A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an...

A systematic review of the survival andcomplication rates of implant supportedfixed dental prostheses with cantileverextensions after an observation period ofat least 5 years

Marco AgliettaVincenzo Iorio SicilianoMarcel ZwahlenUrs BraggerBjarni E. PjeturssonNiklaus P. LangGiovanni E. Salvi

Authors’ affiliations:Marco Aglietta, Urs Bragger, Giovanni E. Salvi,University of Bern, School of Dental Medicine,Bern, SwitzerlandVincenzio Iorio Siciliano, Department ofPeriodontology, University of Naples, Naples, ItalyMarcel Zwahlen, Research Support Unit, Instituteof Social and Preventive Medicine, University ofBern, Bern, SwitzerlandBiarni E. Pjetrusson, Department of ReconstructiveDentistry, University of Iceland, Reykjavik, IcelandNiklaus P. Lang, University of Hong Kong, PrincePhilip Dental Hospital, Hong Kong, China

Correspondence to:Giovanni E. SalviDepartment of PeriodontologySchool of Dental MedicineUniversity of BernFreiburgstrasse 7CH-3010 Bern, SwitzerlandTel.: þ 4131 632 3551Fax: þ 4131 632 4915e-mail: giovanni.salvi@zmk.unibe.ch

Key words: biological complication, bone loss, cantilevers, dental implant, extensions,

fractures, peri-implantitis, success rate, survival rate, systematic review, technical complication

Abstract

Objective: The aim of this systematic review was to assess the survival rates of short-span

implant-supported cantilever fixed dental prostheses (ICFDPs) and the incidence of technical

and biological complications after an observation period of at least 5 years.

Material and methods: An electronic MEDLINE search supplemented by manual searching

was conducted to identify prospective or retrospective cohort studies reporting data of at

least 5 years on ICFDPs. Five- and 10-year estimates for failure and complication rates were

calculated using standard or random-effect Poisson regression analysis.

Results: The five studies eligible for the meta-analysis yielded an estimated 5- and 10-year

ICFDP cumulative survival rate of 94.3% [95 percent confidence interval (95% CI): 84.1–98%]

and 88.9% (95% CI: 70.8–96.1%), respectively. Five-year estimates for peri-implantitis were

5.4% (95% CI: 2–14.2%) and 9.4% (95% CI: 3.3–25.4%) at implant and prosthesis levels,

respectively. Veneer fracture (5-year estimate: 10.3%; 95% CI: 3.9–26.6%) and screw

loosening (5-year estimate: 8.2%; 95% CI: 3.9–17%) represented the most common

complications, followed by loss of retention (5-year estimate: 5.7%; 95% CI: 1.9–16.5%) and

abutment/screw fracture (5-year estimate: 2.1%; 95% CI: 0.9–5.1%). Implant fracture was rare

(5-year estimate: 1.3%; 95% CI: 0.2–8.3%); no framework fracture was reported.

Radiographic bone level changes did not yield statistically significant differences

either at the prosthesis or at the implant levels when comparing ICFDPs with short-span

implant-supported end-abutment fixed dental prostheses.

Conclusions: ICFDPs represent a valid treatment modality; no detrimental effects can be

expected on bone levels due to the presence of a cantilever extension per se.

The number of patients asking for fixed

implant-supported reconstructions has in-

creased considerably in the past few years

(Bornstein et al. 2008). This therapy is

often limited by financial costs, and also

by clinical situations such as bone defi-

ciencies and/or the presence of anatomical

structures (i.e. maxillary sinus, mental

foramen) in areas where implants have to

be ideally (prosthetically) placed. To treat

such patients, a number of surgical proce-

dures, such as guided bone regeneration

and sinus floor elevation, have been devel-

oped (Boyne & James 1980; Dahlin et al.

1988, 1989, 1991; Lundgren & Nyman

1991; Summers 1994a, 1994b). The in-

creasing cost and morbidity of complex

dental treatment using such approaches,

together with a number of related complica-

tions, may limit the choice of complex

treatment in daily practice (Simion et al.

1995; Chiapasco et al. 2006). An alternative

Date:Accepted 12 December 2008

To cite this article:Aglietta M, Siciliano VI, Zwahlen M, Bragger U,Pjetursson BE, Lang NP, Salvi GE. A systematic reviewof the survival and complication rates of implantsupported fixed dental prostheses with cantileverextensions after an observation period of at least 5 years.Clin. Oral Impl. Res. 20, 2009; 441–451.doi: 10.1111/j.1600-0501.2009.01706.x

c� 2009 John Wiley & Sons A/S 441

would be the use of fixed dental prostheses

with cantilever extensions that allow a

more straightforward rehabilitation of

edentulous areas (Rodriguez et al. 1994a,

1994b; Shackleton et al. 1994).

In a systematic review on short-span

tooth-supported fixed dental prostheses

(FDPs) with cantilever extensions (Pjeturs-

son et al. 2004b), a meta-analysis showed

low survival and success rates for these

FDPs after a period of 5 and 10 years. In

particular, this therapy was less predict-

able, when compared with other treatment

options, such as single-unit crowns on

implants and tooth- or implant-supported

FDPs (Pjetursson et al. 2004a; Tan et al.

2004; Jung et al. 2008).

In implant-supported FDPs with cantile-

ver extensions (ICFDPs) the distribution of

masticatory forces appeared not to be uni-

formly distributed. Higher strain concen-

trations at the implant sites, especially at

the level of the implant–bone interface

adjacent to the extension, were noted (Ro-

driguez et al. 1993; White et al. 1994;

Rangert et al. 1995; Sertgoz & Guvener

1996; Barbier et al. 1998; Stegaroiu et al.

1998; Akca & Iplikcioglu 2002). Conse-

quently, a higher incidence of complica-

tions was expected for implant-supported

cantilever FDPs. Moreover, it has been

postulated that the presence of excessive

force concentrations may also lead to bone

loss around implants (Lindquist et al. 1988;

Isidor 1996, 1997). Such excessive forces

may lead to micro-fractures within the

bone in areas of major strain concentra-

tions, where the pressure applied might

exceed the potential for bone repair (Frost

2004).

Clinical studies reported conflicting re-

sults for medium- and long-term outcomes

of ICFDPs. Comparing ICFDPs with im-

plant-supported FDPs without cantilever

extensions (IFDPs), Romeo et al. (2003)

reported an overall implant survival rate

of 97% and a prosthesis success rate of

98% during a follow-up period of 1–7

years. The survival rates were similar for

both treatments and, hence, it was con-

cluded that ICFDPs represented a predict-

able therapy. On the other hand, Nedir

et al. (2006) reported a higher number of

complications for ICFDPs compared with

those encountered for IFDPs (29.4% vs.

