1
MINISTRY OF EDUCATION AND TRAINING MINISTRY OF HEALTH
NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY
*
TA QUOC DAI

ASSESS EFFICIENCY OF DENTAL PLATE CONTROL IN
PREVENTION OF DECAY TEETH AND GINGIVITIS IN
12-YEAR-OLD PUPILS AT SOME SCHOOLS IN THE
SUBURBS OF HANOI Major: Epidemiology
Code: 62 72 70 01


The thesis will be presented in the Institute – level Board of
Thesis Evaluation at National Institute of Hygiene and
Epodemiology

At … o’clock, day …… month ……. Year 2012

The thesis can be found at:
1. National library
2. Library of National Institute of Hygiene and
Epodemiology

3
ABBREVIATION
CPITN Community Periodental index of treatment needs
CI-S Calculus index simplified
II Intervention index
EI Efficiency index
ODC Oral and Dental care
IV Intervention
DI-S Debris index simplified
F Fluor
KAP Knowledge, Attitude, Practice
DP Dental plaque
SD School of dentistry
OR Odds Radio
OS Othodonto - Stomatology
OD Oral and Dental

network did not satisfy the requirements. Therefore, at the present, the oral
and dental prevention was the key mission of the Othodonto –
Stomatology major.
In Hanoi, the investigation results on the oral and dental health in 2007-
2008 with the pupils of primary and secondary schools showed that the
rate of oral and dental diseases were increased under the ages.
To strengthen the school of dentistry program, as well as find out the
new methods linking with the school of dentistry program aiming at
raising the quality, effectiveness of oral and dental diseases prevention for
the pupils, within the framework of the project “Assess the efficiency of
school of dentistry activities in Hanoi in 2009-2010 of National Institute of
Othodonto – Stomatology”, we researched the theme: “Assess the
efficiency of dental plaque control in decay teeth, gingivitis prevention
for the 12 years- old pupils at some schools in the suburb of Hanoi” to:

5
1. Describe the reality, some factors relating to the decay teeth,
gingivitis, dental plaque and knowledge, attitude, practice about the
oral and dental care for the 12 years-old pupils at some secondary
schools in Gia Lam, Quoc Oai District, Hanoi City in 2009.
2. Assess the efficiency of dental plaque control in the decay teeth,
gingivitis prevention for the 12-year-old pupils at 04 secondary
schools of two researched districts.

NEW CONTRIBUTIONS OF THE THESIS
1. The thesis provided the valuable reference information for the
specialized scientists about the oral and dental diseases, the oral and dental
care knowledge, attitude, practice and the reality of oral and dental care at
some secondary schools in the suburb of Hanoi.
2. The research result presented the effective intervention model to control

and dental diseases treatment, recovered the chewing function and
aesthetic, so that it was very costly. Today, thanks to the remarkable
progress of the science technology, it was found that the reason and
pathogenesis of the dental diseases were caused by the dental plaque, and
then the preventive methods were very effective. In some countries, the
decay teeth, gingivitis was significantly reduced. Therefore, WHO
recommended that all the countries worldwide should prevent the oral and
dental diseases early at the age of pupil, which was the most feasible
strategy.
Vietnam was the developing country, in the recent years, the
socioeconomic situation has been developed, the nutrition had many
changes such as using much sugar, milk, etc, whereas the community was
not aware enough about the risks, evils as well as the preventive measures
for the oral and dental diseases. Many research works showed that in many
local areas, the oral and dental diseases tended to be increased, while the
operation of the oral and dental disease preventive network did not satisfy
the requirements. Therefore, at the present, the work of preventing the oral
and dental diseases was the key mission of the othodonto – stomatology
major.
To solve this situation, in many previous years, the othodonto –
stomatology major actively performed the mission of initial oral and dental
health care, of which the key mission was the school of dentistry work
with 04 contents: Educate dentistry for the pupils, use the gargle with 0,2%
flour weekly in the school, fill the teeth slot, examine and treat early the
oral and dental diseases in the school. However, the implementation and
effectiveness of this work were different under each group of ages, each
period. Partly, the reason was that the knowledge, attitude and practice of
the pupils on the oral and dental care were various under each period, each
place; so that the rate of oral and dental diseases for the pupils was still
high. The intervention researches showed that if the preventive measures

