Changes of the alveolar ridge dimension and gingival recession associated with implant position and tissue phenotype with immediate implant placement: A randomised controlled clinical trial

PURPOSE: This prospective, randomised, controlled clinical trial evaluated the relationship between alveolar ridge dimensional change and recession with the implant position (horizontal and vertical) and tissue phenotype in immediately placed and provisionalised implants without the use of bone grafting. MATERIALS AND METHODS: Patients (n = 40) with a hopeless maxillary anterior tooth received an immediate implant and immediate provisional or customised healing abutment after flapless extraction. Implants were finally restored 3 months after placement and followed up for 6 months after delivery of the restoration. The alveolar ridge dimensional change and recession were measured using cone beam computed tomography (CBCT) scans and digitalised dental casts. Alveolar contour changes were correlated to implant position and tissue phenotype. RESULTS: The tissue phenotype showed no significant correlation to the alveolar ridge dimensional change. At 6 months, the average alveolar ridge dimensional change was approximately 0.7 mm in the buccolingual dimension independent of tissue phenotype. A statistically significant difference was observed on the recession values comparing tissue phenotypes, with more recession observed in the thin phenotype (1.96 mm) than in the thick phenotype (1.18 mm). A significant correlation was observed between horizontal implant position and buccolingual alveolar ridge change. A positive correlation was observed between the horizontal implant position and the dimensional change measured in the casts at the level of the free gingival margin. A statistically significant negative correlation was observed between the horizontal implant position and the resorption measured by the CBCT scans. CONCLUSIONS: Patients with thin tissue phenotype had a more marked recession. The horizontal implant position showed a relationship to the alveolar ridge dimensional changes observed. The greater the buccal gap distance between the implant and the buccal plate, the lesser the radiographic changes observed in the alveolar bone, however, the greater the changes observed in the buccal aspect of the casts at the level of the free gingival margin.