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Abstract
To assess space changes in the dental arch following premature extraction of the first primary lower molar in 7-9 years children. The study consisted of 48 children in the age group of 7 - 9 years old who attended pediatric dentistry department Faculty of oral and dental medicine Cairo university and underwent premature extraction of primary mandibular first molar. Clinical and radiographic examinations were performed to confirm the indication of first primary molar extraction. The degree of successor root development was assessed according to Nolla{u2019}s system with the aid of radiographic images. Impressions were taken immediately before the extraction and initial casts were poured. All patients had recall appointments every 2 months and longitudinally, the procedure of impression taking and cast preparing was repeated at each follow-up at two, four, six and eight months after extraction. Thus each patient was subjected to clinical evaluation at five stages. Measurements on the casts including arch length, arch perimeter, inter-molar width, inter canine width and (D + E) Space were performed to assess space changes initially before extraction and at each follow up interval. Any needed dental treatment was delivered to our patients. The (D + E) space was decreased by (0.64 ± 0.59) at the end of follow-up period which was considered statically significant (P = 0.001). However, the clinical significance of such a value is questionable. The arch length, arch width and arch perimeter showed a statistically insignificant difference between the initial examination and the 8 month follow up examination (P = 1). An inverse relationship was found between the amount of space loss at the end of follow up period and degree of successor{u2019}s root development according to Nolla{u2019}s system