important exotic agent in the oral and dental diseases. The dental plaque
could make the damages because of the two impact mechanisms: Direct
impact: Enamel made dental plaque become weak, disintegrate cell, peel
of many gummy tissues leading to gingivitis, prostaglandine destroyed
alveolar bone. Indirect impact: caused by bacteria and secretion of bacteria
as a antigen. These antigens stimulus the immune reactions ion site as well
as the whole body. Then, the intermediary products of the immune
reactions destroy the organization of gums. The capacity making the decay
teeth of the dental plate was based on its adhesion into the teeth, the
capacity making acid from C
12
and C
6
and pH of oral environment.
Methods to control the dental plaque: Mechanic methods: brushing
teeth, cleaning spaces between teeth, sprinkling method. Chemical
method: Use gargle for preventing and reducing the dental plaque with
flour to reduce the decay teeth, etc. Overcome and repair the errors:
Position of teeth, adjacent joints, repair the wrong teeth function.
Nutrition regime and preventive propaganda.

Chapter 2

8
SUBJECT AND RESEARCH METHOD

2.1. Subject, place and time of research
2.1.1. Research subject
- 12 years-old pupils, regardless of gender, were willing to join in the
research, excluding the pupils who change the school.

Z
2
1 - /2
[(1 – p1)/ p1 + ( 1- p2)/ p2] p
1
: 80%
n
1
= n
2
= p2: 40%
[ln (1 - )]
2

: 15%,
According to the formula: n
1
= n
2
=259 (Real research of 02 groups:609)
* Sampling method
Among 6 secondary schools, we chose 04 schools and contigently
distributed into 2 groups, the intervention group with 2 schools, 306
puplis: Dong Quang- Quoc Oai District (156 pupils) and Trau Quy Town-
Gia Lam District (150 pupils), the comparison group with 02 schools, 303

9
pupils: Quoc Oai Town- Quoc Oai District (152 pupils) and Da Ton- Gia
Lam District (151 pupils).
2.3. Research contents:

p
1 + p
1
: Rate before intervention
+ p
2
: Rate after intervention
Used intervention index (II) (rate %) to assess the intervention effect
between the intervention group and the comparison group:
Intervention index (%) = Efficiency index (intervention group) –
Efficiency index (comparison group)
Compared the result of the collected indexes before and after intervention
and give the essential conclusions.
Chapter 3
RESEARCH RESULTS 10

3.1. Reality of decay teeth, gingivitis, dental plaque, knowledge,
attitude, practice about oral and dental care and some factors related
to oral and dental diseases for the pupils
3.1.1. Reality of decay teeth, gingivitis and dental plate for the pupils
3.1.1.1. Reality of decay teeth

57.8 318

62.1 613

60.0
Gingivitis (CPITN = 1;2) 215

42.2* 194

37.9** 409

40.0
- CPITN =1 86 8.4 71 7.0 157

15.4
- CPITN =2 129 12.6 123 12.0 252

24.6
p
* - **
<0.05 (Quoc Oai and Gia Lam)
- Rate of gingivitis (CPITN=1.2) of the 12 years-old pupils in both two
districts was medium 40.0%.
3.1.1.3. Dental plaque reality of the pupils
Table 3.5. PI debris index reality of the pupils under district
Place

PI
≤ 2



Level 1

Level 2

Level 3
Qt % Qt % Qt % Qt %
Quoc Oai
(n=510)
25 4.9 41 8.0 401 78.6 43 8.5
Gia Lam (n=512) 24 4.7 38 7.4 392 76,6 58 11.3
Total (n=1022)
49

