Workers: Tania Sethi, Dr Mohit Kheur*, Dr Trevor Coward**, Colin Haylock***
* Professor, Prosthodontics, M.A Rangoonwala Dental College,Pune
** Head, Dept of Maxillofacial Prosthetics, Kings College, London,UK
*** Dept of Maxillofacial Prosthetics, Kings College, London,UK
Statement of Purpose
Maxillofacial prosthetics plays a key role in the over all rehabilitation of patients who have undergone extensive surgery following tumour resections and trauma. Silicone materials have over taken conventional acrylic resins and have become the materials of choice for the fabrication of such maxillofacial prostheses. This is mainly because of their clinical inertness, strength, durability, ease of manipulation and the comfort that they offer to patients, compared to the older materials. However such prostheses need to be periodically replaced. The main reason for replacement is the degradation of its colour and physical properties. The rate and amount of these changes can be variable depending on the climatic conditions and environment that the prosthesis is worn in. Such changes could also occur in varying proportions depending upon whether the material is cured at room temperature or by the application of heat in a hot air oven.
There is no report in the literature of the effect of the warmer, more humid Indian sub- continental environment on the rate of degradation of silicones using the above mentioned parameters and hence this study has been designed.
MATERIALS STUDIED
a) M 511 – 10: 1 platinum based system (Principality Medical, UK)
b) Z004 – 1:1 platinum based system (Principality Medical, UK)
TESTING APPARATUS
Hardness test – IRHD (Int Rubber Hardness test Device ) I have put a picture at the top.
FABRICATION OF THE SAMPLES
Sample size
A total of 60 samples were fabricated for each material.
30 samples were denoted as Group A and 30 samples as Group B.
Group A included 30 samples of each material made by room temperature curing.
Sub Group A1 – Samples of M511 by room temperature curing – Total 30 samples
Sub Group A2 – Samples of Z 004by room temperature curing – Total 30 samples
Group B included 30 samples of each material made by heat application.
Sub Group B1 – Samples of M511 by heat application – Total 30 samples
Sub Group B2 – Samples of Z 004 by heat application – Total 30 samples
Test and Control Group:
The samples are shown above.
Test group - 13 samples each from Sub Groups A1, A2 , B1, B2. – For the Patient study.
10 samples each from Sub groups A1 A2 B1, B2 – Weathered on roof top.
Control Group – 7 samples each – Sub Groups A1, A2 , B1, B2.
Manipulation of the material -
Each of the materials were handled in strict compliance with the manufacturers instructions. To achieve maximum consistency among specimens within the same Group, all such specimens were processed together.
The base and the catalyst was weighed using an electronic weighing scale and vacuum mixed.
The ratio used was 182 gm base and 18 gm of catalyst for the M 511 material.
The ratio for Z 004 was 100gm base and 100 gm of catalyst.
Each of the 200 gm of silicone were coloured using
Dry earth pigments (Cosmesil pigments, Technovent Ltd UK)
Umber-0.1gm
Dark yellow– 0.1 gm
Blue- 0.01 gm
Red-0.01gm
(This gave us a shade resembling Asian skin colours)
Thus from the same mix, the silicone was divided into 2 groups.
The Group A samples were left to cure at room temperature for 10 hours
The Group B samples were placed in a hot air oven at 85 deg Celsius for 1 hour.
STORAGE OF THE SAMPLES
7 samples that form the Control group were stored in an airtight container free from exposure to light and at ambient room temperature throughout the duration of the study.
10 samples in the study groups A and B of each material type were suspended from wooden racks by stainless steel suture material and placed on the roof of the Dental Institute.
13 samples each, from Group A and Group B were worn on the wrist of Dental students in the form of an attractive bracelet. Each bracelet had 1 sample each from Groups A1, A2, B1 B2. This was done to simulate the use of prosthesis on human skin.
TESTING PROCEDURE
Testing of the samples, (for both control group and the test groups) was done for
a) The colour change and
b) Change in hardness.
These changes were studied by repeated testing which was done at 3 stages –
Stage 1 - Immediately after curing. This time is to be used as the baseline time.
Stage 2 - 3 months from baseline.
Stage 3 - 9 months from baseline.
Hardness test – Hardness Was calculated by applying the IRHD at 3 points on each sample at every time interval mentioned above. The mean was taken as the mean hardness of each sample and the change was calculated at each of the intervals mentioned above.
(The IRHD is a very sensitive computerized hardness testing device that can measure hardness up to 2 decimal points. The previous studies using Shore A Durometers have measured hardness with certain limitations like limited sensitivity, less accuracy and are subject to human error while using the machine. The IRHD has a computer driven Shore A indenter)
The results thus were analyzed, subjected to a statistical analysis and appropriate conclusions were drawn.
My Results and Conclusions:
Overall, at 3-months the average hardness change in both the materials was significantly approximately similar.
However,
Material 2 Simweathering samples had smaller change compared to Material 1 samples.
In general, at 6-months the average hardness change in material 1 (M 511) was significantly lower compared to Material 2 (Z 004).
