title: Clinical study on survival rate of short implants placed in the posterior mandibular region: resonance frequency analysis.
abstract: OBJECTIVE
  Short implants are increasingly used, but there is doubt about their performance being similar to that of regular implants. The aim of this study was to compare the mechanical stability of short implants vs. regular implants placed in the edentulous posterior mandible.
  
  
  METHODS
  Twenty-three patients received a total of 48 short implants (5 × 5.5 mm and 5 × 7 mm) and 42 regular implants (4 × 10 mm and 4 × 11.5 mm) in the posterior mandible. Patients who received short implants had <10 mm of bone height measured from the bone crest to the outer wall of the mandibular canal. Resonance frequency analysis (RFA) was performed at time intervals T0 (immediately after implant placement), T1 (after 15 days), T2 (after 30 days), T3 (after 60 days), and T4 (after 90 days).
  
  
  RESULTS
  The survival rate after 90 days was 87.5% for the short implants and 100% for regular implants (P < 0.05). There was no significant difference between the implants in time intervals T1, T2, T3, and T4. In T0, the RFA values of 5 × 5.5 implants were higher than values of 5 × 7 and 4 × 11.5 implants (P < 0.05). A total of six short implants that were placed in four patients were lost (three of 5 × 5.5 mm and three of 5 × 7 mm). Three lost implants started with high ISQ values, which progressively decreased. The other three lost implants started with a slightly lower ISQ value, which rose and then began to fall.
  
  
  CONCLUSIONS
  Survival rate of short implants after 90 days was lower than that of regular implants. However, short implants may be considered a reasonable alternative for rehabilitation of severely resorbed mandibles with reduced height, to avoid performing bone reconstruction before implant placement. Patients need to be aware of the reduced survival rate compared with regular implants before implant placement to avoid disappointments.
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, Dental School, University Center of Araraquara - UNIARA, São Paulo, Brazil.
authors.forename: Thallita P
authors.initials: TP
authors.lastname: Queiroz
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, Dental School, University Center of Araraquara - UNIARA, São Paulo, Brazil.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Aguiar
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, Dental School, University Center of Araraquara - UNIARA, São Paulo, Brazil.
authors.forename: Rogério
authors.initials: R
authors.lastname: Margonar
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, Dental School, University Center of Araraquara - UNIARA, São Paulo, Brazil.
authors.forename: Ana P
authors.initials: AP
authors.lastname: de Souza Faloni
authors.affiliation: Laboratory of Oral Cell Biology, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gruber
authors.affiliation: Department of Surgery and Integrated Clinic, Araçatuba Dental School, UNESP-Univ Estadual Paulista, Araçatuba, Brazil.
authors.forename: Eloá R
authors.initials: ER
authors.lastname: Luvizuto
mesh_terms: D000328:Adult; D000368:Aged; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants
keywords: atrophy; bone resorption; dental implants; mandible; short implants