Zygoma Implants

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The use of zygomatic implants for the rehabilitation of atrophic

maxillas with 2 different techniques: Stella and Extrasinus

Ernesto Barquero Cordero, MSD,a Cesar A. Magalhes Benfatti, PhD,b

Marco A. Bianchini, PhD,c

Leonardo Vieira Bez, MSD,d

Kyle Stanley, DDS,e

andRicardo de Souza Magini, PhD,f Santa Catarina, BrazilUNIVERSITY FEDERAL OF SANTA CATARINA

The zygomatic implant anchorage is a surgical technique that provides a new perspective for patients withsevere maxillary atrophy, increasing predictability and reduced cost of treatment, besides being a tool for the hardshipsof the rehabilitation of such a challenging region. This article describes 2 clinical cases with zygomatic implants withdifferent techniques (Stella and Extrasinus) and both with immediate loading and accompanying clinical radiographicfollow-up procedures of 12 and 24 months, respectively. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:e49-e53)

The rehabilitation of patients with severely atrophiedmaxillas presents a major challenge owing to the com-

plexity of its implementation. The problem presents itself

because of the lack of height and width of the alveolar

ridge, this being a result of insufficient bone, extractions,

trauma, infection, or maxillary sinus pneumatization.1-3

Several surgical techniques have been developed to

successfully increase the volume of bone: iliac crest

graft, Le Fort I, guided bone regeneration, sinus lifting,

and combinations of these procedures.4-9 These treat-

ments also reduce patient comfort, increase morbidity,

require several surgeries, and require the use of remov-

able prostheses for a long period of time.10,11

Implants placed in grafted areas have various success

rates, with the literature suggesting a rate of 82% to 84%

with a clinical follow-up of 12 to 60 months.12

Aiming to simplify the treatment of these patients,

increasing the predictability of outcomes and decreasing

morbidity, treatment time, and avoiding bone grafts,

Brnemark and his team13 in 1988 implemented the an-choring technique known as zygomatic implants (ZI) in

some research centers.Initially this technique was designed to treat victims of

trauma, tumor resection, or congenital defects. These pa-tients present with a considerable loss of bone structure14

and few regions offering anchorage for the implants.These regions consisted of the body of the zygoma or the

frontal portion of the zygomatic bone15 presenting a greatalternative. With time, the technique has been refined,

allowing patients with severe bone resorption to be re-stored predictably to proper function and esthetics and

with a success rate similar to implants placed using theconventional technique.16

There are different techniques for fixation of zygomaticimplants. The technique developed by Brnemark17 calls

for a Le Fort I incision, allowing the displacement of alarge flap to facilitate exposure of the zygomatic bone, and

the realization of a window for the displacement of thesinus membrane. The technique of Stella and Warner18

differs from the original technique, as there is no need fora window opening on the wall of the maxillary sinus, only

1 channel orientation, and there is no concern for theintegrity of the sinus membrane. The third technique19 has

no need for a window opening or a channel in the wall ofthe maxillary sinus because of the externalization of the

zygomatic implants in relation to sinus. This article re-ports 2 clinical cases that were rehabilitated with different

fixation techniques, with a radiographic follow-up of 24and 48 months, respectively.

CASE DESCRIPTION

Case 1A 65-year-old female patient at the Center for Teaching

and Research in Dental Implants (CEPID) at the Federal

University of Santa Catarina (UFSC) presented to perform an

aPhD program in Implantology, University Federal of Santa Catarina,

Santa Catarina, Brazil.bAssociate Professor of Implantology, University Federal of Santa

Catarina, Santa Catarina, Brazil.cProfessor of the Phd and Masters Degree Program of Implantology,University Federal of Santa Catarina, Santa Catarina, Brazil.dResident of Implantology Program, University Federal of Santa

Catarina, Santa Catarina, Brazil.eResident of Implantology Program, University Federal of Santa

Catarina, Santa Catarina, Brazil.fChairman and Professor of PhD and Masters Degree Program of

Implantology, University Federal of Santa Catarina, Santa Catarina,

Brazil.

Received for publication Apr 28, 2011; accepted for publication May

15, 2011.

