Authors: Goodman A, Schilder H, Aldrich W.
Title: The thermomechanical properties of gutta-percha. II. The history and molecular chemistry of gutta-percha.
Journal: Oral Surg Oral Med Oral Pathol
Date: Jun 1974
Citation: 37(6):954-61
Category: Obturation
Evidence-based Ranking: 5
Purpose/Objectives: To review early uses of gutta percha and its molecular chemistry

Discussion: History- The Malays and the Chinese were first to use Gutta Percha, followed in Europe by a description in 1656 by the family of Trandescants in a collection called Trandescants's Arc. At that time it was referred to as Mazer Wood. It was then reintroduced as Gutta percha in the 1840's. Gutta percha was used in the first successful insulation for an underwater telegraph line. GP was also used in the manufacturing of corks, cements, paper, maps, boats, and even golf balls. However, rubber soon dispelled GP in many aspects. Thermomechanical properties- Gutta Percha is a naturally high-molecular weight polymer of isoprene. GP exists in the trans state, meaning the CH2 groups are on opposite sides of the isoprene chains, resulting in a more linear arrangement. This gives GP harder, more brittle and less elastic properties when compared to natural rubber, which exists in the cis state. In 1942 C.W. Bunn explained how GP can exist in two different crystalline forms, alpha and beta. The alpha state is the natural form, and when heated above 65 C it turns amorphous. If cooled at .5 C/hr it can return to the alpha form, and if not it turns into the commercial beta form. Beta GP becomes amorphous at 56 C. Differences in these temperatures have been reported, most likely due to impurities. The main difference between the two structurally is the molecular repeat distance, which is smaller with the beta form.

ReviewerÂ’s Comments: Good historical review on the uses of Gutta Percha, and at the point in time, a good review on the thermomechanical properties.