In-vitro comparison of instrumentation time and cleaning capacity between endodontic handpiece and manual preparation techniques in primary molar teeth.

AIM: The aim of this study was to evaluate and compare the cleaning ability and instrumentation time of manual method and use of endodontic handpiece for preparation of primary molar teeth. METHODS: Forty primary teeth canals were used in this experimental study. Access cavities were prepared and India ink was injected into the canals. The samples were divided into three groups according to the preparation technique. In the first group the root canals were manually instrumented by k_files. Endodontic handpiece (TEP-ER10, NSK, Japan) were used for canal preparation in the second group and the samples in the third group (control) were not instrumented. After preparing the canal, the teeth were cleared with methyl salicylate and the removal of India ink was measured in the cervical, middle and apical thirds. The instrumentation time was transcribed by chronometer. Statistical analysis was performed using Mann-Whitney and t-test. RESULTS: There was no significant difference in cleaning capacity between the two techniques, but results of the first and second group differ from those of the control group. In fact, time taken for preparation was significantly shorter with endodontic handpiece system. CONCLUSION: Seen the shorter working time of endodontic handpiece and the similar cleaning ability of the two techniques, the application of the endodontic handpiece is recommended for preparation of deciduous root canals during pulpectomy.

Mutational Status of FGFR3 in Oral Squamous Cell Carcinoma.

OBJECTIVE: Head and neck squamous cell carcinoma, including oral squamous cell carcinoma (OSCC) is the sixth most common cancer in the human population. Despite significant efforts committed in treatment of OSCC the overall survival rate of OSCC has not improved significantly. Activating mutations in the fibroblast growth factor receptor 3 (FGFR3) genes are responsible for some human cancers, including bladder and cervical carcinoma. Despite a high frequency in some benign skin disorders, FGFR3 mutations have not been reported in cutaneous malignancies. Therefore, FGFR3 gene may play a role in epithelial biology and mutations of FGFR3 gene may contribute to the development of OSCC. MATERIALS AND METHODS: In this cross-sectional study, DNA was extracted and purified from snap frozen tissue biopsy sections of 20 OSCC cases. Exons 7 and 15 were amplified by polymerase chain reaction (PCR) and sequenced in both directions. RESULTS: In three cases silent mutations were identified in exon 7 (882 T to C) which may be introduced as Single Nucleotide Polymorphism (SNP) and no mutation was identified in exon 15. CONCLUSION: FGFR3 gene mutation in exon 7 and 15 has no significant role in the development and progression of OSCC. Analyzing other exons or considering other advanced gene mutation assessment techniques may clarify the role of this receptor mutation in OSCC pathogenesis.

Microleakage and marginal gap of adhesive cements for noble alloy full cast crowns.

Very limited comparative information about the microleakage in noble alloy full cast crowns luted with different types of adhesive resin cements is available. The purpose of this study was to evaluate the microleakage and marginal gap of two self-adhesive resin cements with that of other types of adhesive luting cements for noble alloy full cast crowns. Fifty noncarious human premolars and molars were prepared in a standardized manner for full cast crown restorations. Crowns were made from a noble alloy using a standardized technique and randomly cemented with five cementing agents as follows: 1) GC Fuji Plus resin-modified glass ionomer cement, 2) Panavia F 2.0 resin cement, 3) Multilink Sprint self-adhesive resin cement, 4), Rely X Unicem self-adhesive resin cement with pretreatment, and 5) Rely X Unicem with no pretreatment. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution, vertically cut in a mesiodistal direction and evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a nonparametric Kruskal-Wallis test followed by Dunn multiple range test at a p<0.05 level of significance. The Rely X Unicem (with or with no pretreatment) exhibited the smallest degree of microleakage at both tooth-cement and cement-crown interfaces. The greatest amount of microleakage was found for Panavia F 2.0 resin cement followed by GC Fuji Plus at both interfaces. No statistically significant difference in the marginal gap values was found between the cementing agents evaluated (p>0.05). The self-adhesive resin cements provided a much better marginal seal for the noble alloy full cast crowns compared with the resin-modified glass ionomer or dual-cured resin-based cements.

Evaluation of bax and bcl-2 expression in odontogenic keratocysts and orthokeratinized odontogenic cysts: A comparison of two cysts.

Odontogenic keratocyst (OKC) has an aggressive clinical course and a high tendency toward recurrence, while orthokeratinized odontogenic cyst has different characteristics and does not show aggressive behavior. Bax and bcl-2 are two important anti-apoptotic and pro-apoptotic factors of the bcl-2 family. The different outcomes of theses two cysts could be related to these apopto-proteins. Twenty-eight cases of OKC and nine cases of orthokeratinized odontogenic cyst (OOC) were stained for bax and bcl-2 proteins. Immunoreactivity for bcl-2 was detected in the basal layer of OKCs, while OOCs were completely negative in the basal layer (P<0.001). Bcl-2 expression in the whole thickness of OKCs was also significantly higher than in OOCs (P<0.001). Bax expression did not show any statistically significant difference between the two cysts (P=0.077). The different behaviors of these cysts are compatible with their immunohistochemical view. Lower expression of bcl-2 in OOC ends in less aggressiveness and a lower tendency toward recurrence. Bax seems to play no significant role by itself; however, the bcl-2/bax ratio is probably a determinant factor for different outcomes.