does three-dimensional imaging offer a financial benefit for treating maxillary molars with...

Clemens WalterRoland WeigerThomas DietrichNiklaus P. LangNicola U. Zitzmann

Does three-dimensional imaging offera financial benefit for treatingmaxillary molars with furcationinvolvement? – A pilot clinical caseseries

Authors’ affiliations:Clemens Walter, Roland Weiger, Nicola U.Zitzmann, Department of Periodontology,Endodontology and Cariology, University of Basel,Basel, SwitzerlandClemens Walter, Thomas Dietrich, Department ofOral Surgery, School of Dentistry, University ofBirmingham, Birmingham, UKNiklaus P. Lang, The University of Hong Kong,Hong Kong SAR, China

Corresponding author:Nicola U. ZitzmannDepartment of Periodontology, Endodontology andCariologyUniversity of BaselHebelstrasse 3, 4056 Basel, SwitzerlandTel.: +41 61 2672613Fax: +41 61 2672659e-mail: [email protected]

Key words: 3D imaging, cone beam computed tomography, cost benefit analysis, maxillary

furcation surgery

Abstract

Aim: To assess the financial benefit of cone beam computed tomography (CBCT) for the treatment

options of maxillary molars including periodontal surgery and extraction followed by implant

placement.

Material and methods: Twelve patients with generalized chronic periodontitis were recruited, and

CBCT was performed in maxillary molars (n = 22) with clinical furcation involvement and increased

probing pocket depths. Treatment recommendations were either based on conventional

periodontal diagnostics (clinical examinations and periapical radiographs), or based on the

additional CBCT data. Clinical recommendations comprised a minimal (e.g. supportive periodontal

treatment) and a maximal invasive therapy (e.g. extraction and implant placement), and these

were compared with CBCT-based recommendations. According to the Swiss dental tariff structure,

the probabilities of saving costs or time, and the numbers needed to treat were analysed with an

empirical cumulative distribution function.

Results: Average cost reduction from CBCT amounted to CHF 915 ± 1470 and saved 136 ± 217 min.

Greatest reductions were found with maximal invasive clinically based treatment decisions (CHF

1566 ± 1840), particularly for second molars (CHF 2485 ± 2226). To compensate CBCT costs, 1.7

subjects were needed to treat to at least break even.

Conclusions: Data from CBCT facilitated a reduction in treatment costs and time for periodontally

involved maxillary molars in Switzerland. Based on these cost analyses, however, CBCT as

additional diagnostic measure is justified only when more invasive therapies are planned.

Increased implant failure rates have been

reported in the posterior maxilla, particularly

for implants with a minimally rough

(machined) surface placed in cancellous bone

(Jaffin & Berman 1991; Buhler 1994). In addi-

tion, bone augmentation procedures affecting

the maxillary sinus are frequently required as

staged approach due to an advanced alveolar

ridge resorption and/or an increased pneuma-

tization of the maxillary sinus. Possible risks

of these surgical interventions are greater in

patients with general medical diseases and/or

in smokers (Strietzel et al. 2007). However,

decision making in the posterior maxilla is a

complex scenario, involving functional, ana-

tomical and/or several tooth related aspects

(for review see Zitzmann et al. 2010a). Main-

taining a compromised maxillary molar

becomes an interesting conservative thera-

peutic option, in particular in periodontitis

patients (for review, see Walter et al. 2011).

Cone beam computed tomography (CBCT)

has been validated in vivo for the assessment

of furcation-involved maxillary molars. The

CBCT data were found to be accurate in

assessing the amount of periodontal tissue

loss and in classifying the degree of furcation

involvement (FI) in maxillary molars (Walter

et al. 2010). In addition, the three-dimen-

sional images revealed several findings such

as the surrounding bony support of each max-

illary molar root, fusion or proximity of

roots, periapical lesions and missing bony

walls (Walter et al. 2009). The clinical rele-

vance of these radiographic data was analysed

regarding the decision-making process for

resective or non-resective therapies. These

treatment options were classified according

Date:Accepted 25 August 2011

To cite this article:Walter C, Weiger R, Dietrich T, Lang NP, Zitzmann NU.Does 3-dimensional imaging offer a financial benefit fortreating maxillary molars with furcation involvement? – Apilot clinical case series.Clin. Oral Impl. Res. 23, 2012, 351–358doi: 10.1111/j.1600-0501.2011.02330.x

© 2011 John Wiley & Sons A/S 351

to their invasiveness ranging from minimal

invasive supportive periodontal treatment

(SPT) to maximal invasive extraction and

implant restoration. Significant discrepancies

between conventional and CBCT-based

treatment approaches were found in most

situations, which possibly necessitate intra-

surgical changes in the treatment plan in

those cases with no CBCT available (Walter

et al. 2009).