4.8

79

7.7

793

77.6

101

9.9

p>0.05


51

4.9


2

= 64.80 ; p <0.05
- The Calculus rate for the pupils in two districts was at the different
levels, ranked: Level 0, Level 1, Level 2, Level 3. The difference between
the rates of dental debris reality did not mean statistic (p >0.05).
3.1.2. Knowledge, attitude and practice about ODC of research pupils
3.1.2.1. Knowledge of Oral and Dental care
Table 3.15. the average mark of ODC knowledge of district’s pupils

Districts
Knowledge mark

Excellent

Good

Average

Amount

% Amount

% Amount



Amount

%

It was needed to brush teeth after the main meals each day:
Agreed 389 38.1
Teeth must be examined periodically
Agreed 251 24.6
It was needed to visit doctor during tooth’s pain
Agreed 408 39.9
Used toothpaste to brush was a prevention method of DC
Agreed 429 42.0
- Pupils who agreed to brush their teeth, used toothpaste to brush and visit
doctor during teeth’s pain every day account 38.1%, 39.9% and 24.6%
respectively, the remaining percentage of pupils did not agree or did not
know
3.1.2.3. Practice about ODC
Table 3.18. Practice about ODC daily (n = 1022)
ODC Amount

Scale (%)
Method of oral and dental hygienve after the main meal

Brushed teeth

230 22.5
Number of teeth -brushing per day:

Many times

beverage and beverages (n=1022)
Index

Amount

Scale (%)

Number of time of eating, drinking sweet food and beverage and
beverages each day:
- Many times

703 68.8
Oral and dental hygience after eating, drinking sweet food and beverage
and beverages
- Brushed their tooth

42 4.1
- 68.8% of pupils ate and drunk sweet food and beverage and beverages
(biscuit, sweet, cream, pepsi, etc.) many times per day. Only 4.1% of them
followed to brush their teeth after eating and drinking.
Table 3.24. To take a latest visit to dentist for teeth examination
(n=1022)
Index (time)

Amount

Scale (%)

- From 6 to 12 months 204 20.0
- Only 20% Pupils followed to visit doctor for periodical teeth

- There was a close relationship between oral and dental hygiene and
Permanent DT with OR=2.8; P<0.05
Table 3.28. Relationship between ODH and Gingivitis
ODC
Gingivitis
OR; p
Yes
No
Amount

(%) Amount

(%)
Not good 291 28.5 282 27.6 OR = 2,9

14

Good 118 11.5 331 32.4 p < 0.05
Total

409

40.0

613

60.0

After

(4)
PI ≤ 2
QT 113 265 112 102 p
1-2
<0.01

p
2-4
<0.01

134.5
125.6
% 36.9 87.7 36.7 34.0
PI > 2
QT 193 37 191 198 p
1-2
<0.01

p
2-4
<0.01

80.8
77.1
% 63.1 12.3 63.3 66.0
- PI ≤ 2 after IV of IV group increased clearly in comparison with pre-IV
(EI =134,5%, p<0.01). In the comparison group, PI ≤ 2 decreased (II =
125,6%).

-
4
<0.01

857.1
885.7
%

4.6 44.4 5.0 3.7
Level 1
QT 24 168 23 16
p
1-2
<0.01

p
2
-
4
<0.01

600.0
630.4
% 7.8 55.6 7.6 5.3
Level 2
QT 237 0 235 211

100.0
110.2
% 77.5 0 77.6 70.3

Before

(3)
After

(4)
Level 0

QT 58 63 57 41
p
1-2
>0.05
p
2-4
<0.05
8.6
36.7
%

19.0 20.9 18.8 13.7
Level 1
QT
172 176 171 177
p
1-2
>0.05
p
2-4
>0.05
2.3

After IV of IV group, Level 0 increased clearly in comparison with pre-
intervention (EI=8.6%, p>0.05) and in the comparison group, level 0
decreased II=36.7%).
After IV, Level 1 increased clearly in comparison with pre-intervention
(EI=2.3%), and in the comparison group, level 1 lightly increased (II=
1.2%).
3.2.1.2. Preventive efficiency of DT

