This overview aimed to summarize the available systematic reviews that assess the effects of treatment with fixed orthodontic appliances (FOAs) on the periodontium. Unrestricted electronic search of nine databases and additional manual searches were performed up to January 2019. Systematic reviews and meta analyses that assessed the effect of FOAs on the periodontal parameters were included. The methodological quality of the included reviews was evaluated using the A Measurement Tool to Assess Systematic Reviews2 (AMSTAR 2). The initial search yielded 2529 articles from which 19 were included in the current study. AMSTAR 2 scores ranged from critically low to high quality. The quality of evidence ranged from very low to low. The superiority of the periodontal outcomes of self-ligating brackets over conventional brackets could not be proven. The available evidence regarding the effects of FOAs on the periodontium is controversial and of very low quality. The short-term effects of FOAs were temporary worsening the periodontal parameters. Some conclusions regarding the periodontal outcomes of self-ligating brackets could be withdrawn. Future high-quality trials are required. The review was registered at the International prospective register of systematic reviews with registration number CRD42018106662.
Enhancement of facial and dental aesthetics with preservation of the health and longevity of the masticatory apparatus is a common goal that is shared by the orthodontic and periodontal professions. The number of adult patients seeking orthodontic treatment with fixed appliances has increased steadily in recent decades. Additionally, a recent survey identified that 50% of Americans aged ≥30 years present with periodontitis. The existence of a strong relationship between periodontal and orthodontic treatments; especially in adult patients, triggered the clinicians and researchers from both ends to investigate a variety of questions pertaining to this interconnection. The number of publications evaluating orthodontic and periodontal interactions published in the years (2011–2016) was equal to that of those published in the previous 10 years (2000–2010), which, in turn, almost equals the one of the previous 60 years (1940–2000).
One of the previous assertions for orthodontic treatment was to prolong the longevity of the individual’s dentition through the correction of dental irregularities to allow better oral hygiene and reduce the incidence of gingivitis. On the contrary, damaging effects of orthodontic treatment on the periodontium were on top of the debatable topics in the dental field. It was stated that fixed orthodontic appliances (FOAs) produce significant clinical attachment loss and lead to a shift in the subgingival bacterial microflora and gingival inflammation regardless the oral hygiene level.
Orthodontic brackets and elastic modules interfere with the effective removal of plaque, thereby increasing the risk of gingivitis. Self-ligating brackets (SLBs) were supported by claims of superiority over the conventional brackets (CBs) regarding the bacterial retention and plaque accumulation. Other studies refuted the assumption of improved oral hygiene with SLBs when compared to CBs; and the controversy is still ongoing. Alternatives to FOAs include clear aligners that could have the advantage of reduced plaque accumulation and improved gingival and periodontal parameters when compared to FOAs.
The primary studies underpinning the orthodontic periodontal interrelationship suffer from low quality and lack of well-conducted large-scale research. Meanwhile, the number of systematic reviews (SRs) and meta analyses (MAs) focused on the orthodontic periodontal propinquity has rapidly escalated. The results of these reviews are sometimes contradictory, and their validity is highly influenced by their methodology.
The aim of the current study is to evaluate the methodological quality of the available SRs and MAs investigating the effects of FOAs on the periodontium to offer the clinician a summary of the current evidence and the quality of authentication.
This overview of systematic reviews followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The review protocol was registered at the International prospective register of systematic reviews (PROSPERO) with registration number CRD42018106662. Few changes have been made after the protocol registration including the change in the title.
Information sources, search strategy, and study selection
The electronic literature search was conducted in databases including PubMed, Embase, Cochrane Library, LILACS, Scopus, Web of science, SCIELO, Ovid, CINAHL via EBSCO in March 2018 and was conducted again in January 2019. No restrictions of language or publication date were applied. The implemented search strategy is presented in Appendix 1 .
Manual searching was performed in Google scholar, European Journal of Orthodontics, Journal of periodontology, Periodontology 2000, Journal of oral rehabilitation, Journal of clinical and oral investigations, Quintessence Publishing, American Journal of Orthodontics and Dentofacial Orthopedics, the Angle Orthodontist, and Seminars in Orthodontics. Bibliographies of the included full text articles were scanned for relevant studies. Two investigators independently performed and repeated the searches.
