TEMPORARY REMOVAL: A method to isolate forces and moments applied to teeth: An in vitro experiment.

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A comparative study of histologic response to different pulp capping materials and a novel endodontic cement.

OBJECTIVE: The aim of this study was to compare dogs' pulp response to capping with calcium hydroxide cement (Dycal), mineral trioxide aggregate (MTA), and a novel endodontic cement (NEC). STUDY DESIGN: Twenty-four canine teeth in 6 beagle dogs were buccocervically exposed and capped with MTA, Dycal, or NEC. Eight weeks later, retrieved samples were observed by optical microscope to grade inflammation, formation of dentinal bridge, calcification, necrosis, and presence of odontoblast cells. RESULTS: No inflammation was observed in MTA and NEC groups, and in 75% of each, dentinal bridge was completely formed. In the Dycal group, inflammation and incomplete dentinal bridge were detected in all cases. Although MTA and NEC groups had no significant difference between them in each measure, the difference between all 3 groups was significant (P < .001). CONCLUSION: MTA and NEC showed similar favorable biologic response in pulp cap treatment, better than Dycal, especially in inducing the formation of dentinal bridge.

Histopathological evaluation of pulpotomy with Er,Cr:YSGG laser vs formocresol.

The purpose of this study was to histologically investigate whether pulpotomy with Er,Cr:YSGG laser is an acceptable alternative for formocresol. Pulpotomy of 48 dog's primary canine teeth was performed with formocresol or Er,Cr:YSGG laser. Histological evaluations on hematoxylin and eosin-stained pulp tissues were made by an optical microscope 7 or 60 days later. Statistical analysis was performed with Fisher's exact test, Mann-Whitney U test, and Student's t test. Seven days after pulpotomy, samples treated with laser had significantly favorable histological features in the following measures: continuity of odontoblastic layer (P<0.001), presence of hemorrhage (P<0.008), amount of inflammation (P<0.002), tissue necrosis (P<0.001), internal resorption (P<0.002), level of vascularization (P<0.002), and size of abscess (P<0.041). Similar results were observed 60 days after pulpotomy, except that the differences were not mostly significant due to natural exfoliation of 16 teeth. In conclusion, Er,Cr:YSGG laser system is an acceptable alternative for formocresol in pulpotomy of deciduous teeth.

Effect of smear layer on sealing ability of canal obturation: a systematic review and meta-analysis.

The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro. PubMed was searched for articles published between 1975 and 2005, and results were categorized based on the method of leakage test. Among 26 eligible papers with 65 comparisons, 53.8% of the comparisons reported no significant difference, 41.5% reported a difference in favor of removing the smear layer, and 4.7% reported a difference in favor of keeping it; differences were significant (p<0.001). Of the 65 comparisons, 44 used the dye leakage test for evaluation. The combined effect in this group showed smear layer removal decreases dye leakage (z-score=0.37, z=2.31, p=0.021). According to meta-regression, obturation type, test site and duration, sealer and dye, and publication year had no effect on the results. Under the conditions of these in vitro leakage studies, it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer, did not produce significant effects.

The effects of loading time on osseointegration and new bone formation around dental implants: a histologic and histomorphometric study in dogs.

BACKGROUND: Immediate loading of dental implants has been introduced as a method of reducing implant treatment time without compromising its prognosis. In this research, the effects of loading time on the amount of bone-to-implant contact and bone formation around dental implants were evaluated histologically. METHODS: Three months prior to implantation, the lower premolar teeth of 15 dogs were extracted. Three or four dental implants were placed in the healed extraction sites for each dog (N = 48). Dividing the dogs into three groups, the implants were either loaded 48 hours or 1 week later with metallic or prefabricated acrylic crowns or were left unloaded until the time of sacrifice. Three months after implant insertion, the animals were sacrificed and samples were investigated to define the amount of bone-to-implant contact, lamellar and woven bone percentage, and local inflammation of the newly formed bone. RESULTS: No significant difference in the observed criteria was reported among the three groups (P >0.05); however, the unloaded group had the highest degree of bone-to-implant contact and the group loaded 48 hours after the primary implant insertion had the least. The prosthesis type had no significant effect on the implant success rate (P >0.05). The lamellar and woven bone percentage of newly formed bone also did not differ in the three groups (P >0.05). One implant from each group failed in this study. CONCLUSION: Loading time does not seem to significantly affect the degree of osseointegration and bone-to-implant contact and the composition of newly formed bone around dental implants.

Diagnostic value of silver nitrate staining for nucleolar organizer regions in selected head and neck tumors.

BACKGROUND: The present study is aimed to assess the usefulness of silver nitrate staining of nucleolar organizer regions (NORs) as a quantitative criterion for the diagnosis of selected head and neck tumors. MATERIALS AND METHODS: The silver nitrate staining technique was used on 195 paraffin blocks collected from 85 patients. The samples consisted of 21 squamous cell carcinoma (SCC) of larynx, 28 SCC of oral mucosa and 36 samples of most common salivary gland tumors. Mann-Whitney U-Test was used for data analysis. RESULTS: A significant difference was seen in the number of AgNOR dots between oral and laryngeal SCC with surrounding dysplastic and normal tissues (P < 0.001) and also between mucoepidermoid carcinoma and adenoid cystic carcinoma with pleomorphic adenoma and normal salivary gland tissue (P < 0.001). CONCLUSION: The silver nitrate staining for NORs is a useful method for aiding the diagnosis of malignant and dysplastic mucosal lesions and also malignant and benign salivary gland tumors.