Implant Placement : result

It is important for the surgeon to understand that the final result will never be better than what they can establish when placing the implant as support for the prosthetic construction; so the implant should be considered the apical extension of the restoration, and the preferred design of the restoration (screwed or cemented) should dictate the surgical placement of the implant. The implant should be placed within the tooth position.

Horizontally, the long axis of the implant should be put within the future crown contour, usually in the alveolus of a monoradicular tooth or in the septum between the roots of biradic-ular teeth or multiradicular teeth, in such a way that the buccal aspect of the implant platform just touches an imaginary line between the incisal edges of the adjacent teeth.

Mesiodistally, there should be equal distances to the roots of the anterior and posterior teeth, and buccolingually towards the centric cusps of the antagonist teeth. Remaining buccal/palatal wall thickness must be at least 1 mm6.

If placement is too buccal, this often results in a dehiscence of the buccal bone plate, with gingival recession, and the esthetics will be compromised. If placement is too palatal, that produces periodontal, biomechanical and phonetic problems.

Vertically, placement is 2-3 mm from the cementoenamel junction (CEJ) of the neighboring teeth in order to hide the metal of the implant and abutment.

The distance from the implant platform to the gingival margin is referred to as "running room". Implant width, implant head, countersink and periodontium phenotype are factors to consider in order to create sufficient running room to compensate for the implant platform that has a smaller diameter than the cervix of the tooth it replaces. A gradual transition creates an esthetic and pleasing emergence profile. The wider the implant, the shorter the distance required to form a gradual emergence profile.

In general, the more apical the placement of the implant, the better the emergence profile; but locating the implant-abutment interface more apically means losing more crestal bone for establishing the peri-implant biological width. It is generally accepted that the crestal bone is reestablished 1.5 mm apical to the implant-abutment interface. This interface is called the "microgap". The apico-coronal position of the implant should provide a balance between health and esthetics.

The emergence profile and the location of the microgap are the two most important parameters affecting health and esthetics. The implant shoulder should be at 2-3 mm for two-stage implants, and 1-2 mm for one-stage implants, apical to the CEJ of the adjacent teeth without gingival recession.

If the implant is placed too deeply, incomplete gingival filling of the mesial and distal embrasures will show as unesthetic black triangles.

Periodontium phenotype also dictates placement of the implant in a slightly more palatal and apical position to reduce the chance of recession, to achieve a proper emergence profile, and to avoid a ridge lap restoration.