Effect of phosphate treatment of Acid-etched implants on mineral apposition rates near implants in a dog model

Abstract

Purpose: This study evaluated the effects of phosphate coating of acid-etched titanium on the mineral apposition rate (MAR) and new bone-to-implant contact (BIC) in a canine model.

Materials and methods: Titanium implants (2.2 3 4 mm) with acid-etched surfaces that were electrolytically phosphated or not were placed in 48 mandibular sites in six foxhounds. Tetracycline and calcein dyes were administered 1 week after implant placement and 1 week before sacrifice. At 12 weeks after implant placement, the animals were sacrificed. MAR and BIC were evaluated using fluorescence microscopy. Light microscopic and histologic evaluations were performed on undecalcified sections.

Results: Microscopic evaluation showed the presence of healthy osteoblasts lining bone surfaces near implants. Similar BIC was observed in phosphated and nonphosphated titanium implant sites. MAR was significantly higher around the nonphosphated titanium implant surfaces than around the phosphated titanium samples. No significant differences were found between dogs or implant sites.

Conclusion: Acid-etched implants showed significantly higher MARs compared to acid-etched, phosphate-coated implants. Int J Maxillofac Implants 2010;25:278-286.

Fig 1

Photomicrograph of a section of bone showing tetracycline (red) and calcein green (green) uptake to illustrate how measurements for mineral apposition rate (MAR) were made. Thick white lines indicate the lines tracing the leading edges of the label. Thin white lines indicate the distances between the lines averaged by the Bioquant software to give MAR.

Fig 2

Photo showing 4 implants 12 weeks after placement. Two implants have bone growth over the coronal aspect (asterisk) and two implants are level with the alveolar ridge (arrows).

Fig 3

Photographs of fluorescent labeled bone. Red color=Tetracycline dye, Green color=Calcein. (a) Acid-etched only titanium (control). (b) Phosphated and acid-etched titanium (experimental). (c) Acid-etched only titanium (control). (d) Phosphated and acid-etched titanium (experimental). (e) Buccal dehiscence. (f) Bone covered over top of implant. a, b, e, f magnification ×2; c, d magnification ×10.

Fig 4

Mineral apposition rates for control and experimental implants. Significant differences were detected between the dogs. Lines represent standard deviation. (Control=Acid-etched titanium; Experimental= Phosphated and acid-etched titanium).

Figure 5

New bone-to-implant contact for control and experimental groups. No significant differences were detected between the phosphate and non-phosphated groups between dogs. Lines represent standard deviation. (Control=Acid-etched titanium; Experimental=Phosphated and acid-etched titanium).

Figure 6

Total, old, and new bone-to-implant contact for control and experimental implant groups. No significant differences were detected between the phosphate and non-phosphated groups between dogs. (Control=Acid-etched only titanium; Experimental=Phosphated and acid-etched titanium).