7.9%). Differences in the study protocol,

populations treated and prosthesis design

may explain these controversies. From the

analysis of the two studies (Romeo et al.

2003; Nedir et al. 2006), the long-term

predictability of reconstructions on im-

plants applying cantilevers remains un-

clear.

Hence, the objective of this systematic

review was to obtain robust estimates of 5

and 10 years of survival and complication

rates of short-span ICFDPs.

Materials and methods

Search strategy and inclusion criteria

A systematic review of the English litera-

ture was conducted for selected articles

published up to December 2007.

Searching was performed using an elec-

tronic database (Medline, PubMed). The

following key word combinations were

applied: ‘implants’ and ‘fixed partial den-

tures’, ‘implants’ and ‘bridges’, ‘implants’

and ‘fixed dental prostheses’, ‘implants’

and ‘partial edentulism’, ‘implants’ and

‘complications’, ‘implants’ and ‘failures’,

‘implants’ and ‘cantilever’, ‘implants’ and

‘extension’.

Moreover, hand-searching of the follow-

ing journals was undertaken from 2005 to

December 2007: Clinical Oral Implants

Research, International Journal of Perio-

dontics and Restorative Dentistry, Journal

of Periodontology, Journal of Clinical

Periodontology and International Journal

of Oral and Maxillofacial Implants. The

bibliographies from the selected articles

were screened systematically.

The objective of the search was to screen

the literature for prospective or retrospec-

tive longitudinal cohort studies or con-

trolled studies reporting on ICFDPs with a

mean follow-up period of at least 5 years. A

clinical examination had to be performed at

the end of the follow-up. Publications re-

porting only on patients’ records, question-

naires or interviews were excluded. If

multiple publications reporting on the

same population were found, only the

most recent report was included.

Study selection

Titles and abstracts were initially screened

by two independent reviewers (V.I.S. and

G.E.S.) for possible inclusion. The full-text

analysis of studies of relevance was con-

ducted independently by the reviewers and

disagreement was resolved by discussion.

Agreement between the reviewers was de-

termined using K statistics (Fig. 1).

Data for the meta-analysis were ex-

tracted by two independent reviewers

(M.A. and V.I.S.) and compared. Disagree-

ments were solved by discussion and by

contacting the authors of the original pub-

lications.

Excluded studies

From an original yield of 1370 titles and

412 abstracts, 98 were selected for the full-

text analysis; one publication was found as

a result of the manual search. Ninety-four

First electronic search1370

Potentially relevant abstracts retrieved for evaluation: 412

Full-text analysis98

Independently selected abstracts forfull-text analysis by 2 reviewers: 108

Final number ofstudies included

Kappa score0.94

Discussion discarded10 abstracts

Manual search1

Publications excludedon the basis of the

abstract:304

Publications excludedon the basis of the title:

Publications excludedon the basis of the full-

text analysis: 94

Fig. 1. Search strategy for implant supported, cantilever fixed dental prostheses (ICFDPs).

Aglietta et al . Implants with cantilever extensions

442 | Clin. Oral Impl. Res. 20, 2009 / 441–451 c� 2009 John Wiley & Sons A/S

publications were excluded because of the

following reasons: Mean observation period

o5 years, no specific data on ICFDPs and

publications reporting data from the same

cohort more than once.

Data extraction

Informations regarding survival and com-

plication rates of both implants and

ICFDPs were extracted. Implant survival

were considered if the implant was present

at the follow-up examination; ICFDP sur-

vival was considered if the prosthesis was

present at the follow-up visit without any

modifications.

Peri-implantitis and soft tissue compli-

cations were included in the category of

biological complications.

As for technical complications, all the

events affecting the implant and/or the

meso- and/or the supra-structures’ integ-

rity were considered. Among them, the

following categories were defined: implant

fractures, veneer fractures, framework frac-

tures, abutment or screw fractures, loss of

retention and screw loosening.

Statistical analysis

By definition, failure and complication

rates are calculated by dividing the number

of events (failures or complications) in the

numerator by the total exposure time

(ICFDP time or implant time) in the de-

nominator.

The numerator could usually be ex-

tracted directly from the publication or

was provided by the authors of the original

papers in cases in which only a part of the

full sample was taken into consideration.

The exposure time was extracted and

calculated by multiplying the mean

follow-up time by the number of implants

or ICFDPs available for the statistical ana-

lysis. The mean follow-up was directly

extracted from the articles (Halg et al.

2008), supplemented as adjunctive infor-

mation from the author of the original

papers (Wennstrom et al. 2004; Eliasson

et al. 2006; Kreissl et al. 2007) or calcu-

lated from the original database (Bragger

et al. 2005). Implants or ICFDPs available

for the analysis were defined as all the

fixtures or prostheses, respectively, from

which information was available relative to

the issues considered.

For each study, event rates for ICFDPs

and/or for implants were calculated by

dividing the total number of events by the

total ICFDPs’ or implants’ exposure time

in years. For further analysis, the total

number of events was considered to be

Poisson distributed for a given sum of

implant exposure years, and Poisson re-

gression with a logarithmic link function

and total exposure time per study as an

offset variable was used (Kirkwood &

Sterne 2003a, 2003b). To assess the het-

erogeneity of the study-specific event rates,

the Spearman goodness-of-fit statistics and

associated P-values were calculated. If the

goodness-of-fit P-value was o0.05, indi-

cating heterogeneity, random-effects Pois-

son regression (with g-distributed random

effects) was used to obtain a summary

estimate of the event rates. Five- and 10-

year survival proportions were calculated

via the relationship between event rate

and survival function S, S(T)¼ exp(�T

� event rate), by assuming constant event

rates (Kirkwood & Sterne 2003a, 2003b).

Ninety-five percent confidence intervals of

the summary estimates of the event rates

obtained from the Poisson regression were

reported. The 95% CIs for the survival

probabilities were obtained using the 95%

confidence limits from the summary event

rates.

For the analysis of the reported radio-

graphic bone loss, the mean difference

between FDPs with and without cantile-

vers and its standard error was calculated

for each study. These study-specific differ-

ences were then meta-analysed using the

inverse-variance weighting method.

All analyses were performed using Statas

(Stata Corporation, College Station, TX,

USA), version 10.

Results

Included studies

Figure 1 shows the process of identifying

the five studies finally included from an

initial yield of 1370 titles. Descriptive data

relative to the included five studies are

reported in Table 1. Only two studies

were specifically designed to test ICFDPs

(Wennstrom et al. 2004; Halg et al. 2008),

whereas for the other three studies, data on

ICFDPs were extracted from the original

samples composed predominantly of end-

abutment, implant-supported FDPs (Brag-

ger et al. 2005; Eliasson et al. 2006; Kreissl

et al. 2007).

