Cleft disorders originate as a malfunction during the embryonic development of the middle part of the face. Endogenous causes, mainly the heredity at about 10-25% of cases, play a role at their etiology. Among exogenous factors there are mother’s infectious diseases (rubeola, influenza), hormonal preparations, mechanical and chemical influences, lack of vitamin B, excess of vitamin A, various drugs, irradiation, alcohol, nicotine, eventually other teratogenic compounds that act during the period of the face development (5.-12. week of intrauterine life). The most common are clefts of the lips and the palate. Their incidence rate increases during last several decades - there is one cleft disorder per 400-500 of births at present. The cleft disorders classification stems from the process of embryonic development of the oro-facial system. It can be divided into three groups, according to Kernahan and Stark:
1. Primary palate clefts, i.e. clefts of the lip, vestibule and the upper jaw alveolar ridge, up to foramen incissivum. The primary palate is formed during the 5th - 8th week of gestation by connection of the maxillar projection of the first gill slit and the medial nasal projection. The cleft may be either sub-mucous or total. It sometimes affects the lip’s red only, or the whole lip and the alveolar ridge. In case of the alveolar ridge affection, irregularities in the teeth position, number and shape occur as well. If the cleft reaches the nose bottom part, it causes its deformation. In case of the total one-sided cleft of the lip and alveolar ridge up to foramen incissivum, the larger segment together with the premaxilla are tilted forwards, the smaller segment is reduced at all dimensions. In case of a double-sided cleft, the premaxilla is connected to the vomer and often skewed in forward and upward directions. Defects of the nose are present to a various extent.
2. Secondary palate clefts originate at the 8th-12th week of gestation. During this period, the tongue which had filled the combined oral and nasal cavities so far, got lowered and lateral palatal projections get connected thus dividing the nasal cavity from the oral cavity at the area behind the primary palate. If the connection does not take place, the isolated palatal cleft occurs. It can range from an isolated cleft of the uvula, through the cleft or shortening of the soft palate, to the total palatal cleft up to foramen incissivum. The sub-mucous palatal cleft distorts the continuity of muscles or even the bone, the mucous cover is preserved, though. The alveolar ridges and the dental arch is formed normally.
3. Primary and secondary palates clefts affect the lips, the alveolar ridge, the hard palate, the soft palate and the uvula. They may be either single-sided or bilateral. A single-sided, complete cleft divides the above listed formations into two unequal parts: the bigger part containing the inter-maxilla and connected to the vomer and septum nasi; the smaller part is formed by the remains of lips, the alveolar ridge and the palate. The mutual bearing of the segments is usually damaged. In cases of bilateral total clefts, the premaxilla is joined to the vomer and the septum nasi form an independent part that protrudes at the anterior direction in front of side segments, or it is interlaced between them at the oral direction. Parts of hard and soft palates are not connected at the middle line.
4. Facial clefts are rarely occurring disorders which originate during the embryonic development, too. Middle clefts affect the nose, upper and lower lips, eventually the lower jaw. Oblique clefts go from a nose wing to the inner eye corner. Cross clefts are localized at the oral fissure area and manifestate as macrostoma.
Functional defects at cleft disorders.
Functions of the oro-facial system are hampered to the greatest extent at clefts of the third group. Due to oro-nasal communication, the nursing, swallowing and breathing are affected. Nasal mucosa, airways and the middle ear often suffer from inflammations. Children of later ages have speech problems.
Cleft disorders therapy.
Children affected with cleft disorders have to be under a follow-up care from the birth to adult age. Therapy is very demanding and takes place at centers for cleft disorders that are being established at plastic surgery clinics. Therapy is conducted by a team of experts who determine an individual plan of cure and a schedule for individual phases of therapy. Since it is necessary to ensure feeding at nurslings, the oro-nasal communication is closed by the palatal plate. The ventral shift of inter-maxilla is corrected by an elastic band, connected to a cap. Clefts of the first group undergo a surgery at the age of 5-8 months. Reconstruction of a lip, vestibule and the nose bottom takes place during this surgery. The hard and soft palates closure is performed at the age of 3-4 years, i.e. the period when the temporary dentition is completely cut. The aim of the palatal plastic surgery is dividing the oral cavity from the nasal cavity. The goal is that operation scars do not slow down the jaws’ growth too much and that the growth centers can be employed as much as possible. A patient undergoes the orthodontic therapy from his/her birth to the completion of the permanent teeth development. The aim of this cure is to support the growth and development of jaws of an affected individual. It also creates conditions for an optimal surgical treatment of clefts, reduces adverse effects of scars on the skeleton growth at the period after a surgery with help of an active therapy, shielding therapy, or myotherapy. Positive conditions are also formed by correction of the teeth position, shapes of the dental arches and alignment of the jaws, that serve for a definite sanation of the teeth at later age. The prosthetic therapy should guarantee a functional and esthetic rehabilitation of the teeth at these patients.