Abutment and material selection for provisionalization, posterior zone
- Provisional placement, timing.
- Choices of abutment, and relationship to adjacent teeth or implants.
- Soft tissue management.
The first choice the clinician will be faced with once the implant is placed is to whether to immediate load the implant. This decisions is related to the implant stability, implant relationship to hard and soft tissue, esthetics, functional demands, occlusion, patient compliance, and whether the final or provisional abutment will be placed at the time of surgery. If the implant is stable as determined by torque values or other objective criteria, entertaining the placement of the provisional should be considered. If the stability is questionable then the implant should be allowed to undergo a submerged integration phase prior to proceeding.
There are a variety of times that a provisional may be placed during the treatment phase. The classic approach is following the osseointegration phase and following the healing of the soft tissue subsequent to placing the healing abutment. The healing abutment is removed and the soft tissue evaluated for depth, tissue type, and architecture. The connection to the implant can either be with an abutment or directly to the implant via the restoration. The abutment / restoration must incorporate a non rotating feature to the implant connection.
In the classic approach a either a provisional or final abutment may be placed. This is followed by titanium provisional cylinder cut to length (assuming the access opening is in a favorable position) and the tooth contours developed to satisfy the esthetic and functional needs. The tooth is then secured with the prosthetic screw. If the custom abutment lends itself to cement retention then the provisional is fabricated and luted to the abutment. This can also be accomplished by going directly to the implant platform with the provisional cylinder and following the same technique if a screw retained methodology is utilized.
Another option would be to have indexed the implant position at the time of stage 1 surgery and have fabricated a master cast. The provisional can then be fabricated in the laboratory and placed with the permanent abutment (if desired) and a provisional. The advantage to this technique is that it allows the creation of a custom abutment with CAD CAM technology and gives many more options for materials. In patients with thin gingival biotype this may be very helpful since it allows the use of ceramic materials that are less likely to show through the soft tissue. One additional advantage of placing the abutment at this time is the potential for some soft tissue attachment exists. Thus by placing the final abutment and not having disturb the soft tissue more consistent results are possible.
The ability to place the provisional has advantages. It will maintain the soft tissue profile in an immediate placement scenario. If it is an edentulous site the placement of the provisional will enable the molding of the soft tissue to begin. If a final abutment can be placed at the same time and the provisional be limited to just the tooth, this will result is the most stable soft tissue architecture. The possibility of achieving soft tissue “attachment” to the abutment is also maximized by taking this approach.
The materials available for the abutment are varied. With proper pre-surgical planning and design a custom abutment can be prefabricated along with the provisional and placed at the time of surgery. This can also be accomplished with stock abutments. Since esthetics are critical the ability to design anatomical abutments that replicate tooth preparations will maximize the soft tissue development. This can be accomplished with stock abutments and careful development of the provisional contours. There are a wide range of materials for this, and the clinician should have a thorough understanding of the one(s) being utilized. Surface contours, the ability to have a highly polished surface, strength under modified function, and esthetics need to balanced.
Soft Tissue Management
The restorative dentist needs to understand the relationship between the inter proximal contacts and proximity to adjacent implants / teeth to create the ideal papilla development. Careful adherence to these well documented principles will yield the desired esthetics assuming the implant placement is correctly oriented. The increasing acceptance of immediate placement and immediate load protocols has now allowed for the placement of the provisional at stage 1.
Digital Treatment Planning
The above mentioned options exist can be combined with the ability to plan precise implant placement relative to adjacent structures (NobelClinician); this approach enables the selection and design of the abutment prior to surgery. This enables the placement of the implant, abutment and provisional simultaneously. The main concern then shifts to controlling the forces on the complex during the osseointegration phase. Patients need to be counseled on diet and understand fully the restrictions they must follow. Especially in the posterior zone where occlusal contacts and forces are more significant diet restrictions are many times indicated. The importance of eliminating any excursive contacts that result in lateral forces cannot be overemphasized.
This is also dependent on the implant reaching acceptable torque values thus insuring initial stability and proper healing. It would be advisable to utilize screw retention in the provisional stage to minimize any complications with cement.