Out of the five included publications,

two were prospective cohort studies (Brag-

ger et al. 2005; Kreissl et al. 2007), one was

a retrospective cohort study (Eliasson et al.

Table 1. Study and patient’s characteristics of the reviewed publications

Study(year ofpublication)

Studydesign

Implantsystem

Characteristicsof implantsystems

No. ofpatients

Mean ageof patients(years)

Age rangeof patients(years)

Setting

Wennstromet al. (2004)

Retrospectivecontrolled

Astra Techs

Dental ImplantSystem

Self-tapping screws,machined or tioblast

28 57 NR University

Bragger et al.(2005)

Prospective StraumannDental ImplantSystem

Solid screw, hollowscrew, hollow cylinder

14 42.9 20–78 University

Eliasson et al.(2006)

Retrospective BranemarkSystem

Turned surface NR NR NR University

Kreissl et al.(2007)

Prospective 3i Osseotites

Osseotite, hollowscrew

20 NR NR University

Halg et al.(2008)

Retrospectivecontrolled

StraumannDental ImplantSystem

Solid screw, hollowscrew, hollow cylinder

27 61.9 44–83 Privatepractice

NR, not reported.

c� 2009 John Wiley & Sons A/S 443 | Clin. Oral Impl. Res. 20, 2009 / 441–451

2006) and two were retrospective con-

trolled studies (Wennstrom et al. 2004;

Halg et al. 2008). The number of patients

was reported in four studies and ranged

between 14 and 28. The publication by

Eliasson et al. (2006) did not report the

number of patients receiving ICFDPs

(Table 1). Only one study was conducted

in a private practice (Halg et al. 2008),

whereas all the other studies were con-

ducted in an institutional environment

(e.g. university) (Table 1). Four different

commercially available implant systems

were used: Wennstrom et al. (2004) used

the Astra Techs

Dental Implant System

(Astra, Moelndal, Sweden), Eliasson et al.

(2006) the Branemark Systems

(Nobel

Biocare AB, Goteborg, Sweden), Kreissl

et al. (2007) the Osseotites

(3i-Implant

Innovations, West Palm Beach, FL, USA)

and Bragger et al. (2005) and Halg et al.

(2008) the Straumann Dental Implant

Systems

(Institut Straumann AG, Basel,

Switzerland). The implants used were

mostly solid screws. However, hollow

screws and hollow cylinders were reported

in three (Bragger et al. 2005; Kreissl et al.

2007; Halg et al. 2008) and two studies

(Bragger et al. 2005; Halg et al. 2008),

respectively (Table 1).

The studies reported on a total of 420

implants and 180 ICFDPs, of which 354

and 155 were available for the final analy-

sis, respectively (Table 2). The ICFDPs

were located in both the upper and the

lower jaws. All possible cantilever exten-

sion designs were used (e.g. distal, mesial

and distalþmesial). Unfortunately, it was

not possible to separate the data with

respect to the location and the prosthetic

design of the ICFDPs.

Three studies (Wennstrom et al. 2004;

Bragger et al. 2005; Halg et al. 2008) re-

ported on the number of crown units in

relation to the number of implants: the

mean value ranged between 1.60 and 1.84.

This, in turn, means that there were slightly

more than three units per two implants.

In three studies, ICFDPs were screw

retained and in one they were cemented;

Bragger and colleagues (2005) used both

retention systems (Table 2).

The follow-up period varied between the

studies. Three publications reported a fol-

low-up of 5 years (Wennstrom et al. 2004;

Kreissl et al. 2007; Halg et al. 2008),

whereas two publications included a

follow-up of 10 years (Bragger et al. 2005;

Eliasson et al. 2006).

Implant survival

Only data relative to post-loading implant

survival rates (e.g. failures that occurred

after loading, without accounting for im-

plants lost during the initial healing period)

were available. Early failures could not be

considered in the meta-analysis (Table 3).

Overall, from the 354 implants available

for analysis, eight implant losses occurred.

In the publications reporting 5-year results

(Wennstrom et al. 2004; Kreissl et al. 2007;

Halg et al. 2008), five losses were regis-

tered. Two of these were related to implant

fractures and one was the consequence of

advanced peri-implantitis. The reasons for

the loss of the remaining two implants

were not specified.

Bragger et al. (2005) and Eliasson et al.

(2006) reported data after 10 years of follow-

up. Three implants out of 181 were lost: one

due to an implant fracture and two due to

the sequellae of advanced peri-implantitis.

The estimated annual failure rate ranged

between 0.13 and 0.87, with a summary

estimate of 0.29 (95% CI: 0.15–0.59)

(Table 3).

The summary estimate of the implant

survival after 5 and 10 years was calculated

with a standard Poisson regression analysis

and amounted to 98.5% (95% CI: 97.1–

99.3%) and 97.1% (95% CI: 94.3–98.5%),

respectively (Table 3).

ICFDPs survival

The survival rate of ICFDPs was defined

as the prostheses remaining in situ

without any modifications during the ob-

servation time. Table 4 summarizes the

outcomes with respect to ICFDP failure

and survival rates.

Of 155 ICFDPs followed for at least 5

years, nine were known to be lost as a

consequence of implant loss and abut-

ment or supra-structure fracture or loss of

retention.

The study-specific estimated 5-year

survival rate varied between 91.5% and

The estimated annual failure rate per 100

ICFDP years ranged from 0 to 2.22 with

a summary estimate of 1.18 (95% CI:

0.40–3.45).

The estimated survival proportion after 5

and 10 years was derived from a standard

Poisson regression analysis and was 94.3%

(95% CI: 84.1–98%) and 88.9% (95% CI:

70.8–96.1%), respectively.

Biological complications

Biological complications are summarized

in Table 5. Outcomes relative to biological

Table 2. General informations on implants and ICFDPs in the selected studies

Totalno. ofimplantsplaced

No. ofimplantsavailablefor analysis

Totalno. ofICFDPsplaced

No. ofICFDPsavailablefor analysis

Ratiocrownunits/implants

Implantlength(mean orrange; mm)

Implantdiameters

Type ofextention

Locationof recons-tructions

Mechanismof retention

71 66 28 26 1.6 12.7 NR Distal 16 maxilla,8 mandible

Screwretained

Braggeret al. (2005)

33 33 18 18 1.84 NR NR 16 mesial,6 distal

11 maxilla,7 mandible

5 screwretained,13 cemented

Eliassonet al. (2006)

209 148 84 61 NR NR NR Mesial, distal,bilateral

NR Screwretained

61 61 23 23 NR NR NR 18 mesial,15 distal

Maxilla andmandible

Screwretained

Halg et al.(2008)

46 46 27 27 1.65 6–12 3.3 or 4.1 12 mesial,15 distal

13 maxilla,14 mandible

Cemented

ICFDPs, implant supported, cantilever fixed dental prostheses; NR, not reported.

complications were reported in only two

publications (Bragger et al. 2005; Halg

et al. 2008). Soft tissue complications

(e.g. peri-implant mucositis or soft tissue

recession) were not reported systemati-

cally, and only data on peri-implantitis

were available.

