vermeulen et al 1996, frameprotheses overleving
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7/27/2019 Vermeulen Et Al 1996, Frameprotheses Overleving
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Ten-year evaluation of removable partial dentures: Survival
rates based on retreatment, not wearing and replacement
A. H. B. M. Vermeulen, DDS, PhD,” H. M. A. M. Kelt jens, DDS, PhD,”
M. A. van% Hof, PhD,b and A. F. Kayser, DDS, PhD”Trikon, Institute for Dental Clinical Research, School of Dentistry, University of
Ni jmegen, Ni jmegen, The Nether lands
From a group of 1480 patients, 1036 were treated with metal frame removable
partial dentures (RPDs) at least 5 years before this analysis. Of those, 7 48
patients who wore 886 RPDs were followed up between 5 and 10 years; 288
patients dropped out. The 748 patients in the study groups were wearing 703
conventionally designed metal frame RPDs and 183 RPDs with attachments.
When dropout patients and patients who remained in the study were com-
pared, no differences were shown in the variables analyzed, which indicated
that the dropouts did not bias the results. Survival rates of the RPDs were
calculated by different failure criteria. Taking abutmen t retreatment as
failure criterion, 40% of the conventional RPDs survived 5 years and more
than 20% survived 10 years. In RPDs with attachments crowning abutments
seemed to retard abu tment retreatment. Fracture of the metal frame was
found in 10% to 20% of the RPDs after 5 years and in 27% to 44% after 10 years.
Extension base RPDs needed more adjustments of the denture base than did
tooth-supported base RPDs. Taking replacement or not wearing the RPD as
failure criteria, the survival rate was 75% after 5 years and 50% after 10 years
(half-life time). The treatment approach in this study was characterized by asimple design of the RPD and regular surveillance of the patient in a recall
system. (J &-osthet Dent 1996;76:267-72.)
I n many countries a major part of the populat ion
has a n incomplete but stil l functiona l dentition. A sub-
stantial number of these edentulous port ions of the den-
tal arch are not prosthetically restored,l and many pa-
t ients are functioning with a shortened dental arch with-
out any need for treatment.2 Nevertheless, restoring oral
function and appearance is often necessary; there is a
particularly higher percentage of replacem ents in higher
economic gr0ups.l
Treatment options to replace missing teeth are ei ther
f ixed or removable appl iances; each has i ts own indica-
t ion.3 The f i rst reports about removable part ial dentures
(RPDs) indicated that these restorations could deter io-
rate the health of remaining dentition and surrounding
oral t issues.4,5 Few part ial dentures survived for more
than 5 to 6 years.6 Other studies demonstrated more fa-
vorable resul ts wi th respect to treatment with RPDs and
suggested that the negative effects could be counteracted
by a careful ly planned prosthetic treatment and regular
recal l appointments that included patient instruction,
retreatments of teeth, and prosthetic adjustments.7-g
Studies of the fol low-up of a large number of RPD s
over an extended per iod are scarce. This art ic le presents
the results of a lo-year longitudinal stud y of patients (n
“Assistant Professor, Department of Oral Function and Pros-
thetic Dentistry.
bAssociate Professor, Department of Statistical Consultation.
cProfessor, Department of Oral Function and Prosthetic Den-
tistry.
SEPTEMBER 1996
= 748) treated with RPD s and includes ‘703 conventional
metal f rame RPDs and 183 RPDs w i th at tachments . By
extrapolating survival curves, the eff icacy o f the treat-
ment and the need for retreatment could be determined.
MATERIAL AND METHODS
Participants
The patients for this histor ic study were recruited from
the cl inic of the Dental School in Ni jmegen, The Nether-
lands. The total sam ple co nsisted of 1480 patients, 68%
ofwhom were wome n. The mean age was 38 years (range
19 to 72 years). Fi fty- f ive patients were treated with an
acryl ic resin RPD only and were excluded from the study.
To ensure a reasonable fol low-up t ime, only those pa-
t ients who star ted their treatme nt at least 5 years be-
fore this analysis were selected, resul ting in an exclu-
sion of 389 patients. The remaining patients (n = 1036)
were treated with a metal frame RPD that could be of a
conventional design or provided with attachme nts. The
RPD s were subdivided into extension base and tooth-
supported base categor ies.All patients participated in a mainte nance program
and returned for follow-up at g-mon th intervals. Patients
who did not return for follow-up regularly (288) were
considered “ lost to fol low-up,” and data of these patients
were om itted when they did not return for at least 2
years. The data of the patients were col lected by stu-
dents and checked by staff mem bers. The data col lection
procedure was explained to the students.
