مجله دانشکده دندان پزشکی اصفهان
سال هفتم شماره 4 (پیاپی 28، زمستان 1390)

Attention to the location and the shape of mandibular canal is necessary to prevent problems during mandibular surgeries. This study was determined the prevalence of superior-inferior position of mandibular canal and its anatomic variations on panoramic radiographs in patients over 18 referring to Khorasgan Dental School.

In this descriptive-analytical study 260 radiographs were examined for variations in the position of mandibular canal. The subjects’ personal data، type of mandibular canal regarding its position based on Nortje‘s classification (high، low or intermediate position in relation to the apex of the first molar root and inferior border of the mandible)، the distance from the superior border of lingula to the center of the ramus، existence of bifid canal and its shape and side and existence of anesthesia problems or impacted teeth on the same side as the bifid canal، were recorded. Data was analyzed by SPSS 10، using chi-squared test (α=0. 05).

The most common canals in relation to their position relative to the first molar area، in descending order، were canals in middle position (55. 8%)، in the low position (35%)، and in the high position (9. 2%)، respectively. No statistically significant differences were observed between the frequency distributions of canal positions (p value = 0. 14%). The average distances from the superior border of lingula to the center of the ramus، in low position، middle position، and high position canals were 10. 7، 11. 35، and 10. 87 mm، with no statistically significant differences (p value = 0. 14).

According to the results، there were no statistically significant differences between the frequency distributions of different positions of mandibular canals in relation to the root apex of the first molar and also between the distances from the lingual to the center of the ramus. Similar studies using CT scan technique are recommended.

Resistant microbial strains are major factors involved in root canal treatment failure. The aim of this study was to compare the antimicrobial properties of different concentrations of colchicine and calcium hydroxide.

In this in vitro study، suspensions containing 5×105 colony-forming units of E. coli، E. faecalis، P. aeuroginosa، S. aureus، normal salivary flora and C. albicans and different concentrations (1، 0. 5، 0. 25، 0. 125 and 0. 0625 mg/mL) of calcium hydroxide and colchicine were prepared. The samples were incubated at 37°C for 24 hours. Then turbidity of the samples was evaluated to determine minimum inhibitory concentration (MIC). Then 0. 1 mL of the broth with no turbidity was cultured on solid medium to determine minimum bactericidal concentration (MBC). In order to make sure of the accuracy of the process، positive، negative and standard controls were also prepared.

In evaluation of sample turbidity after 24 hours، all the tubes containing calcium hydroxide and positive controls showed complete turbidity. In tubes containing colchicine turbidity was found in all the bacterial categories. Only tubes containing Candida albicans with concentrations of 1، 0. 5 and 0. 25 mg/mL of colchicine were clear and lower concentrations showed turbidity. In evaluation of formation of colonies on Sab. Dextrose agar، only plates with 1 mg/mL of colchicine showed no growth.

Only concentrations of 0. 5 and 0. 25 mg/mL of colchicine exhibited inhibitory effects and 1 mg/mL exhibited lethal effect on Candida albicans. None of the two drugs exhibited any inhibitory or lethal effects on other microbial strains.

Generally، the root canal walls become contaminated with MTA during MTA plug placement. On the other hand، the dentinal tubules need to be open for penetration of sealer. The aim of this study was to compare dentinal tubule contamination during MTA apexification between one-visit and two-visit appointments.

In this in vitro experimental study، 38 single-canal human teeth، consisting of two groups of 17 and one control group of 4، were placed in 5. 25% NaOCl for 30 minutes. The tooth crowns were removed at CEJ; then 2 mm of root ends were cut to create open-apex roots. Canal preparation and shaping were performed up to file #100 and Gates Gliden drill #4 using the step-back technique. The smear layer was removed using NaOCl and EDTA. Finally، the canals were dried. In groups one and two، MTA plug was condensed at root end at a thickness of 3 mm. In group one (one-visit)، the samples were prepared for SEM immediately after cleaning the canal walls. In group two (two-visit)، the samples were kept under 100% humidity at 37ºC in an incubator for 24 hours. Then، the canals were irrigated with ultrasonic and 2. 5% NaOCl and prepared for SEM. In the control group، only the smear layer was removed and the samples were prepared for SEM without MTA plug. Mann-Whitney and Kruskal-Wallis statistical tests were used for statistical analysis (α=0. 05).

There was a significant difference between the groups in relation to contamination of the dentinal tubules with significantly more MTA on the canal walls in group one compared to group two (p value < 0. 001). The dentinal tubules were completely open in the control group.

The results of this study showed that in apexification with MTA in open apex teeth، two-visit treatment sessions are superior to one-visit sessions.

In recent years، proportions and harmony of orofacial soft tissues have gained great importance in orthodontics. The aim of this research was to evaluate soft tissue thickness changes of facial midline landmarks during growth in both genders.

In this analytical-descriptive study، lateral cephalometric views of ninety-eight 6-18 year-old patients referring to the Orthodontics Department of Khorasegan Azad University were evaluated. The positions of 7 facial midline landmarks، including glabella، soft tissue nasion، soft tissue points A and B، soft tissue pogonion، and superior and inferior labrale، were determined and then the thicknesses of the landmarks were measured. Data was compared between two groups of under and above 12 years of age between males and females using independent t-test (α=0. 05).

There were no statistically significant differences between the soft tissue thicknesses of both sexes in any of the landmarks except nasion (p value=0. 026) and point B (p value=0. 043) in the group under 12 years of age. Differences between the soft tissue thicknesses in both sexes over 12 years of age were statistically significant in nasion (p value = 0. 043)، point A (p value=0. 001)، and superior labrale (p value<0. 001). Differences between soft tissue thicknesses of all the landmarks were statistically significant between the two age groups in males except point B (p value=0. 119); however، in females only the thickness of soft tissue nasion (p value=0. 105) and superior labrale (p value=0. 968) were not statistically significant between the two age groups.

Soft tissue thicknesses were almost the same in boys and girls except nasion and point B before puberty. After puberty upper face soft tissue thicknesses، including glabella and point A، were greater in boys compared to girls. However، in both sexes، soft tissue thicknesses of facial midline landmarks increased after 12 years of age.