Study design and population
The design of the present study was quasi-experimental and the gathered data analyzed before and after the intervention. The study population consisted of patients who referred periodically to the Department of Periodontics at the Faculty of Dentistry, Kerman University of Medical Sciences, with inadequate attached gingiva associated with single-rooted teeth of mandibular jaw (premolars, canines or incisors). The participants were entered in this study by non-probability sampling (convenience) method. The sample size was calculated considering α =0.05, β =0.2, d =1.15, and in view of the standard deviation difference (2.5) and mean difference (1.8) acquired in hatipoglu’s study (12). The result was 18 cases and by taking into account the 10 percent possibility of sample loss, sample size was set on 20.
The criteria for inclusion in the study were as follows: the need for gingival augmentation in single-rooted teeth of mandibular jaw considering KGW <2 mm, AGW <1 mm, no need for root coverage, need for prosthetic or orthodontic treatments, need for improvement of oral hygiene, no systemic diseases that contraindicated periodontal surgery, not using medications affecting on periodontium, no pregnancy, no smoking, no traumatic occlusion and acceptable oral hygiene (O'Leary plaque index less than 20%). The exclusion criteria in this study were as follows: poor oral hygiene, need to use medication affecting the periodontium during follow-up period, incomplete follow-up data.
Prior to conducting this study, the procedure was fully explained to each patient, potential problems were identified, and then a consent form was signed by the participants. This study was approved by the Kerman University of Medical Science with ethics code of IR.KMU.REC.1391.06 and with IRCT registration number: IRCT20101204005305N18 (Registration date 2019-09-22).
KGW, AGW, PD, and VD were measured before surgery. The KGW [the mid-buccal distance from the gingival margin to the mucogingival junction (MGJ) of the tooth] was determined by a Michigan-O-Probe* with 0.5-mm accuracy using a Roll technique to determine MGJ and then, the mid-buccal AGW was calculated by subtracting the gingival probing depth (PD) from the KGW.
To determine the VD, alginate impression was prepared from the patient and special tray was made after casting. Then, after border molding, an alginate impression was taken again. After preparation of final cast, the deepest part of the vestibule was marked with a pencil and the distance of the mid-buccal gingival margin to the line marked in the vestibular depth was measured in millimeter (Fig.1).
After prepping and draping, local anesthesia† was injected (2% lidocaine with 1/100,000 epinephrine) in recipient and donor sites. In the recipient bed, a partial-thickness incision was made using a 15c blade. the coronal incision was made sub-marginally at the MGJ, and two vertical incisions were created 10 mm apart and were extending apically as far as the vestibules allowed at a height of at least 9 mm, at both ends of the horizontal incision. The mesial and distal incisions were then connected apically. Any muscle fibers were removed with scissors creating an appropriate periosteal bed. Then, the FGG was prepared by using a mucotome‡ with a thickness of 1.5 mm and a dimension of 9 x 10 mm from the palatal area of the maxillary premolars and first molar with preserving the marginal gingiva at donor site (containing epithelium and a thin layer of underlying connective tissue). The reason for using the mucotome was to equalize the graft thickness. The graft donor site was covered with periodontal dressing after suturing with a 5-0 silk suture§.
The prepared FGG was adapted on the recipient bed and the lip or cheek adjacent to the graft was placed under tension to make certain that the grafts were free of movement during muscle traction. The graft stabilized with a 5-0 seralon® suture¶. Interrupted sutures were applied in the coronal border and vertical stabilizing sutures were used for graft fixation. Then, FGG in the recipient site was covered with periodontal dressing.
After surgery, the patients were advised not to brush the treated sites within two postoperative weeks, and instructed to use a soft diet. Chlorhexidine mouthwash 0.2% was prescribed twice daily for 4 weeks and ibuprofen 400 mg tablets were also prescribed every 6 hours as needed. After two weeks, dressing and sutures were removed, the surgical sites were washed with normal saline and plaque control was initiated by the patients.
Post-surgery measurements were consisted of PD, VD, KGW and AGW, HGD, VGD and GA. The HGD and VGD were measured in the midway of apico-coronal and mesio-distal dimensions of FGG (Fig. 2). The GA was calculated by multiplying its length and width. The shrinkage percentage of VGD and HGD and the GA shrinkage were calculated using the following Formulas.
The above measurements were repeated 1, 3 and 6 months after surgery.
Data were analyzed using SPSS 18 software. Kolmogorov-Simonov test was performed to analyze the normal distribution of the data. Given the normal distribution of the data, T-test and repeated measurement test were applied.