Periodontal Management in Periodontally Healthy Orthodontic Patients with Fixed Appliances: An Umbrella Review of Self-Care Instructions and Evidence-Based Recommendations

The present umbrella review aimed to characterize periodontal self-care instructions, prescriptions, and motivational methods; evaluate the associated periodontal outcomes; and provide integrated, evidence-based recommendations for periodontal self-care in periodontally healthy orthodontic patients with fixed appliances. The presently applied study protocol was developed in advance, compliant with the PRISMA statement, and registered on PROSPERO (CRD42022367204). Systematic reviews published in English without date restrictions were electronically searched until 21 November 2022 across the PROSPERO Register and Cochrane Library, Web of Science (Core Collection), Scopus, and MED-LINE/PubMed databases. The study quality assessment was conducted through the AMSTAR 2 tool. Seventeen systematic reviews were included. Powered and manual toothbrushes showed no significant differences in biofilm accumulation, although some evidence revealed significant improvements in inflammatory, bleeding, and periodontal pocket depth values in the short term with powered toothbrushes. Chlorhexidine mouthwashes, but no gels, varnishes, or pastes, controlled better biofilm accumulation and gingival inflammation as adjuncts to toothbrushing, although only for a limited period. Organic products, such as aloe vera and chamomile, proved their antimicrobial properties, and herbal-based mouthwashes seemed comparable to CHX without its side effects. Motivational methods also showed beneficial effects on periodontal biofilm control and inflammation, while no evidence supported probiotics administration.


Introduction
Periodontal health is defined by the absence of microscopically and macroscopically detectable signs of inflammation interfering with periodontal physiology [1]. Given the well-known role of biofilm accumulation in gingivitis and periodontitis onset and development [2], the potential periodontal self-care and oral hygiene procedures are essential for maintaining periodontal health, supported by regular check-ups and professional operative sessions [1,2].
Fixed orthodontic treatment provides tooth movement to correct dental malocclusion through appliances, such as orthodontic bands and brackets, bonded to the tooth surface, archwires, ligatures, and auxiliaries [3,4]. Fixed orthodontic appliances often complicate oral hygiene procedures [5] and facilitate biofilm accumulation on both teeth and appliance surfaces [6][7][8].
Indeed, biofilm control and clinical periodontal inflammatory parameters are generally worse in orthodontic patients with fixed appliances than in patients with removable appliances and non-orthodontic patients [8]. Indeed, patients with fixed orthodontic appliances P-Population: periodontally healthy orthodontic patients (without age or gender restrictions) with fixed (vestibular or lingual) appliances; I-Intervention: periodontal self-care instructions, prescriptions, and motivational methods (any); C-Comparison: no intervention, placebo, between different interventions; O-Outcome(s): periodontal health status measured by periodontal indices (no self-report).

Search Strategy
Systematic reviews with or without a meta-analysis published in English without date restriction and related to periodontal self-care instructions, prescriptions, and motivational methods were searched electronically by two independent reviewers (F.D.S. and M.P.D.P.) through 21 November 2022, in the PROSPERO Registry and the Cochrane Library, Web of Science (Core Collection), Scopus, and MEDLINE/PubMed databases, combining the keywords illustrated in Figure 1 with Boolean operators, and applying the following filters: "Review (English)" and "refine: systematic review" in the Web of Science database; "Review (English)" in the Scopus database; "Systematic Review (English)" in the MED-LINE/PubMed database; "Keywords" and "Review" in the Cochrane Library; "Systematic review," "Meta-analysis," and "Completely published" in the PROSPERO register.

Study Selection and Eligibility Criteria
The collected citations were recorded, duplicates were eliminated using the reference management tool EndNoteTM (Clarivate), and the remaining titles were screened by two independent reviewers (F.D.S. and M.P.D.P.). The same two reviewers independently screened potentially relevant title-abstracts of systematic reviews with or without a meta-analysis.
Full texts of records that met the eligibility criteria and the ambiguous title-abstracts were obtained. No contact with the study authors was necessary because all full texts were available. The three authors independently reviewed the full texts (F.D.S., M.P.D.P., and D.C.). Any disagreement was resolved by discussion and consensus with a fourth author (F.D.A.) when necessary.
Inclusion criteria were as follows: systematic reviews with or without a meta-analysis published in English regarding periodontal self-care instructions, prescriptions, and motivational methods (of any type) in periodontally healthy orthodontic patients with fixed appliances. No restrictions were placed on the publication date or type of instructions, prescriptions, and motivational methods.
Exclusion criteria were as follows: duplicate records, commentaries, and editorials; and in vitro, preclinical, and clinical studies involving subjects with periodontitis, oral, and dental infections [39,40]; and patients undergoing orthodontic treatment with removable appliances; self-reports and concerns about periodontal status reported in the systematic reviews were not considered.

