Influence of Crown/Implant Ratio on Marginal Bone Loss: Insights from a Systematic Review

Influence of Crown/Implant Ratio on Marginal Bone Loss: Insights from a Systematic Review


Dental implants are a cornerstone of modern restorative dentistry, offering solutions for missing teeth that enhance both functionality and aesthetics. 

However, the success and longevity of dental implants are influenced by various factors, including the crown/implant (C/I) ratio. 

This article delves into the systematic review by Garaicoa-Pazmiño et al. (2014), which explores the impact of the C/I ratio on marginal bone loss (MBL) around dental implants. Understanding these dynamics is crucial for clinicians aiming to optimize implant outcomes.

Crown/Implant Ratio: Definition and Importance

The crown/implant ratio refers to the proportion between the length of the prosthetic crown and the length of the dental implant. A high C/I ratio, often found in short implants (<10 mm), has raised concerns regarding its potential impact on MBL and implant stability. 

MBL is a critical parameter for implant success, as excessive bone loss can lead to implant failure.

Systematic Review and Meta-Analysis: Methodology

The systematic review by Garaicoa-Pazmiño et al. included an extensive search of three electronic databases (PubMed, Ovid MEDLINE, and Cochrane Central) and a manual search for relevant human trials with a minimum follow-up of six months. 

The analysis focused on studies examining the influence of the C/I ratio on peri-implant MBL, considering factors such as the type of implant, implant connection, and technical or biological complications.

    • Significant Association Between C/I Ratio and MBL:
      The review included 13 studies that met the inclusion criteria. A significant negative association between the C/I ratio and MBL was found (P = 0.012), indicating that a higher C/I ratio was linked to less MBL. 

      Clinical Implications:

    • This finding suggests that the mechanical advantage provided by a higher crown relative to the implant may contribute to reduced stress on the peri-implant bone.

    • The findings suggest that short implants with a high C/I ratio can be a viable option without increasing the risk of MBL. 


    • This is particularly relevant for patients with limited bone height where longer implants are not feasible.

    • Impact of Implant Design and Connection:
      The review found no statistically significant differences in MBL related to the type of implant connection (e.g., internal vs. external) or the observation period. This highlights that the C/I ratio’s influence on MBL is consistent across different implant designs and over time.


Clinical Recommendations

Based on the systematic review’s insights, several clinical recommendations can be made to optimize implant outcomes:

Pre-Surgical Planning:
Thorough evaluation of the patient’s bone structure and soft tissue condition is essential. Advanced imaging techniques, such as CBCT scans, can provide detailed information for accurate implant placement.

Selection of Implant Length and Diameter:
Short implants with a higher C/I ratio should be considered in cases with limited bone height. The choice of implant diameter should also be optimized to ensure primary stability and support the prosthetic load.

Prosthetic Considerations:
The design of the prosthetic crown should aim to distribute occlusal forces evenly. Custom abutments and precise prosthetic planning can help achieve optimal load distribution.

Post-Operative Care and Maintenance:
Regular follow-up appointments and professional cleanings are crucial to monitor peri-implant health and address any signs of complications early. 

Patient education on maintaining oral hygiene is also vital for long-term success.

Future Research Directions

While the systematic review provides valuable insights, further research is needed to explore the long-term effects of high C/I ratios on implant success and MBL. 

Prospective clinical trials with larger sample sizes and extended follow-up periods can help validate the current findings and refine clinical guidelines.

The systematic review by Garaicoa-Pazmiño et al. highlights the importance of the C/I ratio in influencing peri-implant marginal bone loss. Contrary to previous concerns, a higher C/I ratio does not necessarily lead to increased MBL. 

Instead, it may offer mechanical advantages that protect the peri-implant bone. By incorporating these findings into clinical practice, dental professionals can enhance the success rates of dental implants, even in challenging cases with limited bone height.

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