Diagram 3.4. Permanent DT scale in two groups of pupils
Remark:
IV group: before intervention, 95 (31.0%) pupils out of (306 pupils) got
DT, after intervention, 95% pupils out of (302 pupils) got DT (31.5%).
Comparison group: before IV, 94 pupils (31.0%) out of (303 pupils) got
DT, after 12 months 118 pupils (39.3%) out of 300 pupils got DT.
After IV, DT scale in the IV group was lower than that of the comparison
group with the meaning of statistics (p<0.05)

16

3.2.1.3. Preventive efficiency of gingivitis
Table 3.35. Number of pupils gets gingivitis

O
IV group
Comparison
group

p
EI
IV Group

(CPITN = 1;2)

QT

123 63 121 138 p
1-2
<0.05

p
2-4
<0.01

48.8
62.8
% 40.2 20.9 39.9 46.0
- O scale after IV of IV group clearly increased in comparison with pre-IV
(EI=48.8%), meanwhile,O scale in the comparison group increased
( II=62.8%).
3.2.2. Efficiency for KAP about ODC of pupils
3.2.2.1. Efficiency for knowledge about ODC of pupils
Table 3.38. The average mark about ODC knowledge of two pupil groups
Mark of
knowledge
IV group

Comparison
group

p


2
-
4
<0.05
117.7
74.0
% 20.3

44.7

21.1

30.7

Average

QT 189 42 183 151 p
1-2
<0.01
p
2-4
<0.05
77.8
60.3
% 61.8

13.9

60.4


Before

(1)
After
(2)
Before

(3)
After

(4)
II (%)

Daily teeth brush after the main mealAgreed

QT
116 250
118 145 p
1-2
<0.01
p
2-4
<0.05

115.5
92.6
%

24.1

26.7

Used toothpaste to brush was preventive method of oral and dental desease
Agreed
QT
128 272
127 151 p
1-2
<0.01
p
2-4
<0.05

112.5
93.6
%

41.8

90.1

41.9

50.3

- Agreement attitude of pupils about daily tooth brush after the main meal
clearly increased in comparison with pre-IV (EI=115.5%, p<0.01) and II in
the comparison group was 92.6% after IV of IV group.

II (%)
Before
(1)
After
(2)
Before
(3)
After

(4)
Method of oral and dental hygiene after the main meal:
Brush QT 67 228 64 70 p
1
-
2
<0.01 240.3

18

teeth % 21.9

75.5

21.1

23.3

p
2
-

Table 3.42. Time to brush and change teeth of two groups of pupils
Index
IV groupComparison
group

p

EI
IV Group

II (%)
Before
(1)
After
(2)
Before
(3)
After

(4)
Time to brush teeth each time
More than 3
minutes
QT 93 226 92 122 p
1-2
<0.01
p

Table 3.43. Eat, drink sweet food and beverage and the ODC after eating, drinking
sweet food and beverage and beverage of two groups of pupils
Index
IV Group Comparison
Group

p

EI
IV Group

II (%)
Before

(1)
After

(2)
Before

(3)
After

(4)
The number of times of eating, drinking types of sweet food and beverage/
day:
QT 211 116 209 180 p

-
4
<0.05

940.0
916.9
% 4.9 51.7 4.3 5.3
- The rate of pupils who ate, drunk sweet food and beverage many
times/day after the IV of IV Group significantly reduced in comparison
with the before-IV rate (EI = 45.0%, p < 0.01). After IV, the rate of IV
Group’s the pupils who ate, drunk types of sweet food and beverage many
times/daysharply reduced in comparison with that of the Comparison
Group (II = 58.9%).
- The rate of pupils who brushed the teeth after eating, drinking types of
sweet food and beverage after IV of IV Group significantly increased in
comparison with the before-IV rate (EI= 940.0%, p < 0.01). After IV, the
rate of IV Group’s pupils who brushed the teeth after eating, drinking
types of sweet food and beverage significantly increased in comparison
with that of the Comparison Group (II= 916.9%).
Table 3.44. Examine and treat teeth in the latest time of two groups of pupils
Index
(Time)
IV Group

Comparison
Group

p

EI


215.5
199.7
% 19.0

60.6

18.8

22.0

- The rate of pupils who went to the dentist for dental examination in the
latest time, from 6 – 12 months after IV of IV Group significantly
increased in comparison with the before-IV rate (EC = 215.5%, p < 0.01).
After IV, the IV Group’s rate of pupils who went to the dentist for dental
examination in the latest time, from 6 -12 months significantly increased in
comparison with that of Comparison Group (II = 199.7%).

