Eruption rates of lower second premolars at different development stages evaluated with cone-beam computed tomography.
OBJECTIVE
To evaluate and compare the eruption rates of lower second premolars (LPm2) at different developmental stages using cone-beam computed tomography (CBCT).


METHODS
Retrospectively, 31 individuals (9.77 ± 1.25 years) had their LPm2 scored according to the Demirjian method, and afterwards they were split into three groups according to developmental stage, as follows: D = complete-formed crowns; E = root length less than crown height; and F = root length greater than or equal to crown height. Linear distances from the LPm2 crown tip to the anatomical reference line (ARL) and to the occlusal plane line (OPL) were measured in paired CBCT scans (T1, T2), taken with an average interval of 8.6 months between them. Eruption rates (mm/y) were calculated and then compared between groups.


RESULTS
Eruption rates were greater for LPm2 at stage F than at stages D or E (P < .01) regardless of whether they were measured from the ARL (D = 2.84 mm/y; E = 2.55 mm/y; F = 5.38 mm/y) or from the OPL (D = 1.82 mm/y; E = 2.02 mm/y; F = 5.26 mm/y). Eruption rates evaluated from the ARL and the OPL had no statistically significant differences (P = .052), and a positive correlation (r = .79, P < .001) between them was observed.


CONCLUSIONS
LPm2 at Demirjian stage F showed greater eruption rates than at stages D or E, regardless of whether rates were measured from the ARL or the OPL. Faster eruption is expected for LPm2 at stage F. Evaluation of the LPm2's developmental stage using CBCT can aid in clinical decision making regarding the correct timing for intervention.
Mariana Roennau Lemos
MRL
Rinaldi
Eduardo Martinelli
EM
de Lima
Luciane Macedo
LM
de Menezes
Susana Maria Deon
SMD
Rizzatto
Paulo Ricardo Baccarin
PRB
Matje
Roberto Vanin Pinto
RVP
Ribeiro
D001641:Bicuspid / Q000000981:diagnostic imaging* / Q000254:growth & development*; D002648:Child; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D012189:Retrospective Studies; D019228:Tooth Crown / Q000000981:diagnostic imaging / Q000254:growth & development; D014078:Tooth Eruption
Cone-beam computed tomography; Premolars; Tooth development; Tooth eruption
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