Wallace,Maxillary Sinus Augmentation

8/3/2019 Wallace,Maxillary Sinus Augmentation

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Maxillary Sinus Augmentation: Evidence-Based Decision Making

With a Biological Surgical Approach

Stephen S Wallace, DDS;

Abstract:

Sinus elevation surgery has been used by the dental profession to increase

bone quantity in the posterior maxilla for the placement of root-form implants.

The original treatment protocol was developed using existing bone-healing

theories that relied on expert opinion. In 2003 and 2004, 2 evidence-based

literature reviews were published, expanding significantly on the previousreview of 1996. The new reviews were based on the best studies available

and were designed to present information that would help clinicians achieve

more favorable outcomes. This article discusses this information and answers

further questions relating to the sinus elevation procedure.

Learning Objectives:

After reading this article, the reader should be able to:

discuss the best evidence available on the sinus grafting technique.

explain 3 decisions that will improve the outcome of the sinus grafting

procedure.

describe the biological aspects of the surgical technique.

discuss sinus elevation as a standard in-office procedure with the use

of nonautogenous grafts.

Implant dentistry has dramatically changed the way we approach fully and

partially edentulous patients. A reconstructive approach introduced to

specifically address patients edentulous in the mandible has evolved to a

therapeutic modality that encompasses therapy in the edentulous maxilla, the

partially edentulous patient, and the patient missing 1 tooth.

Bone loss after tooth extraction or periodontal disease can complicate the

placement of root-form implants because of a lack of sufficient height or width of


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residual bone. This can be overcome with ridge augmentation procedures that

can restore the lost bone volume.

The posterior maxilla may present an additional obstruction to implant

placement caused by pneumatization (size increase) of the maxillary sinus.

Some patients have limited crestal bone height in the posterior maxilla even

when teeth are present, and it is not uncommon for the sinuses to pneumatize

further after the extraction of the posterior teeth. Pneumatization alone, without

additional loss of crestal bone caused by periodontal disease, may be sufficient

to complicate the placement of even short implants in the posterior maxilla

without previous sinus elevation surgery. Maxillary sinus floor elevation was

introduced to the profession by Boyne in 1980.1 In the 26 years since the

introduction of that technique, a host of surgical procedures have been

developed to correct bone deficiency created by sinus pneumatization. They

include variations of Boynes lateral window antrostomy, the osteotome sinus

floor elevation,2 crestal core elevation,3 and the localized management of the

sinus floor.4

Figures 1 and 2 give an example of the change in bone height that

can be achieved with the lateral window sinus elevation technique.

Recently published evidence-based literature reviews by Wallace and Froum,5

Del Fabbro and colleagues,6 and an as-yet unpublished review by Moy and

Aghaloo7

have reported remarkable levels of success (survival) for implants

placed in these grafted sites. Evidence-based reviews are structured,

unbiased compilations of the best scientific and clinical studies available. The

data from similar studies are then combined to form a large database to achieve

greater statistical power. The combined data are then subjected to meta-


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analysis so that the variables affecting the outcome of this procedure can be

isolated and their effects quantified.

Average implant survival rates reported were 91.8%, 91.5%, and 92%,

respectively. Although these survival rates appear to be less than acceptable,

the large databases provided by these reviews (5267, 6913, and 5128,

respectively) allow the reviewers to isolate selected variables and determine

their importance to successful clinical practice.

This decision-making process can lead to an increase in implant survival from

the average sinus lift survival rates reported in the previous paragraph to a

more clinically acceptable implant survival rate of 98.6%. This is an implant

survival rate comparable to what one can expect with implant placement in the

noncompromised anterior mandible.

The 3 goals of the sinus elevation procedure are the 1) creation of vital bone

in the posterior maxilla, 2) the osseointegration of the implants placed in

that bone, and 3) the survival of those implants under occlusal load. How

successful we are in this endeavor will be affected by the decisions we make

about the variables including graft material selection, membrane placement,

and implant surface selection that have been isolated in these reviews.

Evidence-Based Decision Making: Graft Materials

Autogenous bone was the first graft material to be widely used for sinus grafting.

