Zygoma Implant

ZYGOMA ZYGOMA IMPLANTIMPLANT

By:Cortey, Philline

Espineli, ShermaneRobles, Kristina

What is Dental Implant?What is Dental Implant?

a replacement for the root or roots of a tooth.

dental implants are secured in the mandible and are not visible once surgically placed.

they are used to secure crowns bridgework or dentures by a variety of means.

they are made of titanium, which is lightweight, strong and biocompatible

titanium and titanium alloys are the most widely used metals in both dental and other bone implants.

dental implants have the highest success rate of any implanted surgical device.

History of Dental ImplantsHistory of Dental Implants In 1952 the Swedish

orthopaedic surgeon, P I Brånemark whilst conducting research into the healing and regeneration patterns of bone tissue, accidentally discovered that bone had that when pure titanium comes into direct contact with the living bone tissue, the two literally grow together to form a permanent biological adhesion.

He named this phenomenon “osseointegration".

Over the next fourteen years Brånemark published many studies on the use of titanium in dental implantology.

To the present day over 7 million Brånemark System implants have now been placed and hundreds of other companies produce dental implants.

The majority of dental implants currently available are shaped like small screws, with either tapered or parallel sides.

Types of Dental Implant Types of Dental Implant ProceduresProcedures

Three types of dental implants:

Root Form Dental Implant This screw type implant is shaped like the root of a tooth. This is the most commonly used implant and is used where there is plenty of width and depth to your mandible.

Plate Form Dental Implant◦ If your jawbone is too narrow for bone grafting,

a Plate Form implant is placed into your mandible.

• Subperiosteal Dental Implants- If there's not enough bone

width or height for the Root Form or Plate Form implants, the Subperiosteal implant is recommended.

- The Subperiosteal implant is custom made to rest on top of your jawbone and under your gums like the Plate Form implant, but the Subperiosteal implant is placed through one of two special methods.

So what’s NEW?So what’s NEW?

Dental implants have always been more sensitive in the maxilla than in the mandible. This situation becomes undesirable when the maxilla is severely resorbed and atrophic.

Studies highlight the zygomatic bone as a suitable anatomical structure for placement of dental implants as it cross four cortical bones.

Zygomatic implants are long screw shaped implants developed as an alternative to bone grafting and sinus augmentation.

Severely resorbed maxillae presents a complex problem. Lack of internal osseous stimulation results in continued resorption of an atrophic edentulous maxilla.

In such patients conventional implant treatment cannot be performed because of:1. Extensive bone resorption2.Pneumatization of sinus

ZYGOMA IMPLANTZYGOMA IMPLANT

In 1999 Dr. Per-Ingvar Brånemark and colleagues introduced the zygoma implant (P-I Brånemark, personal communication,1999). ◦ In their initial study over a 10-year period, 110 implants

were placed. Each patient had an additional two to four conventional implants placed in the anterior maxilla, which was restored with cross arch stabilization.

◦ Of the zygoma fixtures placed and restored in the initial study, only two were lost in the first year of occlusal loading, and three failed in the subsequent 8 years for a long-term success rate of > 95%.


It has provided a viable alternative for treatment of patients with extreme resorption of the edentulous maxilla or large pneumatized maxillary sinuses.

It is an extended-length (30–52.5 mm) machined titanium fixture that is placed through the crestal (slightly palatal) aspect of the resorbed posterior maxilla transantrally into the compact bone of the zygoma.


Four Osseous Cortices1. At the ridge crest2. The sinus floor3. The roof of the maxillary sinus4. The superior border of the zygoma


The zygoma implant provides posterior maxillary anchorage when the existing osseous structures do not allow standard implant placement.

The alternative in this situation includes bone graft augmentation (sinus lifts and onlay grafts) with their attendant costs, discomfort, prolonged treatment times, and higher complication rates.


It suggested in the following circumstances:◦ When full maxillary edentulism is accompanied by

advanced posterior resorption that would otherwise require grafting. At least two and preferably four anterior standard implants are needed in combination with bilateral zygoma implants.

◦ In partial or incomplete maxillectomy patients when additional implants can be placed in other sites such as the piriform sinus, orbital rims, palatal shelves, or pterygoid plates to support cross-arch stabilization.

INDICATIONSINDICATIONS1. Insufficient bone volume for

placement of regular implants posterior to canine

2. When there is contraindication for harvesting iliac crest bone graft

3. Systemic disease with atrophy of posterior maxilla like ectodermal dysplasia, cleft palate

4. Reconstruction of maxillary defects following tumor resection, nasal reconstruction

CONTRAINDICATIONSCONTRAINDICATIONS1. Same as for conventional implants2. Presence of local infection3. Systemic compromise4. Sinus disease

Two specific situations:Where adequate maxillary bone exists for

implant placement in numbersand positions to support a prosthetic appliance, the zygoma implant is not needed.

Where there is not enough premaxillary support for at least two stable implants with good potential longevity.


