A Retrospective Study of Bone Level Stability Around 441 Mandibular and 350 Maxillary Molar Implants Placed with an Immediate Implant Protocol

The purpose of this retrospective study was to evaluate bone level stability around 441 mandibular and 350 maxillary molar implants, placed using an immediate implant protocol, that had been in function from 2 to 17 years postrestoration (mean: 9.9 years). Independent radiographic measurements using the known distance between threads on the specific implant that was used indicated a mean bone loss of 0.27 ± 0.68 mm around maxillary implants and 0.27 ± 0.67 mm around mandibular implants. Maxillary implants showed a statistically significant (SS) difference in bone loss on the mesial (0.20 mm) compared to the distal side (0.34 mm). In the mandibular group, there was an SS difference in bone loss around implants with wide (≥ 5 mm) and regular (< 5 mm) diameters. There was also an SS difference in bone loss in patients 50 years and older (0.28 mm) compared to patients younger than 50 (0.18 mm). In both groups, there were no SS differences in bone loss between machined- and rough-surface implants, men and women, single and splinted implants, nonsmokers and light/heavy smokers, or in patients with a penicillin allergy who were prescribed azithromycin as an alternate prophylactic antibiotic. All SS differences found in variables evaluated in the study were < 1.0 mm and therefore were considered clinically insignificant.