INTRODUCTION

The presence of fixed appliances on the teeth of orthodontic patients may lead to plaque accumulation, which can hamper oral hygiene, cause a shift in the microbial ecosystem, and result in the colonization of periodontopathic bacteria and gingival enlargement.¹ Gingival enlargement impedes the maintenance of good oral hygiene and only the removal of the harmful substances can provide healing of the periodontal tissues.²

Although the first step to treat these periodontal issues is a nonsurgical treatment (ie, oral hygiene instructions, scaling, and prophylaxis), this method is not always successful, especially when motivation and self-care are compromised.³ Therefore, surgical approaches can be important tools to deal with periodontal issues. Conventional gingivectomy is performed with a scalpel and is considered the most common type of surgery.⁴ Despite its ease of use and accuracy, it does not provide good hemostasis, which can be critical when treating inflamed tissues.⁵ Surgical lasers, on the other hand, might be an alternative because they separate and coagulate simultaneously, providing better hemostasis, reducing the possibility of infection and preventing damage to hard tissues because their effect range is limited to soft tissues only.⁶

In addition to gingivectomy, different periodontal surgeries are routinely performed in orthodontic patients with fixed appliances, such as exposure of impacted teeth and circumferential supracrestal fiberotomy (CSF). CSF is a procedure used to reduce relapse of teeth after rotational movements and consists of transecting the supraalveolar (transseptal and free gingival) fibers of the periodontal ligament.⁷ Similar to gingivectomy, the exposure of impacted teeth and CSF can also be performed conventionally with a scalpel or with surgical lasers.

A previous systematic review⁸ already compared surgical periodontal procedures with scalpel and diode lasers; however, the review was not focused on orthodontic patients. Because orthodontic fixed appliances have already been proven to change the oral bacterial flora,⁹ new answers are yet to be found. Thus, the present systematic review aimed to assess more extensively the existing literature to answer the following focused question: Are clinical parameters using surgical laser for soft tissue procedures in orthodontic patients with fixed orthodontic appliances better than using conventional surgery with a scalpel?

MATERIALS AND METHODS

This review was conducted with the guidance of the Cochrane Handbook for Systematic Reviews of Interventions¹⁰ and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement.¹¹

Information Sources, Search Strategy, and Study Selection

Systematic searches were performed in the following electronic databases: MEDLINE/PubMed, Scopus/Elsevier, Web of Science Core Collection/Web of Science, The Cochrane Library/Wiley, LILACS/Virtual Health Library, BBO/Virtual Health Library and Embase/Elsevier. Searches on gray literature were performed in Google Scholar (screening the first 200 results), OpenGrey, and Portal de Periódicos da CAPES. The search strategy was developed for PubMed and then adapted for the other databases according to their syntax rules (Table 1). No restrictions on date or language were applied.

Table 1. Search Strategies Used in Search Procedures

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Table 1. Extended

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After the removal of duplicates, titles and abstracts were read to screen the records by two independent review members (EOA Vargas and KM Magalhães). In case of disagreement between the two reviewers, a consensus meeting was held where a third review member participated in the final decision (G Marañón-Vásquez). When the abstracts did not provide enough information, full texts were retrieved for analysis.

RESULTS

Study Selection

The flow chart of the search selection procedures, according to the PRISMA 2020 guideline,¹¹ is shown in Figure 1. Of the 796 articles initially retrieved, 494 remained after removing duplicates. A total 486 records were excluded after title and abstract screening, and eight articles were finally assessed for eligibility. Three articles were excluded after full-text reading (reasons for exclusion are shown in Figure 1). The alerts created in the databases revealed 30 new studies, none of which met the eligibility criteria. No extra references were added after contact with experts. In the end, five studies were included for qualitative synthesis.^4,17–20

