Electrical Stimulation Effect on Coronally Advanced Flap for the Treatment of Gingival Recession: Randomized Controlled Clinical Trial
Phase: NA
Conditions: Gingival Recession, Generalized
Sponsor: Universidade Estadual Paulista Júlio de Mesquita Filho

 
 
 
 
 
 
Electrical stimulation effect on coronally advanced flap 
for the treatment of single gingival recession: 
randomized controlled clinical trial 
 
UNESP – São Paulo State University. Dept. of Periodontology, College of 
Dentistry 
 
 
 
 
 
 
ClinicalTrial.org- NCT02987231 
São José dos Campos, São Paulo - Brazil 
August 15th, 2016 
 
 

 
STUDY PROTOCOL 
 
This investigation was a parallel, double-blind, randomized clinical trial. The 
study protocol (ClinicalTrial.org- NCT02987231) was approved by the Institutional 
Review Board at College of Dentistry – São José dos Campos, State University of São 
Paulo (1.679.369-UNESP). Each subject provided informed consent after a thorough 
explanation of the nature, risks, and benefits of the clinical investigation. 
Study Population 
Sixty patients from the Periodontology Clinic, UNESP—State University of São 
Paulo (São José dos Campos, Brazil), presenting 60 maxillary buccal gingival 
recessions in their canines and premolars were included in the study. The subjects were 
selected in the period between October 2016 and December 2017, according to the 
following eligibility criteria: 1) ≥18 years 2) periodontally and systemically healthy 3) 
FMPS and FMBS ≤20% 4) single Cairo’s class RT1 gingival recession (Cairo et al., 
2011) in the maxillary canines or premolars (≥3mmin depth) at the buccal 5) presence 
of identifiable CEJ 6) no previous periodontal surgery at the affected teeth. Study 
exclusion criteria: 1) systemic problems that would contraindicate the surgical 
procedure; 2) patients taking medications known to interfere with the wound healing 
process or that contraindicate the surgical procedure; 3) smokers and pregnant women; 
4) patients who underwent periodontal surgery in the area of interest; 5) patients 
undergoing orthodontic treatment. 
Before surgery, Patients received oral hygiene instructions (roll technique) with 
a soft-bristled toothbrush to correct wrong habits related to the etiology of the recession. 
All participants received a session of prophylaxis and scaling. The surgical treatment 
was performed only when patients achieved adequate plaque control (full-mouth plaque 
score ≤15%) 
Sample size 
The sample dimension was calculated using α = 0.05 and the power of 80%. For 
the standard deviation (SD), the value of 0.8 mm obtained in a previous paper (Jepsen et 
al. 2013). Thus, study was powered to detect a minimum clinically significant 
difference in root coverage of 0.8 mm between the test and control treatments for root 
coverage after 6 months. On the basis of these data, the minimum needed number of 

patients to be enrolled in this study resulted 28 for the test group (CAF) and 28 for the 
control group (CAF+ES). 
Randomization, allocation concealment, and blinding 
The randomization process was performed by an external person who did not 
participate in the study. Patients were assigned to one of the two treatment groups with 
the use of computer-generated randomization sequence. Allocation concealment was 
obtained using sealed coded opaque envelope containing the treatment to the specific 
subject. The sealed envelope containing the treatment assignment was opened 
immediately after the surgical procedure by the investigator responsible for the 
electrical stimulation protocol. The surgeon, patients and investigators who performed 
clinical measurements were blinded to procedures. 
Surgical procedure 
All surgical procedures were performed by a single operator (FLSN). With a 
blade 15c (Surgi Blade® - Miami, FL - USA) two horizontal incisions were made at the 
bases of the mesial and distal papillae of the tooth, towards the adjacent teeth, taking 
care not to touch the adjacent teeth. From the end of the incisions, two divergent 
relaxing incisions were performed vertically in the apical direction that surpassed the 
mucogingival line so that the flap had mobility for coronary traction. A sulcular incision 
was performed in order to unite the releasing incisions and a split-full-split thickness 
flap was raised beyond the mucogingival junction (MGJ) (de Sanctis & Zucchelli 2007). 
After the root planing procedures were performed, the epithelial layer was removed 
from the incised papillae exposing the connective tissue. Before the flap was positioned 
coronally, the region was washed copiously with physiological solution to remove the 
clot allowing intimate contact of the flap with the recipient bed. Sling sutures (5.0 
Vicryl™; Ethicon Inc, São José dos Campos, Brazil) were placed to stabilize the flap 2 
mm coronal to CEJ, followed by interrupted sutures to close the releasing incisions. 
Electric Stimulation Protocol 
The patients allocated in the CAF+ES group received the protocol for electrical 
stimulation. A unit consisting of a signal generator (Keysight Technologies., Inc., Santa 
Rosa-CA, USA), a power supply and circuit board, was assembled. Conductive 
electrodes for electrical current application were positioned on each side of the flap, at a 

