Retention strengths of five luting cements on prefabricated dowels after root canal obturation with a zinc oxide/eugenol sealer: 1. Dowel space preparation/cementation at one week after obturation.
OBJECTIVE
This investigation examined the effect of 5 different cements on the retention strength of prefabricated endodontic dowels placed into root canals previously obturated with gutta percha and a zinc oxide/eugenol (ZOE) sealer.


METHODS
Ninety-six single-rooted teeth were decoronated, filed, cleaned, sequentially shaped, and divided into 6 groups of 16 specimens each. Five of the groups were then obturated with gutta percha and a ZOE sealer. One group was not obturated and served as the control group. Dowel space preparation and dowel cementation for all groups were completed 1 week later. Ten-mm deep dowel spaces were prepared using size 6 Gates Glidden drills. Size 5 Paraposts were then cemented with 5 different cements: Panavia 21 for group 1 (unobturated controls) and group 2; Ketac-Cem glass ionomer for group 3; Fleck's zinc phosphate for group 4; Parapost (composite) Cement for group 5; and C&B Metabond 4-META for group 6. After 48 hours, the dowels were removed using a universal testing machine in tensile mode at 1 mm min(-1).


RESULTS
The following results were found (all values in kg): group 1 (controls; Panavia 21) mean = 61.81, 95% CI = +/-8.65; group 2 (Panavia 21), mean=43.15, 95% CI = +/-7.81; group 3 (Ketac-Cem), mean =34.45, 95% CI = +/-4.93; group 4 (zinc phosphate), mean = 25.07, 95% CI = +/-5.03; group 5 (Parapost Cement), mean = 24.99, 95% CI = +/-5.35. None of the group 6 (C&B Metabond) specimens developed measurable bond strengths, so this group was excluded from parametric statistical analyses. An analysis of variance (ANOVA) showed a significant effect of group; pairwise multiple comparison procedures (Tukey test) showed that group 1 (controls) had significantly greater retention than all other groups (p <0.001); group 2 (Panavia 21) had significantly greater retention than groups 4 (zinc phosphate) and 5 (Parapost cement) (p <0.001). None of the other pairwise comparisons were statistically different.


CONCLUSIONS
Paraposts cemented with Panavia 21 in unobturated root canals exhibited significantly higher retention than Paraposts luted with Panavia 21 and 4 different cements into dowel spaces prepared 1 week after obturation with gutta percha/ZOE sealer (p <0.001). Among the obturated groups, Panavia 21 cement (group 2) demonstrated significantly greater retention of Paraposts than zinc phosphate (group 4) and Parapost composite (group 5) cements (p <0.001). Ketac-Cem glass ionomer cement (group 3) had intermediate retention values that were not statistically different than those of groups 2, 4, and 5 (p >0.05). The 4-META cement, C&B Metabond, failed to polymerize.
Hagge
Mark S
MS
University of the Pacific School of Dentistry, San Francisco, CA 94115, USA. mhagge@sf.uop.edu
Wong
Ralan D M
RD
Lindemuth
James S
JS
D000704:Analysis of Variance; D001896:Boron Compounds / Q000737:chemistry; D002484:Cementation; D003188:Composite Resins / Q000737:chemistry; D016001:Confidence Intervals; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D017268:Dental Prosthesis Retention; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005500:Follow-Up Studies; D005899:Glass Ionomer Cements / Q000737:chemistry; D006171:Gutta-Percha / Q000737:chemistry; D006801:Humans; D008277:Magnesium Oxide / Q000737:chemistry; D016555:Matched-Pair Analysis; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation; D013314:Stress, Mechanical; D013718:Tensile Strength; D019231:Tooth Preparation, Prosthodontic / Q000295:instrumentation; D015034:Zinc Oxide / Q000737:chemistry; D015035:Zinc Oxide-Eugenol Cement / Q000737:chemistry*; D015036:Zinc Phosphate Cement / Q000737:chemistry
D001896:Boron Compounds; D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; C061504:Flecks; D005899:Glass Ionomer Cements; D008689:Methacrylates; D008768:Methylmethacrylates; C093719:Panavia TPN-S; D010710:Phosphates; D011076:Polycarboxylate Cement; D019279:Resin Cements; D012387:Root Canal Filling Materials; D015035:Zinc Oxide-Eugenol Cement; D008277:Magnesium Oxide; C034139:4-methacryloxyethyltrimellitic acid anhydride; D015036:Zinc Phosphate Cement; C040235:Ketac-cem; D006171:Gutta-Percha; C049495:Super-bond; D015034:Zinc Oxide