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Purpose: To investigate the prevalence of anatomical and surgical findings and complications in

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tistmaxillary sinus floor elevation surgery, and to describe the clinical implications.

Patients and Methods: One hundred consecutive patients scheduled for maxillary sinus floor eleva-tion were included. The patients consisted of 36 men (36%) and 64 women (64%), with a mean age of50 years (range, 17 to 73 years). In 18 patients, a bilateral procedure was performed. Patients weretreated with a top hinge door in the lateral maxillary sinus wall, as described by Tatum (Dent Clin NorthAm 30:207, 1986). In bilateral cases, only the first site treated was evaluated.

Results: In most cases, an anatomical or surgical finding forced a deviation from Tatums standard proce-dure. A thin or thick lateral maxillary sinus wall was found in 78% and 4% of patients, respectively. In 6%, astrong convexity of the lateral sinus wall called for an alternative method of releasing the trapdoor. The samemethod was used in 4% of cases involving a narrow sinus. The sinus floor elevation procedure was hinderedby septa in 48%. In regard to complications, the most common complication, a perforation of the Schneide-rian membrane, occurred in 11% of patients. In 2%, visualization of the trapdoor preparation was compromisedbecause of hemorrhages. The initial incision design, ie, slightly palatal, was responsible for a local dehiscence in 3%.

Conclusion: To avoid unnecessary surgical complications, detailed knowledge and timely identificationof the anatomic structures inherent to the maxillary sinus are required. 2008 American Association of Oral and Maxillofacial SurgeonsJ Oral Maxillofac Surg 66:1426-1438, 2008

xillary sinus floor elevation with autogenous orthetic grafting material has proven to be a reliablethod that enables the insertion of endosseous im-nts in patients with a severely resorbed maxilla.

The classical sinus floor elevation consists of a tophinge door in the lateral maxillary sinus wall, asinvented by Tatum,1 but first described by Boyneand James 1980.2 The variety of anatomical modal-

Oral and Maxillofacial Surgeon, Department of Oral and Maxil-

cial Surgery, Free University Medical Center/Academic Center

Dentistry Amsterdam, Amsterdam, and St Antonius Hospital,

uwegein, The Netherlands.

Oral and Maxillofacial Surgeon, Department of Oral and Maxil-

cial Surgery, Free University Medical Center/Academic Center

Dentistry Amsterdam, Amsterdam, and St Antonius Hospital,

uwegein, The Netherlands.

Associate Professor, Department of Oral and Maxillofacial Sur-

y, Free University Medical Center/Academic Center for Den-

ry Amsterdam, Amsterdam, The Netherlands.

Professor, Department of Oral and Maxillofacial Surgery,

Free University Medical Center, Academic Center for Dentistry

Amterdam, Amsterdam, and Rijnland Hospital, Leiderdorp, The

Netherlands.

Address correspondence and reprints requests to Dr Zijderveld:

Department of Oral and Maxillofacial Surgery, St Antonius Hospital,

Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands; e-mail:

s.zijderveld@antonius.net

2008 American Association of Oral and Maxillofacial Surgeons

0278-2391/08/6607-0016$34.00/0

doi:10.1016/j.joms.2008.01.027

1426ral Maxillofac Surg1426-1438, 2008

Anatomical and SurComplications in

Maxillary SElevation P

Steven A. Zijder

Johan P.A. van den

Engelbert A.J.M. Schulte

Christiaan M. ten Bruggcal Findings and0 Consecutiveus Floorcedures

DDS, MD,*

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ZIJDERVELD ET AL 1427s in the shape of the inner aspect of the maxil-y sinus defines the surgical approach.3 Van denrgh et al described a number of anatomical con-erations.3

Several studies described separate anatomical find-s, such as blood supply to the lateral wall, sinusape, and sinus septa4-11 (Table 1). To the best of ourowledge of the literature, this is the first prospec-e study with regard to most of the anatomicaldings during 100 consecutive maxillary sinus floorvation procedures. To avoid unnecessary surgicalmplications, detailed knowledge and timely identi-ation of the anatomic structures inherent to thexillary sinus are required. The aim of the presentdy was to investigate the prevalence of differentatomical findings and complications in maxillaryus floor elevation procedures, and to describe thenical implications.

