Biological aspects as a rule for single implant placement. The 3A-2B rule: a clinical report

J Prosthodont. 2013 Oct;22(7):575-580. doi: 10.1111/jopr.12039. Epub 2013 Apr 1.


For an implant restoration to be both esthetically and functionally successful, the prosthodontist must conduct a thorough treatment plan and complete a prosthesis design. The prosthodontist must carefully calculate the space needed for the restoration and soft tissue in the restoration process. The restoration and soft tissue are affected by the three-dimensional (3D) position of the implant, as the implant's depth determines the ideal length of the crown. When determining the 3D position of the implant, the clinician must consider the biological aspects required to ensure the restoration's biological integration with the patient's hard and soft tissues. The restoration must be the first component considered in the treatment plan. In addition, the clinician must understand that the distance between the cervical contour (of the planned restoration) and the level of the bone will dictate how the surgical and prosthetic treatment plan is enacted. In this report, a novel Radiographic Biological Ruler© (with biological information) was used to help facilitate the treatment plan's analysis.

Keywords: 3A-2B rule; Radiographic Biological Ruler; biological rule; biological width; dental implants; esthetics; implant site development; pink esthetics; screw-retained single restorations; single restorations.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Alveolar Process / anatomy & histology
  • Anodontia / rehabilitation
  • Calibration
  • Crowns
  • Dental Arch / pathology
  • Dental Implantation, Endosseous / methods*
  • Dental Implants, Single-Tooth*
  • Dental Prosthesis Design
  • Follow-Up Studies
  • Humans
  • Imaging, Three-Dimensional / methods
  • Incisor / abnormalities
  • Male
  • Maxilla / pathology
  • Osseointegration / physiology
  • Patient Care Planning*
  • Periodontium / anatomy & histology
  • Tomography, X-Ray Computed / methods