Clinical evaluation of 15% carbamide peroxide on the surface microhardness and shear bond strength of human enamel.
OBJECTIVE
This clinical evaluation compared a neutral sodium fluoridated whitening product to a neutral non-fluoridated whitening product in terms their effects on human enamel surface microhardness (SMH) and human enamel/resin composite shear bond strength (SBS) following various treatment times.


METHODS
Subjects were evaluated for enamel SMH and enamel/resin SBS following 15% carbamide peroxide (CP) with and without potassium nitrate and fluoride (PF). Twenty subjects (80 first or second premolars), who were treatment-planned for premolar extraction due to orthodontic therapy, were allocated into two groups, A and B. Group A received 15% CP, while Group B received 15% CP with PF. Each patient had a control tooth, a 14-day treatment + 14-day recovery tooth, a 14-day treatment + no recovery tooth and a 4-day + no recovery tooth. Each tooth was further divided into two testing surfaces; the facial surface was used for SMH, while the lingual surface was used for SBS.


RESULTS
The results of this study determined that there was no statistically significant difference between the effects of the two products on SMH and enamel/resin SBS. Additionally, there was no statistically significant difference between the treatment specimens compared to the controls in terms of SMH. However, there was a significant difference between the treatment groups compared to the controls in terms of enamel/resin SBS.


CONCLUSIONS
Within the limitations of this clinical study, 15% CP with and without PF does not seem to alter the SMH of human enamel. However, 15% CP with and without PF significantly reduced enamel/resin SBS immediately following tooth whitening therapy, up to 14 days post-treatment.
Metz
Michael J
MJ
Indiana University School of Dentistry, Indianapolis, IN, USA. michael.metz@med.navy.mil
Cochran
Michael A
MA
Matis
Bruce A
BA
Gonzalez
Carlos
C
Platt
Jeffrey A
JA
Pund
Melvin R
MR
D000293:Adolescent; D000077463:Carbamide Peroxide; D002327:Cariostatic Agents / Q000627:therapeutic use; D002648:Child; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects* / Q000648:ultrastructure; D004338:Drug Combinations; D005260:Female; D006244:Hardness; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage / Q000627:therapeutic use; D016877:Oxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D010545:Peroxides / Q000008:administration & dosage / Q000627:therapeutic use*; D017680:Potassium Compounds / Q000008:administration & dosage / Q000627:therapeutic use; D011446:Prospective Studies; D033081:Shear Strength; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000627:therapeutic use; D013314:Stress, Mechanical; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use
D002327:Cariostatic Agents; D003188:Composite Resins; D004338:Drug Combinations; D009566:Nitrates; D016877:Oxidants; D010545:Peroxides; D017680:Potassium Compounds; D000077463:Carbamide Peroxide; D014508:Urea; D012969:Sodium Fluoride; C023844:potassium nitrate