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News Bulletin : ADA News Bulletin August 2011
37 AUGUST 2011 It can clearly be seen that lower lateral incisors are positioned lingually even before eruption (Fig 2) and so it is understandable for them to be positioned lingually on eruption and that it is not a sign of crowding. In the same way, the mandibular angle of a child is normally obtuse and it is definitely not a sign of deformity needing surgical correction. Right up to the late 1950s, many young children were diagnosed to have ‘thymic hypertrophy’ and were subjected to radiation in order to shrink the thymus gland. The authorities then believed the large thymus is abnormal and is interfering with breathing. They didn’t realise that it is normal for the thymus gland to be large in children and it decreases in size with age. It was not until 1961 when Dr Jacques Miller, the modern ‘father’ of Immunology (Melbourne University) discovered that the thymus gland was crucial to the immune system (T-cells). It is often said that Dr Miller deserved the Nobel Prize. It would be interesting to find out what happened to the immune systems of those individuals whose thymus glands were subjected to radiation and whether they maintained good health. It is anatomically correct for lower lateral incisors to be positioned lingually in the early mixed dentition stage (KP Lee; Behaviour of Crowded Lower Incisors. JCO, Jan. 1980). The extraction of primary cuspids to correct crowding is obviously based on a wrong diagnosis. Joseph Fox wrote: “In any of these discrepancy cases the removal of the primary cuspids is absolutely necessary, and unless the operation be timely performed, the irregularity is with difficulty remedied.” Some other authorities believe that if crowding is not corrected early, the incidence of relapse is much greater. Such beliefs are still being promoted even though they are not evidence based. Infants born prematurely are more likely to have under- developed internal organs, such as lungs. Isn’t it possible that premature extractions of primary cuspids could also result in under developed dental alveolar arches? What will happen if primary cuspids are not removed when lower lateral incisors are positioned lingually? Case GB (Fig 3) clearly shows lower lateral incisors positioned lingually in the mixed dentition stage. The primary cuspids were not extracted and the four incisors improved in alignment autonomously, not needing any orthodontic treatment of any kind. So, this clearly disproves what Joseph Fox said. What would have happened if the primary cuspids were extracted? More than likely, the first premolars would have had to be extracted to accommodate the crowded permanent cuspids. It can be said that the practice of premature extractions of primary cuspids is counterproductive. Fig 3. Case GB 15/5/1979 11/1/1988 “Children are not miniature adults – they are different. dental crowding depends greatly on growth/ development and since growth prediction is far from being exact, wouldn’t it be wiser... instead [to] try prescribing ‘tincture of time’.” opinion page The belief that if crowding is not corrected early, the incidence of relapse will be greater is not backed up by evidence. If no orthodontic treatment was carried out, and if there is subsequent movement of the teeth, can the clinician be responsible for the ‘relapse’? Children are not miniature adults – they are different. Dental crowding depends greatly on growth/development and since growth prediction is far from being exact, wouldn’t it be wiser not to pick up the extraction forceps but instead try prescribing ‘tincture of time’. In dealing with young children when the dentition is still in the active growing/developing stage, it is better to be sure that you are unsure than to be plain yes or no. The most basic creed of the health service canon – ‘First do no harm’ (Hippocrates). “Let the eye go before the hand, and the mind before the eye” (Oliver Wendell Holmes) K Paul Lee South Perth 6151
ADA News Bulletin July 2011
ADA News Bulletin September 2011