THE DENTIST ADVISES
Dr. BERTRAND R. STUART DDS.
It is necessary to understand the critical processes occurring during the development of the face, oral cavity and jaws in the embryo ( growing organism in the womb up to 8 weeks) and the foetus (from 8 weeks to birth) if we are to comprehend certain manifestations of conditions that stem from that development. The most notable conditions are cleft lip and palate which incidentally for some unknown reason are seen mostly in this country in children of East Indian parents.
At approximately Week 4 in the womb, the embryo begins to develop five facial projections, which eventually form the face, oral cavity, palate and jaws. The frontonasal projection forms the forehead, nose, and philtrum (groove in the upper lip). The maxillary process (2 projections) forms the middle face and upper lip, while the mandibular process (2 projections) forms the mandible (lower jaw) and lower lip.
At Week 5 the frontonasal and maxillary processes begin to form the nose and maxilla (upper jaw). However, if the nasal and maxillary processes fail to fuse a cleft lip and palate will result. A cleft lip can be anything from a small notch in the lip (incomplete cleft) to a wide gap that runs up to the nostril (complete cleft lip). One type of cleft palate (submucous) can be hidden. There are two types of cleft lip: unilateral which appears on one side of the lip at the philtrum and bilateral which occurs on both sides of the lip, both sides of the philtrum. By Week 6, the primary palate and nasal septum (which divides the nasal cavity into two) have developed.
The development of the jaws (mandible and maxilla) starts at Week 6 whereby a band of dense fibrous tissue called Meckel’s cartilage forms which provides the structure around which the mandible develops. By Week 7, bone develops, outlining the body of the mandible, as the bone grows backwards two secondary cartilages form; these eventually become the heads and necks of the lower jaw bone. As the bone grows forward, the two sides are separated by a cartilage called the mandibular symphysis. The two sides will finally fuse into one bone approximately 2 years after birth. Upward growth of bone begins along the mandibular arch forming the alveolar process on which the teeth will develop.
By Week 8, ossification ( bone development) of the maxilla begins. Known as the tooth germ, the bud formation begins as a clump of cells in swellings called enamel organs. Each enamel organ is responsible for the development of a tooth. The enamel organ continues to grow and by 12 weeks there is differentiation of the cells into four tissues layers of the tooth recognisable by the fourteenth week.
Many factors can influence the outcome of the health of the oral cavity whose main functions are digestion (production of saliva), biting, chewing, swallowing and speaking. These include genetics, medications, disease of the mother and bad habits. The baby teeth are 20 and first appear from the age of 6 months and the last being 30 months. Parents and guardians should take their baby for a routine dental checkup to prevent future problems and/or correct those present.