Main findings in the context of the existing evidence and interpretation
Although the negative impact that malocclusion has on children’s OHRQOL2,3,4,5,6, limited high-quality evidence has been reported related to patients’ perception during orthodontic treatment. Most of the outcomes evaluated in orthodontic research focused on morphologic changes and do not address patients’ perspectives28. Especially, there is only one RCT that explored the longitudinal impact of AOB treatment with a palatal crib in OHRQOL during treatment compared with no treatment, reinforcing the need for more prospective clinical trials11.
Besides the palatal crib, there are various alternatives to treat children with AOB; among them, bonded spurs have been reported as an effective and practical treatment option14,19,21. However, no strong evidence regarding patients’ perceptions within this protocol has been reported27. In this regard, the present study brings important information comparing the impact of alternative approaches including lingual spurs during AOB correction in the mixed dentition. The results of this RCT provides high quality evidence on this topic.
In this study, two treatment protocols were used to correct the AOB. Both protocols used spurs and the SBU additionally used posterior build-ups to control the vertical development of posterior teeth. The effects of these protocols in the craniofacial and dentoalveolar structures have been previously reported23,37. AOB was corrected mainly by dentoalveolar effects, lingual inclination and extrusion of incisors and anterior dentoalveolar vertical development. Similar effects were reported in previous studies14,18,19,20. This study focused on the OHRQOL evaluated 1 and 12 months after the installation of the appliances. Adaptation and discomfort perceived during the first month of treatment were also evaluated.
The evaluation time had a statistically significant effect on the overall OHRQOL (Table 3). Among all domains, the improvement on functional limitation domain was apparently the most important contributor to the observed overall effect. Functional limitations include questions that associate teeth with difficulty for eating, chewing, speaking and sleeping32. It could be speculated that 1 month after the start of treatment, patients still experience functional problems associated with the intraoral appliances. Previous studies reported that during orthodontic treatment, the OHRQOL can worse slightly because of the appliance discomfort7,38. This temporary worsening due to the functional limitation because of the presence of the appliance was also reported during crossbite treatment with rapid maxillary expansion in children39. No significant occlusal vertical correction of AOB should be expected 1 month after the appliance installation14,19. Functional problems during speaking, chewing and swallowing are usually observed in AOB malocclusion due to the lack of contact between anterior teeth and anterior tongue posture. An altered functional pattern is present and is mainly caused by deleterious habits9. When the spurs are placed in the mouth, the imbalance caused by the altered function is broken and patients can experience greater functional problems due to limitations on anterior tongue posture during function. Therefore, functional limitations at 1 month can be associated with the presence of the spurs and AOB. This finding should be confirmed in future studies that include pretreatment assessments and an ideal untreated control group.
The improvement of functional limitations from the first to twelfth month of treatment observed in this study can be explained because of the expected patients’ adaptability to the appliances and clinically significant correction of AOB. Correction of AOB creates an adequate morphologic environment for an adequate function19,25,26. This was also reported to occur during other orthodontic treatments. OHRQOL values can be higher during the first weeks of treatment, but they progressively decrease with malocclusion correction7,11,38,39. These findings point to the dynamism of OHRQOL evaluation12.
The significant interaction between treatment and time detected for the functional limitation domain showed a statistically significant decrease of ‘functional limitations’ scores from the first to the twelfth month in the S group only. It could be speculated that the presence of posterior build-ups can cause greater functional limitations, partially restricting a significant improvement on this domain in the SBU group. Improvements of functional limitations with time in AOB treatment with spurs have been reported in previous studies19,25,26. In AOB patients, anterior tongue posture is critical. Spurs directly act on tongue posture and function. Their effect has been reported to have a neurophysiologic basis for changing tongue position and function, establishing a new neuromuscular pattern with time13,24. This can improve the functional limitations. In addition, one study evaluating tongue pressure during AOB with palatal crib therapy showed significant decreases in resting and swallowing tongue pressures, suggesting tongue adaptation during treatment40. Future RCTs with spur therapy associating these evaluations should be performed. It could be thought that after the removal of the spurs, the improvements in OHRQOL might be even greater38.
