a preliminary report of the cost-effectiveness of tooth replacement strategies for partially dentate...

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A preliminary report of the cost-effectiveness of toothreplacement strategies for partially dentate elders

Gerald McKenna1, P Finbarr Allen1, Noel Woods2, Denis O’Mahony3, Cristiane DaMata1,

Michael Cronin4 and Charles Normand5

1Restorative Dentistry, Cork University Dental School and Hospital, University College Cork, Ireland; 2Centre for Policy Studies, University

College Cork, Ireland; 3School of Medicine, University College Cork, Ireland; 4School of Mathematical Sciences, University College Cork,

Ireland; 5School of Health Policy and Management, Trinity College Dublin, Ireland

Gerodontology 2012; doi: 10.1111/j.1741-2358.2012.00665.x

A preliminary report of the cost-effectiveness of tooth replacement strategies for partially dentateelders

Objective: To compare the cost-effectiveness of conventional treatment using partial dentures with

functionally orientated treatment to replace missing teeth for partially dentate elders using a randomised

controlled clinical trial.

Background: In many countries, including the Republic of Ireland, the only publically funded treatment

option offered to partially dentate older patients is a removable partial denture. However, evidence suggests

that these removable prostheses are unpopular with patients and can potentially increase the risk of further

dental disease and subsequent tooth loss.

Materials and Methods: Fourty-four partially dentate patients aged 65 years and older were recruited.

Patients were randomly assigned to the two treatment arms of the study. The conventional treatment group

received removable partial dentures to replace all missing natural teeth. The functionally orientated group

was restored to a Shortened Dental Arch (SDA) of 10 occluding contacts using resin-bonded bridgework

(RBB). The costs associated with each treatment were recorded. Effectiveness was measured in terms of the

impact on oral health-related quality of life (OHRQoL) using OHIP-14.

Results: Both groups reported improvements in OHRQoL 1 month after completion of treatment. The

conventional treatment group required 8.3 clinic visits as compared to 4.4 visits for the functionally

orientated group. The mean total treatment time was 183 min 19 s for the conventional group vs. 124 min

8 s for the functionally orientated group. The average cost of treatment for the conventional group was

487.74 Euros compared to 356.20 Euros for the functional group.

Conclusions: Functionally orientated treatment was more cost-effective than conventional treatment in

terms of treatment effect and opportunity costs to the patients’ time.

Keywords: elderly, partially dentate, prosthodontics, cost-effectiveness, quality of life

Accepted 12 December 2011

Introduction

As the global population ages, an increasing num-

ber of older patients are retaining natural teeth into

old age1,2. Advances in preventative regimes as

well as changing attitudes have meant that older

patients are demanding treatment provision based

around retention of existing teeth rather than

extraction and replacement. A variety of options

exists to replace already missing teeth but many

partially dentate older patients are prescribed

removable partial dentures. In some countries with

publically funded dental care programmes, this is

often the recommended and proscribed treatment

of choice for partially dentate adults. Such pros-

theses have been shown to be unpopular with a

� 2012 The Gerodontology Society and John Wiley & Sons A/S 1

significant proportion of patients whilst potentially

contributing to an increased risk of dental disease3.

Alternative treatment options involve providing

patients with a functional dentition rather than

replacement of all missing natural teeth. The

shortened dental arch (SDA) concept is a well-

established, functional treatment planning philos-

ophy based around the idea of preservation of 10

occluding pairs of teeth without the need for a

removable prostheses4. The philosophy of the SDA

involves the direction of treatment efforts and re-

sources towards preservation of the anterior and

premolar teeth, which have been called the ‘stra-

tegic’ part of the dental arch5. The concept remains

controversial for some dentists, and examples of

criticism are that loss of molars is associated with

reduced masticatory performance and that a SDA

could cause functional overloading of the teeth

and temporomandibular joints6. However, other

authors have found no evidence of this, and the

literature indicates that the SDA can provide satis-

factory oral functionality and comfort4,7. The SDA

philosophy also fits within the World Health

Organisation’s8 suggested goal for oral health that

adults retain for life a healthy, functioning denti-

tion of at least twenty teeth and not require a

removable prosthesis to replace missing teeth.

