Can shielded brackets reduce mucosa alteration and increase comfort perception in orthodontic patients in the first 3 days of treatment? A single-blind randomized controlled trial

Introduction

Orthodontic patients can experience pain and discomfort on the oral mucosa from trauma caused by friction with the brackets and the wires. In this split-mouth design, single-blind randomized controlled trial, we aimed to investigate whether brackets with a self-snapping customized plastic shield would induce less mucosa alteration and discomfort than those without the shield.

Methods

The overall sample comprised 42 patients (22 female, 20 male) from a government-funded orthodontic practice, with a mean age of 16.7 years. Eligibility criteria included, among others, no history of mouth ulcers or systemic diseases. Customized shields for the maxillary and mandibular brackets were fabricated and inserted on one side of the mouth. The null hypothesis was that bracket shielding would have no advantage. The primary outcomes were mucosal and discomfort assessments. As the secondary outcome, the numbers of spontaneous detachments of the shields were reported. Treatment allocation was mainly implemented using a random number table for selection of the intervention side. Only the raters in charge of assessing the oral mucosa were blinded to the side of the mouth where the shields had been placed. The mucosa was assessed by 3 calibrated raters at the following time points: immediately before bracket placement (baseline assessment, T0), 3 days after delivering the shields (direct assessment of intervention, T1), and 4 days after removal of the shields (indirect assessment of intervention, T2). The raters used a newly devised yardstick in which the higher the score, the more severe the alteration. Discomfort was assessed at T1 and T2 using a visual analog scale. The Mann-Whitney U test was performed at the 5% level of significance.

Results

Of 60 patients, 42 were eligible, and 35 were randomly selected to have one side of the mouth receive the intervention. Two patients discontinued the intervention at T1, and 5 stopped at T2. Seven additional patients were recruited and completed all time points. Thus, 42 patients participated at T0, 40 at T1, and 35 at T2. Thirty-five patients participated at all time points. At T1, no statistically significant difference in terms of mucosa alteration was observed between the 2 sides (median of all differences [MD], 0.0; 95% CI, 0.0-1.0; P = 0.11). The same occurred at T2 (MD, 0.0; 95% CI, 0.0-0.0; P = 1.00). The comfort level was statistically higher at T1 on the shielded side (MD, 14.0; 95% CI, 1.0-36.0; P = 0.04), whereas no difference was observed at T2 (MD, 0.0; 95% CI, 0.0-1.0, P = 0.81). No serious harm was observed.

Conclusions

The customized bracket shields were effective in reducing discomfort during the first 3 days of orthodontic treatment despite no significant difference in terms of visible mucosa alteration.

Registration

This trial was not registered.

Protocol

The protocol was not published before trial commencement.

Funding

Expenses for the fabrication of the shields were covered by the main author (L.P.B.P.). Orthodontic materials were from the Center for Dental Specialties in Cajazeiras, Brazil.

Highlights

  • The customized bracket shields seemed to reduce discomfort during the first 3 days of orthodontic treatment.

  • No difference in terms of visible mucosa alteration was noticed during the period of investigation.

Orthodontic treatment increases the risk of mucosal lesions in the first 2 to 3 weeks after bracket placement because of friction generated among the oral mucosa, the brackets, and the wire. Epithelial alterations may vary from minor wounds to large ulcerated areas and are considered quite uncomfortable. Injuries caused by multibracket orthodontic appliances are predominantly located on the buccal and vestibular mucosa as well as on the lower lip and are more common in female patients than in male patients.

Most preparations currently available to relieve mucosal discomfort contain benzydamine hydrochloride, which has an effect similar to a placebo. Chlorhexidine gluconate mouthwash showed some efficacy in reducing the breakout of traumatic oral ulcerations, but a preventive regimen in which it was used 3 times daily was considered difficult for patients to follow. Additionally, there are risks of enamel staining and unpleasant taste alterations. Because of the scarcity of pharmaceutical options and systemic drug release issues, patients are normally given wax to cover the protuberant parts of the brackets. However, the wax needs to be removed before each meal, is not well confined to the offending parts of the bracket, may be accidentally swallowed, and can interfere with wire-slot frictional forces if worn for a long time.

