Influence of intraoral application of antiseptics and fluorides during orthodontic treatment on corrosion and mechanical characteristics of nickel-titanium alloy in orthodontic appliances.

OBJECTIVES: To explore whether the commercial agents recommended for controlling dental biofilm formation had a significant effect in vivo on mechanical and corrosion properties of nickel-titanium (NiTi) alloy. MATERIALS AND METHODS: NiTi archwires (dimensions 0.508 × 0.508 mm) were collected from 36 orthodontic patients aged 13-42 years after a 3-month intraoral exposure. Three experimental groups were formed: (1) subjects conducting regular oral hygiene, (2) subjects who used fluorides for intensive prophylaxis for the first month, and (3) subjects who used chlorhexidine in the same manner. Corrosion behavior, surface characteristics, stiffness, hardness, and friction were analyzed. RESULTS: Exposure to intraoral conditions significantly reduced the stiffness and hardness of the NiTi alloy (P ≤ .015). Fluoride tended to reduce stiffness and hardness more than did saliva or antiseptic, but not significantly. Roughness and friction were not significantly influenced by oral exposure. Intraoral aging predominantly produced general corrosion independent of the adjuvant prophylactic agent, although localized corrosion may also have occurred. CONCLUSIONS: Fluorides and the antiseptic chlorhexidine do not increase corrosion more than saliva itself, nor do they further modify the mechanical properties of the NiTi alloy.

Nanostructured endodontic materials mixed with different radiocontrast agents-biocompatibility study.

The aim of this study was to investigate the biocompatibility of nanostructured materials based on highly active calcium silicates mixed with different radiocontrast agents in comparison to MTA+ using in vitro and in vivo model. Morphology of materials' samples was analyzed using SEM while the phase compositions were identified by XRD. pH values of materials' suspensions were conducted by pH-meter. The cytotoxicity of materials' solutions was tested by MTT test (100, 50, 25 and 12.5 mg/ml). LDH and 3H-thymidine assay were utilized for biocompatibility investigations of materials' eluates (24 h, 7 day and 21 day). Eighteen Guinea pigs were used for intramuscular implantation, as teflon tubes with freshly prepared materials were placed into intramuscular pockets. All samples were composed of round and needle-like particles equally distributed with Ca/Si ratio ~2.7 at%, with the presence of hydrated calcium silicate phases. The pH values of ALBO-MPCA1 and ALBO-MPCA2 were high alkaline, while in case of MTA+ they were lower and continuously declined (p < 0.05). Investigated materials didn't exhibit dose-dependent effect on metabolic activity of L929 cells (p > 0.05). Significant differences in the percentage of cytotoxicity between diluted and undiluted extracts between all tested materials after 24 h and 7 day were noticed (p < 0.05). Increase in L929 cells proliferation was noticed in case of undiluted eluates of ALBO-MPCA1 and ALBO-MPCA2 after 7 day (p < 0.05). There were no statistically significant differences in the intensity of inflammatory response between investigated materials and control group after 60 day (p > 0.05). Evaluation of biocompatibility of both ALBO-MPCA1 and ALBO-MPCA2 indicate their potential clinical use.

Biocompatibility Investigation of New Endodontic Materials Based on Nanosynthesized Calcium Silicates Combined with Different Radiopacifiers.

INTRODUCTION: The aim of this article was to analyze biocompatibility and bioactivity of new endodontic materials on the basis of nanosynthesized calcium silicates (ALBO-MPCA1 and ALBO-MPCA2) combined with different radiopacifiers in comparison with MTA+. METHODS: Morphology of the samples was studied by scanning electron microscopy, and the pH and ion release analysis were also assessed. Biocompatibility of materials' eluates (24-hour, 7-day, and 21-day) was conducted by using MTT test. Twelve New Zealand white rabbits were used for intraosseous implantation. Four calvarial defects per animal were created and filled with freshly prepared investigated materials. RESULTS: Samples mostly consisted of agglomerates built up from nanoparticles, preferably spherical and rod-like. There was no significant difference among pH values of materials' eluates after 24 hours (P > .05). The amount of calcium and aluminum ion release decreased, whereas the amount of magnesium and bismuth (ALBO-MPCA1, MTA+) and barium (ALBO-MPCA2) increased during 21-day period. The metabolic activity of cells increased after the extraction time, except in case of undiluted elutes of ALBO-MPCA2 and ALBO-MPCA1 (21-day). Histologic analysis of the samples revealed newly formed bone tissue with moderate inflammation for all investigated materials, which subsided during 90-day period to mild. Both MTA+ and ALBO-MPCA1 were in direct contact with the newly formed bone tissue. After 90 days, statistically significant difference in hard tissue formation was observed in comparison of MTA+ and ALBO-MPCA1 with control group (P < .05). CONCLUSIONS: Experimental materials ALBO-MPCA1 and ALBO-MPCA2 possess both biocompatibility and bioactivity. Because ALBO-MPCA1 provokes favorable biological response, it is especially good candidate for further clinical investigations.

Sexual Dimorphism in the Dimensions of Teeth in Serbian Population.

The study of teeth is of great interest to anthropologists, biologists, orthodontists and forensic scientists. The existence of sexual dimorphism in permanent teeth is a known phenomenon. Aim of this study was to analyze the presence of sexual dimorphism in the mesiodistal and vestibulolingual diameter of permanent teeth in the sample of Serbian population. Measurements were taken on plaster casts of 201 individuals of both sexes, ages between 18-25 years, using a digital caliper with 0.01 mm precision. The mesiodistal and vestibulolingual diameter of each permanent tooth was determined. A Student's t-test and a Mann-Whitney U test were used to statistically analyze the obtained results. There were no statistically significant differences in the teeth crown diameter between the right and left side of the same dental arch. Majority of the teeth examined were larger in male than in female patients. Statistically significant difference in the mesiodistal diameter of male and female maxillary and mandibular canines was found. The results of this study indicate that there are significant differences in teeth size between sexes in Serbian population. Males have larger diameters in teeth crowns than females. Canines show the greatest dimorphism.

Use of mineral trioxide aggregate in the treatement of traumatized teeth in children--two case reports.

INTRODUCTION: Dental injuries in immature permanent teeth often result in endodontic complications. Apexification technique using calcium hydroxide is associated with certain flaws, such as long treatment time, the possibility of tooth fracture and incomplete calcification. The use of an apical plug employing mineral trioxide aggregate (MTA) is an alternative treatment option. CASE REPORT: We reported the successful treatment of 4 maxillary incisors (in a 7-year-old boy and a 10-year-old girl) with open apices and periapical lesions. Apical portions of the canals were filled with MTA plugs in both cases. Coronal parts of the root canals were filled with gutta-percha and sealer. Clinical findings were clear 6 months after the definite obturation with no pathological changes on the radiographs in both cases. CONCLUSION: The use of MTA for apical plugging appears to be a valid treatment option in traumatized immature teeth with endodontic complications.