title: Stability of the bone-implant complex. Results of longitudinal testing to 60 months with the Periotest device on endosseous dental implants.
abstract: BACKGROUND
  Maintenance of the health and integrity of the bone-implant complex (osseointegration) has been shown to be essential for long term success of root-form, endosseous dental implants. If reliable clinical indicators of adequacy of the bone-implant complex existed, they could stimulate new and innovative early intervention research to arrest of reverse early deterioration of the bone-implant complex. In the absence of such indicators, this has been problematic. The Periotest may have the potential to provide this information by indirectly assessing the status of the bone-implant complex. However, little information is available that documents either the capability of the Periotest to reliably assess changes of the bone-implant complex or the "normal variations" in Periotest values (PTVs) for both HA-coated and non-coated implants.
  
  
  METHODS
  The purpose of this paper was to document changes in PTVs as influenced by various implant surfaces, implant designs, and bone densities. The mean PTVs recorded for each visit, for all implant types and bone densities, were combined to provide an overall average PTV (A-PTV). The changes in stability (PTVs) were analyzed using a generalized linear model (GLM) with repeated measures (Hotelling's Trace).
  
  
  RESULTS
  The A-PTV for all implants over all visits was -3.5. The mean PTVs ranged from -4.2 (SD = 2.4) at uncovering to -3.9 (SD = 2.9) at 60 months. All implants in bone qualities 1 and 2 (BQ-1 and BQ-2) became more stable over time, while those in bone quality 3 or 4 (BQ-3 and BQ-4) showed a slight decrease in stability. In BQ-1, the mean PTVs increased from -4.7 at uncovering to -4.9 at 60 months. A similar increase in stability occurred in BQ-2 (-4.1 at uncovering to -4.4 at 60 months). In BQ-3, the stability of the implants decreased over time (-3.6 at uncovering to -2.9 at 60 months), with similar changes recorded for BQ-4 (-2.5 at uncovering to -1.0 at 60 months). When comparing the stability of all HA-coated with all non-coated implants, the HA implants became less stable (-4.4 to -3.4) over time, while non-coated implants showed an improvement in stability (-3.5 to -4.5). The changes in stability found in BQ-1, BQ-2, and BQ-3 were similar, with HA implants becoming less stable and non-coated more stable. HA- and non-coated comparisons were not possible in BQ-4 since there were too few non-coated implants placed in this type of bone. The HA-coated screw showed a decrease in stability when compared to the non-coated screw.
  
  
  CONCLUSIONS
  Conclusions of the study are as follows: 1) PTVs are influenced by bone quality and surface coating of the implant; 2) the PTVs at the time of uncovering provide the best estimate of a clinically acceptable PTV for that bone-implant complex; 3) while the PTVs for any bone-implant complex may fluctuate +/- 1.0 around the uncovering PTV during routine healing and loading of the implant, a consistent shift toward a positive PTV that approaches "0" should be cause for concern that the bone-implant complex may be at risk of failure; 4) HA-coated implants became slightly less stable (more positive PTVs) over time, while the non-coated implants became more stable (more negative PTVs); and 5) until a "critical PTV" can be accurately identified, it is suggested that a consistent shift in recorded PTVs that exceeds the +3.0 value on the PTV scale should be viewed with concern for possible deterioration at the bone-implant complex.
authors.affiliation: Dental Implant Clinical Research Group, VA Medical Center, Northport, NY, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Truhlar
authors.forename: H F
authors.initials: HF
authors.lastname: Morris
authors.forename: S
authors.initials: S
authors.lastname: Ochi
mesh_terms: D000497:Alloys; D015519:Bone Density; D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D017886:Durapatite; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008334:Mandible / Q000473:pathology* / Q000601:surgery; D008437:Maxilla / Q000473:pathology* / Q000601:surgery; D016348:Osseointegration; D010517:Periodontics / Q000295:instrumentation; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium; D016896:Treatment Outcome; D014945:Wound Healing
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); D017886:Durapatite; D014025:Titanium