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Int Chin J Dent 2008; 8: 11-15.

Influence of water on performance of facial prosthetic adhesives
Biao Kang, DDS, PhD,a Yi-min Zhao, DDS, PhD,a Xin-yi Zhao, DDS, PhD,b Guo-feng
Wu, DDS, PhD,a and Chao Xie, DDS, PhDa
abDepartment of Prosthodontics and Department of Dental Materials, College of Stomatology, TheFourth Military Medical University, Xi’an, P. R. China
Purpose: The purpose of this study was to investigate the bond strength performance of two facial prostheticadhesives on human skin with or without immersion in water for different periods of time.
Materials and Methods: Two facial prosthetic adhesives (silicone-based Secure2 Adhesive and acrylic
polymer-based Daro B-200 ES) were used in this study. Silicone specimens (with the diameter of 5 mm)
retained with facial prosthetic adhesive were submitted to tensile bond strength on five volunteers’ forearms skinwith immersion in distilled water. According to different disposal time, four groups of 0, 1, 10, and 30 minutesof two adhesives were divided, respectively. The specimens were pulled off by use of a desktop material testerwith a crosshead speed of 1 mm/minute. Ten specimens of each group were tested, and a total of 80 tests werecarried out.
Results: Statistical analysis showed that for Secure2 Adhesive, tensile bond strength didn’t change after
immersion for 30 minutes (p>0.05), while for Daro B-200 ES, the tensile bond strength reduced significantly
after 10 minutes in water (p<0.05). Observation of the rupture mode showed that Daro-200-ES left moreadhesive residue on skin than Secure2 Adhesive did (p<0.05).
Conclusion: Considering study methodology and limitations, it could be concluded that immersion in water
didn’t influence the bond strength of silicone-based adhesive, whereas affected that of acrylic polymer-basedadhesive. (Int Chin J Dent 2008; 8: 11-15.)
Key Words: prosthetic adhesive, silicone elastomer, tensile bond strength.

Introduction
The success of facial restoration relies partially on the retention of prostheses. Facial prostheses can beretained by anatomic undercut, mechanical means, and skin adhesives or craniofacial implants.1-4 Anatomicundercut is restricted when the compromised tissue is fragile or sensitive. Mechanical retention is less popular
because of its unsightlessness. Therefore both anatomic undercut and mechanical retention are most tending to
be used as assistant means. Osseointegrated implants can be applied to facilitate retention, stability, and support
for facial prostheses used to restore head and neck defects.4 Retention with implants has been preferred in clinic,
for implant-retained facial prosthesis offers significant enhancement over an adhesive-retained prosthesis withrespect to ease of use and retention during a variety of daily activities, resulting in greater use of the prosthesis.5
Since some patients are not candidates for implant intervention (for various reasons, including tumor prognosis,
compromised tissue beds, and financial limitations), however, many of them will have to depend on prosthetic
adhesives to retain their facial prostheses.6 What’s more, adhesives are effective and commonly used with orwithout implants or magnets.
Dozens of researches have been carried out to evaluate the mechanical performance of facial prostheticadhesives,7-15 however, most of the researches focused on the bond strength of prosthetic adhesives under dry
conditions. In daily life, facial prostheses retained with prosthetic adhesives may be wetted by water, sweat,
saliva or other secretion. The influences of water on the retention of prostheses with prosthetic adhesive are notclear yet. Therefore the purpose of this study was to investigate the performance of two commercially available
facial prosthetic adhesives on human skin with immersion in water for different periods of time.

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Materials and Methods
Five male volunteers aged 23 to 29 years were recruited. This study has been obtained the subjects’ consentand approved by the Ethical Review Committee of College of Stomatology, the Fourth Military Medical
University. Before test forearms of the volunteers were washed with soap and water and cleaned with ethyl
alcohol. Test specimens were fabricated with silicone elastomer (A-2186, Lot L40698, Factor II, Lakeside, AZ,USA). Two parts of A-2186 were mixed in a 10:1 ratio by weight according to the manufacturer’s instructions.
Special care was exercised to minimize bubble attraction. The mixture was packed into a two-piece dental stone
mode immediately after mixing and cured at room temperature. The diameter of the silicone specimen was 5mm according to Polyzois et al.9
Table 1.