Unpublished literature was searched electronically at ProQuest and PROSPERO using the terms “orthodontic”, “periodont*”, “systematic review”, “meta-analysis” and “gingiva”. Authors were contacted to identify unpublished or ongoing systematic reviews and to clarify data as required.
The selection criteria that were applied for the inclusion of articles in this review are represented in Table 1 .
|Inclusion criteria||Exclusion criteria|
|Study design||SR or MA||Narrative reviews, commentaries on reviews and duplicate publications.|
|Design of the primary studies in the SRs||– RCTs
– Retrospective cohort studies
|– Animal studies
– Case reports
– Case series
– Expert opinions.
|Quality assessment||Validated tool for quality assessment of primary studies||No quality assessment|
|Population||Healthy periodontal patients undergoing fixed appliance therapy||Patients with periodontal disease or systemic conditions.
Subjects having adjunctive periodontal surgeries to fixed appliance therapy
|Intervention and comparator||Any type of active fixed appliance therapy that is compared to no treatment or treatment with another orthodontic appliance||Intervention has only removable appliances, fixed retainers|
|Outcomes||Include clinical periodontal outcomes.||Absence of clinical periodontal outcomes.|
After removal of internal and external duplicates, articles were screened based on title and abstract. When titles and abstracts were insufficient to decide, the full text of the article was acquired. Assessment of the reviews for inclusion was performed independently and in duplicate by two investigators. Disagreements regarding study inclusion were resolved by discussion to reach a final consensus
Data items and collection
Data extraction sheets were developed, and data were extracted independently by the two investigators . The collected data included: the design of the primary studies; the number of participants and their grouping, description of the interventions and comparator, the quality of the primary studies, the outcomes, results and conclusions.
Risk of bias/ quality assessment for the included reviews
The methodological quality of the included SRs was assessed independently by two reviewers using the A Measurement Tool to Assess Systematic Reviews (AMSTAR 2) checklist. The tool has 16 items to which responses are either yes, no, partial yes. The methodological quality was scored as High (Zero or one non-critical weakness), moderate (more than one non-critical weakness), low (One critical flaw with or without non-critical weaknesses), and critically low (more than one critical flaw with or without non-critical weaknesses).
Assessment of the overall quality of evidence across studies
The results of the SRs that were shown to have moderate or high quality according to the AMSTAR 2 checklist were used to construct the overall body of evidence for each of the main outcomes using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach. The GRADE profiler was used to evaluate studies for the methodological quality, risk of bias, directness of evidence, inconsistency, precision of effect estimates, and risk of publication bias. The GRADE result was interpreted as follows: “high quality” ‒ further research is very unlikely to change the confidence in the estimate of effect; “moderate quality” ‒ further research is likely to have an important impact on the confidence in the estimate of effect and may change the estimate; “low quality” ‒ further research is very likely to have an important impact on the confidence in the estimate of effect and is likely to change the estimate; and “very low quality” ‒ very uncertain about the estimate.
Study selection and characteristics
A total of 2524 articles were initially identified through electronic search, and five articles were obtained through manual searching. Initially, 55 articles met the inclusion criteria and were retrieved in full text. After reviewing the full texts, 36 articles were excluded. The most common reason for exclusion was the narrative nature of the reviews. The list of excluded studies is presented in Appendix 2 . We contacted the authors of four studies identified from PROSPERO to check the developing status of their SRs, however they didn’t respond. Finally, nineteen articles were included in the analysis. The detailed literature search process is presented in Fig. 1 .
Characteristics of included reviews
The data of the included SRs is summarised in Table 2 . From the included studies SRs, nine included only qualitative analysis and ten included MAs. Regarding the study designs of the included articles in the reviews, two SRs included only RCTs, six reviews included cross sectional and non-controlled studies. Seven reviews included RCTs and CCTs. Most of the remaining reviews included retrospective and prospective cohort studies.
|Study (SR/MA)||Number and Design of primary studies||Search strategy||Total number of participants and grouping||Intervention||Comparator||Outcomes||Quality of primary studies||Results||Authors’ conclusions|
|Objectives: to compare between SLBs and CBs regarding; oral hygiene, periodontal parameters, accumulation of S. mutans colonies, prevention of malodour|
|Arnold et al., 2016 (SR and MA)||8 studies (4 in MA)
7 RCTs (3 of them were split mouth)
Medline via Pubmed, CDSR, CENTRAL.
