Evaluation of resistance form of different preparation features on mandibular molars.

Aims: Resistance form of full metal-ceramic crown is an important feature that determines longevity of these restorations. This study evaluated the resistance form of full metal-ceramic prepared with four different design features. Materials and Methods: An acrylic tooth was prepared with 20° total occlusal convergence (TOC) angle, 2.5 mm of occlusocervical dimension and a shoulder finishing line. This design lacked resistance form. The crown preparation was subsequently modified by preparing Mesial Occlusal Distal isthmus, placing occlusal inclined plane, and reducing TOC. Four metal dies from these designs were constructed by lathe machine and then 10 metal copings were fabricated for each preparation. Metal coping were cemented on metal dies with temp-bond cement. Force was applied at 45° from lingual to buccal direction with universal testing machine. Statistical analysis used: The data were evaluated by Kruskal-Wallis and non-parametric Mann-Whitney test. Results: All features increased resistance form when compare to control group. However, reduce TOC group showed greatest value of resistance. Conclusion: Within the limitation of this study, reducing the tapering of occlusocervival dimension is the most effective way in increasing resistance form, although, other features were also effective.

Assessment of proportion of central incisor width in the maxilla to that in the mandible in natural and artificial teeth

Selection of appropriately-sized central teeth has an important role in esthetics of dentures. The aim of this study was to compare proportion of mesiodistal width of central incisors in the maxilla to those in the mandible in students and products of ldealmako Company. In this descriptive-analytical study, 93 students of Isfahan Faculty of Dentistry in the age range of 20-30 were selected randomly. Mesiodistal widths of left and right upper and lower centrals were recorded by two methods: directly, using an intraoral caliper, and indirectly, using subjects' casts and a caliper with an accuracy of 0.01 mm at height of counter of the teeth three times. The sizes of Idealmako products were measured by the same caliper. Data was analyzed by one-way ANOVA, t-test and post hoc Scheffe's test using SPSS software [alpha = 0.05]. Proportion of upper-to-lower mesiodistal width of centrals was 1.55 +/- 0.13 in students and 1.68 +/- 0.17 in Idealmako products. Mean proportion of mesiodistal width of upper centrals to lower centrals in natural teeth is less than that in artificial teeth. A similarity between the width of upper centrals in the natural and artificial teeth [the numerator of the fraction] accounts for this significant difference between the proportion of the two groups, leading to the very small size of lower centrals [denominator of the fraction] in Idealmako artificial teeth

Anesthetic management in a case of Klippel-Feil syndrome and literature review

Klippel-Feil syndrome is known by the classic triad of shortness of the neck, limitation of neck movements, and a low posterior hairline. There are often accompanying cervical spinal abnormalities such as kyphoscoliosis as well as urogenital and cardiac abnormalities. Presented here we have a 20 year old young man with hypoesthesia and decreased motor function in the right hand. The problem began one year back following a minor head trauma and had a progressive course involving the legs, especially the feet. Cervical magnetic resonance imaging was compatible with C3-C4 cord compression as well as blocked vertebrae. The patient was evaluated to be in Mallampati class II. Endotracheal intubation was performed employing gentle manual axial traction in both anterior and posterior operative approaches without any neurological sequela. It is recommended that in situations where fiberoptic or Bullard laryngoscopes are not available and Mallampati class is low, direct laryngoscopy associated with gentle axial traction may be a plausible substitute