title: A 3-year post-loading report of a randomised controlled trial on the rehabilitation of posterior atrophic mandibles: short implants or longer implants in vertically augmented bone?
abstract: OBJECTIVE
  To evaluate whether 6.3 mm-long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles.
  
  
  METHODS
  Sixty partially edentulous patients having 7 to 8 mm of residual crestal height and at least 5.5 mm thickness measured on CT scans above the mandibular canal were randomised according to a parallel group design either to receive 1 to 3 submerged 6.3 mm-long implants or 9.3 mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional an organic bovine bone blocks covered by resorbable barriers. Grafts were left to heal for 5 months before implant placement. Four months later, provisional acrylic prostheses were delivered, and were then replaced after another 4 months by definitive metal-ceramic prostheses. Outcome measures were prosthesis and implant failures, complications, and radiographic peri-implant marginal bone level changes. All patients were followed up to 3 years after loading.
  
  
  RESULTS
  Four patients dropped out, two from each group. The augmentation procedure failed in two patients and only 6.3 mm-long implants could be inserted. There were no statistically significant differences for prosthesis and implant failures. Three prostheses could not be placed or had to be remade in the short implant group versus 4 prostheses in the augmented group. Two short implants failed versus 3 long implants, all in different patients. There were statistically significantly more complications in augmented patients (22 complications in 20 augmented patients versus 5 complications in 5 patients of the short implant group). Both groups gradually lost peri-implant bone in a statistically significant way at 4 months, and 1 and 3 years after loading. Three years after loading, patients of the short implant group lost an average of 1.24 mm of peri-implant bone compared with 1.76 mm in the long implant group. Short implants experienced statistically significantly less bone loss (0.52 mm; CI 95% 0.20 to 0.83, P = 0.002) than long implants.
  
  
  CONCLUSIONS
  When residual bone height over the mandibular canal is between 7 and 8 mm, 6.3 mm short implants could be an interesting alternative to vertical augmentation since the treatment is faster, cheaper and associated with less morbidity. Longer follow-ups are needed to confirm these results.
authors.affiliation: Department of Biomaterials, Goteborg University, Sweden.
authors.forename: Marco
authors.initials: M
authors.lastname: Esposito
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Cannizarro
authors.forename: Elisa
authors.initials: E
authors.lastname: Soardi
authors.forename: Gerardo
authors.initials: G
authors.lastname: Pellegrino
authors.forename: Roberto
authors.initials: R
authors.lastname: Pistilli
authors.forename: Pietro
authors.initials: P
authors.lastname: Felice
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D016301:Alveolar Bone Loss / Q000209:etiology; D000540:Alveolar Ridge Augmentation / Q000379:methods*; D001284:Atrophy; D001857:Bone Matrix / Q000637:transplantation; D018786:Bone Substitutes / Q000627:therapeutic use; D003094:Collagen; D003722:Dental Alloys / Q000737:chemistry; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000534:rehabilitation / Q000601:surgery*; D008297:Male; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D008567:Membranes, Artificial; D008875:Middle Aged; D008903:Minerals / Q000627:therapeutic use; D011183:Postoperative Complications; D014025:Titanium / Q000737:chemistry; D016896:Treatment Outcome
chemical_list: D000497:Alloys; C106416:Bio-Gide; C077540:Bio-Oss; D018786:Bone Substitutes; D003722:Dental Alloys; D015921:Dental Implants; D008567:Membranes, Artificial; D008903:Minerals; C031462:titanium alloy (TiAl6V4); D003094:Collagen; D014025:Titanium