Twelve-month space changes after premature loss of a primary maxillary first molar

Background. Many early investigations concerning space changes following premature extraction of primary molars had a cross-sectional design, a small sample size, and a somewhat crude methodology, which may have led to misunderstandings. Aim. The aim of this study was to use established longitudinal data to investigate ongoing (12-month) dental-arch space problems arising as a result of premature loss of a primary maxillary first molar. Design. Thirteen children (mean±SD age at time of tooth extraction, 6.0±0.74years) with unilateral premature loss of a primary maxillary first molar were selected for this study. Maxillary dental study casts were obtained from participants 2 or 3days after the tooth was removed, as well as at a follow-up appointment 12months later. Six reference lines were measured on the study cast: D+E space, arch width, arch length, intercanine width, intercanine length, and arch perimeter. For each participant, the D+E space of the contralateral intact primary molar served as a control. A paired t-test was used to compare the cast measurements between initial examination and 12-month follow-up. A t-test was used to compare D+E space changes with those of the control group. Results. The D+E space of the extraction side after 12months was significantly smaller than that of the control side (P<0.05) and the initial D+E space (P<0.05). A significantly greater arch perimeter, intercanine width, and intercanine length were found after 12months compared with the initial parameters. No significant differences were found, however, in arch width or arch length between the initial examination and the 12-month follow-up examination (P>0.05). Conclusions. The 12-month space changes in the maxillary dental arch after premature loss of a primary maxillary first molar consist mainly of distal drift of the primary canine toward the extraction site. Mesial movement of permanent molars or tilting of the primary molars did not occur. An increased arch dimension was found especially in the anterior segment (intercanine width and length). There is no need for the use of space maintainers from the results in this study in cases of premature loss of a primary first molar.