Question
My 21 month old son has a vocabulary of +/- 5 words. He still can't imitate animal sounds (except cat, cow and lion and they all sound the same, though the volume differs) or make simple sounds like /ta/, /ba/, or /o/ sounds. I took him to a speech thera
Answer
The speech therapist that you saw provided good advice. Your child needs a neurological evaluation and this is why the therapist did not use the full two hours scheduled for the evaluation.
What you describe about your son's bite is an anterior open bite. A 3 mm space between upper and lower front teeth would not account for a vocabulary of only 5 words at age 21 months. Most of the sounds that a child of 21 months should be making would not require closure of the bite at the front of the mouth. I would expect that with a 3 mm anterior open bite, your child protrudes his tongue between the front teeth as he attempts speech sound productions. If so, this is a normal adaptation to an open bite and also represents a normal lingual function at this age.
With regard to your question about jaw growth, yes, the jaws are still developing. The upper jaw reaches adult size by around age 8 years, although there is usually a small amount of additional growth continuing to age 12. The lower jaw grows more continuously up to around age 16, with a pubertal growth spurt around age 12 in the growth process. In many individuals, additional growth of the lower jaw is seen into the 20's. The growth process for the jaws may not result in spontaneous closure of the open bite.
From a dental standpoint, I'm not worried about any possible relationship at present between his bite and the use of a bottle during naps and night time. You probably know not to supply him with juice throughout the day as he sucks on a bottle, as this can lead to dental caries.
Your report of the eating difficulties that your child is experiencing also reinforces the speech therapist's recommendation for a neurological examination. A pediatric neurologist is the appropriate resource to not only evaluate your son, but to monitor his subsequent growth and development. I suspect that there is at least some delay in neurological development for speaking and eating. Please know that a neurological developmental delay of the oral structures does not necessarily imply mental retardation. The frustration that your son shows in his attempts to speak could actually be a positive sign that his cortical functions are appropriate. You may be correct that he is apraxic.
A definitive diagnosis may not be possible in a single examination. Don't be surprised if the physician recommends some diagnostic therapy as a way to develop a diagnostic profile on your son over time. Good luck.
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Robert M. Mason, DMD, Ph.D. is a speech-language pathologist (CCC-ASHA Fellow), a dentist, and orthodontist. He is a Past President of the American Cleft Palate-Craniofacial Association, a professional, interdisciplinary organization specializing in problems associated with facial and oral deformities. Dr. Mason has studied and written extensively about orofacial examination, developmental problems related to the tongue, and the anatomy and physiology of the speech and hearing mechanisms. His reports have appeared in speech, dental, medical, and plastic surgical journals and texts. He is considered to be an expert in tongue thrusting, tongue tie, and other problems related to tongue functions and speech.