Previous randomised controlled clinical trials

have compared removable partial dentures with

functionally orientated treatment options in groups

of older patients. These studies have shown that in

patients restored using removable dentures, caries

was observed more frequently compared to those

treated functionally using fixed bridgework9. Those

wearing removable partial dentures also required

more prosthodontic maintenance although overall

survival rates of the prostheses for the two groups

were comparable10. No previous randomised con-

trolled clinical trials have compared the cost-effec-

tiveness of delivering these two different tooth

replacement strategies.

Often decisions on treatment provision are made

without proper consideration of the economic im-

pact with a lack of information on the total costs

and outcomes of available treatment options mak-

ing treatment choices more difficult. Intelligent

clinical judgments should be made on the basis of

outcomes of alternative treatment modalities,

considering the cost to the patient. Various eco-

nomic models have been used in dentistry and

medicine and to evaluate various treatment

modalities. Cost-effectiveness analysis is one of the

economic models used to assess the monetary value

of a treatment. Cost-effectiveness analysis has been

shown to be a useful tool in many studies including

quantitatively comparing dental implants with

fixed bridges, experimental caries-control regi-

mens, large amalgams vs. crowns and various

periodontal treatment modalities11,12.

The purpose of this study was to compare the

outcomes of two different tooth replacement

strategies: conventional treatment using removable

partial dentures and functionally orientated treat-

ment based on the SDA concept. The study also

recorded the total costs involved in providing each

of the two different treatment alternatives.

Materials and Methods

Partially dentate patients aged 65 years and older

attending Cork University Dental Hospital seeking

dental treatment were invited to participate in the

research study. Patients were included if they had a

minimum of six sound remaining natural teeth in

one arch, no systemic medical conditions prevent-

ing routine dental treatment, no evidence of

dementia, were able to have dental treatment in a

dental chair and could communicate in English.

Patients were randomly allocated to one of two

treatment groups using a random number genera-

tor stratified for age and gender. Patient allocation

was performed by a member of staff not involved

directly in the research project.

Each patient received a detailed oral examination

with dental status recorded using the International

Caries Detection and Assessment System (ICDAS),

Basic Periodontal Examination (BPE), number of

occluding contacts, bleeding score and plaque

score. Prior to prosthodontic rehabilitation, all pa-

tients received routine dental care as required

including standardised oral hygiene instruction,

extraction of teeth with a hopeless prognosis,

periodontal treatment and restoration of caries. If

after routine dental care had been completed, pa-

tients no longer met the inclusion criteria, that is,

extraction of teeth resulted in <6 sound natural

teeth remaining, they were eliminated from the

study. Participants were each provided with an

information sheet detailing the proposed treatment

options and each provided written informed con-

sent. Full ethical approval was provided by the

Cork University Teaching Hospitals Ethical Ap-

proval Committee.

Patients assigned to Group 1 (Conventional

treatment) had all missing natural teeth replaced

using a Cobalt-Chromium removable partial den-

ture. These were constructed according to a stan-

dardised protocol where primary and secondary

impressions were taken of each patient. The metal

frameworks were designed by a single clinician

� 2012 The Gerodontology Society and John Wiley & Sons A/S

2 G. McKenna et al.

after surveying each patient’s study models. The

dentures were retained using clasps, no precision

attachments were used. Those assigned to Group 2

(Functionally orientated treatment) were restored

to 10 occluding tooth contacts using Resin-Bonded

Bridgework (RBB). RBB was provided using a

standardised protocol which included minimal

preparation of abutment teeth, adequate thickness

of retentive wings (minimum 0.7 mm), chairside

sandblasting of the bridgework and cementation

using a composite resin cement under rubber dam

(Panavia� F, Kuraray Co. Ltd, Kita-Ku, Osaka, Ja-

pan.) The bridges were designed with modified ridge

lap pontics and used a cantilever design where one

tooth was replaced and a fixed–fixed design where

two teeth were replaced. The only exception to this

rule was where patients presented with only re-

tained anterior teeth where a cantilever design was

used to replace all missing premolar units. In both

arms of the trial, the aim was to eliminate dental

pathology and render the patients dentally fit.