Data Extraction and Collection
Data were extracted independently by three authors (F.D.S., M.P.D.P., and D.C.) using a standardized data extraction form developed along the lines of the models proposed for intervention reviews of RCTs and non-RCTs [37]; a fourth author (F.D.A.) was consulted in case of disagreement.
From each systematic review with or without meta-analysis included in this review, the following data criteria were collected: -first author, year, journal, funding, quality of the study; -design and number of studies included in each review; -sample size, gender ratio, and mean age of the study population of each systematic review; -fixed orthodontic treatment performed: type and duration; -periodontal self-care instructions, prescriptions, and motivational methods provided, and comparison(s), if applicable; -evaluated clinical periodontal outcomes; -statistically significant results and conclusion(s) of the study.
In detail, periodontal outcomes included clinical indices, such as clinical attachment loss (CAL), periodontal probing depth (PPD), bleeding on probing (BoP), gingival bleeding index (GBI), bleeding index (BI), gingival index (GI), modified gingival index (MGI), plaque index (PI), and others, as well as radiographic, crevicular, and any other parameters reported in the systematic reviews.

Data Synthesis
A narrative synthesis was conducted that focused on the population studied, the intervention, and the outcomes. Data from the included studies were qualitatively summarized by a descriptive statistical analysis using Microsoft Excel software 2019 (Microsoft Corporation, Redmond, WA, USA): to characterize periodontal self-care instructions, prescriptions, and motivational methods provided and comparison(s); to assess clinical periodontal outcomes in relation to the periodontal self-care instructions, prescriptions, and motivational methods provided; to compare clinical periodontal outcomes following the provision of the periodontal self-care instructions, prescriptions, and motivational methods compared to no intervention, to placebo, and each other.

Quality Assessment
The quality of the systematic reviews included was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) 2 tool, accessed online on 22 November 2022 (https://amstar.ca), which evaluated for quality the systematic reviews of randomized and/or non-randomized studies [41].

Study Selection
The electronic search yielded 94 records from MEDLINE/PubMed, 79 from Scopus, 17 from the Cochrane Library, 176 from Web of Science (Core Collection), and 14 from the PROSPERO Registry, for a total of 380 records. Ninety-nine duplicate records were removed.

Periodontal
One study reported that probiotics reduced halitosis.
One study found that PT reduced PI and GI, while another study reported no significant influence on PI and GI. Motivational methods had significant advantages regarding PI in the experimental group over the control group at 1, 3, and 6 mo.
The remaining 281 records were screened, of which 214 did not meet the eligibility criteria and were therefore excluded.
Of the remaining 67 articles, the full texts were read. No contact with the authors was required to obtain the full text or further information.
An additional 54 articles were excluded because they did not meet this study's inclusion and exclusion criteria. Specifically: 28 studies involved subjects who did not undergo fixed orthodontic treatment; 6 did not evaluate periodontal parameters; 1 was not written in English; 1 did not apply an evaluable intervention; 1 included patients undergoing both fixed and mobile orthodontic treatment, and periodontal outcomes were not discernable; 1 systematic review did not include any study compliant with the eligibility criteria applied; 13 were narrative reviews.
The total sample size was 7.547, although one study [53] did not report the number of subjects involved. Participants, 1.835 males and 2.818 females, corresponding to a ratio of M:F = 1:1.5, were between 8 and 64 years old, although gender was not specified for 2894 subjects, and mean age was hardly ever reported.
Four studies [42,43,48,54] reported the absence of comorbidities that could affect the periodontal status and/or oral hygiene practices, while no study reported the presence of comorbidities.
One study [42] reported the minimum duration of fixed orthodontic treatment of 1 month; all other studies lacked data.

