PMC5303851_01
Maxillary right central and lateral incisors before extraction (a). Note extrusion of central and lateral incisors, migration of central incisor, and persistent inflammation (b). Preoperative radiographs showing severe interdental bone loss and widening of the residual periodontal ligament space as a consequence of the occlusal trauma (c). Intraoperative view following teeth removal (d). Occlusal view showing vertical bone resorption and partial nonspace maintaining defect at central incisor (e). After placement of a nonresorbable d-PTFE membrane to replace the missing buccal bony wall, the gap between the membrane and the residual palatal wall was filled with the collagen sponge (f). Flaps were repositioned and the membrane was left partially exposed and protected with the collagen sponge (g).
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fig1
Both teeth were extruded and tooth number 8 exhibited pathologic migration with a midline diastema of 2-3 mm (Figures 1(a)-1(c)). The analysis of the alveolar sockets morphology confirmed the complete buccal bone wall deficiency at tooth number 8 and a vertical bone height deficiency of about 9 mm on its palatal side (Figures 1(d)-1(e)). A commercially available bioabsorbable sponge of equine lyophilized type I collagen (Gingistat, GABA, Italy) was used to fill the gap between the membrane and the residual palatal wall (Figure 1(f)). Intentional primary closure was not attempted and the membrane was left partially exposed and protected by the collagen sponge (Figure 1(g)).
At 4 months the extraction sockets were completely filled by uniform radiodense bone tissue. Note the ridge morphology mimicking the space created beneath the membrane.
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fig2
After flap elevation, bone formation was observed with a ridge morphology mimicking the space created beneath the membrane (Figure 2).
One year after the ridge reconstruction procedure ridge regeneration was achieved. Buccal view (a); occlusal view (b); cone-beam computed tomographic scan (c).
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Resolution of the alveolar bone deficiencies on tooth number 8 and limiting of the physiologic ridge reduction were attained (Figure 3).
Bone biopsy illustrating socket healing 4 months after the ridge reconstruction procedure. Hematoxylin and eosin staining. Total magnification: x100 ((a), central incisor; (b), lateral incisor).
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The overall mean percentage of newly formed bone was 49.3%  +-  4.7% and was composed mostly by lamellar bone (33.2%  +-  3.6%) (Figure 4).