THE JOURNAL OF PROSTHETIC DENTIST RY 26 7
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THE JOURNAL OF PROSTHETIC DENTISTRY VERMEULE N ET AL
Table I. Survival (% + SD) after 5 and 10 years for conventional RPD s (n = 703) according to di fferent fai lure reasons
(read from survival curves)
Maxilla Mandib le
Failure reason Extension base Tooth-supported base Extension base Tooth-supported base
Initial No. 78
Abutme nt retreatment (yr)
5 38 + 6
10 23 IL 8
Adjustmen t denture base (yr)
5 60 + 6
10 40 + 9
RPD fracture (yr)
5 84 + 5
10 65 f 9
168 338 119
41+ 4 38 f 3 38 zt 5
22 + 5 26 f 4 16 + 5
82 + 3 65 ZL 3 75 f 4
55 + 6 41 f 4 55 f 7
89 f 3 86 + 2 82 + 4
73 f 5 72 + 4 56 + 7
Table II . Survival (% + SD) after 5 and 10 years for RPD s with attachme nts (n = 183) divided into di fferent fai lure
reasons (read from survival curves)
Max i l la Mandib le
Failure reason Extension base Tooth-supported base Extension base Tooth-supported base
Original No. 21 20 83 59
Abutme nt retreatment (yr)
5 76 + 10 75 + 11 68 zi 6 592 7
10 48 ir 17 41+ 18 45 * 9 30 + 10
Adjustmen t denture base (yr)
5 72+11 83+ 9 29 + 5 89+ 4
10 36 + 17 66 f 17 10 + 5 65 k 10
RPD fracture (yr)
5 84 + 9 88+ 8 80 f 5 842 5
10 - 59 f 18 64 + 8 63 zk 10
Criteria of evaluation
At the star t of the study the distribution of the re-
maining denti t ion and the dental heal th was scored with
the fol lowing standard method s:
ment of fai lure. This treatment could be a new restora-
t ion or extraction. For si tuations that required extrac-
t ion, i t could be necessary to adapt the RPD to the new
environment.
1. caries determina tion with a mirror, explorer, and ra-
diographs,
2. pocket measuremen t with a pocket probe (Wil l iams,
Hu Fr iedy, Chicago) lO
3. determination of tooth mobi l ity wi th a 4-point scale,i i
an d
Corrections of the RPD i tsel f could have occurred dur-
ing the evaluation per iod. This retreatment consisted of
repairing, relining, rebasing, or recons truction of the
R PD .
4. measureme nt of the alveolar bone height on radio-graphs.
The f i rst retreatment caused b y fracture of the appl i-
ance or resorption of the alveolar ridge resulting in ad-
justment of the denture base marked the mom ent of fai l-ure.
The denti t ions were categor ized according to the
Kennedy Classi f ication. I2 Dur ing the recal l v isits the
changes tha t occurred to the teeth, the restorations, and
the RPD s were recorded. Moreover, al l retreatment of
the RPD s and treatments of the abutment teeth were
recorded. To study the survival rates of RPD s, three rea-
sons for fai lure were dist inguished: (1) treatment of the
abutment teeth, (2) corrections of the RPD , and (3) re-
placement of or not wear ing the RPD. For the survival
analysis on the basis of abutment treatment, the f i rst
treatment of one of the abutment teeth marked the mo-
For these failure reaso ns, 5- and lo-year survival rates
were read from the Kaplan-Meier survival curves (Tables
I and II) .
Som e of the earlier mentione d failure reasons 1 and 2
resul ted in restorative treatment of the abutment teeth
or corrections of the RPD s. However, these RP Ds were
functioning again after the adjustments had been per-
formed without any problems. Therefore Kaplan-Meier
survival curves were calculated, reflecting the percent-
age of RPD s that were replaced completely or not worn
anymore (Fig. 1). In si tuations that require replacement
26 8 VOLUME 76 NUMBER 3
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VERMEULEN ET AL THE JOURNAL OF PROSTHETIC DENTIST RY
CONVENTIONAL RPD’s
mandible
---j-- extension base - -@- -II=338
tooth-supportedn=119
10 0 -~--__
00
60
50
base
3. -‘-L-i- I0 12 3 4 5 6 7 a 0 lo
YEARS
RPD’s w ith ATTACHM ENTS RPD’s w i th ATTACHMENTS
mandible maxilla
L0 - L----L ___..-l _-___-'J.---L-.. J0 12 3 4 5 6 7 6 9 10
YEARS
CONVENTIONAL RPDs
maxilla
+ extension basen=78
loo r--T--
-9 - tooth-sup ported basen=168
L i40 ..L----L--I---L.-L--I L---l----0 12 3 4 5 6 7 6 9 10
YEARS
+ extension basen=21
100 "
so -
60 -
- -o- - tooth-supp orted basen=ZCt
30
2n -
,o -L---L-A-1-1 _---- ;-,y
0 12 3 d 5 0 IO
YEARS
Fig. 1. Survival curves o f RPD s on basis of replacement and not wear ing RPD .