Reported Evidence on Periodontal Outcomes in Orthodontic Patients with Fixed Appliances in
In all cases, at least one control group with manual or powered brushing was compared with the corresponding one. In three studies [43,46,54], the investigated manual [43], orthodontic [43], or powered [43,46,54] brushing system was specified in more detail, and one study [49] indicated the type of antimicrobial gel associated with manual brushing.
The duration of intervention use was detailed in 4 of these studies [42,45,46,49], with a minimum duration of 15 days [45] and a maximum duration of 23 months [49].
Similarly, significant improvements in PI related to orthodontic toothbrushes were revealed in another study [45], although not associated with beneficial effects on GBI [45].
Regarding the powered toothbrushes, a significant improvement was noted for PPD values [54] in the short term; for GBI [54] and GI [54] in the short and long term; but not for BoP [46], GI [46], and PPD [54] in the long term.

Chlorhexidine-Containing Products in Periodontal Health Management of Orthodontic Patients with Fixed Appliances
The periodontal parameters were assessed in 3 studies in relation to the administration of chlorhexidine products [44,47,48]; as a mouthwash in 3 studies [44,47,48]; and in 1 study in the form of gels, toothpaste, or varnishes [47].
The durations of chlorhexidine product use and follow-up to assess periodontal parameters were also reported in all 3 studies [44,47,48], with a minimum duration of 1 day [48] and a maximum of 8 months [44].
Chlorhexidine gel did not significantly affect PPD values [47]. Similarly, varnish did not exert significant beneficial effects on GI and PI [47], or as toothpaste on GI and BI [23], albeit positively influencing OPI [47].

Other Organic Products in Periodontal Health Management of Orthodontic Patients with Fixed Appliances
Periodontal parameters were evaluated in subjects undergoing fixed orthodontic treatment and using organic products in 3 studies [27][28][29].
The organic product type or concentration was always reported. The duration of the administration was recorded in 2 studies [27,28], with 30 min [28] being the minimum and 6 months being the maximum [27].
The timing of follow-up was reported in 2 studies [28,29], with the shortest being 30 min [28] and the longest being 8 weeks [29].
One study [28] reported significant improvements in GBI and VPI in the group taking Matricaria chamomilla L, and PI and GI in the aloe vera group.

Probiotics in Periodontal Health Management of Orthodontic Patients with Fixed Appliances
The periodontal parameters were evaluated in subjects taking probiotics during fixed orthodontic treatment in 2 studies [50,51].
Probiotics' type and doses were clearly specified, and the duration of the intake ranged between 2 weeks [50,51] and 23.8 months [51]. The timing of follow-up was reported in only one study [50].
One study [50] evaluated PI and GI, but no evaluable measurements were reported; the other study [51] revealed no statistically significant improvements in GI.

Motivational Methods in Periodontal Health Management of Orthodontic Patients with Fixed Appliances
Periodontal parameters were assessed in subjects undergoing fixed orthodontic treatment and approached through motivational methods by computer aids or other means for maintaining good oral hygiene in 3 studies [34,52,53].
Periodontal parameters that significantly benefited from motivational methods were GI [34] and PI [34] at the 3-month follow-up but not PI at the 1-month follow-up [34]. GI and PI were also assessed in 2 other studies [52,53], but no evaluable values were reported. GBI and PI were recorded in relation to smartphone apps and showed significant improvements after 6 months of use, but not before at a 3-month follow-up [52]. Table 2 summarizes the main findings from the studies included in this umbrella review concerning periodontal outcomes in relation to self-care instructions, prescriptions, and motivational methods. Table 2. Synthesis of periodontal outcomes reported in the currently included systematic reviews related to the self-care intervention(s) investigated in periodontally healthy patients undergoing fixed orthodontic treatment. Evidence concerning manual and powered toothbrushes are in blue, chlorhexidine-containing products in yellow, other organic products in green, probiotics in fuchsia, and motivational methods in violet.

