Factors affecting the maxillary and mandibular incisors' buccolingual inclinations and buccal and lingual cortical plate heights.

INTRODUCTION: Orthodontics is closely related to periodontics. The buccolingual inclination (BLI) of the incisors and deficiencies in their buccal (BHd) and lingual (LHd) cortical plate heights may affect orthodontic outcomes. Identifying risk factors that can compromise buccal or lingual bone heights may have clinical value. The literature on BLI/BHd/LHd is not only scarce but also limited to one jaw. We aimed to examine, for the first time, factors affecting BLI/BHd/LHd not evaluated before as well as other factors with scarce literature about them. METHODS: In this two-phase epidemiological and analytical study, inclinations and cortical heights of 248 incisors (bilateral centrals and laterals) were evaluated blindly on 62 randomly selected high-resolution pretreatment cone-beam computed tomography volumes (30 maxillae [13 men, 17 women], 32 mandibles [13 men, 19 women]). The sample was balanced in terms of sexes, jaws, and ages. The BLI/BHd/LHd of bilateral incisors were measured (intraobserver agreement > 95%). The effects of jaws, sexes, age, sides, and incisor types on each of the anatomical variables (BLI/BHd/LHd) were analyzed using a Mixed-Model Multiple Linear Regression analysis. Correlations among continuous variables were assessed using a Pearson coefficient (α = 0.05). RESULTS: For the maxillary centrals, BLI, BHd, and LHd were 106.79 ± 5.06, 1.94 ± 0.95, and 1.50 ± 0.76, respectively. These parameters were '110.56 ± 5.97, 1.81 ± 0.83, 1.23 ± 0.69' for the maxillary laterals; '97.64 ± 8.26, 2.98 ± 1.48, 3.46 ± 1.45' for the mandibular centrals; and '95.98 ± 6.80, 3.29 ± 1.72, and 2.73 ± 1.15' for the mandibular laterals. BLI was greater in the maxilla compared to the mandible and in the lateral incisors compared to centrals (P < 0.05). BHd was greater (more deficient) in the mandible (P = 0.000). Age, sex, or side were not associated with BLI (P > 0.05). Age, sex, side, or incisor types were not associated with BHd (P > 0.05). LHd was greater in the mandible, older individuals, and centrals (P < 0.05). There were some significant but weak correlations between BLI with BHd and especially LHd (P < 0.05). CONCLUSION: In the maxilla, but not in the mandible, incisors' BLI may determine LHd. Maxillary incisors may have greater BLIs as well as greater buccal and lingual alveolar bone heights compared to mandibular incisors. BLI might be greater in the laterals compared to the centrals in both jaws combined.

Anatomy of the Posterior Superior Alveolar Artery: a Cone-Beam Computed Tomographic Study.

Introduction: Posterior superior alveolar artery (PSAA) is a major part of the circulation of the sinus floor. This study aimed to analyze the anatomy of PSAA in an Iranian population for the first time. Methods: This study was performed on coronal CBCT slices of 400 hemimaxillae (1598 slices through premolar and molar areas), to evaluate the PSAA's prevalence, diameter, and its vertical distances from the sinus floor and the alveolar ridge. Potential associations between anatomical properties with age, gender, and maxilla sides were assessed statistically (α = 0.05, 0.0125). Results: The PSAA was detected in 73.2% of all slices (58.5%, 79.6%, 71.5%, and 83.0%, in P1-M2 areas, respectively). The mean PSAA diameter was 0.83 ± 0.33 mm (95% CI 0.81-0.85; 0.96, 0.85, 0.80, and 0.74 mm, in P1-M2 areas, respectively). Canals > 2 mm in diameter were seen only in M1 (0.4%) and M2 (0.9%) areas. Conclusions: PSAA diameters were smaller in this population than all others, with very few large canals available. Although the average diameter increased in the anterior regions, large canals were not present in these regions. Males tended to have larger PSAAs. Age might not change canal parameters. Gender might affect canal diameter. Right/left sides are similar.

Accuracy of High- and Low-Resolution Cone-Beam Computed Tomographic Scans in the Detection of Impacted Tooth-Induced External Root Resorption: An Ex-Vivo Study.

OBJECTIVES: Cone-beam computed tomography (CBCT) is used in diagnostic situations, as well as tooth impaction and its complications. A possible sequela of tooth impaction is resorption of adjacent teeth, complicating the treatment plans. This study aimed to determine the diagnostic accuracy of high- and low-resolution CBCT scans in the detection of external root resorptions (ERRs), caused by an adjacent impacted tooth in the cementoenamel junction (CEJ), mid-root, and apical areas. MATERIALS AND METHODS: Forty-five intact single-rooted teeth were divided into three groups of 15. Each group was dedicated to each zone of the root. Slight, moderate, and severe ERRs were formed, and CBCT scans were taken before and after the formation of ERRs. The diagnostic accuracy was assessed, and the Proportion test was used to compare the results. RESULTS: The statistical analyses of high- and low-resolution images showed a significant difference (P<0.05), which implies the higher accuracy of high-resolution images. The highest diagnostic accuracy among different zones was related to the mid-root, and the lowest was related to the apical zone. In terms of the size of ERRs, the diagnostic accuracy was the lowest for slight ERRs. CONCLUSION: The most reliable and accurate diagnostic mode was found in high-resolution images, in the mid-root zone, and with severe ERRs. The lowest diagnostic accuracy was found in low-resolution images, in the apical zone, and with slight ERRs.