or not wear ing the RPD , only the fai lure reason wa s
scored. Other fai lure reasons could occur simultaneously.
RESULTS
Dropout
Dropout
Because 288 patients dropped out and might bias the
resul ts of the study, the study group and the dropout
group were compared on the basis of seven var iables:
age, sex, number and type of remaining teeth, num ber
of abutment teeth, type of prosthesis, dental visi ts, andtreatment satisfaction.
First, a questionnaire was mailed to all dropout pa-
t ients. Those who did not respond were cal led by tele-
phone and requested to answer the questionnaire.
The dropouts and study group were matched with re-
spect to the mom ent of intake in the study, age, sex, and
type of prosthesis received. It was only possible to per-
form this for the dropouts between 25 and 65 years old.
Final ly, 593 patients of the study group and 248 drop-
outs remained in the dropout analysis.
A three-way analysis of var iance (dropout, sex, and
age) was appl ied to the seven mentioned var iables.
Of the 288 dropout patients, 149 (53%) responded to
the questionn aire, 129 (45%) did not respond , and 10
(3%) had died. Table II I summ arizes the reasons for the
dropout. The mos t important reason for not returning
for the recall ap pointments was “no t ime”; “moving out
of the region” was another frequent reason. An indica-
t ion for the dental awareness of the dropout group wa sthe fact that 80% of the responding dropouts were sti ll
visiting a den tist regularly.
The patient’s judgment with respect to the resul t and
the procedures of the treatment was included in the ques-
t ionnaire. Of the dropouts, 88% were satisf ied with the
resul t and 96% with the procedure of the treatment. For
5% of the patients dissatisfaction was the pr imary rea-
son for dropout (Table II I) . Seven percent of the drop-
outs did not wear the RP D in the maxi lla and 13% in the
mandible. In this aspect no di fference was found com -
pared to patients remaining in the study group.
The dropout groups and study groups were evaluated
SEPTEMBER 1936 26 9
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THE JOURNAL OF PROSTHETIC DENTISTRY VERMEULEN ET AL
Table III. Overview of reasons for dropout (a = 149)
Reason for dropout
No t ime
Moved
Prefer another dentist
Noncompl iance
Recal l procedure unknown
Dissatisf ied with treatment
No reason
%
34
29
12
10
5
5
5
with respect to classi f ication and type of prosthesis (Table
IV). Analysis of the classi f ication showed that for the
mand ible the nonresponding dropout group contained
significan tly more patien ts with a natural dentition (p =
0.04). Moreover, for the maxi l la signi f icantly more pa-
t ients were included in the study group who were classi-
f ied as Kennedy I and II (JI = 0.04) (Table IV). Analysis
of the type of prosthesis demonstrated that in al l drop-
out groups more patients with a complete denture were
included (p = 0.03) (Table IV). As shown in Table V, the
clinical variables for the different groups w ere similar
and did not reveal a significant difference betwee n
groups.
The dropout analysis showed that no ser ious activi ty
occurred as a resul t of dropout.
Survival rates of RPDs
In total , 886 RPD s worn by 748 patients were ana-
lyzed: 703 conventional metal frame RPD s (Table I) and
183 with attachme nts (Table II) . The distribution per
jaw and the di fferentiat ion into extension base and tooth-
supported base is also given. Mos t of the RPD s were in-
serted in the mandible; especial ly conventional exten-
sion-base RPD s consti tuted the larger part of the total
number of RPDs.
