Gravity and capillarity insignificantly affected bacterial leakage. Although gravity and capillarity did not affect bacterial penetration when applied to the coronal access of endodontically treated teeth, it seems that they can promote penetration of India ink into the canal after the bacterial test on the same tooth.

Purpose: Two important factors in dental prosthesis are making an accurate impression and producing a suitable cast which represents the exact relationship between prepared tooth and oral structures. This study, aimed to investigate the effects of different combinations of impression and pouring materials on marginal and internal adaptation of premolar zirconia crowns. Material and Methods: Forty maxillary premolars were prepared considering round shoulder finish line. The impressions were made either by additional (Panasil) or condensation (Speedex) silicon, and poured by two different types of gypsum materials (Siladent or GC gypsum) (N=10). Zirconia crowns were fabricated using a CAD-CAM system. The crowns were cemented, and the samples were cut in bucco-lingual direction. Marginal and internal gaps were measured by stereomicroscope (×25). Results: The mean marginal gaps for Pansil-Siladent, Panasil-GC, Speedex-Siladent, and Speedex-GC were 141 μm, 143 μm, 131 μm, and 137 μm respectively. The internal gaps were 334 μm, 292 μm, 278 μm, and 257 μm respectively. The independent T-Student test showed no significant differences in average marginal or internal gap among various impression and gypsum materials or their interactions (p>0.05). Two-way ANOVA test showed no significant differences in maximum marginal or internal gap among various impression and gypsum materials and their interactions (p>0.05). Conclusion: The present study revealed no statistically significant difference in marginal/internal gap among crowns prepared using different combinations of impression-pouring materials evaluated.

Introduction: Occlusal plane orientation affects the esthetic, function, and success of removable or fixed prostheses. The most prevalent index for determination of this plane is the ala-tragus line while there are controversies in the exact location of tragus reference point. Aims: This study aimed to determine the best point on tragus as the posterior reference of ala-tragal line in relation to occlusal plane according to age and sex. Materials and methods: The study included 136 participants of both sexes who were randomly divided into three age groups: 20-35, 36-50, and older than 50. Fox plane was stabilized on incisal edge-occlusal table of maxillary teeth. A lateral photograph was obtained from each participant sitting in predetermined standard position. Using Auto-Cad software, three lines were traced from nasal ala base to superior, middle, and inferior borders of the tragus, and evaluated for being parallel to occlusal plane. Results: The coordination between occlusal plane and ala was 20.5% for superior, 35.6% for middle, and 43.9% for inferior border of tragus. There was a significant difference in the relationship between sex and plane position (p=0.003), while the relationship between age and plane could not reach statistical significance (p=0.65). The results were analyzed using chi-square test, and ANOVA (p<0.05). Conclusions: Ala-inferior border of tragus line was the most parallel, and ala-superior border of tragus line was the least parallel line to the occlusal plane. The parallelism between occlusal plane and ala-superior border was more prevalent in women, while the men demonstrated significantly more parallelism with inferior border of tragus.

No abstract