Chapter 4
DISCUSSION
4.1. The reality of the DT, G, DP, KAP on ODC and some factors
related to OD diseases of the pupils.
4.1.1. The pupils’s reality of the DT, G, DP
4.1.1.1. The Decay teeth’s reality

20

The result of research showed that the PDT rate of the group of pupils
in general research in two districts was low, at 31.1%, which was
represented in Table 3.1. Of which, the PDT rate of Quoc Oai District’s

4.1.1.3. The dental plaque’s reality of the pupils
According to the WHO’s rank: PI ≤ 2: ODH was good; PI > 2: ODH was
not good; Such as, the pupils whose ODH was not good account for
63.0%, while the studetns whose ODH was good accounted for 37.0%. In
the period of new establishment, DP was the colorless thin film, therfore,
through the clinical way, it was hard to discover it by normal oral and
dental examination methods. To identify the reality of DP and ODH of the

21

pupils, we had to conduct the method of dental plate dyeing by eosin 2%.
By this way, the students’ bad ODH reality was appreciated according to
the PI and it was higher than that was appreciated according to the OHI-S.
4.1.2. The pupils’KAP on ODC
4.1.2.1. The pupils’knowdges on ODC:
According to research result in Table 3.15, the pupils in 2 districts
had the rate of knowledge marks on ODC at different levels, ranking in the
high-low order. Average: 61.3%, Credit: 20.5%, Good: 18.2%, the
difference on the knowledge mark level was meaningful in statistics
(p<0.05),.
4.1.2.2. The attitude on ODC of the pupils
In the Table 3.17, it was shown that only 38.1% children agreed to
brush teeth after the main meal. Such as, they had not clearly understood
the benefits of brushing teeth in ensuring the oral and dental health,
therefore, they had improper attitude on this issue.
4.1.2.3. Practising on ODC of the pupils
Regarding on the teeth brushing practice after meal, currently, just
22.5% brushed teeth by the toothbrush after main meal. The result in Table
3.17 showed that there was 38.1% pupils who agreed to brush teeth after
the main meal. This showed that there was huge gap between attitude and

reduces; therefore, the intervention was very effective with II= 885.7%.
Such as, the students’ index of residue sticking to teeth was significantly
improved while in the comparison group , after 12 months, the index of the
residue sticking to teeth increased every day appropriately with the age,
which proved the intervention was very effective.
Tran Thu Thuy and the base of instructing the pupils to brush teeth within
2 months showed that the DI-S reduces in comparison with the
Comparison Group , which had the meaning of statistics (p<0.05).
The dental plaque index in Table 3.31 showed: The rate of level 0
after IV of IV Group increased in comparison with the before-IV rate with
EI = 8.6%, p > 0.05. After 12 months, the rate of level 0 in the Comparison
Group reduced, therefore, the intervention was effective with II = 36.7%.
Such as, the dental plaque index of the pupils under the IV Group
was partly improved while the dental plaque situation of the Comparison
Group after 12 months increased according to the age; therefore, the
intervention was effective.
According to Chibinski AC, PochapskiMT. et al, applying the
chemical method (mouthwash) for the children from 7-12 years old; the
result showed that the DP and G bleeding reduced. The authors Ersin NK,
Eden E. et al utilised the chemical methods for the children from 11- 13
years old and the result showed that DP was reduced and ODC was
controlled. Our research result was similar to the research results of two
above authors.
4.2.1.2. Evaluate the efficiency of DT prevention
The result of the Table 3.4 showed the efficiency of DP control by
the mechanic and chemical methods for the DT: In the IV Group, DT rate
did not increase but in Comparison Group, the DT rate increased from
31.0% to 39.3%. After the intervention, the DT rate in the IV group was
lower than that in the Comparison Group, which brought the meaning of
statistics (p < 0.05). Such as, after one year of DP control, in the IV Group,

