1http://dx.doi.org/10.20396/bjos.v19i0.8658221 Volume 19 2020 e201669 Original Article 1 Department of Stomatology, Division of Periodontics, School of Dentistry, University of São Paulo (FO-USP), São Paulo, Brazil. Corresponding author: Claudio Mendes Pannuti Address: Av. Professor Lineu Prestes, 2227, ZIP Code 05508-000 – Department of Stomatology, Division of Periodontics, University of São Paulo – FO-USP, São Paulo, SP, Brazil. Telephone: +55 (11) 30917833. E-mail: pannuti@usp.br Received: May 24, 2019 Accepted: September 19, 2019 Effect of magnification on root coverage surgery: a systematic review Marcella Goetz Moro1, Maria Luisa Silveira Souto1, Emanuel Silva Rovai1, João Batista Cesar Neto1, Marinella Holzhausen1, Claudio Mendes Pannuti1,* Root coverage surgery can be performed in patients with gingival recession to cover the exposed root aiming to control hypersensitivity and promotes better aesthetic. Optical magnification has been proposed as a refinement in this surgical technique to increase root coverage. This approach may lead to enhanced soft tissue stability, less post-operative discomfort, better predictability and esthetic appearance. Aim: This systematic review aimed to evaluate the effectiveness of magnification on root coverage surgery when compared to procedures performed without magnification. Methods: Randomized controlled trials with a follow-up of at least 6 months that compared surgeries for root coverage performed under optic magnification versus conventional (macro) root coverage surgery were screened. The primary outcome was mean root coverage (mm) (MRC) and secondary outcomes were percentage of root coverage (PRC) and complete root coverage (CRC). Results: Of 569 papers relevant to this review, seven were included. Meta-analysis showed that the use of magnification may favor greater PRC (7.38%, 95% CI 3.66-11.09). Conclusion: Magnification can increase PRC in root coverage surgeries. More randomized trials with the use of magnification may be necessary to verify if this benefit is clinically relevant, in order to justify the use of this device. Keywords: Gingival recession. Microsurgery. Periodontitis. Review. 2 Moro et al. Introduction Gingival recession (GR) is the apical displacement of the gingival margin, which results in the exposure of the root surface1,2. It is a frequent condition, which affects a significant percentage of subjects and teeth3. It has been associated with older age, male gender4, smoking exposure5,6, higher education3,5,7,8, poor self-reported oral hygiene5,6,9,10, higher percentage of sites with gingivitis6, regular dental visits, history of periodontal treatment and presence of calculus3,5,7,8. Exposed root surfaces present an increased risk for caries, abrasion and erosion1,11,12. Furthermore, GR is related with hypersensitivity and poor esthetics, which has an impact on oral health-related quality of life13. Root coverage surgery can be performed in these patients, aiming to cover the exposed root14,15. The main objective of root cov- erage surgery is to achieve clinically relevant root coverage (RC). Several techniques have been proposed as root coverage procedures11,16,17, which result in correction of gingival deformities, position and/ or amount of keratinized tissue14,15. Currently, optical magnification has been proposed as a refinement in mucogin- gival surgical techniques, aiming to increase RC. Magnification of the operative field can be obtained by the use of loupes or microscope during the surgical pro- cedure to amplify visual acuity and enhance illumination. As a consequence, mag- nification may minimize surgical invasiveness, enables more precise incisions and suture co-adaptation of wound edges18. This approach may lead to enhanced soft tissue stability, less post-operative discomfort, better predictability and esthetic appearance2,19. Some clinical trials have observed that the use of optical magnification in root coverage procedures may enhance clinical outcomes and patient related out- comes, as aesthetic condition, when compared to conventional surgical proce- dures20-22, however, there is still lack of evidence in this field. A comprehensive evaluation, combining similar studies may contribute to understanding the impact of magnification on root coverage surgery. Therefore, the present systematic review and meta-analyses aims to evaluate whether the use of magnification pro- vides better clinical and aesthetic results when compared to conventional treat- ment in root coverage surgery. The following focused question was addressed: “In systemically healthy patients with Miller class I and/or II gingival recession, does magnification favor better clinical outcomes when compared to procedures without magnification?” Materials and methods The protocol of this systematic review (SR) was registered at the National Institute for Health Research PROSPERO, International Prospective Register of Systematic Reviews (http://www.crd.york.ac.uk/PROSPERO, registration number CRD42017064682). The review text was structured according to PRISMA’s guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses)23, Cochrane Handbook of System- atic Reviews of Interventions24 and Check Review checklist25. 