Alveolar ridge preservation with a free gingival graft in the anterior maxilla: volumetric evaluation in a randomized clinical trial

Abstract

The aim of this study was to evaluate and compare the dimensional changes in maxillary extraction sockets that have healed spontaneously and those treated with free gingival grafts. Ten subjects with at least two maxillary anterior teeth scheduled for extraction were selected for this study. Two maxillary teeth were allocated randomly to either the test group or the control group. In the test group, the extraction socket was covered with a free gingival graft harvested from the palate, while in the control group the sockets healed spontaneously. Cone beam computed tomography (CBCT) scans were taken on the day of extraction and at 3 months postoperative. Soft tissue healing of the extraction sockets was assessed visually by clinical inspection. Hard tissue measurements were obtained from the CBCT scans. After 3 months of healing, the control sockets had lost height in the buccal and lingual crestal bones (−1.03 and −0.56 mm, respectively); however, the height in the buccal and lingual crestal bones was preserved at the test sites (+0.06 and +0.25 mm, respectively). This difference between the two groups was statistically significant ( P < 0.05). In contrast, both the control and test groups lost width in the buccal and lingual crestal bones; the difference between the control and test groups was not statistically significant ( P > 0.05). The authors propose that covering the orifice of the extraction socket with a free gingival graft can result in preservation of the alveolar bone height.

Alveolar ridge resorption is a complicated process that includes structural, functional, and physiological components. Periodontal disease, peri-apical pathologies, and mechanical trauma cause loss of the bone surrounding the teeth. Age, gender, systemic conditions, facial morphology, traumatic dental extractions, and functional stress on the extraction wound are also predisposing factors that affect alveolar bone loss following tooth extraction.

The rate of alveolar ridge resorption following tooth removal is rapid in the first 6 months and continues at a mean 0.5–1% a year for life. Lekovic et al. emphasized that 40% of alveolar bone height and 60% of alveolar bone width are lost within the first 6 months after tooth extraction. Schropp et al. reported that approximately 50% of the original alveolar bone width is reduced within the first 12 months after tooth extraction, and two-thirds of this resorption occurs in the first 3 months. This resorption can significantly affect the position, angulation, and prognosis of a dental implant, as well as the hard and soft tissue aesthetics.

Alveolar ridge preservation techniques have recently been applied to eliminate or decrease bone loss after tooth extraction. Several studies have proposed various ridge preservation techniques, including the placement of mineralized or non-mineralized graft materials, the use of membranes or soft tissue grafts to cover the extraction socket entrance, immediate implant placement, buccal overbuilding, and tissue engineering techniques. Demineralized bovine bone material has frequently been utilized as a graft material to preserve the alveolar ridge width and height. Although this has been shown to be effective for protecting bone volume, graft material residue has been observed in the socket even after 7–9 months. In a recent study by Lindhe et al., the authors emphasized that the tissue modelling and remodelling process in the augmented sockets is delayed with the use of Bio-Oss Collagen. Similar results have been presented in other studies in which different graft materials have been used to preserve ridge dimensions. The free gingival graft has also been used for alveolar ridge preservation in animal and human studies. This graft is preferred as it eliminates the need to elevate a full thickness mucoperiosteal flap and compensates for soft tissue deficiencies when immediate implant placement or a socket augmentation procedure is required. However, in some of the human studies that used the free gingival graft to cover the extraction socket, dimensional changes in the alveolar ridge were investigated using study casts or the master casts.

The aim of this study was to determine the dimensional changes in the maxillary anterior extraction socket after 3 months of healing in humans, comparing sockets covered with a free gingival graft to those left to heal spontaneously using cone beam computed tomography (CBCT) scans. This study is reported in accordance with the CONSORT guidelines.

Materials and methods

This split-mouth, unblinded, randomized controlled clinical study was performed in accordance with the Declaration of Helsinki and was approved by the institutional ethics committee. Written informed consent was obtained from all patients.