Effect of Field of View and Resolution in Detection of Horizontal Root Fractures in CBCT images: An In Vitro Study.

Introduction: New cone-beam computed tomography (CBCT) devices are capable of imaging with different resolutions and field of views (FOVs), in which higher resolutions and FOVs impose a higher dose to the patient. This study was an attempt to investigate the detection accuracy from different FOVs and resolutions in detection of horizontal root fractures. Methods and Materials: Through this experimental study, in five different field of views (FOV) and resolutions (voxel size) of New Tom VGi CBCT (Italy) system was used to scan fifty teeth with horizontal root fractures in half of them. The images were evaluated by four observers (two maxillofacial radiologists and two general dentists) who recorded the presence or absence of horizontal root fractures. The data were analyzed by SPSS 22 software and MacNemar and kappa test were used to compare results with reality. Results: The highest sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy (AZ) were attributed to 8×8 FOV and high resolutions (0.125 mm voxel size) but the difference between sensitivity, specificity, PPV and NPV was not significant. Kappa values for inter-observer agreement between radiologists and general dentists and also intra-observer agreement were in excellent ranges. The highest Kappa in both cases was attributed to 8×8 FOV and high resolutions. Conclusion: There was no significant difference to diagnose of horizontal root fracture between two observer groups and for all of the FOVs and voxel sizes.

Accuracy of CBCT, Digital Radiography and Cross-Sectioning for the Evaluation of Mandibular Incisor Root Canals.

INTRODUCTION: The aim of this study was to compare the accuracy of cone-beam computed tomography (CBCT), digital radiography and tooth sectioning in evaluating root canal morphology of mandibular incisors in an in vitro setting. METHODS AND MATERIALS: A total of 76 samples were imaged using CBCT, and digital radiography in straight and angled views. The samples were then sectioned at different distances from the apex for further visualization under stereomicroscope. The agreement between the observers was statistically analyzed by kappa correlation coefficient and the chi-square test. RESULTS: The results showed that the majority of the samples had a single canal (Vertucci's Type I). CBCT analysis reported more frequent multi-canal roots in comparison with the other techniques. In pairwise comparisons, the highest agreement was found between digital radiographic imaging and microscopic cross-sectioning both in terms of canal configuration and the number of root canals. CONCLUSION: None of the used imaging techniques per se could adequately show the exact internal anatomical configuration in accordance with the gold standard.

Rare appearance of an odontogenic myxoma in cone-beam computed tomography: a case report.

Odontogenic myxoma (OM) is an infiltrative benign bone tumor that occurs almost exclusively in the facial skeleton. The radiographic characteristics of odontogenic myxoma may produce several patterns, making diagnosis difficult. Cone-beam computed tomography (CBCT) may prove extremely useful in clarifying the intraosseous extent of the tumor and its effects on surrounding structures. Here, we report a case of odontogenic myxoma of the mandible in a 27-year-old female. The patient exhibited a slight swelling in the left mandible. Surgical resection was performed. No recurrence was noted. In the CBCT sections, we observed perforation of the cortical plate and radiopaque line that extended from the periosteum, resembling "sunray" appearance-a rare feature of OM-which could not be assessed by panoramic radiography.

The accuracy of single emulsion radiographic film in linear measurement of spiral tomography.

BACKGROUND: Conventional tomography used for evaluation of the small areas of the jaws provides acceptable information. It has some advantages of availability, less radiation dose and cost in comparison to computed tomography (CT) and cone beam CT. Double emulsion film usually used for taking tomograms requires less exposure than single emulsion film; on the other hand, the latter provides more sharpness and spatial resolution. The aim of this study was to compare diagnostic accuracy of these two kinds of films in the spiral tomography. MATERIALS AND METHODS: In an experimental study, 20 lines (10 lines anterior and 10 lines posterior to the mental foramen) were selected on two dry human mandibles and tomographic images were taken from each line with and without metal marker by single and double emulsion films. For quantitative assessment, the mandibular width and length was identified and measured on 80obtained tomograms. Afterwards, the mandibles were sectioned on each line and their actual width and height were measured. For each line, the data of tomograms were subtracted from gold standard as measurement error. These errors were divided into three groups: Greater than +1 mm, between +1 mm and -1 mm and less than -1 mm. Obtained data were analyzed by Pearson Chi-square test (α=0/05). RESULTS: There was no significant difference between the single and double emulsion films, with and without markers in the measurement of both height and width of mandible (P > 0.05). CONCLUSION: The single emulsion film is not recommended to be used for taking the spiral tomogram.