3 Moro et al. Eligibility Criteria Inclusion Criteria Randomized controlled trials, with follow-up of at least 6 months, that compared sur- geries for root coverage performed under optic magnification versus conventional (macro) surgery in patients with Miller class I and/ or II gingival recessions were selected. Only studies that mentioned the use of microscope or loupe in the surgical procedure were included. Exclusion Criteria Trials that included patients with systemic disease (e.g., diabetes). Non-randomized trials, studies that did not have a control group without magnification, animal studies, in vitro studies, reviews and letters. Primary Outcome Mean root coverage (MRC), expressed in millimeters. Secondary Outcomes Percentage of root coverage (PRC), complete root coverage (CRC), keratinized tissue width (KTW) change, keratinized tissue thickness (KTT) change, clinical attachment level (CAL) change, probing pocket depth (PPD) change, aesthetic condition change, surgical operation time (min) and adverse effects. Information source and search strategy MEDLINE via PubMed, EMBASE and LILACS databases were used to search publications up to May 2019. MeSH terms and keywords were combined with Boolean operators (OR; AND) and used to search the databases. There was no restriction regarding language or publication year. Search strategies were: 1# root coverage OR gingival recession (MeSH terms) OR coronal advanced flap OR connective tissue graft OR periodontal plastic sur- gery OR mucogingival surgery AND; 2# microsurgery (MeSH terms) OR microscope OR microsurgical OR magnification OR loupe. In addition, reference lists of the selected stud- ies were hand-searched, and unpublished studies were searched at Open Grey. Study Selection Study selection was completed in two phases, as follows: 1) titles and abstracts; 2) full text screening. In the first phase, two reviewers (M.G.M. and M.L.S.S.) inde- pendently screened titles and abstracts. In the second phase, the same reviewers independently read the full text of the selected articles. In both phases, any dis- agreement was resolved by a third reviewer (C.M.P.). Data extraction and validity assessment were performed for publications that met the inclusion criteria and rea- sons for excluding publications were recorded. Data collection Two reviewers (M.G.M. and M.L.S.S.) collected data from the selected articles using extraction forms. Any disagreements in the data extraction were discussed with a 4 Moro et al. third reviewer (C.M.P.). Also, if needed, the authors of the included studies were con- tacted to elucidate questions or provide missing data. The following data were recorded from the eligible studies: 1) citation, 2) country of the study, 3) characteristics of trial participants (age, gender and other trial´s eligibility criteria), 4) Miller’s classification of the recession defect26, 5) length of follow-up, 6) intervention’s characteristics (type of surgery, type of microscope/ loupe, magnifica- tion and microsurgical instruments), 7) sample size, 8) outcome measures, 9) conclu- sions, and 10) financial support and conflict of interest. Risk of bias of the included studies Risk of bias was ascertained according to the Cochrane Collaboration’s Tool for Assessing Risk of Bias. Two reviewers (M.G.M. and M.L.S.S.) independently evalu- ated quality of randomization and allocation concealment (selection bias); complete- ness of follow-up period/ incomplete outcome data (attrition bias); selective reporting (reporting bias); blinding of examiners (detection bias) and other forms of bias. Perfor- mance bias was not evaluated since it is not possible to mask patients and operators in studies that use microscopes or loupes. Each domain was classified as adequate (+), inadequate (-) or unclear (?). Overall risk of bias was categorized as: 1) low risk of bias if all criteria were met; 2) unclear risk of bias if one or more criteria were partly met; or 3) high risk of bias if one or more criteria were not met. Any disagreement was solved by a third investigator (C.M.P.). Quality of evidence (GRADE) GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) guidelines were used to assess the strength