Factors influencing ridge alterations following immediate implant placement into extraction sockets

To identify factors that may influence ridge alterations occurring at the buccal aspect of the extraction site following immediate implant placement.

In 93 subjects, single-tooth implants were placed immediately into extraction sockets in the maxilla (tooth locations 15-25). A series of measurements describing the extraction site were made immediately after implant installation and at re-entry, 16 weeks later. The implant sites were stratified according to four factors: (i) implant location (anterior/posterior), (ii) cause of tooth extraction (periodontitis/non-periodontitis), (iii) thickness of the buccal bone walls (< or = 1 or > 1 mm) and (iv) the dimension of the horizontal buccal gap (< or = 1 or > 1 mm).

(i) The location where the implant was placed (anterior/posterior) as well as (ii) the thickness of the buccal bone crest and (iii) the size of the horizontal buccal gap significantly influenced the amount of hard tissue alteration that occurred during a 4-month period of healing. At implant sites in the premolar segment, the fill of the horizontal gap was more pronounced than in the incisor-canine segment, while the vertical crest reduction was significantly smaller. Furthermore, at sites where the buccal bone wall was thick (>1 mm) and where the horizontal gap was large (>1 mm), the degree of gap fill was substantial.

The thickness of the buccal bone wall as well as the dimension of the horizontal gap influenced the hard tissue alterations that occur following immediate implant placement into extraction sockets.