using the Simplified Oral Hygiene Index from Greene and Vermillion, 1978. The extension of calculus was estimated visually in all erupted teeth. Each teeth received a score ranging from 0 to 3. Minor scores indicated absence of calculus while higher scores indicated greater calculus accumulation on the tooth surfaces.
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Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Gingival Health
Periodontal status was evaluated regarding the patients' gingival health using the Gingival Index described by Loe, 1967. The gingival health was estimated clinically with a periodontal probe in all erupted teeth. Each teeth received a score ranging from 0 to 3. Minor scores indicated acceptable gingival health while higher scores indicated greater inflammation and unacceptable gingival health.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Plaque Accumulation
Periodontal status was evaluated regarding the amount of plaque accumulation using the Plaque Index from Loe, 1967. The extension of plaque was estimated clinically using a periodontal probe in all erupted teeth. Each teeth received a score ranging from 0 to 3. Minor scores indicated absence of plaque while higher scores indicated greater plaque accumulation on the tooth surfaces.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).
Retainers Survival Rates
The number and cause of failures for each patient was recorded during the 12-month follow-up. From these data, the total survival rate of the retainers was estimated as a percentage, as well as its major causes of failure.
Time frame: Evaluation was performed during the 12 Months of follow-up.
Patients' Perception
Patients' perception was assessed using a Visual Analogue Scale (VAS) containing a questionnaire with 9 questions related to the use of the retainers. Each question received a score ranging from 0 to 10. Minor scores indicated that the patient felt extremely uncomfortable during the retention period while higher scores indicated that the patients felt highly comfortable.
Time frame: Evaluation was performed at T0 (Debonding); T1 (3 Months Follow-up); T2 (6 Months Follow-up); and T3 (12 Months Follow-up).