Twenty-eight (23%) presented agenesis of other teeth, whilst agenesis of other dental groups plus third molar was present in 25 (21%). Four patients

had oligodontia (at least six teeth missing). GSK126 chemical structure Fig. 1 illustrates the dental agenesis distribution by tooth considering the whole dentition. As indicated, third molar is the most common missing tooth (14%), followed by premolar (2%) and incisor (1%), whereas the occurrence of canine and other molar ageneses is much less frequent (0.3% and 0.9%, respectively). Comparisons between left and right quadrants, or upper and lower arches agenesis showed no significant statistical differences. Females presented more tooth agenesis than males when only upper teeth were considered (9, 10, 11, 12, 13, 14, 15, 16, 8, 7, 6, 5, 4, 3, 2, 1 teeth; Fisher’s exact test p-value = 0.037). However, removing the upper third molars (18 and 28 teeth) of the analysis, the significance is lost (p-value = 0.064). A significant value between genders

was also obtained when all incisors were compared (9, 10, 8, 7, 25, 26, 24, 23 teeth; Fisher’s exact test p-value = 0.022) (data not shown). Whites presented more tooth agenesis than Blacks when the upper teeth, left and right quadrant, http://www.selleckchem.com/products/abt-199.html as well as molar dental groups were considered separately. However, the significance of these differences is lost (with exception of the right quadrant) when third molars are excluded from the analysis (Table S2). Third molar agenesis frequency differences are expected, since it is well known that third molar absence is rare in Sub-Saharan Africans as compared to Europeans.11, 12, 13, 14, 15, 16, 17, 18, 19, 20 and 21 Sequences of the

DNA binding domain and of other regions of the MSX1 and PAX9 genes were obtained for 35 patients with distinct tooth agenesis and respective controls ( Table 2). The following PAX9 and MSX1 nucleotide sequences were submitted to GenBank, IDs: HM213907–HM214140. No mutation was found in PAX9 exons 2 and 4. Sequencing revealed, however, six nucleotide substitutions outside the DNA binding domains of both genes (PAX9 exon 3: rs12881240, rs4904210; 5′ flanking intronic segment of PAX9 exon 3: rs7143727; untranslated region of MSX1 Lck exon 2: rs8670, rs1095, rs12532), all recognized as single-nucleotide polymorphisms in the available databases ( Table 2). There is no statistical difference between allele and genotype distributions in patients and controls (Table 3). Kim et al.27 and Nieminen7 suggested that MSX1 and PAX9 differ in their influence for agenesis of specific teeth. Both genes affect third molars, but significantly higher frequencies of agenesis for second premolars and maxillary first premolars were found in association with MSX1 mutations as compared to PAX9 mutations. Whilst, agenesis of the maxillary first and second molars and mandibular second molars was significantly more common in association with PAX9 nucleotide substitutions.