tients and Methods

For this prospective study, 100 consecutive pa-nts scheduled for maxillary sinus floor elevationre included. The patients consisted of 36 men%) and 64 women (64%), with a mean age of 50ars (range, 17 to 73 years). In 18 patients, a bilateralocedure was performed. All sinus floor elevationsre performed by the same surgeon.Only the first unilateral site was evaluated accord-to the anatomical findings and complications. All

tients were treated in the Department of Oral andxillofacial Surgery, Free University Medical Centermsterdam, The Netherlands), or at the Rijnlandspital (Leiderdorp, The Netherlands). Directly afterch sinus floor elevation procedure, a standardecklist was filled out, according to predefined cri-ia.Patients were treated with a sinus floor elevationhnique according to Tatum, ie, an osteotomy oflateral wall of the maxillary sinus.1 Patients treated

th a less invasive surgical approach for maxillaryus elevation (the transalveolar approach, as de-ibed by Summers12) were excluded from thisdy.In cases with a bilateral procedure, it was decidedevaluate only the first unilateral site. Patients werealuated according to anatomical findings, with sur-al relevance related to the maxillary sinus floorvation, and to complications. Anatomical findingsch as septa or perforations could only be countedce per patient. Surgical observations that called forforeseen and additional measurements, such asmbrane perforations or hemorrhages, were alsounted as complications, regardless of eventual heal-. In regard to complications, the follow-up periods restricted to an osseointegration time of 3nths after implant placement, and in this study, noservations were performed subsequent to implantlures.

sults

In most cases, an anatomical or surgical findingced a deviation from the standard procedure oftum.1 A thin or thick lateral maxillary sinus walls found in 78% and 4% of patients, respectively.In these cases, the initial trapdoor preparation dif-ed. The lateral wall was defined as thin if, afterection of the mucoperiosteum, the Schneiderianmbrane already shone dark grayish-bluish throughsinus wall. A maxillary sinus wall was considered

ck if it measured at least 2.3 mm, which was similarthe diameter of the stainless steel burr.In cases of strong convexity of the lateral maxillaryus wall, the inward and upward rotation of thectured door can easily lead to a mucosa tear at thenially placed trapdoor osteotomy. If the authorsserved this risk factor when releasing the trapdoor,lateral wall was scored as convex.

In 6% of patients, a strong convexity of the lateralus wall called for an alternative method of releasingtrapdoor. The same method was used in 4% of

tients with a narrow sinus. The prepared door wasnverted into a hatch, mobilized on four sides andrefully lifted upward. A wide sinus, observed in 7%patients, may lead to underfilling, so that the esti-ted bone height appears not to be the true boneight, leading to perforation of the implant into theus. The authors observed that the method of Tatum1

s hindered by septa in 48% of cases. Inversion of thene plate was complicated by these septa. The septare left intact, and the contour of the sinus was fol-ed by making a W-shaped trapdoor preparation or 2arated doors. In 5 cases, this alternative procedureulted in amembrane perforation at the location of theta. The perforations were then covered with aorbable barrier membrane, and because of thisper surgical measurement, the perforations had nogative effect on the eventual outcomes of the proce-res. In all 5 cases, the healing was not compromised.e prevalences of different anatomical findings areed in Table 2. We found no significant differencesth regard to gender or age.With regard to complications, the most commonmplication, perforation of the Schneiderian mem-ne, occurred in 11% of patients. As already men-ned, 5 perforations occurred in relation to septa, anddditional perforations were the result of extensionsially when releasing the Schneiderian membrane,cause of poor visibility. The direct connection be-een the sinus and oral mucosa was the cause in onee of a membrane perforation, occurring directly after

Table 1

Ulm et al,

Krennmai

Krennmai

Velasquez

Kim et al,

Cho et al,

Proussaef

Shlomi et

Ardekian

Solar et al

Elian et al

Uchida et

Abbrevi

Zijderveld14. ANATOMICAL STUDIES AND FINDINGS IN RELATION TO SINUS FLOOR AUGMENTATION PROCEDURES

Reference N Purpose Study Design Conclusions

199516 41 Prevalence and localization of septa Cadaver study Prevalence 31.7%Most septa (73.3%) in bicuspid region

r et al, 199718 65 Prevalence of septa Clinical examination Prevalence 27.7%200 Morphology of septa CT scan Prevalence 16.0%

Significantly greater dimension of septa in nonatrophicmaxillary regions

r et al, 19999 194 Prevalence and location of septa CT scan versuspanoramic x-ray

Prevalence significantly greater in atrophic maxillae thanin dentate regions

Panoramic x-ray less sensitive and specific than CT scan-Plata et al, 200222 312 Prevalence and morphology of

septaCT scan Prevalence 24%, prevalence significantly greater in

edentulous maxillas; most in middle region, at meanheights of 7.59, 5.89, and 3.54 mm in lateral, middle,and medial areas, respectively

200620 100 Prevalence and morphology ofsepta

CT scan Prevalence, 26.6%; 50.8% in the middle region; meanheights of 1.63, 2.44, and 5.46 mm in lateral, middle,and medial areas, respectively

200117 59 Influence of sinus anatomy onmembrane perforation

CT scan in correlationwith experiencedperforation rate

Perforation most frequently in narrow sinus

s et al, 200427 24 Effect of repair on perforated sinusmembrane

Human study, split-mouth design,histomorphometry

Perforated sites result in reduced bone formation inrelation to nonperforated sites (33.5% vs 14.1%), andreduced implant survival rates (69.5% vs 100%)

al, 200425 73 Incidence of membrane perforationand influence on clinicaloutcomes

Clinical andradiographic

Incidence of 28%, no statistically significant difference insurvival rate (90% vs 91% in control group) and ridgeheight pre- and postsurgery

et al, 200628 110 Significance of membraneperforation

Clinical Incidence of 32%, more frequently with low height ofresidual ridge, no difference in success rates