Bragger et al. (2005) defined peri-implan-

titis as probing-pocket depth (PPD)

� 5 mm and bleeding on probing (BOP),

with five implants being affected during

9.4 years of follow-up. Halg et al. (2008)

reported one peri-implatitis case without

providing a specific definition of the diag-

nostic parameters adopted.

On an implant level, these data

yielded a summary estimate for bio-

logical complications of 1.11 (95% CI:

0.4–3.06) per 100 implant years using

standard Poisson regression analysis. The

cumulative complication rate after 5 and

10 years was 5.4% (95% CI: 2–14.2%)%

and 10.5% (95% CI: 3.9–26.4), respec-

tively.

On the prosthesis level, the summary

estimate for biological complications

amounted to 1.97 (95% CI: 0.66–5.8%)

per 100 years, resulting in 9.4% (95% CI:

3.3–25.4%) of ICFDPs showing a biological

complication after 5 and 17.9% (95% CI:

6.4–44.3) after 10 years of function, respec-

tively (Table 5).

Technical complications

Technical complications were defined as

damage to the integrity of the implants or

of the meso- and suprastuctures.

The outcomes of implant fractures are

reported in Table 6a. One study did not

provide informations about implant frac-

tures (Wennstrom et al. 2004), two studies

registered three fractures (Bragger et al.

2005; Halg et al. 2008) and other two

studies reported no fractures at all (Eliasson

et al. 2006; Kreissl et al. 2007). More

Table 3. Annual failure rates and survival of implants

Totalno. ofimplantsplaced

Meanfollow-uptime(years)

No. offailures

Totalimplantsexposuretime

Estimatedfailure rate(per 100implant years)

Estimatedsurvival rateafter 5 years(%)

71 66 5 2 330 0.61 97% 94.1

33 33 9.4 1 310.2 0.32 98.4 96.8

209 148 10.5 2 1459.5 0.13 99.4 98.7

61 61 5 1 305 0.33 98.4 96.8

Halg et al.(2008)

46 46 5 2 230 0.87 95.7 91.7

Total 420 354 8Summaryestimate(95% CI)n

0.29(0.15–0.59)

98.5(97.1–99.3)

97.1(94.3–98.5)

nBased on Poisson regression, test for heterogeneity, P¼ 0.27.

CI, confidence interval.

Table 4. Annual failure rates and survival of ICFDPs

Totalno. ofICFDPsplaced

No. ofICFDPsavailable foranalysis

No. offailures

TotalICFDPsexposuretime

Estimatedfailure rate(per 100 ICFDPyears)

Estimatedsurvivalrate after10 years (%)

28 26 5 2 130 1.54 92.6 85.7

18 18 9.4 3 169.2 1.77 91.5 83.8

84 61 10.5 0 640.5 0 100 100%

23 23 5 1 115 0.87 95.7 91.7

Halg et al.(2008)

27 27 5 3 135 2.22 89.5 80.1

Total 180 155 9Summaryestimate(95% CI)n

1.18(0.4–3.45)

94.3(84.1–98)

88.9(70.8–96.1)

nBased on random effects Poisson regression, test for heterogeneity, P¼ 0.02.

ICFDPs, implant supported cantilever fixed dental prostheses; CI, confidence interval.

specifically, Halg et al. (2008) reported two

events related to reduced diameter im-

plants (e.g. 3.3 mm in diameter), whereas

Bragger et al. (2005) noted the fracture of

one hollow cylinder implant.

Based on these outcomes, the summary

estimate for implant fractures per 100 im-

plant years was 0.25 (95% CI: 0.04–1.73),

resulting in cumulative implant fracture

rates after 5 and 10 years of 1.3% (95%

CI: 0.2–8.3%) and 2.5% (95% CI: 0.4–

15.8%), respectively (Table 6a).

Technical complications related to su-

prastructure components are reported in

Tables 6b and 6c.

Veneer fractures represented the most

frequent technical complication. They

were reported in every study, with a total

of 16 cases. The statistical analysis re-

vealed a summary estimate of veneer frac-

tures per 100 patient years of 2.18 (95%

CI: 0.80–5.93) (Table 6b).

Abutment or screw fractures were re-

ported in three studies (Bragger et al.

2005; Eliasson et al. 2006; Kreissl et al.

2007), whereas two studies (Wennstrom

et al. 2004; Halg et al. 2008) did not report

such an event. In a standard Poisson regres-

sion analysis, the estimated cumulative

rate of screw or abutment fractures over

an observation period of 5 and 10 years was

2.1% (95% CI: 0.9–5.1%) and 4.1% (95%

CI: 1.7–9.7%), respectively (Table 6b).

No framework fractures were reported in

any of the included publications (Table 6b).

In two studies, the prostheses were cemen-

ted (Bragger et al. 2005; Halg et al. 2008).

The meta-analysis resulted in an estimated

cumulative rate of loss of retention over

an observation period of 5 and 10 years

of 5.7% (95% CI: 1.9–16.5%) and

11.1% (95% CI: 3.7–30.3%), respectively

(Table 6c).

Screw-retained ICFDPs were reported in

four studies (Table 6c). Random-effect

Poisson regression analysis revealed an es-

timated cumulative rate of screw loosening

over an observation period of 5 and 10 years

of 8.2% (95% CI: 3.9–17%) and 15.7%

(95% CI: 7.6–31%), respectively.

Radiographic bone-level changes

Bone loss was reported in two studies

(Table 7; Wennstrom et al. 2004; Halg

et al. 2008). In both, radiographic bone-

level changes around implants supporting

prostheses with cantilever extensions were

compared with implant-supported FDPs

without cantilever extensions (IFDPs).

Table 5. Biological complications

Meanfollow-up(years)

No. ofbiologicalcomplications

Estimatedimplantcomplicationrate (per 100implant years)

EstimatedICFDPcomplicationrate (per 100prostheses years)

Bragger et al. (2005) 33 18 9.4 310.2 169.2 5 1.61 2.96Halg et al. (2008) 46 27 5 230 135 1 0.43 0.74Total 79 45 6Summary estimate(95% CI)n

1.11(0.4–3.06)

1.97(0.67–5.84)

Cumulative 5-yearcomplication rates(95% CI)

5.4%(2–14.2%)

9.4%(3.3–25.4%)

10.5%(3.9–26.4)

17.9%(6.4–44.3)

nBased on Poisson regression, test for heterogeneity, P¼ 0.20 (implant years), 0.17 (prostheses years).