Many early studies involved the harvesting of a block graft from the iliac crest

and then stabilizing this graft with implants placed through the remaining crestal

bone and into the graft. Autogenous bone grafts from the hip, knee, and various

intraoral sites also have been used in particulate form. Although autogenous

bone grafts provide a source of cells, growth factors, and bone morphogenic

proteins, the use of grafts of 100% autogenous bone has a number of

disadvantages. Harvesting of this bone may involve hospitalization (extraoral) or

require a second surgical site (intraoral), which increases the length of time of

the surgery, the surgical risk, and the morbidity of the procedure. Also, clinicians

have reported a more-than-average graft resorption rate when using 100% iliac

bone.8


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For these reasons, it has become practical to use bone replacement grafts

alone or in combination with autogenous bone as a sinus grafting material. The

bone replacement graft with the highest reported clinical use is the xenograft,followed by various forms ofallografts and alloplasts.5,6

Demineralized freeze-dried bone allografts also have been used as a sinus

graft material. Although they have been used successfully by some clinicians,

the results published after the Academy of Osseointegration Sinus Consensus

Conference showed both poor bone quality and a poor implant survival rate

(85%). Also, this demineralized graft is susceptible to slumping, or settling,

with a concomitant loss of graft height. It has a volumetric resorption rate

second only to that of autogenous bone.7

Mineralized bone allografts have macrostructures similar to autogenous bone.

The maintenance of this macrostructure is said by the manufacturer to depend

on the processing and sterilization techniques used to process this material.

Issues of safety for this material, as for demineralized freeze-dried bone

allografts and xenografts, involve factors concerning procurement of the

material and methods of processing and sterilization.

Xenografts have been very well documented as a sinus grafting material. They

have been used alone or as part of a composite graft combined with

autogenous bone, venous blood, or platelet-rich plasma. In the Wallace review,

the survival rate for implants placed in xenografts was similar to that of implants

placed in particulate autogenous bone grafts.5

The Del Fabbro review was even more specific in the documentation of the use

of xenografts.6Survival rates for implants placed in 100% xenograft, composite

grafts, and 100% autogenous bone grafts were 96%, 94.9%, and 87.7%,

respectively (Table 1).


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Studies by Hallman, Hising, and Valentini all have shown a higher implant

survival rate when using 100% Bio-Ossa as a bone replacement graft than

when either 100% autogenous bone or composite grafts of Bio-Oss andautogenous bone are used.

9-11

The Moy review shows similar findings for the use of xenografts and allografts.7

A large prospective study by Peleg and colleagues on simultaneous placement

of implants (2132) in sinus grafts that are mostly composites of intraorally

harvested bone with xenograft or allograft reported cumulative implant survival

at 8 to 9 years was 97.9%.12

The efficacy of mineralized bone replacement grafts such as xenografts is likely

because of a combination of factors:

1. osteoconductivity

2. slow resorbability

3. residual graft material does not interfere with osseointegration

The most important factor that can be attributed to xenografts is their

osteoconductivity.11,13,14

Osteoconductivity may be defined as the direct

apposition of vital bone on the xenograft surface (Figure 3). Newly formed vital

bone (red) is ultimately responsible for the osseointegration of the implant in the

grafted site.


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A second feature of the xenograft material is that it is slowly resorbable when

placed in the maxillary sinus. This quality prevents slumping (loss of graft

height) and adds approximately 25% to the overall mineral content of the

matured graft. An average taken from 8 published histological studies showed

25% vital bone formation, 25% residual xenograft, and 50% marrow in the

matured sinus graft. The resulting 50% total mineralized tissue (new bone plus


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residual graft) makes the future implant receptor site equivalent in density to

that of type 2 (dense) bone.

The third feature is the repeated histological finding that implants placed in

sinuses grafted with xenografts are never seen in direct contact with the graft

material.13,15

This is evidence that the residual graft material, while providing

support and density, does not interfere with osseointegration.

Issues of safety are of paramount concern to us as dentists when placing graft

material in the human body. A great amount of undue concern has been placed

on xenogenic material because of the outbreak

reported in the public press of bovine spongiform

encephalopathy in Europe. Regulations and

testing of xenografts are quite extensive. The raw

material is sourced from the long bones of US

cattle only. The material is processed by heat and

chemicals to ensure that it is sterile and prion-

free. For Bio-Oss the proof of deorganification is obtained through BioRad

assay, SDS-PAGE testing, and SDS-PAGE + Western blotting.16,17 To date,

there has never been a case of disease transmission attributed to particulatexenografts.

