When restorative dentists are faced with a complex case containing multiple implants, they often rely on their laboratories to solve problems of parallelism, angulation, emergence profile and bucco-lingual and occlusal spacing.  Laboratories commonly construct custom abutments based on gold cast to prefabricated gold cylinders; there are several major problems with this approach.  Gold cylinders are expensive, and they are very time consuming, to wax, cast, and finish. Properly constructing an emergence profile below the gingeva is also a difficult challenge. In addition gold, while acceptable is not an ideal material for an abutment attached to a titanium fixture.  Gold over time tends to fatigue and deform. Gold also has much different thermal characteristics and modulus of elasticity. The strongest and most durable attachment interface would be between contiguous machined titanium surfaces.

Fortunately, there is a simpler more direct and less expensive method to handle these cases.  There are manufactures such as Titan Implants, which have recently brought to market well fitting machined titanium abutments with a wide range of collar heights and profile dimensions.  These new titanium abutments are so perfectly machined that they approach a "press fit", with no rotation and no wobble on the analog and fixtures, even prior to insertion of the central screw. (Fig.1) The following describes a technique, that is simple, highly cost effective and will result in the most long lasting and durable prosthetics:

First: the dentist must make an open tray impression containing transfer copings.(Fig 2) from this impression the lab constructs a tissue model of stone and rubber which accurately represents the orientation of the implants and tissue.

Second: the technician chooses the proper-machined titanium attachments for each site. The depth of tissue is then measured with a perio probe or by reading the depth markings on an implant locator rod [available from Titan Implants.]which can be screwed into the analogs. (Fig –3) From this measurement one millimeter is subtracted and the resulting number is the collar height of the attachment to be chosen.  The width of the attachment is then determined by estimating the final width requirements of the tooth being replaced.  In this case one premolar abutment with a five millimeter diameter profile and a four millimeter collar height along with two molar abutments with six millimeter diameter profiles and four millimeter collar height where chosen.(fig 4)

Third: the abutments are then tried on the model by sliding them down the implant locator rods, which have previously been screwed into the analogs (fig 5). Modifying the abutments for height, parallelism and angulation is a easy task since they can be slid on and off the analogs guided by the implant locators.(fig 6)  The collar height of the abutment can be modified by using the proper stones also available, from titan so that the collar margins are at least one millimeter below the crest of the gingeva.   (fig 7)   A complete kit is available from Titan Implants Inc. containing a special holder to firmly grasp the attachment, while modifying its shape. (fig 8)

Fourth: after the abutments have been properly modified the over casting can be constructed (fig 9a,b,c) .

The genius of this system lies in the over casting.  This gold alloy casting incorporates the proper emergence profile.  It is far easier to create an emergence profile collar on this over casting then it would be on abutments made from gold cylinders.  The over casting collar has its finishing line one half millimeter below the gingeva, and the porcelain can be finished to this line. The abutments, connected by light cure gel or duralay can then be screwed onto the fixtures by the dentist who can easily crack off this acrylic index. (Fig.10)

This technique allows the completed case to be delivered to the dentist in one or two visits saving valuable chair time and lab time for the technician.

Another advantage is that the dentist does not have to trim the gum back to create all the space necessary for the longer emergence profile that has to be placed on a gold cylinder abutment.

Eliminating gold castings and gold prefabricated gold cylinders saves well over $200 per abutment. The cost of titanium abutments is approximately $60.  This leads to a saving per abutments of $140, which can be passed on to the patient, and also decreases lab overhead.

Every effort must be made to decrease the cost and increase the durability, quality and strength of implant prosthesis, so that more dentists will be able to help more of their patients receive the benefits of implant dentistry.