Geometric distortion of panoramic reconstruction in third molar tilting assessments: a comprehensive evaluation.

OBJECTIVES:: To evaluate the geometric distortion of tilting of mandibular third molars with respect to second molars on panoramic reconstruction. METHODS:: Cone-beam CT (CBCT) reconstructions of 160 third molars, obtained due to an indication of risk of inferior alveolar nerve damage during surgery, were used. CBCT-reconstructed panoramic images were used as bi-dimensional (2D) images, to avoid distortions other than geometric distortions. The angle between the second and the third molar was measured in 2D and three-dimensional (3D) images. Student's t-test was used to assess the null-hypothesis of no difference between 2D and 3D measurements. RESULTS:: A significant mean difference (-2.3° ± 6.3°) between 2D and 3D measurements was found, with an absolute error of 3.6° ± 5.7° and a relative error of 10%. These findings comprehensively explain the geometric distortion on panoramic radiographs. CONCLUSIONS:: Although a widely used and undoubtedly useful tool for diagnosis and surgical planning of mandibular third molar extractions, panoramic reconstruction are biased from geometric distortion that may influence surgical planning.

Rehabilitation with implant-retained removable dentures and its effects on perioral aesthetics: a prospective cohort study.

BACKGROUND: The onset of perioral wrinkles often prompts patients to request treatment. This aesthetic deterioration linked to aging may be associated with tooth and alveolar bone loss in fully edentulous patients. PURPOSE: To evaluate perioral wrinkles before and after maxillary and mandibular rehabilitation with implant-retained dentures in fully edentulous patients. METHODS: In this prospective cohort, single-center, blinded study, patients requiring maxillary and mandibular rehabilitation with implant-retained dentures were enrolled. The patients were photographed in the same position before and after oral rehabilitation. Wrinkles were evaluated in the photographs by blinded observers using validated rating scales. The following parameters were analyzed: upper and lower radial lip lines, marionette lines, upper and lower lip fullness, nasolabial folds, corner of the mouth lines, and the labiomental crease. Statistical analysis was performed using the Wilcoxon signed ranks test for paired data, with P<0.05 considered significant. RESULTS: Upper and lower implant-retained dentures were applied in 31 patients (15 males; mean ± standard deviation age 62.13±8.69 years, range 47-77 years). The oral rehabilitation procedures significantly improved (P<0.05) the upper and lower radial lip lines, marionette lines, upper and lower lip fullness, the nasolabial folds, and the corner of the mouth lines. CONCLUSION: Maxillary and mandibular rehabilitation with implant-retained dentures in fully edentulous patients improves perioral aesthetics. Patients requiring oral rehabilitation and desiring perioral aesthetic improvement could benefit from treatment with this type of prosthesis.