Discussion
Considering that lifelong periodontal self-care education, motivation, and guidance are prerequisites for maintaining healthy periodontal conditions [35], and that biofilm control may be challenging in periodontally healthy orthodontic patients with fixed appliances [6][7][8], the present review aimed to characterize periodontal self-care instructions, prescriptions, and motivational methods; to evaluate and compare the associated periodontal outcomes; and to provide integrated evidence-based recommendations for periodontal self-care in periodontally healthy patients undergoing fixed orthodontic treatment.
A total of 17 studies [27][28][29]34,[42][43][44][45][46][47][48][49][50][51][52][53][54] were included in the present umbrella review, with a total of 7547 periodontally healthy patients between the ages of 8 and 64 years undergoing fixed orthodontic treatment. The present study population reflects the sociodemographic characteristics of the current population of orthodontic patients [55]. Indeed, while orthodontic patients aged 19 years or older were rare in the 1960s, the number of adults undergoing orthodontic treatment increased exponentially by 2000. In 2006, older (≥40 years) adults comprised an estimated 4.2% of the orthodontic population, with 20% of patients over 60 years of age. Notably, considering the higher prevalence of periodontitis with increasing age [56], only periodontally healthy adult orthodontic patients fit the topic of the present study. Consistent with the present study's sample, which has an M:F ratio of 1:1.5, a higher prevalence of female patients with fixed orthodontic appliances is generally found in every other age group [55]. None of the studies included in this umbrella review described limiting health impairments or comorbidities that might affect periodontal health status, but few reported their absence. It is well-known that some physical (e.g., disabling osteoarthritis, rheumatoid arthritis, and other musculoskeletal disorders [57]) and mental [58,59] disabilities can make it difficult to practice good oral hygiene.
Additionally, systematic conditions (e.g., neoplastic diseases) that may affect the periodontal supporting tissues independent of dental plaque biofilm-induced inflammation have been reported [60]. Given the above, the presence/absence of limiting health impairments and comorbidities that potentially affect periodontal health status and/or oral hygiene should be considered a confounder in this type of study and should be specified.
Most of the studies reviewed did not specify a fixed orthodontic treatment duration. However, this does not seem relevant because enamel demineralization and soft tissue inflammation may develop rapidly within the first few months of treatment, depending more on the individual's susceptibility than on the treatment duration [61]. Brushing teeth as a daily routine is the most important healthy behavior to maintain oral and periodontal health [22]. However, the effectiveness of toothbrushing in removing biofilm depends on several factors, including the frequency and duration of daily toothbrushing [61], motivation, as well as knowledge, and manual dexterity [62]. Indeed, people without dental training rarely manage to clean more than 30-40% of their dental cervical area by manual toothbrushing [63,64], whereas dental professionals manage to clean more than 90% of their gingival margins [65].
Powered toothbrushes were introduced in the early 1960s as an alternative to manual methods [62]. They can be classified according to their mode of action (rotational oscillation; lateral oscillation; counter-oscillation; circular; ultrasonic; ionic), and their advertising slogans promise they provide a superior clean [66]. This assumption is supported by the systematic review by Yaacob et al. [67], which showed a slight, albeit significant, advantage of certain designs of electric toothbrushes over manual toothbrushes in reducing oral biofilm and preventing gingivitis. However, this study did not focus on orthodontic patients.
However, according to the findings from all the systematic reviews included, no significant differences between manual toothbrushes and electric toothbrushes in the efficacy in the mechanical control of bacterial plaque could be highlighted in patients undergoing fixed orthodontic treatment. ElShehaby et al. [42], comparing manual with powered toothbrushes, found slight and non-significant differences in GI, PI, and OPI at 4-and 8-week follow-ups. Accordingly, Kaklamanos et al. [46] found no difference between powered and manual toothbrushing in gingival inflammation (GI and BoP score). Conversely, Al Makhmari et al. [54] found an overall statistically significant advantage of powered over manual toothbrushes in terms of GI, GBI, and PD, but the authors acknowledged that more studies with low risk of bias, longer follow-up time, and broader samples are needed to provide solid evidence [54].
Pithon et al. [43] reported conflicting results comparing powered and convectional manual toothbrushes in orthodontic patients and concluded that brushing with a manual toothbrush twice daily for 1 to 3 min effectively reduced PI [43].
A study included in this systematic review analyzed orthodontic toothbrushes: special manual devices designed to provide adequate oral hygiene in orthodontic patients by using a V-shaped groove with shorter nylon bristles along the long axis of the toothbrush head to increase the contact area between the bristles of the toothbrush and the orthodontic appliance [25]. The orthodontic toothbrushes achieved more extensive plaque removal, although no differences in gingival bleeding were observed. This highlights the need for further clinical studies to obtain clinical recommendations [25].