Evidence-Based Decision Making: Implant Surfaces

A second variable that affects implant survival in sinus grafts is the surface

texture of the implants that are placed in the graft. Both the Wallace (Table 2)

and Del Fabbro (Table 3) reviews show a dramatic difference in implant survival

when comparing rough to machined implants.5,6

The large difference observed in implant survival in both of the reviews is most

likely a result of differences in implant bone contact achieved by the rough and

smooth surfaces in the grafted sinuses. Non-sinus studies using special


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implants that have both surfaces on the same implant show a large difference in

implant bone contact between the surfaces. By having both surfaces on the

same implant, these studies rule out the variable of comparing implants thatwere placed in different sites. The study by Lazzara showed bone implant

contact for Osseotiteb and machined surfaces to be 79.7% and 46.5%,

respectively in good quality bone but only 51.7% and 8.1% respectively in poor

quality bone.18

Trisi, in a similar study, has shown that the bone-implant contact

with machined implants is usually less than you would expect given the bone

quality of the receptor site.19

On the contrary, the Osseotite surface always had

better than expected bone contact. Dziedzic has shown that the textured

Osseotite surface is better able to stabilize the blood clot on the surface,

allowing for bone formation directly on the surface (contact

osteogenesis).20

The inability of the machined surface to stabilize the blood

clot leads to retraction of the clot and bone formation away from the implant

surface (distance osteogenesis).

A recent retrospective analysis at the New York University Department of

Implant Dentistry has shown that machine-surface implants are much more

likely to fail than implants with textured surfaces when placed in sinus grafted

cases with reduced residual crestal bone height (SS Wallace and colleagues,unpublished data, 2005). This is yet another clinical deficiency resulting from

the poor bone implant contact that is established with a machined surface.

Evidence-Based Decision Making: Membranes

Membrane placement is the third major variable evaluated in the sinus reviews.

The Wallace review has shown that the use of a barrier membrane over the

lateral window has a positive effect on implant survival.5 The 3 controlled trials

listed in Table 414,21,22

all showed higher implant survival rates when a

membrane was used. Twenty additional studies showed implant survival with a

membrane to be 93.6% compared with 88.7% without a membrane.


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The advent of guided bone regeneration techniques in the early 1990s

improved our ability to repair compromised implant receptor sites. Sinus grafting

may be considered as a form of guided bone regeneration within a cavity.Guided bone regeneration uses membranes to isolate the area of regeneration,

maintain space, and exclude nonosteogenic connective tissue from the graft

site. When a membrane is placed over a grafted bone defect, completely

sealing the defect from the outside environment, the following characteristics

are observed in the regenerated tissue beneath the membrane:

1. corticalization of the graft surface

2. contiguity of the graft particles

3. increased vascularity of the graft

Histological studies of sinus grafts by Tarnow and colleagues and Froum and

colleagues both show these changes as well as a dramatic increase in vital

bone content when a membrane is used compared with cases where it is not

used (25% and 11.8%, respectively in the Tarnow study).14,21

As in guided bone regeneration, the first membranes used in sinus grafting

were nonresorbable GORE-TEX e-PTFEc membranes. To be effective, these

membranes had to be fixated by tacking them to the bone surface. Removal ofthe membrane required the flap reflection at the time of implant placement

surgery to be as extensive as it was for the lateral window surgery. If

bioabsorbable barrier membranes could be used over the lateral window and

achieve the same results, this latter surgery could be less extensive and

therefore less traumatic.

A recent study has compared the results using either absorbable (Bio-Gidea) or

nonabsorbable barrier membranes (GORE-TEX e-PTFE) over the lateral

window.23 The results showed both a similar vital bone formation (17.6% and

16.9%, respectively) and a similar implant survival rate (97.6% and 97.8%,

respectively) for the 2 types of membranes. Figure 4 shows a completely

regenerated lateral window area 8 months after sinus grafting with Bio-Oss and

a Bio-Gide membrane placed over the window.

Surgical Technique

A biologically based surgical approach that provides a large blood supply to the

graft appears to be beneficial to achieve the highest level of success in the


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sinus grafting procedure. The vascular supply to the grafted site comes from the

bony walls of the sinus. A proper elevation of the Schneiderian membrane must

include elevating the membrane from the medial wall of the sinus. This willdouble the blood supply to the graft, allowing for a more rapid formation of vital

bone and a reduction of the time necessary for graft maturation (Figures 5 and

6).