No language restrictions.
|326 subjects (including split mouth subjects)
All patients were adolescents
|SLB (active and passive)||CBs (elastomeric or stainless-steel ligatures)||Changes in periodontal or gingival inflammation indices including:
(PI), (GI), BOP, (PPD).
|Cochrane RoB tool
6 unclear RoB
2 high RoB
|After 3–6 months: PI: The mean change in the intervention groups was 0.14 higher
GI: The mean change in the intervention groups was 0.06 higher
PPD: The mean change in the intervention group was 0.01 higher
|There is no evidence to support the claim that SLBs have relevant clinical advantages over CBs regarding the periodontal health in adolescents with bonded brackets|
|Nascimento et al., 2014 (SR)||6 studies
CENTRAL; Ovid, PubMed and Bireme no language restrictions
|209||SLBs||CBs (5 studies elastomeric and 1 study metal ligation)||Adhesion and formation of S. mutans colonies||Jadad scale.
All studies had high quality
|The increase in oral microbiota (S. mutans and Lactobacillus) is associated with the use of orthodontic appliances with both CBs and SLBs with no differences between them||There is no evidence for a possible influence of bracket design (CB or SLBs) over colony formation and adhesion of S. Mutans|
|Yang et al., 2016 (SR & MA)||12 studies (8 in MA)
No split mouth studies
Medline via OVID, EMBASE via OVID, CENTRAL, World Health Organization International Clinical Trials Registry
Platform and the Chinese BioMedical Literature Database
311 SLB-treated patients and 264 CB-treated patients
|SLBs, (active and passive)||CBs||Discomfort
Oral hygiene evaluated through PI or bacterial colonization
|Cochrane RoB tool 10 studies unclear risk, 2 studies low risk of bias||The results showed passive SLB and CB did not differ significantly in plaque control [MD: −0.04, 95% CI (−0.30,0.22)].
SLB was not superior over CB in bacterial colonization.
|SLBs do not outperform CBs in reliving patients’ discomfort or promoting oral hygiene|
|Arbildo et al., 2018 (SR and MA)||12 studies (8 in MA)
3 split mouth
|(2012- December 2017) PubMed, Embase, SciELO, ScienceDirect, LILACS, BBO, Google Scholar and in the CENTRAL
Grey literature: SIGLE
|SLBs (active and passive)||CBs||PPD
|Cochrane RoB tool
All studies have high ROB
|PPD, BOP, GI and PI showed no significant differences between CB, active and passive SL brackets.||No differences were detected in the periodontal clinical effect of orthodontic treatment with conventional and self-ligating brackets|
|Longoni et al., 2017 (SR)||5 studies RCTs (1 parallel) quasi-RCTs (4; 3 split mouth and 1 parallel)||April 2016 LILACS, PubMed, SCIELO, Science Direct, Scopus, and Google Scholar.
Grey literature; Open Grey
|148||SLBs (active and passive)||CBs (3 studies elastomeric and 2 study metal ligation)||S. Mutans colonization||MAStARI checklist;
2 low risk,
3 moderate risk of bias
|No difference between S. Mutans in CB and SLB after 3 months by PCR. Stereomicroscope ST Mutans colonization was more in CB than SLBs after 1, 4, 5, 12, and 24 weeks.||SL brackets accumulate less S. Mutans than conventional metallic brackets.|
|Huang et al., 2018 (SR & MA)||4 studies (4 in MA)
PubMed, Ovid, Embase, and the Cochrane Library
|SLBs, CBs||CBs, untreated control||Oral malodour scores, PI, gingival index (GI), and periodontal pocket depths.||Cochrane RoB tool;
1 high risk of bias
|Fixed appliance versus control:
Malodour: CBs showed worse scores at the first week after bonding only.