, 19995 18 Examination of vascularization ofthe lateral maxilla

Cadaver study Prevalence of intraosseous artery lateral maxilla, 100%;mean distance between intraosseous anastomosis inlateral maxilla and alveolar ridge, 19 mm

, 20054 50 Distribution of maxillary artery CT scan, intraosseousartery of lateralmaxilla

Prevalence of 52%, mean distance of 16 mm fromalveolar crest

al, 19987 38 Measurement of sinus volumes forbone grafting

CT scan and sinusfloor simulation

Mean volume of inferior portion of the sinus, 4.02 cm3

for 15-mm lifting, and 6.19 cm3 for 20-mm lifting

ation: CT, Computed tomography.

et al. Complications in Maxillary Sinus Floor Elevation Procedures. J Oral Maxillofac Surg 2008.

28COMPLIC

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ZIJDERVELD ET AL 1429ection of the mucoperiosteum. Fortunately, this per-ation remained relatively small. In 1 perforation, noatomical explanation could be given. The perforationsre all covered with a barrier membrane, and theentual healing was uneventful.In 2% of patients, visualization of the trapdoor prep-tion was compromised because of hemorrhages. Inr study group, only 1 patient developed postoper-ve maxillary sinusitis. This patient had no preoper-ve risk factors, such as sinus pathology in the past,r a perioperative perforation of the Schneiderianmbrane.The initial incision design, ie, slightly palatal, wasponsible for local dehiscence in 3% of patients. In 2tients with local wound dehiscence, graft infections observed along with a purulent discharge, and wasated by antibiotic therapy and local debridement. Thehiscence healed by secondary granulation.At the time of implantation in 1 patient, the sinusvity was reached after drilling to a depth of 8 mm,icating a partial loss of the graft. This patientowed no signs of infection, and in particular, noxillary sinusitis in the time of healing after eleva-n. As an alternative explanation for this finding, thehneiderian membrane was probably not elevated asas the medial wall, resulting in underfilling withft material of the created space.

able 2. ANATOMIC FINDINGS IN 100ONSECUTIVE MAXILLARY SINUS FLOORLEVATION PROCEDURES

in lateral sinus wall 78%ick lateral sinus wall 4%nvex lateral sinus wall 6%nnection of Schneiderian membrane andral mucosa 2%rrow sinus 4%de sinus 7%us septa 48%ngitudinal sinus septum 2%ot-shape configurations 4%

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

able 3. COMPLICATIONS IN 100 CONSECUTIVEAXILLARY SINUS FLOOR ELEVATION PROCEDURES

rforation of Schneiderian membrane 11%rioperative hemorrhages 2%stoperative hemorrhages 0%stoperative maxillary sinusitis 1%cal wound dehiscences 3%aft infections 2%ss of graft 1%ss of implants 4%

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.In 4 different patients, 4 implants were lost duringosseointegration period of 3 months. In a total of

3 implants placed, this was equivalent to 1.6%. Weuld not find any relationship to the remaining crest

URE 1. Pneumatization of maxillary sinus after tooth loss,bably caused by reinforcement of osteoclastic activity of theneiderian membrane.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

URE 2. A, In cases of a thin maxillary sinus wall, after reflec-of the mucoperiosteum, the Schneiderian membrane already

nes a dark grayish-bluish through the lateral sinus wall. B, Theral door preparation is made directly with a round diamondr, without use of a stainless-steel burr.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

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1430 COMPLICATIONS IN MAXILLARY SINUS FLOOR ELEVATION PROCEDURESthe native maxilla. In none of these patients did anyer complication, as mentioned in this study, occur.mplications are listed in Table 3.

scussion

ANATOMICAL FINDINGS

Thin or Thick Lateral Maxillary Sinus WallAfter loss of the maxillary teeth and reduction of thesticatory forces acting on the maxilla, the sinus walldually becomes thinner as a result of the increasede (or volume) by pneumatization of the maxillaryus.13 The duration of edentulism is decisive for thetent of alveolar-ridge resorption and antral pneumati-

URE 3. Schematic drawing of the thinning out of a thick lateralll for the purpose of a good visualization of the inner aspect ofbony sinus.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

FIGURE 4. A profound convexity of the maxillary sinus w

derveld et al. Complications in Maxillary Sinus Floor Elevationion of the alveolar process. Increased antral pneu-tization starting after tooth loss seems to result espe-lly from the basal bone loss caused by anforcement of osteoclastic activity of the Schneide-n membrane (Fig 1).15 In extreme cases, only a paper-n lamella of bone separates the maxillary sinus fromoral cavity after long-term edentulism.16

