J Periodontal Implant Sci.  2012 Dec;42(6):231-236.

Influence of crown-to-implant ratio on periimplant marginal bone loss in the posterior region: a five-year retrospective study

• Lee KJ
• Kim YG
• Park JW
• Lee JM
• Suh JY

Abstract

PURPOSE
The aim of this study was to evaluate the influence of the crown-to-implant (C/I) ratio on the change in marginal bone level around the implant and to determine the site-related factors influencing the relationship between the C/I ratio and periimplant marginal bone loss.
METHODS
A total of 259 implants from 175 patients were evaluated at a mean follow-up of five years. Implants were divided into two groups according to their C/I ratios: < or =1, and >1. Site-related factors having an influence on the relationship between C/I ratio and periimplant marginal bone loss were analyzed according to the implant location, implant diameter, implant manufacturer, prosthesis type, and guided bone regeneration (GBR) procedure.
RESULTS
It was found that 1) implants with a C/I ratio below 1 exhibited greater periimplant marginal bone loss than implants with a C/I ratio more than 1, 2) site-related factors had an effect on periimplant marginal bone loss, except for the implant system used, 3) the C/I ratio was the factor having more dominant influence on periimplant marginal bone loss, compared with implant diameter, prosthesis type, implant location, and GBR procedure, 4) implants with a C/I ratio below 1 showed greater periimplant marginal bone loss than implants with a C/I ratio greater than 1 in the maxilla, but not in the mandible, 5) and periimplant marginal bone loss was more affected by the implant system than the C/I ratio.
CONCLUSIONS
Within the limitations of this study, implants with a higher C/I ratio exhibited less marginal bone loss than implants with a lower C/I ratio in the posterior regions. The C/I ratio was a more dominant factor affecting periimplant marginal bone loss in the maxilla than the mandible. Meanwhile, the implant system was a more dominant factor influencing periimplant marginal bone loss than the C/I ratio.

Keyword

Alveolar bone loss; Dental implants; Follow-up studies

MeSH Terms

Alveolar Bone Loss
Bone Regeneration
Dental Implants
Follow-Up Studies
Humans
Mandible
Maxilla
Prostheses and Implants
Retrospective Studies
Dental Implants

Figure

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  Figure 1 Formula for calculation of crown-to-implant (C/I) ratio. mCH/mIL: mesial C/I ratio, dCH/dIL: distal C/I ratio. An average mesiodistal C/I ratio was obtained per implant restoration. mCH: mesial clinical crown height, mIL: mesial implant length, dCH: distal clinical crown height, dIL: distal implant length, FBIC: the first bone-to-implant contact.

• 

  Figure 2 Distribution of the implants according to their crown-to-implant ratio.

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