PI: No difference between CBs and CG at 1 week.
At 1 month after bonding; significantly higher PI than control
GI: statistically higher in CB only at 1 month after bonding.
PPD: No significant changes over the 3-month period after bonding.
SLB vs. CBs:
Malodour scores were better in SLBs than CBs at 1 week.
No significant difference in PI and GI.
|FOAs are risk factors for malodour at one week after bonding with SLBs better than CBs.
PI was worse one month after bonding.
|Objective: To determine the correlation between gingival recession/ bone height and incisor inclination (labial movement of incisors) in non-growing post-orthodontic patients compared to adult untreated subjects or patients treated with different methodologies.|
|Aziz et al., 2011 (SR)||7 studies, all were retrospective; 2 had no control group||July 2010 Medline, PubMed, Embase, Web of Science, Cochrane Database of Systematic Review, CENTRAL||590 (190 were CG)||Fixed appliance with labial movement of incisors||Fixed appliances with no labial movement of incisors||Gingival recession||Custom made tool for quality assessment||Six studies denied an increased risk of gingival recession after labial advancement of mandibular incisors due to orthodontic treatment.
One study concluded that lower incisor proclination greater than 10° would inevitably lead to gingival recession.
|There is no association between appliance induced labial tipping and gingival recession.
Labial movement of incisors during orthodontic treatment is not contributing to gingival recession
|Tepedino et al., 2018 (SR)||2 studies
|June 2017. MEDLINE via
PubMed, EMBASE, Scopus, Web of Science, and Cochrane
Grey literature: OpenGrey.
|350 (150 untreated control, 26 fixed appliances with extraction, 174 non-extraction fixed appliances)
|FOAs (non-extraction basis)||Adult untreated subjects (1 study) or patients treated with FOAs on extraction basis (1 study)||Gingival recession and/or bone height, and post-treatment position of incisors||New Castle Ottawa scale. Moderate quality of studies.||Recession was significantly higher in treated patients compared to that in untreated controls but the difference was minor and clinically insignificant.
No correlation was found between the final inclination of lower teeth and gingival recession.
|No scientific evidence exists stating that proclination of incisors following orthodontic treatment with fixed appliance increases the risk of gingival recession|
|Objective: To assess the effect of comprehensive treatment with fixed orthodontic appliances on periodontal outcomes, inflammation indices and clinical attachment levels in adolescent and adult periodontally healthy patients.|
|Bollen 2008 (SR and MA)||12 studies; (8 in MA)
1 RCT, 3 CCT, 8 cross sectional studies excluded studies that assessed periodontal outcomes only at the time of appliance removal.
MEDLINE; Web of Science; and the CENTRAL, CDSR, DARE and Health Technology Assessment.
Grey literature: Clinicaltrials.gov, ProQuest
|1670; 821 intervention group, 849 in the untreated CGs.
|Fixed or removable appliances||No treatment||Alveolar bone loss, PPD, clinical attachment loss, gingival recession and gingivitis.||Cochrane RoB tool for RCTs, New Castle Ottawa scale for NRCTs. All had high risk of bias||Alveolar bone loss: was 0.13 mm (0.07–0.20) greater in the intervention group than controls.
PPD: intervention group had pocket depths that were, 0.23 mm (0.15–0.30) deeper than those of the control groups.
Gingival recession: The intervention group had gingival recession 0.03 mm (0.01–0.04) greater than did the control group.
|There is an absence of reliable evidence on the positive effects of orthodontic therapy on periodontal status.
The available evidence suggested a small mean worsening of periodontal status after orthodontic therapy.