As previously reported, discomfort can negatively impact patients’ perceptions and quality of life during orthodontic treatment. Decreasing the incidence of mucosal lesions and optimizing comfort after bracket placement would be beneficial to orthodontic patients. This motivated us to test a method to improve the texture perception of brackets without interfering with their prescription and frictional levels. The following questions called for answers. Do conventional metal brackets need to have a better texture to prevent mucosal lesions? Would patients experience greater comfort with better textured brackets? In the era of evidence-based orthodontics, the answers to these questions should not be just implied. Until the final revision of this article, a PubMed search with a combination of the words “systematic review, bracket, and orthodontic” retrieved 48 titles. Of these, only one described the most common oral tissue side-effects of orthodontic treatment, but nothing was mentioned regarding either preventive or therapeutic measures. Of the 35 orthodontic titles available in the Cochrane Library, only one concerned the effects of nonpharmacologic interventions to alleviate pain associated with orthodontic treatment. However, this systematic review was still in the format of protocol and had not been concluded until the final revision of this manuscript.

Analyzing the options available in the market, we found 2 manufactured products. In the literature, we found an in-vitro study in which friction between the wire and the slot was not affected by a customized bracket shield.

Specific objectives and hypotheses

By temporarily covering brackets with self-snapping flexible plastic shields, the following null hypothesis was tested: There is no statistically significant difference in terms of both visible mucosal alteration and discomfort between shielded and nonshielded sides of the mouth after the first 3 days after bracket and shield placements. The same outcome is expected at 4 days after the removal of the shields.

The frequency of spontaneous failure of the shields will be reported to appraise their clinical applicability.

Methods

Trial design and any changes after trial commencement

This split-mouth single-blind randomized controlled trial was authorized by the ethics board at Potiguar University (Laureate International Universities) in Natal, Rio Grande do Norte, Brazil, according to official document number 100/2011. The superiority trial design was chosen to assess the advantages and clinical feasibility of covering orthodontic brackets with a smooth plastic shield to reduce mucosal alteration and discomfort. There was no change in the trial design after commencement.

Participants, eligibility criteria, and settings

Sixty consecutive patients with overbite of 4 mm or less who were referred to the outreach orthodontic service at the Center of Dental Specialties in Cajazeiras, Brazil, between July and November 2012 were considered as potential participants. The selection criteria immediately before the trial were as follows: (1) interest in participating in the trial, (2) normal soft tissues, (3) nonsmoking, (4) fully erupted permanent teeth except for second and third molars, (5) no current use of alcohol or illicit drugs, (6) no current or future intention to use a mouthwash solution, (7) no history of recurrent mouth ulcers, (8) no diagnosed systemic diseases, (9) no current or recent use of prescription medications, (10) no previous orthodontic treatment, (11) no current or past history of chemotherapy or radiation, and (12) reasonably symmetric mild crowding without crossbite.

Interventions

In this split-mouth design, customized bracket shields were the intervention under study, and the nonshielded contralateral side served as the control. The technique described elsewhere to fabricate the customized bracket shields was strictly followed. We decided to customize the shields for all maxillary and mandibular brackets, except for the molars. A stock of extra shield units was created for each tooth in case of attachment failure caused by mastication or brushing. The fabrication process started by inserting a 0.021 × 0.025-in steel wire into the 0.022 × 0.028-in slot of all maxillary and mandibular brackets containing hooks in the buccal segment. The wire was tied with elastomeric ligatures. Afterward, the slot and its entrances were filled with composite resin (TPH; Dentsply, Milford, Del) to relieve any interference from the shield with the sliding of the wire into the bracket slots. A 1-mm-thick vinyl acetate sheet (Whiteness; FGM, Santa Catarina, Brazil) was placed over the bracket-wire-ligature-resin set and thermoplasticized in a vacuum for a snug fit on the retentive sites of the brackets. Any unnecessary material was trimmed with either scissors or scalpel blades and polished with stone burs and scotch wheels for a fine acceptable finish. The same bracket-wire-ligature-resin sets were used to fabricate all shield units to be used in the trial, including those as refills.