Chlorhexidine-Containing Products
Chlorhexidine (CHX) is a cationic compound capable of binding negatively charged bacterial cell walls and causing the rupture of bacterial cytoplasmic membranes, leading to cell death [68]. CHX is effective against both Gram-positive and Gram-negative bacteria, including aerobes and anaerobes [69].
The bactericidal spectrum and high substantivity in the oral cavity make CHX the gold standard for the chemical control of oral biofilm [26]. Accordingly, it is the most common antiseptic used for a limited period as an adjunct to mechanical therapy for periodontitis [70,71].
Regarding the efficacy of CHX in reducing plaque and gingival inflammation in orthodontic patients with fixed appliances, relevant evidence emerged from studies included in the present umbrella review. Karamani et al. [48] found significantly lower gingival inflammation and plaque accumulation in patients using CHX mouth rinses than in nonusers. Hussain et al. [47] compared CHX-containing products (mouthwashes, toothpaste, gels, tooth varnish) with placebo or sodium fluoride products and found significant clinical improvements after administering CHX-containing mouthwashes, with a reduction in gingival inflammation (lower GI and BI score) and plaque accumulation (lower PI score). A dose-response relationship was noted, as 0.12% CHX mouth rinses had half the effect on GI as 0.20% CHX rinses. Periodontal probing depth (PPD) values were also significantly reduced by CHX mouth rinses [47].
In addition, a greater reduction in gingival index (GI) and bleeding index (BI) values was observed in the group using CHX-containing mouth rinses than in the group using fluoride-containing (sodium fluoride) mouth rinses. This result should not be surprising because fluoride ions are known to prevent tooth demineralization by inhibiting carbohydrate utilization by oral bacteria [72,73], although they do not alter the biofilm ecosystem [74]. Accordingly, the potential anti-plaque effect of some fluoride salts (especially stannous fluoride) may be due to the tin content [75].
The efficacy of CHX mouth rinses was also reported by Pithon et al. [44], who studied different types of mouth rinses containing organic molecules and fluorides (CHX, octedins, essential oil, cetylpyridium, sodium fluoride, and amine fluoride/stannous fluoride) and found them effective in reducing biofilm accumulation (low PI) in orthodontic patients. Finally, Fatima et al. [49] found a significant improvement in gingivitis but not PPD after applying chlorhexidine or other antimicrobial gels.
Conversely, no clinically relevant benefits were found for CHX-containing toothpastes, gels, or varnishes [47]. The authors believe such findings may be ascribable to the greater ease and related treatment compliance of mouthwash compared to gels and other formulations, especially in patients with fixed orthodontic appliances [47]. Karamani et al. [48] also found a significantly lower gingival inflammation and plaque accumulation in patients with CHX mouthwashes than in control groups [48]. The efficacy of CHX mouthwashes was also reported by Pithon et al. who investigated different types of organic molecules-and fluorides-containing mouthwashes (CHX, octedine, essential oil, Cetylpyridium, sodium fluoride, and amine fluoride/stannous fluoride) and found them effective in the reduction of the accumulation of plaque (lower PI) in orthodontic patients. Lastly, Fatima et al. [38] noted a significant improvement in gingivitis by using chlorhexidine or other antimicrobial gels, but no significant differences in the probing depth between antimicrobial agents and the control group.
However, despite the beneficial effects of CHX-containing products on achieving and maintaining periodontal health, the case-specific benefit/risk ratio should be accurately assessed before CHX administration [76]. Indeed, from a clinical point of view, the potential adverse effects of CHX, such as dry mouth, change in taste, discoloration of the teeth, and hypersensitivity reactions, should be considered [76].

Other Organic Products
In addition to CHX, other organic molecules have been shown to exert antimicrobial effects against oral species, including other biguanides (octenidine, alexidine), quaternary ammonium salts (cetylpryridinium and benzalkonium chloride), and pyrimidine derivatives (hexidine) [77]. Periodontal outcomes following the administration of these antimicrobials were also evaluated in the study mentioned above by Pithon et al. [44].
More recently, the potential beneficial effects of natural products, such as herbs and plant extracts, on oral mucosa and gingiva have been investigated [78]. In detail, herbal mouthwashes containing natural compounds with anti-inflammatory and antimicrobial activity, such as the essential oil of Matricaria chamomilla L. [78], Sanguinaria canadensis, Eucalyptus globulus, Salvadora persica, Azadirichta indica [79], Zingiber officinale [80], Prunus mume [81], and Aloe vera [82] have been tested as methods for biofilm control. According to Panagiotou et al. [27], some herbal mouthwashes (notably Matricaria chamomilla L., Zingiber officinale, and Prunus mume) appeared to be effective in reducing oral biofilm accumulation and/or gingival inflammation in patients with fixed orthodontic appliances. Papadopoulou et al. [28] also found promising results for an aloe vera mouth rinse, honey ingestion, and chamomile mouth rinse in reducing biofilm and gingival bleeding.
However, when comparing the efficacy of herbal mouthwashes with CHX-based ones in patients undergoing fixed orthodontic treatment, Kommuri et al. [29] reported conflicting results, as few studies were found with a high risk of bias.

