Dental putty is a silicone-based polymer system used in dentistry. This material is typically a two-part mixture, consisting of a base and a catalyst, which react when combined to form a firm, elastic solid. Consumers encounter dental putty in two main applications: creating accurate molds for custom restorations, and serving as a provisional compound for temporary repairs. The durability and lifespan of the material vary significantly depending on whether it is an unmixed product, a hardened impression, or a temporary restoration inside the mouth.
Shelf Life of Unopened Putty
The longevity of dental putty before use is its shelf life, typically between 12 and 24 months from the date of manufacture. Manufacturers formulate the material to remain chemically stable during this period, provided it is stored under specific conditions. The chemical components can degrade over time even when sealed. To maintain this lifespan, the unmixed putty must be kept in a cool, dry, and dark location, away from direct sunlight and excessive heat. Heat can prematurely activate or destabilize the catalyst, while moisture negatively affects the base material. Using expired or improperly stored putty risks a failed outcome, such as the material not setting completely or setting too quickly, leading to an inaccurate impression.
Stability of Dental Impressions
Once mixed, molded, and removed from the mouth, dental putty transitions into a dental impression. The stability of this hardened mold is important because it serves as the negative replica used to fabricate permanent restorations like crowns or veneers. Modern materials, such as addition silicone (Polyvinyl Siloxane or PVS), exhibit excellent dimensional stability once set. This stability is due to the polymerization reaction that forms a highly cross-linked, elastic structure. PVS impressions maintain their accuracy for a significant period, often up to seven days, without distortion. This extended stability allows for the shipping and processing of the impression at a dental laboratory. However, less stable materials may require the impression to be scanned or poured into a model within a few hours to prevent shrinkage or expansion from compromising the final appliance’s fit.
Longevity of Temporary Dental Repairs
For consumers, the most common use of dental putty is as a temporary repair, such as a provisional filling or an adhesive for a loose crown. This application is strictly short-term, designed to protect the tooth until a dental professional can provide a permanent solution. The expected lifespan of these temporary repairs is highly variable, typically ranging from a few days to a maximum of six to eight weeks. The material used is intentionally softer and less durable than permanent restorations to allow for easy removal by a dentist. Failure occurs when the putty cracks, wears down, or dislodges completely, often due to chewing forces. Temporary fillings in the back molars are particularly susceptible to premature wear. Treating these materials as a long-term fix is ill-advised, as failure exposes the underlying tooth to decay and infection.
Factors Influencing Putty Degradation
Several factors can accelerate the breakdown or compromise the performance of dental putty across all its applications. One common cause of failure in two-part systems is an incorrect mixing ratio of the base and catalyst, which prevents the material from achieving its full strength. For materials requiring manual mixing, inadequate kneading can result in uncured spots within the finished impression. Temperature exposure is also a significant factor, as excessive heat can cause premature setting or dimensional shrinkage in impressions. Within the mouth, chemical factors contribute to the breakdown of temporary repairs, as the constant presence of saliva, oral bacteria, and acids can hydrolyze the material’s polymer matrix. Additionally, strong mouthwashes or cleaning agents can chemically degrade the surface of the putty, shortening the lifespan of a temporary repair or the accuracy of a stored impression.