Implants an introduction All-on-4
In the first of a series of articles, Kevin Lochhead looks at the history, and the pros and cons, of this method of dental implants
I
n recent years, All-on-4 has gathered considerable interest in the part of the dental community involved with dental implants. This
article, and those that follow, will explain where the term has arisen from, how the procedure differs from other techniques and the specific advantages and compro- mises to the patient that are necessary when electing to have this treatment option. Securing a full arch bridge with
four implants is not a new concept. The original Brånemark mandibular full arch implant protocol1,2 outlined positioning five parallel implants between the mandibular foramen to secure a screw-retained cast beam veneered with acrylic and resin teeth (figures 1 and 2). The original protocol adopted by the Brånemark clinic was later adapted to four implants. This treatment option (with or without immediate
loading) has for more than 30 years been the standard ‘fixed’ solution for the edentulous mandible when there is insufficient bone above the inferior dental canal for more poste- rior implants. The situation has been more challenging in the maxillae. Due to the increased incidence of implant failure in the maxillae, and more specifically the posterior maxillae where the bone has less volume and is less dense, the treatment protocol was for the use of six or eight implants (figure 3). Eight implants is by no means the maximum number of implants that can be used in the maxillae and in their drive to seek the best long-term solution, some clinicians have advocated using 12 to 14 implants and cemented-bonded restorations. As the number of implants
increases, other problems appear: there is a need for more bone volume to retain the implants,
ABOUT THE AUTHOR
This article is presented by Kevin Loch- head, specialist prosthodontist at Edinburgh Dental Special- ists. Surgical expertise by Professor Glen Lello, Prof Lars Sennerby, Mr Martin Paley and Mrs Gillian Ainsworth. All laboratory work was carried out by the team at Edinburgh Dental Implant Laboratory.
time for surgery and restorative phases increases significantly, costs increase and maintenance becomes more difficult. Research in dental implants and the introduction of surface modifications have seen a reduction in failure rates3, and CAD/ CAM technology being introduced for the fabrication of superstruc- tures4. As the confidence with dental
implant success has grown, there has been a drive to provide patients with the results they seek more quickly. The conventional approach to managing the maxillae may take a year to 18 months from initiation to completion, allowing for healing after extraction, implant integration, second stage surgery and restora- tion fabrication, all the while the patient having to wear a complete upper denture, which they hate. The challenge to reduce the
cost and the time involved started with immediate loading protocols,
Fig 1
Impression copings on five implants between mandibular foramen
Fig 2
Fixed cast beam and acrylic teeth on five implants
Fig 3
Eight implants in maxillae for fixed PMA restoration
38 Scottish Dental magazine
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