Facial prosthetic adhesives used in this study.

Adhesive

Composition

Manufacturer

Lot number

Secure2 Adhesive

Silicone, Ethyl acetate,Tetra(trimethylsiloxy) silane, Xylene

Factor II, Lakeside, AZ, USA

R2266927-6

Daro B-200 ES

Acrylic polymer, Water, Ammonia,Residual monomers

Factor II

RLES507051

Two facial prosthetic adhesives, Secure2 Adhesive and Daro B-200 ES, used in this tudy are shown in Table 1.
Secure2 Adhesive is a silicone-based adhesive and Daro B-200 ES an acrylic polymer-based adhesive. The
adhesives were applied in a thin layer on the silicone specimen and allowed to dry according to themanufacturer’s instructions. The silicone specimens were adhered to the volunteers’ forearms skin 5 to 10 cm
far away from their wrists, loaded with a pressure of 500 g for a 20-second period. The specimens retained withadhesives were submitted to tensile bond strength randomly with immersion in distilled water at 32±2˚C (Fig. 1).
According to different disposal time in water, 1, 10, and 30 minutes groups of two adhesives were divided,respectively. The specimens tested without immersion in water (0 minute group) were taken as control. Tenspecimens of each group were tested, two specimens once a time, and a total of 80 pull-off tests were carried out.
The room temperature was 23˚C and the relative humidity was 65%. The tests were initiated by use of a desktop
material tester (EZ-test, Shimadzu, Kyoto, Japan) with a crosshead speed of 1 mm/minute (Fig. 2). After test
forearms of the volunteers were immediately washed with soap and water and cleaned with ethyl alcohol again.

Fig. 1.
Fig. 2.

1
The forearm of the volunteer with specimens immersed in water.
Tensile force applied to detach the silicone specimen from the skin.

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The amount of tensile force F required to rupture the bond was used to calculate the tensile bond strength Ts
according to the formula Ts=F/S (kPa), where S is the bonded surface area of the test specimen. Three-way
analysis of variance (ANOVA) and LSD test were used to analyze the data of bond strength. The location of therupture was observed, for instance, either interfacial between adhesive and skin (s) or between adhesive andsilicone specimen (prosthesis) (p). To denote whether failure occurs at the silicone specimen or skin interfaces,
Fisher exact test was used to analyze the data. P-values less than 0.05 were regarded as significant. All
statistical analyses were done using statistical software (SPSS for Windows, Version 12.0, SPSS, Chicago, IL,USA).

Results
The tensile bond strengths of two adhesives with immersion in water for 0, 1, 10, and 30 minutes were 52.6,51.4, 51.7, 50.6 kPa (Secure2 Adhesive) and 23.7, 22.3, 14.8, 10.2 kPa (Daro B-200 ES), respectively, which
was shown in Table 2. Secure2 Adhesive showed higher bond strength than Daro B-200 ES did (p<0.01).
Statistical analysis showed that for Secure2 Adhesive, tensile bond strength didn’t change after immersion for 30
minutes (p>0.05), while for Daro B-200 ES, the tensile bond strength reduced significantly after 10 minutes inwater (p<0.05).
After the specimens bonded with Daro B-200 ES were immersed in water for more than 1 minute, around thefringe of specimen/skin bonding interface white emulsion was observed. With the time prolonged, the white
exudation increased and diffused gradually. Observation of the failure mode showed that Secure2 Adhesive
mainly failed at the adhesive/skin interface (S) and left adhesive residue on silicone, whereas Daro B-200 ES
mainly failed at the silicone/adhesive interface (P) with white adhesive residue left on skin.
Table 2.

Tensile bond strength in kPa and failure mode of two prosthetic adhesives (n=10).

Immersion in water
0 minute
Adhesive
Mean SD P/S

1 mimute
Mean SD P/S

10 minutes
Mean SD P/S

30 minutes
Mean SD P/SSecure2 Adhesive

52.6 8.4

3/7

51.4 7.9

4/6

51.7 8.6

3/7

50.6 9.1

2/8

Daro B-200 ES

23.7 6.9

6/4

22.3 6.2

7/3

14.8 7.2

8/2

10.2 7.5

8/2

SD, Standard deviation; P, Failed at the silicone/adhesive interface; S, Failed at the adhesive/skin interface.

