Pseudoprognathism frequency and masseter muscle activity in operated cleftlip patients

yBackground: As a consequence of a growth inhibition of middle third of the face, cleft lip surgery could lead to a pseudoprognathism. However, this i s not always the case. Also, when facial architecture is changed, the activ ity of muscles such as the masseter could be disturbed. Aim: To study masse ter electromyographic activity in operated cleft lip patients. Materials an d methods: Forty two patients with cleft lip (25 male, aged 13 to 35 years old) were studied. All were operated during their first year of lift. An el ectromyography of masseter muscle was performed and from a teleradiography, ANB and Gonion angles were obtained. Forty healthy subjects conformed the control group. Results: The sample was divided in two groups. A group of 20 patients had a significantly lower EMG voltaje that control subjects (662 +/- 228 and 1511 +/- 340 muV respectively, p < 0.001). Only seven patients had an anteriorly inverted bite with a mean ANB of + 1.7 and a mean molar r elation of -4.8, figures that confirm the presence of pseudoprognasthism. C onclusions: Eighty three percent of cleft lip patients have a lower massete r activity.