IADR Abstract Archives
EDTA Application Time Effect on Compressive Strength of Human Dentin
Objectives: To determinate the effect of 17% EDTA application time on compressive strength of human radicular dentin
Methods: Experimental in vitro study. Protocol was approved by IRB. After a pilot study, sample size was calculated using a statistical formula. Thirty (30) human premolars extracted for orthodontic reasons were collected and stored in 0.9% saline solution for seven days. Clinical crowns were sectioned at cement-enamel junctions and teeth were randomly distributed into five groups of six teeth each: control group (without mechanical preparation and irrigation); and 4 experimental groups which were mechanically instrumented with a rotary system (ProTaper Next®, Denstply-Maillefer, Switzerland) and irrigated with 12 cc of 5.25% NaOCl at 40°C, Passive Ultrasonic Irrigation for 1 minute, 17% EDTA at different time periods (1, 3, 5 and 10 minutes) and final rinse with 70% ethyl alcohol. Root apical-middle sections (10 mm) of the five groups were removed and then remaining sections (6 mm length) were longitudinally sectioned into two equal segments resulting in a half truncated-cone shape specimen (12 specimens per group). They were observed using a stereomicroscope (STEMI 2000-C Zeiss®, Jena, Germany) in order to determinate the presence of cracks that could affect the mechanical properties evaluated. Compressive strength tests were performed (1,0mm/min crosshead speed) using the Universal Testing Machine (Instron® 2736-015, Norwood MA, USA). Statistical analysis was made using the ANOVA F test and Tukey, Scheffe, Duncan and Bartlett multiple comparison tests
Results: No statistical significant differences were observed when the five groups were compared (p>0.05). However, compressive strength of groups 3 and 5 showed the highest mean values (EDTA 3 min/167 MPa, EDTA 10 min/171 MPa, respectively). Control group reported the lowest compressive strength (155 MPa)
Conclusions: Experimental irrigation protocols evaluated in this in vitro study did not affect significantly the compressive strength of human radicular dentin
Methods: Experimental in vitro study. Protocol was approved by IRB. After a pilot study, sample size was calculated using a statistical formula. Thirty (30) human premolars extracted for orthodontic reasons were collected and stored in 0.9% saline solution for seven days. Clinical crowns were sectioned at cement-enamel junctions and teeth were randomly distributed into five groups of six teeth each: control group (without mechanical preparation and irrigation); and 4 experimental groups which were mechanically instrumented with a rotary system (ProTaper Next®, Denstply-Maillefer, Switzerland) and irrigated with 12 cc of 5.25% NaOCl at 40°C, Passive Ultrasonic Irrigation for 1 minute, 17% EDTA at different time periods (1, 3, 5 and 10 minutes) and final rinse with 70% ethyl alcohol. Root apical-middle sections (10 mm) of the five groups were removed and then remaining sections (6 mm length) were longitudinally sectioned into two equal segments resulting in a half truncated-cone shape specimen (12 specimens per group). They were observed using a stereomicroscope (STEMI 2000-C Zeiss®, Jena, Germany) in order to determinate the presence of cracks that could affect the mechanical properties evaluated. Compressive strength tests were performed (1,0mm/min crosshead speed) using the Universal Testing Machine (Instron® 2736-015, Norwood MA, USA). Statistical analysis was made using the ANOVA F test and Tukey, Scheffe, Duncan and Bartlett multiple comparison tests
Results: No statistical significant differences were observed when the five groups were compared (p>0.05). However, compressive strength of groups 3 and 5 showed the highest mean values (EDTA 3 min/167 MPa, EDTA 10 min/171 MPa, respectively). Control group reported the lowest compressive strength (155 MPa)
Conclusions: Experimental irrigation protocols evaluated in this in vitro study did not affect significantly the compressive strength of human radicular dentin
