Can lingual spurs alter the oral health-related quality of life during anterior open bite interceptive treatment? A systematic review

ABSTRACT Introduction: The use of lingual spurs has been described as one efficient option, with great stability of results, but with scarce information of toleration for use in the mixed and permanent dentition phases. Objective: The purpose of this study was to assess the impact of lingual spurs on the oral health-related quality of life of children and/or adolescents during anterior open bite treatment. Methods: The review was recorded in the PROSPERO database. Eight electronic databases and partial gray literature were searched, without restrictions until march 2022. A manual search was also performed in the references of the included articles. Studies assessing the impact of lingual spurs on the oral health-related quality of life were included. Risk of bias was assessed using JBI or ROBINS-I tool, according to the study design. The level of evidence was assessed through GRADE. Results: Five studies met the eligibility criteria. Two non-randomized clinical trials had a serious risk of bias. Of the case-series studies, two had a low risk of bias and the other, a moderate risk of bias. The certainty of the evidence was classified as very low for all the evaluated results. In general, the studies reported an initial negative impact with the use of lingual spurs, however this was transitory in nature. A quantitative analysis was not performed due to the great heterogeneity between the studies. Conclusion: Current evidence, although limited, suggests that lingual spurs have an initial transient negative impact during interceptive treatment. Additional well-conducted randomized clinical trials are needed.


INTRODUCTION
Anterior open bite can have a significant impact on the quality of life in children and adolescents, due to the severe aesthetic-functional impairment, 1,2 and the orthodontic treatment is able to improve quality of life in such patientes. 2 However, long-term treatment stability can be a challenge. 1 This is probably due to the difficulty in recognizing the multifactorial aspect of the etiology of anterior open bites, which may include deleterious habits and oral breathing, vertical growth pattern, abnormal size and incorrect tongue function 3 . Previous studies have correlated incorrect tongue posture as the main risk factor for relapse. 4,5 Although several approaches regarding anterior open bite treatment are available, there is still no consensus on which therapy would be able to control in the long term the oral dysfunctions and myoskeletal problems present in this malocclusion. 6 Among the options, lingual spurs is one approach that uses intraoral devices. 6 They serve as a reminder for the patient to interrupt tongue pos- Some systematic reviews have evaluated the efficiency of different early treatment protocols used to correct anterior open bite. 9,10 However, there is no systematic analysis of the evidence on the impact of lingual spurs on quality of life. Accordingly, the aim of this review was to investigate the impact on the quality of life, in children and adolescents, of using spurs for anterior open bite treatment.

PROTOCOL AND REGISTRATION
This systematic review was registered at the PROSPERO database (CRD42020203780) and performed according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. 11

ELIGIBILITY CRITERIA
The following selection criteria were adopted:

INFORMATION SOURCES
The following databases were searched: PubMed, Scopus, Web of Science, Cochrane Library, LILACS and ClinicalTrials. Grey literature was consulted through OpenGrey and Google Scholar.
A hand search was conducted by reading the references of the included articles, for eventual additional relevant studies.
No restriction on language or date of publication was applied.
The search was continued until March 15th, 2022.

SEARCH STRATEGY AND STUDY SELECTION
The databases were independently searched by two reviews (LBM and SMMR). Disagreements were settled by discussion and consensus and, when necessary, a third author's opinion (SCCJ) was consulted. The search strategy was developed through a combination of Mesh, entry terms and keywords related to the PICO strategy using Boolean operators (Appendix 1).
After the searches, the results were imported to a reference manager software (EndNote, x9 version; Clarivate Analytics, Philadelphia, PA). Duplicate studies were excluded by automatic and manual assessment. The selection process was performed in two phases. In the first phase, the title and abstract that did not follow the established eligibility criteria were excluded.
In the second phase, the articles remaining from phase I were assessed by reading the full-text. In addition, the reference list of the selected studies were also evaluated to retrieve new articles that followed the eligibility criteria.

DATA ITEMS
Data collected from each article included: authors, year of publication, country, study design, participants, age, follow-up, statistical analysis, methods of evaluation and results (Table 1)

RISK OF BIAS ASSESSMENT
For the case-series, the risk of bias was performed following the Joanna Briggs Institute (JBI) Critical Appraisal Checklist tool. 12 The checklist for case-series studies uses ten criteria. Each component was rated "yes", "no", "unclear", or "not applicable". With 1-3 "yes" scores, the risk of bias classification is high; 4-6 "yes" scores, the risk is moderate and 7-10 scores, there is low risk of bias ( Table 2).

The ROBINS-I tool Risk of Bias in Non-Randomized Studies of
Interventions) 13 was used in nonrandomized studies. This checklist presents three main evaluation domains. The risk of bias was assessed for each domain and classified as "low", "moderate", "serious", "critical" or "no information" (Table 3). Each analysis was made by two authors (LBM and SMMR), and disagreements were solved by a third reviewer (SCCJ).