The number and survival percentages of the RPD s
after 5 and 10 years are shown in Tables I and II. By
use of the f i rst retreatment of one of the abutment teeth
as the criterion for failure, approx imately 40% of the
conventional RPD s survived 5 years and over 20% sur-
vived 10 years (Table I) . Between mandible and max-
i lla or extension-base and tooth-supported base RPD s,
only sl ight di fferences were noticed. For RPD s with at-tachme nts “abutment retreatment” resul ted in 59% to
76% survival after 5 years and 30% to 48% after 10
years.
Treatments related to adjustments of the denture base,
such as rel ining, rebasing, or reconstruction, were combined
as one cause of fai lure. A higher percentage of extension-
base RPD s needed an adjustment ofthe denture base within
a shorter t ime than did tooth-supported base RPD s. This
phenomenon was found especial ly in extension-base RPD s
with attachmen ts in the mandible (Table II) .
Another factor of fai lure was fracture of the RPD . The
percentage of extension-base RPD s with attachme nts in
the maxi l la after 10 years is not presented because of
the low number at r isk at that m ome nt. The percentage
of RPD s that presented no fracture within 5 years was
80% to 90%; after 10 years the percentages of RPD s with
no fracture var ied between 56% and 73%.
The di fferences within the groups of conventionalRPD s and within the groups of RPD s with attachm ents
were limited. Figure 1 il lustrates the Kaplan-Meier sur-
vival curves over 10 years for the di fferent RPD s. These
curves demonstrated that after 10 years about 50% of
al l RPDs were sti l l functioning.
Extension-base conventional RPD s tended to show
lower survival percentages than did tooth-supported base
RPD s. For RPD s with attachm ents in the mandible the
survival curves of the extension-base RPD s were less
favorable than those with tooth-supported bases. The
reason “no t wearing” accou nted for 5% of the failures in
RPD s with attachm ents, whereas in conventional RPD s
these percentages were 8% for the mandible and 4% for
the maxi l la.
DISCUSSION
This longitudinal study was conducted on 748 patients
with 886 RPD s examined dur ing a 5- to lo-year span.
In the ear lier studies car ies activi ty was reported to be
This research was not a controlled clinical trial and there-
high in patients with RPDs .4J3 This study does not support
fore some aspects should be interpreted careful ly. In
part icular , when cast restorations were needed on abut-
these negative effects. The resul ts of this study are in agree-
men ts, the choice between a conventional ly designed
RPD with only crowned abutmen ts or an RPD with at-
tachme nts was part ial ly dependent on the interest and
ment with those o f Bergman et a1.,7 who did not f ind a
exper ience of the staff membe r and the student. Another
phenomenon observed was also the high retreatment
marked increase in car ies caused by wear ing RPD s. In the
need of extension-base RPD s with attachm ents, leading
to a decrease of these restorations in later groups. For
current study and the study of Bergman et al . patients were
these reasons, i t is not appropr iate to compare the re-
kept under survei llance in an active recal l system , which
sul ts of RPD s with and without attachm ents.
was probably responsible for the low caries increase . A re-cent study by Drake and BeckI demonstrated the impor-
tance of patient educa tion, good oral self-care, and regular
professional recall for people who wear RPDs.
In 40% and 20% of the jaws with conventional RPD s
no restorative retreatment of any of the abutment teeth
was performed after 5 and 10 years, respectively.
Bergman et a1.7 reported 44% of the abutment teeth in
need of restorative treatment after 10 years. These per-
centages give the impression that in this study the re-
sul ts were more unfavorable. I t should be considered,
however, that the f i rst restorative treatment of one of
the abutment teeth w as taken as a cr i ter ion for fai Iure
27 0 VOLUME 76 NUMBER 3
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VEFlMEULEN ET AL THE JOURNAL OF PROSTHETIC DENTIST RY
Table IV. Distribution of stud y group (n = 593) and dropout group (n = 248) according to classification and type of
prosthe sis in max illa and mandible (in percenta ges)
Max i l la Mandib le
Study
group
Dropout group Study Dropout group
group
R N-R R N-R
Edentulous area
Complete
Kennedy I and II
Kennedy III
Kennedy IV
Natural dentition
Type of prosthesis
Complete denture
Free-end
Non free-end
No denture
28 32 25 -
36 26 26 62
28 32 32 31
3 5 7 3
5 5 10 4
28 37 35 1 8 16
19 13 10 54 54 40
28 28 27 24 18 22
25 22 27 20 18 22
69 51
27 36
1 0
3 13
I?, Respond ing dropout group; N-R, nonresponding dropout group.