In general, a novel clinical tool has to be

validated both from the clinicians‘ and the

patients‘ perspective. Obviously, financial

restrictions may preclude advanced treatment

procedures in many periodontitis patients,

and attention should be given to patient-cen-

tred outcomes and financial aspects in clini-

cal trials to ensure appropriate allocation of

resources (Bragger 2005). Recently, economic

analyses of periodontal diagnostics and/or

treatment techniques have received increas-

ing attention (Higashi et al. 2002; Pretzl

et al. 2009; Listl & Faggion 2010; Listl et al.

2010), and it has become apparent that there

is a need for a critical appraisal of novel

instruments, techniques and procedures,

including CBCT, from a patients’ perspec-

tive.

The aim of this pilot project, including 22

molars with FI, was to analyse the potential

financial benefit and time saving of using

CBCT for the decision making in the poster-

ior maxillary region.

Material and methods

The study group comprised 12 patients, three

women and nine men, with an average age of

57.5 years (range: 41–80 years) and a diagno-

sis of generalized chronic periodontitis.

Patients were consecutively recruited during

September 2006 and May 2008 from the pool

of patients at the Department of Periodontol-

ogy, Endodontology and Cariology, Univer-

sity of Basel, Switzerland. The study was

approved by the Ethics Research Committee

of the University of Basel, Switzerland (EK:

279/09). Patients were thoroughly informed

about the rationale for the study and the

methods applied, and gave their informed

consent. A total of 11 first and 11 second

maxillary molars with 66 furcation entrances

were included.

The detailed clinical and radiographic peri-

odontal examinations were described previ-

ously (Walter et al. 2009). Relevant data are

shown in Table 1. In brief, complete clinical

and radiographic examinations were per-

formed by two trained periodontists (N.U.Z.

and C.W.). After patient’ instruction, case

presentation and initial treatment, non-surgi-

cal scaling and root planning was performed

at least 6 months prior to inclusion in the

study on all teeth with periodontal probing

depths of �4 mm. Patients with at least one

maxillary molar with persisting increased

probing pocket depth (PPD � 6 mm) and/or

advanced FI, defined as horizontal interradic-

ular loss of periodontal tissues of degree II or

III (Hamp et al. 1975), were considered for

inclusion in this investigation. The CBCTs

were performed in the posterior maxillary

area using the high resolution imaging sys-

tem 3D Accuitomo 60, XYZ Slice View To-

mograph (J. Morita, Kyoto, Japan) with

cylindrical volumes of 4 9 4 cm to

6 9 6 cm.

The software i-Dixel-3DX (J. Morita) with a

linear measurement tool and a digital magni-

fication lens was applied, which facilitates a

continuous motion with the cursor in the

three-dimensional area visualized in the

three planes on the computer screen. The

CBCT images of each tooth included were

analysed in the horizontal, sagittal and trans-

versal sections by two of the authors (C.W.

and N.U.Z.) with respect to factors relevant

for the decision-making process. FI was cal-

culated and characterized according to Hamp

et al. (1975). The surrounding bony support

of each maxillary molar root was assessed in

the appropriate sagittal or transversal plane

in the long axis of the root. In addition, the

residual tooth lengths including the root

compartment not surrounded by alveolar

bone and the clinical crown were measured

and presented as ratios between supported

and unsupported tooth lengths. In addition

radiographic findings obtained from CBCT

imaging were identified and categorized as

root fusion (A1–3), root proximity (B1–3),

periapical lesion (C1–3), combined periodon-

tal-endodontic lesion (D1–3), or other find-

ings, such as root perforation, fenestration

defects, missing buccal/palatal bone plate, or

overfill of the root canal (E). (For details, see

Table 1.)