Discussion
Traditional facial prosthetic adhesives are commonly classified as double-sided tapes, pastes, liquids, andspry-on adhesives.16 According to the base of the adhesives, most of commercially available adhesives can beclassified into two categories: silicone-based adhesive and acrylic polymer-based adhesive.13 In the current
study, Secure2 Adhesive is a silicone-based adhesive and Daro B-200 ES is an acrylic polymer-based adhesive(Table 1). The shape of the silicone specimen was designed and fabricated according to Polyzois et al.9 and ourprevious findings. To facilitate the test of tensile bond strength, the specimen was modified as a round patchwith a bar on it to attach with a custom clasp (Fig. 2).
temperature and shell temperature.

17

The temperature of human body includes core

When the room temperature is 23˚C, the core temperature of human body

is 36.8˚C and the shell temperature is usually 32˚C. So as to simulate the condition of normal human skin, theforearms of the volunteer with specimens were immersed in distilled water at 32˚C.

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According to the manufacturer’s instruction, Daro B-200 ES changed from white emulsion to clear adhesive
film within the application procedure. While after immersion in water for more than 1 minute, white emulsion
exudation was observed around the bonding fringe of specimen. This phenomenon was only noted in the usageof acrylic polymer-based adhesive, Daro B-200 ES. This could be due to the emulsifier in this kind of adhesive
was dissolved by water. During the synthesis of acrylic polymer-based adhesive, emulsifier is usually used to
combine the oil-phase and water-phase to graft each other.

Besides, adhesive film expanded in aqueous

environment after water absorption, which weakened the bonding interface. This result was proved by theobservation of the rupture mode of both adhesives.

For example, Secure2 Adhesive mainly failed atadhesive/skin interface and left adhesive residue on silicone, whereas Daro B-200 ES failed at thesilicone/adhesive interface with white adhesive residue left on skin. Water absorption of acrylic polymer-based
adhesives reflects the capacity for water resistance. The higher water absorption, the lower capacity for water
resistance and vice versa.18 Water absorption of two kinds of traditional facial prosthetic adhesives needs to beevaluated further. New acrylic polymer-based adhesive modified with organic siloxane could be a direction.
With the time of immersion in water prolonged, tensile bond strength of Secure2 Adhesive didn’t change,
whereas that of Daro B-200 ES reduced significantly after 10 minutes immersion in water. Considering study
methodology and limitations, it could be concluded that immersion in water didn’t influence the bond strength ofsilicone-based adhesive, whereas affected that of acrylic polymer-based adhesive. On one side, water can beused to wash off the acrylic polymer-based adhesive residue from skin, on the other side, in daily life facial
prostheses shouldn’t be exposed in water or sweat for a long period of time.
Haug et al.11 reported the variance of bond strength from different subjects for different skin conditions. In
the present study, no significant difference of bond strength for the same adhesive was found among the subjects.
This could be due to the reason that the five volunteers were all young males with similar skin conditions, andthe tests were carried out on both of the volunteers’ forearms randomly. In this study, influence of water fromoutside on two prosthetic adhesives was investigated. When facial prostheses are adhered to normal skin withprosthetic adhesive, the secretion of sweat or other body liquid may influence the bonding interface inside.
Therefore, tests of the volunteers wearing silicone specimens to imitate the sweaty condition are necessary to beinvestigated in future.
Acknowledgments
The authors would like to acknowledge the volunteers for their generosity. This study was supported by a key project
grant from the National Natural Science Foundation of China (No. 30630066).

References
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Correspondence to:
Dr. Yi-min Zhao
Department of Prosthodontics, College of Stomatology, The Fourth Military Medical University
145 Changle Xi Road, Xi’an, 710032, P. R. China
Fax: +86-29-84776465 E-mail: zhaoym@fmmu.edu.cn
Received December 28, 2007. Accepted March 31, 2008.
Copyright ©2008 by the International Chinese Journal of Dentistry.

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