Australasian Dentist Issue 89

Category 54 AustrAlAsiAn Dentist molars is almost invariably followed by mesial migration of the second molar into the first molar position. this happens regardless of the timing of the extraction. By contrast the extraction of lower first molars is followed by an unpredictable response. While the lower second molar migrates mesially it tips significantly. usually the most favourable drifting occurs when first molar extraction occurs when the bifurcation of the second molar is just forming. Mesial migration is often reduced in deep overbite and low mandibular plane angle patients. Despite these limitations, first permanent molar serial extraction is indicated to provide a reduced restorative experience and lifetime cost for the patient, by substituting healthier teeth in place of compromised teeth. Summary We started by saying that serial extraction may be suitable for 15% of patients. When missing and compromised teeth, and posterior crowding are added to serial extraction indications, then the percentage may increase to between 20 and 25%. the ethnic and genetic mix of the orthodontist’s practice may either increase or decrease this percentage. it is important to recognize that serial extraction requires ongoing assessment of the growing patient at strategic times. For this to be successful, the clinician needs to be one step ahead of the crowding and plan observation/recall appointments appropriately. there is a need to constantly re-evaluate the patient. therefore, a good recall program in conjunction with a well-educated parent and referral source are essential to serial extraction success. When indicated, serial extraction can dramatically decrease the overall severity and time of treatment providing an excellent service for the patient. negligible impact on incisor retraction. in patients with missing premolar teeth, a space closure approach eliminates any future need for prosthetic replacement of the missing premolar, should the retained second primary molar fail. this significantly reduces the overall cost to the patient who experiences 1 or more missing second premolar teeth. A similar modification can be used for Class ii patients with missing second premolars. using Proffit’s camouflage approach of extracting upper first and lower second premolars, the extraction of lower second primary molars which have no successors at age 9, followed by drifting of the teeth frequently results in mesial movement of the lower molar, correcting the molar from Class ii to Class i during lower arch driftodontics. the stage 2 treatment involves upper premolar extraction utilizing this upper extraction space to correct the Class ii to Class i. upper arch anchorage requirements will be determined by the pattern of drift after lower extractions. Missing Incisors the principles for serial extraction still remain, when incisors are congenitally absent. With absent incisors, the clinician needs to pay particular attention to the midline and the anchorage requirements associated with attaining the correct overjet and overbite. sometimes the incisor contralateral to the missing incisor should be extracted in Phase 2 rather than in Phase 1, to allow space for midline and overjet correction. Compromised Teeth Occasionally the patient presents with compromised teeth, suchasheavily restored or extensively decayed first permanent molars. extraction of upper first permanent up to resolve crowding, rather than to retract the incisors. Arch width is not compromised by extractions. Kim and Gianelly demonstrate that smile width is not compromised by extractions. smile widths are the same for extraction and non-extraction cases. Beyond the Basics – Second Premolar Serial Extraction second premolar serial extraction is indicated when there is less crowding which is posteriorly placed, and/or when second premolars are compromised. the clinician can expect significant mesial drift of the molars with significant tipping of the first molars and premolars. this has to be corrected during the Phase 2 braces stage of treatment. in less crowded cases or those with posterior crowding, the second premolar serial extraction will have less impact on incisor positioning and will resolve the problems where they exist, namely the posterior aspect of the arch. Missing Premolars serial extraction of second primary molars is indicated when second premolars are absent, and the malocclusion lends itself to extractions. the clinician needs to assess the amount of crowding, the molar relation and incisor position to determine if space management is needed when the e is extracted. As with second premolar serial extraction, there is significant space closure with mesial drifting of the first permanent molars. this can be helpful in correcting a Class 2 molar when the lower fist molar is allowed to drift forwards into Class 1. Both the first molars and first premolars tip into the e extraction site, which requires correction in Phase 2. the extraction of lower second primary molars encourages mesial drift of the lower permanent molar, with lInICal Case 1