Purpose: The objectives of this study were to investigate the prevalence and characteristics of tooth agenesis and the associated skeletal morphology and arch widths in a group of Turkish patients seeking orthodontic treatment. Material and Methods: We designed a retrospective study composed of pre-and post-treatment panoramic radiographs and lateral cephalometric films of 3,341 patients (2,040 females and 1,301 males). Tooth agenesis was evaluated for hypodontia and oligodontia -excluding the third molars-from the orthopantomograms. The significance test for the differences in the skeletal morphology between hypodontia and non-hypodontia patients was performed using the Pearson chi-square and Student t-test. Results: The prevalence of tooth agenesis was 4.6 percent for the Turkish orthodontic patient population. Tooth agenesis was found more frequently in females than in males, although this difference was not statistically significant (p>0.05). The most commonly missing teeth were the maxillary lateral incisors, followed by the mandibular second premolars and mandibular central incisors. Intercanine and intermolar widths in the maxillary and mandibular arches were significantly reduced in the hypodontia group compared with the control group (p<0.01). Tooth agenesis was statistically and significantly less in patients with skeletal Class II (p<0.01). There was no statistically significant difference in hypodontia patients in the vertical relationship of the jaws (p>0.05). Conclusions: The prevalence of tooth agenesis was found to be 4.6 percent for the Turkish orthodontic patient population (hypodontia 4.3% and oligodontia 0.3%), and was found more frequently in females. Intercanine and intermolar widths were significantly reduced in the hypodontia group for both jaws compared with the control group.

Objective: The aims of this study were to investigate the frequency and characteristics of dental transpositions and to evaluate associated dental anomalies in a large sample of Turkish Anatolian population. Study design: A retrospective study was performed using panoramic radiographs of 6983 patients (4092 females and 2891 males) ranging in age from 12 to 27 subjected to Faculty of Dentistry at the University of Ataturk (Erzurum, Turkey) between 2005 and 2008. For each patient with tooth transposition we recorded the demographic variables (including age, sex), history of trauma, type, classification, and location of tooth transpositions, and associated dental anomalies. The Pearson chi-squared test was used to determine potential differences in the distribution of tooth transposition when stratified by gender. Results: Tooth transposition was detected in 19 subjects (0.27%), with a 2.2:1 female male ratio (P= 0.38). The most commonly observed transposition was maxillary canine-lateral incisor (60%). The frequencies of complete and incomplete transpositions were equal (10/10) and it was more common in the left side than in the right side (11/9). Of the 19 subjects, 10.5% had a peg shaped lateral incisor, 21.1% one congenitally missing tooth excluding third molar. Supernumerary tooth, impacted teeth excluding third molars, transmigrated tooth, and dilacerations were also observed. Conclusion: The frequency of tooth transposition was 0.27% in a Turkish Anatolian population and maxillary canine-lateral incisor was the most frequently observed transposition. Retained primary teeth were the most frequently observed dental anomaly in all types of tooth transposition.