Purpose: The purpose of this study was to evaluate the influence of various contaminants on the apical sealing ability and microhardness of mineral trioxide aggregate (MTA) in extracted teeth ex vivo. Methods: The root canals of 51 single-rooted human teeth were prepared and fi11ed with laterally condensed guttapercha cones and a sealer After root surface coating, apicoectomy ancl preparation of apical cavities, the teeth were randomly divided into 5 groups. Group 1 was contarninated with distMed water (control), group 2 with saline solution, group 3 with adrenalin solution, group 4 with blood, and group 5 with EDTZA solution. After filling with MZA, the teeth were subjected to a leakage test. The teeth samples were then bisected and subjected to a microhardness test, and observed by stereoscopy and scanning electron microscopy Results: A hermetic seal was observecl morphologically in group 1. Howeve; partial sealing and gaps between dentin and MTZA or lacunae in MTA were observed in groups 2-5. Group 1 showed significantly less leakage than the other groups, but there was no significant difference among the experimental groups, The microhardness of group 5 was significant]y Iess than that of group 1. Conclusion: The results suggested that contamination of MZA while setting decreased the sealing ability of M[[IA.
One of the most challenging task in closing anterior diastema is avoiding “black triangle”between the teeth. This paper reports a case that the closure of diastema in anterior teeth could be successfully accomplished using direct adhesive restorations and gingival recontouring. The traditional technique using Mylar strip was modified to increase the emergence profile with natural contours at the gingival-tooth interface. Mylar strip was extended out of the sulcus by approximately 1 mm high from the gingival margin, and a small cotton pellet was used to provide the emergence contour. This modified approach is acceptable for the clinical situation. [J Kor Acad Cons Dent 2011;36(6):515-520.]
Objectives: This in vitro study investigated whether short-term application of calcium hydroxide in the root canal system for 1 and 4 wk affects the fracture strength of human permanent teeth. Materials and Methods: Thirty two mature human single rooted mandibular premolars in similar size and dentin thickness without decay or restorations were hand and rotary instrumented and 16 teeth vertically packed with calcium hydroxide paste and sealed coronally with caviton to imitate the endodontic procedure and the other 16 teeth was left empty as a control group. The apicies of all the samples were sealed with resin, submerged in normal saline and put in a storage box at 37℃ to mimic the oral environment. After 1 and 4 wk, 8 samples out of 16 samples from each group were removed from the storage box and fracture strength test was performed. The maximum load required to fracture the samples was recorded and data were analysed statistically by the two way ANOVA test at 5% significance level. Results: The mean fracture strengths of two groups after 1 wk and 4 wk were similar. The intracanal placement of calcium hydroxide weakened the fracture strength of teeth by 8.2% after 4 wk: an average of 39.23 MPa for no treatment group and 36.01 MPa for CH group. However there was no statistically signif- icant difference between experimental groups and between time intervals. Conclusions: These results suggest that short term calcium hydroxide application is available during endodontic treatment. ABSTRACT 1 Shin EJ, Dental school student, Chonnam National University School of dentistry,
Objectives The purpose of this experiment was to evaluate four different polishing systems of their polishability and polishing time. Materials and Methods 4 mm diameter and 2 mm thickness Teflon mold was made. Z-250 (3M ESPE) hybrid composite resin was slightly overfilled and pressed with slide glass and cured with Optilux 501 for 40 sec each side. Then the surface roughness (glass pressed: control group) was measured with profilometer. One surface of the specimen was roughened by #320 grit sand paper and polished with one of the following polishing systems; Sof-Lex (3M ESPE), Jiffy (Ultradent), Enhance (Dentsply/Caulk), or Pogo (Dentsply/Caulk). The surface roughness and the total polishing time were measured. The results were analyzed with one-way ANOVA and Duncan's multiple range test. Results The surface roughness was lowest in Pogo, and highest in Sof-Lex. Polishing times were shortest with Pogo, and followed by the Sof-Lex, Enhance and Jiffy. Conclusions One-step polishing system (Pogo) is very effective to get the smooth surface in a short time, therefore it can be recommended for final polishing system of the restoration.