The primary outcome measure from the trial was

OHRQoL, which was measured using the short

form of the oral health impact profile (OHIP-14).

OHIP-14 was completed prior to commencement of

the treatment and 1 month after the treatment was

completed. Patients recorded only negative events

associated with their mouth, teeth or dentures

using the OHIP-14 to give a score ranging from 0

(minimum) to 56 (maximum). High scores indi-

cated poor OHRQoL with low scores indicating

good OHRQoL13. For each patient, the treatment

time was measured using a stopwatch during each

appointment and the overall treatment time was

calculated. Costs involved in each procedure,

including laboratory bills, were recorded using

patient billing accounts. An estimation of the la-

bour costs involved was made from the total

treatment time required for each treatment arm.

Sundries involved in the treatment provision were

recorded for both groups.

Results

In total, 44 patients completed the trial in Cork

University Dental Hospital. Eighty-six patients from

Cork University Dental Hospital were invited to

participate in the study. Sixteen patients did not

meet the inclusion criteria for the trial and were

excluded, whilst 26 did not complete the initial

operative phase of treatment (Fig. 1). The patient

pool consisted of 28 women and 16 men with an

average age of 68.2 years (range 65–82 years).

Twenty-one patients received conventional treat-

ment (Group 1) compared with 23 who received

functionally orientated treatment (Group 2). All

the members of the conventional treatment group

received their allocated treatment; however, two

patients from the functionally orientated group

refused their allocated treatment and received

conventional treatment instead. These patients

were analysed according to the intention to treat

principle (Fig. 1; Table 1).

Both groups reported improvements in oral

health-related quality of life after completion of

treatment. After prosthodontic rehabilitation, pre-

operative and post-operative OHIP-14 scores were

compared using a Student’s T-test. Data were

analysed using SPSS� (SPSS, IBM Corporation,

Armonk, NY, USA), and statistical significance was

determined at p £ 0.05. For the conventional

group, the mean OHIP-14 score decreased from

12.4 pre-operatively to 3.3 post-operatively

(p < 0.001). In the functionally orientated group,

the OHIP-14 score decreased from 11.4 to 1.8 fol-

lowing treatment (p < 0.001). There was not a

statistically significant difference in OHIP-14 scores

between the groups at baseline or 1 month post-

operatively. (Figs 2 and 3)

For each participant, the number of clinical

appointments and total treatment time were re-

corded. For the conventional treatment group,

each patient required an average of 8.3 clinical

visits to complete their prosthodontic treatment.

The total time taken to complete these visits was on

average 183 min 19 s. As part of these clinical

visits, each patient required a mean of 2.3

appointments after the removable denture was

fitted for post-operative follow-up and review. For

the functionally orientated group, 4.4 visits were

required to complete their prosthodontic care. The

mean total treatment time was 124 min 8 s

including 0.8 follow-up visits for post-operative

care. The conventional treatment group had an

average of 6.33 teeth replaced at a laboratory cost

of 330.14 Euros. The functionally orientated group

had an average of 2.64 teeth replaced at a labora-

tory cost of 238.81 Euros (Table 2).

Using the top of the salary scale for the com-

munity dental service in Ireland (85 185 Euros), a

clinician providing care would be paid 44.37 Euros

per hour for 240 8-h working days per year. Using

this calculation, the labour cost of providing clinical

care for an average conventional patient was

135.42 Euros compared with 91.67 Euros for

functionally orientated care. The cost of sundries

involved in treatment provision were broadly

comparable with 22.18 Euros for each conven-

tional patient and 25.72 Euros for each functional

patient (Table 3).


