title: Comparison of stability between cylindrical and conical type mini-implants. Mechanical and histological properties.
abstract: OBJECTIVE
  To investigate the mechanical and histologic properties of conical compared with cylindrical shaped mini-implants in terms of the success rate.
  
  
  METHODS
  The samples consisted of cylindrical and conical groups, and commonly had 1.6 mm diameter and 6.0 mm length (Jeil Medical Corporation, Seoul, Korea) placed in beagle dogs. The mechanical study for analyzing maximum insertion torque (MIT), maximum removal torque (MRT), and torque ratio (TR; MRT/MIT) in Sawbones (Pacific Research Laboratories Inc, Vashon, Wash), and the animal study for resonance frequency analysis (RFA) and histomorphometric analysis (bone-to-implant contact and bone area) in two beagle dogs were done. All measurements were statistically evaluated using independent t-tests to determine any difference in MIT, MRT, TR, RFA, bone-to-implant contact (BIC), and bone area (BA) between the cylindrical group and conical group. A P value less than 0.05 was considered significant.
  
  
  RESULTS
  The conical group showed significantly higher MIT and MRT than the cylindrical group in the mechanical study. However, there was no significant difference in RFA, BIC, and BA between the two groups in the animal and histomorphometric studies.
  
  
  CONCLUSIONS
  Although the conical shaped mini-implant could induce tight contact to the adjacent bone tissue and might produce good primary stability, the conical shape may need modification of the thread structure and insertion technique to reduce the excessive insertion torque while maintaining the high resistance to removal.
authors.affiliation: Department of Dentistry, Seoul National University Bundang Hospital, Seoul, Korea.
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Kim
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Baek
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Kim
authors.forename: Young-Il
authors.initials: YI
authors.lastname: Chang
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D004285:Dogs; D005260:Female; D008297:Male; D008904:Miniaturization; D016348:Osseointegration; D019415:Torque; D014732:Vibration
chemical_list: D015921:Dental Implants