In our study, as in the others performed, a lack of knowledge in this area was noted (1,5). The behaviour of dentists and prosthesis technicians that this study highlights is probably due to the lack of information from the guidelines recommended by regulatory associations such as CDC and ADA. Dental impressions disinfection by immersion with 3% hydrogen peroxide, MD520® (Durr™), or sodium hypochlorite at 1% and 5.25% (and after tap water rinse) does not negatively impact the three-dimensional shape of the impressions. It will be necessary to invest in training at pre- and post-graduate levels in order to update the knowledge of health professionals, so they can recognize the importance of these prevention methods, accept them as crucial, to demystify the fear of dimensional changes after disinfection procedures and avoid the consequences of double disinfection.
Azevedo, Maria João (1,2); Correia, Inês(1); Azevedo, Álvaro(1); Sampaio-Maia, Benedita(1,2)
;Portela, Ana(1)
(1) Faculdade Medicina Dentária Universidade do Porto (FMDUP)
(2) INEB – Instituto Nacional de Engenharia Biomédica; i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
Among dentists, 21.3% never disinfect dental impressions, being the most common reason the fear of dimensional changes (25%) (figure 1). As for the prosthesis technicians, 12.5% never disinfect the impressions, mainly for considering it irrelevant (50%). Regarding the communication of the disinfection state of an impression between dentists and prosthesis technicians 58.9%
of the dentists do not inform the state of disinfection, which is in accordance with the answers from the prosthesis technicians since 82.6% are not aware of the state of disinfection.
Addition silicone and alginate impressions’ disinfection by immersion does not significantly impact the dimensional stability of the impressions (p>0.05, figure 2). All the values of dimensional changes calculated for side A were according to the ISO 19 standard 4823:2015, which states that the maximum percentage of dimensional change for elastomers should not exceed 1.5%.
Results
Disinfection of Dental Impressions: a Safe but Feared Step
Cross-infection control in dental practice is of great importance. Most microorganisms are commensal and non-pathogenic; however, some may be opportunistic and cause oral or systemic pathology. One of the possible paths of transmission is by dental impressions that contain the patient's saliva and blood and, consequently, the gypsum casts produced after them, exposing oral healthcare professionals to possible contamination (1,2). To minimize the risk of cross-infection, several health organizations such as the American Dental Association (ADA) and the Centers for Disease Control (CDC) have published guidelines recommending disinfecting dental impressions immediately after their removal from the mouth, but there are no specific guidelines concerning disinfectants (3,4). In order to achieve a more precise clinical outcome, a disinfectant for dental impression materials must preserve the dimensional stability and the surface details of both the impression and the resulting cast.
Introduction
Discussion and Conclusions Methods
The purpose of this study to evaluate the knowledge regarding disinfection procedures among prosthesis technicians and dentists, as well as to assess the impact of water wash and of four disinfectant solutions on the dimensional stability of addition silicone’ and alginate’ impressions, namely, hydrogen peroxide (3%), MD520® (Durr™), or sodium hypochlorite (1% and 5.25%).
Objectives
1. Marya CM, Shukla P, Dahiya V, Jnaneswar A: Current status of disinfection of dental impressions in Indian dental colleges: a cause of concern. Journal of infection in developing countries 2011;5:776-780; 2. Alter MJ, Kruszon-Moran D, Nainan OV, McQuillan GM, Gao F, Moyer LA, et al: The prevalence of hepatitis C virus infection in the United States, 1988 through 1994. The New England journal of medicine 1999;341:556-562. 3. From the Centers for Disease Control: Possible transmission of human immunodeficiency virus to a patient during an invasive dental procedure. JAMA: The journal of the American Medical Association 1990;264:1092-1093. 4. Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM: Guidelines for infection control in dental health-care settings--2003. MMWR Recommendations and reports : Morbidity and mortality weekly report Recommendations and reports / Centers for Disease Control 2003;52:1-61. 5. Yuzbasioglu E, Sarac D, Canbaz S, Sarac YS, Cengiz S: A survey of cross-infection control procedures: knowledge and attitudes of Turkish dentists. Journal of applied oral science: 2009;17:565-569.
