Effect of Crown to Implant Ratio and Anatomical Crown Length on Clinical Conditions in a Single Implant: A Retrospective Cohort Study.
OBJECTIVE
The aim of this retrospective cohort study was to evaluate the long-term influence of the crown-to-implant (C/I) ratio and anatomical crown length on clinical conditions around Astra single dental implants placed in the premolar and molar regions.


METHODS
Seventy-six subjects were selected from patients who had been treated with single Astra implants for replacement of missing premolars and molars. The peri-implant marginal bone level change was assessed 1 year after functional loading and 6 years after functional loading. To predict the peri-implant marginal bone level change using clinical and radiographic data, a multiple linear regression model was applied. The Wilcoxon rank sum test was used to analyze difference median in technical complications.


RESULTS
The C/I ratio and anatomical crown length were not associated with peri-implant marginal bone loss or changes in the bone level at 6 years (p = .48, p = .31). However, the modified plaque index, modified sulcus bleeding index, and smoking status influenced the peri-implant marginal bone loss (p < .05, r(2)  = 0.54). In addition, the patient with technical complication group did show significantly increased anatomical crown length (p < .05) CONCLUSIONS: The higher C/I ratio and anatomical crown length did not increase the risk of peri-implant marginal bone loss during 6 years of functional loading. In addition, higher anatomical crown lengths are associated with higher technical complications.
Department of Periodontology, Gangnam Severance Dental Hospital, College of Dentistry, Yonsei University, Seoul, Korea.
Shan-Pao
SP
Sun
Department of Periodontology, Gangnam Severance Dental Hospital, College of Dentistry, Yonsei University, Seoul, Korea.
Ik-Sang
IS
Moon
Department of Oral & Maxillofacial Surgery, Gangnam Severance Dental Hospital, College of Dentistry, Yonsei University, Seoul, Korea.
Kwang-Ho
KH
Park
Department of Periodontology, Gangnam Severance Dental Hospital, College of Dentistry, Yonsei University, Seoul, Korea.
Dong-Won
DW
Lee
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003442:Crowns; D015921:Dental Implants; D017267:Dental Prosthesis Design / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D015921:Dental Implants
crown-to-implant ratio; marginal bone loss; single implant