EC Dental Science

Introduction: Complete dentures are a pair of acrylic plates simulating upper and lower alveolar ridges bearing a full set of maxillary and mandibular teeth that impart aesthetics to the face and rehabilitate the function of mastication for people who have lost all teeth.

Prolonged use of complete denture leads to pressure resorption of the alveolar ridges leading to denture instability. An unstable denture is incapable of even distribution of masticatory stresses leading to concentration of load at certain specific areas creating pressure points. These areas are often painful due to ulceration, inflammation or injury to oral mucosa from denture trauma.

Here comes in the role of denture reliners. Denture soft liners go a long way in enabling a dentist to ensure comfort and protection to a denture wearing patient with special needs.

Aim: To evaluate the changing hardness values of denture soft liners when stored for varying duration in different commonly available storage media.

Methodology: A total of 384 disc shaped samples of denture soft liners have been fabricated using ISO directives. These samples have been divided into groups I, II and III of 128 each, respectively made out of Mollosil (Detax, Germany), Reline Soft (GC, Japan) and Coe Soft (GC, Japan). Further, every group have been divided into subgroups A, B, C and D consisting of 32 samples each which have been stored in artificial saliva, tap water, RO water and distilled water respectively. Again 32 samples in each subgroup have been divided into batches of 8 and studied at 4 different time intervals of 32 hours post fabrication, 7 days post immersion, 30 days post immersion and 90 days post immersion in each storage medium.

Results: The data was analyzed using two way ANOVA. The mean Shore A hardness just after fabrication of the samples (Day 2) ranges between 38.4 ± 0.2 to 42.7 ± 0.4. When immersed in storage media, the values indicate increase in Shore A hardness and the minimum increase in hardness is seen in artificial saliva. The maximum increase in hardness is seen in tap water.

Conclusion: It was concluded that the hardness of GC Coe Soft showed minimum changes over time and the best material for storage according to this study is artificial saliva.

Keywords: Denture Soft Liner; Storage Media; Hardness; Plasticizers; Complete Denture; Pressure Ulcers

1. Hong Guan., et al. “Influence of storage methods on the surface roughness of tissue conditioners”. Dental Materials Journal2 (2008): 153-158.
2. Liao Wen-Chien. “The chemical degradation of denture soft lining materials: a study of the interactions between denture soft lining materials and food simulating liquids”. (2006).
3. Kalamalla Ayappa Saran Babu. “A Beginners guide for soft liners- Mini review”. Journal of Pharmaceutical Sciences and Research12 (2019): 3802-3805.
4. Kreve Simone and Andréa C Dos Reis. “Denture Liners: A Systematic Review Relative to Adhesion and Mechanical Properties”. The Scientific World Journal (2019): 6913080.
5. Chladek Grzegorz., et al. “Long-Term Soft Denture Lining Materials”. Materials8 (2014): 5816-5842.
6. Mancuso Daniela Nardi., et al. “Evaluation of hardness and colour change of soft liners after accelerated ageing”. Primary Dental Care: Journal of the Faculty of General Dental Practitioners (UK)3 (2009): 127-130.
7. Mese Ayse and Kahraman G Guzel. “Effect of storage duration on the hardness and tensile bond strength of silicone- and acrylic resin-based resilient denture liners to a processed denture base acrylic resin”. The Journal of Prosthetic Dentistry2 (2008): 153-159.
8. Khaledi AAR., et al. “Effect of Food Simulating Agents on the Hardness and Bond Strength of a Silicone Soft Liner to a Denture Base Acrylic Resin”. The Open Dentistry Journal 9 (2015): 402-408.
9. Qudah S., et al. “The effect of thermocycling on the hardness of soft lining materials”. Quintessence International7 (1991): 575-580.
10. Polyzois GL and M J Frangou. “Influence of curing method, sealer, and water storage on the hardness of a soft lining material over time”. Journal of Prosthodontics: Official Journal of the American College of Prosthodontists1 (2001): 42-45.
11. Wilson W Chase. “Tissue conditioning utilizing dynamic adaptive stress”. The Journal of Prosthetic Dentistry5 (1961): 804-815.
12. Aloul Raed K and Chiayi Shen. “The influence of plasticizer loss on the viscoelasticity of temporary soft liners”. Journal of Prosthodontics: Official Journal of the American College of Prosthodontists4 (2002): 254-262.
13. McCarthy JA and JB Moser. “Mechanical properties of tissue conditioners. Part I: theoretical considerations, behavioral characteristics, and tensile properties”. The Journal of Prosthetic Dentistry1 (1978): 89-97.
14. Nowakowska-Toporowska Agnieszka., et al. “Changes in hardness of addition-polymerizing silicone-resilient denture liners after storage in artificial saliva”. The Journal of Prosthetic Dentistry2 (2019): 317-321.
15. Malheiros-Segundo A DeL., et al. “Effect of a Denture Cleanser on Hardness, Roughness and Tensile Bond Strength of Denture Liners”. Brazilian Journal of Oral Sciences26 (2008): 1596-1501.