In cases of a very thin maxillary sinus wall, carefulection of the mucoperiosteum is recommended,ile the Schneiderian membrane already shines darkyish-bluish through the sinus wall (Fig 2A). Reflec-n of the mucoperiosteum with sharp instrumentsn already cause a perforation of the sinus wall andSchneiderian membrane. In the present study,

er reflection of the mucoperiosteum, this transpar-t, dark aspect was observed in 78% of cases. Be-use of the risk of perforation of the Schneiderianmbrane during lateral door preparation in theseses, it is advised not to begin the lateral door prep-tion with a round stainless-steel burr, but to use and diamond burr directly, and thus reduce the riska membrane perforation (Fig 2B).If the lateral wall consists of thick bone, the wholeeral wall should be thinned out (Fig 3). When theinless-steel burr, with a diameter of 2.3 mm, totallyed the lateral osteotomy (Fig 3), this alternativeocedure was followed. Otherwise, it would be ex-mely difficult to mobilize the Schneiderian mem-ne from the inner aspect of the bony sinus, be-use instruments cannot reach this tissue due to aep cleft-like approach.3

Convex Lateral Sinus WallIn 6% of the patient population in this study, thenvexity of the lateral maxillary sinus wall called for

etimes required an alternative trapdoor preparation.

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ZIJDERVELD ET AL 1431alternative trapdoor luxation (Fig 4). In normalses, the procedure consists of the preparation of ahinge door in the lateral maxillary sinus wall. In

ses of a convex lateral sinus wall, the inward andward rotation of the fractured door can easily leada mucosa tear at the cranially placed trapdoor

URE 5. A, Patient with a convexity of the lateral sinus wall. B,prepared door was mobilized on 4 sides and lifted upward.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

URE 6. Perforation immediately after reflection of the mucope-teum, because of direct contact of the sinus mucosa with thel mucosa.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.teotomy. Therefore, in cases of profound convexitythe maxillary sinus wall, an alternative approach isvisable, in which the prepared door is converted tohatch, mobilized on 4 sides and carefully liftedward to a horizontal position in the maxillary sinusgs 5A,B). Alternatively, the trapdoor preparationn be placed medial to the convexity of the lateralus wall, tunneling farther in a distal direction, al-ugh this creates a higher risk of perforating thehneiderian membrane.

Connection Between the SchneiderianMembrane and Oral MucosaWhen the alveolar bone is totally absent in someces (because of resorption or traumatic bone losser tooth extraction, eg, sinus perforation), the sinuscosa may be in immediate contact with the oralcosa. This is a very difficult condition, in which thehneiderian membrane cannot usually be kept intactg 6). It may lead to large perforations at very diffi-lt sites, making any further preparation impossi-.3

Previous sinus surgery (eg, a Caldwell-Luc proce-re) sometimes constitutes a contraindication forxillary sinus floor elevation, because anatomicalconfigurations do not allow for the preparation ofact, healthy mucosal tissue (Fig 7). In cases ofevious sinus operations, a preoperative computedography (CT) scan can be helpful in demonstrat-this condition.

The Narrow and Wide SinusUntil the eruption of permanent teeth, the sinusvities are insignificant in size. The development ofmaxillary sinus is a dynamic, active procedure

en 2 conditions apply: a slight, positive intrasinusessure, and good physiology of the mucosal sinus

URE 7. Absence of the lateral maxillary sinus wall, because ofvious sinus surgery (a Caldwell-Luc procedure). This is a contra-ication for sinus floor elevation. R, right; P, posterior.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

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1432 COMPLICATIONS IN MAXILLARY SINUS FLOOR ELEVATION PROCEDURESmbrane, which should be supple and easy to ex-nd, as well as capable of bone resorption and thin-g the sinus wall. This is in line with the presenceosteoclasts found in the maxillary sinus, as theteoclastic activity is jointly responsible for the re-rption and thinning of the sinus wall.15

There is a wide range in sizes and shapes of max-ry sinuses. In a study by Uchida et al,7 maxillaryus volumes were measured using CT images of 38uses and a 3-dimensional reconstruction system.e average total maxillary sinus volume was 13.6 cc. The minimum maxillary sinus volume was 3.5

, and the maximum was 31.8 cc.7

The size of the sinus, and especially the angulationtween the medial and lateral walls of the maxillaryus, seemed to exert a large influence on the inci-nce of membrane perforation during maxillary si-s floor elevation. The sharper angles observed atinner walls of the sinus at the sites of the second

per bicuspid presents a higher risk of perforation.e angulation will influence the feasibility of theus floor during elevation. Group 1 of Cho et al17

nsisted of specimens with an angle of 30 or less,up 2 consisted of specimens with angles between and 60, and group 3 consisted of specimens withgles of 61 or greater. The different groups demon-ated significant correlation with the observed per-ations. The perforation rates were 37.5% (group 1),.6% (group 2), and 0% (group 3).17 The sites of thet upper molars are the least difficult areas.8,17 Inpresent study, 4 patients had a narrow maxillary