Treatment recommendations

Clinical and radiographic findings with intra-

oral photographs were presented to a peri-

odontist not involved in the clinical therapy

(C.W. or N.U.Z.) without viewing the corre-

sponding CBCT images. The periodontists

then made recommendations for additional

periodontal therapy. The treatment proce-

dures were classified according to the gradua-

tion of invasiveness (GoI) from a less

invasive, i.e. keeping as much periodontal

attachment as possible, to a more invasive

approach (Walter et al. 2009; Table 2). For

example, surgical treatment of the first maxil-

lary molar applying an apically repositioned

flap was judged as less invasive compared

with root resection. If the clinical and radio-

graphic findings did not clearly indicate a spe-

cific periodontal therapy, several reasonable

more-or-less invasive treatment procedures

were considered (Table 1), and all analyses

were performed for the least (minimal) and

the most (maximal) invasive treatment proce-

dures. In a second step, CBCT data were

presented, and the periodontist treating the

patient (C.W. or N.U.Z.) and a blinded peri-

odontist (C.W. or N.U.Z.) discussed possible

treatment options for the affected tooth.

Based on clinical data, periapical radiographs

and CBCT findings, a consensus was finally

reached for the most adequate treatment

approach described as the CBCT-based treat-

ment procedure (Table 1; Walter et al. 2009).

Evaluation of treatment costs and in-officetime

In Switzerland, dental services are generally

paid for by the patients themselves. Excep-

tions to this principle are accidents, congeni-

tally missing teeth, or severe systemic

diseases such as oral cancer. The costs of den-

tal treatment are regulated according to the

tariff structure of the Swiss Dental Associa-

tion (contract and rate, Schweizerische Zah-

narzte-Gesellschaft, Swiss Society of

Odontology SSO). A specific dental treatment

or treatment sequence is assigned to a

specific number of tariff points, which in

turn, are multiplied by a factor in the range of

3.1–5.5, depending on the treatment time, the

difficulty of the therapy or the degree of spe-

cialization of the performing clinician. For

instance, a periodontal flap surgery (No. 4140)

is assigned 160 tariff points. With a multipli-

cation factor of 3.7 for an assistant professor

at the University of Basel, the fee is Swiss

Franc (CHF) 592, whereas any additional costs

for this procedure such as anaesthesia or

regenerative materials, are charged separately.

For the current investigation, treatment

costs for molar treatment were calculated on

an individual basis according to the official

Swiss tariff structure. Costs included peri-

odontal surgery, reconstructive treatment, as

well as laboratory fees (CHF 800 for a single

crown on a natural tooth, CHF 1600 for a

single crown on an implant) and implant

material (CHF 1000), if deemed necessary.

Costs for CBCT amounted to CHF 290.

All costs were expressed in Swiss Francs

(CHF 100 = Euro 81.778 on 7 June 2011,

352 | Clin. Oral Impl. Res. 23, 2012 / 351–358 © 2011 John Wiley & Sons A/S

Walter et al �Benefit of 3D imaging

Table

1.Clinicalandradiographic

data,treatm

entreco

mmendationsandcalculatedco

standtimedifferences

Subject

No.

Tooth

PPD

mb-

mp

FI(b/

mp/

dp)†

Supp-unsupp-

tooth

length-ratio

(mb/db/p)†

Additional

data

†,‡

CBCT-based

treatm

ent

reco

mmendation§

Minim

alinva

sive

treatm

ent

reco

mmendation§,¶

Treatm

ent

cost

reduction

(CHF)

**

Treatm

ent

time

reduction

(min)**

Maximalinva

sive

treatm

ent

reco

mmendation§,¶

Treatm

ent

cost

reduction

(CHF)

