title: Does Length, Diameter, or Bone Quality Affect Primary and Secondary Stability in Self-Tapping Dental Implants?
abstract: OBJECTIVE
  Implant stability is a clinically valuable measurement of the strength of implant anchorage in the bone during placement and in the post-osseointegration period. This study aimed to determine 1) the effect of implant diameter and length and bone quality on measurements of primary and secondary stability (insertion torque [IT] and implant stability quotient [ISQ]), 2) the correlation between IT and primary and secondary ISQ, and 3) differences in ISQ in the post-osseointegration period (secondary stability) compared with immediate post-placement (primary) stability.
  
  
  METHODS
  In this longitudinal clinical study, titanium self-tapping implants were inserted in edentulous patients. The implants were grouped according to 3 independent variables: length (10 and 11.5 mm), diameter (3.75 and 4.25 mm), and bone quality (Lekholm and Zarb classification) to analyze primary and secondary implant stability (outcome variables). Statistical analyses were performed using the Student t test for paired data, 1-way analysis of variance, and the Tukey procedure for multiple pairwise comparisons.
  
  
  RESULTS
  Data were collected on 88 self-tapping implants inserted in 63 partially edentulous patients. IT and implant stability were affected by diameter (3.75-mm implants, 26.5-N/cm IT and 74.0 ISQ; 4.25-mm implants, 33.8-N/cm IT and 77.0 ISQ) and bone type (type 1 + 2, 34.86-N/cm IT and 77.4 ISQ; type 3, 27.09-N/cm IT and 75.6 ISQ; type 4, 20.63-N/cm IT and 70.5 ISQ; P < .01 for all comparisons). Secondary ISQ was affected by diameter only (77.41 for 3.75- vs 75.51 for 4.25-mm implants). IT correlated with primary ISQ (R = 0.56; P < .01), although no clear correlation with secondary stability was found.
  
  
  CONCLUSIONS
  IT and primary ISQ in self-tapping implants differed in patients with different bone quality and implant diameter but did not differ between the 2 implant lengths compared in this study. Secondary stability was not substantially affected by any of these factors. Although IT was closely related to primary ISQ, it was unrelated to secondary ISQ. Very high primary ISQ values tended to decrease, whereas intermediate and low values tended to increase, in the transition to secondary stability.
authors.affiliation: Doctor in Dental Surgery and Part-Time Professor, Department of Prosthetic Dentistry, School of Dentistry, Complutense University of Madrid, Madrid, Spain. Electronic address: mgpolo@odon.ucm.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gómez-Polo
authors.affiliation: Doctor in Dental Surgery and Assistant Professor, Department of Prosthetic Dentistry, School of Dentistry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Ortega
authors.affiliation: Doctor in Dental Surgery and Part-Time Professor, Department of Surgery, Medicine School, University of Salamanca, Salamanca, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gómez-Polo
authors.affiliation: Doctor in Dental Surgery and Assistant Professor, Department of Prosthetic Dentistry, School of Dentistry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Martín
authors.affiliation: Medicine Doctor and Full-Time Professor, Department of Prosthetic Dentistry, School of Dentistry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Celemín
authors.affiliation: Medicine Doctor and Full-Time Professor, Department of Prosthetic Dentistry, School of Dentistry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Del Río
mesh_terms: D016301:Alveolar Bone Loss / Q000145:classification; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D005260:Female; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000534:rehabilitation; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D014025:Titanium; D019415:Torque; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants; D014025:Titanium