Moyers, RE, Handbook of Orthodontics, 3rd Edition, Chicago, Yearbook Med. Publications
Mixed Dentition Analysis: based on the determination that there is a high degree of predictability of tooth size between groups of teeth, Moyers developed a way of forecasting the space needs for the eventual eruption of the permanent teeth as early as seven years of age.
Northway WM, Wainright RL, Demirjian A.
Effects of premature loss of deciduous molars. Angle Orthod. 1984 Oct;54(4):295-329.
A statistical exploration of space changes following early loss of deciduous molars, developing a picture of closure from both directions with district differences between upper and lower arch changes. No matter which of the primary molar is removed is removed more than a year early, there will be a reduction of arch length of about one millimeter per year, cumulative.
Northway WM, Wainright RW.
D E space–a realistic measure of changes in arch morphology: space loss due to unattended caries. J Dent Res. 1980 Oct;59(10):1577-80.
By using only a portion of the dental arch, rather than some geometric construction that conforms to the dental arch, more pertinent information can be gathered regarding the sequelae of some event or insult to the arch. The measurement, D E Space, has been explained and utilized to describe the effects of unattended dental caries on arch form. Only caries which become severe have a significant effect on the dental arch–a reduction in D E Space, which can be interpreted as relative arch length (depth) and is significant only for the year after its exfoliation. This occurs one year early and is also significant.
Northway WM.
The not-so-harmless maxillary primary first molar extraction. J Am Dent Assoc. 2000 Dec;131(12):1711-20.
BACKGROUND: Premature loss of primary molars has been associated with space loss and eruptive difficulties, especially when the loss occurs to the primary second molars and when it occurs early. This has not been thought to be the case for primary first molars. METHODS: The author revisited 13 cases from an earlier study on the effects of premature loss of maxillary primary molars. These longitudinal cases were scrutinized, using serial panoramic radiographs, to explain the irregular response in terms of dental migration. The author presents two case reports. RESULTS: In the earlier study, the author used digitized study casts and the concept of D + E space–the space occupied by the primary first and second molars–to describe the dental migration that occurred after premature tooth loss. Using analysis of variance on data generated using an instrument capable of measuring in tenths of millimeters, the author produced findings regarding the amount of space loss, rate of space loss, effect of age at loss, amount of space regained at the time of replacement by the permanent tooth and effect on Angle’s classification. Finally, the author created a simulation describing directional change; this revealed that the maxillary primary first molar loss resulted in a mesial displacement of the permanent canine during eruption. CONCLUSIONS: When the maxillary primary first molar is lost prematurely, the first premolar erupts in a more mesial direction than normal, as a result of the mesial incline of the primary second molar, and consumes the space of the permanent canine, which becomes blocked out. CLINICAL IMPLICATIONS: Rather than use a space maintainer after the premature loss of the maxillary primary first molar, the author suggests, clinicians can choose from a number of other options for preventing the first premolar from erupting too far in a mesial direction.
Northway Orthodontics