Maxillary Single-Stage Immediate-Load Microthreaded Implants at 2 Years

Maxillary Single-Stage Immediate-Load Microthreaded Implants at 2 Years
R.A. YUKNA, S. VASTARDIS, and E.T. MAYER, Louisiana State University, New Orleans, USA
March 2004
Clinical Implant Studies
Objective: Evaluate Ti-O-blasted dental implants (DI) with microthreads in the coronal portion (AstraTech) in a single-stage immediate loading technique in edentulous maxillae after 2 years in function. Methods: At 4 international centers, patients received 1-stage DI placement, then used a relined maxillary prosthesis after the first 2 weeks. After > 6 months, the healing abutments were replaced by permanent abutments and fixed bridges placed. 371 DI (5 - 10 DI per maxilla) > 9 mm long were placed in native bone (most in type III or IV bone) in 54 patients (29 were habitual smokers). Standardized xrays taken at -6, 0, 6, 12, 24 months after bridge delivery were blindly evaluated to the nearest 0.1 mm. Results: 33 DI were removed before loading (initial survival rate = 91.1%). No DI have been lost in the 2 years after loading (survival rate loading ÇƒÏ 2 years = 100%). DI failures were significantly higher (3X) in smokers. At loading patient mean marginal bone levels were 1.80 mm (SD 0.90), a loss since placement of 1.46 mm (SD 0.88). Net bone height gain of 0.35mm (SD 0.64) has occurred since loading out to 24 months. This overall DI survival rate, pre-loading marginal bone loss, and subsequent marginal bone gain suggest that the fairly large initial bone loss reported in this study was not DI-related, but related to the use of a removable complete prosthesis with a 1-stage immediate loading procedure. Conclusion: The 2 year results of this study suggest that the early DI failures were significantly higher in smokers and marginal bone loss (which occurred during healing period) is comparable to what has been reported for other single stage DI. Following loading, bone levels are stabilized and improve over 2 years with 1-stage immediate-load microthreaded implants in edentulous maxillae. Supported by AstraTech AB