Table V. Cl inical var iables of study and dropout groups (mean values)
Study group
(n = 593)
Dropout group
SD, total group
N-R
R (n = 139) (n = 109)
Total No. of teeth 16.5 16.1
No. of sound teeth 6.2 6.3
No. of abutment teeth 4.6 4.6
Bone height” 92.5 91.0
Mobility 0.17 0.12
R, Responding dropout group; N-R, nonresponding dropout group.
“Bone height expressed as a percentage of the maximum height of two thirds root length.
17.9 4.5
7.2 3.0
4.2 1.0
94.3 8
0.21 0.10
and that most RPD s had several abutm ents, leading to
a higher fai lure r isk per RPD . Moreover, many abut-
me nts were fi l led with plastic fi l l ing mate rials and only
one third were crown ed, which resulted in a large por-
t ion of abutment teeth at r isk for retreatment.
RPD s with attachments included a var ied col lection
of designs. M ost extension-base RPD s were provided with
Dolder bars and bal l or Dalbo a ttachme nts, whereas in the
non-free end ones primarily Dolder bars were used.15-17 The
survival curves, wi th the f i rst restorative treatment of an
abutment tooth as a cr i ter ion for fai lure, indicated that
cast crowns gave a retardation of decay as reported in ear-
l ier studies.8J3 The resul ts seemed to be comparable with
those of other studies18Jg when the values in this study are
reduced to two abutments per jaw.
As may be expected, extension-base RPD s, especial ly
in the mand ible, needed a higher percentage of adjust-
ments of the denture base. This can be explained by the
progression of the resorption in the edentulous parts of
the jaw, which was probably intensif ied by the pressure
of the free-end denture base. Bergman et al7 also re-
ported a great number of denture base adjustments af-
SEPTEMBER 1096 27 1
ter 10 years in a population that ha d a large nu mber of
extension-base RPDs.
Many of the extension-base RPD s were provided with
bal l attachm ents, which m ay be responsible for the un-
favorable resul ts of the RPD s with attachments. Dur ing
the f i rst years of the study the bal l attachme nts were
not provided with occlusal rests, resul ting in excessive
pressure on the alveolar bone and as a consequence a
high resorption rate, responsible for the high numb er of
adjustments needed. This problem could be prevented i fthe bal l attachme nts were suppl ied with vert ical occlusal
stops.=
Fracture of the RPD w as found in 17% after 5 years,
increasing to 35% after 10 years. A study of Korber et
a1.20 showed a repair percentage of 40% after 5 years, of
which 15% was exclusively caused by fracture of metal-
l ic parts. Spiekermanr?l reported a clasp fracture per-
centage of 19% after 4 .5 years. In fact, the fracture per-
centages of RPD s can be considered low consider ing the
high number of casting defects and inaccuracies men-
tioned in several studies.22,23
When replacement and not wear ing of the RPD were
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THE JOURNAL OF PROSTHETIC DENTIST RY VERMEULEN ET AL
combined as a cr i ter ion for fai lure, about 50% of the RPDs
survived 10 years. This f inding is in contrast wi th the
resul ts of Wetherel l and Smales,‘ j who reported that only
few prostheses lasted for more than 5 to 6 years.
Wetherel l and Smale@ and Roberts5 reported a large
number of RPD s that were not worn. Because of a prob-lem-oriented approach used in this stud y, a higher per-
centage of RPD s were worn by the patientsz4 The re-
sul ts of this study are confi rmed by Cowan et a1.,25 who
reported a high number of patien ts wearing their RPD
several years after insertion without apparent problems.
CONCLUSIONS
Within the l imits of this study i t was concluded that
the survival rate for conventional metal frame RPD s, on
the basis of replacement and not wear ing, is approxi-
mately 75% after 5 years and 50% after 10 years ( the so-
cal led hal f l ifet ime). The negative effect of an RPD on
the remaining teeth can be kept to a minimum .
With a simple RPD design and a regular survei llance
of the patient in a recall system with an individual ly
adjusted interval, the resul ts of RPD treatment wi l l en-
sure predictability.
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Reprint requests to:
DR. H. M . KELTJENS
UNIVER SITY OF NIJMEGEN
SCHOOL OF DENTISTRY
PHILIPS VAN LEY~ENLAAN 25
6525 EX NIJMEGEN
THE NETHERLANDS
Copyr ight0 1996 by The Editorial Counci l of The Journal of
Prosthetic Dentistry.
0022-391 3/96/$5.00 + 0. 10/l/74422
27 2 VOLUME 76 NUMBER 3
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