References
Dimensional Stability’ ensional Stabi EvaluationSurvey on the Knowledge Survey on the Knowledge regarding Disinfection arding Disinfect Procedures
10 impressions in both alginate (Orthoprint, Zhermack™) and addition silicone (Hydrorise Putty, Zhermack™) were taken
and submitted to the following protocols:
1 1)
and 1) Unwashed
submitte nd s
d control e mitte ol;
2 1 2 2)
Unwash U 1) U 2 2)) Water
hedd ontroco ash
rr washing o ol ntro
ggfor ol;
rr 3000 secondsds;
3 2 3 3)
Water washiw W
2) W 3
3)) Immersion shi n n in
ng i n n n n 3
gfo ngg
3 3 3%
0 30 econdse or
o fo
%
%
%
%
% hydrogen ds;
ondd n
n peroxideeforr 100 minutes*s*;
4 3 4 4)
mmersion Im 3) I 4
4)) Immersion n in n n in
n n n n n n 1
% 3 1 1%
hydrogen
% h
%
%
%
%
% sodium
n peroxidep efo genn
m
m hypochlorite 1 o for e e efor
m 0 10 or or or 10
nutess ; min m 0 0
0 minutes*
; ss*;
5 4 5 5)
mmersion Im 4) I 5
5)) Immersion n in n n in
n n n n n n 5
1 5 5.
%
% 1 5 5.25
od so
%
% 5 5 25 25 2 2 %
umm hypoh di od
%
%
%
% sodium
ochloriteefoo ypo
m
m hypochlorite 0 10 o or 1
e e efor
minu 0 mm or or 10
utess ; minu
0
0 minutes*s*s*s ; 6
5 6 6)
mmersion Im 5) I 6
6)) Immersion n in n n in
.2 n 55 n n n n n MD
% 25 25 2 %% D D D D D520
%
% so 20 20 2 ®
o o
®
®( um iu d o
®((Durr m m hyh
rr rrr™)
och yp hy
))
™ for och
rr 5 oriteefooor hlo h 5
5 minutes*
0 r 010 ss*.
**washedwashedd 155 secondss withh waterr beforee andd afterr thee disinfection protocol
1 1 edd 1 ol oll.
Side A
Side B
Side A
Side B
Standardized model (ANSI/ADA specification nº18 and 19)
(Figure adapted from: Maria GA, Sanette MS. The effect of temperature on linear dimensional stability of elastomers. J Res Dent 2014;2:6-12)
The standardized The
model stand was
dardized nd
washed mod
in
el wasw ww alcohol
ashed and in alc
placed hol
in nd
a placed
greenhouse n in
at 37 a 37 37º gree
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rr 1 house nh e 1 1 minute
a e a te tee.
Questions
Practice of disinfection
Reasons for disinfection
Knowledge on the importance of dental impressions’ disinfection
1000 dentists 320 prosthesis technicians 3 months later
Response rate of 9.5%
and 7.8%, respectively
Not their responsability
Not relevant
Changes the Dimensional Stability Agreement with
Prosthesis Technicians
Others
33.30%
Dimensional Changes s -- Alginate Dimensional Changes s –– Addition Silicone
A side B side A side B side
Figure 1 – Reasons given by dentists to not disinfect dental impressions.
Figure 2 - Dimensional changes measured on sides A and B, in alginate (A) and addition silicone (B), after the different treatments.
Bars represent mean and the error bars represent standard error of the mean.
A B
22.20%
19.40%
25.00%
8.40%
(From:
http://www.savazzi.net/photo graphy/wild_leica_m420.htm)
(Adapted from: https://webllena.com/wp- content/uploads/2018/05/ImageJ.png)