LEVEL OF EVIDENCE
The included articles were given a narrative score related to the  14 This tool considered five aspects for rating the quality of evidence as high, moderate, low or very low.

SYNTHESIS OF METHODS
The results are provided in a narrative synthesis of the included studies that comprised study type, sample size, age of population, intervention group, comparison group and outcome.

STUDY SELECTION
The electronic search revealed a total of 1,007 citations: 195 from  Table 4.

STUDY CHARACTERISTICS
The characteristics of the included studies are described in Table   1. Selected studies were published between 1970 and 2020. [15][16][17][18][19] Two studies 15,16 were nonrandomized trials (one was prospective 15 and the other was retrospective 16 ), and three studies were case-series. [17][18][19] The follow-up period ranged from 3 months 19 to 20 months. 16 The sample size ranged from 12 17 to 72 individuals 18 The average patient age was from 4 to 17 years among the studies. [15][16][17][18][19] Only one study 16 did not describe the mean age of patients.
Both sexes were included. [15][16][17][18][19] The methods used to evaluate the impact of lingual spurs on the oral health-related quality of life of children and/or adolescents during anterior open bite treatment were questionnaires [15][16][17][18][19] and pain scales. 16,19 Three studies used their own questionnaires developed for their research. 15,17,18 One study conducted interviews with parents or guardians with a rating scale. 16 It is important to highlight that only one study 19 used a pain scale and validated questionnaires to assess the repercussions of oral health problems on the quality of life of children.
In relation to lingual spur types, two studies bonded lingual spurs to the palatal and lingual surfaces of the maxillary and mandibular incisors 17,19 . In one study, treatment consisted of a mandibular lingual arch and spurs 18 . In another, two different types of spurs were used: bonded lingual spurs, compared with conventional spurs 15 . In a fifth study, a palatal crib with spurs was used. 16 Moda

RESULTS OF INDIVIDUAL STUDIES
The use of lingual spurs in early treatment for anterior open bite has some initial negative impacts on the oral health-related quality of life, the average open bite treatment duration was between 3 to 12 months. In the studies, there was the application of the questionnaire during 15 and before and during treatment. 17,18,19 There was a questionnaire application during treatment with 4 objective questions for speech, feeding, tongue pain and discomfort, and use of spurs. The spurs were well-tolerated after 7 days during the functions of chewing and feeding. 15 After a psychological evaluation, the results include a temporary period of disturbance, difficulty in speech, and some difficulty in eating, ranging from 1 day to 3 months. 16 In this study, the difficulties were in the categories of speech, feeding, aesthetics, and tongue pain at the beginning and end of treatment.
The spurs were well-tolerated by all individuals, classified as 'easy' and 'neutral' in all categories, except for feeding and tongue pain. In the 'aesthetics' category, they were all scored as 'easy'. 17  Speech and chewing problems were the most common functional complications developed during lingual spur therapy; [15][16][17][18][19] and these were also reported as decreasing over time. Sleep disorders such as restlessness and nocturnal enuresis were also reported in a transient manner. 16 One study reported greater acceptance of bonded lingual spurs, compared to conventional spurs. 15 One study concluded that treatment with spurs does not seem to be related to the development of other parafunctional habits, such as nail biting, body scratching, nibbling hair or clothes and snapping fingers. Nevertheless, patients became more restless, bored and they cried more easily. 16

SYNTHESIS OF RESULTS
A meta-analysis was not considered in this systematic review

BIAS RISK ASSESSMENT
Regarding the case-series studies, two resulted in a low risk of bias 17,19 and one in a moderate risk. 18 In one of the studies, the instrument used to measure quality of life was not validated. In addition, there was a large difference in proportion between genders, the authors used inadequate statistical tests, which may induce to some bias, and the follow-up results were not clear. 17 Another study 18 used a convenience sample, determining its allocation through the participants' date of birth. The instrument used for assessing the impact on quality of life was developed by orthodontists, physiologists and psychologists, and the authors did not clearly report the inclusion criteria. After email contact, the authors clarified that they established a division by age and psychological criteria.
In addition, there is heterogeneity between the studied groups, which can generate greater variability. 18 In the third study, the authors did not clearly report the outcomes or results of the bias. In addition, they presented retrospective definitions of some assigned aspects of interventions. 16 The other study also used a non-validated instrument to measure quality of life 15 adapted from a previous study. 17 The researchers determined a rule of deterministic attribution as a way of trying to guarantee an exact proportion between the groups, alternating the records received from each patient, which can generate important selection bias. In addition, the control group was compared with different subjects from the experimental groups. 15 Blinding was not considered a determining factor for the anal-  Tables 2 and 3.

