Why should we use it?
o Reduces anchorage demand, entact posterior segments
o Improve dental occlusion in a shorter time frame
o Profile improves in mandibular protrusion cases Levin 1964
When should we use it? Systematic review Zhylich 2011
o Mild-moderate class 3
o Edge to edge anterior occlusion
o Crossbite with mild anterior mandibulae excess
o 4.5mm tooth size discrepancy of lower to upper Matsumoto 2010
When should we not use it?
o Severe OB
o Bimaxillary crowding
o Triangular lower incisor and minimal crowding 3mm less
o High insertion of labial frenum = gingival recession I removed
Risks of lower incisor extraction
o Black triangle
o Increased overjet and overbite
o Tendency for spaces to reopen an aesthetic zone
o Create tooth size discrepancy
Bolton’s anterior analysis
o Anterior ratio 77% 3-3 lower Vs 3-3 upper
Cases:
o Class 1
o 4mm of crowding of the lower incisors
o Bolton’s anterior analysis 87% – excess lower incisor tissue
§ = Extraction 1 lower incisor = 74.8% – TOO LOW (ideal 77%)
· = Solution strip upper 2-2 by 2mm = 78% Bolton’ ratio
o Case 2
o Molars ½ II, increased overjet 6mm, lower incisors 4mm of crowding
o Bolton’s anterior analysis 87% – excess lower incisor tissue
§ = Extraction 1 lower incisor and stripping of upper incisors = 77%
§ = Extraction of 2 upper premolars as well
· Stripping upper 2-2 to achieve ideal occlusion in the anterior 3-3 segment
· Extraction of Upper 4s to correct the increased overjet
References
Zhylich, D. and Suri, S., 2011. Mandibular incisor extraction: a systematic review of an uncommon extraction choice in orthodontic treatment. Journal of Orthodontics, 38(3), pp.185-195.
