Comparison of Fracture Resistance of Primary Incisors Restored with Different Intracanal-Reinforcement Materials.

AIM: To evaluate the effects of placing short posts made of different restorative materials on the fracture resistance of root canals in primary incisors of primary teeth. MATERIALS AND METHODS: The root canals of 40 extracted primary incisors were prepared and filled with Vitapex and randomly divided into five groups of 8 each. In Groups 1-4, a post space was created and filled with different restorative materials (Tetric® N-Ceram Bulk Fill, AeliteFlo, Filtek Z250 XT, and GC Fuji II LC® capsule), while Group 5 was kept filled with Vitapex as a control. Fracture resistance was measured using a universal testing machine at a 0.5-mm/min crosshead speed. The results were statistically analyzed and compared. RESULTS: The highest fracture resistance was recorded for GC Fuji II LC capsules [439.82 N] and control [423.37 N], while the lowest fracture resistance was recorded for Tetric® N Ceram Bulk Fill (239.91 N). A multiple comparison test showed that the Tetric® N-Ceram Bulk Fill had a significantly lower average value than AeliteFlo (P = 0.030), as well as a significantly lower average value than GC Fuji II LC® capsule (P = 0.001), and a significantly lower average value than the control group (P = 0.002). Multiple comparison tests showed no significant difference between Tetric® N-Ceram Bulk Fill and Filtek Z250 XT (P = 0.39). CONCLUSION: The fracture resistance of primary incisor root canals differs according to the material used for the intracanal posts. Three-millimeter intracanal posts in the primary incisors showed the highest fracture resistance for the teeth restored with GC Fuji II LC capsules and the control.

Effect of Whitening Toothpastes and Brushing on Microhardness of Esthetic Restorative Materials.

OBJECTIVE: Whitening toothpastes are widely used. Hence, it is important to understand their effect on the surface properties of restorative materials. To evaluate the effect of three over-the-counter whitening toothpastes and toothbrushing simulation on microhardness of three restorative materials. STUDY DESIGN: Forty cylindrical (10×2mm) specimens were prepared from each restorative material and randomly assigned into four groups/10 each according to the whitening toothpastes used and distilled water (control). All specimens were measured for microhardness (Baseline-T1). The specimens were brushed with a soft brush using an in vitro tooth-brushing simulator with the assigned whitening toothpaste using the same setting for brushing cycles/load for all groups. Specimens were then measured for microhardness (T2) similar to baseline. RESULTS: The highest (mean±SD) microhardness after application of the whitening toothpastes and brushing was recorded for Intense White and Filtek Z250 XT (127.6±1.8), followed by Optic White and Fuji ll LC (73.9±0.9) and Optic White and Photac Fill (72.7±1.3). There was statistically significant difference for microhardness between pre- and post-application of the whitening toothpastes and brushing for all tested restorative materials (P=0.0001). The microhardness of Filtek Z250XT with 3D White post-application of the whitening toothpastes and brushing was lowest compared to other toothpastes and control (P=0.0001). CONCLUSION: Microhardness increased after application of the whitening toothpastes and toothbrushing simulation for all combination of tested restorative materials and whitening toothpastes. The microhardness of FIiltek Z250XT with 3D White post-application of the whitening toothpastes and brushing was lowest compared to other toothpastes and control.

Effect of Remineralizing Agents on Bond Strength of Resin-Composites to Primary Enamel.

Aim: The purpose of this in vitro investigation was to assess the effect of three remineralizing agents (Voco Remin Pro®, Uncle Harry's remineralization kit, Sunshine remineralization gel) on the shear bond strengths of two resin-composites (Tetric® N-Ceram and Filtek™ Z250 Universal Restorative) to enamel of primary molars. Study design: Ninety-six enamel specimens were prepared and randomly distributed to eight groups according to the control, remineralizing agents, and resin composite used. Shear bond strength was measured at a crosshead speed of 0.5 mm/min and the type of bond failure was recorded. Results: The highest shear bond strength (Mean+SD) in MPa was for Tetric® N-Ceram/control [21.06+1.68] while the lowest was for Filtek™ Z250/Sunshine remineralization gel [11.98+1.46]. Tukey HSD Post Hoc Tests showed significant difference between Tetric® N-Ceram/control and all other groups (p=0.0001) except Filtek™ Z250/control. In addition, there was significant difference between Filtek™ Z250/control and all other groups (p=0.0001) except Tetric® N-Ceram/control and Tetric® N-Ceram/Uncle Harry's remineralization kit. Mode of failure was cohesive (9.38%), adhesive (55.21%), and mixed (35.42%). Conclusions: The three tested remineralizing agents affect shear bond strength of the tested resin-composites to enamel of primary teeth. In general, shear bond strength values were acceptable. Mode of failure was mostly adhesive.

Effects of fruit drinks on surface roughness of two esthetic restorative materials.