of evidence across RCTs for each out- come. The quality of evidence was classified into four categories: high quality, moder- ate quality, low quality, and very low quality, based on risk of bias, consistency, direct- ness and precision27. Summary measures and Synthesis of results Summary measures were calculated as difference in means for MRC and PRC, gain of KTW and CAL change, and as risk ratio for CRC, using random-effects models. All meta-analyses were conducted with a software package (Review Manager Software, version 5.3, The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). Moreover, heterogeneity among the included studies was assessed with Cochran Q statistic and I2 28. RESULTS A total of 569 potentially relevant papers were identified. After screening of titles and abstracts, 558 were excluded, leaving 11 articles. After complete reading of full text, 4 papers were considered not eligible for inclusion. At the end of the process, 7 papers were included in the review, as shown in the Flowchart (Figure 1). 5 Moro et al. Included studies Initially, 135 subjects with gingival recession were enrolled, and 128 (94.8%) com- pleted the follow up period. The main characteristics of the included studies are shown in Table 1. The age of the included patients ranged from 18 to 67 years old, and most of them were female. When Miller’s classification of the recession defect was analyzed, Class I was predominant. A total of 255 Miller class I and II gingival reces- sions were treated. Four studies used a split mouth design20,22,29,30, and the other three used parallel groups19,21,31. The follow-up period of the trials were 629,30, 1219,20,22,31 and 24 months21. Seven participants drop out the respective studies20,29 either because of relocation or refusal to complete the research. Most of the selected studies excluded smokers20-22,29,31. However, two papers did not mention the smoking habits of the included participants19,30. Risk of bias Two studies were considered of low bias risk22,31 and the other five were considered of unclear risk of bias (Figure 2)19-21,29,30. Records identified through database searching (n = 569) Additional records identified through other sources (n = 0) Records after duplicates removed (n = 569) Records screened (n = 569) Records excluded (n = 558) Full-text articles assessed for eligibility (n = 11) Studies included in qualitative synthesis (n = 07) Studies included in quantitative synthesis (meta-analysis) (n = 07) Studies excluded, with reasons (n = 0) Agarwal et al. (2016): Comparison between microsurgical techniques. Francetti et al. (2004): Surgical technique around implant. Thankkappan et al. (2015): Comparison between microsurgical techniques. Andrade et al. (2010): Miller class III gingival recessions Id en ti fi ca ti on S cr ee ni ng El ig ib ili ty In cl ud ed Full-text articles excluded, with reasons (n = 04) Figure 1. Flowchart. 6 Moro et al. Table 1. Characteristics of the studies. Study/ Country Study design Follow-up Sample Size (baseline) Participants Recession areas (Miller’s classification)/ number of recessions Source of Funding Azaripour et al., 2016/ Germany Parallel RCT 12 months N= 40 (15 Male and 25 Female) Age Range: 19-64 years (38.6 ± 12.8 years) Test group: N baseline = 15 N end of trial = 15 Control group: N baseline = 15 N end of trial = 15 At least one Miller class I or II buccal gingival recession defect ≥ 1 and < 6 mm in depth. N = 71 (42 test; 29 control) Department of Operative Dentistry and Periodontology of the University Medical Central, Mainz. Bittencourt et al., 2012/ Brazil Split- mouth RCT 12 months N= 24 (13 Male and 11 Female) Age Range: 18-55 years (34 years) Test group: N baseline = 24 N end of trial = 24 Control group: N baseline = 24 N end of trial = 24 Presence of bilateral Miller Class I or II gingival recessions (> 2 mm) in maxillary canines or premolars. N = 48 (24 test; 24 control) Research Funding Agency of Bahia State, Brazil. Burkhardt et al., 2005/ Switzerland Split- mouth RCT 12 months N= 10 (4 Male and 6 Female) Mean Age: 32-44 years (mean not mentioned) Test group: N baseline = 10 N end of trial = 8 Control group: N baseline = 10 N end of trial = 8 Presence of bilateral canine root denudations of Class I or II. N = 20 (10 test; 10 control) No Francetti et al., 2005/ Italy Parallel RCT 12 months N= 24 (Male and Female not mentioned) Age: not mentioned Test group: N baseline = 12 N end of trial = 12 Control group: N baseline = 12 N end of trial = 12 Buccal recession at least 2 mm deep; no loss of interdental bone or soft tissue (Class I or II Miller’s). N = 24 (12 test; 12 control) No Jindal et al., 2015/ India Split- mouth RCT 6 months N= 7 (6 Male and 1 