CI, confidence interval.

Table 6a. Technical complications: implant related complications

Study (year ofpublication)

No. ofimplantsavailable foranalysis

Meanfollow-up time(years)

No. ofimplantfractures

Estimated rate ofimplant fractures(per 100 implant years)

Bragger et al. (2005) 33 9.4 310.2 1 0.32Eliasson et al. (2006) 148 10.5 1554 0 0Kreissl et al. (2007) 61 5 305 0 0Halg et al. (2008) 46 5 230 2 0.87Total 288 3Summary estimate (95% CI)n 0.25

(0.04–1.73)Cumulative 5-year implantfracture rates (95% CI)

1.3%(0.2–8.3%)

Cumulative 10-year implantfracture rates (95% CI)

2.5%(0.4–15.8%)

nBased on random effects Poisson regression, test for heterogeneity, P¼ 0.004.

Table 6b. Technical complications: fractures of meso- and suprastructure components

No. ofveneersfractures

Estimatedrate ofveneerfractures(per 100patients/year)

No. offrameworkfractures

Estimatedrate offrameworkfractures(per 100patients/year)

No. ofabutmentor screwfractures

Estimatedrate ofabutmentor screwfractures(per100 patients/year)

Wennstrom et al.(2004)

24 5 120 1 0.83 0 0 0

18 9.4 169.2 1 0.59 0 1 0.59

61 10.5 640.5 2 0.31 0 3 0.47

23 5 115 8 6.96 0 1 0.87

Halg et al.(2008)

27 5 135 4 2.96 0 0 0

Total 153 16 0 5Summaryestimate(95% CI)n

2.18(0.8–5.93%)

– 0.42(0.18–1.02)

Cumulative5-yearcomplicationrates (95% CI)

10.3%(3.9–26.6%)

– 2.1%(0.9–5.1%)

Cumulative10-yearcomplicationrates (95% CI)

19.6%(7.7–44.7%)

– 4.1%(1.7–9.7%)

nBased on random effects Poisson regression, test for heterogeneity Po0.001 for veneers fractures.

Based on Poisson regression, test for heterogeneity P¼ 0.78 for abutment screw fractures.

Table 6c. Technical complications: loss of retention and screw loosening

No. ofcementedICFDPsavailablefor lossof retentionanalysis

TotalcementedICFDPsexposuretime

No. ofcases ofloss ofretention

Estimatedrate of lossof retention(per 100ICFDP year)

No. of screw-retainedICFDPsavailablefor screwlooseninganalysis

TotalscrewretainedICFDPsexposuretime

No. ofcasesscrewloosening

Estimatedrate of screwloosening(per 100screw retainedICFDP year)

Wennstrom et al.(2004)

– – – – – 24 5 120 2 1.67

13 9.4 122.2 2 1.64 5 9.4 47 0 0

– – – – – 61 10.5 640.5 7 1.09

– – – – – 23 5 115 5 4.35

Halg et al.(2008)

27 5 135 1 0.74 – – – – –

Total 40 3 113 14Summary estimate(95% CI)n

1.17(0.38–3.62)

1.71(0.79–3.72)

5.7%(1.9–16.5%)

8.2%(3.9–17%)

Cumulative 10-year complicationrates (95% CI)

11.1%(3.7–30.3%)

15.7%(7.6–31%)

nBased on Poisson regression, test for heterogeneity, P¼ 0.51 for loss of retention.

Based on random effects Poisson regression, test for heterogeneity P¼ 0.06 for loss of retention or screw loosening.

At the prosthesis level, meta-analysis

revealed an estimated mean difference in

radiographic bone loss per year of 0.025

(95% CI: � 0.023–0.073) in favour of

IFDPs. This difference, however, did not

reach statistical significance (P¼ 0.31).

The same analysis was conducted by

comparing the radiographic bone loss

around fixtures in the proximity of canti-

lever extensions with control implants

supporting FDPs without cantilever exten-

sions. The radiographic bone level changes

resulted in slightly greater bone loss around

implants in the proximity of cantilever

extensions. However, no statistically sig-

nificant difference was found, with a sum-

mary estimate of difference in bone loss per

year of 0.033 (95% CI: � 0.02–0.087;

P40.05) (Table 8).

Discussion

This review is part of a series of systematic

reviews aiming at the evaluation of the

published literature with respect to fixed

reconstructions. The aim of these reviews

was to provide an overview of the types and

incidences of complications related to var-

ious reconstruction designs and to compare

their relative survival and complication

rates. The outcomes of the present sys-

tematic review showed that short-span

FDPs with cantilever extensions repre-

sented a predictable treatment modality.

No major detrimental effects with respect

to peri-implant tissues were observed at

extensions. It has to be noted, however,

that the majority of ICFDPs analysed in the

present systematic review were incorpo-

rated into premolar and molar areas.

In a meta-analysis on implant supported

reconstructions, an FDP survival rate of

95% after 5 years and an FDP success

rate of 61.3% were reported (Pjetursson

et al. 2004a). The outcomes of these sys-

tematic reviews were recently updated and

summarized in order to propose guidelines

for the choice of the type of reconstruction

to be preferred in different treatment situa-

tions (Pjetursson & Lang 2008). In this

respect, single-unit implant-supported

crowns should be considered as the gold

standard treatment in the rehabilitation of

single- or two-unit gaps (Jung et al. 2008).

Tooth-supported FDPs represent an alter-

native for the rehabilitation of edentulous

spaces where functional and/or aesthetic

aspects of the neighbouring teeth have to be

considered. Tooth- or implant-supported

FDPs were also shown to yield predictable

long-term outcomes, with estimated an-

nual failure rates of 1.14% and 1.43%,

respectively (Pjetursson et al. 2004a; Tan

et al. 2004). Tooth-implant-supported

FDPs (Lang et al. 2004), tooth-supported

FDPs with cantilever extensions (Pjeturs-

son et al. 2004b) and resin-bonded fixed

reconstructions (Pjetursson et al. 2008),

however, have to be considered as second

treatment options, as higher estimated an-

nual failure rates of 2.51%, 2.20% and

4.31%, respectively, can be expected.

