RESUMO
OBJECTIVES: To evaluate the ridge alterations and esthetic outcome 1 year after immediate implant placement using the dual-zone (DZ) technique versus the bone shielding concept in patients with intact thin-walled sockets in the esthetic zone. MATERIAL AND METHODS: This randomized clinical trial included 26 patients with nonrestorable maxillary teeth in the esthetic zone who were randomly assigned to two groups (n = 13 each) to receive immediate implants using either the bone shielding concept or DZ. Definitive restorations were delivered after 2 months. Pink esthetic scores (PESs), vertical soft tissue alterations, and bucco-palatal ridge dimensional changes were measured and assessed using intra-oral digital scans at baseline and 1 year post-procedure. Labial bone thickness was measured using cone beam computed tomography scans at baseline and after 1 year. RESULTS: The bone shielding group provided bucco-palatal ridge thickness stability after 1 year (9.43 mm) compared to baseline values (9.82 mm), while DZ showed a significant loss in the bucco-palatal ridge thickness after 1 year (7.83) compared to baseline values (9.49). No significant difference was reported in the baseline bucco-palatal ridge thickness between the two groups (p = 0.6). After 1 year, the bone shielding group demonstrated 0.38 mm ridge shrinkage which was statistically significant (p = 0.0002) compared to 1.67 mm ridge shrinkage in the DZ group. In addition, the average total PES in the bone shielding group was 12.04 versus 10.28 in the DZ group. No significant difference was reported in the mesial papilla length between the DZ and the bone shielding group after 1 year (p > 0.05). However, the midfacial gingival margin (p = 0.026) and distal papilla were significantly higher in the DZ group (p = 0.0025). There was no significant difference in the mean ± SD mm bone gain at the apical level between the two studied groups after 1 year (p = 0.06) showing 0.85 ± 0.23 and 0.64 ± 0.32 mm, respectively. However, the bone shielding concept showed a statistically significant more bone gain mm (p < 0.001) at the (0.56 ± 0.43) and crestal (0.03 ± 0.8) levels after 1 year compared to DZ which revealed 0.18 ± 0.5 and 0.38 ± 0.29 mm bone loss, respectively. CONCLUSION: The bone shielding concept might offer a reliable alternative for restoring thin-walled sockets by minimizing postextraction ridge dimensional alterations effect following immediate implant placement in the esthetic zone. Nevertheless, the study suffers from confounding bias since there are two systematic differences between the groups, the barrier membrane type, and the level of bone filling. "This clinical trial was not registered prior to participant recruitment and randomization." CLINICAL TRIAL REGISTRATION: NCT05381467.
