Multi-level volumetric changes at immediate implant sites – A retrospective case-control study

Background

After a single-tooth extraction, remodelling processes are initiated and morphological changes occur in the alveolar bone. Immediate implant placement associated with the use of bone substitutes and connective tissue grafts seems to reduce the amount of resorption at peri-implant areas. Despite the advantages with the use of these techniques, it is difficult to predict with precision what is going to happen after immediate implant placement, since it involves hard and soft tissue volume changes.

Aim/Hypothesis

To evaluate the volumetric changes in hard and soft peri-implant tissues after flapless immediate implant placement in the aesthetic zone during the first year of treatment.

Material and Methods

Eleven patients treated with single-tooth maxillary implants (Osseospeed EV, AstraTech Implant System, Dentsply Implants) after a traumatic flapless tooth extraction, between 15 to 25, were included in this study. A previous CBCT exam confirmed the integrity of the buccal bone plate. The horizontal implant bone gap was filled with a xenograft bone substitute. Digital impressions were taken prior to extractions (T0), 1 month (T1), 4 months (T2) and 12 months (T3) after implant insertion. The obtained STL files were superimposed with computer software allowing to create a colour map that quantitatively analysed the three-dimensional variations occurred in the intervened areas and adjacent tissues. Variables such as the Buccal Volume (BV) and Total Volume (TV) representing the volume changes between T0 and the different postoperative follow-ups were computed. Mean values were compared using a non-parametric test and statistical significance was set at 0.05.

Results

Eleven patients (mean age 52.54 + - 11.92 years), were evaluated after a 12-month period. No complications occurred in all included patients and implant sites during the follow-up period. Statistical analysis could not found significant differences between mean values during the three different postoperative time periods (P = 0.717). During the first month of treatment (T0–T1) it was observed a volumetric variation of −34.41 mm³ on the buccal side and a total variation of −62.39 mm³. Between the first and the fourth month (T1–T2) a volumetric alteration of −4.05 mm³ on the facial aspect and a total alteration of −4.85 mm³ occurred. Finally, during the fourth month and the final postoperative follow-up (T2–T3) it was found a buccal volumetric variation of −4.10 mm³ and a total variation of −6.01 mm³.

Conclusion and Clinical Implications

Immediate implant insertion is a predictable treatment when a replacement of a missing tooth is required, although failed to prevent volumetric tissue loss on peri-implant areas. Whereas in the first month buccal and palatal alterations are similar, during T1–T2 and T2–T3 the most variations took place on the buccal side. The highest volumetric loss occurred during T0–T1, in contradiction with recent literature suggesting that the most variations occur during the first 4 months.