Female) Mean Age: 18-67 years (mean not mentioned) Test group: N baseline = 7 N end of trial = 7 Control group: N baseline = 7 N end of trial = 7 Bilateral isolated or multiple Miller’s Class I or Class II gingival recession ≥2 mm when measured from cement enamel junction (CEJ) on anterior teeth or premolar. N = 30 (15 test; 15 control) No Nizam et al., 2015/ Turkey Parallel RCT 24 months N= 24 (11 Male and 13 Female) Age Range: 19-41 years (mean not mentioned) Test group: N baseline = 15 N end of trial = 13 Control group: N baseline = 15 N end of trial = 12 Presence of Miller class I or class II gingival recession >2 mm in at least one canine or premolar tooth. N = 42 (21 test; 21 control) No Pandey and Mehta, 2013/ India Split- mouth RCT 6 months N= 10 (Male and Female not mentioned) Age Range: 20-45 years (mean not mentioned) Test group: N baseline = 10 N end of trial = 10 Control group: N baseline = 10 N end of trial = 10 At least two sites of Miller’s class I or class II gingival recession labially in different quadrants with thick and wide interproximal papilla not smaller than the recession defect. N = 20 (10 test; 10 control) No 7 Moro et al. In four studies, treatment was randomly assigned by coin toss20-22,29 and two studies used computer-generated random sequence19,31. One publication did not report how random sequence was generated30. Four studies reported that allo- cation concealment was made properly21,22,29,31 and three studies did not report this information19,20,30. Effects of interventions Individual outcomes of studies The individual outcomes of studies are present in Table 2. Five of the included trials used MRC as primary outcome19,21,22,30,31. As secondary outcomes, six trials used PRC and CRC19-22,29,31. Although Pandey and Mehta30 (2013) did not use PRC and CRC as outcome, they used MRC, CAL gain and KTT (in mm). The use of magnification pro- moted significantly greater MRC in Bittencourt et al.22 (2012) and Nizam et al.21 (2015) studies. These two trials and the study of Burkhardt and Lang20 (2005) showed that Figure 2. Risk of bias. + ++++++ + ????? ? ? ? ? ? ? ? ? ??? ? ? ? ++++++ + ++ + + +++ +++ +++++ Azaripour et al. 2016 Bittencourt et al. 2012 Burkhardt et al. 2005 Francetti et al. 2005 Jindal et al. 2010 Nizam et al. 2015 Pandey & Mehta et al. 2013 R an do m s eq ue nc e ge ne ra tio n (s el ec tio n bi as ) A llo ca tio n co nc ea lm en t ( se le ct io n bi as ) B lin di ng o f o ut co m e as se ss m en t ( de te ct io n bi as ) In co m pl et e ou tc om e da ta (a tt rit io n bi as ) Se le ct iv e re po rt in g (r ep or tin g bi as ) Sa m pl e si ze c al cu la tio n O ve ra ll ris k of b ia s 8 Moro et al. Ta bl e 2. P ar tic ip an ts , I nt er ve nt io ns , o ut co m es a nd re su lts . S tu dy In te rv en tio ns M ic ro su rg ic al eq ui pm en t A es th et ic c on di tio n P R C / M C R m m C R C si te s/ % C A L m m K T W m m A za rip ou r e t a l., 20 16 Te st g ro up : M M T T + C TG C on tr ol g ro up : C A F + C TG Ze is s m ic ro sc op e “P IC O ”, se tt in g va rie s be tw ee n 0. 4 to 0 .6 (x 4- 7 m ag ni fic at io n) , m ic ro su rg ic al in st ru m en ts . P at ie nt ’s o pi ni on : s at is fa ct or y (t es t a nd c on tr ol ); P ro fe ss io na l’s o pi ni on (R ES ): Te st : 9 .2 ± 1 .1 C on tr ol : 9 .2 ±1 .3 Te st : 9 7. 3 ± 7. 6% / 2. 1 ± 1. 1 C on tro l: 98 .3 ± 9. 2% / 2. 3 ± 1. 2 Te st : 3 7/ 88 .1 % C on tro l: 28 / 96 .6 % N ot re po rt ed Te st : 0. 48 ± 0 .6 C on tro l: 0. 36 ± 0. 6 Bi tte nc ou rt e t a l., 20 12 Te st g ro up : t ec hn iq ue pr op os ed by T ib be tt s an d Sh an el ec a nd m od ifi ed b y C am po s et a l. + C TG (m ic ro su rg er y) C on tr ol g ro up : t ec hn iq ue pr op os ed by T ib be tt s an d Sh an el ec a nd m od ifi ed b y C am po s et a l. + C TG (c on ve nt io na l t ec hn iq ue ) M ic ro sc op e at x 8 to x1 2 m ag ni fic at io n (S M P lu s, O pt o El et rô ni ca , Sã o P au lo , S P, B ra zi l); m ic ro su rg ic al in st ru m en ts . P at ie nt ’s o pi ni on : T es t: 10 0% C on tr ol : 7 9. 1% P ro fe ss io na l’s o pi ni on : n ot re po rt ed Te st : 9 8% */ 2 .4 6 ± 0. 38 * C on tro l: 88 .3 % / 2. 24 ± 0 .6 4 Te st : 2 1/ 87 .5 % * C on tro l: 14 / 58 .3 % Te st : 1. 96 ± 0 .8 2 C on tro l: 1. 99 ± 0. 69 Te st : 1. 51 ± 1 .0 1 C on tro l: 1. 37 ± 1, 18 B ur kh ar dt e t a l., 20 05 Te st g ro up : m ic ro su rg er y C on tr ol g ro up : m ac ro su rg er y Th e su rg ic al p ro ce du re w as pe rf or m ed a cc or di ng to th e te ch ni qu e de sc rib ed b y H ar ris (1 99 2) u si ng fr ee c on ne ct iv e tis su e gr af ts c ov er ed b y a do ub le -p ed ic le p ap ill a fla p. O P M I® P ro m ag is a t 15 m ag ni fic at io n (C ar l Ze is s) , m ic ro su rg ic al in st ru m en ts . N ot re po rt ed Te st : 9 8. 