|Verussio et al., 2018 (SR)||10 studies
7 RCTs (2 of them were split mouth), 3 CCTs
CENTRAL, Embase, Medline
|421, 274: Fixed appliances
78 removable appliances
69 untreated control
|Orthodontic treatment||Untreated patients or patients with different orthodontic treatment||BOP
|Cochrane RoB tool (results NR)||Patients undergoing orthodontic therapy show an increase in BOP, GI and PI
The highest inflammatory values were associated with fixed traditional orthodontic treatment
|The use of orthodontic appliances, particularly fixed appliances, can favour the increase of periodontal tissue inflammation.|
|Papageorgiou et al., 2017 (SR and MA)||9 studies (9 in MA) prospective non-randomized trials||February 2017
Medline via Pubmed, Scopus, Embase, Web of Knowledge, CENTRAL, CDSR, Virtual Health Library
Grey Literature: ISRCTN registry
|335; 231 FOAs 104 untreated CG
|FOAs||Untreated patients (3 studies only)
Other orthodontic treatment
|Clinical attachment loss during orthodontic treatment||ROBINS-I tool, 8 had moderate RoB, 1 had serious RoB||FOAs were associated with a clinical attachment loss of 0.11 mm, which was neither statistically nor clinically significant.
Untreated patients showed CAL 0.07 mm
Intrusion of anterior teeth was associated with a slight attachment gain of 0.63 mm
|Orthodontic treatment with fixed appliances might have little to no clinically relevant detrimental effect on the CAL|
|Cerroni et al., 2018 SR||5 studies cohort studies (prospective and retrospective)||From January 1997 to April 2017
Pubmed and Cochrane
|128||Fixed orthodontic appliances||NR||BOP
|Customized quality assessment tool (excluded 3 articles who had low quality)||Long term outcomes: studies reported no permanent effects on gingival status and that periodontal values tended to normalize 3 months- 2 years after fixed appliance removal.||There is moderate evidence that fixed appliances influence periodontal status. Orthodontic appliances developed generalized plaque accumulation and gingivitis in a short follow-up.|
|Objective: to assess evidence from human studies about qualitative changes in the subgingival microbiota/ plaque induced by orthodontic treatment.|
|Freitas et al., 2014 (SR)||4 studies (1 study prospective longitudinal, 1 study longitudinal, 2 studies NM)||May 2012
PubMed; Web of Knowledge and Ovid databases. (English language)
|139||Fixed orthodontic appliances||No control group||Microbial colonization in orthodontic fixed appliances||Customized quality assessment tool (excluded 4 articles who had low quality)||Placement of FOAs increased quantity and quality of oral microbiota.
Aa increased in subgingival plaque (2 studies)
Aa didn’t increase (1 study)
Increased Streptococci (1 study)
|Moderate evidence showed that FOAs influenced the quantity and quality of oral microbiota. This might be a transitional effect that depends on oral hygiene control.|
|Guo et al., 2017 (SR & MA)||13 studies (4 in MA) (two CCTs, three cohort studies and eight non-controlled Studies)||November 2016
PubMed, Cochrane Library, and EMBASE
|Fixed orthodontic treatment with metal brackets and bands||3 studies had untreated controls, 8 self-controlled studies||frequency of periodontopathogen in the subgingival plaques||MINORS moderate scientific evidence||Following FOAs insertion, the frequencies of Pg and Aa showed no significant change, the frequency of Tf significantly increased in short-term (0–3 months).
During >6 months observation, the levels of subgingival periodontopathogens exhibited a transient increase but decreased to the pre-treatment levels afterwards.
After removal of the FOAs, the 4 periodontopathogens showed no significant difference compared with before removal.
|The levels of subgingival pathogens presented temporary increases after FOAs placement and appeared to return to pre-treatment levels several months later. Orthodontic treatment might not permanently induce periodontal disease by affecting the level of subgingival periodontal pathogens.|
|Papageorgiou et al., 2018 (SR and MA)||24 studies
3 were RCTs,
5 were prospective NRCTs, and 16 were nonrandomized studies of unclear design
Medline via Pubmed, Scopus, Embase, Web of science, CENTRAL, CDSR, virtual health library, Google Scholar, Grey Literature: ISRCTN registry, ClinicalTrials.gov
|1271, only 4 studies had untreated controls||Orthodontic treatment with any fixed appliances||(1) Untreated subjects
(2) Other form of orthodontic treatment
|Qualitative and quantitative analysis of the subgingival microbiota.
Time-points were pre-treatment, short-term mid-treatment; long term mid-treatment; short-term post-treatment; long-term post-treatment.
|Cochrane’s RoB tool for RCTs, and a checklist based on Downs and Black tool for nonrandomized studies.