Study population

Ten adult patients (five females, five males) ranging in age from 36 to 60 years (mean 46.7 years) participated in this study between September 2011 and November 2012. Each patient had at least two maxillary anterior teeth that required extraction. Seven patients underwent multiple extractions in the anterior maxilla; the remaining three patients had two maxillary anterior teeth removed. However, only two extraction sockets per patient were included in the study. The 20 extraction sockets in these 10 patients were allocated randomly to one of two groups using a random number table: (1) a test group, in which the socket was covered with a free gingival graft and treated with the socket seal technique; (2) a control group, in which the extraction socket was allowed to heal spontaneously ( n = 10 per group). The randomized codes were enclosed in sequentially sealed envelopes. Following the tooth extractions, the envelopes were opened and it was determined whether each extraction socket was to be used as a test site or control site.

Patient demographic data and information on the teeth included in this study are presented in Table 1 . The indications for extraction were advanced periodontal disease and/or prosthetic reasons. Exclusion criteria were the presence of uncontrolled systemic disease, any systemic condition compromising wound healing, and acute periodontal and/or odontogenic infection.

Table 1
Data for the patients included in the study.
Patient Gender Age, years Total number and positions of extracted teeth Control group Test group
1 Male 36 3 (11, 12, 13) 12 13
2 Male 38 4 (11, 12, 21, 22) 22 12
3 Male 57 3 (11, 21, 13) 11 21
4 Female 48 2 (12, 21) 12 21
5 Female 46 4 (11, 21, 22, 23) 21 11
6 Female 39 2 (13, 23) 13 23
7 Female 48 2 (21, 11) 21 11
8 Male 40 4 (11, 12, 21, 22) 12 11
9 Female 55 4 (11, 12, 21, 22) 12 22
10 Male 60 3 (21, 22, 23) 21 23

Surgical procedure

All patients were treated with scaling and root planing prior to the study and demonstrated good oral hygiene and compliance. On the day of extraction, following the administration of local anaesthesia (Maxicaine; Vem Medicine, Turkey), the teeth were carefully extracted without the elevation of a mucoperiosteal flap or compromising the marginal gingiva ( Fig. 1 ). Care was taken to perform an atraumatic extraction to protect the periosteum and alveolar bone. The sockets were curetted to remove granulation tissue. The extraction sockets were assigned randomly to be a control site or a test site.

Fig. 1
Intraoral appearance following tooth extractions.

In the control group, blood clots were allowed to form in the extraction socket and they were left to heal spontaneously. In the test group, the internal marginal gingiva of the extraction socket was de-epithelialized with a number 15 scalpel to encourage vascularization of the free gingival graft. A trephine bur with a diameter corresponding to that of the socket orifice was chosen. A free gingival graft of approximately 2–3 mm in thickness was cut from the palate with this selected trephine bur and gently dissected using a sharp periosteal elevator, in accordance with the technique of Jung et al. ( Fig. 2 ). The flap was adapted to the site and sutured to the marginal gingiva with six to eight interrupted sutures (4–0 Vicryl; Ethicon, Johnson & Johnson, USA). The donor site was covered with a Xeroform sponge to allow for secondary healing ( Fig. 3 ).

Fig. 2
Trephine bur with a diameter corresponding to that of the socket orifice, and a free gingival graft harvested from the palate.

Fig. 3
Right and left maxillary canines were included in this study. In this photograph, the left maxillary canine has been covered with a free gingival graft and the right maxillary canine has been left to undergo secondary healing.

The patients were prescribed oral antibiotics, non-steroidal anti-inflammatory drugs, and antiseptic mouthwash. The Xeroform sponge was removed from the palate 3 days later and the sutures were removed 10 days after surgery. All patients were recalled at 3, 7, and 10 days and at 1 and 3 months postoperatively.