0 ± 3. 4% * C on tro l: 89 .9 ± 8. 5% Te st : 5 / 62 .5 % * C on tro l: 2/ 25 % N ot re po rt ed N ot re po rt ed Fr an ce tt i e t a l., 20 05 Te st g ro up : 6 C A F + C TG , 1 C A F + G TR , 4 C A F + C TG + EM D , 1 s em ilu na r fl ap (m ic ro su rg er y) C on tr ol g ro up : 9 C A F + C TG , 1 C A F + G TR , 2 C A F (m ac ro su rg er y) Th e ty pe o f s ur gi ca l t ec hn iq ue w as c ho se n in re la tio n to th e an at om ic fe at ur es o f t he s ite . Th e m ic ro sc op e us ed ha d a fib er -o pt ic ill um in at io n sy st em , an d th e m ag ni fic at io n va rie d be tw ee n 5x a nd 30 x (C ar l Z ei ss O m ni P ro 55 ), m ic ro su rg ic al in st ru m en ts . P at ie nt ’s o pi ni on : n ot re po rt ed P ro fe ss io na l’s o pi ni on : q ua lit at iv e (s ca rr in g, g in gi va l m ar gi n, a nd pa pi lla e ap pe ar an ce ). Te st : b et te r r es ul ts o f s ca rr in g an d gi ng iv al m ar gi n* Te st : 8 6% / 2. 67 ± 0. 87 C on tro l: 78 % / 2. 63 ± 0 .9 1 Te st : 5 8. 3% C on tro l: 33 .3 % Te st : 2. 63 ± 0 .8 6 C on tro l: 2. 38 ± 1. 15 Te st : 1. 79 ± 0 .6 9 C on tro l: 1. 7 ± 1. 51 co nt in ue 9 Moro et al. S tu dy In te rv en tio ns M ic ro su rg ic al eq ui pm en t A es th et ic c on di tio n P R C / M C R m m C R C si te s/ % C A L m m K T W m m Ji nd al et a l., 2 01 5 Te st g ro up : m ic ro su rg er y C o nt ro l g ro up : m ac ro su rg er y A p ar ti al t hi ck ne ss f la p, w it h tw o v er ti ca l i nc is io ns pl ac ed a t le as t o ne -h al f to o ne t o o th w id er m es io - di st al ly t ha n th e ar ea o f gi ng iv al r ec es si o n an d pl ac em en t o f co nn ec ti ve ti ss ue g ra ft , r et ri ev ed f ro m pa la te t o r ec ip ie nt w as d o ne ac co rd in g to t he L an ge r an d La ng er t ec hn iq ue . Su rg ic al m ic ro sc op e (E nf or te ) a t a m ag ni fic at io n of 1 0x , 6 -0 vi cr yl s ut ur es . P at ie nt ’s o pi ni on : n ot re po rt ed P ro fe ss io na l’s o pi ni on : q ua lit at iv e (s ca rr in g, g in gi va l m ar gi n, a nd pa pi lla e ap pe ar an ce ). B et te r e st he tic o ut co m es in te st , w he n co m pa re d to c on tr ol (n o st at is tic al ly s ig ni fic an t d iff er en ce ). Te st : 6 7. 58 % C on tro l: 61 .7 8% Te st : 4 / 26 .6 7% C on tro l: 3/ 20 % Te st : 3 .1 3 C on tro l: 2. 43 N ot re po rt ed N iz am et a l., 2 01 5 Te st g ro up : C P F + C TG (m ic ro su rg er y) C on tr ol g ro up : C P F + C TG (m ac ro su rg er y) M ic ro sc op e un de r x 3. 5 m ag ni fic at io n, u si ng th e eq ui pm en t d es ig ne d fo r m ic ro su rg er y (b la de s, ne ed le h ol de r, sc is so rs , an d tis su e fo rc ep s) . P at ie nt ’s o pi ni on ( V A S s ca le ): T he a es th et ic s co re s of t he in te rv en ti on s w er e si gn if ic an tl y an d si m ila rl y im pr ov ed d ur in g al l ev al ua ti on t im e po in ts c om pa re d w it h ba se lin e (s co re s be tw ee n 8 an d 9) . P ro fe ss io na l’s o pi ni on : n ot re po rt ed . Te st : 9 5. 82 ± 8. 41 % */ 3 .6 2 ± 0. 85 * C on tro l: 83 .4 6 ± 16 .2 1% / 2. 96 ± 0. 69 Te st : 1 5 C on tro l: 9 Te st : 3 .4 4 ± 0. 97 * C on tro l: 2. 80 ± 0. 74 Te st : 2 .2 4 ± 1. 17 C on tro l: 2. 09 ± 0. 84 P an de y an d M eh ta , 2 01 3 Te st g ro up : f re e ro ta te d pa pi lla a ut og ra ft + C A F (m ic ro su rg er y) C on tr ol g ro up : f re e ro ta te d pa pi lla a ut og ra ft + C A F (m ac ro su rg er y) M ic ro sc op e (S er w el l C om pa ny , C he nn ai ) un de r x 10 m ag ni fic at io n, m ic ro su rg ic al in st ru m en ts . N ot re po rt ed Te st : 2 .0 5 C on tro l: 2. 13 N ot re po rt ed Te st : 0 .7 C on tro l: 0. 5 N ot re po rt ed K T W : k er at in iz ed ti ss ue w id th ; C P F: c or on al ly p os iti on ed fl ap ; C R C : C om pl et e ro ot c ov er ag e; M R C : M ea n ro ot c ov er ag e; E M D : e na m el m at rix d er iv at e; C A F: c or on al ly a dv an ce d fla p; M M T T: m od ifi ed m ic ro su rg ic al tu nn el te ch ni qu e; C TG : s ub ep ith el ia l c on ne ct iv e tis su e gr af t; R ES : R oo t c ov er ag e ae st he tic s co re ; G TR : g ui de d tis su e re ge ne ra tio n; V A S: v is ua l a na lo g sc al e; C A L: c lin ic al a tt ac hm en t l ev el ; L M C A F: la te ra lly m ov ed c or on al ly a dv an ce d fla p. co nt in ua tio n 10 Moro et al. the intervention with magnification promoted significantly more PRC than conven- tional surgery. In addition, more sites with CRC were found in the test group in the studies of Bittencourt et al.22 (2012) and Burkhardt and Lang20 (2005). Moreover, when CAL gain was analyzed, two papers were not included20,31. Just one study found out that magnification promotes significantly more CAL gain when