Australasian Dentist Issue 89

Category 52 AustrAlAsiAn Dentist The Basics serial extraction is a viable option for those patients that have 10m mm or more of crowding, with a Class i occlusion, a minimal overbite or an open bite, and a protrusive dentition relative to the face. Approximately 15% of the population are suitable for serial extraction. the serial extraction procedure classically involves the extractions of primary canines as the lateral incisors are erupting. this allows the crowded permanent central and lateral incisors to spontaneously improve their alignment. then at approximately age 9 to 10, first primary molars are extracted. the purpose of this procedure is to accelerate the eruption of the first premolar teeth. When one considers that the normal eruption sequence in the upper arch involves the eruption of first premolars before the canines, the extraction of upper primary first molars is often not needed. By contrast in the lower arch, 50% of the time the first premolars erupt before the canines and the other 50% of the time the lower canines erupt before the first premolars. the goal of treatment is to have the first premolars erupt ahead of the canines so they can be extracted early to allow the canines to erupt distally. therefore, in the lower arch when the eruption sequence is unfavourable, then the extraction of lower first primary molars is suitable to facilitate or accelerate the eruption of the first premolars. the first premolars are then extracted upon eruption usually at age 11 to 12 and there is a period of what is commonly called driftodontics. Driftodontics is the natural movement of teeth into the extraction space, and often significantly improves alignment and makes future active orthodontic treatment easier and shorter. When all permanent teeth are fully erupted, the patient would have comprehensive treatment to detail the alignment, close residual extraction spaces and parallel the roots. severely bimaxillary protrusive patients who require maximum retraction of incisors are not suitable candidates for serial extraction. When serial extraction is performed with the initial removal of the deciduous canines, the lower incisors tend to spontaneously improve their alignment. in a longitudinal study by Yoshihara, there was a 6mm improvement in the irregularity index after lower primary canines and lower first premolars were extracted. there is continuing improvement in incisor alignment after the extraction of the first premolars, but to a much lesser extent. One modification that needs to be considered for serial extraction is whether premolars should be enucleated rather than extracted upon eruption. it is particularly indicated when the permanent canine is erupting ahead of the first premolar. some children are apprehensive about extractions and as a result, the extractions of primary canines followed by first primary molars, followed by premolars extractions becomes an adverse behavioural issue for needle phobic children. For such children, the enucleation of premolar teeth, that is extraction of the first primary molars and simultaneous extraction of the unerupted Serial Extraction – Should it still be performed? By Geoffrey Hall Figure 1 The traditional serial extraction approach lInICal Dr Geoff Hall