All studies had high RoB.
|The presence of Aa in the subgingival crevicular fluid of orthodontic patients was increased 3–6 months after FOAs insertion compared to untreated patients (RR = 15.54).
There was still increased subgingival prevalence of Aa (RR = 3.98) and Tf in orthodontic patients up to 6 months after appliance removal compared to untreated patients.
|Insertion of FOAs seemed to be associated with a qualitative change of subgingival microbiota, which reverts to some extent back to normal in the first months after appliance removal|
|Lucchese et al., 2018 (SR)||51 studies; (study designs were inadequately reported)||October 2017
PubMed, PMC, Scopus, Lilacs, Scielo, Cochrane Trial Library, Web of Science
|1863||Any type of orthodontic appliance.
CBs: (29 studies).
SLBs: (8 studies)
Lingual brackets (4 studies)
|NR||Qualitative change in oral microbiota after FOA insertion.
Periodontal parameters as PI, BOP
|Swedish Council on Technology Assessment in Health Care Criteria for Grading Assessed Studies’ methods.
1 study: high quality.
37 studies: moderate quality. 12 studies: low quality
|Orthodontic appliances influence the oral microbiota with an increase in the counts of S. mutans and Lactobacillus and in the percentage of potentially pathogenic gram-negative bacteria.||Orthodontic appliances significantly influence the oral microbiota with alterations appearing one month after the start of treatment.
Removable appliances had less impact on oral bacteria than fixed ones.
|Objective: to compare periodontal health in patients undergoing orthodontic treatment with clear aligners with that of those undergoing orthodontic treatment with fixed appliances.|
|Lu et al., 2018 (SR and MA)||7 studies (7 in MA)
All were Prospective cohort studies
|October 2017 Cochrane Library, EMBASE, PubMed, Medline, Chinese Biomedical Literature
Database, CNKI, and Wan Fang Data.
|368, 183 patients in the invisalign group and 185 patients in the CG||Invisalign||FOA||GI
sulcus bleeding index (SBI).
|The Newcastle-Ottawa Scale. All studies were of high quality (more than 7 stars)||GI and PPD: no significant difference between the invisalign group and the CG, at 1,3 and 6 months.
PI: Invisalign had a significantly lower PI, at 1 month (OR=−0.53), 3 months (OR=−0.69), and 6 months (OR=−0.91).
SBI: Invisalign showed a lower SBI, at 1 month (OR=−0.44), 3 months (OR=−0.49), and 6 months (OR=−0.40)
|The meta-analysis indicated that compared with FOAs, patients treated with invisalign had a better periodontal health.|
|Jiang et al., 2018 (SR/MA)||10 studies; (9 in MA)
3 RCTs, 7 cohort studies
PubMed, Web of Science, Cochrane Library, and Embase
|427 patients (190 patients used clear aligners, and 237 patients used fixed appliances)||Clear aligners||FOA||GI, PI, BOP, PPD||Cochrane RoB tool for RCTs, The Newcastle-Ottawa Scale for non RCTs
9 studies medium quality, 1 study high quality.
|Clear aligners were better than FOA for; PI (MD −0.53) moderate level of evidence
GI (MD, −0.27) – moderate level of evidence
PPD: (MD, −0.35) – low level of evidence.
|Clear aligners were better for periodontal health than FOAs and might be recommended for patients at high risk of developing gingivitis|
|Rossini et al., 2015 SR||5 studies (the results of 4 of them were included)
1 RCT, 3 prospective studies
Pubmed, National Library of Medicine’s Medline, Embase, CENTRAL, Web of Knowledge, Scopus, Google Scholar, and LILACS.
92 with FOA
71 with clear aligners
10 untreated control group
1 study had untreated control group
|GI, PI, BOP, PPD||A grading system described by the Swedish Council on Technology Assessment in Health Care.
Quality of the collected evidences was moderate (grade B) in all the studies
|A significant decrease of periodontal indices (GI, PBI, BoP and PPD) during CAT was observed in the analyzed sample of patients.||Periodontal health, as well as quantity and quality of plaque, were better during aligner therapy than during FOA treatments. (moderate evidence)|