Comparison of Two Different Low-level Laser Intensity Protocols on the Healing of Palatal Wounds

Comparison of Two Different Low-level Laser Intensity Protocols on the Healing of Palatal Wounds After Connective Tissue Graft Removal: Randomized Clinical Trial

The aim of this study was to compare two intensities of LLLT on wound healing process of the donor palatine area after CTG removal.

This is a prospective, parallel and controlled clinical trial. The population evaluated in the study was selected at Science and Technology Institute - ICT- São José dos Campos, College of Dentistry. Patients were assigned to one of the three treatment groups: Group 60 (Test, n=18): Periodontal surgery for root coverage through connective tissue graft and LLLT application on donor site using a 60 J/cm² dose. Group 30 (Test, n=18): Periodontal surgery for root coverage through connective tissue graft and LLLT application on donor site using a 30 J/cm² dose. Group Sham (Control, n= 18): Periodontal surgery for root coverage through connective tissue graft and LLLT SHAM on donor site. All surgeries were performed by the same expert periodontist (MPS). Before the surgical procedure, all patients were enlightened about the causes and consequences of gingival recession and prevention techniques. Factors related to the origin of gingival recession, such as toothbrush trauma and inflammation caused by biofilm, were controlled through instruction on standardized brushing technique to avoid the influence of other hygiene methods capable of promoting trauma on soft tissues. Standardized dental floss and toothbrushes were given to patients. The surgical technique adopted in the recession defects was the trapezoidal-type of CAF and the connective tissue graft was removed from palate mucosa . Briefly, a first incision on the palate was performed perpendicularly to the long axis of the teeth, 2 to 3 mm apical to the gingival margin. The mesial-distal length of the incision was determined by the length of the graft required to cover the recession. Because the selected recessions were in maxillary canines and premolars, the lengths of the graft varied minimally (10-12mm). The second incision was made parallel to the first one (1-2 mm apically and parallel to the long axis of the teeth) to separate the subepithelium connective tissue from the epithelial layer. The incision is carried far enough apically to provide a 7- mm height of connective tissue to cover the denuded root surface. Afterward, another incision parallel to the long axis of the teeth starting from the first incision was performed to separate the subepithelium connective tissue from the periosteum. Then, the connective tissue graft was removed from the palate as atraumatically as possible. Single sutures were made on the palate (4-0 silk) and the graft was sutured on the receptor site. The evaluated parameters were wound remaining area (WRA), scar and tissue colorimetry (TC), tissue thickness (TT) and postoperative discomfort (D), evaluated at baseline and 7, 14, 45, 60, and 90 days after surgery. Statistical Analysis: All data were expressed as mean ± standard deviation or expressed in percentages during the descriptive phase. Data were analyzed according to distribution by the Shapiro-Wilk test. For the remaining wound area, tissue colorimetry, tissue thickness, and postoperative discomfort parameter analysis, two way repeated measures ANOVA was performed for intra- and intergroup analysis. T test was used for intergroup comparison of the number of analgesics taken. The presence or absence of scars was measured by Q-square test. Statistical analysis was performed using Sigma Plot 12.0. In all tests a significance level of 0.05 was chosen.

The patients allocated to the control group received sham irradiation. For this, black rubber protection was placed at the tip of the laser device, which did not allow the light to reach the tissue. The applications were performed by a different operator (CAS) from the one who measured the study parameters. During irradiation, the tip of the laser probe was placed perpendicularly with slight contact on the area. Laser therapy was initiated in the immediate postoperative period (just after sutures) and was repeated by six more applications performed every other day, with a total of 7 laser applications.

The irradiation was performed with a GaAlAs diode laser that continuously emitted a wavelength of 660 nm with a power of 30 mW. The patients allocated for the group 60 received the following protocol for laser application: Two (2) points of irradiation were performed using a total energy density (fluence) of 60 J/cm2 and a time of 60 seconds (30 J/cm2 per point and an application time of 30 seconds per point). During irradiation, the tip of the laser probe was placed perpendicularly with slight contact on the area. Laser therapy was initiated in the immediate postoperative period (just after sutures) and was repeated by six more applications performed every other day, with a total of 7 laser applications. The power of the equipment was calibrated prior to each application.

The irradiation was performed with a GaAlAs diode laser that continuously emitted a wavelength of 660 nm with a power of 30 mW. The patients allocated for the group 30 received the following protocol for laser application: Two (2) points of irradiation were performed using a total energy density (fluence) of 30 J/cm2 and a time of 30 seconds (15 J/cm2 per point and an application time of 15 seconds per point). During irradiation, the tip of the laser probe was placed perpendicularly with slight contact on the area. Laser therapy was initiated in the immediate postoperative period (just after sutures) and was repeated by six more applications performed every other day, with a total of 7 laser applications. The power of the equipment was calibrated prior to each application.

For this, standardized photographs were taken (brightness, distance and angle). A scale was used as a reference to measure this area. These photographs were exported to image software ( Image J - NIH, Bethesda, USA) and remaining wound area was measured in square millimeters (mm²).

After air jet application, patients were requested to score postoperative discomfort through on a visual analogue scale (VAS) of 10 centimeters, in which 0 meant "no pain" and 10 meant "extreme pain". After this, a postoperative discomfort average for all groups was obtained.

Through four fixed points marked 5 and 7 mm from the gingival margin in the operated region, tissue thickness of palatine masticatory mucosa. One stent was made to standardize the points to be measured. The stent was positioned, and with a periodontal probe and the points were marked. Then the stent was removed and measurements were taken. For this, an endodontic spacer with a rubber cursor was put on the marked points for it to reach the palatine bone plate. Then the cursor was taken to the tissue carefully to not pressuring it. The distance between the spacer tip and the cursor was measured using a digital pachymeter and measured in millimeters (mm).

Inclusion Criteria: Patients were 20 to 70 years old and of both genders, presenting Class I or II Miller gingival recession on vital canines or premolars in the palatine region (donor site) with no pathological or morphological alterations. Patients agreed to and signed the formal consent to participate in the study after receiving an explanation of risks and benefits from an individual who was not a member of the present study (Resolution no. 196 - October, 1996, and Ethics and Code of Professional Conduct in Dentistry - CFO 179/93). Exclusion Criteria: Were excluded patients with systemic problems that contraindicated surgical procedure Those under medication that could interfere with the wound healing Those who smoked Those who were pregnant or lactating, and Those who had had periodontal surgery on the study area.

Zucchelli G, Amore C, Sforza NM, Montebugnoli L, De Sanctis M. Bilaminar techniques for the treatment of recession-type defects. A comparative clinical study. J Clin Periodontol. 2003 Oct;30(10):862-70. doi: 10.1034/j.1600-051x.2003.00397.x.

Bruno JF. Connective tissue graft technique assuring wide root coverage. Int J Periodontics Restorative Dent. 1994 Apr;14(2):126-37.

da Silva Neves FL, Silveira CA, Dias SB, Santamaria Junior M, de Marco AC, Kerbauy WD, de Melo Filho AB, Jardini MA, Santamaria MP. Comparison of two power densities on the healing of palatal wounds after connective tissue graft removal: randomized clinical trial. Lasers Med Sci. 2016 Sep;31(7):1371-8. doi: 10.1007/s10103-016-1988-6. Epub 2016 Jun 25.