The late erudite father Thomas Häberle, an eminent but little known Swiss naturopath, used olive oil massages to great effect in a number of illnesses. He stressed that he reaped great successes using olive oil for diseases of the bones and head, writing that olive oil is able to penetrate even the hardest bones and bring healing where it is needed. For this reason it seems ideal to use for oil pulling.
Father Thomas Häberle has left us three small but information-packed books on natural healing two of which have been translated into English, Helping & Healing and Counselling & Curing. Luckily, they are available (and inexpensively at that) via Abebooks.
1 One person actually reported that swishing with olive oil straightened his teeth! And a 57-year-old female who had been swishing with organic extra virgin olive oil for 15-20 minutes for six months not only experienced her toothache disappearing and her mouth feeling "dentist-clean" but also saw further amazing benefits: two teeth that had been injured when she was eight and had subsequently darkened were beginning to get lighter (after she had tried bleaching and veneering to no avail since the veneers had worn off again). Additionally her jawline benefitted, taking on a firmer contour (reported on Christmas 2014).
It's truly amazing that teeth that have started to darken (where the pulp typically is considered to be "dead" or at least dying) apparently can be revitalized by (olive) oil pulling.