Cone beam computed tomography (CBCT) measurements

To determine the alterations in the alveolar ridge following tooth extraction, CBCT scans were taken at baseline (the day of tooth extractions) and at 3 months postoperative using Veraviewepocs 3D (J. Morita Corp., USA). The tube potential, tube current, and rotation time were set to 80 kVp, 6 mA, and 9.4 s, respectively. The images were taken with a slice thickness of 1.5 mm and a slice distance of 1 mm, with a field of view (FOV) of 4 × 4 cm.

The radiographic measurements were obtained from the sagittal sections of the CBCT scans using computer software. The localization of the sagittal section was determined on the basis of anatomical landmarks in the axial and coronal sections. The reference points were the incisive foramen in the axial section and the median palatine suture in the coronal section. The horizontal line passing through the centre of the incisive foramen in the axial section was used to find the coronal section, and the parallel line passing through the midline of the median palatine suture was accepted as an initial section. The distance between the initial section and the section of the extraction socket was determined for the sagittal section to be measured ( Fig. 4 ). Subsequently, the measurements were made at baseline and at 3 months using the same reference points and the same millimetre distances.

Fig. 4
Axial, coronal, and sagittal sections of a CBCT scan.

The heights and widths of the extraction sockets were measured in the buccal and lingual aspects according to the technique of Araújo and Lindhe. To set a reference in each sagittal section, a line from the apex of the socket to the most coronal part of the socket through the long axis of the extraction socket was drawn to separate the buccal and lingual compartments. From the most coronal point of the buccal and lingual crest, two horizontal lines perpendicular to this line were drawn to measure the widths of the buccal and lingual bone walls. The vertical distances under these horizontal lines were also determined and taken as the height of the buccal and lingual bone walls ( Fig. 5 ).

Fig. 5
Measurements made on the sagittal section. v-bc: height of the buccal crest; v-lc: height of the lingual crest; h-bc: width of the buccal crest; h-lc: width of the lingual crest.

Differences in the alveolar ridge dimensions measured at baseline and at 3 months were expressed in millimetres; values were positive in the case of a gain or negative in the case of loss of the bony wall.

The CBCT measurements were done by the same researcher using the same technique at the two different time points. Therefore, the reliability of the measurement technique was also evaluated statistically.

Statistical analysis

The statistical analysis was performed using a statistical software program developed by a statistician in the Division of Biostatistics, University of Hacettepe. Descriptive statistics were used to indicate the medians and the minimum and maximum values in each treatment group.

Differences in the dimensional changes of the alveolar ridge at the control and test sites after 3 months of healing were tested by one-way analysis of variance (ANOVA) for repeated measures. Differences between the test group and the control group after 3 months were analysed using the Mann–Whitney U -test; differences in measurements from the test and control sites for each time point were examined using the Wilcoxon signed rank test. 95% Confidence intervals were calculated. The level of significance was set at P < 0.05.

The intra-class correlation coefficient (ICC) was used to evaluate the reliability of the measurements that were performed by the same researcher at the two different time points. The reliability of the measurements was defined as ‘poor’ if the ICC was <0.40, as ‘acceptable’ if the ICC was between 0.40 and 0.70, and as ‘good’ for ICC values >0.70.

Results

All patients completed the study. No postoperative complications were recorded in either group. All extraction sites healed uneventfully.

Qualitative analysis

Soft tissue healing of the extraction sockets was assessed visually by clinical inspection on days 3, 7, and 10 and months 1 and 3 postoperatively. No measurements of soft tissue volume were recorded for the preoperative or postoperative period.

After 3 days of healing, the extraction sockets in the control group exhibited epithelial invagination into the socket centre, and the tissue shrinkage resulted in a reduction in the bucco-palatal dimension. In the test group, degeneration and sloughing of the epithelium occurred. The grafts became softened and swollen ( Fig. 6 ).

Fig. 6
Photograph taken after 3 days of healing. The control site extraction socket has epithelialized. At the test site, degeneration and sloughing of the epithelium has started.