**

Treatm

enttime

reduction

(min)**

127

3/4/

6/5/

2/7

III/III/

III

3:16/3:16/4:15

B1

1b

1b

00

4b

�782.55

�117.5

226

3/3/

3/8/

5/6

III/III/

III

–/3:11/–

C2,D1,D3,

E5

1b

�399.60

�60

3a

�1400.45

�210

16

2/3/

4/6/

6/6

III/III/

III

5:12/2:14/4:13

–1b

1b

00

1b

00

17

5/4/

5/6/

2/7

III/III/

III

4:11/4:11/4:12

B1

1b

0�1

75.75

�26

5�4

463.85

�670.24

327

4/5/

8/8/

2/7

III/III/

III

5:15/5:15/7:13

A1

1b

1b

00

4b

�782.55

�117.5

416

3/2/

3/5/

2/2

III/III/

III

3:15/–/–

A3,D2,

D3,E

53b

�1400.45

�210.30

50

0

526

2/3/

9/8/

2/3

III/0/

III

7:13/2:15/5:13

–3a

3a

00

3a

00

27

6/2/

4/8/

4/5

0/I/II

8:15/3:14/7:15

B1

3a

1a

�399.60

�60

1a

�399.60

�60

626

4/3/

5/6/

2/3

I/0/I

*B1

1a

1a

00

4b

�782.55

�117.5

27

5/3/

6/6/

3/5

0/0/0

*B1

1a

1a

00

4b

�782.55

�117.5

727

2/2/

3/3/

2/3

III/III/

III

6:14/6:14/6:14

B1

1b

1b

00

4b

�782.55

�117.5

826

3/2/

9/11/

3/2

I/0/I

6:9/–/2:18

A3

1a

1a

00

3a

�1000.85

�150

27

7/2/

9/10/

6/7

III/III/

III

4:16/6:13/7:12

B1

1b

1a

00

5�4

463

�670.24

926

3/2/

6/5/

2;8

0/III/

III

7:13/7:13/6:15

A1

3b

1b

�399.60

�60

3b

00

27

5/2/

8/8/

3/5

0/III/

III

8:14/8:14/8:13

A1

3b

1b

�399.60

�60

3b

00

16

2/2/

7/8/

2/3

0/0/II

8:12/8:12/7:13

B1

1a

1b

00

4b

�782.55

�117.5

17

3/2/

4/4/

2/4

0/0/0

12:10/12:10/9:11

B1

01b

�811.25

�121.8

5�5

856

�829.27

© 2011 John Wiley & Sons A/S 353 | Clin. Oral Impl. Res. 23, 2012 / 351–358


Table

1.(continued)

Subject

No.

Tooth

PPD

mb-

mp

FI(b/

mp/

dp)†

Supp-unsupp-

tooth

length-ratio

(mb/db/p)†

Additional

data

†,‡

CBCT-based

treatm

ent

reco

mmendation§

Minim

alinva

sive

treatm

ent

reco

mmendation§,¶

Treatm

ent

cost

reduction

(CHF)

**

Treatm

ent

time

reduction

(min)**

Maximalinva

sive

treatm

ent

reco

mmendation§,¶

Treatm

ent

cost

reduction

(CHF)

**

Treatm

enttime

reduction

(min)**

10

16

4/5/

9/7/

6/5

III/III/

III

–/3:15/–

D1,D3

51b

�399.60

�60

4b

�1182.15

�177.5

17

7/3/

6/8/

3;9

III/III/

III

5:12/3:12/3:14

C1,C3

1b

3b

�1000.85

�150.3

5�4

463.85

�670.24

11

16

3/3/

5/6/

5/8

III/III/

III

6:13/4:16/7:15

D3

1b

1b

00

4b

�782.55

�117.5

12

26

4/6/

9/5/

9/8

III/III/

III

5:13/–/–

D2,D3

51b

�399.60

�60

4a

�1182.15

�177.5

27

3/2/

4/7/

6/3

I/I/I

3:19/5:18/2:19

B1

1a

1b

00

5�4

560.05

�684.69

Mean

values

(±SD

)

�263(384)

�40(58)

�1566(1840)

�233(271)

Medians

(IQR)

0(400)

0(60)

�783(851)

�118(128)

FI,furcationinvo

lvement;

PPD,probingpocketdepth.

*Su

pported-unsupportedtooth

length-ratiowasnotcalculateddueto

lack

ofradiographic

boneloss

alongtheroots.

†Findingsobtainedfrom

conebeam

computedtomography(CBCT)im

ages.