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Study Characteristics

Three of the studies were performed in Iran,^17,19,20 one in Italy,⁴ and one in Nigeria.¹⁸ All studies were identified as randomized clinical trials.^4,17–20 Three studies evaluated gingivectomy,^4,17,18 two assessed CSF,^19,20 and one evaluated surgical exposure of impacted teeth, operculectomy, and frenectomy.¹⁸ The sample size ranged from 12 to 38 participants. Three studies used diode lasers,^4,17,18 one used a chromium-sensitized garnet-yttrium-scandium-gallium crystal (Er.Cr:YSGG) laser¹⁹ and another an erbium-doped yttrium aluminium garnet (Er:YAG) laser.²⁰ The following five different laser wavelengths were used: 810 nm⁴, 2780 nm,²⁰ 940 nm,¹⁷ 2940 nm,¹⁹ and 810 nm.¹⁸ Two surgical scalpel blades were used: 15C^4,17,18 and 11.^19,20 Three studies evaluated PPD and CCL.^4,19,20 One study evaluated GI,⁴ two studies assessed RR,^19,20 and four studies assessed the pain experienced by patients.^17–20 Two studies evaluated BA.^17,18 Evaluation periods ranged from immediately after surgery to 1, 2, and 6 months (Table 2).

Table 2. Summary of Characteristics of the Included Studies

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Table 2. Extended

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Table 2. Extended

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RoB Within Studies

The RoB assessment for randomized studies classified one of the studies as low risk.⁴ There was a consideration regarding the domain related to bias in measurement of the outcomes, as requested by the RoB 2 tool.¹³ Outcomes were assessed individually because, for some of them, calibration could have been previously performed (PPD, CCL, GI, and RR), but not for others (PA, BA). Hence, the study from Miresmæili et al.²⁰ was evaluated as having some concerns for PPD, CCL, and RR, and with high risk for PA (Pain assessment was judged as having high RoB). The study from Sobouti et al.¹⁷ was judged as having some concerns for PPD, CL, and RR, and with high risk for PA. The last two studies were judged as high risk.^18,19 The main factors that contributed to the RoB were the lack of clarity/quality in the randomization processes and the fact that outcome assessors were aware of the interventions received by the patients (Figure 2). The answers from all of the RoB assessments can be seen in the supplementary table.

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DISCUSSION

In orthodontics, the use of surgical lasers has increased because of advantages such as higher precision,²¹ coagulation of blood vessels,²² and less need for sutures.²³ This review assessed the existing literature on these issues using methodological rigor and well-established criteria.

Only three studies evaluated gingivectomy in orthodontic patients.^4,17,18 However, there was lack of standardization among the studies. The laser protocols were different as well as the outcomes assessed. Only Lione et al.⁴ evaluated PPD, CCL, and GI when performing gingivectomies. Sobouti et al.¹⁷ and Ize-Iyamu et al.¹⁸ evaluated PA and BA for this type of surgery. Ize-Iyamu et al.,¹⁸ on the other hand, performed different procedures rather than gingivectomy (ie, maxillary buccal frenectomies, surgical exposure of impacted teeth, and operculectomies). Because the results were not stratified according to the procedures for this last study, it was not possible to know the specific differences between laser and scalpel for each intervention or to use these data for a meta-analysis.

Only Lione et al.⁴ evaluated PPD, CCL, and GI when performing gingivectomies. The first two outcomes were evaluated in millimeters, whereas the latter was evaluated by a scale ranging from 0 to 3, where 0 was an absence of inflammation and 3 was severe inflammation. The study demonstrated that both laser and scalpel led to a substantial reduction of PPD and a substantial increase of CCL when compared with the baseline measurements, with no statistical differences between the groups. Laser-assisted gingivectomies seem promising for orthodontic patients considering that the results were similar to conventional surgeries and that the conventional treatment using scalpels can lead to clinical complications such as bleeding.²⁴ Although the study presented low RoB for the mentioned outcomes, because there was no other study for comparison of the results, more studies with methodological similarities are necessary. Also, larger samples are needed to obtain powerful results and to provide higher certainty of evidence.²⁵

Sobouti et al.¹⁷ and Ize-Iyamu et al.¹⁸ assessed PA and BA regarding gingivectomies. Unfortunately, the study by Ize-Iyamu et al.¹⁸ did not provide separate results for each procedure performed. For this reason, the results of this study were not combined with those of Sobouti et al.¹⁷ Pain was evaluated in all studies using a visual analog scale ranging from 0 to 10, where 0 was no pain and 10 was intolerable pain. Pain was assessed by the patients themselves. The fact that they were aware of the procedures performed may have interfered in how they reported symptoms and their intensity.²⁶ This characterizes the main methodological limitation of the studies for this outcome. This fact, added to the limited amount of data assessed, resulted in a very low certainty of evidence. Regarding BA, this outcome was evaluated on a scale from 0 to 4, where 0 was no bleeding and 4 was mortal bleeding. The outcome assessors were aware of the intervention received, and calibration could not be performed. In a similar way as PA, this methodological limitation, as well as the limited amount of data evaluated, led to a very low certainty of the evidence.