Complications:most significant complication: loss of the implant

A B C

A. An impression coping has been attached to the zygoma implant at the final impression appointment.

B. It was noted that there was rotational instability of this fixture with movement of the coping.

C. The implant was removed without resistance. There was no sign of bone adherence to any of the implant surface.


Interim therapy may include the use of a provisional restoration on the remaining integrated implants but should not include a cantilever extension on the affected side

Radiographic ExaminationRadiographic Examination

The radiographic examination of the resorbed frontal alveolar bone f the upper jaw is recommended.

1. Panoramic image2. Intra oral radiographs3. Lateral cephalogram 4. Tomography or CT

Scan

Presurgical Prosthetic Presurgical Prosthetic ConsiderationConsideration

Presurgical prosthetic examination and evaluation should include:◦ Facial profile and contours◦ Parafunctional habits◦ Horizontal and vertical jaw relations◦ Occlusal plane orientation◦ Occlusal relationships◦ Status of the oppsing dentition

Surgical proceduresSurgical procedures

Px is premedicated with 2 gms of amoxicillin 1 hr prior to the surgery

The px is sedated and draped, and the administratin of a local anesthetic agent is carried out.

Vestibular infiltratin and greater palatine block are administered

Also bilateral IAN Block is important

Surgical proceduresSurgical procedures

Using a small-gauge needle, bilateral transcutaneous infiltration of the temporal areas over the zygomatic body and zygomatic notch is also administered

Incision is standard Le-fort I incision, to obtain coverage of the implant by the periosteum and a wide wound area to minimize the risk of dehiscence during healing

Implant installationImplant installation There are three special concerns when installing the Zygoma

implant, due to its length and design.

1. Ensure that the implant is guided along the correct path of insertion through the sinus.

2. If the drilling unit stalls several turns before it reaches the implant's final seating position when set at 45 Ncm, it indicates that the bone site has not been prepared to its full depth with the twist drills. In such an event, back out the implant and prepare the bone site again to match the chosen implant length. Applying excessive torque can distort the implant head or fracture the implant mount or implant mount screw.

3. Rotate the implant to such a position that the angulated hexagonal top is directed towards an ideal occlusal plane. This can easily be verified by observing the position of the implant mount screw which corresponds to the position of the abutment screw.

SuturingSuturingTo minimize post-surgical bleeding and to ensure

complete closure of the wound, do the following:

Start with submucosal sutures, using a resorbable suture material.

Use non-resorbable vertical mattress sutures in the submucosa and mucosa.

This technique will minimize the risk of post-surgical dehiscence formation.

Place simple sutures between the mattress sutures. Do not suture them as deeply into the submucosa as the mattress sutures. These sutures assure a liquid-tight closure of the wound.

Healing PhaseHealing Phase

The maintenance of the zygoma implant patient is an ongoing process from the completion of stage I surgery through the entire healing phase.

As noted earlier, the existing or provisional upper denture can be modified for immediate use, giving the patient a continuous esthetic presentation.

Important to relieve the intaglio surface of the labial flange to prevent unnecessary apical pressure in the vestibular area.

Denture conditioning material is mixed and allowed to set for approximately 8 to 10 minutes, at which time it will have a viscous consistency.

The material is carefully applied to the borders of the modified denture and is then placed in the mouth and allowed to set while border molding.

With border molding movements intraorally, the conditioning material is physiologically formed to create a peripheral seal.

Any excess material is removed from the chamber so that no pressure is placed on the areas immediately over the implant sites.

At the time of stage II surgery the patient should present with well-healed maxillary mucosal surfaces and may occasionally exhibit a proliferative reaction into the denture base chamber space as seen here.

This excess tissue is not detrimental.

Protective SplintingProtective Splinting

Strength they provide when used with splinting and cross-arch stabilization.

Immediately following stage II surgery, or exposure of all implants with abutment connections, it is recommended that some protective measures be used to prevent independent stress transfer from the denture base to the implants individually.

ZYGOMA IMPLANTZYGOMA IMPLANT Radiographic analysis at

approximately 5 months of healing shows the implants in both arches appear to be osseointegrated.

Clinical validation of successful osseointegration is completed once the implants have been exposed and abutments have been connected.

Abutments are selected at stage II surgery with as low a profile as possible in order to minimize extension of the provisional splint into the denture base area.

In this case two 3 mm standard abutments have been selected for the right side, both of which terminate at the gingival tissue.

This is accomplished by making an impression immediately after the abutments are delivered and sending it to the dental laboratory for rapid turnaround.

A gold bar of approximately 2 mm in diameter is bent to contour so that it touches a set of gold cylinders attached to the abutment analogs on the cast.

With a microwelding device the bar and cylinders can be soldered together and within a short time period a passive protective splint can be fabricated. The bar splint is delivered, usually the next day, and the denture is hollow ground to allow complete seating without bar interference

At this time, a complete soft liner can be applied to the upper prosthesis to enhance comfort and retention

Final Prosthesis ConstructionFinal impressions can be made following

an adequate healing period, usually 3 to 4 weeks

The final impression is made using a custom tray, to control material thickness, and an open top technique, which allows the individual copings to be picked up rather than transferred into the impression material.

