Three-dimensional evaluation of the correlation between lip canting and craniofacial planes.

OBJECTIVE: This study aimed to analyze the correlation of horizontal and sagittal planes used in two-dimensional diagnosis with lip canting by using threedimensional (3D) analysis. METHODS: Fifty-two patients (25 men, 27 women; average age: 24 years) undergoing treatment for dentofacial deformity were enrolled. Computed tomography images were acquired, and digital imaging and communication in medicine files were reconstructed into a 3D virtual model wherein horizontal and sagittal craniofacial planes were measured. Subsequently, the correlations of lip canting with these horizontal and sagittal planes were investigated. RESULTS: The mandibular symmetry plane, the occlusal plane, Camper's plane, the mandibular plane, Broadbent's plane, and the nasal axis plane were correlated with the amount of lip canting (Pearson's correlation coefficients: 0.761, 0.648, 0.556, 0.526, 0.438, and 0.406, respectively). Planes associated with the lower part of the face showed the strongest correlations; the strength of the correlations decreased in the midfacial and cranial regions. None of the planes showed statistically significant differences between patients with clinical lip canting (> 3°) and those without prominent lip canting. CONCLUSIONS: The findings of this study suggest that lip canting is strongly correlated with the mandibular symmetry plane, which includes menton deviation. This finding may have clinical implications with regard to the treatment of patients requiring correction of lip canting. Further studies are necessary for evaluating changes in lip canting after orthognathic surgery.

The validity of marker registration for an optimal integration method in mandibular navigation surgery.

PURPOSE: The aim of this study was to verify the accuracy of 2 registration methods (marker-based registration and marker-free registration) during mandibular navigation surgery. MATERIALS AND METHODS: Two point-to-point registration methods (marker-based registration and marker-free registration) were tested using software and navigation equipment: 1) 3 implanted orthodontic screws and 2) 3 anatomic points on the cusp tips of the teeth (central incisor and first molars bilaterally). RESULTS: For the navigation equipment, the 3-point matching method of screw references was more accurate for all anatomic areas except the coronoid process and second premolar alveolar area. The registration error was largest for the condyle area. Errors were larger than 2.0 mm in the condyle, condyle neck, sigmoid notch, coronoid process, posterior border, lingula, and angle areas. In the oblique ridge, mental foramen, and dentoalveolar areas, the registration error using screws was smaller than 1.5 mm. For the software, tooth cusp references were more accurate for anatomic areas such as the mental foramen and dentoalveolar areas, but not the molar area. In all cases, the registration error was smaller than 1.0 mm, and that for the first molar was similar between the tooth tip overlap and the screw overlap. CONCLUSIONS: Registration using screws generally was more accurate than registration using tooth cusps for mandibular navigation surgery. However, tooth tip references can be used for registration in dentoalveolar surgery.

Three-dimensional anatomic analysis of mandibular foramen with mandibular anatomic landmarks for inferior alveolar nerve block anesthesia.

OBJECTIVE: We sought to standardize 3-dimensional anatomic positioning of the mandibular foramen (MnF) for inferior alveolar nerve block anesthesia. STUDY DESIGN: Three-dimensional mandibular computerized tomography (CT) images were reconstructed from data for 49 patients aged 8-16 years (growth group) and 59 patients aged 18-25 years (adult group). To measure MnF position, we defined 5,6 as the superior contact point between the mandibular first molar and second premolar and 5,6 MnFP as the point on the MnF plane intersecting 5,6 at a right angle. The MnF plane passed through the MnF and parallel to the occlusal plane. RESULTS: In the growth group, the distance from the MnF to the anterior ramus increased with age, as did distance from the gonion to MnF. CONCLUSIONS: Measurements correlated significantly with age in the growth group. Needle insertion at an obtuse angle in the MnF plane from the contralateral first molar is appropriate for inferior alveolar nerve block anesthesia.

Three-dimensional analysis of maxillary anatomic landmarks for greater palatine nerve block anesthesia.

Greater palatine nerve block anesthesia (GPNBA) is a local anesthetic procedure used for maxillary and nasal treatment. Investigation of the three-dimensional anatomic location of the greater palatine foramen (GPF) is important for successful local anesthesia. The study aim was to provide standards for anatomic structures in the oral cavity that can be easily referred to in GPNBA. Maxillary computed tomography data were obtained from patients between 8 and 16 years of age whose maxillary incisors and first molars had already erupted (the growth group, n = 103); changes in the maxilla were observed over time in this group. Reference values for GPNBA in adults were measured in 107 patients older than 18 years. Maxillary computed tomography images were reconstructed three-dimensionally. Regression analysis demonstrates that all maxillary measurements in the growth group except for the distance from the posterior nasal spine to the GPF in the coronal plane correlated significantly with age. In adults, the mean perpendicular distance from the interdental alveolar bone between the left and right central incisors (1alvB) to the GPF in the coronal plane was 46.16 mm, and the mean distance from 1alvB to the GPF was 51.05 mm. The mean distance from the maxillary central incisor to the GPF was 57.58 mm. The mean angle between the line from the maxillary central incisor to each GPF and the sagittal plane was 16.49 degrees. The mean perpendicular distance from the anterior nasal spine to the GPF in the coronal plane was 43.49 mm, whereas the mean perpendicular distance from the GPF to the bone plane was 12.67 mm, and the mean perpendicular distance from the GPF to the occlusal plane was 22.13 mm. These measurements can be used to find the height of the GPF. In adults, the measured perpendicular distance from the incisive foramen to the GPF in the coronal plane was 32.04 mm, and the perpendicular distance from the median of the line that connects both of the contact points between the maxillary tuberosity and the pterygoid plate to the GPF in the coronal plane was 5.23 mm. Three-dimensional reference values relative to the anatomic structures in the oral cavity may increase the success rate of GPNBA and reduce complications. Although the maxillary growth pattern was analyzed, a limitation of this study is that maxillary anatomic measurements were not analyzed with regard to race or ethnicity.

Oculomotor Nerve Palsy due to an Odontogenic Abscess Originating from the Mandibular Third Molar.

We report a case of oculomotor nerve palsy (ONP) as a result of odontogenic infection originating from the third molar, which is considered rare.