Does using concave abutments improve 24-month outcomes of single posterior implants?

Area of Science:

• Dental Implantology
• Biomaterials Science
• Prosthodontics

Background:

• Marginal bone loss (MBL) around dental implants is a critical factor influencing long-term success.
• Abutment design, including shape and height, may impact peri-implant bone remodeling.
• Understanding these influences is crucial for optimizing implant restoration outcomes.

Purpose of the Study:

• To evaluate the influence of straight versus concave abutment shapes on marginal bone remodeling around dental implants over 24 months.
• To assess the impact of abutment height on marginal bone loss.
• To compare implant stability (ISQ) and periodontal indices (PD) between different abutment types.

Main Methods:

• A 24-month, split-mouth randomized clinical trial involving 30 patients (80 implants).
• Comparison of straight aesthetic antirotational abutments and concave antirotational abutments.
• Primary outcome: Implant Stability Quotient (ISQ); Secondary outcomes: Marginal Bone Loss (MBL) and Probing Depth (PD).

Main Results:

• No statistically significant difference in ISQ, PD, or bleeding scores between straight and concave abutments at 24 months.
• Initially, at 8 weeks post-placement, concave abutments showed significantly less MBL (0.18 mm) compared to straight abutments (0.54 mm).
• Linear mixed-effects models revealed that concave abutments generally led to less MBL, and greater abutment height was associated with reduced MBL.

Conclusions:

• Concave abutments did not demonstrate a significant long-term difference in MBL compared to straight abutments at 24 months.
• The early MBL difference observed was clinically insignificant by the end of the study.
• Abutment height appears to be an independent factor associated with reduced MBL, suggesting a protective effect.