In some clinical cases, none of the pre-

viously discussed fixed reconstructions

may be incorporated owing to the fact

that inadequate bone volume may be

Table 7. Radiographic bone loss around ICFDPs and IFDPs without cantilever extensions

No. ofICFDPs

Mean boneloss (SD)(mm)

Mean boneloss peryear (mm)

No. of IFDPswithoutcantilever

Mean boneloss (SD)(mm)

Mean boneloss peryear (mm)

Mean differencein bone lossper year (mm)

24 5 0.49(0.89)

0.1 23 5 0.38(0.65)

0.08 0.02

Halg et al.(2008)

24 5.3 0.23(0.63)

0.04 25 5.3 0.09(0.43)

0.02 0.03

Summaryestimate(95% CI)n

0.025(� 0.023–0.073)P-value¼ 0.31

nMeta-analysis of mean differences with P¼0.95 for heterogeneity.

ICFDPs, implant supported cantilever fixed dental prostheses; SD, standard deviation; CI, confidence interval.

Table 8. Radiographic bone loss around implants in proximity of cantilever extensions and control implants supporting FDPs withoutcantilever extensions

No. ofimplantsclose toextension

Meanboneloss (SD)(mm)

Meanbone lossper year(mm)

No. ofcontrols

Totalcontrolsexposuretime

Meanboneloss (SD)(mm)

Meanboneloss peryear (mm)

Meandifference inbone loss peryear (mm)

24 5 0.39(1.04)

0.08 23 5 115 0.23(0.67)

0.05 0.03

Halg et al.(2008)

24 5.3 0.23(0.71)

0.04 24 5.3 127.2 0.05(0.45)

0.01 0.03

Summaryestimate(95% CI)n

0.033(� 0.02–0.087)P-value¼ 0.14

nMeta-analysis of mean differences with P¼0.974.

SD, standard deviation; CI, confidence interval; FDP, fixed dental prosthesis.

diagnosed and/or the available abutments

may be located in strategically unfavour-

able positions. In such situations, the in-

sertion of one or more implants supporting

a cantilever extension may be a reasonable

treatment option.

The results of the present systematic

review revealed that ICFDPs are treatment

variations with high predictability and fa-

vourable long-term outcomes for the pa-

rially edentulous patient. The estimated

failure rate per 100 ICFDP years of 1.18

reported in the present systematic review is

comparable with that of implant-supported

FDPs (e.g. 1.03; Pjetursson et al. 2004a) or

conventional tooth-supported FDPs (e.g.

1.16; Tan et al. 2004).

Moreover, the estimated failure rate per

100 ICFDP years reported in the present

systematic review (e.g. 1.18) compared

more favourably with that of tooth-sup-

ported FDPs with cantilever extensions

(e.g. 2) (Pjetursson et al. 2004b), indicating

that cantilevers supported by implants may

yield lower complication rates than cantile-

vers supported by teeth. Furthermore, the

estimated failure rate per 100 ICFDP years

was substantially lower than that of com-

bined tooth-implant-supported FDPs (e.g.

2.51; Lang et al. 2004). The obvious clinical

advantages of ICFDPs include reduced treat-

ment time and cost, as well as the redun-

dancy of complex reconstructive surgeries.

Moreover, prosthetic reconstructions

like the placement of a single implant

supporting a distal or a mesial cantilever

extension have been propagated for the

restoration of two-unit single gaps in areas

of aesthetic priority. In such situations (i.e.

a missing lateral and central maxillary in-

cisors), the space for the insertion of two

adjacent implants with adequate distances

between them and the neighbouring teeth

is often lacking. Not respecting adequate

distances between implants and neighbour-

ing teeth may result in jeopardy of perio-

dontal structures (Krennmair et al. 2003),

or in increased bone resorption, with the

interdental papillae failing to develop be-

tween adjacent implants (Tarnow et al.

2000; Gastaldo et al. 2004). The placement

of one single implant supporting a mesial or

a distal cantilever extension may resolve

this problem. However, scientific evidence

for this concept is still lacking.

It has to be realized that in the studies

selected for the meta-analysis of this sys-

tematic review, a considerable variability

of outcomes was reported. In particular,

some studies showed impressively good

long-term results (Eliasson et al. 2006),

whereas other publications reported a

higher percentage of prostheses lost during

the follow-up (Halg et al. 2008). Such

discrepancies are also evident from out-

comes of publications reporting on

ICFDPs, but excluded from the present

systematic review. As an example, Becker

(2004) reported no complications in a retro-

spective study on 60 prostheses with can-

tilever extensions. Also, a 100% survival

rate was reported by Johansson & Ekfeldt

(2003) after the analysis of 65 ICFDPs

followed for a mean observation period of

49.6 months. In that study (Johansson &

Ekfeldt 2003), however, a higher complica-

tion rate was found for ICFDPs compared

with FDPs without cantilever extensions.

On the other hand, low survival and high

complication rates were reported in two

recent studies reporting on ICFDPs (De

Boever et al. 2006; Nedir et al. 2006).

The variety of results between the differ-

ent publications selected for the present

systematic review may be explained from

different aspects. First of all, the number of

implant-supporting ICFDPs could have an

effect on the survival and success of the

prostheses. In the papers selected for the

present systematic review, the number of

implants per prosthesis varied between one

and three. It has to be noted that studies

reporting on prostheses with two to three

implants (Eliasson et al. 2006) yielded

better results than studies reporting on

prostheses supported by one to two im-

plants (Halg et al. 2008).

The position of the cantilever extension

(e.g. mesial or distal or combined) as well

as the length of the cantilever beam (e.g.

one or more extension units) may also have

influenced the outcome. With the excep-

tion of the study by Wennstrom et al.

(2004), who only reported on distal canti-

lever extensions, all the other publications

reported on both types (mesial and distal) of

extension locations. Owing to the small

sample sizes of subgroups, separate ana-

lyses with respect to extension locations

could not be performed in the present

systematic review.

The length of distal cantilever extensions

(e.g. � or � 15 mm) was shown to

influence the survival rate of implant-

supported full-arch fixed prostheses

(Shackleton et al. 1994). In four publica-

tions (Bragger et al. 2005; Eliasson et al.

2006; Kreissl et al. 2007; Halg et al. 2008)

that reported on implant-related technical

complications, three implant fractures

were observed. These events were linked

to the use of hollow-body or reduced-dia-

meter implants. The fact that hollow-body

or diameter-reduced implants affected im-

plant survival (e.g. implant fracture) was

also reported for implant-supported FDPs

without cantilever extensions (Buser et al.

1997; Zinsli et al. 2004). As a conse-

quence, it has to be advocated to avoid

the use of diameter-reduced implants in

the proximity of cantilever extensions in

ICFDPs.

