The aim of the present study was to investigate the erosive tooth wear of primary and permanent teeth and its association with related risk factors. Two groups of Greek children aged 8 (n = 329) and 14 years (n = 263) were examined in the classroom using the Basic Erosive Wear Examination (BEWE) index. Data concerning risk factors were collected using questionnaires. Dental caries (DMFS/dmfs) was also recorded. The data were analyzed using the t test, one-way ANOVA, multiple regression analysis, Fisher's exact test, and the X2 test. In the 8-year-olds, the primary teeth showed a predominantly medium level of wear and the permanent teeth no wear. A majority of the 14-year-olds exhibited low risk levels of wear. The most frequently affected dental surface in both age groups was the occlusal surface of the mandibular posterior teeth. In the 8-year-olds, BEWE scores and the prevalence of wear in the primary teeth was influenced by gender (p = 0.020). In their permanent teeth, soft drink consumption (p < 0.0001) and preference for lemon/vinegar (p = 0.041) significantly affected wear prevalence and BEWE scores, while habitually retaining soft drinks in the mouth influenced wear prevalence (p = 0.008), risk (p = 0.004), and BEWE scores (p = 0.022). In the 14-year-olds, wear prevalence was significantly affected by the consumption of lemon-flavored candies (p = 0.016) and soft drinks (p = 0.050). BEWE scores were significantly affected by gender (p = 0.022) and soft drink consumption (p = 0.030). Gender influenced tooth wear risk in both age groups (p = 0.010 and p = 0.021, respectively). The results of this study indicate that erosive tooth wear differed between primary and permanent teeth and was influenced by gender and dietary factors.