The master cast should be an absolute replica of the patient’s presentation intraorally.

Jaw relation records are obtained using implant-stabilized record bases and wax rims.

The try-in with teeth follows the trial set-up done in the laboratory, and patient approval of the esthetic presentation is confirmed.

The mounted casts should be an articulated representation of the patient’s jaw relationships.

The teeth are waxed to contour in positions dictated by the record base procedure and are sent to the clinic for try-in and patient approval.

Final approval for esthetic display, occlusion, and vertical dimension are all obtained at this clinical visit.

Silicone putty indexes are made of the approved wax-up and are used to provide a matrix for creation of a metal bar structure

The cast framework design is based on available space and tooth position as dictated by the wax set-up from the trial denture base. These dimensions are captured using a buccal index that keys to the master cast.

For greatest accuracy, the casting technique for these long-span restorations usually requires a runner bar and multiple sprue attachments to minimize distortion.

Following a second try-in appointment for evaluation of passive fit and esthetics, the prosthesis is processed with heat polymerizing resin

Delivery is accomplished using appropriate screws and screw torques to provide even and complete seating.

The bar structures are generally waxed and cast in precious metals but can also be milled from solid blocks of titanium with excellent passive fit properties.


In select situations, such as minimal interocclusal distance or high load forces, it may be beneficial to use a porcelain-fused-to-metal restoration.

The procedure for constructing these prostheses is essentially the same up to the point of the patient-approved wax-up. The metal substructure will be designed to provide architecture from the hybrid denture tooth design.

It may be especially advantageous to use the milled titanium technology for these restorations, since they do not tend to distort through the thermocycling phases of veneering to the same degree as the precious metal alloy cast substructures.

Post Insertion VisitPost Insertion VisitThe px should be seen one to two

weeks after delivery for a check upThe stability of the restoration is

checked A general evaluation of function,

phonetics, esthetics is madeThe stability of bridge retaining

screws are also tested and if necessary, the screws are re-tightened

SUMMARYSUMMARY The placement of implants and restoration of

the extremely atrophic maxilla is a challenge to both the surgeon and prosthodontist.

If conventional implants are to be used exclusively in this setting, extensive bone grafting is usually needed before implant insertion and usually includes sinus lifts and onlay grafts with large amounts of donor bone required.

The inconvenience, prolonged treatment,costs, potential complications, lower implant success rates, and donor site morbidity are important considerations.

This is further compounded by the patient’s inability to wear a prosthesis for extended periods of time—a factor that keeps many patients from pursuing treatment.

With the zygoma implant, bone grafts often may be avoided, treatment time is shortened, donor sites are unnecessary, and the patient may continue to wear a transitional prosthesis.

This results in greater patient acceptance while providing the patient with a well-tolerated, stable, and esthetic fixed or removable prosthesis at completion of treatment.

The advantages of considering the zygoma implant include the following:

1. Donor site morbidity is reduced or eliminated entirely.

2. Treatment time is markedly reduced or eliminated entirely.

3. Bone graft survival and consolidation are not considerations.

4. The total number of implants to support a prosthesis is reduced.

5. The treatment is more affordable and less invasive than alternative treatments.

The disadvantages of the zygoma implant include the following:

1. Technically demanding surgery— should only be performed by well- trained surgeons capable of dealing with any surgical situation or complications that might arise

2. Risk of injury to adjacent structures— that is, orbit, orbital contents, facial nerve, lacrimal apparatus, infraorbital nerve

3. Risk of postoperative sinusitis, although less than with sinus lift procedures

4. Fixture failure—although rare, more difficult to retreat

5. Surgical access difficult—deep sedation or general anesthetic required

As with all properly planned and executed implant prosthetic procedures, extensive coordination between the surgeon and the prosthodontist is necessary before initiating treatment. Ideally, the prosthodontist should be available at surgery.

Similarly, the surgeon should become familiar with the prosthetic needs and techniques involved with fixture positioning and restoration.

Finally, patient education, preparation, evaluation, and informed consent are major parts of the procedure and its ultimate success. ◦ Patient understanding, before treatment is initiated,

should include the need for meticulous hygiene and maintenance. The zygoma implant, when understood and appropriately used, provides a treatment alternative for many patients with atrophic edentulous maxillae.

References: Miloro, M et al, Peterson’s Principle of Oral and Maxillofacial

Surgery 2nd Ed., BC Decker Inc. 2004, pg. 235-259. http://www.institutodavo.com/webcms/usuario/

documentos/20110222134914_Inmediate_function.pdf http://jiads.net/Archives/2011/7.pdf http://coimplante.odo.br/Biblioteca/Implantes

%20Zigomaticos/Measurement%20of%20the%20Maxilla%20and%20Zygoma%20-%20Uchida%20et%20al.pdf

http://www.medicinaoral.com/pubmed/medoralv13_i6_p363.pdf

Zygoma Implant

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