title: Mechanical versus biological stability of immediate and delayed implant placement using resonance frequency analysis.
abstract: OBJECTIVE
  The purpose was to objectively measure the stability of immediately placed implants compared with implants placed at healed sites using implant stability quotient (ISQ) values obtained by resonance frequency analysis.
  
  
  METHODS
  Data were collected from 137 Nobel Replace Tapered Groovy Implants placed in 85 patients 19 to 93 years old. All implants were placed by the same surgeon from May 2007 to October 2011. Forty-one implants were placed immediately after extraction with MasterGraft bone grafting material and 96 were placed in healed sites with no grafting material. ISQ values obtained by the Osstell ISQ System were recorded at the time of implant placement and at a subsequent follow-up appointment (T2). T2 was split into 2- to 3-month and 4- to 6-month groups depending on when their follow-up ISQ values were obtained. Data were analyzed using simple linear regression.
  
  
  RESULTS
  Implants placed in healed sites had higher average ISQ values at implant placement compared with immediately placed implants; however, mean ISQ values in the 2 immediate implant groups exceeded the ISQ threshold of 65. Immediately placed implants in the 2- to 3-month and 4- to 6-month groups had average ISQ values of 65.60 and 68.65, respectively, whereas implants placed in healed sites had averages of 76.73 (2- to 3-month group) and 71.23 (4- to 6-month group). These differences were statistically significant (P < .05). At subsequent follow-up appointments, implants placed in healed sites had higher mean ISQ values. Implants in healed sites had ISQ averages of 79.58 (2- to 3-month group) and 77.31 (4- to 6-month group), whereas immediately placed implants had averages of 73.88 and 70.14. These differences were statistically significant (P < .05). Moreover, these mean ISQ values in immediate implants exceeded the ISQ threshold of 65.
  
  
  CONCLUSIONS
  Although mean ISQ values of immediately placed implants are lower than those of delayed implants at implant placement and follow-up appointments, immediate implant mean ISQ values consistently remain higher than the clinically successful ISQ threshold of 65 throughout the osseointegration process. These results support the immediate placement of implants in extraction sockets under favorable conditions.
authors.affiliation: Dental Student, UCLA School of Dentistry, Los Angeles, CA.
authors.forename: Mark
authors.initials: M
authors.lastname: Rowan
authors.affiliation: Dental Student, UCLA School of Dentistry, Los Angeles, CA.
authors.forename: David
authors.initials: D
authors.lastname: Lee
authors.affiliation: Assistant Clinical Professor, Dental Implant Center, UCLA School of Dentistry, Los Angeles, CA.
authors.forename: Joan
authors.initials: J
authors.lastname: Pi-Anfruns
authors.affiliation: Dental Student, UCLA School of Dentistry, Los Angeles, CA.
authors.forename: Parker
authors.initials: P
authors.lastname: Shiffler
authors.affiliation: Professor, Department of Oral and Maxillofacial Surgery, UCLA School of Dentistry, Los Angeles, CA.
authors.forename: Tara
authors.initials: T
authors.lastname: Aghaloo
authors.affiliation: Nobel Biocare Endowed Chair, UCLA School of Dentistry, Los Angeles, CA. Electronic address: drmoy@titaniumimplant.com.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Moy
mesh_terms: D000328:Adult; D000368:Aged; D016025:Bone Transplantation; D015921:Dental Implants; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D015921:Dental Implants