oxalates and Tooth-Fractures

This study investigated whether the tubular occluding effect of oxalate desensitizer (OX) during adhesive cementation (three resin cements) influenced fracture resistance of teeth restored with adhesive inlays.. Ninety intact maxillary premolars were randomly divided into 9 groups of 10 each. The two control groups were Gr 1, intact teeth and Gr 2, mesio-occlusodistal preparation only. In six experimental groups, the composite inlays were cemented with ED Primer II/Panavia F 2.0, Excite DSC/Variolink II, and One-Step Plus/Duolink according to manufacturers' instructions (Groups 3, 5, and 7, respectively) or with OX during cementation (Groups 4, 6, and 8, respectively). In Group 9, inlays were cemented with a resin cement without adhesive system. After thermocycling, fracture strength was tested. The data were analyzed using two-way and one-way ANOVA and LSD post hoc tests (α = 0.05).. Fracture resistance of the six groups were significantly affected by OX (p = 0.002) but not by the resin cement type (p > 0.05). The interaction of the two factors was statistically significant (p = 0.052). A statistically significant difference between all groups was found (p < 0.001). The mean fracture resistances (N) were: Gr1 = 1168 ± 157,(a) Gr2 = 360 ± 110,(d) Gr3 = 1026 ± 188,(b) Gr4 = 887 ± 143,(c) Gr5 = 1007 ± 132,(b) Gr6 = 810 ± 164,(c) Gr7 = 1033 ± 218,(a) Gr8 = 955 ± 147,(ab) Gr9 = 780 ± 86(c) (groups with the same superscript letter indicate statistical similarity).. Combining an OX with three resin cements had a significant negative effect on the fracture resistance of premolars restored with composite inlay cemented with Panavia F2.0 and Variolink II, but it had no significant effect when cemented with Duolink.

Topics: Aluminum Oxide; Bicuspid; Cementation; Composite Resins; Dental Cavity Preparation; Dental Etching; Dental Materials; Dental Restoration Failure; Dentin; Dentin Desensitizing Agents; Dentin-Bonding Agents; Humans; Inlays; Materials Testing; Methacrylates; Oxalates; Random Allocation; Resin Cements; Surface Properties; Temperature; Time Factors; Tooth Fractures

A method is described, by which the fracture strength of bonded, previously fractured incisors can be measured. The study employed incisors from sheep, which could be obtained in suitable numbers and with limited variation in size. The incisors were fractured parallel to the incisal edge. The mean fracture area +/- SD of central incisors was 8.45 +/- 0.89 mm2 and of lateral incisors 6.50 +/- 0.64 mm2. The enamel area constituted about 30% of the total fracture area. Acid etching of the enamel and bonding of the fractures with an unfilled resin yielded a fracture strength, which was approximately 38% of the fracture strength of fractured teeth restored with acid etching of enamel, Gluma treatment of dentin and bonding with the unfilled resin. Teeth restored in this way, but using the dentin bonding agent Tenure or Scotchbond2 instead of Gluma, exhibited mean fracture strengths which were not significantly different from that obtained when Gluma was employed as the bonding agent. The mean fracture strength by using one of the three bonding agents in combination with acid etching of enamel was about 8 MPa, which is approximately 50% of the fracture strength of intact teeth.

Topics: Acid Etching, Dental; Animals; Dental Bonding; Dental Cements; Dental Stress Analysis; Glutaral; Materials Testing; Nitrates; Nitric Acid; Oxalates; Polymethacrylic Acids; Resin Cements; Sheep; Tensile Strength; Tooth Fractures

Measurements of fracture strengths of incisors from sheep, previously fractured and then restored by reattaching the fragments with a light-curable resin, revealed that pretreatment of the fracture surfaces with dentin bonding agents such as Gluma, Tenure or Scotchbond2 and acid-etching of the enamel, gave values of about half the fracture strength of intact teeth. Measurements furthermore demonstrated that pretreatment by a combination of dentin bonding agents and acid-etching of the enamel yielded higher fracture strengths of the restored teeth, than that of teeth restored using only one of the two pretreatments. Fractured incisors, restored by Gluma-treatment of the dentin, acid-etching of the enamel and fragment-bonding with a light-curable resin, were further restored with porcelain veneers after preparation. Fracture strength measurements of such restored teeth revealed strength not significantly different from that of intact teeth. It is suggested that such restorations, could have a reasonably long period of function clinically.

Topics: Acid Etching, Dental; Dental Bonding; Dental Cements; Dental Veneers; Glutaral; Humans; Incisor; Nitrates; Nitric Acid; Oxalates; Polymethacrylic Acids; Resin Cements; Tooth Fractures