Victorinox introduced the toothpick and tweezers into the Swiss Army Knife around 1902. Until the 1930s, toothpicks were carved from ivory/horn.
Each company has two main variations based on the size of the model into which they fit. The designs have changed slightly over the years.
Related Page: Tweezers
External Resource: SOSAK: Toothpick Comparison: The Smallest Detail, September 30, 2007
Victorinox
The image shows the standard toothpicks from a 58mm(top), and a 91mm(bottom), sized Victorinox model.
The '91mm' toothpick is slighly larger and has an angled-head, making it only fit properly into the scale on one side of the knife. It also fits 111mm and 130mm (Delémont Collection) models. The '58mm' toothpick is slightly smaller and has a symmetrical head so will fit into either scale of a 58mm model. The 58mm version is also used in the 74mm models and the SwissCard.
The nubs on the surfaces of the toothpick help to hold it into place in the scale.
At some stage in the past Victorinox issued a variant of the 91mm toothpick with a small hook on the tip. It is not known precisely when (or in which models) these toothpicks were issued (for example, it was used in 111mm Picknicker model released in about 2000).
In 2021, toothpicks in four new colors: red, green, blue and black became available in both sizes.
Wenger
The image shows the standard toothpicks from a 65mm and a 85mm sized Wenger model.
Note the angled head of the '85mm' toothpick, making it only fit properly into the scale on one side.
The '65mm' toothpick will fit into either scale of a 65mm model and will also fit into 75mm models.
The little nubs sticking out on the sides help to hold the toothpick into the scale.