us that required an alternative surgical approach.The most reliable method in terms of being preop-tively informed about the size and shape of thexillary sinus is a CT scan. With a preoperative CTn, a narrow maxillary sinus can be anticipated.e way to circumvent the problem of a narrow sinusby performing an antrostomy in the lateral walltead of a door preparation. In this situation, how-er, the sturdy bone support and a new floor of theus will be absent, and the one bone-inductive ele-nt for the bone graft will fail. Alternatively, theepared door can be converted into a hatch, mobi-ed on all 4 sides and carefully lifted (pedunculatedly to the sinus mucosa) upward to a higher positionthe maxillary sinus, where the lateral sinus dimen-ns are larger (Figs 8A,B).3 In such cases, it is ad-ed to make an all-around preparation, to minimizerisk of perforating the Schneiderian membrane. In4 cases in the present study, this alternative surgi-l method was chosen.In cases of a wide maxillary sinus, it is recom-nded to make a large door preparation, and lift theor to a high position cranially. However, without aeoperative CT scan, the surgeon is mostly unin-med about this possibility. Especially in a wideus, there is a risk of underfilling the recipient siteth grafting material if elevation of the membranes not been continued as far as the medial wall. Thisderfilling might lead to later complications, if theimated bone height appears not to be the truene height during implant surgery, leading to perfo-ion of the implant into the sinus (Fig 9).

Maxillary Sinus SeptaThe presence of septa increases the risk of sinusmbrane perforation during sinus floor elevationocedures. This anatomic variation was first de-ibed by Underwood in 1910,11 and therefore ismetimes referred to as Underwoods septa. In anatomical study, Underwood11 found 30 septa in 90

URE 8. Axial computed tomography scan (A) and schematicwing (B) of the narrow maxillary sinus. The prepared door canconverted into a hatch, mobilized on all 4 sides, and carefullyd (pedunculated only to the sinus mucosa) to a higher positionthe maxillary sinus. Arrows indicate the direction in which thedoor should be displaced.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

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ZIJDERVELD ET AL 1433xillary sinuses, showing a prevalence of 33%. Theidence of antral septa varies between 16% and%.9 The prevalence of septa was significantlyater in atrophic edentulous regions than in dentateions. Krennmair et al9,18 hypothesized that if teethgradually lost, atrophy begins at different times inferent regions. They classified septa into primaryhich arise from the development of the maxilla)d secondary (which arise from irregular pneumati-ion of the maxillary sinus floor after tooth loss).cause maxillary molars are often lost earlier thanpremolars, the different phases of maxillary sinuseumatization result in the formation of antral septa.nce Krennmair et al9,18 stated that 70% of antralta were found in the anterior region. Stover criti-ed these conclusions, stating a greater prevalencesepta in the posterior segments results from rem-nt interradicular bone between adjacent maxillarylars.19

The prevalence of primary septa was found to benificantly higher.9,20-22

The average height of medial insertions was greatern that of the lateral insertions. In other words,tal height increased from lateral to medial inser-ns. This can complicate the inversion of the bonete or lateral door.Panoramic radiography has less sensitivity andecificity than CT scanning for the detection of sinusta (Fig 10). Krennmair et al9 reported a false-sitive or negative diagnosis regarding the presenceantral septa in 21.3% of cases.In instances where septa are encountered on theus floor, Boyne and James2 recommended cuttingm with a narrow chisel and removing them with amostat, so that the bone graft can be placed overentire antral floor. Tidwell et al23 subdivided the

URE 9. In a wide sinus, seen on this axial computed tomogra-scan, there is a risk of underfilling if the elevation of the

mbrane has not been continued as far as the medial maxillaryus wall.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.ny wall into an anterior and a posterior part of thege door, and inverted both trapdoors.The present authors suggest following the contourthe sinus floor by making a W-shaped preparationsmaller septa, or 2 separate doors (Figs 11A-C).3

other option would involve an antrostomy ap-oach.24

Longitudinal SeptumElevation of the Schneiderian membrane is a time-nsuming procedure. In most cases, upon reachingfloor of the maxillary sinus, visibility improves,

celerating the procedure.However, in 2 cases, a horizontal and longitudinalwas encountered, in mesiodistal or sagittal direc-

n instead of the usual transversal septa, halfwaytween the sinus floor and medial wall. Because ofs unexpected rim, there was a risk of perforatingmembrane while shooting out with an elevation

trument. In contrast to a root-shape configuration,s rim is located along the full length of the sinusor (Fig 12).

Root-Shape ConfigurationsRoot-shape configurations, found in 4 patients ofstudy group, can be expected when teeth have

en extracted recently (Fig 13). In 2 of 4 cases, thearation of the Schneiderian membrane caused arforation at this particular location. If possible, si-s floor elevation should be delayed for at least 6nths after extraction of the teeth when root-tippressions in the maxillary sinus are clearly visiblea panoramic radiograph.

