Background: The purpose of this study was to evaluate inter-implant bone crest height changes between immediate and non-immediate dental implants placed in the anterior maxillary region.

Methods: A retrospective study was conducted on consecutively treated patients requiring at least two adjacent implants in the anterior maxillary region that were placed in the same operation during 1994 to 2004. Files of 45 healthy patients reporting 200 implants were reviewed. Age, gender, smoking status, and implant characteristics (coating and dimensions) were recorded. Inter-implant bone measurements were taken on two panoramic radiographs from each patient: one after implant placement and the other at the last follow-up. The distance between adjacent implants was measured at the implant–abutment interface (implant platform).

Results: Overall, 130 inter-implant gaps were found. Follow-up ranged from 8 to 146 months. Two-tailed Pearson correlation tests revealed a negative correlation between inter-implant distance and bone loss (P = 0.036). Mean peak-crest bone loss for immediate implants was higher than for delayed implants (P = 0.026). There was more bone loss when hydroxyapatite (HA)-coated implants were used, although no statistical significance was observed. No statistically significant difference was found between the different locations in the anterior maxilla. No correlation was found between patient's age, smoking habits, and bone loss or between follow-up time and bone loss.

Conclusions: A negative correlation was found between inter-implant distance and bone loss at the inter-implant bone crest in the anterior maxillary region. Bone loss was small in this study cohort.