The lateral window technique begins with a full-thickness mucoperiosteal flap to

gain access to the lateral bony wall of the sinus. An antrostomy, or window, is

made in the lateral wall with either a diamond bur (using either a surgical or a

high-speed hand piece) orwith Piezosurgeryd. The bony window can then be

rotated horizontally along with sinus membrane elevation, or it can be

completely removed. The Schneiderian (sinus) membrane is reflected across

the sinus floor and then superiorly up the medial sinus wall. The elevated

membrane thus becomes the superior and distal walls of a compartment in the

lower third of the sinus that will receive the bone graft. Once the graft material is

placed, the lateral window should be covered with a biologic barrier membrane

before suturing the flap back into position. The graft is allowed to mature

(formation of new bone around the graft particles) before implant placement

(delayed approach), or the implants may be placed simultaneously with graftingif sufficient crestal bone is present to stabilize them. The implants are given

sufficient time to integrate in the grafted sinus and then restored with traditional

implant prosthetic components. The surgical procedure is demonstrated in

Figures 7 through 14.


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Piezosurgery is a technique new to the United States that has an 8-year history

of use in Europe. It is a safe, clean, and atraumatic technique for gaining

access to the sinus. Initial studies by the New York University sinus researchteam show a reduction in sinus membrane perforations from the typical average

of 30% to 7% in a study of over 100 consecutive cases24(Figures 15 through

18).

Conclusion

One result of the Wallace evidence-based review was the publication of the

following statement by the American Academy of Periodontology:

There is evidence to indicate that the lateral window technique for the sinus

bone augmentation procedure is successful at regenerating sufficient bone for

implant placement. The implant survival rate is greater than 90%, which is

similar to implants placed in native bone.5

The evidence-based reviews further identified some of the important variables

that affect the outcome of this procedure. These variables are as follows:

1. Particulate bone grafts result in a higher survival rate than block grafts.

2. Bone replacement grafts result in a higher implant survival rate than

autogenous bone or composite grafts.

3. Rough-surface implants result in a higher survival rate than machine-

surfaced implants.

4. Membrane placement over the lateral window results in a higher implant

survival rate than if a membrane is not used.

Additional studies were presented in this article, showing that the xenograft Bio-

Oss achieves its predictable success through a combination of its

osteoconductivity, its characteristic slow resorbability, and its lack of

interference with the process of osseointegration. Evidence was also presented

to show that, with regard to bone formation and implant survival, comparable

positive effects are achieved with the bioabsorbable Bio-Gide and the

nonabsorbable GORE-TEX e-PTFE barrier membranes.

A clinician can use an evidence-based decision-making process to dramatically

improve implant survival rates in the grafted maxillary sinus. In the Wallace

evidence-based review, the average implant survival for the lateral window


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procedure was 91.8%.5

By making the 2 decisions to use rough-surfaced

implants and particulate bone grafts, the implant survival rate became 94.5%.

By making a third decision to place a membrane over the lateral window, theimplant survival rate became 98.6%.

The ability to place implants in the compromised posterior maxilla with a very

high predictability will allow us to more predictably treat our patients with more

favorable treatment plans. Patient function and comfort will be improved if we

choose to place fixed restorations instead of removable dentures in our partially

and completely edentulous patients.

1. Boyne PJ, James RA. Grafting of the maxillary sinus floor with autogenous

marrow and bone. J Oral Surg. 1980; 38:613-616.

2. Summers RB. The osteotome technique: Part 3Less invasive methods of

elevating the sinus floor. Compend Contin Educ Dent. 1994; 15: 698-708.

3. Toffler M. Site development in the posterior maxilla using osteocompression

and apical alveolar displacement. Compend Contin Educ Dent. 2001; 22:775-

790.

4. Bruschi GB, Scipioni A, Calesini G, et al. Localized management of the sinus

floor with simultaneous implant placement: a clinical report. Int J Oral Maxillofac

Implants. 1998; 13:219-226.

5. Wallace SS, Froum SJ. Effect of maxillary sinus augmentation on the

survival of endosseous dental implants. A systematic review.Ann

Periodontol. 2003; 8: 328-343.

6. Del Fabbro M, Testori T, Francetti L, et al. Systematic review of survival rates

for implants placed in the grafted maxillary sinus. Int J Periodontics Restorative

Dent. 2004; 24:565-577.