Although different procedures were pooled together by Ize-Iyamu et al.,¹⁸ the methodology to avoid bias when intervening in hard tissues (ie, exposing impacted teeth) was accurate. All patients initially underwent a previous surgical procedure to raise a flap and remove the overlying bone with a surgical bur. Then, an orthodontic bracket was bonded to the impacted tooth and the flap was replaced. Two months later, patients were randomly assigned into two groups and the exposures were performed methodologically similar between the groups, differing only by the scalpel or the laser used in the surgery. Therefore, both interventions could be compared. However, because the study did not provide separate results for each procedure performed, PA and BA could not be compared with other studies. The evidence related to the outcomes from this study was also very seriously affected by the RoB as well as by the limited amount of data evaluated. Despite the aforementioned limitations, the evidence showed that, regardless of the procedure performed and the laser protocol, there was a trend in favor of laser surgery in reducing pain and bleeding (with very low certainty of the evidence).

Two studies performed CSF in orthodontic patients.^19,20 This surgical procedure was evaluated with the same outcomes (PPD, CCL, RR, and PA) and for the same evaluation periods (baseline and 2 months) by both studies. Despite CSF being different from gingivectomy, the results for PPD and CCL also demonstrated that no statistical difference was found between laser and scalpel. RR was measured in degrees comparing the difference between the rotation of incisors immediately and 2 months after the CSF was performed. With low overall certainty of evidence, both studies^19,20 found no statistical difference between the interventions, but differences in the amount of RR was found between the studies. One reason for the discrepancy may have been the difference between sample sizes because Miresmæili et al.²⁰ performed a sample size calculation and Jahanbin et al.¹⁹ did not. Miresmæili et al. had 31 patients²⁰ and Jahanbin et al. had 12 patients.²⁵ Also, the use of different types of lasers and laser wavelengths could have been related to the difference between the results, which reinforces the need of standardization between studies. Regarding PA in CSF, Jahanbin et al.¹⁹ showed that there was less pain in the IG compared with the CG in contrast to Miresmæili et al.²⁰ The variations in the results of PA between the studies could also have been attributed to differences in sample sizes (Jahanbin et al.¹⁹ did not calculate the sample size and probably provided unpowered results) and the laser protocols used. In addition, because pain is subjective and was reported by patients themselves, there was a possibility of self-report bias and placebo effect by the use of a high-quality tool, that is, a surgical laser.²⁷ Mainly because of these limitations, the studies were judged as having high RoB. These facts, in addition to the inconsistency of the provided results as well as the limited amount of data assessed, resulted in a very low certainty of evidence.^19,20

Due to the small number of studies evaluating the same procedure, the same outcomes, and the same evaluation periods, no meta-analyses could be performed. In addition, there was methodological heterogeneity mainly related to protocols in the use of a laser. Different types of lasers, ranging from 810 to 2940 nm, were selected under the same category, which could have led to different results because different laser lengths are absorbed differently by different body tissues.²⁸ Future research should focus on performing similar types of surgery, using larger sample sizes, following patients for standardized periods, and using comparable laser protocols. In addition, regarding the RR for CSF, it is necessary to follow the participants for longer periods of evaluation because this is an outcome that can be expressed in the long term.¹⁹

CONCLUSIONS

• The existing literature on the subject is scarce, very heterogeneous, and has methodological limitations. Based on the available evidence, it is not possible to draw definitive conclusions about the beneficial effect of laser use in orthodontic patients.

• Researchers are encouraged to conduct new studies in the future, preferably randomized clinical trials, with standardized interventions and follow-up periods.