Mandibular changes secondary to serial extractions compared with late premolar extractions and controls

Mandibular dental changes following serial and late extraction of mandibular second premolars

“…When mandibular second premolars, or deciduous mandibular second molars without successors, were extracted early, there was no significant difference in final mandibular incisor inclination compared with delaying extraction until the full permanent dentition. To summarize the important findings comparing serial extraction of mandibular 5's or E's versus mandibular 4's serial extraction 16 : there was less lingual tipping of mandibular incisors, similar tipping of canines, and more mesial tipping of first molars following physiologic drift when 5's or E's were extracted. 16,25 These results confirmed Logan's 26 findings that second premolar extraction reduced excessive lingual movement of mandibular incisors and prevented the ''concaving'' of the lower face.…”

“…To measure the occlusal curves, stone dental models were scanned using a computer program, Ortho Insight 3D (version 4.0; MotionView Software, Chattanooga, TN), into .stl digital files that were then opened in a separate computer program, Rhinoceros (version 5.0; Robert McNeel & Associates, Seattle, WA), to create best-fit spheres that were placed on the models, and the resulting radii were measured. 16 The sphere radii corresponded to the depth of the occlusal curvatures: the steeper the curvature, the smaller the radius. Three separate spheres were produced ( Figure 1) according to the following landmarks: the curve of Spee: MB and DB cusps of mandibular first molars and incisal edges of the four mandibular incisors; the curve of Wilson: MB, ML, DB, and DL cusps of the mandibular first molars; and Monson's spheres: MB, ML, DB, and DL cusps of the mandibular first molars and incisal edges of the four mandibular incisors.…”

“…Three separate spheres were produced ( Figure 1) according to the following landmarks: the curve of Spee: MB and DB cusps of mandibular first molars and incisal edges of the four mandibular incisors; the curve of Wilson: MB, ML, DB, and DL cusps of the mandibular first molars; and Monson's spheres: MB, ML, DB, and DL cusps of the mandibular first molars and incisal edges of the four mandibular incisors. 16 Cephalometric radiographs were scanned to create digital copies, and using Rhinceros 3D, vertical lines were digitally drawn through the long axes of the mandibular first molars, first premolars, canines, and central incisors, and the angle relative to the palatal plane was measured. The palatal plane (ANS-PNS) was the chosen reference plane as it could be located precisely and was easily reproducible; it is located close to the areas under consideration and experiences minimal change over time compared with other possible reference planes such as the mandibular plane or Sella-Nasion.…”

“…The palatal plane (ANS-PNS) was the chosen reference plane as it could be located precisely and was easily reproducible; it is located close to the areas under consideration and experiences minimal change over time compared with other possible reference planes such as the mandibular plane or Sella-Nasion. 23,24 The palatal plane was also used in previous, separate studies by Yoshihara et al 25 and Feldman et al, 16 both of whom noted that there was no influence of growth changes at Nasion, there was no influence of rotation of the jaws, and the inclination of the occlusal plane by dental effects was excluded.…”

“…8,[10][11]13 Other disadvantages of serial extractions include deepening the overbite, lingual tipping of incisors, distal tipping of mandibular canines, mesial tipping of molars, creation of a diastema and increased spacing, potential scar tissue buildup in the area of the extraction sites, and alteration of tongue function. 2,[14][15][16] Modified serial extraction occurs when deciduous second molars and/or second premolars are extracted rather than deciduous first molars and first premolars. 17 Second premolar serial extraction advantages compared with first premolars can then be listed as (1) better root parallelism and marginal ridge contact, (2) limited lingual migration of mandibular anterior teeth, (3) minimal increase in the curve of Spee and overbite, (4) minimal flattening of the facial profile, and (5) increased bodily drift of the first and second molars, which can aid in class II molar correction.…”