Biogenesis of the Successional Dentition 10/2/09

Resident: MurphyDate: 10/1/09
Article title: Biogenesis of the Successional Dentition
Author(s): Baume, Louis. Journal: J.D. Res, Vol 29, #3. 1949
Major topic: Comparing space accommodation between the deciduous and succedaneous dentition

Type of Article: Analysis
Findings: The maxillary and mandibular incisors are each wider than their deciduous predecessors. In order to accommodate these larger teeth, a physiological expansion of the arches is necessary. This sagital and tranverse expansion takes place between the ages of four and six. This study focuses on the changes which affect the dental arches during and after the eruption of the permanent incisors. 60 study casts where studied and labeled as stage 1, deciduous dentition completed, stage 2, perm. 1st incisors have erupted, and stage 3, all perm incisors are in. The cases were also separated by ebeing closed spacing cases, or open spacing cases. Measurements were taken between the deciduous canines and second molars at the gingival margin. As previous studies show, the eruption of the perm. Incisors presented a transverse widening of the mandibular arch of approx. 2.3mm(sd 5mm). This widening is due to lateral growth of the alveolar process, not necessarily to adjacent teeth being displaced. The maxilla also shows widening, although due to different reasons. These reasons being the eruption sequence (max. incrs erupting after man. Incrs.), and the second being differences in maxillary primate spaces. The breakdown of the numbers between all the different stages and case types was dizzying. The minimum increase in mandibular canine expansion was represented by the stage 1 and 2, type 1, with .5mm, and the largest being stage 3 type 2, with 5 mm. Again, the numbers are confusing. The bets thing to do is just take a look at the tables provided. Conclusions: Essentially, expansion of both arches in the anterior region is brought about by frontal and lateral growth to accommodate the larger succ. Teeth. There was greater increase in intercanine width and forward extension(1mm) of the arch in the max. as opposed to the mand., and greater increase associated with closed cases as opposed to open space cases. The strongest lateral growth of the mand. Arch was associated with the eruption of the mand 2nd incrs, and during the eruption of the perm max incrs. As previously noted, the ‘secondary’ spacing of the maxilla occurred when the underdeveloped maxillary arch widened during the eruption of the perm lower incisors. In terms of comparing spacing cases with closed cases, the spacing cases showed a more favorable alignment. 40% of the closed spaced had anterior crowding.
Assessment of article: I think this was a clinically relevant article that is absolutely worth reviewing. With that said….it was near impossible to read and try to process all the different numbers and stages and cases they were reviewing. The writing is clearly outdated (written in ’49) and fairly convoluted. Bascially try to understand the concepts, take a look at the tables, and move on.

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