The selected patients were initially examined by a panel of 1 orthodontist (L.P.B.P.), 1 periodontist (A.H.A.O.), and 1 general dentist (H.F.S.) in January and February 2013. These clinical sessions aimed to ensure that all patients had normal mucosa (score 0) before the trial. The assessment took place on a dental chair under the light of a dental reflector, with a mouth mirror. Each member of the panel worked independently and agreed not to exchange information. They had been calibrated with sample photographs and were blinded with regard to the side of the mouth that would receive the shield. All data were entered into a spreadsheet. The raters also took 4 standardized intraoral photographs (1 side view of each cheek, 1 frontal view of each lip) with a camera at 15.1 megapixels and electrofocus of 60 mm (EOS Rebel T1i; Canon, Melville, NY).

Immediately after the panel assessment at T0, the patients were transferred to another room to receive the same type of brackets, wires, and elastomeric ligatures that were used in the fabrication process of the shields. The orthodontists were previously instructed not to start any auxiliary or complex mechanics (eg, overlay wire, temporary anchorage devices, utility arches, cantilevers, elastics, and so on) during the trial. They were also aware of the importance of preventing any trauma to the mucosa and were asked to report any eventual trauma to the main investigator (L.P.B.P.). Written and verbal instructions regarding oral hygiene and diet were provided.

After bracket placement and wire insertion, 2 orthodontic assistants delivered the shields to the assigned sides using a random number table and the minimization method (see “Randomization”). They were also in charge of securing the concealment key for future information disclosure. Figure 1 shows a patient wearing the shields. All participants were instructed to replace the shields with new ones in case of detachment or distortion. A simple take-home chart was given to each patient with instructions to mark an “x” every time a shield had been replaced because of failure or because it was not worn. A package containing refills for each type of bracket was also provided. This whole process, from panel assessment to shield delivery, was considered to be the baseline time point (T0).

Fig 1
Intraoral frontal view at T0 showing the bracket shields on the left side.

Three days after T0 (T1), the 2 orthodontic assistants removed the shields and requested the patients to quantify with a visual analog scale the overall level of discomfort experienced on both sides during the past 3 days. The patients were left in private while using the visual analog scale. After this, they met with the raters again for the mucosal assessments and intraoral photographs.

Four days after removal of the shields (T2), the same process was repeated.

Outcomes (primary and secondary) and any changes after trial commencement

The primary outcomes were (1) severity of the mucosal alteration because of contact with the brackets and shields, and (2) the level of discomfort experienced by the patients on both sides (shielded and nonshielded). Two types of assessments were performed: (1) mucosal assessments at T0, T1, and T2; and (2) discomfort assessments at T1 and T2. There were no outcome changes after trial commencement.

Because of the lack of a visual method to assess mucosa, 2 experienced orthodontists (F.H.S.L.P. and L.P.B.P.) and 1 specialist in oral medicine (P.T.O.) with a high caseload of orthodontia-related referrals collaborated to devise a yardstick containing a written description ( Fig 2 ) and photographs ( Fig 3 ) illustrating the 6 possible scores, 1 representing the normal mucosa, and 5 the most severe alterations. Three meetings were held to review the literature, analyze the intraoral photographs, and discuss the clinical features of the proposed yardstick. The scale of this yardstick was carefully refined to include the most common tissue alterations caused by contact between brackets and lip and cheek mucosa.

Fig 2
Yardstick scores developed to assess bracket-induced mucosal alterations.

Fig 3
Photographs illustrating the scores of the yardstick.

The number of shield failures or detachments reported on the take-home charts helped to evaluate the clinical feasibility of this material and follow up patient compliance.