URE 10. The coronal computed tomography scan has a highsitivity and specificity for the detection and localization of sinusta.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

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1434 COMPLICATIONS IN MAXILLARY SINUS FLOOR ELEVATION PROCEDURESSURGICAL FINDINGS

Maxillary Sinus-Membrane PerforationSinus-membrane perforation is the most prevalentmplication of sinus floor elevation procedures (10%60%).25-28 Anatomic as well as technical factorsve been implicated in membrane perforation. Theegrity of the sinus membrane is essential in main-ning the healthy, normal function of the maxillaryus. The mucociliary apparatus protects the sinusainst infection by removing organisms trapped incus through the ostium. The membrane also actsa biologic barrier, and an increased chance ofection results if the biologic barrier (the mem-ne) perforates because a greater number of bacte-can invade the graft. Possible causes of perforationlude tearing of the membrane during window os-tomy or with an infracture of the bony window,vation of the membrane, the presence of septa,d overfilling with graft material.26 Documented risktors include irregularities of the sinus floor, rootmations, previous sinus surgery (scar tissue), andlower height of the residual alveolar crest.3,28

dekian et al28 reported that in residual ridges of 3, a perforation of the sinus membrane occurred

85% of cases, whereas in residual ridges of 6 mm,

URE 11. A, B, The suspected sinus septa on the antral floor is lefneiderian membrane is at risk of being torn, particularly at the cran

derveld et al. Complications in Maxillary Sinus Floor Elevationerforation was observed in 25% of cases. In mostdies, no statistical difference was observed insuccess rates of implants placed with sinus

ne grafting in patients whose Schneiderian mem-ane was perforated versus those patients inom the membrane remained intact. However, atomorphometric study according to a split-mouthsign, and with regard to sinus perforation duringrgery, suggested that repairing the perforated sitethe sinus membrane with a resorbable collagenmbrane may result in reduced bone formation andeduced implant survival rate.25 When the perfora-n is small (2 mm) and located in an area whereelevated membrane is folded together, it will healitself. However, even with a small perforation or ary thin Schneiderian membrane, the present au-rs prefer to use a resorbable collagen membrane tover and support the weak spot. Larger perforationsalmost always managed by the use of a barriermbrane. In the present study, a freeze-dried humanellar bone sheet (Lambone; Pacific Coast Tissue

nk, Los Angeles, CA) was applied after it wasaped and cut for proper fit. The large size of a sheethosen to provide a customized fit within the bonyus walls. The corners are rounded off, and the

and visualized by making 2 trapdoors. C, When elevated, thee of the septum. A membrane is placed to cover the perforation.

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ZIJDERVELD ET AL 1435mbrane is rehydrated before placement in thexillary sinus (Figs 14A-C). Other treatment optionslude the use of an autogenous block graft insteada cancellous graft, suturing, or abandonment of thergical procedure.With regard to the prevention of a perforation, theesent authors make some additional small holes insuction device, to diminish the suction power.

rthermore, the prevention of direct contact of thection device with the Schneiderian membrane canachieved by placing an elevation instrument be-een them.

HemorrhagesKnowledge of the blood supply to the maxillaryus is of importance in sinus floor elevation proce-res, in terms of both vascularization of the sinusft and the location of that blood supply relative toposition of the required lateral osteotomy. The

rgical severance of one of the vessels may not be a-threatening event, but may complicate the proce-re, because of the more difficult visualization of thehneiderian membrane. Although the maxilla is verynsely vascularized in young and dentate popula-ns, the blood supply to the bone is permanentlyuced with age and progressing atrophy, and thember of vessels and their diameters decrease, whiletuosity increases.4 Three arteries supply the max-ry sinus: the posterior superior alveolar, infraor-al, and posterior lateral nasal arteries, all of which

URE 12. Schematic drawing of a longitudinal or sagittal sep-, instead of the usual transversal septum, of the antral floor.ause of this unexpected rim, there is a risk of perforating thembrane while shooting out with an elevation instrument.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.ultimate branches of the maxillary artery. Thesterior superior alveolar artery supplies the liningthe antrum, posterior teeth, and superficialnches to supply the maxillary gingivae and muco-riosteum. The dental branch of this artery coursesraosseously, halfway up the lateral sinus wall, andms a horizontal anastomosis with the infraorbitalery. The infraorbital artery runs through the infra-ital canal and, before emerging from the infra-ital foramen, it gives off 1 or 2 branches thaturse caudally along the anterior antral wall.29 Anraosseous anastomosis was found in all specimensan anatomic study of cadavers, and was visualized53% of the CT scans in a radiographic study.4,5 In2 studies, the mean distance of the intraosseous

astomosis to the alveolar crest was 19 mm and 16, respectively. If the goal is to place implants 12in length, the superior osteotomy cut will be

de approximately 14 mm from the alveolar crest.cording to CT scan data, 80% of the arteries areated more than 15 mm from the crest, and are atrisk regarding a potential surgical complication.4

t in cases where the alveolar ridge has been se-rely resorbed, the vessel will be closer to the crestn the reported average.In the present study, a hemorrhage during prepa-ion of the trapdoor was encountered in 2 patientsg 15). In both patients, it reduced the visualizationd hindered the surgical procedure, but had no nega-e influence on the treatment outcome. Bleeding canally be controlled by pressure with a mist gauze pad.