Cost-effectiveness of tooth replacement strategies 3

Discussion

Partially dentate older patients are often prescribed

removable partial dentures despite the fact that

alternative treatment strategies exist. Such alter-

natives include fixed prosthodontic options with

dental implants but these are expensive and viewed

with scepticism by many older patients14. Evidence

shows that many partial dentures constructed are

rarely worn, especially those in the lower arch

involving bilateral free end saddles. Some studies

have estimated that the rate of non-wearing of

removable partial dentures may be as high as

40%15. Rehabilitation using functionally orientated

strategies have been shown to be acceptable to

patients and simple to provide for clinicians16. The

SDA approach has been proven to provide

adequate chewing function without the need for a

removable denture. It has also been shown to

provide occlusal stability and an acceptable aesthetic

result which patients find easy to maintain17. This

study aimed to evaluate the cost-effectiveness of

tooth replacement based on conventional and

functionally orientated principles.

The two treatment groups were randomly

selected and were comparable in terms of gender

and age profile. Each patient completed OHIP-14

questionnaires prior to and after treatment was

complete. These questionnaires were distributed by

a member of staff not directly involved in treatment

Excluded

• Not meeting inclusion criteria (16)• Declined to participate (26)

Randomised (44)

stratified for:

• Age• Gender

Allocation

Assessed for eligibility

(n = 86)

Allocated to CONVENTIONAL TREATMENT (n = 21)

• Received allocated treatment (n = 21)• Did not receive allocated treatment

(n = 0)

Allocated to FUNCTIONAL TREATMENT (n = 23)

• Received allocated treatment (n = 21)• Did not receive allocated treatment

(n = 2)2 Patients declined functional treatment. Received conventional treatment

1 month post treatment

Lost to follow up (n = 0)

1 month post treatment

Lost to follow up (n = 0)

Analysed (n = 21)

Excluded from analysis (n = 0)

Analysed (n = 23)

Excluded from analysis (n = 0)

Follow-Up

Analysis

Enrollment

Figure 1 Patient flow diagram.


4 G. McKenna et al.

provision to reduce potential bias. However,

each group illustrated a statistically significant

improvement in oral health-related quality of life

after treatment was provided. Previous studies have

illustrated that replacement of missing teeth with

removable partial dentures has a positive impact on

oral health quality of life18. In addition, restoration

to a SDA using RBB has been proven to have a

positive impact on oral health quality of life19. In

this study, sample size calculations were based on

the premise that one treatment was no worse than

the other and so the numbers of patients involved

may not have been sufficient to distinguish a

difference between the two groups.

The results from the study clearly illustrate that

for the initial phase of treatment, the costs involved

in provision of functionally orientated group were

significantly lower. Each patient required fewer

clinical visits to complete treatment, and the time

0

2

4

6

8

10

12

14

16

18

20

Pre-treatment Post-treatment

OH

IP-1

4 sc

ore

Figure 2 Boxplot illustrating change in OHIP-14 scores

in the Conventional Treatment Group.

Table 1 Demographic profiles of trial participants.

Group 1 Group 2

Conventional

Treatment

Functionally

orientated

Treatment

Number of participants

(n = 44)

21 23

Gender

Female (%) 61.9 65.2

Male (%) 38.1 34.8

Age

Mean 67.3 68.8

Range 65–77 65–82

Mean Pre-operative

OHIP Score (SD)

12.4 (3.52) 11.4 (7.2)

Mean Post-operative

OHIP Score (SD)

3.3 (1.5) 1.8 (1.6)

0

5

10

15

20

25

30

35

40

Pre-treatment Post-treatment

OH

IP-1

4 sc

ore

Figure 3 Boxplot illustrating change in OHIP-14 scores

in the Functional Treatment Group.

