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INNOVATION EFFECT ON THE MODEL FOR DENTAL DISEASES
Tosiro Shimada, Meiji University, Tokyo, Japan
Hirokazu Mizushima, Japan Dental Association, Tokyo, Japan
Takahiro Kojima, Senshu University,Kanagawa Prefecture, Japan
Koichiro Okumura, Japan Dental Association, Tokyo,Japan
Abstract
We gave areport on the model for dental diseases at the 1987
System Dynamics Conference.
The model consists of 4 sectors: demography, cavities, pyorrhea and
baby teeth. The demographic sector covered populations of 5 three
-year age groups under 14 years of age and 13 five-year age groups
above 15 years of age. The cavities sector and pyorrhea sector were
composed of populations of five-year age groups, on the other hand,
the baby teeth sector used populations of three - year age groups.
From the total number of defective teeth, total dental costs
in Japan were calculated annually from 1963 and projected to 2025.
We added to this model a new level variable which is technology
(rate variables and multipliers) in order to demonstrate to the effect
of technology on the other level variables.
‘New simulation results will be reported at the International System
1, MODEL FOR DENTAL DISEASES
1,1 Parts composing the model
This model consists of 5 sectors: demography, dental caries,
pyorthea, baby teeth, and technology. In each sector we deal with all
of Japan. Relations among sectors are shown in Fig.1.
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Relation among Sectors
Pig.1
The demographic sector covers populations of 5 three-year age
classes under 14 years of age and 13 five-year age classes above 15
years of age. ‘The former are the classes 0-2, 3-5, 6-8, 9-11 and 12-14
years of age, and the latter are the classes Of 15-19, 20-24, oo»
70-74 and 75- years of age. The population of each age class depends
on the rates of birth and death. The first age class Z0 begins with
births and end where a new age class begins or, through deaths within
the age class. Our other age classes Z3, Z6,..... Z75 follow this same
1, 2 Demographic Sector
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The flow diagram of this sector is shown in Fig.2.
5 Year Age Classes
i
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i =
Death Rate Death Rate oa rie Death Rate
— i
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Fig.2 Flow Diagram for Demographic Sector
3 Year Age Classes
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1. 3 Dental Caries Sector
The Dental Caries Sector has 13 subsectors corresponding to
13 five-year classes of the population sector.
Dental caries are classified as follows:
Healthy teeth ; Carious symptoms and dental care are not recognized,
CO : Similar to healthy teeth, but there is no agreement as to’ whether
teeth are decayed or not.
Cl : Small surface cavities which may be easily filled and treated.
C2: Cavities are worse than in Cl, but health teeth may be
restored by fillings being done without pulpectomy.
C3 : Cavities are worse than in C2, after pulpectomy. In some cases
decayed teeth are only filled, but generally metal crowns may
be used, In the case of front teeth complete care of bridges may
be necessary.
C4 : Carious symptoms are serious enough that decayed teeth must be
extracted and a denture may be necessary.
The number of C1 teeth is first computed. Then C2,C3,C4, filled
successively computed as seen in Fig.3.
Data for this sector have all been collected by the Japan
Dental Association.
Fig.3 Relation among Diseases
1. 4 Pyorthea Sector
1. 4.1 The Patient Population for C1,C2 and C3.
The patient population for C1,C2, and C3 is obtained from the sum
of C1 C2 and C3 teeth for five-year age classes divided by the number
of C1,C2,and C3 teeth per patient.
1.4.2 The Periodontal Patient Population for Each Age Class
This variable may be calculated from the sum of the above
population of periodontal patients of each age class times the cost of
treatment per capita.
1.5 Baby teeth sector
1.5.1 Number of Defective Baby Teeth
The number of defective baby teeth for a three-year age class
is obtained from the population of the class times 20 teeth per capita
times the rate of defects or disease .
1, 5.2 Cost of Baby Teeth Treatment
‘This variable may be computed from the total sum of the number of
treated baby teeth for each defect or disease and for each age class
times the cost per tooth,
2. Orthodontic Treatment
First the patient population for orthodontic treatment is
obtained from the sum of the population of each age class times the
Tate of patients for orthodontic treatment, The total cost in Japan for
orthodontic treatment can be calculated from the above population for
orthodontic treatment multiplied by the cost per patient.
3. Dental Cost
Total dental costs in Japan (CHIHI) are obtained as follows:
CHIHI = total demand * unit cost
total demand (hours)
unit cost (¥1,000 / hour / dentist)
Unit cost per dentist per hour is obtained from the model of
a Japanese Dental Office.