compared to control group21. On the other hand, four papers analyzed KTW change and none of them showed significant differences between groups19,21,22,31. Four stud- ies evaluated PPD change and no differences were found between control and test groups19,21,22,31. One study evaluated KTT change, and no differences were detected between groups22. Two trials observed that the length of surgery was greater using microscopes, when compared to conventional technique (72 ± 8 min versus 51 ± 5 min20; 73 ± 12 min versus 55 ± 8 min)21 and one study did not found differences between groups (test: 60 min versus control: 54 min)22. Divergences among studies were observed as regards to aesthetic condition change. As regards professional`s opinion, in one parallel study, using the root cov- erage aesthetic score (RES), both conventional surgery and surgery under magnifi- cation were related with acceptable esthetic (Test: 9.2 ± 1.1/ Control: 9.2 ± 1.3)31. In another split-mouth study, the use of magnification resulted in 100% aesthetic sat- isfaction, while conventional surgery was associated with 79.1% satisfaction22. The parallel study of Nizam et al.21 (2015) also used visual analog score (VAS) to obtain patient’s opinion. The aesthetic scores of conventional surgeries and the technique with magnification were significantly improved, with no differences between groups. Two trials used a qualitative scale to obtain professional’s opinion using pictures of treated sites, as follows: scarring, gingival margin, and papillae appearance19,29. Although Francetti et al.19 (2005) found better results for scarring and gingival mar- gin in the magnification group, Jindal et al.29 (2015) observed no difference between groups regarding esthetic outcomes. Pooled outcomes Pooled estimates of MRC (in mm) were available in 5 studies19,21,22,30,31 and showed no difference between the use of magnification and conventional treatment (mean differ- ence = 0.20 mm, 95% CI -0.10-0.50; I2 = 35%, p = 0.18; low quality) (Figure 3 and Table 3). Six studies were summarized in the meta-analysis of PRC19-22,29,31, and indicated that magnification resulted in greater PRC than conventional technique (mean difference = 7.38%, 95% CI 3.66-11.09; I2 = 0%, p < 0.0001; low quality) (Figure 3 and Table 3). CRC data was available for 6 studies19-22,29,31. Results indicated that magnification did not increased the chance of CRC (RR = 1.35, 95% CI 0.94-1.92; I2 = 62%, p = 0.10; very low quality) (Figure 3 and Table 3). Meta-analysis of CAL gain19,21,22,30 showed no difference between the use of microscope and conventional technique (mean difference = 0.25 mm, 95% CI -0.11-0.61; I2 = 21%, p = 0.17; low quality) (Supplementary Material 1 and Table 3). Moreover, similar results were found when pooled outcomes were calculated in 5 stud- ies that evaluated KTW (mean difference: 0.08 mm, 95% CI -0.10-0.27; I2 = 0%, p = 0.39; very low quality) (Supplementary Material 1 and Table 3)19,21,22,30,31. 11 Moro et al. Meta-analysis for PPD and KTT were not conducted since few studies presented these variables. Adverse effects One study reported absence of complications associated with conventional surgery and the use of magnification19. One study reported that in the conventional technique groups, three subjects had dentin hypersensitivity and 10 had postoperative pain, Figure 3. Forest plot of random effects meta-analysis evaluating MRC, PRC and CRC on magnification. 12 Moro et al. Ta bl e 3. G R A D E su m m ar y of fi nd in gs ta bl e fo r r oo t c ov er ag e su rg er y un de r m ag ni fic at io n ve rs us c on ve nt io na l r oo t c ov er ag e su rg er y. C er ta in ty a ss es sm en t № o f pa tie nt s Ef fe ct Q ua lit y of ev id en ce Im po rt an ce № o f st ud ie s S tu dy de si gn R is k of bi as In co ns is te nc y In di re ct ne ss Im pr ec is io n O th er co ns id er at io ns R oo t c ov er ag e su rg er y w ith m ag ni fic at io n C om ve nt io na l ro ot c ov er ag e su rg er y R el at iv e (9 5% C I) A bs ol ut e (9 5% C I) M ea n ro ot c ov er ag e (f ol lo w u p: ra ng e 6 m on th s to 2 4 m on th s; a ss es se d w ith : m m ; S ca le fr om : 2 .0 to 4 .4 ) 5 Ra nd om iz ed tr ia ls se rio us a no t s er io us no t s er io us se rio us b no ne 11 4 11 3 - m ea n 0. 26 m m m or e (0 .0 7 m or e to 0 .4 6 m or e) lo w C R IT IC A L P er ce nt ag e of ro ot c ov er ag e (f ol lo w u p: ra ng e 6 m on th s to 2 4 m on th s; a ss es se d w ith : % ; S ca le fr om : 4 to 2 3) 6 Ra nd om iz ed tr ia ls se rio us a no t s er io us no t s er io us se rio us b no ne 11 9 11 8 - m ea n 7. 41 h ig he r (4 .2 6 hi gh er to 1 0. 