URE 13. Schematic drawing of dental root-shape configura-that makes preparation of the membrane difficult.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.

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1436 COMPLICATIONS IN MAXILLARY SINUS FLOOR ELEVATION PROCEDURESctrocautery should be avoided, because there is a riskperforating the Schneiderian membrane.Solar et al5 reported on an extraosseous anastomo-of the same arteries mentioned in 44% of the cases.is located at a mean distance of 23 mm from theeolar ridge. The anastomosis is in close contactth the bone. Vertical incisions should thereforetend cranially as little as possible, and the perios-m should be prepared with the utmost care, tonimize vascular trauma.In addition to anastomosis in the lateral wall of thexillary sinus, a third artery can be a potential risksevering an intraosseously located artery during aorous curettage for sinus elevation in the posteriordial wall of the sinus. The posterior lateral nasalery can be found close to, or within, the medialll of the sinus, and because of the proximity of thehenopalatine artery, it may produce a problematicw of blood if severed.6

Another form of perioperative or postoperativeeding that can occur is an epistaxis, indicating ambrane perforation.

Postoperative Maxillary SinusitisThe rather low complication rate of 1% for postop-tive maxillary sinusitis is somewhat surprising. A

URE 14. A, Patient with a perforation of the Schneiderian membng shaped and cut for proper fit. C, The recipient side was filled w

derveld et al. Complications in Maxillary Sinus Floor Elevationnsient or persisting effect on the ciliated antralcosa would be expected as a result of maxillaryus floor elevation raising the Schneiderian mem-ne. When the maxillary sinus is filled with blood, alay of maxillary sinus clearance is thought to occur,cause it is generally assumed that a reduction of thetency of the osteomeatal unit creates a potential

, A freeze-dried human lamellar bone sheet was applied afterrticulated autogenous bone graft from the retromolar trigonum.

ures. J Oral Maxillofac Surg 2008.

URE 15. Hemorrhages during preparation of the trapdooruced the visualization and hindered the surgical procedure.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.tramusinbradebepa

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ZIJDERVELD ET AL 1437k for the development of maxillary sinusitis. How-er, the results of a human study by Timmenga et al30

regard to the effects of maxillary sinus floor elevationmaxillary sinus physiology suggest that the maxillaryus mucosa is capable of adapting adequately to theanges induced by elevation procedures, especiallycases of noncompromised sinus clearance.

Local Wound DehiscencesIn 3 cases, a local wound dehiscence occurred infirst 2 weeks postoperatively. This was probably

cause, in the first treated patients, the incision ontop of the crest was made slightly palatal (Figs

A,B). The main course of the supplying arteries ism posterior to anterior, the main vessels run par-el to the alveolar ridge in the vestibulum, and thestal area of the edentulous alveolar ridge is cov-d by an avascular zone with no anastomosesssing the alveolar ridge. This argues in favor ofdline incisions on the alveolar ridge and avoidanceincisions crossing the alveolar ridge, hence elimi-ting the risk of cutting anastomoses or cutting outascular areas of the mucosa.31

The relatively low rate of complications in thistient group was probably attributable to the perfor-

URE 16. A, The horizontal incision on top of the crest wasde slightly palatal. B, Postoperatively, a local wound dehis-ce occurred.

derveld et al. Complications in Maxillary Sinus Floor Elevationcedures. J Oral Maxillofac Surg 2008.nce of all procedures by 1 skilled surgeon. Inxillary sinus floor elevation procedures, it is essen-l to have good knowledge of the different anatom-l and surgical findings, to minimize perioperatived postoperative complications. The results of thisdy contribute to a better understanding of thiseimplant procedure.

