"Daily chewing of a tough chewing material consisting of resin from a pine tree (Mastix from the island of Chios, Greece) was instituted in 13 children (aged 7–12 years) with long-face morphology. The chewing exercise therapy was maintained for one year and aimed at revealing the possibility of strengthening the masticatory muscles and influencing facial growth.
Masticatory muscle strength was monitored by measurement of bite force and electromyo-graphic recording of the activity of the anterior temporal and masseter muscles during biting and chewing. The facial morphology was recorded with profile cephalograms and dental casts.
During the one-year experimental period, there was a significant increase in bite force and muscle activity during maximal bite. The change was already evident at the first control recording 3 months after the start of the chewing exercise therapy. The muscle activity during chewing of apple and peanuts did not change significantly.
The facial growth was characterized by anterior mandibular rotation in 9 of 12 cases while a posterior rotation occurred in 2 cases. The anterior rotation was, on average, 2.5 degrees and thus considerably greater than would be expected during normal growth. There were no signs of reduced vertical growth of the maxilla, a reduced rate of molar eruption or increased growth of the mandible."
