VST vs Modified Periosteal Inhibition Technique

Overview

Losing a tooth in the upper front of the mouth is common, and many people choose a dental implant to replace it. When a tooth is removed, the thin layer of bone in front of the socket - the buccal, or front, bone - often shrinks as the area heals. If this bone shrinks, the final implant can look less natural and the gum can recede. The problem is greater when part of the front bone is already missing at the time the tooth is taken out; this type of socket is harder to treat. This study compares two surgical techniques that aim to protect the front bone and gum while a dental implant is placed on the same day the tooth is removed. In Vestibular Socket Therapy (VST), a thin bone membrane is inserted through a small incision high in the gum fold to cover the front bone, and bone graft material is packed into the socket. In Modified Periosteal Inhibition (MPI), a thin bone membrane is placed against the outside of the front bone and held in place with a tissue glue, and the socket is filled with a collagen sponge. Adults aged 20 to 50 with a non-restorable upper front tooth (canine to canine) and partial loss of the front bone can take part. Participants are randomly assigned to one of the two techniques and receive an implant immediately after the tooth is removed, then are followed for 12 months. Using cone-beam CT scans, intraoral scans, and an esthetic (appearance) score taken at the start and at 6 and 12 months, the investigators measure the thickness of the front bone, the level and thickness of the gum around the implant, and the overall appearance. The study tests whether one technique preserves or increases the thickness of the front bone and produces better gum and esthetic results than the other.

Background: Tooth extraction produces dimensional changes of the alveolar ridge that are most pronounced in the anterior maxilla. Extraction sockets with a partially missing buccal plate but intact facial soft tissue (Elian Class II) are particularly difficult to manage, because loss of the facial bone after immediate implant placement can lead to soft-tissue recession and a compromised esthetic result. Several approaches have been proposed to protect or reinforce the facial bone at the time of immediate placement. Vestibular Socket Therapy (VST) uses a cortical bone membrane delivered through a vestibular access incision to cover the facial socket wall, together with particulate bone graft and a customized healing abutment that seals the socket. Modified Periosteal Inhibition (MPI) places a resorbable xenogenic cortical bone lamina between the labial periosteum and the labial bone plate, fixed with a cyanoacrylate tissue adhesive, with the socket filled by a collagen sponge. Both techniques are used with immediate implant placement, but they have not been directly compared. Objective: To evaluate and compare VST versus MPI, each combined with immediate implant placement, for the management of compromised (Elian Class II) extraction sockets in the maxillary esthetic zone, with respect to facial bone thickness, peri-implant soft-tissue level and thickness, and esthetic outcomes. Design: This is a single-center, parallel-group, two-arm randomized controlled clinical trial with 1:1 allocation, conducted at the Faculty of Dentistry, Tanta University. Forty-two eligible participants with a non-restorable maxillary anterior tooth and an Elian Class II socket confirmed on cone-beam computed tomography (CBCT) are allocated to one of two groups (21 sites each) using sequentially numbered, opaque, sealed envelopes (SNOSE). Outcome assessment and statistical analysis are performed blinded to group allocation. Sample size: The target of 42 participants (21 per group) provides 80% power at a 5% significance level to detect the difference in buccal bone gain reported for the two techniques in prior studies, using the larger standard deviation to yield an effect size of approximately 0.925 (G\*Power 3.1.9.7); the figure includes an allowance for dropout. Interventions: All participants first receive phase I periodontal therapy (scaling and root planing, oral-hygiene instruction). The non-restorable tooth is extracted atraumatically and the socket is debrided and confirmed as Elian Class II with adequate interproximal bone. In both groups the implant is placed using a computer-guided surgical template, with the implant shoulder positioned 3 to 4 mm apical to the labial gingival margin. In the VST group, a xenogenic cortical bone membrane trimmed to the facial socket wall is inserted through a vestibular access incision and stabilized with bone tacks, and particulate xenograft is placed in the socket. In the MPI group, a conservative full-thickness flap is raised, and a resorbable xenogenic bone membrane is placed between the labial periosteum and the labial bone plate, fixed with cyanoacrylate adhesive, with a collagen sponge placed in the socket. In both groups the socket is sealed with a customized healing abutment and closed with non-resorbable sutures. Postoperative care includes a chlorhexidine 0.1% rinse, an amoxicillin-clavulanate and metronidazole antibiotic regimen, and ibuprofen. Assessment: Participants are evaluated at baseline, 6 months, and 12 months. Facial bone thickness and peri-implant bone levels from crest to apex are measured on CBCT. Peri-implant mucosal level and mucosal thickness are assessed by superimposing intraoral scan (STL) files on CBCT-derived data, and esthetics are scored using the simplified pink esthetic score. Data are summarized as means and standard deviations, with within-group and between-group comparisons at a significance level of p \< 0.05; analysis is carried out blinded to group.