57 hi gh er ) lo w C R IT IC A L C om pl et e ro ot c ov er ag e (f ol lo w u p: ra ng e 6 m on th s to 2 4 m on th s; a ss es se d w ith : N um be r o f e ve nt s; S ca le fr om : 2 to 3 7) 6 Ra nd om iz ed tr ia ls se rio us a se rio us c no t s er io us se rio us b no ne 11 9 11 8 - m ea n 1. 35 m or e (1 .0 4 m or e to 1 .7 5 m or e) V er y lo w C R IT IC A L K er at in iz ed ti ss ue w id th (f ol lo w u p: ra ng e 6 m on th s to 2 4 m on th s; a ss es se d w ith : m m ; S ca le fr om : 0 .0 to 5 .0 ) 4 Ra nd om iz ed tr ia ls se rio us a no t s er io us no t s er io us ve ry se rio us b no ne 11 4 11 3 - m ea n 0. 15 m m m or e (0 .0 2 fe w er to 0 .3 2 m or e) V er y lo w IM P O RT A N T C lin ic al a tt ac hm en t l ev el (f ol lo w u p: ra ng e 6 m on th s to 2 4 m on th s; a ss es se d w ith : m m ; S ca le fr om : 0 .5 to 4 .3 ) 5 Ra nd om iz ed tr ia ls se rio us a no t s er io us no t s er io us se rio us b no ne 99 98 - m ea n 0. 33 m m m or e (0 .1 m or e to 0 .5 7 m or e) lo w IM P O RT A N T A ut ho r( s) : M or o M G , S ou to M LS , R ov ai E S, C es ar N et o JB , H ol zh au se n M , P an nu ti C M . Q ue st io n: R oo t c ov er ag e su rg er y un de r m ag ni fic at io n co m pa re d to c on ve nt io na l r oo t c ov er ag e su rg er y in h ea lth y pa tie nt s w ith g in gi va l r ec es si on . Se tt in g: B ra zi l, G er m an y, S w itz er la nd , I ta ly , I nd ia , T ur ke y B ib lio gr ap hy : A za rip ou r e t a l. (2 01 6) ; B itt en co ur t e t a l. (2 01 2) ; B ur kh ar dt e t a l. (2 00 5) ; F ra nc et ti et a l. (2 00 5) ; J in da l e t a l. (2 01 5) ; N iz am e t a l. (2 01 5) ; P an de y an d M eh ta (2 01 3) . C I: C on fid en ce in te rv al Ex pl an at io ns a. A cc or di ng to th e ta bl e of ri sk o f b ia s, th e m os t o f s tu di es w er e cl as si fie d as u nc le ar ri sk o f b ia s du e to th e fa ils o f r an do m iz at io n an d al lo ca tio n, b lin d of e xa m in er s, a s w el l, sa m pl e si ze c al cu la tio n. b. T he s am pl e si ze o f s tu di es is s m al l a nd ju st tw o st ud ie s re po rt ed h ow it w as c al cu la te d. A ls o, th e co nfi de nc e in te rv al d oe s no t r ul e ou t a n ul l e ff ec t o r h ar m . c. T he m od er at e he te ro ge ne ity c ou ld b e ex pl ai ne d by th e us e of d iff er en t p er io do nt al s ur gi ca l t ec hn iq ue s an d re ga rd in g th e ra ng e of m ag ni fic at io n. 13 Moro et al. while 10 participants had postoperative pain in the magnification group22. Three trials did not report information about the presence of postoperative complications20,29,31. In another study, one subject in each group had postoperative hemorrhage and one participant in the test group had partial necrosis and swelling in the donor area21. Moreover, one trial showed that less subjects in test group (20%) had postoperative pain when compared to control group (60%)30. DISCUSSION The findings of this review suggest that magnification has a controversial influence on clinical outcomes in root coverage procedures. Surgeries performed under magni- fication may result in higher PRC than the ones performed without magnification. On the other hand, when analyzing the other outcomes, including the primary outcome, magnification did not promote additional benefit. Magnification was associated with approximately 7% more root coverage than the conventional technique. Although this percentage was considered statistically significant, the clinical relevance of this improvement must be discussed. The clinician should analyses if it is worth invest on magnification for gain more 7% of root coverage than conventional technique. Mod- erate heterogeneity between studies was detected in meta-analysis of CRC (62%), whereas pooled estimates of MRC and PRC showed low heterogeneity (35% and 0%, respectively), what may reinforce the reliability of such findings. Supplementary Material 1. Forest plot of random effects meta-analysis evaluating CAL gain and KTW change on magnification. 14 Moro et al. The rationale use of magnification in periodontal surgery involves a combination of practical considerations associated with scientific evidences that indicates, in some clinical situations, that magnification may be an advantage for both the practitioner and the patient. However, it is difficult to directly compare the available devices and to identify which magnification yielded the best results. Loupe was defined as a dou- ble monocular telescope with converging lenses side by side to focus on the opera- tive field. The range of magnification varies between 1.5 and 6 x32. The microscope provides a greater range of magnification (4-45 x). It incorporates an optical system coated with achromatic lenses and has a high optical resolution due to the enhanced depth of focus and field of