For the base model the ratio of treatment cases incurred to
the total was 0.94 and constant.
4. The Effect of Technology on Dental Costs
‘We made inquiries about the effect of technology on dental care.
With reference to various expectations the technology growth rate
is assumed as follows:
1993 2003 2013 = 2023
10% 20% 30% 40%
4.1 The Effect of Transfer Rate Changes
4.1.1 CO -> Cl Transfer Rate Change
We assume the effect of technology on CO -> Cl transfer change as a
table function of technology as shown in Fig.4.
that the total dental cost in
2025 should decrease by about
18% compared with the base model.
It is probable that the
quality of dental care will
improved considerably.
t
GG decreasing
Transfer Rate
ty te
ia iis ia
" Technology
FPig.4 Co- Ci Transfer Rate
4.1.2 Decrease in Periodontal Patient Population
A decrease in the number of Decreasing, t
/ ; Pericdoacel
periodontal patients was assumed Patients If
as shown in Fig.5. The simulation
result shows that the total dental
cost decreases by 20% compared
with the base model.
i er ss a
, Technology
Fig 5 Periodontal Patients
42 The Effects of Technology on the Variables of the Dental Office Model
42.1. The Effect of Increase of the Number of Cases
Dental cost treated in the model of dental diseases equals the total
demand multiplied by unit cost. This data was obtained from the model
for a Japanese dental office.
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In the dental office model the number of cases is one of main
variables. It is defined to be the number of patients and new patients
multiplied by the average number of cases per patient, We assume the
effect of technology innovation on the number of cases, as shown
in Fig.6.
The simulation result shows
that in 2025 both the unit
cost and the total dental cost
increase to 81% compared with
the base model. Thus technology
may increase the unit cost and
the total dental cost considerably.
4.22 Change of Average Paints
Increasing
Number
of Cases
Tz is 14
~ Technology
Fig.6 Number of Cases
‘We assume the change of average
points up to 15% as shown in Fig.7.
The simulation result shoWS yo seasing t
that in. 2025 both of the unit Average 12
cost and the total dental Points
cost increase 17.2% compared LL pmnmnnnornrornmnrnn eves
with the base model. i
a
™ Technology
Fig.7 Average Points
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43 Change of Treating Hours of Dentures
Dental materials must improve in terms of quality and treatment hours
for dentures may increase. 7PGattag™= t
‘Thus we assume the increase Hours of 1.5}-s-orco-weororoornvoey
rate up to 50% as shown in Dentures |
Fig.8. The simulation result
shows that in 2025 the total
dental cost increases by 23.2%
compared with the base model.
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Al. 120130 14
44 Mixed Change > Technology
Fig.8 Treating Hours of
44.1 10% Increase in Averaged Points and Dentures
40% Increase in the Number of Cases
The simulation result shows that the unit cost and the total dental
cost both increase to 94.8% compared with the base model. This increme
nt equals roughly the sum of 81% of the increase in the number of cases
and 10% of the increase in average points.
44.2 40% Increase in the Number of Cases and
50% Increase in Treatment Hours of Dentures
The simulation result shows a 123% increase’ in the total dental
cost in 2025 compared with the base model. This percentage is
a little larger than 104.2%, that is, the sum of 81% increase in
the case of 40% increase in the number of cases and 23.2% increase
in the case of 50% increase in treatment hours of dentures.
This may mean, the unit cost increase with regards to the rising
number of cases accelerates the total dental cost growth by the
increasing hours for treatment of dentures.
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5. CONCLUSION
we have attempted to formulate a System dynamics model for dental
diseases which have four sectors of demography, dental caries, pyorrhea
and baby teeth. We also added a new level variable ( technology ),
rate Variables and multipliers to express the effect of technology
on the other level variables. Technology innovation will affect the
CO0->C1 transfer rate, periodental patient population, the number of
cases and the average point and treatment hours of dentures.
These simulation results were explained.
This study is a research project of the Japan Dental Association.
REFERENCES
1. Hirsch, Gary B. and W.R.Killingsworth," A new Framework for
Projection Dental Manpower Requirements ", Pugh-Roberts Associates
Inc., pp 1-63 ,1973.
2. Shimada Toshiro and K. Fukushima," A system Dynamics Model of Japanese
Dental Office ", Proceedings of the International Conference on
Cybemetics and Society, pp 538-543, 1980,
3, Shimada Toshiro, Kenji Fukusima, Kinya Machida and Akira Uchino, " A.
Simulation Model ford Dental Diseases", Proceedings of the
1987° International Conference of the System Dynamics Society, pp.
476-481, 1987.
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