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Impact of Abutment Geometry on Early Implant Marginal Bone Loss
TAKE-HOME MESSAGE
- In this randomized clinical trial designed to assess the impact of abutment width on early marginal bone loss (MBL), there was significantly less MBL observed adjacent to concave abutments compared with that adjacent to conventional cylindrical abutments at 6 months after loading. A loss of mean bone level occurred adjacent to cylindrical abutments, whereas an increase in average bone level occurred adjacent to concave abutments.
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Early bone loss is associated with longer term MBL and minimizing early MBL facilitates peri-implant health maintenance. Concave abutments present significantly less early MBL at 6 months post-loading than classical cylindrical abutments, which might be explained by narrowing of the prosthetic abutment leaving more space for peri-implant soft tissues.
abstract
This abstract is available on the publisher's site.
Access this abstract nowOBJECTIVES
The objective of this study was to analyze the impact of the abutment width on early marginal bone loss (MBL).
MATERIAL AND METHODS
A balanced, randomized, double-blind clinical trial with two parallel experimental arms was conducted without a control group. The arms were "cylindrical" abutment and "concave" abutment. Eighty hexagonal internal connection implants, each with a diameter of 4 × 10 mm, were placed in healed mature bone. The main variable was the peri-implant tissue stability, which was measured as MBL at 8 weeks and 6 months.
RESULTS
The final sample consisted of 77 implants that were placed in 25 patients. 38 (49.4%) were placed using the cylindrical abutment, and the other 39 (50.6%) were placed using the concave abutment. The early global MBL of -0.6 ± 0.7 mm in the cylindrical abutment group was significantly higher than it was in the concave abutment group, in which the early global MBL was -0.4 ± 0.6 mm (p = .030). The estimated effect size (ES) was negative for the cylindrical abutment (ES = -1.3730, CI -2.5919 to -0.1327; t-value = -2.4893; p = .0139), therefore implying a loss of mean bone level, and it was positive for the concave abutment (ES = 2.8231; CI: 1.4379 to 4.2083; t-value = 4.0957; p = .0002), therefore implying an increase in the average bone level.
CONCLUSIONS
The concave abutments presented significantly less early MBL at 6 months post-loading than classical cylindrical abutments did.
Additional Info
Impact of abutment geometry on early implant marginal bone loss. A double-blind, randomized, 6-month clinical trial
Clin Oral Implants Res 2022 Oct 01;33(10)1038-1048, M Pérez-Sayans, P Castelo-Baz, D Penarrocha-Oltra, F Seijas-Naya, M Conde-Amboage, JM Somoza-MartínFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The objective of this study was focused on the outcome of early marginal bone loss (MBL) post–abutment placement, which has been historically shown to pose as a risk factor for long-term bone loss around the fixture. One of the “hot topics” in the literature focused on implant therapy over the last several years has been on the “ailing” implant now that implant therapy is so pervasive in the population, with so many implant types, protocols, and restorative/functional considerations. Several variables have been identified and studied as outcomes' risk factors, including the surgical technique, fixture design, and abutment retention/connection type, with less attention given to the abutment design.
This study addressed the latter as a balanced, randomized, double-blinded clinical trial with two parallel experimental arms. Although the authors stated that there was no control group, their investigation design did have a control group (active control vs negative control). The main difference between the abutment designs was at the platform interface with a cylindrical design (active control, as this is a standard/conventional design) in comparison with a concave design (experimental group). The results showed a statistical difference between the two groups, with an early global MBL of −0.6 mm ± 0.7 mm for the cylindrical design versus −0.4 mm ± 0.6 mm for the concave abutment design at the 6-month insertion threshold.
The question that comes to mind when reading the results of this study is the difference between statistical significance and clinical significance. Although early MBL (6 months) may pose as a potential risk factor for long-term MBL, does an MBL of 0.2 mm make a clinically significant difference in long-term outcomes when comparing the abutment designs? This study does raise important questions regarding the periodontal tissue cuff around the abutment of bone-level implants with a viable biologic width as it pertains to the abutment design, which may provide some guidance for peri-implant health. There is precedent in the thinking of the benefits of a constricted platform connection with the advent of platform switching, which has been proven to be beneficial for implant therapy outcomes related to abutment design.