tetracycline and 3-5-xylenol

This study analyzed the effect of the platelet count in platelet-rich plasma (PRP) on bone regeneration in vivo. Twenty male New Zealand white rabbits were used. PRP was produced using the Platelet Concentrate Collection System (PCCS) (3i, Miami, FL, USA). After inducing ketamine-xylazine anaesthesia, a self-tapping titanium screw (Branemark MK III TiUnite, 3.75 x 7 mm) was inserted in each distal femur; the femurs were randomized so that one side was treated with PRP while the other (control) was not. Intravital fluorochrome staining was performed on days 1, 7 (1.5 ml of 2% doxycycline/kg bodyweight), 14 (6% xylenol orange, 1.5 ml/kg), and 21 (1% calcein green, 5 ml/kg). Animals were euthanized on day 28 (n = 20). Specimens were prepared for histomorphological evaluation according to Donath and Breuner [J. Oral Pathol. 11 (1982) 318]. Comparing the bone regeneration (fluorochrome staining) in the 4-week implants (n = 19), the only significant difference (sign test, P = 0.004) was seen with intermediate platelet concentrations (n = 9,503,000-1,729,000 platelets/microl PRP). There were no differences in the bone/implant contact rates between the test and the control side among the three groups. The platelet concentration required for a positive PRP effect on bone regeneration seems to span a very limited range. Advantageous biological effects seem to occur when PRP with a platelet concentration of approximately 1,000,000/microl is used. At lower concentrations, the effect is suboptimal, while higher concentrations might have a paradoxically inhibitory effect. On the other hand, the effect of this type of platelet concentrate was not beneficial to accelerate the osseointegration of enosseous dental implants.

Topics: Animals; Blood Platelets; Bone Regeneration; Bone Transplantation; Femur; Fluoresceins; Implants, Experimental; Male; Plasma; Platelet Count; Rabbits; Random Allocation; Staining and Labeling; Tetracycline; Xylenes

Substances that bind calcium are given to determine where and how fast bone is forming. Several vital dyes are used (tetracycline, calcein, alizarin, xylenol), but it is not known whether the histomorphometric results they provide are equivalent. This work tests whether different fluorochrome labels give the same results when they are quantitatively measured. Twelve-week-old rats (n = 58) were divided into six groups and given double labels IP of calcein, tetracycline HCl, alizarin complexone, or xylenol using a 1-7-1 scheme. Two other groups received either calcein followed by tetracycline, or tetracycline followed by calcein. Our results show that (a) tetracycline hydrochloride leads to a significant underestimation of mineralizing surface when given as the second label, probably because of its weak fluorescence; (b) there were no differences among any of the non-tetracycline labels for any of the histomorphometric measurements; (c) there was no evidence of osteoblast suppression with any label; and (d) there was no evidence that tetracycline caused increased osteoblast resting periods.

Topics: Animals; Anthraquinones; Bone and Bones; Bone Development; Fluoresceins; Fluorescent Dyes; Histocytochemistry; Rats; Rats, Sprague-Dawley; Tetracycline; Xylenes