Two studies compared the 5-year out-

comes of ICFDPs and implant-supported

FDPs without cantilever extensions

(IFDPs) (Wennstrom et al. 2004; Halg

et al. 2008). Halg et al. (2008) reported a

difference in the survival rate of ICFDPs

and IFDPs (89.9% vs. 96.3%, Po0.05), as

well as a higher number of technical com-

plications in ICFDPs compared with

IFDPs. On the other hand, no difference

was reported between the two groups with

respect to implant failures and radiographic

bone-level changes. Similarly, Wennstrom

et al. (2004) reported comparable changes

in radiographic bone levels around implants

supporting ICFDPs with IFDPs.

The present meta-analysis has con-

firmed that no statistically significant dif-

ferences in bone-level changes were

observed between the ICFDPs and the

IFDPs. This is in accordance with the out-

comes reported by Blanes et al. (2007)

documenting the lack of influence of me-

sial or distal cantilever extensions on peri-

implant bone-level changes.

In conclusion, ICFDPs represent a pre-

dictable and reliable treatment for the re-

placement of posterior missing teeth in

partially edentulous patients. The most

frequent technical complications included

veneer fractures, followed by screw loosen-

ing and loss of retention. No detrimental

effects on bone levels were observed around

extensions.

To date, however, evidence of the effects

of various prosthetic designs (e.g. distal or

mesial cantilever extension), number of

implants supporting ICFDPs and occlusal

concepts on the incidence of complications

in ICFDPs is still sparse.

Acknowledgements: This study was

supported by the Clinical Research

Foundation (CRF) for the Promotion of

Oral Health, Brienz, Switzerland. The

first author is the recipient of an ITI

scholarship from the ITI Foundation for

Implantology, Basel, Switzerland.

Conflicts of interest: none declared.

References

Akca, K. & Iplikcioglu, H. (2002) Finite element

stress analysis of the effect of short implant usage

in place of cantilever extensions in mandibular

posterior edentulism. Journal of Oral Rehabilita-

tion 29: 350–356.

Barbier, L., Vander Sloten, J., Krzesinski, G., Sche-

pers, E. & Van der Perre, G. (1998) Finite element

analysis of non-axial versus axial loading of oral

implants in the mandible of the dog. Journal of

Oral Rehabilitation 25: 847–858.

Becker, CM. (2004) Cantilever fixed prostheses

utilizing dental implants: a 10-year retrospec-

tive analysis. Quintessence International 35:

437–441.

Blanes, R.J., Bernard, J.P., Blanes, Z.M. & Belser,

U.C. (2007) A 10-year prospective study of ITI

dental implants placed in the posterior region. II:

influence of the crown-to-implant ratio and dif-

ferent prosthetic treatment modalities on crestal

bone loss. Clinical Oral Implants Research 18:

707–714.

Bornstein, M.M., Halbritter, S., Harnisch, H., We-

ber, H.-P. & Buser, D. (2008) A retrospective

analysis of patients referred for implant placement

to a specialty clinic: indications, surgical proce-

dures and early failures. International Journal of

Oral & Maxillofacial Implants 23: 1109–1116.

Boyne, P.J. & James, R.A. (1980) Grafting of the

maxillary sinus floor with autogenous marrow

and bone. Journal of Oral Surgery 38: 613–616.

Bragger, U., Karoussis, I., Persson, R., Pjetursson,

B., Salvi, G. & Lang, N.P. (2005) Technical and

biological complications/failures with single

crowns and fixed partial dentures on implants: a

10-year prospective cohort study. Clinical Oral

Implants Research 16: 326–334.

Buser, D., Mericske-Stern, R., Bernard, J.P., Beh-

neke, A., Behneke, N., Hirt, H.P., Belser, U.C. &

Lang, N.P. (1997) Long-term evaluation of non-

submerged ITI implants. Part 1: 8-year life table

analysis of a prospective multi-center study with

2359 implants. Clinical Oral Implants Research

8: 161–172.

Chiapasco, M., Zaniboni, M. & Boisco, M. (2006)

Augmentation procedures for the rehabilitation of

deficient edentulous ridges with oral implants.

Clinical Oral Implants Research 17 (Suppl 2):

136–159.

Dahlin, C., Lekholm, U. & Linde, A. (1991) Mem-

brane-induced bone augmentation at titanium

implants. A report on ten fixtures followed from

1 to 3 years after loading. International Journal of

Periodontics and Restorative Dentistry 11: 273–

Dahlin, C., Linde, A., Gottlow, J. & Nyman, S.

(1988) Healing of bone defects by guided tissue

regeneration. Plastic Reconstructive Surgery 81:

672–676.

Dahlin, C., Sennerby, L., Lekholm, U., Linde, A. &

Nyman, S. (1989) Generation of new bone around

titanium implants using a membrane technique: an

experimental study in rabbits. International Journal

of Oral & Maxillofacial Implants 4: 19–25.

De Boever, A.L., Keersmaekers, K., Vanmaele, G.,

Kerschbaum, T., Theuniers, G. & De Boever, J.A.

(2006) Prosthetic complications in fixed endoss-

eous implant-borne reconstructions after an ob-

servations period of at least 40 months. Journal of

Oral Rehabilitation 33: 833–839.

Eliasson, A., Eriksson, T., Johansson, A. & Wenner-

berg, A. (2006) Fixed partial prostheses supported

by 2 or 3 implants: a retrospective study up to 18

years. International Journal of Oral & Maxillofa-

cial Implants 21: 567–574.

Frost, H.M. (2004) A 2003 update of bone physiol-

ogy and Wolff’s Law for clinicians. Angle Ortho-

dontist 74: 3–15.

Gastaldo, J.F., Cury, P.R. & Sendyk, W.R. (2004)

Effect of the vertical and horizontal distances

between adjacent implants and between a

tooth and an implant on the incidence of inter-

proximal papilla. Journal of Periodontology 75:

1242–1246.

Halg, G.A., Schmid, J. & Hammerle, C.H.F. (2008)

Bone level changes at implants supporting crowns

on fixed partial dentures with or without cantile-

vers. Clinical Oral Implants Research 19: 983–

Isidor, F. (1996) Loss of osseointegration caused by

occlusal load of oral implants. A clinical and

radiographic study in monkeys. Clinical Oral

Isidor, F. (1997) Histological evaluation of peri-im-

plant bone at implants subjected to occlusal over-

load or plaque accumulation. Clinical Oral

Johansson, L.A. & Ekfeldt, A. (2003) Implant-sup-

ported fixed partial prostheses: a retrospective

study. International Journal of Prosthodontics

16: 172–176.

Jung, R.E., Pjetursson, B.E., Glauser, R., Zembic,

A., Zwahlen, M. & Lang, N.P. (2008) A systema-

tic review of the 5-year survival and complication

rates of implant-supported single crowns. Clinical

Oral Implants Research 19: 119–130.

