Eligibility criteria

This review was conducted through October 2018 and was structured in accordance with PRISMA guidelines, the Cochrane Handbook for Systematic Reviews of Interventions, and the checklist for reviews. The protocol was registered with the National Institute for Health Research (PROSPERO) with registration number CRD42015023514 for systematic reviews. (http://www.crd.york.ac.uk/PROSPERO). The PICO(T/S) format used for systematic reviews was used in this review (Table 1).

Inclusion criteria

This review included all articles that met the following criteria with no language restriction: human studies (including randomized clinical trials, controlled clinical trials, cohorts, cases and controls, case series- with more than 10 patients), evaluating the CSF-related periodontal condition as an adjuvant procedure in the possible stability of orthodontic treatment and assessing the effectiveness of this procedure in the retention phase over a period longer than or equal to 1 year.

Exclusion criteria

The literature search excluded studies in patients who had syndromes or were systemically or periodontally compromised, the use of CSF for purposes other than retention, combination treatments, and patients with additional periodontal treatments.

Search strategy

Detailed search strategies were developed for PubMed and EMBASE (Excerpta Medica Database). The database search was performed using MeSH (Medical Subject Headings), keywords, and Boolean Operators (OR, AND) as follows:

#1 “tooth crowding” OR malocclusion OR “crowding tooth” OR “inadequate tooth alignment” OR recurrence OR relapse OR recrudescence OR “periodontal disease” OR “gingival recession” OR “periodontal pocket”

#2 retention OR retainers OR “orthodontic retainers”

#3 #1 OR #2

#4 fiberotomy OR fibrotomy OR “circumferential supracrestal fiberotomy” OR “gingival fiber surgery”

#5 #3 AND #4

In addition, other sources of information such as gray literature and works cited within the articles found were taken into account.

Values studied

Assessing data validation and extraction

The hypothesis was: is circumferential supracrestal fiberotomy effective as an adjuvant procedure in the stability of orthodontic treatment during retention and what are its effects on the periodontal condition after it has been performed?

Two researchers (L.M.A.G; L.M.R.M.) read and analyzed the documents’ titles, abstracts and full texts independently. Disagreements between these two reviewers were resolved by discussion. When no agreement could be reached, a third reviewer was consulted (A.Z.R.). The following data were extracted and recorded for each article: bibliographic reference, type of study, type of outcome and conclusions.

Bias risk and quality assessment of the included studies

Two tools were used for methodological quality assessment depending on study type. For observational studies, an adapted version of the Newcastle-Ottawa Scale was used to assess methodological quality. For Randomized Clinical Trials (RCTs) and Controlled Clinical Trials (CCTs), the Cochrane collaboration tool was used to assess bias risk²⁰ (Tables 2 and 3).

Search results

The search strategy identified 81 potentially eligible articles in the databases (EMBASE and PubMed) and 4 articles from other sources of information for a total of 85 articles (Table 4). Of these, 30 were duplicates in the databases, 31 were excluded because of the title and/or abstract, and 3 were not found in full text. Thus, the full text of the 21 selected articles was reviewed, but 16 articles did not meet the inclusion criteria (study type, follow-up period shorter than one year and additional procedures besides fiberotomy) (Figure 1).

Source: by the authors

Figure 1 Flowchart 

Studies included

In total, five articles were selected for review (a randomized clinical trial,⁷ three non-randomized clinical trials,^11-13 one retrospective cohort study,¹⁶ Tables 5 and 6). No sample calculation was performed in any of the five studies. A total of 48 subjects were examined in observational studies and 509 subjects in clinical trials.

Methodological quality of the included studies, evaluation of orthodontic treatment relapse and periodontal condition

Evaluation of orthodontic treatment relapse and periodontal condition

Three studies reported an appropriate method for evaluating orthodontic treatment relapse using Little’s irregularity index^7,11,12 and one study used rotation evaluation by degrees.¹⁶

The periodontal condition described by Hansson¹³ reported an adequate measurement method. Two studies used a periodontal probe.^11,12 One study was not clear on the method used7 and another study did not report results in this regard.¹⁶

Orthodontic treatment relapse after performing CSF in the short and long term

Rye (1983)¹⁶ used degrees of rotation of each tooth to evaluate post-orthodontic relapse. The control group showed an average rotational relapse of -7.1 degrees (range: -19.9 -5.7 degrees), while the experimental group had an average relapse of -4.6 degrees (range: -18.3 -9.1 degrees). The difference in rotational relapse averages was statistically significant between the control and experimental groups (p < 0.01). The relapse rate in the control group was 39.0%, and 22.8% in the experimental group.¹⁶