Sample size calculation

Based on a previous study, the soreness score mean difference of 1.47 was used as an estimate of the minimum difference to be detected. The standard deviation was 1.99. Until the date of this calculation, no study concerning oral-mucosa alteration scores had been published. Type I error was set at 0.05, and type II error was 0.20 (80% power). A bicaudal hypothesis test was performed; it indicated that a minimal sample size of 29 subjects would be necessary. It was decided to recruit a larger sample of 35 patients. For a thorough explanation, see “Participant flow” under Results.

Interim analyses and stopping guidelines

Interim analyses were not applicable. The authors decided that any unexpected harm would cause suspension and eventual termination of the trial. Lack of compliance in following the instructions would not lead to discontinuation of the orthodontic treatment.

Randomization (random number generation, allocation concealment, implementation)

Two trained orthodontic assistants, blinded to patient identification, used a random number table to select the participants based on sex and intervention side. For example, even numbers were encoded for the right side and male subjects, and odd numbers were encoded for the left side and female subjects. An inverted coding system was used when approximately 35% of the initial sample had been obtained. The minimization method proposed by Pocock and Simon was implemented when selecting the last 10 patients (30% of the sample) necessary to complete a sample size of 35 subjects. This method was repeated later when more patients joined the trial to compensate for exclusions and dropouts. Perfect equilibrium was not possible because 7 more subjects had to be recruited, and only 7 eligible ones remained on the list of consecutive patients ( Fig 4 ). The envelopes containing information on the intervention sides were locked safely in a cabinet until delivery of the shields. No rater had access to this information until full completion of the trial.

Fig 4
Participants’ flow diagram from eligibility assessment to data analysis.

Blinding

Until delivery of the shields, both trained orthodontic assistants were blinded regarding the patients’ original identification. The raters were blinded regarding the shielded sides, since they performed the mucosal assessments either before placement or after removal of the shields. In case of an emergency appointment, the shields were to be removed beforehand by a trained assistant and later replaced. Patients were repeatedly instructed not to share information regarding the shields with the raters.

Statistical analysis (primary and secondary outcomes, subgroup analyses)

All collected data were entered into an Excel 2007 spreadsheet (Microsoft, Redmond, Wash) by 2 investigators (L.P.B.P. and F.H.S.L.P.) and later transferred to SPSS software (version 17.0 for Windows; SPSS, Chicago, Ill) for statistical analysis.

Interrater agreement was based on all scores generated at T1 and T2. All photographs taken at T1 and T2 were mixed up, and 38 were selected at random to assess intrarater agreement. In this type of study, an assessment of intrarater agreement would be impossible without intraoral photographs. These photographs were trimmed in a similar manner showing the mucosa but omitting recognizable background images of brackets and gloves. They were randomly ordered in a PowerPoint file (Microsoft) and rated twice, 2 weeks apart. The level of agreement was assessed by the Spearman rank correlation coefficient, where 1 represents perfect agreement and 0 means lack of agreement. The Kolmogorov-Smirnov test was used to assess sample distribution.

Comparisons regarding mucosa and discomfort assessments were made between the shielded and nonshielded sides at T1 and T2 using the Mann-Whitney U test. It was decided not to run intragroup comparisons among T0, T1, and T2 because they were not suitable to test the null hypothesis. Instead, this could increase the odds of type I error because of several unnecessary statistical tests. At all occasions, the level of significance was set at 5%. An intention to treat analysis was not found to be necessary (see Discussion).

Methods

Trial design and any changes after trial commencement

This split-mouth single-blind randomized controlled trial was authorized by the ethics board at Potiguar University (Laureate International Universities) in Natal, Rio Grande do Norte, Brazil, according to official document number 100/2011. The superiority trial design was chosen to assess the advantages and clinical feasibility of covering orthodontic brackets with a smooth plastic shield to reduce mucosal alteration and discomfort. There was no change in the trial design after commencement.