Kirkwood, B.R. & Sterne, J.A.C. (2003a) Essential

Medical Statistics, Chapter 24: Poisson Regres-

sion. Oxford: Blackwell Science Ltd., 249–262.

Kirkwood, B.R. & Sterne, J.A.C. (2003b) Displaying

and comparing survival patterns. In: Essential

Medical Statistics, Chapter 26: Survival

Analysis.. Oxford: Blackwell Science Ltd.,

272–286.

Kreissl, M.E., Gerds, T., Muche, R., Heydecke, G.

& Strub, J.R. (2007) Technical complications

of implant-supported fixed partial dentures in

partially edentulous cases after an average obser-

vation period of 5 years. Clinical Oral Implants

Research 18: 720–726.

Krennmair, G., Piehslinger, E. & Wagner, H. (2003)

Status of teeth adjacent to single-tooth implants.

International Journal of Prosthodontics 16: 524–

Lang, N.P., Pjetursson, B.E., Tan, K., Bragger, U.,

Egger, M. & Zwahlen, M. (2004) A systematic

review of the survival and complication rates of

fixed partial dentures (FDPs) after an observation

period of at least 5 years. II. Combined tooth –

implant-supported FDPs. Clinical Oral Implants

Research 15: 643–653.

Lindquist, L.W., Rockler, B. & Carlsson, G.E.

(1988) Bone resorption around fixtures in edentu-

lous patients treated with mandibular fixed

tissue-integrated prostheses. Journal of Prosthetic

Dentistry 59: 59–63.

Lundgren, D. & Nyman, S. (1991) Bone regenera-

tion in 2 stages for retention of dental implant. A

case report. Clinical Oral Implants Research 2:

203–207.

Nedir, R., Bischof, M., Szmukler-Moncler, S., Belser,

U.C. & Samson, J. (2006) Prosthetic compli-

cations with dental implants: from an up-to-8-year

experience in private practice. International

Journal of Oral & Maxillofacial Implants 21:

919–928.

Pjetursson, B.E. & Lang, N.P. (2008) Prosthetic

treatment planning on the basis of scientific

evidence. Journal of Oral Rehabilitation 35

(Suppl 1): 72–79.

Pjetursson, B.E., Tan, K., Lang, N.P., Bragger, U.,

Egger, M. & Zwahlen, M. (2004a) A systematic

period of at least 5 years. Clinical Oral Implants

Research 15: 625–642.

Pjetursson, B.E., Tan, K., Lang, N.P., Bragger, U.,

Egger, M. & Zwahlen, M. (2004b) A systematic

period of at least 5 years. Clinical Oral Implants

Research 15: 667–676.

Pjetursson, B.E., Tan, W.C., Tan, K., Bragger, U.,

Zwahlen, M. & Lang, N.P. (2008) A systematic

resin-bonded bridges after an observation period of

at least 5 years. Clinical Oral Implants Research

19: 131–141.

Rangert, B., Krogh, P.H., Langer, B. & Van Roekel,

N. (1995) Bending overload and implant fracture:

a retrospective clinical analysis. International

Journal of Oral & Maxillofacial Implants 10:

326–334.

Rodriguez, A.M., Aquilino, S.A. & Lund, P.S.

(1994a) Cantilever and implant biomechanics:

a review of the literature. Part 1. Journal of

Prosthodontics 3: 41–46.

Rodriguez, A.M., Aquilino, S.A. & Lund, P.S.

(1994b) Cantilever and implant biomechanics: a

review of the literature, part 2. Journal of Prostho-

dontics 3: 114–118.

Rodriguez, A.M., Aquilino, S.A., Lund, P.S., Ryther,

J.S. & Southard, T.E. (1993) Evaluation of strain at

the terminal abutment site of a fixed mandibular

implant prosthesis during cantilever loading. Jour-

nal of Prosthodontics 2: 93–102.

Romeo, E., Lops, D., Margutti, E., Ghisolfi, M.,

Chiapasco, M. & Vogel, G. (2003) Implant-sup-

ported fixed cantilever prostheses in partially eden-

tulous arches. A seven-year prospective study.

Clinical Oral Implants Research 14: 303–311.

Sertgoz, A. & Guvener, S. (1996) Finite element

analysis of the effect of cantilever and implant

length on stress distribution in an implant-sup-

ported fixed prosthesis. Journal of Prosthetic Den-

tistry 76: 165–169.

Shackleton, J.L., Carr, L., Slabbert, J.C. & Becker,

P.J. (1994) Survival of fixed implant-supported

prostheses related to cantilever lengths. Journal

of Prosthetic Dentistry 71: 23–26.

Simion, M., Trisi, P., Maglione, M. & Piattelli, A.

(1995) Bacterial penetration in vitro through

GTAM membrane with and without topical

chlorhexidine application. A light and scanning

electron microscopic study. Journal of Clinical

Periodontology 22: 321–331.

Stegaroiu, R., Sato, T., Kusakari, H. & Miyakawa,

O. (1998) Influence of restoration type on stress

distribution in bone around implants: a three-

dimensional finite element analysis. Interna-

tional Journal of Oral & Maxillofacial Implants

13: 82–90.

Summers, R.B. (1994a) A new concept in maxillary

implant surgery: the osteotome technique. Com-

pendium 15: 152–158.

Summers, R.B. (1994b) The osteotome technique:

part 3 – less invasive methods of elevating the

sinus floor. Compendium 15: 698–704.

Tan, K., Pjetursson, B.E., Lang, N.P. & Chan, E.S.

(2004) A systematic review of the survival and

complication rates of fixed partial dentures

(FDPs) after an observation period of at least

5 years. Clinical Oral Implants Research 15:

654–666.

Tarnow, D.P., Cho, S.C. & Wallace, S.S. (2000) The

effect of inter-implant distance on the height of

inter-implant bone crest. Journal of Perio-

dontology 71: 546–549.

Wennstrom, J., Zurdo, J., Karlsson, S., Ekestubbe,

A., Grondahl, K. & Lindhe, J. (2004) Bone level

change at implant-supported fixed partial dentures

with and without cantilever extension after

5 years in function. Journal of Clinical Perio-

dontology 31: 1077–1083.

White, S.N., Caputo, A.A. & Anderkvist, T. (1994)

Effect of cantilever length on stress transfer by

implant-supported prostheses. Journal of Prosthe-

tic Dentistry 71: 493–499.

Zinsli, B., Sagesser, T., Mericske, E. & Mericske-

Stern, R. (2004) Clinical evaluation of small-

diameter ITI implants: a prospective study.

International Journal of Oral & Maxillofacial

Implants 19: 92–99.

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an...

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