Edwards (1988) conducted a follow-up clinical study for 15 years, reporting that the control group had greater relapse in the anterior segment of both maxilla and mandible in the long term. The average maxillary relapse at T4 was 49.80%, and 53.55% in the mandible. In the experimental group, CSF showed greater success in controlling relapse of the anterior segment in the maxilla and mandible, with an average of 20.80% and 34.97% respectively.¹²

Tanner et al (2000) observed increases per follow-up year in terms of average relapse of 25% in the maxilla and 63.6% in the mandible in the control group. In the experimental group there was an average relapse of 1% in the maxilla and 1.5% in the mandible.¹¹ In a 2.4 years post-CSF follow up, Wang et al (2003) reported that irregularity increased in all groups at T2 and T3 and that it was significantly greater in the control group between T2 and T3 (p <0.05)⁷. In the experimental group, the average relapse decreased by 21.61% compared to the control group.

Periodontal conditions after performing CSF in the short and long term

In their study, Hansson et al (1976) showed the average plaque index in CSF-treated teeth at the mesial (x̅ = 0.77), buccal (x̅̅ = 0.55) and lingual levels (x̅ = 0.93), compared to those not treated in mesial (x̅ = 0.97), buccal (x̅ = 0.60) and lingual (x̅ = 0.93), as well as the average gingival index between CSF-treated teeth at the mesial (x̅ = 0.97), buccal (x̅ = 0.77) and lingual levels (x̅ = 0.97) and those not treated in mesial (x̅ = 1.03), buccal (x̅ = 0.70) and lingual (x̅ = 0.83). No statistically significant differences were found in relation to the three recorded measurements and the two indices obtained. No significant differences were identified between teeth evaluated in the same jaw in relation to average depth of the gingival sulcus measured at the buccal (treated x̅ = 1.70 vs. untreated x̅ = 1.77), mesiobuccal (treated x̅ = 2.27 vs. untreated x̅ = 2.20) and distobuccal (treated x̅ = 2.13 vs. untreated x̅ = 2.23).¹³ Edwards (1988) compared the level of epithelial adhesion (treated x̅ = 0.0 vs untreated teeth x̅ = 0.0) and keratinized gingiva loss (treated 0.0 vs. untreated teeth x̅ = 0.0) None of the two groups showed statistically significant differences at 1 and 6 months.¹² Tanner et al (2000) observed no significant alterations in the level of epithelial adhesion. Sulcus depth remained unchanged from T1 to T2 and T3, and the width of adhered gingiva showed no change after the surgical procedure.¹¹ Similarly, Wang et al (2003) found no periodontal tissue compromise when performing CSF.⁷ Rye (1983)¹⁶ was the only study showing no results concerning the periodontal condition following CSF.¹⁶

Summary of key results

The results from other studies are consistent with the results of the studies evaluated for this review,^{7,11-13,16,21-23} which show that CSF-plus an adequate retention period-is a successful approach in reducing short-term and long-term orthodontic recurrence (moderately recommended, based on level-B evidence-multiple studies of moderate quality).^{7,11-13,16,24}

Quality of studies, limitations and possible biases in the review process

Except for the study reported by Rye in 1983,¹⁶ the studies by Edwards in 1988,¹² Tanner et al 2000¹¹ and Wang et al in 2003⁷ used Little’s irregularity index to assess the degree of relapse. This method-commonly used in the literature-was described by Little as an index taking a horizontal line as a reference to measure the displacement of the anatomical points of contact of each lower incisor, that is, the sum of the five displacements represents the relative degree of anterior irregularity.¹⁵

Regarding the stability of periodontal tissues following fiberotomy, the studies evaluated different clinical parameters. Hansson et al, in 1976,¹³ described the plaque index, gingival index and gingival sulcus depth. Edwards in 1988¹² and Tanner et al in 2000¹¹ evaluated changes in the position of epithelial adhesion, gingival sulcus depth, and changes in keratinized gingiva width. However, Tanner et al do not show statistical results related to the reported clinical findings.

The heterogeneity of the clinical parameters evaluated and the measuring instruments used results in a big methodological problem for the interpretation of results, taking into account the variability of the clinical criteria used to determine periodontal condition. This particularity allowed us to generate only qualitative general analyses on the impact of CSF on periodontal tissues.

Another limitation has to do with the methodological quality of the included studies. 80% of the studies had a moderate bias risk and only one article had a high bias risk (20%). The evidence supporting the clinical applicability of CFS in orthodontic stability is poor, although it suggests that this procedure could be effective in controlling short and long-term post-orthodontic relapse. Additional studies are needed to provide stronger available evidence in the future.

