Bone level tapered implants used for immediate versus early implant placement and restored with all-ceramic crowns on titanium base abutments- preliminary 1-year results of an ongoing randomized controlled clinical trial: Implant survival and bone level changes

Background

The successful treatment with dental implants following an early placement approach (implant placement 4–8 weeks after tooth extraction) has been demonstrated in different clinical studies. However, there is an understandable wish of the patient to have a fixed reconstruction after tooth extraction as soon as possible. To achieve this goal, immediate implant placement has some advantages. In order to achieve a better primary stability of the implant, tapered implants had been proposed.

Aim/Hypothesis

The aim was to assess the clinical and radiographic outcome of a new, bone level tapered implant with a hydrophilic surface when inserted either following an immediate or early placement protocol and to analyze behavior of the implant stability quotient at 3 time-points and the aesthetic outcome.

Material and Methods

Patients in need of tooth extraction and replacement by a single implant in the anterior to premolar areas of their maxillae or mandibles were recruited. The patients were randomly assigned to either the immediate (n = 10) or the early placement group (n = 10). 4–6 weeks after implant placement, impression taking was performed. 8–10 weeks after surgery, the implants were fully loaded with the final crown. The implant stability quoting was measured at three different time-points (placement, impression and loading). The clinical and radiological outcomes were assessed 6 and 12 months after loading. Clinical parameters around the implants and the adjacent teeth such as plaque control record, probing depth (PD), bleeding on probing and the amount of keratinized mucosa at the buccal aspect were measured during final closure (1–3 weeks after loading) and at the follow-up examinations 6 and 12 months after loading. At these three visits, also the esthetic parameters were assessed.

Results

All 20 implants could be loaded according to the protocol within 8–10 weeks after implant placement. At the 12 months follow-up visit, all 20 implants were osseo-integrated and the survival rate was therefore 100%. The ISQ values of all 20 implants showed a trend towards a gradual increase from 69.6 (buccal) and 72.7 (mesial) directly after implant placement to 73.55 (buccal) and 76.2 (mesial) at impression taking and 75.95 (buccal) and 78.4 (mesial) at loading. During the follow-up visits, the mean distance from implant shoulder to the first bone-to-implant contact was 0.32 mm after 6 months and 0.35 mm after 12 months, respectively. At the 12-months examination, the mean bone loss in the immediate group was 0.55 mm and 0.18 mm in the early placement group. In both groups, a mean recession of 0.15 mm occurred during the observation time of 12 months after loading. In general, there was an improvement over time regarding the papilla fill index according to Jemt.

Conclusion and Clinical Implications

The short-term, preliminary data of this clinical study demonstrate that bone level tapered implants placed by means of both immediate and early implant placement protocols exhibit similar survival and success rates, changes in the crestal bone level and esthetic outcomes 12 months after loading. However, longer follow-up of the entire study cohort is necessary to confirm these preliminary findings.