mean distance of 3 mm from the relaxing incisions and an alternating current with 
intensity of 100 μA at 9 kHz, was distributed in order to traverse the operated region. 
Patients received the stimulus applications for 120 seconds, once a day for 5 
consecutive days. The electrical current was optimized through an oscilloscope 
(Keysight Technologies., Inc., Santa Rosa-CA, USA). All applications were performed 
by a single researcher involved in the study (CAS). Patients randomized to the CAF 
group received the simulation of the electrical stimulation process. 
Clinical Assessments 
Clinical parameters were evaluated at baseline, 3 and 6 months postoperatively 
as follows: 1) full-mouth visible plaque index (FMPI) (Ainamo & Bay 1975), and 
presence or absence of visible plaque accumulation at the site included in the study 
(plaque index [PI]); 2) full-mouth sulcus bleeding index (FMBI) (Muhlemann & Son 
1971), and presence or absence of bleeding on probing (BOP) at the site included in the 
study; 3) PD: measured in millimeters with a periodontal probe (XP23/UNC-15, Hu-
Friedy, Chicago, IL); 4) relative GR (RGR): distance from the gingival margin to the 
incisal border of the tooth; 5) RCAL: measured as PD+RGR; 6) GR: measured at the 
mid-buccal aspect of the tooth (both RGR and GR quantified using a caliper with a 
precision of 0.01mm and a pair of dividers); 7) keratinized tissue width (KTW); and 8) 
keratinized tissue thickness (KTT): measured at the midpoint location between the 
gingival margin and mucogingival junction as previously described (Fernandes-Dias et 
al., 2015). A masked and calibrated investigator (MMVM) carried out all clinical 
evaluations. The examiner calibration was performed for PD and RGR using Kappa 
statistic and intra-class correlation (k = 0.88 and ICC = 0.81, respectively). 
Esthetic evaluation 
To assess the final aesthetic outcome, two analyses were performed, one 
professional e one patient-centered. The professional evaluation was assessed using the 
Root Coverage Esthetic Score (RES) (Cairo et al. 2009). For this, two examiners 
performed the evaluations (JMB and IFM) 6 months after surgeries. The examiners 
presented previous experience in cosmetic dentistry, were blinded for the treatments and 
were previously calibrated (intra and inter-examiners K>0.8). Esthetic outcomes were 
also evaluated from the patient’s point of view, using a VAS scale pre- and 6 post-
postoperative. 

Patient-centered outcomes 
At the end of the first postoperative week, the patients completed a questionnaire 
about the occurrence of discomfort and postoperative pain. The pain was rated by the 
patient on a VAS scale of 0 to 10 (0 = no sensitivity and 10 = extreme pain). In addition, 
the patients were asked to report the number of analgesic pills they consumed that week. 
Dentin hypersensitivity was assessed by 5 s air blast from a triple syringe, applied to the 
exposed buccal cervical area. A visual analogue scale (VAS) scale (0 = no pain, 10 = 
extreme pain) was used to record DH related to stimulus. DH was recorded at baseline, 
3 and 6 months postoperatively. 
Sampling and immunological evaluation 
The samples were collected as previously described (Santamaria et al., 2013). 
Briefly, gingival crevicular fluid (GCF) was collected from the vestibular region of the 
site that received the CAF. Sampling was performed by introducing filter paper strips 
(Periopaper; Proflow Inc., Amityville, NY, USA) into sulci until mild resistance was 
felt, removed after 20 s, and collected fluid volume immediately determined by 
calibrated instrument (Periotron 8000; Ora Flow Inc., Plain View, NY, USA). The strips 
were placed in sterile tubes containing 300 ml of phosphate buffered saline (PBS) with 
0.05% Tween-2. Strips contaminated with visible blood were discarded. All GCF 
samples were stored immediately at -80° C. Samples were collected at baseline (before 
surgery), and 7, 14, 30, 60 and 90 days after surgery. 
Levels of Cito / chemokines were determined by a multiplex immunoassay. 
Aliquots of each GCF sample were tested using a commercial human kit (Millipore 
Corporation, Billerica, MA, USA), in order to evaluate levels of the following 
inflammatory markers: interleukin (IL)-1β, IL-6, IL-10, tumoral necrosis factor α 
(TNFα), macrophage inflammatory protein-1α (MIP-1α), and chemotactic protein for 
monocytes-1α (MCP-1α). In addition, matrix metalloproteinases (MMP)-2, MMP-9, 
tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2 and VEGF were also 
evaluated. Sample concentrations (antigens in gingival crevicular fluid samples) were 
estimated from the standard curve using standard kit proteins following manufacturer’s 
instructions and expressed as pg / mL. 
 

STATISTICAL ANALYSIS PLAN 
Descriptive statistics were performed using mean ± standard deviation (SD), and 
normality was tested using Shapiro-Wilk tests. The PD, RGR, CAL, KTT, KTW, and 
DH values and also inflammatory markers / growth factors were examined by two-way 
repeated measures ANOVA to evaluate the differences within and between groups, 
followed by a Tukey test for multiple comparisons when the Shapiro-Wilk p value was 
≥ 0.05. Data presenting Shapiro-Wilk p values < 0.05 were analyzed using Mann-
Whitney tests (for intergroup comparisons) and a Friedman test (for intragroup 
comparisons). Postoperative discomfort, patient’s esthetics measured through VAS and 
intergroup RES comparisons were analyzed by T-tests. The frequency of complete root 
coverage (CRC) was compared using χ2 tests. For all tests a significance level of 0.05 
was adopted.