Probiotics
According to the definition of the WHO/FAO [30], probiotics are living microorganisms that provide health benefits to the host when administered in certain amounts. Among the beneficial effects of probiotics, there is some evidence of their role in disrupting gingival biofilm and modulating the host immune response. However, the exact mechanism of action is still unknown [31,32]. Since biofilm has been implicated in the pathogenesis of caries and periodontal disease, and the latter is also associated with the host response, it is suggested that probiotics may be useful in the prevention and treatment of these diseases [83,84]. However, the evidence for probiotics' clinical efficacy in the prevention of caries and periodontal health management is still inconclusive [33,85,86].
Probiotic administration has also been suggested to be effective in improving or maintaining oral health in patients treated with fixed orthodontic appliances, as they are at a greater risk for caries and gingivitis development due to biofilm accumulation favored by the appliances [87,88].
However, the two relevant systematic reviews we currently considered showed contradictory results. According to Hadj-Hamou et al. [51], there is moderate evidence that probiotics do not affect gingival inflammation in these patients. Instead, Pietri et al. [50] found that the administration of probiotics decreased the number of pathogenic bacteria in oral biofilm and/or saliva, facilitating the maintenance of oral health. They also reported a possible mild effect of probiotics in reducing biofilm accumulation and gingivitis. However, the studies included in their systematic review had a moderate risk of bias due to heterogeneity in the methodology, and the recorded outcomes remain questionable because the preliminary sample size calculation was hardly performed [50].
Therefore, the results of both studies should be interpreted with caution. From a clinical perspective, further well-designed RCTs with a longer follow-up period are needed to evaluate the role of probiotic administration in maintaining oral health in patients undergoing fixed orthodontic therapy.

Motivational Methods
Dental caries, biofilm accumulation, and gingivitis are primarily due to unhealthy self-care behaviors. Patients are usually instructed in oral hygiene relevance and related procedures by dentists. However, conventional oral health education, which focuses on disseminating information and giving instructions, often does not lead to a change in misbehavior [89].
According to Huang et al. [34], patient motivation may be critical in maintaining a behavioral change. Indeed, when investigating different motivational methods, they found a statistically significant improvement in plaque accumulation (lower PI score) and gingival inflammation (lower GI score) in subjects who underwent motivational interventions compared to control subjects.
In orthodontic patients, Sharif et al. [52] concluded that apps and mobile phone-based reminders could be effective behavior-change techniques to improve compliance with oral hygiene instructions during treatment.
Data collected by Migliorati et al. [53] showed that regular patient motivation sessions with one-to-one instruction by a hygienist also help maintain good oral hygiene in patients undergoing fixed orthodontic treatment. Electrically powered and manual toothbrushes did not show significant differences in the plaque index (PI) [42,43], so they can be considered equally effective for mechanical biofilm control in orthodontic patients. Instead, orthodontic brushes could provide better control of biofilm accumulation [45].
CHX mouthwashes, but not other CHX-containing products (gels, varnishes, pastes), may be better used to control plaque accumulation in addition to tooth brushing, but only for a limited period [44,47,48]. Considering the side effects of CHX, other organic products or herbal mouthwashes may be recommended, as they significantly reduced the PI score [27,28,44], and their effectiveness seemed comparable to CHX ones [29].
Probiotics did not show significant results in terms of PI score improvements [50], while motivational methods have proved to be a simple and effective means of maintaining good biofilm control [34,52,53].

Gingival Inflammation Reversal
Conflicting findings related to the type of toothbrush used and gingival inflammatory parameters. Indeed, some results suggest that the use of electric or manual (including orthodontic) toothbrushes has no direct beneficial effect on inflammatory periodontal parameters-gingival bleeding index (GBI) [42,45], GI, or bleeding on probing (BoP) scores [46]-and PPD [49]. Other findings, instead, revealed an improvement in these indices, particularly GI, GBI scores, and PPD scores, in the short term [54] with powered toothbrushing.
CHX-based [47,48] and herbal-based mouthwashes [27][28][29] are associated with lower GBI, GI scores, and PPD values than control groups. Therefore, the use of these antimicrobial agents to maintain oral gingival health in patients with fixed appliances should be considered.
In contrast, no beneficial effects on GI currently support probiotics administration [50,51]. Active reminders to motivate patients on a regular basis represent an effective intervention to limit gingivitis in orthodontic patients [34,52,53].

