title: Stimulation of directed bone growth at oxidized titanium implants by macroscopic grooves: an in vivo study.
abstract: BACKGROUND
  The influence of thread design at the millimeter level and surface topography at the micrometer level on bone integration and the stability of dental implants have been studied extensively. However, less is known about the influence of implant structures in the range of 50 to 200 microm.
  
  
  OBJECTIVE
  The present in vivo investigation was undertaken to study if bone formation and implant stability were influenced by 110 (S1) and 200 (S3) microm-wide and 70 microm-deep grooves positioned at a thread flank of oxidized titanium implants.
  
  
  METHODS
  Eighteen rabbits and oxidized titanium implants (3.75 mm in diameter and 7 mm long) were used in the study. Nine rabbits received three control implants and three test implants with a 110 microm-wide groove added to one thread flank. The remaining nine rabbits received three control implants and three test implants with a 200 microm-wide groove. The animals were followed for 6 weeks. Removal torque (RTQ) tests were applied to two of the implants in each leg. The remaining implant per leg was retrieved for histology. The degree of bone fill within the grooves and corresponding bone formation at the opposing surfaces, the bone area within the threads, and the degree of bone-implant contact were calculated for each implant.
  
  
  RESULTS
  The histologic analyses revealed an affinity for bone formation within the grooves. The RTQ tests showed that the peak RTQ was approximately 30% higher for the S1 implants compared with control implants without a groove. The difference was statistically significant (p < .05) for tibial and pooled implants. A similar but smaller and not statistically significant effect, approximately 8%, was measured for the S3 implants. The histomorphometric measurements confirmed the observed affinity of bone for the grooves. For S1 implants, 78.7 +/- 15.8% of the grooves were filled with bone, whereas only 46.2 +/- 27% of the corresponding flank surface showed the presence of bone (p < .05). The corresponding figures for S3 and control implants were 72.7 +/- 25.1% and 48.5 +/- 13.6%, respectively (p < .05). The degrees of bone-implant contact and bone area within the threads were similar for test and control implants.
  
  
  CONCLUSIONS
  It is concluded that 110 and 200 microm-wide and 70 microm-deep grooves at oxidized implant surfaces stimulated bone to preferentially form within and along the groove in the rabbit model. The 110 microm-wide groove was shown to increase the resistance to shear forces significantly. It is suggested that implants with such a groove may be one way to optimize implant stability in suboptimal clinical conditions.
authors.affiliation: Nobel Biocare AB, Göteborg, Sweden. jan.hall@nobelbiocare.com
authors.forename: Jan
authors.initials: J
authors.lastname: Hall
authors.forename: Patricia
authors.initials: P
authors.lastname: Miranda-Burgos
authors.forename: Lars
authors.initials: L
authors.lastname: Sennerby
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D020878:Device Removal; D005260:Female; D005269:Femur; D020007:Implants, Experimental; D016348:Osseointegration / Q000502:physiology*; D011817:Rabbits; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013977:Tibia; D014025:Titanium; D019415:Torque
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; C009495:titanium dioxide; D014025:Titanium