Figure 1. Stock abutments on the implant analogs on the soft-tissue model.	Figure 2. Abutment Preparation Burs (Kit 4475 [KOMET USA]) with gross reduction carbides on the left, and finishing carbides on the right of the kit.

In today’s economic environment, laboratory costs can play a factor in acceptance of treatment. A difference of a few hundred dollars may be the decision point for some patients. Additionally, this also plays a factor when dealing with PPO insurance plans that often set the allowable fee at, or below, a UCLA or CAD/CAM abutment laboratory fee as charged to the practitioner. With this in mind, in-office custom abutment fabrication can provide a high-quality abutment at a lower cost, allowing the clinician to work within the patient’s financial and/or insurance boundaries. As a comparison, an in-office custom milled abutment will typically have a cost range between $75 and $100 (depending on the manufacturer). Whereas, the laboratory fee for a UCLA abutment is typically in the $250 range and a CAD/CAM can be more than $325 per abutment.
Before the introduction of the UCLA abutment, the only abutment available was a stock abutment, which either the dental laboratory technician or practitioner would mill; this was done chairside, or on a model creating a customized abutment. Today, this is still offered in some circumstances, and manufacturers have developed what are termed “milling abutments” to allow this to be offered in more situations. A milling abutment is essentially a solid abutment that has bulk added to it. This allows one to change angles as needed when creating a custom abutment, something that may not be possible with a standard stock abutment (Figure 1). Until recently, executing this process in the office was a challenge, as the rotary instruments we had at our disposal to fit our high-speed handpieces did not efficiently cut titanium. Friction-grip carbides in a titanium abutment adjustment kit (Figure 2). Abutments (kit 4475 [KOMET USA]) are now available specifically for shaping (black ring, golden shank) and finishing (red ring) titanium. This can be accomplished either intraorally, or extraorally. The author recommends that, unless minor customization is required, it is better to customize the abutments extraorally. This article will now address the steps for extraoral abutment customization using milling abutments.

 The milling abutment is placed into the soft-tissue model. Then the fixation screw is tightened to “finger tightness” so that the milling vibration does not cause the abutment to move on the model (Figures 4 to 6). The gross-reduction carbide (H847KRG.FG.018 [KOMET USA]) is used to reduce the occlusal surface. This is done so that the buccal and lingual edge of the abutment, which will become the cusp tips of the custom abutment, have sufficient clearance (2 mm is recommended), allowing the restoration be placed over it (Figure 7). When occlusal clearance is achieved, the gross-reduction football carbide (H379G.FG.023 [KOMET USA]) is then used to create buccal and lingual inclines on the occlusal surface (Figure 8). This is necessary so that the laboratory can create anatomy in the final crown and provide sufficient clearance. 

The tapered gross-reduction carbides (either the H856G.FG in 016/018 or H847KRG.FG in 016/018 [KOMET USA]) are used to reduce the interproximal to the level of the soft-tissue margin (Figure 9). This is also performed on the buccal and lingual surfaces (Figure 10). It is not necessary to perform a full reduction on these surfaces during this step, but it helps when you mark where the gingival margin is on the cast. The abutment(s) are marked with a permanent marker, indicating the buccal, and then the abutment is removed from the model. The soft-tissue material is removed from the cast, and the abutment is returned to the model, making sure it is positioned correctly with the buccal mark. The gross-reduction carbides are then used to reduce the circumferential surfaces, positioning the final margin approximately 0.5 mm apical to the mark created when the soft-tissue material was present. The benefit of working on the model is that it can be rotated in any direction and viewed from any angle so you can create the ideal preparation. Convergence of the preparation walls at approximately 6° should be the objective, giving the crown maximum retention to the abutment. 

The gross reduction carbides provide a rough surface, which will be difficult to capture in an impression because of surface tension between the impression material and the abutment’s surface. For this reason, the surface needs to have some finishing performed. Matching the gross-reduction carbides in the kit are titanium finishing carbides (H375R.FG.016/018, H336.FG.016/018, and H379.FG.023 [KOMET USA]). These are used to remove the rough marks on the titanium surface (Figure 11). 

The abutments are now ready for insertion into the patient (Figures 12 to 14). Provisional crowns may be fabricated on the abutments on the soft-tissue model, before the patient visit or on the soft-tissue model with the custom abutments on them. Both can be sent to the laboratory to have the final crowns created and delivered during the same appointment as the abutments. The impression heads and analog can be recycled, using them for subsequent patients after proper sterilization.