Evidence-Based Periodontal Self-Care Recommendations for Periodontally Healthy Orthodontic Patients with Fixed Appliances
Patients should be encouraged to brush their teeth at least twice daily with a manual toothbrush or an electric toothbrush for 1 to 3 min, depending on their preference [42,43,45,46,49].
If orthodontic patients with fixed appliances are unable to control biofilm accumulation with conventional toothbrushes, the use of specifically designed devices (orthodontic toothbrushes) may be prescribed [45].
A risk-benefit assessment should always be performed before prescribing chlorhexidine, because, despite being the best-studied and most effective oral antiseptic [97], its use may be associated with adverse reactions [98].
If the patient's periodontal conditions are considered at high risk for disease development, and no history of hypersensitivity reactions to CHX is reported, chlorhexidinecontaining mouthwashes should be administered in the absence of hypersensitivity reactions. Concentrations of 0.12% to 0.20% should be prescribed, as the efficacy of lower concentrations remains uncertain [99], and higher ones unnecessarily increase side effects [98]. The CHX regimen was described in a recent Cochrane systematic review [76].
If the patient's periodontal conditions are considered at low/moderate risk of disease development or a history of type I and type IV hypersensitivity reactions associated with oral use of CHX is reported, other organic molecules (octedin, cetylpyridinium chloride, sodium fluoride, amine fluoride/tin fluoride, essential oil)-containing mouthwashes should be preferred [27][28][29]43]. These mouthwashes should be administered according to the manufacturer's instructions.
Routine oral hygiene instructions should be repeated during treatment and reinforced by motivational methods. Cell phones are essential tools for improving adherence to oral hygiene instructions, especially in children and adolescents [34,52,53]. Figure 3 summarizes the evidence-based recommendations for periodontal management in periodontally healthy orthodontic patients with fixed appliances.
The heterogeneity of the extracted data, especially regarding the timing of the followup, has precluded the possibility of performing a meta-analysis, which is the study's main limitation. In addition, heterogeneous data, particularly regarding the timing of follow-up, and missing data on administration regimens and intervention duration, precluded the possibility of conducting a meta-analysis, which is the study's main limitation.
However, the present umbrella review may be the first to comprehensively characterize periodontal self-care instructions, prescriptions, and motivational methods, attempting to provide recommendations for periodontal self-care instructions and methods in periodontally healthy orthodontic patients with fixed appliances.
Further studies should highlight the most effective self-care instructions and methods, individually and in combination, to define standardized periodontal health management protocols for orthodontic patients with fixed appliances.

Conclusions
The present umbrella review included 17 systematic reviews investigating the periodontal parameters in healthy subjects in fixed orthodontics in relation to manual, orthodontic, or powered toothbrushes; CHX-containing or other organic products; probiotics; and motivational methods.
Powered and manual toothbrushes showed no significant differences in the PI score increase. However, some evidence revealed a significant improvement in GI, GBI, and PPD in the short term offered by powered toothbrushes.
CHX mouthwashes, but no other CHX-containing products (gels, varnishes, pastes), have been proposed to better control biofilm accumulation and gingival inflammation in addition to toothbrushing, but only for a limited period.
The effectiveness of other organic products due to their antimicrobial properties was reported for aloe vera and chamomile and seemed comparable to CHX without its side effects in the long term, particularly for herbal-based mouthwashes.
Motivational methods also showed beneficial effects on biofilm accumulation and gingival inflammation, while no evidence has been found on the effectiveness of probiotics.
Therefore, at the current state of knowledge, the gold standard for biofilm control and gingival inflammation reduction in subjects with fixed orthodontic treatment may be the combination of manual, orthodontic, or powered brushing; motivational aids; and organic products, or the short-term use of CHX mouthwashes.
Future research should determine standardized periodontal self-care protocols for optimal periodontal health management in orthodontic patients with fixed appliances.

Conflicts of Interest:
The authors declare no conflict of interest.