‡Additionalradiographic

data

were

categorize

dasfollows:

A:fusionofthewhole

orpart

oftw

oadjacentroots

indicatedbythelack

ofaseparatingperiodontalligament(A

1mesiobuccalanddistobuccal,A2mesiobuccalandpalatal,A3distobuccalandpala-

tal),B:rootproximityindicatedby2separatingperiodontalligaments

(B1mesiobuccalanddistobuccal,B2mesiobuccalandpalatal,B3distobuccalandpalatal),C:periapicallesion–localize

dradiolu-

cency

surrounding

the

apicalregion

(C1

mesiobuccal,

C2

distobuccal,

C3

palatal),D:co

mbined

periodontal-endodonticlesion

–radiolucency

around

the

apexco

mmunicating

with

the

periodontal

defect

(D1mesiobuccal,D2distobuccal,D3palatal),E:otherfindings,

such

asrootperforation,fenestrationdefects,

missingbuccal/palatalboneplate,orove

rfilloftherootcanal.

§Treatm

entreco

mmendationclassifiedaccordingto

thegraduationofinva

sive

ness

(fordetails,

seeTable

2).

¶Minim

alandmaximalinva

sive

treatm

entreco

mmendationobtainedfrom

clinicalandtw

o-dim

ensionalradiographic

findings.

**Calculatedtreatm

entco

st/tim

ereductiondueto

additionalCBCTim

aging.Theco

sts(CHF290)andtimespan(25min)foraCBCTwere

notincludedin

thecalculation.Exa

mple

subject

No.2:In

all3

inve

stigated

molars,FI

degreeIIIwasfound

forallfurcation

entrances.

The“Su

pported:unsupported

tooth

length-ratio”andthe“additionaldata”reve

aled

decisive

differences.

Attooth

No.26the

mesiobuccalandpalatalroots

were

notsupportedcircularlybybone,andadditionalfindings(C2,D1,D3,E)clearlyindicatedextractionofthis

tooth

astheappropriate

option.In

contrast

both

right

maxillary

molars

(No.16,17)were

maintainable

byan

apicallyrepositioned

flap

inco

njunction

with

atunnelpreparation

according

toCBCTdata

(FIand

additionalfindings).Theminim

allyinva

sive

treatm

entreco

mmendationbasedonclinicalandperiapicalfindingsfortooth

No.26wasapicallyrepositionedflapwithtunnelpreparation(G

oI1b),whereastheCBCT-basedtreatm

entreco

mmenda-

tionindicatedextraction(G

oI5).Fo

rthis

situation,theadditionalco

stsandtime,if

noCBCTis

ava

ilable,would

comprise

anexp

lorative

surgicalprocedure

withCHF399.60and60min.Themaximally

inva

sive

clinicallybased

treatm

entreco

mmendation

forthis

maxillary

molarwasamputation/trisection

ofthedistobuccalroot(G

oI3a),

and

root-canaltreatm

entofatleast

two

roots

with

threeroot

canals

would

have

been

perform

ed

priorto

periodontalsurgery.AsCBCTdata

indicated

extraction,thepreviousroot-canaltreatm

ent(CHF1000.85,150min)and

theexp

lorative

surgicalprocedure

(CHF399.60,60min)would

have

tobeco

nsideredasove

rtreatm

ententailingunnecessary

costs(CHF1400.45)andtime(210min).



http://finance.yahoo.com/currency-converter/).

In addition to the consideration of mere

costs, the length of the in-office treatment

time was calculated according to the tariff

points and costs per minute (i.e. nine tariff

points for 5 min treatment time). The time

needed for a CBCT was estimated to be

25 min. The costs and in-office time required

for periodontal treatment according to the

classification of invasiveness of an upper

molar are shown in Table 2.