view33. Microscope allows the adjustment of magnification according to the preference of the user in each step of the procedure. The microscope magnification of the trials selected for this review ranged from 3 to 30 x. Further, the values of magnification also varied within the same study. Azaripour et al.31 (2016) used a magnification that varied between 4 and 7x, and the magnification of Francetti et al.19 (2005) and Bitten- court et al.22 (2012) studies varied between 5 and 30 x; and 8 and 12 x, respectively. The studies of Burkhardt and Lang20 (2005), Jindal et al.29 (2015), Nizam et al.21 (2015), and Pandey and Mehta30 (2013) applied just one value of magnification (15 x, 10 x, 3.5 x and 10 x, respectively). The use of different surgical techniques also difficult comparisons. The majority of the studies used coronally positioned flap (CPF) in association with subepithelial connec- tive tissue graft (CTG)21,22,29. Other studies used double-pedicle papilla flap20, and free rotated papilla autograft + coronally advanced flap (CAF)30. Azaripour et al.31 (2016) compared different techniques (modified microsurgical tunnel technique + CTG ver- sus CPF + CTG), while Francetti et al.19 (2005) used different techniques, according to the patient’s need. Azaripour et al.31 (2016) was the only study that included upper first molars. The others included incisors, canines and premolars (maxilla and mandible)29; anterior area from maxilla and mandible19; canines and premolars from maxilla21,22; or upper canines20. Despite the present interesting findings, it should be considered that RC may vary according to tooth types due to the anatomic characteristics as recession width, frenum attachments and lip muscles34,35. Another point is about the operators. The use of magnification is associated with a well-trained and experience operator, while the conventional surgery can be performed by a less trained operator. The use of magnification is associated with an additional financial investment, training time and potential longer surgical time36,37. These factors induced the operator to get better and promoted more precise surgeries. The precision and refinement promoted by magnification may result in better final visual analyze38. Esthetic evaluation was conducted by Francetti et al.19 (2005) and Bittencourt et al.22 (2012) that found superior results for surgery with magnification. Two studies followed patients for 6 months29,30, the majority of the investigations fol- lowed the subjects for 12 months19,20,22,31 and Nizam et al.21 monitored the subjects for 24 months. Although some studies claim that the longer the follow-up time, the changes are more stable39, other studies have reported that results obtained after 6 15 Moro et al. months are stable over time up to 12 months40,41 or even after 3 years of follow-up42. Tissue stability is also associated with other aspects, including surgical technique, tissue thickness and mainly oral hygiene habits of the patients. Within the limits of our knowledge, this is the second systematic review investigating the influence of magnification on root coverage procedures and some important differ- ences have to be highlighted. While the present review included seven trials, the previous review was limited to the inclusion of four studies2. This difference could be explained due to the publication of recent papers addressing magnification and also, no restric- tions for surgical technique. Another difference is that meta-analysis in the Kang et al.2 (2015) review included only two studies that used CTG in the surgical procedure20,22. Despite our interesting findings, some limitations must be addressed. Five studies were classified as unclear risk of bias19-21,29,30. Studies that present unclear or high risk of bias tend to overestimate the effect of treatment and decrease the reliability of the tri- als’ conclusions. Moreover, according to GRADE, three outcomes (MRC, PRC and CAL change) were related to low quality and two outcomes (CRC and KTW change) were related to very low quality, which indicated that further research is recommended to confirm whether the estimates are close to real values. Still, when patient related outcomes are analyzed, the use of microscope did not inter- fere positively on discomfort, postoperative pain and esthetic evaluation22,31. In this sense, well-conducted studies are needed, in order to focus not only in clinical aspects, but also evaluating the perspective of the practitioner. Data regarding physical lesions caused by work, fatigue after working hours and frequency of pain in neck and column could bring interesting information for the field. 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