Objective The aim of this study was to compare the stress distribution of teeth with curved and straight roots with oval and round canals restored with the bundle and conventional post systems. Material and methods Six three‐dimensional premolars were modeled with round and oval canals, and curved roots using the software. The bundle post and the round posts were modeled. All post models were placed on the canals. The models were subjected to 200 N oblique loading. The results were evaluated by von Mises stresses. Results This study demonstrated that the bundle post showed higher stress values compared to the conventional post. The stresses in the oval canal were higher than those in the round canal. The highest stress values were found in the curved roots. The stress distribution on the curved roots was observed in the middle and apical third of the canal. Conclusion The bundle post presented higher stress compared to conventional posts. Besides, a more uniform stress distribution was observed in the bundle groups. Clinical significance When a post was required in extremely irregular, wide canals and curved roots, the bundle post was the material of choice. Canal and root morphology influenced stress distribution.

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Background: The primary objective of the study was to assess the buccal bone thickness (BT), evaluate and compare the prevalence of bone fenestration and dehiscence in anterior maxillary teeth using cone-beam computed tomography (CBCT). Methods: Images of 300 maxillary anterior teeth were investigated. The BT was measured at the bone crest, 3, 6 and 9 mm from the bone crest, and apical. Fenestration and dehiscence were recorded according to Yang and Pan's classification. Student's t-test and one-way ANOVA were performed for statistical analysis. Results: Fenestration and dehiscence rates were 35.66% and 20%, respectively. Type III fenestration was higher in group 3 (>65 years) (P = 0.028). Type I and IV fenestration and CII DII dehiscence were more common in canines (P > 0.05). Fenestration involving two-thirds (46.76%) and one-third (44.84%) of the root length was more common. Fenestrations involving the entire root were 8.4%. Most of the dehiscence (63.3%) involved one-third of the root length. Dehiscence involving two-thirds of the root length and the entire root was 5% and 9.95%, respectively. The coexistence of fenestration and dehiscence was 8.3%. Dehiscence on the palatal aspect was detected in 1.65% of the anterior maxilla. Conclusions: The rate of BT ≤1 mm was 80.08%, and ≥2 mm was 3.66%. Fenestration was most common in canines. Fenestration was mostly located in the apical third, while dehiscence was mostly located in the coronal third.

Objective: To investigate buccal and lingual bone thicknesses and fenestration rate of mandibular first and second molars using cone-beam computed tomography (CBCT). Methods: A total of CBCT images of 41 patients were selected and overall 120 mandibular molars were investigated. The buccal and lingual alveolar bone widths were measured at apex of the roots. The prevalence of fenestration in mandibular molars was recorded. Statistical analyses were performed. Results: The buccal bone widths of mesial root of second molars were significantly lower than the lingual (p<0.05). The lingual bone widths of mesial and distal root of second molars were lower than the buccal (p<0.05). The lowest thickness of buccal and lingual bone was observed in mesial root of first molar and distal root of second molar. The prevalence of fenestration in mandibular first and second molars was 5% and 10%. Conclusion: The buccal bone widths were lower at the first molar than the second molar. All fenestrations in first molar were in buccal aspect, in second molar were in lingual aspect. Topographical proximity of the buccal side of first molar and the lingual side of second molar to bone plate create a risky region for endodontic treatment or spread of infection.

Objectives Dentin thickness in concave areas of the root creates risk for complications such as strip perforation during endodontic treatment. The study aims to examine dentin thickness of the danger (DZ) and safety zone (SZ), canal configuration, and the presence of isthmus in the mesiobuccal root of maxillary molars. Material and Methods Cone-beam Computed Tomography (CBCT) images of 1251 teeth belonging to 642 patients were retrospectively reviewed. The dentin thicknesses at DZ and SZ in maxillary molars with one (MB) or two mesiobuccal canals (MB1, MB2) were measured at the 3 mm apical to the furcation level. Vertucci's canal configurations and the isthmus rate were recorded. The Chi-square test andThe Student’s t-test were performed. Results MB2 rate was higher in maxillary first molars (61.68%) than second molars (39.36%). Isthmus rates were 27.3% and 44.11% in first and second molars. DZ thickness was thinner than the dentin thickness in the SZ in both first and second molars with one or two mesial canals (p< 0.05). In teeth with single canal, the mean DZ thickness was 0.88mm. In teeth with two canals, the mean DZ thicknesses were 0.83mm and 0.80mm for MB1 and MB2 canals, respectively. Conclusion MB2 rate was higher in the first molar (61.68%), and the isthmus rate was higher in the second molar (44.11%). DZ and SZ were thinner in MB2 than in MB1 at the maxillary molars with two mesial canals. The results indicated that more conservative preparation must be applied to the MB2 canal in the maxillary molars.