Comparison of costs and time for conventionaland CBCT-based treatment planning

The CBCT-based treatment recommendation

was considered as the “appropriate” advice,

and it was assumed that a deviant clinically

based treatment plan had to be altered during

the surgical procedure. In fact, the periodon-

tal surgeries performed based on the CBCT-

planning did not require any changes intra-

surgically (Walter et al. 2010). If a treatment

plan based on the clinical and plain film diag-

nosis had to be altered according to intra-sur-

gical findings (in the absence of a CBCT),

these intra-surgical changes would have

increased or decreased the cost and required

additional in-office treatment time in some

cases. For instance, the treatment recommen-

dation based on clinical and periapical find-

ings for a given maxillary molar was

amputation/trisection of the palatal root (GoI

3b), and root-canal treatment of at least two

roots with three root canals performed prior

to periodontal surgery. If the CBCT-based

treatment recommendation indicated an open

flap debridement with apically repositioned

flap (GoI 1b), the previous root-canal treat-

ment would have to be considered as over-

treatment entailing unnecessary cost (CHF

710.85) and time (125.3 min). If the clinically

based therapeutic procedure was 1b, and the

CBCT-based treatment recommendation was

3b, reliance on clinical and plain film diagno-

sis would have resulted in an open flap proce-

dure that would have to be terminated to

perform root-canal treatment prior to root

amputation. For this situation, the additional

costs and time of an explorative surgical pro-

cedure were estimated as CHF 399.60 and

time as 60 min.

Statistical analysis

The treatment costs and the time needed

were calculated for both the minimal and the

maximal invasive treatment procedures based

on clinical and plain film radiography

(Table 2). The costs and time potentially

saved by preventing an inappropriate therapy

based on the clinical and plain film assess-

ment alone were also calculated. The mean

values and the standard deviations (± SD) of

the cost and time differences were calculated

for all treatment procedures as well as for the

group of minimal and maximal invasive

treatment proposals. This was also calculated

for the first and second molars separately.

Due to the non-normal distribution of these

differences, median values were calculated.

The corresponding 95% confidence intervals

Table 2. Estimation of financial costs and time efforts according to the graduation of invasiveness(GoI) based on the Swiss dental tariff structure

Graduation(GoI) Description

Costs (TP 93.7)(CHF)

Treatmenttime(min)

0 SPT 175.75 261a OFD with/without ARF (no tunnel preparation) 891.70 1341b OFD with/without ARF with tunnel preparation 987.90 1482 Root separation 3898.75 4653a Amputation/trisection of distobuccal root 3841.40 4563b Amputation/trisection of palatal root 3841.40 4563c Amputation/trisection of mesiobuccal root 3723 4384a Trisection and removal of palatal and distobuccal root 3693.40 4344b Trisection and removal of mesiobuccal and

distobuccal root3634.20 425

4c Trisection and removal of mesiobuccal and palatalroot

3634.20 425

5 Extraction, sinus floor elevation and implantrestoration

6031.75 515

SPT, supportive periodontal treatment; OFD, open flap debridement; ARF, apical repositioning flap.

(b)

(a)

Fig. 1. (a) Box-plots of calculated cost reductions (in CHF) from CBCT for maximal and minimal invasive treatment

options. (b) Number needed to treat to save treatment costs (in CHF) from CBCT-based therapy compared to clini-

cally based treatment recommendations.



of the medians and the two-sided P-value

were determined by bootstrap methods (Brad-

ley 1979), with the level of significance set at

a = 0.05. Minus signs indicate the cost or

time reduction, whereas zero values repre-

sent no benefits by the use of CBCT. As this

is a pilot clinical case series, analysing the

data from 22 teeth in 12 patients, the respec-

tive molars were considered to be indepen-

dent.

An empirical cumulative distribution func-

tion was applied to analyse the probability of

saving a distinct range of costs or time, and

to calculate the number needed to treat to

save a distinct amount of money or time. All

analyses were performed using the statistical

package R (The R Foundation for Statistical

Computing Version 2.9.2).

Results

Cost differences between the clinically basedand CBCT-based treatment recommendations

For the average number of minimal and

maximal invasive treatment procedures, the

use of CBCT resulted in a cost reduction of

CHF 915 ± 1470 on average (median: 400).

When the minimal invasive, clinically based

treatment procedure was considered alone,

the cost reduction amounted to CHF

�263 ± 384 (median: 0). With the maximal

invasive, clinically based treatment decision,

the costs were reduced by CHF �1566 ±

1840 (median: �783; Fig. 1a). Differences in

the cost reduction between the minimal and

maximal invasive treatments resulted in a

median of CHF �783 (95% CI: �892,783;

P < 0.001). There was no difference in the

cost reductions using CBCT for the minimal

invasive treatment options between the first

(CHF �273 ± 422) and second (CHF

�253 ± 361) molars (median of the difference

0; 95% CI: �400,400; P = 0.94). For the

maximal invasive treatment recommenda-

tions, the cost reduction was larger for the

second molars (CHF �2485 ± 2226) than for

the first molars (CHF �647 ± 547). The med-

ian of the difference was CHF �783 (95%

CI: �4463,0; P = 0.05).

