title: Biomechanical, Biologic, and Clinical Outcomes of Undersized Implant Surgical Preparation: A Systematic Review.
abstract: OBJECTIVE
  To compile the current evidence on biomechanical, biologic, and clinical outcomes of undersized surgical preparation protocols in dental implant surgery.
  
  
  METHODS
  An electronic search using three different databases (PubMed, Web of Science, and Cochrane Library) and a manual hand search were performed including in vitro, animal, and clinical studies published prior to October 2015. Studies in which an undersized drilling protocol was compared with a nonundersized drilling protocol were included.
  
  
  RESULTS
  From an initial selection of 1,655 titles, 29 studies met the inclusion criteria, including 14 biomechanical, 7 biologic, 6 biologic and biomechanical, and 2 clinical. Due to methodologic variation, meta-analysis was not performed. Several studies showed that implants inserted with an undersized drilling approach reached a significantly higher insertion torque value than conventional drilling in low-density substrates, while this effect is less evident if a thick cortical layer is present. Similar results in terms of boneto-implant contact (BIC) were achieved in the longer term between implants inserted with undersized and nonundersized protocols. Results in the short term were inconclusive. Clinical studies did not show negative outcomes for undersized drilling, although clinical evidence was sparse. No data are available on marginal bone loss.
  
  
  CONCLUSIONS
  From the biomechanical standpoint, an undersized drilling protocol is effective in increasing insertion torque in low-density bone. Biologic response in long-term healing after undersized implant placement is comparable to that in the nonundersized surgical drilling protocol. Clinical studies indicate that performing an undersized drilling protocol on low-density bone is a safe procedure; however, more extensive studies are needed to confirm these data.
authors.forename: Michele
authors.initials: M
authors.lastname: Stocchero
authors.forename: Marco
authors.initials: M
authors.lastname: Toia
authors.forename: Denis
authors.initials: D
authors.lastname: Cecchinato
authors.forename: Jonas P
authors.initials: JP
authors.lastname: Becktor
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
authors.forename: Ryo
authors.initials: R
authors.lastname: Jimbo
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D006801:Humans; D003765:Models, Dental; D013499:Surface Properties; D019415:Torque
chemical_list: D015921:Dental Implants