Core to cosmetic dentistry are the use of implants. Many other procedures require the cosmetic dentist to first do supportive implants.
Procedures used for single tooth implants, bridges, and fixed dentures:
An abutment appropriate for the function is chosen first. Custom abutments are often used for single teeth and bridgework. An impression is made of the top of the implant, the neighboring teeth and gums. The impression is sent to a lab where the crown and abutment are built together. The abutment is situated on the abutment and a screw is passed through the abutment to fasten it to an internal thread, called a lag-screw, on the implant. In some cases the abutment and implant are created as one piece or when a prefabricated abutment is used. Custom abutments may be hand-crafted, made as a cast metal piece or milled from metal or zirconia. All of these materials have comparable success rates.
The scaffolding that connects the abutment to the implant may be either buttressed (flat) or cone-shaped. In conical abutments, the abutment collar is situated firmly inside the implants, which provides a stronger joint between the implant and abutment, as well as a better barrier against bacterial invasion in the body of the implant. A narrowed abutment collar can help to improve the seal, in a method known as platform switching. Combining a conical fit with platform switching provides for somewhat improved long term periodontal conditions in comparison with buttressed abutments.
Regardless of the material or technique used on the abutment, an impression is taken of the abutment and the crown secured with cement. A variation on this procedure involved a crown and abutment that are constructed as one piece and the lag-screw passes through to fasten the one-piece structure to the implant’s internal thread. There seems to be no benefit for using cement versus screws in prosthetics. Screws are generally thought to be easier to maintain as well as making replacement of broken prosthetics easier. Cement is considered to be of higher esthetic value.
Methods used for removable prosthetics:
The methods used for removable prosthetics such as overdentures differ from the mothods used for fixed dentures. For bar overdentures, a small metal bar is fastened to the implants. The denture joined to the bar with attachments that do not allow the denture to move as long as it is in place. Ball overdentures use a ball and socket kind of attachment to connect the denture to the implant and minimize movement.
Supporting structures for removable dentures can be either custom crafted or stock abutments. For custom retainers, at least four implant fixtures are put into place and an impression of the implants is made. The impression is taken to a lab which custom builds a metal bar with attachments that will keep the denture firmly in place.
Retention of the prosthesis can be improved by creating multiple semi-precision attachments, such as small pins that can be passed through the denture into the bar. These attachments will minimize movement of the denture while ensuring it can still be removed by the wearer. Positioning the implants at such an angle as to evenly spread out force may be enough to hold a fixed denture in place. The cost and number of procedures needed to accomplish this are comparable to a fixed prosthetic.
The cosmetic dentist may also opt to use stock abutments to hold the dentures by employing a male-adaptor attached to the implant and a corresponding female adaptor in the denture. The most common types of these adaptors are the ball and socket type and a button type. These types of structures allow the denture to move, but still hold the denture securely enough to improve dental function for the wearer when compared to conventional dentures.In all of these adaptor types, the female end of the adaptor located in the denture will require occasional replacement, but most patients are satisfied with this type of prosthetic as a removable alternative.