The empirical cumulative distribution

function revealed that a cost reduction of at

least CHF 290, which corresponds to the

CBCT costs, was achieved in 59.1% of all

cases, 43.2% led to a cost reduction of CHF

� 600, 25% to CHF �900, and 11.4% to

CHF � 1500. This corresponds to 1.7 subjects

needed to treat to at least break even,

whereas the number of treatments needed to

save at least CHF 600, CHF 900 or CHF 1500

was 2.3, 4 and 8.8 respectively (Fig. 1b).

Time differences between the clinically basedand the CBCT-based treatmentrecommendations

The overall time differences for all cases

revealed a time reduction of �136 ± 217 min,

on average, due to the CBCT-based treatment

decision, with a median of �60 min. Time

reduction in the group of minimal invasive

clinically based treatments amounted to

�40 ± 58 min (median: 0). With the maximal

invasive clinically based treatment decision,

the time saved was �233 ± 271 min (median:

�118; Fig. 2a). The differences in time reduc-

tion between the minimal and maximal inva-

sive treatments resulted in a median of

�118 min (95% CI: �134,�118; P < 0.001).

As with the cost reductions, most time was

saved when treating second molars, but only

provided that the maximal invasive treat-

ment option was selected (�369 ± 327 min),

whereas with the first molars in this group

�97 ± 82 min were saved (median of the

difference �118; 95% CI: �558,0; P = 0.05).

Differences between the first and second

molars in the group of minimal invasive

treatments were small (�41 ± 63 and

�38 ± 54 min). The median of the difference

was 0 (95% CI: �60,60; P = 0.94).

Although each case benefited from a mini-

mum time saving of 26 min, at least in every

second case a time reduction of 60 min was

achieved and at least in every third case a

reduction of 122 min was achieved (Fig. 2b).

Discussion

The reasoning of the current cost analysis is

based on the treatment philosophy of pocket

elimination as the appropriate treatment

approach in maxillary molars with persisting

increased PPD and/or FI (Walter et al. 2011).

Data from this Swiss specific preliminary

study demonstrate that CBCT-based treat-

ment decisions for maxillary molars may lead

to an overall reduction in treatment costs

and time compared with the treatment deci-

sions resulting from clinical and plain film

diagnosis only. Although the cost and time

reductions were smaller for minimal invasive

clinically based treatment decisions and

(a)

(b)

Fig. 2. (a) Box-plots of time (in minutes) saved due to CBCT for maximal and minimal invasive treatment options.

(b) Number needed to treat to save treatment time (in minutes) from CBCT-based therapy compared to clinically

based treatment recommendations.



similar for the first and second molars, the

greatest differences were found among the

second molars in the group of maximal inva-

sive treatments. Overall, the costs and time

efforts for a CBCT were compensated for and

justified in about 60% of all cases, whereas a

more substantial financial benefit of CHF

600 or more was achieved in only 43% of

cases.

The CBCT has received considerable atten-

tion both in everyday dental practice, as indi-

cated by an increasing number of tomograms

in Switzerland, and in the scientific litera-

ture. In general, when novel clinical or diag-

nostic techniques or instruments are

introduced, their validation is required not

only from a professional perspective, but also

from an economic point of view (Bragger

2005). Two such studies focused on the intro-

duction of the controversial microbiological

and genetic testing in the field of periodon-

tology. Both tests were valued and frequently

applied by dental care providers in the 1990s

(Tanner 1992; Kornman et al. 1997), although

evidence of their clinical value for diagnosis

and treatment decision-making was lacking

(Mombelli et al. 2002; Loos et al. 2005). More

than 10 years later, it was demonstrated that

the routine use of neither microbiological nor

genetic testing had clinical advantages or eco-

nomic benefits (Bragger 2005; Huynh-Ba

et al. 2007). Validation of novel techniques or

instruments within a reasonable timeframe

is mandatory and should actually be per-

formed before introduction to the market.