Participants, eligibility criteria, and settings

Sixty consecutive patients with overbite of 4 mm or less who were referred to the outreach orthodontic service at the Center of Dental Specialties in Cajazeiras, Brazil, between July and November 2012 were considered as potential participants. The selection criteria immediately before the trial were as follows: (1) interest in participating in the trial, (2) normal soft tissues, (3) nonsmoking, (4) fully erupted permanent teeth except for second and third molars, (5) no current use of alcohol or illicit drugs, (6) no current or future intention to use a mouthwash solution, (7) no history of recurrent mouth ulcers, (8) no diagnosed systemic diseases, (9) no current or recent use of prescription medications, (10) no previous orthodontic treatment, (11) no current or past history of chemotherapy or radiation, and (12) reasonably symmetric mild crowding without crossbite.

Interventions

In this split-mouth design, customized bracket shields were the intervention under study, and the nonshielded contralateral side served as the control. The technique described elsewhere to fabricate the customized bracket shields was strictly followed. We decided to customize the shields for all maxillary and mandibular brackets, except for the molars. A stock of extra shield units was created for each tooth in case of attachment failure caused by mastication or brushing. The fabrication process started by inserting a 0.021 × 0.025-in steel wire into the 0.022 × 0.028-in slot of all maxillary and mandibular brackets containing hooks in the buccal segment. The wire was tied with elastomeric ligatures. Afterward, the slot and its entrances were filled with composite resin (TPH; Dentsply, Milford, Del) to relieve any interference from the shield with the sliding of the wire into the bracket slots. A 1-mm-thick vinyl acetate sheet (Whiteness; FGM, Santa Catarina, Brazil) was placed over the bracket-wire-ligature-resin set and thermoplasticized in a vacuum for a snug fit on the retentive sites of the brackets. Any unnecessary material was trimmed with either scissors or scalpel blades and polished with stone burs and scotch wheels for a fine acceptable finish. The same bracket-wire-ligature-resin sets were used to fabricate all shield units to be used in the trial, including those as refills.

The selected patients were initially examined by a panel of 1 orthodontist (L.P.B.P.), 1 periodontist (A.H.A.O.), and 1 general dentist (H.F.S.) in January and February 2013. These clinical sessions aimed to ensure that all patients had normal mucosa (score 0) before the trial. The assessment took place on a dental chair under the light of a dental reflector, with a mouth mirror. Each member of the panel worked independently and agreed not to exchange information. They had been calibrated with sample photographs and were blinded with regard to the side of the mouth that would receive the shield. All data were entered into a spreadsheet. The raters also took 4 standardized intraoral photographs (1 side view of each cheek, 1 frontal view of each lip) with a camera at 15.1 megapixels and electrofocus of 60 mm (EOS Rebel T1i; Canon, Melville, NY).

Immediately after the panel assessment at T0, the patients were transferred to another room to receive the same type of brackets, wires, and elastomeric ligatures that were used in the fabrication process of the shields. The orthodontists were previously instructed not to start any auxiliary or complex mechanics (eg, overlay wire, temporary anchorage devices, utility arches, cantilevers, elastics, and so on) during the trial. They were also aware of the importance of preventing any trauma to the mucosa and were asked to report any eventual trauma to the main investigator (L.P.B.P.). Written and verbal instructions regarding oral hygiene and diet were provided.

After bracket placement and wire insertion, 2 orthodontic assistants delivered the shields to the assigned sides using a random number table and the minimization method (see “Randomization”). They were also in charge of securing the concealment key for future information disclosure. Figure 1 shows a patient wearing the shields. All participants were instructed to replace the shields with new ones in case of detachment or distortion. A simple take-home chart was given to each patient with instructions to mark an “x” every time a shield had been replaced because of failure or because it was not worn. A package containing refills for each type of bracket was also provided. This whole process, from panel assessment to shield delivery, was considered to be the baseline time point (T0).

Apr 6, 2017 | Posted by in Orthodontics | Comments Off on Can shielded brackets reduce mucosa alteration and increase comfort perception in orthodontic patients in the first 3 days of treatment? A single-blind randomized controlled trial
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