However,
Material 1 Cooled had smaller change compared to Material 2 cooled.
Material 1 Clinical and Control samples showed smaller change compared to Material 2 Clinical and Controls samples.
Overall, at 9-months there was no statistically significant difference in hardness change between the two materials.
However,
Material 1 Cooled had smaller change compared to Material 2 cooled.
Clinical and Control samples of Material 1 Showed significantly smaller hardness change compared to respective samples of Material 1.
Simweathiering sample of Material 2 Showed significantly smaller hardness change compare to Control sample of Material 1.
References:
1. Interactions of pigments and opacifiers on color stability of MDX4-4210/type A maxillofacial elastomers subjected to artificial aging
Sudarat Kiat-amnuay, Trakol Mekayarajjananonth, John M. Powers, Mark S. Chambers, James C. Lemon
J Prosthet Dent 2006 ;95, 3, 249-257
2. Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers
Mark W. Beatty, Gordon K. Mahanna, Wenyi Jia
J Prosthet Dent 1999 ; 82, 4, 441-446
3. In vitro evaluation of color change in maxillofacial elastomer through the use of an ultraviolet light absorber and a hindered amine light stabilizer
Ngoc H. Tran, Mark Scarbecz, John J. Gary
J Prosthet Dent 2004 ;91,5, 483-490
4. Color stability of facial silicone prosthetic polymers after outdoor weathering
Gregory L. Polyzois
J Prosthet Dent 1999 ; 82, 4,447-450
5. Physical properties of a silicone prosthetic elastomer stored in simulated skin secretions
Gregory L. Polyzois, Petroula A. Tarantili, Mary J. Frangou, Andreas G. Andreopoulos
J Prosthet Dent 2000 ; 83, 5,572-577
6. Accelerated color change in a maxillofacial elastomer with and without pigmentation
John J. Gary, Eugene F. Huget, Larry D. Powell
J Prosthet Dent 2001 ; 85, 6, 614-620
7. Color stability and colorant effect on maxillofacial elastomers. Part III: Weathering effect on color
Steven P. Haug, Carl J. Andres, B. Keith Moore
J Prosthet Dent 1999 ; 81,4, 431-438
8. Color stability and colorant effect on maxillofacial elastomers. Part I: Colorant effect on physical properties
Steven P. Haug, Carl J. Andres, B. Keith Moore
J Prosthet Dent 1999 ; 81,4,418-422)
9. Color stability and colorant effect on maxillofacial elastomers. Part II: Weathering effect on physical properties
Steven P. Haug, B. Keith Moore, Carl J. Andres
J Prosthet Dent 1999 ; 81,4, 423-430
* Professor, Prosthodontics, M.A Rangoonwala Dental College,Pune
** Head, Dept of Maxillofacial Prosthetics, Kings College, London,UK
*** Dept of Maxillofacial Prosthetics, Kings College, London,UK
Statement of Purpose
Maxillofacial prosthetics plays a key role in the over all rehabilitation of patients who have undergone extensive surgery following tumour resections and trauma. Silicone materials have over taken conventional acrylic resins and have become the materials of choice for the fabrication of such maxillofacial prostheses. This is mainly because of their clinical inertness, strength, durability, ease of manipulation and the comfort that they offer to patients, compared to the older materials. However such prostheses need to be periodically replaced. The main reason for replacement is the degradation of its colour and physical properties. The rate and amount of these changes can be variable depending on the climatic conditions and environment that the prosthesis is worn in. Such changes could also occur in varying proportions depending upon whether the material is cured at room temperature or by the application of heat in a hot air oven.
There is no report in the literature of the effect of the warmer, more humid Indian sub- continental environment on the rate of degradation of silicones using the above mentioned parameters and hence this study has been designed.
MATERIALS STUDIED
a) M 511 – 10: 1 platinum based system (Principality Medical, UK)
b) Z004 – 1:1 platinum based system (Principality Medical, UK)
TESTING APPARATUS
Hardness test – IRHD (Int Rubber Hardness test Device ) I have put a picture at the top.
FABRICATION OF THE SAMPLES
Sample size
A total of 60 samples were fabricated for each material.
30 samples were denoted as Group A and 30 samples as Group B.
Group A included 30 samples of each material made by room temperature curing.
Sub Group A1 – Samples of M511 by room temperature curing – Total 30 samples
Sub Group A2 – Samples of Z 004by room temperature curing – Total 30 samples
Group B included 30 samples of each material made by heat application.
Sub Group B1 – Samples of M511 by heat application – Total 30 samples
Sub Group B2 – Samples of Z 004 by heat application – Total 30 samples
Test and Control Group:
The samples are shown above.
Test group - 13 samples each from Sub Groups A1, A2 , B1, B2. – For the Patient study.
10 samples each from Sub groups A1 A2 B1, B2 – Weathered on roof top.
Control Group – 7 samples each – Sub Groups A1, A2 , B1, B2.
Manipulation of the material -
Each of the materials were handled in strict compliance with the manufacturers instructions. To achieve maximum consistency among specimens within the same Group, all such specimens were processed together.