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7. Moy PK, Aghaloo T. Academy of Osseointegration State of the Science on

Implant Dentistry Consensus Conference. Int J Oral Malliofac Implants. 2006; in

press.

8. Jensen OT, Shulman LB, Block MS, Iacono VJ. Report of the sinus

consensus of 1996. J Oral Maxillofac Implants. 1998; 13 Suppl: 11-45.

9. Hallman M, Sennerby L, Lundgren S. A clinical and histologic evaluation of

implant integration in the posterior maxilla after sinus floor augmentation with

autogenous bone, bovine hydroxyapatite, or a 20:80 mixture. Int J Oral

Maxillofac Implants. 2002; 17:635-643.

10. Hising P, Bolin A, Branting C. Reconstruction of severely resorbed alveolar

ridge crests with dental implants using a bovine mineral for augmentation. Int J

Oral Maxillofac Implants. 2001; 16:90-97.

11. Valentini P, Abensur D. Maxillary sinus floor elevation for implant placement

with demineralized freeze-dried bone and bovine bone (Bio-Oss): a clinical

study of 20 patients. Int J Periodontics Restorative Dent. 1997; 17:232-241.

12. Peleg M, Garg AK, Mazor Z. Predictability of simultaneous implant

placement in the severely atrophic posterior maxilla: A 9-year longitudinal

experience study of 2132 implants placed into 731 human sinus grafts. Int J

Oral Maxillofac Implants. 2006; 21: 94-102.

13. Valentini P, Abensur D, Densari D, et al. Histological evaluation of Bio-Oss

in a 2-stage sinus floor elevation and implantation procedure. A human case

report. Clin Oral Implants Res. 1998; 9: 59-64.

14. Froum SJ, Tarnow DP, Wallace SS, et al. Sinus floor elevation using

anorganic bovine bone matrix (OsteoGraf/N) with and without autogenous bone:

a clinical, histologic, radiographic, and histomorphometric analysisPart 2 of an

ongoing prospective study. Int J Periodontics Restorative Dent. 1998; 18:529-

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15. Scarano A, Pecora G, Piattelli M, et al. Osseointegration in a sinus

augmented with bovine porous bone mineral: histological results in an implant


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retrieved 4 years after case insertion. A case report. J Periodontol. 2004;

75:1161-1166.

16. Benke D, Olah A, Mhler H. Protein-chemical analysis of Bio-Oss bone

substitute and evidence on its carbonate content. Biomaterials. 2001; 22:1005-

1012.

17. Wenz B, Oesch B, Horst M. Analysis of the risk of transmitting bovine

spongiform encephalopathy through bone grafts derived from bovine bone.

Biomaterials. 2001; 22:1599-1606.

18. Lazzara RJ, Testori T, Trisi P, et al. A human histologic analysis of osseotiteand machined surfaces using implants with 2 opposing surfaces. Int J

Periodontics Restorative Dent. 1999; 19: 117-129.

19. Trisi P, Lazzara R, Rao W, et al. Bone-implant contact and bone quality:

Evaluation of expected and actual bone contact on machined and Osseotite

implants. Int J Periodontics Restorative Dent. 2003; 23: 535-546.

20. Dziedzic DM, Davies JE, et al. Proceedings of the 5th Biomaterials

conference. 1996.

21. Tarnow DP, Wallace SS, Froum SJ, et al. Histologic and clinical comparison

of bilateral sinus floor elevations with and without barrier membrane placement

in 12 patients: Part 3 of an ongoing prospective study. Int J Periodontics

Restorative Dent. 2000; 20: 117-125.

22. Tawil G, Mawla M. Sinus floor elevation using a bovine bone mineral (Bio-

Oss) with or without the concomitant use of a bilayered collagen barrier (Bio-

Gide): a clinical report of immediate and delayed implant placement. Int J Oral

Maxillofac Implants. 2001; 16:713-721.

23. Wallace SS, Froum SJ, Cho SC, et al. Sinus augmentation utilizing

anorganic bovine bone (Bio-Oss) with bioabsorbable and nonabsorbable

membranes placed over the lateral window: histomorphometric and clinical

analysis. Int J Periodontics Restorative Dent. 2005; 25: 551-559.


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24. Wallace SS, Mazor Z, Froum SJ, et al. Sinus membrane perferation using

piezosurgery: clinical results of over 100 cases. Int J Periodontics Restorative

Dent. 2006; in press.

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Wallace,Maxillary Sinus Augmentation