1079-2104/$ - see front matter

2011 Mosby, Inc. All rights reserved.

doi:10.1016/j.tripleo.2011.05.008

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implant reconstruction. Examining the panoramic radiograph

revealed bone loss around the upper and lower teeth, observed

clinically. With the impossibility of keeping these teeth, treat-ment options were introduced in the upper arch that would

use 4 implants, 2 anchored in the zygomatic bone and 2 in the

anterior region. The lower jaw had a treatment plan to place

4 implants. Both treatments had the possibility of immediate

loading.

The procedure was performed under general anesthesia

and was initiated by tooth extractions and smoothing maxil-

lary and mandibular alveolar ridges. Once the tissue was

reflected and the body of the zygoma was located, drilling

was initiated. With a round bur, a channel or slot was com-

pleted to define the orientation of the trajectory of the drills.

Then, the following sequence was used: 2.9-mm drill bit,

2.9-mm twist drill, 3.5-mm pilot drill, and 3.5-mm twist drill,always aiming the position of the platform of the implant to

lie as close as possible to the crest of the ridge. The next step

was the installation of the zygomatic implants, 4.1 diameter

52.0 mm in the posterior left ridge and 4.1 diameter 45.0 mm

in the right posterior border. Two implants measuring 4.1

13.0 mm were placed in the anterior. We used the posterior

multiunit abutments on 17 (right side) and 30 (left side),

both with a height of 4 mm, in order to have the emergence

profile located in the molar region. Because the torque was

greater than 40 Ncm for the implants in both arches, an imme-

diate loading protocol was initiated, tissue was sutured, and

acrylic resin (Duralay, Reliance) was used to secure the abut-

ment transfers in both arches and an impression for manufactur-

ing the prostheses was completed. After 48 hours, the prostheses

were installed, restoring function and esthetics for the patient.Panoramic radiographs were performed at 12 and 24 months for

the control treatment (Fig. 1, A-G).

Clinical case 2A 68-year-old male patient presented to the CEPID at

UFSC for rehabilitation of the upper jaw. On clinical exam-

ination there was a fixed prosthesis supported by implants in

the lower jaw and upper jaw with a thin ridge. It was sug-

gested that the patient have implants anchored in the zygo-

matic bone owing to the desire not to undergo a complex

reconstruction with extraoral donor sites. The procedure

started in the hospital with a LeFort type I incision, using the

ZI externalized technique. After the flap was reflected, thesequence of drilling included 2.9-mm pilot drill, 2.9-mm twist

drill, 3.5-mm pilot drill, and 3.5-mm twist drill. After the

placement of the implant platform directly over the ridge, the

installation of four zygomatic implants was completed, two

on the left side: 4.1 diameter 48 mm and 4.1 diameter 45

mm; on the right side 4.1 diameter 45 mm, 4.1 diameter

48 mm. We used a microunit-type abutment 17 with a height

of 4 mm, so as to have the emergence profile located in the

molar region. Because the torque was greater than 40 Ncm for

the implants in both arches, an immediate loading protocol

was initiated, tissue was sutured, and acrylic resin (Duralay,

Reliance) was used to secure the abutment transfers in both

Fig. 1. Patient 1. A, Intraoral photograph. B, Initial radiograph. C, A channel or slot was completed to define the orientation of

the trajectory of the drills. D, Zygomatic and conventional implants installed. E, Postoperative radiograph. F, Clinical photograph

showing the final prosthetic result. G, Radiographic follow-up at 24 months.

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arches and an impression for manufacturing the prosthesis

was completed. After 48 hours, the prosthesis was installed,

reestablishing the function and esthetics for the patient. Pan-

oramic radiographs were performed at 24 and 48 months for

the control treatment (Fig. 2, A-H).

DISCUSSIONAfter extractions, the process of bone remodeling in

the jaw suffers, causing inadequate dimensions for im-

plant placement. This atrophy is physiological and oc-curs in a chronic and irreversible fashion.6 The lack of

internal pressure along with posterior tooth extractionleads to bone resorption of the edentulous alveolar

ridge, making the retention of functional prosthesesdifficult and can lead patients to a disabled state in their

mouth with a decreased quality of life.20,21

Patients with major destruction of the premaxilla,maxillary sinus pneumatization, or defects owing totumor resection have limitations on treatment with oral

implants. Maxillary bone atrophy is classified by sev-eral authors19,20,21 as a major challenge, with a high

difficulty of rehabilitating a severely resorbed maxilla,indicating a major reconstruction with autogenous bone

