title: Long-term follow-up on hydroxylapatite-coated cylindrical dental implants: a comparison between developmental and recent periods.
abstract: OBJECTIVE
  To compare success rates for dental implants placed from 1985 through 1988 and from 1989 through 1991, and to investigate the factors associated with success or failure.
  
  
  METHODS
  All hydroxylapatite-coated cylindrical implants placed from 1985 through 1991 were followed yearly. Lifetable survival analyses compared implant success for a "developmental period" from 1985 through 1988 (4 to 8 years follow-up) and a "recent period" from 1989 through 1991 (1 to 4 years follow-up). Reasons for success or failure, time from implant placement to removal related to failure reason, outcome after implant removal, and a morbidity analysis are included.
  
  
  RESULTS
  The 7 to 8-year cumulative success rate for all implants placed in the developmental period (maxilla and mandible combined) was 86.5%; it was 84.2% for all maxillary implants and 87.5% for all mandibular implants. The cumulative success rate for all implants placed in the recent period was 97.5%; it was 97.5% for all maxillary implants and 97.6% for all mandibular implants. The difference between the two periods was statistically significant only for the anterior maxilla. Regression analysis on the interval success rates indicates that interval failure did not follow a linear relationship with time. The most common reasons associated with failure were lack of keratinized gingiva, poor oral hygiene, mechanical overload, and malposition.
  
  
  CONCLUSIONS
  Comparison with previously reported cumulative success rates indicated learning curve experiences comparable with other implant systems. Improvements in hardware, surgical and prosthetic techniques, and patient selection have led to an improvement in success rates with the recent period implants.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Louisiana State University School of Dentistry, New Orleans 70119.
authors.forename: M S
authors.initials: MS
authors.lastname: Block
authors.forename: J N
authors.initials: JN
authors.lastname: Kent
mesh_terms: D001862:Bone Resorption / Q000209:etiology; D003758:Dental Implantation, Endosseous / Q000009:adverse effects / Q000706:statistics & numerical data*; D017267:Dental Prosthesis Design; D017886:Durapatite; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015993:Life Tables; D008297:Male; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008437:Maxilla / Q000473:pathology / Q000601:surgery; D009910:Oral Hygiene; D010519:Periodontium / Q000473:pathology; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013499:Surface Properties; D016019:Survival Analysis; D013997:Time Factors; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D017886:Durapatite