Shear bond strength of ceramic brackets with different base designs to feldspathic porcelains.
OBJECTIVE
To test the hypothesis that the there is no difference between the shear bond strengths of different base designs of ceramic brackets bonded to glazed feldspathic porcelains.


METHODS
Forty glazed feldspathic porcelain specimens (15 mm in diameter and 1.5 mm in thickness) were prepared and divided into 4 groups (n = 10). Ten pieces of each group of different ceramic bracket base designs (beads, large round pits, and irregular base) and one group of stainless steel brackets (served as a control) were bonded to glazed feldspathic porcelains under a 200 gram load. Then all samples were subjected to shear bond strength evaluation with a universal testing machine at a crosshead speed of 0.2 mm/min. Data were analyzed through one-way ANOVA and Tukey's HSD test at a .05 significance level. The mode of failure after debonding was examined under a stereoscope.


RESULTS
This study revealed that the beads base design had the greatest shear bond strength (24.7 +/- 1.9 MPa) and was significantly different from the large round pits base (21.3 +/- 2 MPa), irregular base (19.2 +/- 2.0 MPa), and metal mesh base (15.2 +/- 2.4 MPa). The beads base design had 100% porcelain-adhesive failure, the large round pits had 100% bracket-adhesive failure, and the irregular base design had 70% combination failure and 30% porcelain-adhesive failure.


CONCLUSIONS
The hypothesis is rejected. The various base designs of metal and ceramic brackets influence bond strength to glazed feldspathic porcelain, but all should be clinically acceptable.
Samruajbenjakul
Buncha
B
Department of Preventive Dentistry, Prince of Songkla University, Songkhla, Thailand.
Kukiattrakoon
Boonlert
B
D000134:Acid Etching, Dental; D000538:Aluminum Silicates / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D000538:Aluminum Silicates; D003722:Dental Alloys; D003764:Dental Materials; D010756:Phosphoric Acids; D017680:Potassium Compounds; D019279:Resin Cements; C045637:System 1 plus; C080305:Vita VMK 595; D003776:Dental Porcelain; C016447:feldspar; D013193:Stainless Steel; C030242:phosphoric acid