Objectives: The purpose of this study was to compare the microshear bond strength (SBS) and bonding interfaces of two-step total-etching and self-etching adhesive systems to three etch types of dentin either the acid etched, laser etched or laser and acid etched. Materials and Methods: The occlusal dentinal surfaces of thirty human molars were used. They were divided into six groups: group 1, 37% + Single Bond 2 (3M ESPE); group 2, Er:YAG laser (KEY Laser 3, KaVo) + Single Bond 2; group 3, Er:YAG laser + 37% + Single Bond 2; group 4, Clearfil SE Primer + Bond (Kuraray); group 5, Er:YAG laser + Clearfil SE Bond; group 6, Er:YAG laser + Clearfil SE Primer + Bond. The samples were subjected to SBS testing 24 hr after bonding. Also scanning microscopic evaluations were made on the resin-dentin interfaces of six specimens. Results: The SBS of group 2 was significantly lower than that of groups 1 and 3 in Single Bond 2 (p
Objectives: This study was aimed to determine the effects of temporary sealing materials on microtensile bond strength between resin-coated dentin and resin inlay and to compare the bonding effectiveness of delayed dentin sealing and that of immediate dentin sealing. Materials and Methods: The teeth were divided into 4 groups: group 1, specimens were prepared using delayed dentin sealing after temporary sealing with zinc oxide eugenol (ZOE); group 2, specimens were prepared using immediate dentin sealing and ZOE sealing; group 3, specimens were prepared using imme- diate dentin sealing and Dycal (Dentsply) sealing; group 4, specimens were prepared using immediately sealed, and then temporarily sealed with a resin-based temporary sealing material. After removing the temporary sealing material, we applied resin adhesive and light-cured. Then the resin inlays were applied and bonded to the cavity with a resin-based cement. The microtensile bond strength of the sectioned specimens were measured with a micro-tensile tester (Bisco Inc.). Significance between the specimen groups were tested by means of one-way ANOVA and multiple Duncan' s test. Results: Group 1 showed the lowest bond strength, and group 4 showed the highest bond strength ( p < 0.01). When temporary sealing was performed with ZOE, immediate dentin sealing showed a higher bond- ing strength than delayed dentin sealing ( p < 0.01). Conclusions: Based on these results, immediate dentin sealing is more recommended than delayed dentin sealing in bonding a resin inlay to dentin. Also, resin-based temporary sealing materials have shown the best result. (J Kor Acad Cons Dent 2011;36(5):419-424.) ABSTRACT
Objectives: Palatogingival groove is a developmental anomaly that starts near the cingulum of the tooth and runs down the cementoenamel junction in apical direction, terminating at various depths along the roots. While frequently associated with periodontal pockets and bone loss, pulpal necrosis of these teeth may precipitate a combined endodontic-periodontal lesion. This case presents a case of a lateral incisor anatomically complicated with palatogingival groove. Methods: Two patients with lesion associated with the palatogingival groove were chosen for this report. Palatogingival grooves were treated with different restoration materials with endodontic treatment. Conclusions: Maxillary lateral incisor with a palatogingival groove may occur the periodontal disease with pulpal involvement. Elimination of groove may facilitate the periodontal re-attachment and prevent the recurrence. [J Kor Acad Cons Dent 2011;36(3):238-242.]
Objectives: The purpose of this in vivo study was to investigate the microbial diversity in symptomatic and asymptomatic canals with primary endodontic infections by using GS FLX Titanium pyrosequencing. Materials and Methods: Sequencing was performed on 6 teeth (symptomatic, n = 3; asymptomatic, n = 3) with primary endodontic infections. Amplicons from hypervariable region of the small-subunit ribosomal RNA gene were generated by polymerized chain reaction (PCR), and sequenced by means of the GS FLX Titanium pyrosequencing. Results: On average, 10,639 and 45,455 16S rRNA sequences for asymptomatic and symptomatic teeth were obtained, respectively. Based on Ribosomal Database Project Classifier analysis, pyrosequencing iden- tified the 141 bacterial genera in 13 phyla. The vast majority of sequences belonged to one of the seven phyla: Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Proteo bacteria, Spirochetes, and Synergistetes . In genus level, Pyramidobacter, Streptococcus, and Leptotrichia constituted about 50% of microbial profile in asymptomatic teeth, whereas Neisseria, Propionibacterium, and Tessaracoccus were frequently found in symptomatic teeth (69%). Grouping the sequences in operational taxonomic units (3%) yielded 450 and 1,997 species level phylotypes in asymptomatic and symptomatic teeth, respectively. The total bacteria counts were significantly higher in symptomatic teeth than that of asymptomatic teeth ( p < 0.05). Conclusions: GS FLX Titanium pyrosequencing could reveal a previously unidentified high bacterial diver- sity in primary endodontic infections. (J Kor Acad Cons Dent 2011;36(6):498-505.) ABSTRACT