Table 2 Clinical treatment time for Conventional and

Functional Treatment Groups.

Conventional

Group

Functional

Treatment

Group

Mean number of initial

clinical visits

8.3

(Range 6–9)

4.4

(Range 4–7)

Mean number of

follow-up appointments

2.3 0.8

Average total clinical

time (minutes)

183 124

Table 3 Average treatment costs per patient.

Conventional

Group

Functional

Treatment

Group

Laboratory Costs per

patient (Euros)

330.14 238.81

Estimated Labour Costs

per patient (Euros)

135.42 91.67

Costs of Sundries per

patient (Euros)

22.18 25.72

Estimated Total Cost

per patient (Euros)

487.74 356.20



spent in the dental chair was much less. As well as

fewer initial treatment visits the functionally ori-

entated treatment group required less follow-up

visits (0.8 visits) compared with the conventional

group (2.3 visits). Previous studies have illustrated

that functionally orientated treatment provision

using RBB requires much less maintenance than

partial dentures3. In this trial, conventional pa-

tients returned for a variety of reasons including

denture discomfort and occlusal adjustment. From

the functionally orientated group, only five pa-

tients required follow-up care for reasons including

occlusal adjustment and removal of excess luting

cement. In addition to less clinical time required,

the functionally orientated treatment group re-

quired less laboratory expenditure compared with

the conventional group. As a result of aiming to

restore only 10 occluding contacts, on average, the

functionally orientated group had less than half as

many teeth replaced compared with the conven-

tional patients.

When the cost-effectiveness of the two treatment

arms was compared, it was calculated that every

one Euro spent on conventional treatment im-

proved patients’ OHIP score by 0.02. For func-

tionally orientated treatment, every one Euro spent

improved patients’ OHIP score by 0.03. Therefore,

in terms of treatment effect, or improvement in

Oral Health-related Quality of Life, functionally

orientated treatment is more cost-effective. In

addition, as functionally orientated treatment re-

quires fewer clinical visits and less treatment time,

it has a comparative advantage in terms of oppor-

tunity cost to the patients’ time. This is in addition

to the advantages which fixed prosthodontics offer

compared to removable options including a re-

duced maintenance burden for the patient and

improved oral comfort20,21.

After 1 month of treatment, it is inappropriate to

discuss survival of the restorations placed. How-

ever, other studies suggest that a statistically sig-

nificant difference in survival rate should not be

expected between the two groups3,22. For the par-

ticipants in this study, we may see increased failure

rates of the RBB because of the fact that the enamel

substrate used in bonding may be less than ideal

because of previous restorations, loss of crown

height and physiological tooth wear. Follow-up of

both groups is required to monitor future treat-

ment, complications and maintenance costs so as to

assess the long-term impact of both types of resto-

ration on oral health-related quality of life. How-

ever, initial results would indicate that functionally

orientated treatment is a more cost-effective alter-

native than traditional treatment using removable

partial dentures.

Conclusions

Restoration to a SDA using functionally orientated

treatment resulted in a similar improvement in

OHRQoL with fewer clinic visits, less operative time

and at a lower laboratory cost compared with

conventional treatment. Cost-effectiveness ratios

indicate that functionally orientated treatment is

more cost-effective in terms of treatment effect and

opportunity costs to the patient. Long-term follow-

up of both treatment groups is required to deter-

mine whether these initial findings continue over

the lifetime of the restorations.

Acknowledgements

This study was supported by a grant from the

Health Research Board of Ireland (HRB/2008/220).

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Correspondence to:

Dr Gerald McKenna, Clinical Fellow in Restorative

Dentistry/HRB Scholar in Health Services Research,

Restorative Dentistry, Cork University Dental

School and Hospital, University College Cork,

Ireland.

Tel.: +353 021 420 5033

Fax: +353 021 490 1193

E-mail: [email protected]



a preliminary report of the cost-effectiveness of tooth replacement strategies for partially dentate...

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