Accuracy of intraoperative cultures in primary total hip arthroplasty

The aim of this investigation was to assess the diagnostic accuracy of intraoperative cultures for the early identification of patients who are at risk of infection after primary total hip arthroplasty. Four or six swabs were obtained immediately before the wound closure in 263 primary total hip replacements. Patients with a maximum of one positive culture were denoted as patients with a normal profile and did not receive any treatment. Patients with two or more positive cultures, with the same organism identified, were denoted as patients with a risk profile and received treatment with a specific antibiotic as determined by the antibiogram for six weeks. The follow-up ranged from a minimum of one year to five years and eleven months, concentrating on the presence or absence of infection, which was defined as discharge of pus through the surgical wound or as a fistula at any time after surgery. The accuracy of this procedure ( number of cases correctly identified in relation to the total number of cases) in the group of 152 arthroplasties in which 4 swabs per patient were collected was 96%. In the group of 111 arthroplasties in which 6 swabs per patient were collected the accuracy was 95.5%. We conclude that the collection of swabs under the conditions described is a method of high accuracy ( above 95%) for the evaluation of risk of infection after primary total hip arthroplasty.

Effect of oxalate desensitizers and dentin moisture during total-etch bonding

Purpose: To evaluate the effect of oxalate during total-etch bonding, under different dentin moisture conditions, over time. The null hypothesis tested was that microtensile bond strength (mu TBS) was not affected by oxalate treatment and dentin moisture during two evaluation periods. Methods: Extracted human third molars had their mid-coronal dentin exposed flat and polished with 600-grit SiC paper. The surfaces were etched with 35% phosphoric acid for 15 seconds, washed and blot dried. After etching, a 3% potassium oxalate gel was applied for 120 seconds, except for the control group (no desensitizer). The surface was then washed and left moist (Wet bonding) or air-dried for 30 seconds (Dry bonding). The surfaces were bonded with: (I) two 2-step etch-and-rinse adhesives: Single Bond (SB); Prime & Bond NT (PBNT) and (2) one 3-step etch-and-rinse adhesive: Scotchbond Multi Purpose (SBMP). Composite buildups were constructed incrementally with Tetric Ceram resin composite. Each increment was cured for 40 seconds. After storage in water for 24 hours or 1 year at 37 C, the specimens were prepared for mu TBS testing with a cross-sectional area of approximately 1 mm(2). They were then tested in tension in an Instron machine at 0.5 mm/minute. Data were analyzed by ANOVA and Student-Newman-Keuls at alpha = 0.05. Results: Application of potassium oxalate had no significant effect on the bond strengths of SBMP and PBNT, regardless of the surface moisture condition (P > 0.05). Conversely, reduced bond strengths were observed after oxalate treatment for SB in both moisture conditions, that being significantly lower when using a dry-bonding procedure (P < 0.05). Lower bond strength was obtained for PBNT when a dry-bonding technique was used, regardless of the oxalate treatment (P < 0.05). After aging the specimens for 1 year, bond strengths decreased. Smaller reductions were observed for SBMP, regardless of moisture conditions. For the WB technique, smaller reductions after 1 year were observed without oxalate treatment for SB and after oxalate treatment for PBNT. (Am J Dent 2010;23:137-141).