C o p y r i g h t b y N o t f o r Q u i n t e s s e n c e Not for Publication C hronic renal failure (CRF) is defined as a progressive de- cline in renal function associated with a reduced glomerular filtration rate (GFR) as measured clinically by the creatinine clearance rate. The incidence of CRF has been re- ported to be 337, 90, 107, and 200 per million population in the USA, Australia, New Zealand, and Egypt, respectively. 7 Dental changes including enamel hypoplasia of the primary and permanent teeth with or without brown discoloration 2 and narrowing or calcification of the pulp chamber of teeth of adults with CRF 5 have been reported. In addition, char- acteristic changes analogous to those seen in bone were de- tected in dentin of erupted teeth in patients with CRF. 1,11 Considering the preceding information and because the suc- cess of modern esthetic restoratives is greatly dependent on the quality and the performance of their bonds to dental sub- strates, 3 deteriorated or weak bonding of these materials to tooth tissues of uremic patients could be expected. This hy- pothesis has not been hitherto confirmed or even dismissed in spite of the recent improvements in the chemistry of ad- hesive systems that have succeeded to a great extent in off- setting the difficulties associated with bonding to different Bonding of Resin Composite to Tooth Structure of Uremic Patients Receiving Hemodialysis: Shear Bond Strength and Acid-etch Patterns Salah Hasab Mahmoud a /Mohamed Abdel kader Sobh b /Ahmed Ragheb Zaher c / Mohamed Hamed Ghazy d /Khalid Mohamed Abdel Aziz e Purpose: To investigate the influence of uremia on the shear bond strength (SBS) of composite resin to enamel and dentin substrates with assessment of the micromorphological pattern of etched enamel and dentin surfaces using atomic force microscopy (AFM). Materials and Methods: A total of 44 natural molars was collected from healthy individuals (n = 22 molars) and ure- mic patients (n = 22 molars). Each set of teeth was then divided into 2 equal subsets (n = 11 molars) relative to the bonding substrate to be tested. In each subset, the surfaces of 7 molars were flattened and polished up to 2000-grit roughness using wet silicon carbide (SiC) abrasive papers. A three-step adhesive was used to bond Tetric Ceram com- posite buildups to the prepared tooth surfaces. All specimens were thermocycled before they were stressed in shear using a universal testing machine. Fractured specimens were stereomicroscopically examined to detect the mode of bond failure. In the remaining 4 molars, enamel and dentin specimens were prepared for AFM examination to assess the micromorphological patterns of acid-etched surfaces. Results: The mean bond strength values in MPa to enamel (22.40 ± 4.30) and dentin (17.97 ± 4.65) of teeth of healthy individuals were significantly different (p < 0.001) from those to enamel (12.40 ±2.81) and dentin (7.83 ± 2.05) of teeth of uremic patients. Most of the tested enamel specimens showed a mixed type of bond failure, but the adhesive type was predominant with dentin specimens. AFM examinations revealed a shallow etching pattern for ure- mic enamel and dentin specimens compared to those of healthy individuals. The mean roughness average (Ra) val- ues after etching of healthy enamel (238.0 ± 4.65) and dentin (267.0 ± 4.79) were significantly different (p < 0.001) from those to etched uremic enamel (111.0 ± 5.24) and dentin (143.0 ± 2.16). Conclusion: Uremia adversely affects bonding of composite resin to enamel and dentin and confers an altered micro- morphological etching pattern. Keywords: uremia, resin composite, shear bond strength, enamel and dentin, acid-etch pattern. J Adhes Dent 2008; 10: 335-338. Submitted for publication: 15.04.08; accepted for publication: 19.07.08. Vol 10, No 5, 2008 335 a Associate Professor and Head of Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. b Professor and Head of Nephrology Department, Urology and Nephrology Cen- ter, Mansoura University, Mansoura, Egypt. c Associate Professor, Department of Oral Biology, Faculty of Dentistry, Man- soura University, Mansoura, Egypt. d Associate Professor, Department of Conservative Dentistry, Faculty of Den- tistry, Mansoura University, Mansoura, Egypt. e Lecturer, Department of Dental Biomaterials, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt. Correspondence: Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. Tel: +2-010-7932333, Fax: +2-050- 226-0173. e-mail: dr_salahhasab@yahoo.com