After 7 days of healing, the graft surfaces in the test group exhibited superficial necrosis. All surfaces were ischaemic and yellowish-white. The healing of the sockets in the control group had nearly completed.

After 10 days of healing, the swelling of the free gingival grafts in the test group had decreased due to increasing nutrition. Vascularized tissue was observed between the marginal gingiva and the gingival graft, although the necrosis in the centre of the socket continued. The sockets in the control group had healed completely ( Fig. 7 ).

Fig. 7
Photograph taken after 10 days of healing. The control site has healed completely. Superficial necrosis of the gingival graft is seen at the test site, but vascularization has started at the peripheral margins of the graft.

After a month of healing, the grafts were completely integrated into the surrounding gingiva. No necrosis was observed in any graft. The grafts were healthy in colour, and their thicknesses around the gingiva were similar. Three months later, although it was difficult to distinguish the control and test sites, significant invaginations in the bucco-palatal dimension at the control sites were observed ( Fig. 8 ).

Fig. 8
Photograph taken after 3 months of healing. The graft is completely integrated (green arrow). Bucco-lingual invagination is observed at the control site (blue arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)

The Xeroform sponge was removed 3 days after the tooth extractions. All patients suffered mild to moderate pain until epithelialization of the donor site had completed. However, the sites healed uneventfully within 2 weeks.

Quantitative analysis

The measurements obtained for the 10 patients and the results of the dimensional changes after 3 months are displayed in Tables 2 and 3 , respectively.

Table 2
Initial and final measurements for each of the 10 study patients. a
Patient Initial, mm Final, mm
Control site Test site Control site Test site
1
v-bc 9.65 5.29 4.31 4.62
v-lc 8.44 3.90 5.24 5.55
h-bc 3.85 5.02 2.62 2.31
h-lc 3.22 2.62 3.08 2.62
2
v-bc 10.2 6.41 8.53 8.07
v-lc 9.90 6.74 8.41 8.22
h-bc 4.19 3.92 2.88 2.73
h-lc 2.16 4.62 2.29 3.21
3
v-bc 7.25 9.85 7.09 9.58
v-lc 7.53 8.23 8.78 8.46
h-bc 3.41 5.02 2.47 4.00
h-lc 4.72 4.04 3.39 3.96
4
v-bc 4.78 2.96 4.47 3.38
v-lc 3.81 5.09 3.16 6.50
h-bc 3.97 3.16 3.06 2.35
h-lc 2.91 3.42 3.05 2.35
5
v-bc 6.82 7.81 6.13 6.39
v-lc 6.62 6.15 6.15 6.43
h-bc 3.73 4.00 2.96 3.68
h-lc 4.41 3.95 3.86 3.70
6
v-bc 12.96 6.58 12.43 7.75
v-lc 15.64 9.57 13.72 7.95
h-bc 3.94 3.17 2.62 2.97
h-lc 3.72 3.59 3.44 2.49
7
v-bc 7.27 9.15 5.83 6.88
v-lc 5.61 5.55 5.53 5.46
h-bc 3.61 3.66 2.20 2.43
h-lc 3.66 3.32 2.39 2.39
8
v-bc 4.72 2.09 3.42 3.33
v-lc 3.75 6.48 3.39 6.86
h-bc 3.41 2.83 1.73 1.87
h-lc 3.61 5.68 3.53 4.08
9
v-bc 9.38 7.38 8.61 7.78
v-lc 7.30 7.59 7.51 7.43
h-bc 3.79 4.20 3.38 3.54
h-lc 3.04 2.75 2.83 2.91
10
v-bc 5.75 14.52 3.81 14.14
v-lc 5.45 9.89 4.68 8.93
h-bc 3.17 4.93 1.95 3.75
h-lc 5.57 3.08 4.72 3.80
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Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Alveolar ridge preservation with a free gingival graft in the anterior maxilla: volumetric evaluation in a randomized clinical trial
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