IMPLANT PROSTHETIC OPTIONS
Completely Edentulous Patients
At least three prosthetic implant options exist for the completely edentulous patient: They include (1) theimplant-‘ and tissue-supported overdenture, (2) the all implant-supported overdenture, and (3) the complete implant-supported fixed rehabilitation. II11P”lIIt· (/1/(1 tissue-supported overdcnture, Completely edentulous patients have the most difficulty with the mandibular denture. Long-time denture wearers with a progressively worsening lower denture fit may derive great benefit from an implant- and tissue-supported overdenture. For this type of prosthesis, most commonly two implants are placed in the mandibular symphysis area between the mental foramina. These implants are used to retain and support the lower denture. A bar may join these implants, and a clip housed in the denture retains the prosthesis (Fig. 14-~O). Implant- and issue supported overdentures require a very precise prosthetic technique. It is important that the retentive devices engage at the same time the posterior extensions contact 0thre tissue and at the same time the teeth meet in occlusion. Although this option is not the answer for all
patients, it provide s an economic alternative for the patient who only needs additional retention and stability for a lower denture.
All ‘implant-supported overdenture. For those patients requiring more retention and stability for an upper and lower denture, the all implant-supported overdenture may be the answer. For implants to support
the entire lad, it is recommended that a minimum of four implants be placed in the lower jaw and six implants In.the upper jaw, These implants are connected by.a more extensive bar design using multiple clips for
retention (Figs. 14-21 and 14-22 on page 317). This type of prosthesis can provide the advantages of minimal tis- . sue pressure, optimal access for hygiene, and optimal esthetics, because the denture covers all metalwork. In the maxilla this prosthesis can also have the additional advantages that the palate can be removed from the denture and that all air holes can be covered, which provides the patient with a better phonetic result. The disadvantage this prosthesis is that it is still a removable prosthesis
and must be removed for cleaning and maintenarice, which does not satisfy that patient who seeks implant treatment for the psychologic benefits of having a permanently-retained restoration. A further disadvantage
is that clip mechanisms wear over time and must be replaced.
Fixed detachable restoration. For those completely edentulous patients who require nonremovable restorations the two options are (1) a fixed porcelain-fused-tometal rehabilitation (Fig. 14-23 on page 318) or (2) a
hybrid prosthesis (Fig. 14-24 on page 318). The hybrid prosthesis is a cast framework with resin denture material and teeth processed to the framework. Both of these options require. a minimum’ of 5 implants in the
mandible and 6 implants in the maxilla. One major determining factor for selecting the appropriate option is the amount of bone loss. Complete-mouth fixed rehabilitation can only be made esthetically pleasing if minimal
bone loss has occurred’. This type of restoration is best suited for those patients who have recently lost their natural dentition. For patients who have moderate bone loss, the prosthesis must replace bone and soft tissue,
as well as teeth. In this case the hybrid prosthesis can best mimic soft
tissue replacement. The advantage to the completely fixed restoration (either the hybrid or fixed prosthesis) is that it is completely retained by the patient at all times. Patients derive the maximal psychologic benefit by having a restoration that is most like their natural teeth.Movement within the system is minimized, so the component parts tend to wear out less quickly. Potential disadvantages far the complete-mouth fixed rehabilitation is that implants must be very precisely placed, especially
in the maxillary anterior esthetic zone, to achieve the ideal esthetic result. The relative benefit to each restorative option can be described to the edentulous.
abutment in some systems. Healing cap scre.ws into abutment (right). Both types allow for soft tissue
healing after stage II surgery.
or supergingival.. (2) Fixed; this abutment is much like a conventional post and core. It is
screwed into the implants, has a prepared finish line, and receives a cemented restoration. (3) Angled:
available when .irnplant angles must be ·,f)”~::’;::d for esthetic or biomechanical reasons (4) Tapered:
can be used to make transition to restoration more gradual in larqer teeth. (5) Nonsegmented or direct:
used in areas of limited interarch distance or high esthetics demand. Restoration can be built directly on
implant, so no intervening ebutment is required. This direct restoration technique has been called the
UCLAabutment.
need not be changed on laboratory cast. (2) Transfer implant post: used if it is desirable to change
abutments on laboratory cast. This abutment should have at least one flat .side to correctly orient the
antirotational feature. (3) Pickup implant lmpression post: used to orient antirotational features or to
take impressions of very divergent implants.
model. Analog represents top of implant (left). Analog represents top of abutment (right).FIG. 14-16_.Laboratory analogs. laboratory analogs represent either implant or abutment in-laboratory
model. Analog represents top of implant (left). Analog represents top of abutment (right).
. orally, B, Impression post (upper left) unscrewed from mouth and
screwed onto abutment laboratory analog (lower left). C, Laboretory
analogs inverted into impression before pouring,
waxing sleeves, Plastic will be “burned-out” in th.e investment and
cast ‘in precious alloy, First plastic waxing sleeve is noted (arrow).
B, Five-implant framework cast in precious alloy. Previous location of
waxing sleeves is noted (arrow).
retained on abutment (right). Norsegmented crown retai~ed to
implant (left). The dotted lines..would represent the former position
of the waxing sleev
B, Plastic clip fabricated within denture a’l’Jddesigned to snap onto’
single gold bar (A) to help support and retain denture.
BOX 14-4
Patient Benefit Scale
1 No teeth
2 T Dentures
4 lrnplant and tissue overdenture
6 Allimplant-supported.overdenture
8 Fixed implant restoration
20 Natural teeth
Partially Edentulou.s Patients
MajOr advantages from implant support can be derived in the partially edentulous patient. The two· main indf:’ cations for implant restorations in this patient are (1).’ .the free-end distal extension when no terminal butmentis available and (2) a long edentulous. span. In both of these situations the conventional dental .treatment plan would include a removablepartial denture . .ln the short edentulous’ span (including Single-tooth’ restorations), the implant option is becoming a more popular .
enoree. This selection is often made because .natural abutments do not have to be prepared’ and impr-oved: access for hygiene can be realized. Ifthe implants are 10 rnm long or less, definite consideration should be given .to adding a third implant to support athree-unit fixed artial denture.
Free-end .distal’ extension. The implant dentist has two options in treating the patient missing terminal postenorabutments: (1) a single implant placed distal to the most Posterior natural abutment and (2) a fixed prosthesis
made to connect the implant and a natural tooth abutrrient. Alternatively two or more- implants can be placed posterior to the most distal natural tooth, ana an implant restoration can be fabricated (Figs. 14-25 and 14-26).
Single-tooth implant restorations. The use of single implants in restoring missing teeth is a very attractive option for the. patient and the dentist. This procedure requires a careful implant placement and precise control of all prosthetic components. Single-tooth restorations supported by implants O1ay be indicated in four situations:( l) patients-with otherwise lntactdentltion, (2) den- ·tition with spaces that would be more complicated to treat with conventional fixed prosthodontics, (3) distally miss- .iug teeth when cantilevers or removable partial dentures . are not Indicated.and (4)pa~ient desire for treatment that will most closely mimic the rrrissing natural tooth. ‘Ttre five requirerrrentsfcr single-tooth crown are as
follows: (Ij.esthencs, especially when a visible metal col- .Iar from the abutment is unacceptable: (2) antirotation to both avoid prosthetic component loosening and “allow
