All-on-4

The term All-on-4 refers to "all" teeth being supported "on four" dental implants, a surgical and technique prosthodontics procedure[1][2] for total rehabilitation of the edentulous patient or for patients with badly broken down teeth, decayed teeth or compromised teeth due to gum disease. It consists of the rehabilitation of either edentulous or dentate maxilla and/or mandible with fixed prosthesis by placing four implants in the anterior maxilla, where bone density is higher. The four implants support a fixed prosthesis with 10 to 14 teeth and it is placed immediately, typically within 24 hours of surgery.

Implant manufacturer Nobel Biocare was among the first to identify the evolution of the All-on-4 technique as a potential valid and cost-effective alternative to conventional implant techniques, and funded studies by Portuguese dentist Paulo Maló[3] to determine the efficacy of this approach. During this time this technique was also used by various other clinicians around the world.

All-on-4 is not an invention, but rather a treatment technique that has evolved over time and has the following features:

  • four dental implants to support a full fixed bridge (documented since 1977[4])
  • the use of angulated implants in the back to overcome bony deficiencies or anatomical structures (documented since 1990[5])
  • immediate loading (documented since 1990[6])

The All-on-4 treatment concept is a prosthodontic procedure (i.e replacement of missing teeth) that provides a permanent, screw-retained, same-day replacement for the entire upper and / or lower set of teeth with a bridge or denture. The procedure is best for patients with significant tooth loss or decay and for people whose bone loss in the jaw area prevents them from getting conventionally oriented (vertical) dental implants. Often, tooth loss is accompanied by loss of the jaw bone which poses the problem of reconstruction of the jaw bone requiring bone grafting. The All-on-4 technique takes advantage of the dense bone that remains in the front part of the jaws and by placing the two posterior implants on an angle to avoid the sinus cavities in the upper jaw and the nerve canal in the lower jaw. For the implementation to be successful a careful analysis of the bone structure needs to be made. The most ideal way to evaluate the bone is by a CBCT scan. The All-on-4 protocol is for at least four implants to be placed in a jaw. The back implants are typically angled approximately 30 to 45 degrees from the biting plane. The implant is placed in front of the maxillary sinus in the upper jaw (maxilla) and in front of the mental nerve in the lower jaw (mandible). The head of the implant emerges in approximately the second premolar position. This will allow a molar tooth to be cantilevered posterior resulting in a denture or bridge with approximately 12 teeth.[7]

  • This image shows how Nobel Biocare's All-on-4 solution works.

References
  1. Patzelt SB, Bahat O, Reynolds MA, Strub JR (April 2013). "The All-on-Four Treatment Concept: A Systematic Review". Clin Implant Dent Relat Res. 16: 836–855. doi:10.1111/cid.12068. PMID 23560986.
  2. Zhao X, DI P, Lin Y, Li JH, Qiu LX, Luo J, Cui HY (October 2014). "Implanting the edentulous jaws with "All-on-4" immediate reconstruction: a preliminary clinical observation". Beijing Da Xue Xue Bao. 46: 720–6. PMID 25331394.
  3. Maló, Paulo; Rangert, Bo; Nobre, Miguel (2003). "'All-on-Four' Immediate-Function Concept with Brånemark System Implants for Completely Edentulous Mandibles: A Retrospective Clinical Study". Clinical Implant Dentistry and Related Research. 5: 2–9. doi:10.1111/j.1708-8208.2003.tb00010.x. PMID 12691645.
  4. Branemark, Per-Ingvar (1977). Osseointegrated Implants in the Treatment of the Edentulous Jaw. Sweden: Almquivist & Weksell International. pp. 79, 81, 83. ISBN 91-22-00128-X.
  5. Kallus, T (Spring 1990). "Clinical evaluation of angulated abutments for the Brånemark system: a pilot study". Int J Oral Maxillofac Implants. 5: 39–45. PMID 2202668.
  6. Lefkove, MD (1990). "Immediate loading of cylinder implants with overdentures in the mandibular symphysis: the titanium plasma-sprayed screw technique". J Oral Implantol. 16: 265–71. PMID 2098572.
  7. "Dental implants guide". Friday, May 15, 2020
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