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.

Digital Radiographic Evaluation of the Quality of Different Root Canal Obturation Techniques in Deciduous Mandibular Molars after Preparation with Rotary Technique.

STATEMENT OF THE PROBLEM: Several factors affect the success of pulp therapy of primary teeth, including cleaning and shaping of the root canals and the quality of obturation as the most important steps. PURPOSE: The aim of the present study was to compare the quality of different root canal obturation techniques in deciduous mandibular molars subsequent to preparation of the root canals with the rotary technique, using the photo stimulated phosphor (PSP) digital radiographic technique. MATERIALS AND METHOD: In this in vitro study, 221 root canals were selected in 80 extracted deciduous mandibular second molars. The root canals were prepared with a modified protocol for ProTaper NiTi rotary files and with only two instruments (SX and S2) and obturated using a lentulo spiral, condensation technique, an anesthetic syringe, and tuberculin syringe techniques with ZOE paste. The quality of the root canal obturation (obturation length and the number and sizes of the voids) was evaluated using PSP radiographic technique. Data were analyzed with SPSS 21, using chi-squared, Kruskal-Wallis and Mann-Whitney tests. RESULTS: There were no significant differences in the obturation length (p= 0.285) and the number of voids (p= 0.061) between the study groups; however, there were significant differences in void sizes between the study groups (p= 0.001). The condensation and tuberculin syringe groups exhibited the best and worst results considering the obturation length, respectively. Lentulo and anesthetic syringe techniques have also exhibited acceptable results. The condensation and anesthetic syringe groups exhibited the minimum and maximum number of voids, respectively. The condensation and lentulo groups exhibited the maximum and minimum void sizes, respectively. CONCLUSION: If implemented correctly, there will be no significant difference among the experienced root canal obturation techniques considering obturation length and the number of voids.

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.