An additional questionnaire was used in this study to further evaluate the adaptation and discomfort during the first month of treatment19,25,26. Patients demonstrated easy adaptation to speaking, chewing, swallowing and appearance during the first month of treatment41, with similar results in both groups (Tables 2 and 4). This has been reported in previous studies and reinforces the easy adaptability that children can have during orthodontic treatment with spurs19,25,26. Within the easy adaptation range, higher scores were obtained for chewing and lower scores for appearance. Scores for chewing and appearance were expected to be higher in the SBU group because of the presence of the build-ups in the maxillary posterior teeth. However, no significant effect of treatment type on any adaptation outcome was detected.
Tongue-related discomfort and Posterior teeth-related discomfort were evaluated in both groups immediately after (T0), first day (T1), 1 week (T2) and 1 month (T3) after the installation of the appliance (Table 2). A time effect was evidenced only for Tongue-related discomfort variable, independent of the treatment type (Table 5). Similar discomfort on the tongue between groups were expected because both groups had lingual bonded spurs. Tongue-related discomfort scores are expected to decrease over time. Greater reduction of discomfort can be expected 1 week and even more 1 month after the installation of the appliances. Spurs caused discomfort on the tongue during the first days but this discomfort progressively decreases during the first month of treatment, as previously reported19,25,26. This initial and temporary discomfort was also reported for other orthodontic therapy in children39. A greater discomfort on the posterior teeth was expected for the SBU group because of the presence of build-ups. However, no effect of treatment type or time was evidenced for posterior teeth-related discomfort (Table 5).
Patient-centered outcomes are very important to be analyzed because they assist clinicians to understand how the treatment approaches are perceived by the patients and how they affect their OHRQOL. The instruments used in this study were in accordance with previous reports11,19,25,26,32,33. The questionnaires were self-administered avoiding any type of coercion during answering. A very detailed explanation about the questions and scoring system was given to all patients and parents. Patients were able to ask regarding doubts to their parents and/or the researcher at any moment. The understanding of the questions was double checked by the researcher.
Overall OHRQOL scores improves during AOB correction with spurs, associated or not with posterior build-ups, from the first month to twelfth month of treatment. Patients easily adapted to treatment with spurs during the first month of treatment. Discomfort was present during the first days and is expected to decrease after 1 week of treatment. The importance of the findings of this study is related to the evaluation of patient-centered outcomes using a high-quality study design (RCT) that usually is lacking in this specific population. This study brings new information regarding OHRQOL during AOB treatment in children and reinforces previous findings related to adaptation and discomfort with spurs. Communication between clinicians, patients and their legal guardians regarding what patients will experience during treatment is strongly recommended. Considering the patient-centered outcomes from the present study, the success rates on AOB correction, the similar skeletal and dentoalveolar effects between spurs only and spurs/build-ups23,37, spurs only therapy seems to be the more practical and efficient treatment alternative for AOB patients.
Limitations
OHRQOL and discomfort are dynamic11,12,33. Ideally, OHRQOL should be also evaluated before treatment and at least 1 month after the removal of the appliances. This study attempted to measure the impact of the interventions using the CPQ8–10 from the first to the twelfth month of treatment. The OHRQOL questionnaire was only applied one and 12 months after the installation of the appliances. Spurs were maintained in both groups after 12 months, as active retention in patients that showed correction and as active treatment in patients that still needed some correction. Thus, evaluation after full appliance removal was not possible in this planned 12-month assessment. Although OHRQOL data from additional time points would be beneficial to have a complete longitudinal assessment of the effects of the treatment approaches on OHRQOL, similar results between groups including greater improvement on functional limitations and overall scores of OHRQOL would be expected38. A previous study evaluated OHRQOL of children with anterior open bite (AOB) before, 3 months after appliance delivery (fixed palatal crib) and 1 month after appliance removal11. The authors showed that correction of AOB had a positive impact on their OHRQOL, whereas the failure to treat this condition had a negative impact. Extrapolating the results of the previous study11, a decrease on these scores would be expected from pretreatment to 12 months after the installation of the appliances. Nonetheless, future studies should involve examining patients both before appliance delivery and after appliance removal.
Generalizability
This single-center study included patients from a specific age range. Thus, the results of this study should not be generalized to children with other ages or treated with different therapies.