Long-term data about the advantages of

CBCT images, including CBCT-based therapy

with periodontal surgery in maxillary molars,

are currently unavailable for large patient

samples. The present analysis of the poten-

tial time and cost benefits of CBCT in maxil-

lary molar treatment was performed on a

small patient sample in Switzerland, and

provides only preliminary evidence that

applying CBCT may be worthwhile in certain

situations from an economic perspective.

The CBCT has been validated clinically

and proven to be accurate in classifying the

degree of FI in maxillary molars in humans

(Walter et al. 2010). In addition, it also

appears to have a significant impact on the

decision-making process involved in treating

such teeth (Walter et al. 2009). The findings

from the current cost analyses indicated the

need for a critical appraisal of CBCT applica-

tions in upper molars. In most cases with

clinically based GoI � 1 (0: SPT, 1a/b: open

flap debridement), CBCT imaging seems to

have no, or only minor impact in economic

benefit and reducing treatment time only

slightly, if at all. With more invasive clini-

cally based treatment decisions (>degree 1 in

the GoI), however, the benefits of using

CBCT are greater, probably because the indi-

cation for tooth extraction is clarified. On

one hand, a straight forward tooth extraction

followed by implant placement and restora-

tions is feasible, thereby avoiding explorative

periodontal surgeries when the tooth is not

maintainable. On the other hand, unneces-

sary tooth extractions and implant placement

in sites where teeth would be maintainable

may be avoided. Moreover, root-canal treat-

ments in sites planned for GoI degree 2, 3 or

4 (separation, amputation or trisection) may

be prevented, when CBCT revealed morpho-

logical variations such as root proximities or

root fusions, which precluded the clinically

based resective treatment planning.

The financial benefits of using CBCT and/

or the savings in in-office time were more

pronounced in second maxillary molars than

in first molars. These differences were most

likely related to the different morphologies of

these teeth, i.e. the reduced degree of root

separation in second maxillary molars. This

is potentially associated with errors in furca-

tion diagnoses and inappropriate treatment

decisions. As a consequence, indications for

resective treatment of furcation-involved sec-

ond maxillary molars seem to be restricted.

Further limitations in this situation arise

from the difficulty in gaining adequate access

and of performing oral hygiene procedures in

the distal maxillary area even after periodon-

tal furcation surgery (Ak et al. 2005). Extract-

ing periodontally compromised second

maxillary molar is a treatment option, pro-

vided that the first molar is intact. Compre-

hensive treatment with CBCT imaging may

also be indicated for restorative reasons, par-

ticularly when deciding whether or not to

maintain an important abutment tooth and/

or to avoid augmenting the maxillary sinus

to facilitate implant placement (Zitzmann

et al. 2010b; Walter et al. 2011). In many

cases, there is no indication to replace a fur-

cation-involved second molar with a dental

implant, and the functional unit is not

replaced. This concept may be supported

from an economic point of view in accor-

dance with the present analyses.

Recently, cone beam CT technology has

received considerable public attention, and

the use of repeated CBCT scans in young

patients during orthodontic treatment (Silva

et al. 2008) was critically reviewed (Bogda-

nich & McGinty 2010). Controversial

impacts of CBCT manufacturers in promot-

ing the technology for several dental applica-

tions in the absence of sufficient evidence

were also discussed. The main goal of diag-

nostic radiology is to keep the radiation dose

“as low as reasonably achievable,” and this

should also be a prerequisite for adequate

CBCT application in dentistry, as increased

radiation in the dental office may potentially

cause malignancies, including thyroid cancer

or intracranial meningioma (Hallquist &

Nasman 2001; Longstreth et al. 2004; Hujoel

et al. 2006). The current cost analysis of

CBCT imaging in the treatment of furca-

tion-involved maxillary molars may provide

some guidance for the critical use of this

novel radiographic method. The potential

risks associated with additional radiation

exposure are only justified in single cases

and have to be evaluated in each individual

situation.

Acknowledgements: The authors are

grateful to U. Simmen and A. Schotzau

(Statisticians, Basel) for performing the

statistical analyses, and Silvia Dingwall for

proofreading the English manuscript.

Source of funding

The study was self-funded by the authors and

their institution.

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