grafts using extraoral donor sites,22 subsequent to theplacement of implants or anchoring techniques, without

bone reconstruction.The reconstruction techniques involve an increase in

the jawbone structure, aiming at the application of

conventional fixation in places where there is sufficient

alveolar height and thickness, providing the use of

implants in a much better position and, consequently,

better biomechanic distribution. The reconstructionscan be made on the alveolar ridge (onlay) or within

cavities, particularly the sinus (inlay).22 The grafts have

inevitably some element of risk, because they demand

good surgical technique, good quality of recipient bone,

soft tissue overlying the graft, great cooperation from

the patient, and general health of the patient that en-

courages healing.23 The literature shows a variability in

the survival percentage of the different techniques of

bone grafting being 80% to 95%,24-26 with a follow-up

time of 12 to 124 months. It also reports that the

success rate of implants in bone grafts is 74% to

87%.27-29

Initially, the ZI was designed to treat patients suffer-

ing from trauma or surgically resected tumors, where

there is great loss of jaw structures.11,23,30 Subse-

quently, the technique was applied to patients with

severe maxillary atrophy to simplify the treatment and

avoid a reconstruction.31 There are different techniques

for fixation of zygomatic implants, including the orig-

inal technique by Brnemark, which recommends

opening a window on the wall of the maxillary sinus as

well as maintaining the integrity of the sinus mem-

brane. The first case used a protocol originally pro-

Fig. 2. Patient 2. A, Intraoral photograph. B, Initial radiograph. C, Extrasinus zygomatic implant. D, Four zygomatic implants.

E, Clinical photograph. F, Postoperative radiograph. G, Final result (a, intraoral; b, extraoral). H, Radiographic follow-up at 48

months.

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posed by the Stella technique with the use of a channel

or slot through which the implant installation is guidedinto the sinus, eliminating the bony window and the

sinus lifting, having a larger implantbone interfacewith a vertical orientation and better emergence place-

ment of the implant closest to the crest of the alveolar

ridge. In the second case study, the extrasinus zygo-matic implant technique traces an imaginary line fromthe insertion point on the ridge to the point of attach-

ment to the body of the zygoma and the implant can becompletely or partially outside the sinus cavity. The

choice of technique is determined by the patients boneanatomy as well as technical skill of the clinician.

The zygomatic implant requires care in relation tothe biomechanical forces of curvature, whose forces

may impair the long-term stability of an implant-sup-ported restoration and, because of this, there must be

stiff prosthetic work, because flexing of the materials

used can cause deformation and deviation resulting inloss of fixation of the implants or loosening of the

junction between the prosthesis and fixation.32

The use of immediate loading with the 1 or 2 ZI on

each side is justified by some authors because theybelieve that the quality of the zygomatic bone, the rigid

stabilization and polygons created in the technique,coupled with the benefits provided to the patient (less

time, less cost, and possibility of social life) allows thisprocedure to be used.33,34 The use of prototypes seems

to be an interesting tool in the planning of this tech-nique, but high cost still hampers its use.35 An impor-

tant question is what could cause the presence of zy-gomatic implants inside the maxillary sinus. A study by

Nakai et al.36 in 2003 reported using computed tomog-raphy scans, performed 6 months after the installation

of 15 zygomatic implants, in 9 patients and showed nosigns of sinusitis. Petruson, in 2004,37 evaluated the

zygomatic implants in the maxillary sinus through asinuscopy in 14 patients, finding no infection or inflam-

mation in the mucosa around the implants.The success rates of implants in the zygomatic bone

vary from 95% to 97% with 12 to 124 months offollow-up observation,16,19,23,36-42 and a patient satis-

faction rate of 80% after 1 year of installation of theprosthesis.43

CONCLUSIONSClinically, the technique of zygomatic implants is an

excellent therapeutic modality for patients with atro-phic maxillas wishing to avoid a bone graft and there-

fore increasing predictability and reducing costs andmorbidity of treatment. The most important point in

this procedure is the clinical mastery of the techniquesfor this surgical approach, determining the success of

the treatment.

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Reprint requests:

Ernesto Barquero Cordero, PhD

Rua Duarte Schuttel 262, Ap 301

Centro, Florianpolis

Santa Catarina, Brasil 88015-640

[email protected]

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