4.2.1.3. Evaluate the efficiency of the gingivitis prevention
After IV: The gingivitis rate of IV Group significantly reduced while
this rate increased in the Comparison Group. This showed that the
intervention with II = 62,8% was very effective. After the intervention, the
gingivitis-bleeding rate of IV Group ended while this rate of Comparison
Group increased by 19.0%. The method of intervention was very effective
with II= 121.3%.
Comparing the result of DP index with the result of evaluating the
situation of oral and dental disease at the equivalent groups, it was shown
that there was the close connection between DP situation and oral and
dental diseases. In the intervention of DP index, the gingivitis rate was also
high. After the intervention, the DP situation was controlled significantly
and the DT was controlled with no increase. The DP control made

24

important contributions to reduce the DT and gingivitis diseases of the
pupils.
The author Trinh Dinh Hai used the method of dentistry education, clinical
prevention (take the enamel, provisional coating, etc), within 8 years, the
gingivitis rate reduced by 50.0%. The result of our research applied for 12
year-old pupils in one year with the method of DP control showed that the
gingivitis reduced by 20.0%, the DP reduced (because some pupils had the
enamel at the level: 2; 3; therefore, it was needed to take the enamel, the
gingivitis would end) and then the DT was controlled.
4.2.2. Evaluate the efficiency for the pupils’KAP on the ODC
4.2.2.1. Evaluate the efficiency for the pupils’ knowledge on ODC
Through the students’ knowledge intervention, IV Group on ODC
significantly increased in comparison with the pupils at the same age of the
control group, it was stated that the intervention was very effective (The

with ≥ 3 healthy hexadecimal areas at the acceptable level from 59.2% to
83.0%. In addition, the intervention increased the PI ≤ 2 and reduced the
indexes: DI-S, CI-S, ODH index and changed the rule of natural progress
according to these’s indexes. The result of DP control in the group of
pupils was intervened, which contributed to explain the obtained results in
reducing the oral and dental diseases of the pupils in the group of
intervention and then affirmed that DP control was obviously effective in
preventing the DT and gingivitis

CONSCLUSION
1. The reality of DT, G and DP; knowledge, attitude, practice on the
ODC and some factors related to the pupils’ oral and dental disease.
- The reality of DT, Gingivitis: The common rate of permanent DT of
12 year-old pupils in two districts was low, at: 31.1% (Quoc Oai: 38.4%,
Gia Lam: 23.8%; p <0.05). The DMFT index of 12 year old pupils in two
districts was low, at: 0.93 (Quoc Oai: 1.10, Gia Lam: 0.76). The common
gingivitis rate of 12 year old pupils was at the average level: 40.01%
(Quoc Oai: 42.2%, Gia Lam: 37.9%; p <0.05).
- The DP’s reality:
PI: PI ≤ 2, accounted for 37.0%; PI >2 accounted for 67.0%.
The index DI-S: Good: 12.5%, Not good: 87.5%. The index CI-S: Good:
75.4%, Not good: 24.6%.
The rate of pupils whose ODH was not good: H56.1% (Quoc Oai: 61.4%,
Gia Lam: 50.8%;p<0.05). Good: 43.9% (Quoc Oai: 38.6%, Gia Lam:
49.2%).
- The pupils’ KAP on the ODC: The credit and good knowledge
capacity was low; the average knowledge: 61.3%. The proper attitude
accounted for low rate: 38.1% on agreeing to daily brush after main meal.
Practice: The rate of pupils who brush teeth after main meal was low,
22.5%; there was only 4.1% pupils who brush teeth after eating the sweet