OBJECTIVES: Restorative materials may be exposed in the oral cavity to chemical agents found in beverages, which may lead to their biodegradation. The purpose of this in vitro study was to evaluate the effect of two fruit drinks commonly used by children on surface roughness of two esthetic restorative materials. MATERIALS AND METHODS: One resin composite (RC), one resin-modified glass ionomer (RMGI) and two fruit drinks (orange and cocktail) were used in this study. Specimens (n=20) of each material were fabricated against Mylar strip. Baseline measurements of surface roughness were recorded for each group using noncontact surface profilometer. Each specimen was placed in the tested fruit drinks for 24 hours and then surface roughness was recorded. RESULTS: The mean (±SD) surface roughness of RC before and after immersion in orange and cocktail were 0.04±0.02, 0.12±0.05, 0.06±0.03 and 0.11±0.06, respectively and for RMGI were 0.72±0.14, 0.60±0.19, 0.56±0.11, and 0.52±0.15. For RC there was significant difference between surface roughness (Sa) before and after immersion in orange and cocktail (P<0.05). For RMGI, there was significant difference between surface roughness before and after immersion in orange (P<0.05), but no significant difference before and after immersion in cocktail (P>0.05). CONCLUSIONS: The surface roughness of the RC and RMGI examined showed a significant change in the surface roughness after immersion for 24 hours in the tested fruit drinks.

Effect of different intermediary bases on microleakage of a restorative material in Class II box cavities of primary teeth.

INTRODUCTION: The aim of this in vitro study was to assess and compare the effect of different intermediary bases on microleakage between tooth and a nanocomposite interface in Class II box cavities in primary teeth. METHODS: Standard Class II box cavities were prepared in 52 primary molars and randomly divided into 9 groups according to the intermediary base used (Multicore Flow, Fuji II LC, SDR, Smart Dentin Replacement, and Biodentine). All specimens were subjected to thermocycling and prepared for microleakage testing and evaluation. RESULTS: There was significant difference in the mean ranks of microleakage between the 9 groups, which was observed in the gingival side (p<0.0001) and the occlusal side (p<0.0001). The mean ranks microleakage was significantly higher with experimental SDR, experimental Multicore Flow, and positive control materials when compared with the other 6 groups. The microleakage mean ranks were statistically significantly lower in experimental Fuji II LC, experimental Biodentine, and all negative control groups when compared with the other 3 groups. CONCLUSIONS: Microleakage is affected by the application of intermediate material. Experimental Biodentine and Fuji II LC showed the lowest microleakage while experimental SDR and experimental Multicore Flow showed the highest microleakage.

Shear bond strength of different dentin substitute restorative materials to dentin of primary teeth.

This in vitro investigation compared the shear bond strength (SBS) of four dentin substitute/replacement materials to caries-affected dentin of primary teeth. Dentin surfaces were randomly divided into four groups of 12 each according to the material used as follows: SDR/Smart Dentin Replacement, Biodentine, Multicore Flow, and Fuji II LC. The SBS was measured and failure modes were determined. There was a statistically significant difference in the mean values of SBS among the four materials (F=741.523, p<0.0001). The mean values of SBS of SDR were statistically significantly higher followed by Multicore Flow compared to the other groups. The mean values of the four materials were significantly different from each other in all combinations of pairs of four materials. The SBS between the four dentin substitute/replacement materials to dentin of primary teeth was significantly different. The highest SBS was for SDR followed by Multicore Flow then Fuji II LC and the lowest was for Biodentine.

Effects of the preparation technique and type of material on the penetrability of sealants.

The purpose of this in vitro study was to compare the penetration of 2 resin-based and 2 glass ionomer sealants into fissures after either conventional or mechanical preparation. All the materials placed in the conventionally prepared and mechanically prepared fissures penetrated the fissures beyond the standard (0.5-mm) reference line used in this study. For 1 glass ionomer sealant, the number of specimens showing complete penetration of sealant was significantly greater (P < 0.05) in mechanically prepared fissures than in conventionally prepared ones. No significant differences were found between mechanically and conventionally prepared fissures for the other sealants.

Dental students' knowledge of oral health for persons with special needs: a pilot study.

OBJECTIVES: The purpose of this pilot study was to assess the knowledge and awareness of dental students with respect to oral health care of the person with special health care needs (SHCN) and evaluate effectiveness of an education program on improving their knowledge. METHOD: An evaluation consisting of a questionnaire was answered before and immediately after a 30-minute educational presentation in the form of a DVD that includes a PowerPoint and a video of oral health care for individuals with SHCN. The questionnaire was based on the materials and information presented in the DVD and included 26 questions (true/false/I do not know). RESULTS: The mean (± SD) score on the pretest was 10.85 (± 5.20), which increased to 16.85 (± 5.47) on the posttest. This difference was statistically significant (P < 0.001). Forty percent of the students surveyed reported that they were very satisfied with the educational part of the presentation, while 50% were somewhat satisfied. Thirty percent of students expressed that the educational intervention used is very effective. CONCLUSIONS: Viewing the educational intervention was effective in informing the sophomore students and providing them with instructive basic information on person with SHCN. Dental colleges should increase students' knowledge, training, and exposure to individuals with SHCN.