The base and the catalyst was weighed using an electronic weighing scale and vacuum mixed.
The ratio used was 182 gm base and 18 gm of catalyst for the M 511 material.
The ratio for Z 004 was 100gm base and 100 gm of catalyst.
Each of the 200 gm of silicone were coloured using
Dry earth pigments (Cosmesil pigments, Technovent Ltd UK)
Umber-0.1gm
Dark yellow– 0.1 gm
Blue- 0.01 gm
Red-0.01gm
(This gave us a shade resembling Asian skin colours)
Thus from the same mix, the silicone was divided into 2 groups.
The Group A samples were left to cure at room temperature for 10 hours
The Group B samples were placed in a hot air oven at 85 deg Celsius for 1 hour.
STORAGE OF THE SAMPLES
7 samples that form the Control group were stored in an airtight container free from exposure to light and at ambient room temperature throughout the duration of the study.
10 samples in the study groups A and B of each material type were suspended from wooden racks by stainless steel suture material and placed on the roof of the Dental Institute.
13 samples each, from Group A and Group B were worn on the wrist of Dental students in the form of an attractive bracelet. Each bracelet had 1 sample each from Groups A1, A2, B1 B2. This was done to simulate the use of prosthesis on human skin.
TESTING PROCEDURE
Testing of the samples, (for both control group and the test groups) was done for
a) The colour change and
b) Change in hardness.
These changes were studied by repeated testing which was done at 3 stages –
Stage 1 - Immediately after curing. This time is to be used as the baseline time.
Stage 2 - 3 months from baseline.
Stage 3 - 9 months from baseline.
Hardness test – Hardness Was calculated by applying the IRHD at 3 points on each sample at every time interval mentioned above. The mean was taken as the mean hardness of each sample and the change was calculated at each of the intervals mentioned above.
(The IRHD is a very sensitive computerized hardness testing device that can measure hardness up to 2 decimal points. The previous studies using Shore A Durometers have measured hardness with certain limitations like limited sensitivity, less accuracy and are subject to human error while using the machine. The IRHD has a computer driven Shore A indenter)
The results thus were analyzed, subjected to a statistical analysis and appropriate conclusions were drawn.
My Results and Conclusions:
Overall, at 3-months the average hardness change in both the materials was significantly approximately similar.
However,
Material 2 Simweathering samples had smaller change compared to Material 1 samples.
In general, at 6-months the average hardness change in material 1 (M 511) was significantly lower compared to Material 2 (Z 004).
However,
Material 1 Cooled had smaller change compared to Material 2 cooled.
Material 1 Clinical and Control samples showed smaller change compared to Material 2 Clinical and Controls samples.
Overall, at 9-months there was no statistically significant difference in hardness change between the two materials.
However,
Material 1 Cooled had smaller change compared to Material 2 cooled.
Clinical and Control samples of Material 1 Showed significantly smaller hardness change compared to respective samples of Material 1.
Simweathiering sample of Material 2 Showed significantly smaller hardness change compare to Control sample of Material 1.
References:
1. Interactions of pigments and opacifiers on color stability of MDX4-4210/type A maxillofacial elastomers subjected to artificial aging
Sudarat Kiat-amnuay, Trakol Mekayarajjananonth, John M. Powers, Mark S. Chambers, James C. Lemon
J Prosthet Dent 2006 ;95, 3, 249-257
2. Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers
Mark W. Beatty, Gordon K. Mahanna, Wenyi Jia
J Prosthet Dent 1999 ; 82, 4, 441-446
3. In vitro evaluation of color change in maxillofacial elastomer through the use of an ultraviolet light absorber and a hindered amine light stabilizer
Ngoc H. Tran, Mark Scarbecz, John J. Gary
J Prosthet Dent 2004 ;91,5, 483-490
4. Color stability of facial silicone prosthetic polymers after outdoor weathering
Gregory L. Polyzois
J Prosthet Dent 1999 ; 82, 4,447-450
5. Physical properties of a silicone prosthetic elastomer stored in simulated skin secretions
Gregory L. Polyzois, Petroula A. Tarantili, Mary J. Frangou, Andreas G. Andreopoulos
J Prosthet Dent 2000 ; 83, 5,572-577
6. Accelerated color change in a maxillofacial elastomer with and without pigmentation
John J. Gary, Eugene F. Huget, Larry D. Powell
J Prosthet Dent 2001 ; 85, 6, 614-620
7. Color stability and colorant effect on maxillofacial elastomers. Part III: Weathering effect on color
Steven P. Haug, Carl J. Andres, B. Keith Moore
J Prosthet Dent 1999 ; 81,4, 431-438
8. Color stability and colorant effect on maxillofacial elastomers. Part I: Colorant effect on physical properties
Steven P. Haug, Carl J. Andres, B. Keith Moore
J Prosthet Dent 1999 ; 81,4,418-422)
9. Color stability and colorant effect on maxillofacial elastomers. Part II: Weathering effect on physical properties
Steven P. Haug, B. Keith Moore, Carl J. Andres
J Prosthet Dent 1999 ; 81,4, 423-430
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