Other considerations
Oral health-related quality of life (rated with: questionnaires ) Of the three studies, two showed an initial negative impact of a transitory nature. Except for one, who completed minimal initial discomfort with no changes over time.
Discomfort, speech problems and chewing were the most reported oral symptoms. lack of clarity as to the outcomes or results of follow up. 17,19 Therefore, confidence in the estimate of the effect is limited.

VERY LOW IMPORTANT
In this way, there is a possibility that the real effect is substantially different (Table 5).

SUMMARY OF EVIDENCE
Among the five studies included in this review, all described that the physical and psychological negative reactions found during the lingual spur treatment were of a transitory nature.
There was a tendency for these reactions to decrease throughout treatment and were tolerated by patients, with a range of 7, [15][16][17][18][19] 15 to 20 days of adaptability. 17,18 The evaluated studies were characterized as two prospective 15 and retrospective 16 non-randomized clinical studies, and three case-series. [17][18][19] Two studies had a serious risk of bias 15,16 , two others had a low risk 17,19 and one, a moderate risk. 18 The impact of lingual spurs on children's oral health-related quality of life may have been influenced by some factors, such as different perceptions between genders. One study observed that this sensation was more tolerated by girls. 18 However, the painful perception can have a biological influence among children eight years or older, as boys tend to be reluctant to express emotions related to pain, 20 so these influences must be considered.
Oral speech and chewing functions, previously impaired by the presence of an open bite, were evaluated in the five studies. [15][16][17][18][19] The findings showed that the presence of spurs altered speech at the beginning of treatment, but it was readjusted within a maximum of 3 weeks, 16 with greater perception in older children 18 . What the authors seem to agree on is that speech was substantially improved after treatment with spurs and, consequently, open bite closure, corroborating the findings in the literature. 21,22 The effects on chewing due to the use of spurs were also transitory, according to the authors. However, the adaptation period was slightly longer, about 30 days, 17 and younger children had greater perception. 18 Numerous physiological factors can influence chewing, such as the number and type of teeth, and these can change with children's age. These changes can influence the stabilization and occlusion of the jaw and, thus, the chewing function of younger children. 22 Other negative impacts that were reported were that children became more upset, irritated and cried more easily, ranging from 1 to 30 days, ceasing in 1 to 3 weeks. 16 In addition, they had temporary sleep disturbances and became more restless. 16 This observation of emotional disorders may be associated with fear and anxiety of dental treatment. There is evidence that psychological aspects influence the patient's perception of dental care, so that the patient's level of anxiety, state of attention and emotions can make them overestimate the pain they will feel. 23 Dental Press J Orthod. 2023;28(1):e2321298 About the impact of patient losses during follow-up on the result, it is known that it is important to consider all individuals included in the sample and not just those who completed the entire follow-up period. However, studies suggest that the impact of the loss depends on the number of individuals who abandon or are excluded. 24 Although there is no established limit from which there would be a significant compromise in the results, it is suggested that studies with loss of patients above 20% should not be accepted. 24 In this review, only two studies reported losses, 17,19 one loss in one study 19 and two in another. 17 Regarding the positive impacts, studies suggest the advantage of spurs, as it is a fixed device, which does not depend on the patient's collaboration, it is quick to install, can be used in both the upper and lower arches at a low cost. 25 In addition, they were considered good aesthetic options. 15 It is recognized that facial appearance plays an important role in the judgment of personal attractiveness and also in the development of self-esteem. 26 Understanding the importance of this subject for further clinical clarification, a randomized clinical trial was found in progress,

LIMITATIONS/RECOMMENDATIONS
The case-series [17][18][19] and the non-randomized clinical studies 15,16 included in this review had some limitations in their methods and study design, which impacted their risk of bias assessment.
The variation in the methods of assessing oral health-related quality of life may have been a confusing factor for the results found in the studies included in this review, given that there was no homogeneity in the choice of the questionnaires used. [15][16][17][18][19] Biases related to questionnaire-based studies are common, since the results depend of the honesty of the patient and the accuracy of their responses. In addition, it should be taken into account that children can adapt or get used to their health conditions over time and can respond with lower impact scores when a questionnaire is reapplied later. 28 Still, the lack of data on dropouts could have some influence on the result of the impact of the perception of spurs related to quality of life 17,19 . Losses of patient during the study can affect the conclusions, since the unknown response of these patients to treatment may change the results of the comparison. 24 Of the five studies, only one 19 used a validated questionnaire for this purpose. The importance of investigating this issue more precisely is known, which is using valid and reliable tools to obtain consistent information to provide additional data for making clinical decisions or assessing treatment success. 29