ferencesTatum OH: Maxillary and sinus implant reconstructions. DentClin North Am 30:207, 1986Boyne P, James RA: Grafting of the maxillary sinus withautogenous marrow and bone. J Oral Maxillofac Surg 38:113,1980van den Bergh JPA, Bruggenkate CB, Disch FJM, et al: Anatom-ical aspects of sinus floor elevation. Clin Oral Implant Res11:256, 2000Elian E, Wallace S, Cho S, et al: Distribution of the maxillaryartery as it relates to sinus floor augmentation. Int J OralMaxillofac Implants 20:784, 2005Solar P, Geyerhofer U, Traxler H, et al: Blood supply to themaxillary sinus relevant to sinus floor elevation procedures.Clin Oral Implant Res 10:34, 1999Flanagan D: Arterial supply of the maxillary sinus and potentialfor bleeding complication during lateral approach sinus eleva-tion. Implant Dent 14:336, 2005Uchida Y, Goto M, Katsuki T, et al: Measurement of maxillarysinus volume using computerized tomographic images. IntJ Oral Maxillofac Implants 13:811, 1998Velloso GR, Vidigal GM, Freitas MM de, et al: Tridimensionalanalysis of maxillary sinus anatomy related to sinus lift pro-cedure. Implant Dent 15:192, 2006Krennmair G, Ulm C, Lugmayr H: Maxillary sinus septa: Inci-dence, morphology and clinical implications. J Craniomaxillo-fac Surg 25:261, 1997Ulm CW, Solar P, Krennmair G, et al: Incidence and surgicalmanagement of septa in sinus-lift procedures. Int J Oral Maxil-lofac Implants 10:462, 1995Underwood AS: An inquiry into the anatomy and pathology ofthe maxillary sinus. J Anat Physiol 5:354, 1910Summers RB: The osteotome technique. Less invasive methodsof elevating the sinus floor. Compend Contin Educ Dent 15:698, 1994Jensen OT: The sinus bone graft. Carol Stream, IL, QuintessencePublishing, 1999Tallgren A: The continuing reduction of the residual alveolarridges in complete denture wearers: A mixed longitudinalstudy covering 25 years. J Prosthet Dent 27:120, 1972Chanavaz M: Maxillary sinus: Anatomy, physiology, surgery andbone grafting related to implantology. J Oral Implantol 16:199,1990Ulm CW, Solar P, Gsellmann B, et al: The edentulous maxillaryalveolar process in the region of the maxillary sinusA studyof physical dimensions. Int J Oral Maxillofac Surg 24:279, 1995Cho SC, Wallace SS, Froum SJ: Influence of anatomy on Schnei-derian membrane perforations during sinus floor elevation sur-gery: Three dimensional analysis. Pract Periodont Aesthet Dent13:160, 2001Krennmair G, Ulm CW, Lugmayr H, et al: The incidence,location and height of maxillary sinus septa in the edentulousand dentate maxilla. J Oral Maxillofac Surg 57:667, 1999Stover JD: Discussion: The incidence, location and height ofmaxillary septa in the edentulous and dentate maxilla. J OralMaxillofac Surg 57:671, 1999Kim M, Jung U, Kim C, et al: Maxillary sinus septa: Prevalence,height, location and morphology. A reformatted computed to-mography scan analysis. J Periodontol 77:903, 2006Lungmayr H, Krennmair G, Holzer H: Morphologie und Inzidenzvon Kieferhhlensepten. Fortschr Rontgenstr 165:452, 1996

22. Velasquez-Plata D, Hovey LR, Peach CC, et al: Maxillary sinussepta: A three dimensional computerized tomographic scananalysis. Int J Oral Maxillofac Surg 17:854, 2002

23. Tidwell JK, Blijdorp PA, Stoelinga PJ, et al: Composite graft-ing of the maxillary sinus for placement of endosteal im-plants. Int J Oral Maxillofac Surg 21:204, 1992

24. Bruggenkate CB, van den Bergh JPA: Maxillary sinus floorelevation a valuable pre-prosthetic procedure. Periodontology17:176, 2000

25. Shlomi B, Horowiz I, Kahn A, et al: The effect of sinus membraneperforation and repair with Lambone sheet on the outcome ofmaxillary sinus floor augmentation: A radiographic assessment. IntJ Oral Maxillofac Implants 19:559, 2004

26. Pikos M: Maxillary sinus membrane repair: Report of a tech-nique for large perforations. Implant Dent 8:29, 1999

27. Proussaefs P, Lozada J, Kim J, et al: Repair of the perforatedsinus membrane with a resorbable collagen membrane: A hu-man study. Int J Oral Maxillofac Impl 19:413, 2004

28. Ardekian L, Oved-Peleg E, Mactei E, et al: The clinical sig-nificance of sinus membrane perforation during augmenta-tion of the maxillary sinus. J Oral Maxillofac Surg 64:277,2006

29. Traxler H, Windisch A, Geyerhofer U, et al: Arterial bloodsupply to the maxillary sinus. Clin Anat 12:417, 1999

30. Timmenga NM, Raghoebar GM, Liem RSB, et al: Effects ofaxillary sinus floor elevation surgery on maxillary sinus physi-ology. Eur J Oral Sci 111:189, 2003

31. Kleinheinz J, Buchter A, Kruse B, et al: Incision design inimplant dentistry based on vascularization of the mucosa. ClinOral Implant Res 16:518, 2005

1438 COMPLICATIONS IN MAXILLARY SINUS FLOOR ELEVATION PROCEDURES

Anatomical and Surgical Findings and Complications in 100 Consecutive Maxillary Sinus Floor Elevation ProceduresPatients and MethodsResultsDiscussionANATOMICAL FINDINGSThin or Thick Lateral Maxillary Sinus WallConvex Lateral Sinus WallConnection Between the Schneiderian Membrane and Oral MucosaThe Narrow and Wide SinusMaxillary Sinus SeptaLongitudinal SeptumRoot-Shape Configurations

SURGICAL FINDINGSMaxillary Sinus-Membrane PerforationHemorrhagesPostoperative Maxillary SinusitisLocal Wound Dehiscences

References