This is a cross-sectional study that aimed to estimate maxillary sinus floor (MSF) pneumatization in single missing tooth of posterior maxilla, by using cone-beam computed tomography (CBCT). CBCT images were analyzed bilaterally and divided into 2 groups: edentulous site (EdS) - edentulous single region of upper second premolar, first or second molars; Tooth site (TS) - contralateral region homologous to the EdS region, with tooth present. Variables evaluated were: sinus height (SH), estimated sinus pneumatization (eSP: ∆ EdS - TS), healed ridge height (HR) and presence of localized sinus pneumatization (LSP) in molars teeth at TS. HR were categorized according to therapeutic option for posterior maxilla. 183 CBCT scans were included and it was observed that EdS presented a higher SH than the TS (p < 0.001) showing an eSP of 0.9 ± 2.93 mm. First molars presented the highest SH for both sides, although significant differences were detected when compared to second molars. First molars were mostly affected by LSP at TS (36 out of 43). Individuals with LSP at TS presented lower HR than the ones without LSP (p < 0.05). 54% of the cases presenting LSP obtained HR < 5 mm, which indicates sinus lift surgery. The present study showed that tooth loss in posterior maxilla favors sinus pneumatization and the identification of LSP at molar roots seems to indicate a greater necessity for sinus lift surgeries.