Agreements and disagreements with other studies

Similar previous studies, such as that of Ahrens et al in 1981,²³ suggest that surgery to remove the influence of supracrestal fibers on orthodontic treatment relapse is an effective method for achieving short-term stability, with statistically significant results as a lower degree of relapse is observed when compared with a control group, although it is important to mention that this study has a variation in terms of the surgical technique performed, as well as very short follow-up time (30 days). The same author reports that there was no alteration at the periodontal level following the procedure.

The study by Rinaldi in 1979²⁵ evaluated the periodontal condition 4 months after CSF, finding out that gingival sulcus depth was maintained without any alteration. The author also reports the apical migration of epithelial adhesion in the lingual area of anterior teeth in both the maxilla and the mandible. However, this clinical finding was minimal, without any adverse consequences on periodontal tissue. It concludes then that the surgical technique carried out according to Edwards is a benefit in young patients, helping to maintain the stability of treatment and periodontium.¹²

Other studies found in this search but not included in the systematic review because of failure to meet the inclusion criteria show that CSF is a procedure that does not cause periodontal alterations while decreasing orthodontic relapse,^5,22 agreeing with the results of the five articles used in this review.

Protocol for performing fiberotomy

The periodontal fibers that influence stability are periodontal ligament fibers and supra-alveolar fibers; the former are completely remodeled only after 2 to 3 months and the latter are stable and have a slower rotation. In the CSF technique, transseptal fibers are cut interdentally into the space of the periodontal ligament, healing between 7 and 10 days. The study by Shekar et al in 2017²⁶ concluded that fiberotomy is not indicated during the active movement of teeth or in the presence of gingival inflammation. When performed on healthy tissues after orthodontics, there is minimal insertion loss.

There is no specific protocol on the ideal method and time to perform fiberotomy. Reitan²⁷ reported that the largest relapse occurs within 5 hours of orthodontic elimination. Therefore, Proffit²⁸ suggests that this procedure should be performed at the end of treatment, a few weeks before removing the orthodontic devices. Similarly, Taner et al,¹¹ Rye ¹⁶ and Wang et al⁷ report the completion of surgery before brackets removal. On the other hand, Edwards indicates the procedure at the time of brackets removal.¹²

Other treatment modalities to ensure orthodontic treatment stability

Although studies evaluating other procedures in addition to fiberotomy were excluded as potential confounding factors, some authors^6,7 describe re-approximation as a way to improve the results obtained with fiberotomy and thus ensuring the long-term stability of orthodontic treatment.

According to these authors, re-approximation performed in a precise and conservative manner increases the long-term stability of the anterior mandibular segment. However, the combination of fiberotomy plus re-approximation cannot be considered as the permanent solution for all problems associated with treatment.⁶

Using laser or electrosurgery

The use of fiberotomy to decrease relapse following orthodontic treatment has shown to be highly effective in several studies; however, although this can be considered a non-invasive technique, there are some associated morbidities such as bleeding, pain and/or discomfort on the patient.²⁹ Alternative methods have therefore been described to improve these conditions, such as the use of electrosurgery and laser.^29-33

Using laser to perform fiberotomy shows numerous benefits over the conventional technique, since it is considered that with this technology patients experience minimum pain and inflammation, little or no bleeding and a low probability of postoperative infection, as the laser sterilizes the irradiated area of the region to be treated.²⁸

The Erbium laser is the most recommended for fiberotomy (Er: YAG or ER, Cr: YSGG) because it allows fiber ligaments to re-establish a tissue pattern without inducing superficial necrosis. The diode laser is another alternative for this procedure; however, it can cause the tissue to detach, thus slowing healing.³⁴ So far, only animal studies using diode lasers for fiberotomy have been found during the retention period after orthodontic treatment.³⁰ It should be noted that this type of laser is the most widely used in clinical trials to evaluate the effectiveness of fiberotomy, taking into account that it is little absorbed by teeth and bones, making it a safer procedure due to the lower risk of hard tissue damage.³⁵

In 2017, Faramarz et al used the Nd:YAG laser for CSF. Their results showed that the location of gingival margin and alveolar bone crest remained unchanged after fiberotomy with the Nd:YAG laser during the orthodontic forced eruption procedure. It was also concluded that it can be used as a suitable method for fiberotomy as it produces little pain and allows good manipulation, allowing it to be used to the depth of the sulcus. Similarly, it shows low absorption in water and hard dental structures, but a high absorption in pigmented tissues such as hemoglobin, which makes it efficient in the hemostatic ablation of soft parts. This laser decreases fibroblasts and adhesion of periodontal fibers to the root surface during the healing process. Although this is known to be a disadvantage for routine periodontal treatment, it does benefit fiberotomy with fibers not adhering to dental surfaces.³⁶