Ultraviolet Functionalization Improved Bone Integration on Titanium Surfaces by Fluorescent Analysis in Rabbit Calvarium
This study evaluated the effect of ultraviolet functionalization (UV) on bone integration ability in rabbit model, using epifluorescence microscopy. Each of 12 rabbits (n = 6) received randomly four titanium domes prepared with or without ultraviolet for 48 hours (UVC, λ = 250 ± 20 nm; Philips, Tokyo, Japan): (1) turned surface (T), (2) turned surface with UV (T-UV), (3) sandblasted (120 μm aluminum oxide) and etched by 18% hydrochloric acid and 49% sulphuric acid at 60°C for 30 min (SLA) and (4) SLA surface with UV (SLA-UV). Fluorochrome bone labels were marked by oxytetracycline at 25 mg/kg on 13th days and 14th days and calcein at 5 mg/kg on 3th days and 4th days before euthanization. The study samples were sacrified at 2 weeks and 4 weeks. The undecalcified specimens were prepared. The newly formed total bone of cross-sectional area (TB, %), the mineralized trabecular bone of cross-sectional area (MB, %), and the new bone and dome contact (BDC, %) were measured and analyzed by fluorescence microscope and Image Pro Express 6.0. The data of MB and TB showed new bone regeneration was increased in all groups, but no signs of difference were found. However, the means BDC of UV treatment on turned surface at 4 weeks, the UV treated on SLA surface at 2 weeks and 4 weeks were statistically significantly higher than the control group (P < .05). Within the limitations of the study, it can be concluded that ultraviolet functionalization on the titanium surface could enhance the new bone tissues and titanium surface integration.
Titanium dome design. The dome was with an internal diameter of 6.0 mm, outer diameter of 7.0 mm, thickness of 0.5 mm, height of 3.0 mm, some self-tapping screws on the root of the domes, and 2 circular holes on the top (diameter 0.8 mm).
The experiment designs. T indicates turned surface; T-UV, turned surface with ultraviolet irradiation; SLA, turned surface with sandblasted and acid etched treatment; SLA-UV, sandblasted and acid etched surface with ultraviolet irradiation.
The surgical procedures. (a) The four circular grooves were prepared by the circle drill. (b) The four titanium domes were placed with self-tapping.
Figure 4. Light micrographs of fluorescent label, transverse cross-sectional views in the contralateral site after 2 weeks of healing (scale bar = 500 μm). (a) The turned surface group was partly filled little slender new trabeculae bone along the original cortical bone without connecting with the inner walls at the bottom. (b) Turned surface with ultraviolet irradiation group. Some bone tissue started to connect with the inner walls and climb up. (c) Turned surface with sandblasted and acid etched treatment group. The center of the new bone formed toward the skull surface was growing. (d) The sandblasted and acid etched surface with ultraviolet irradiation group demonstrated new bone directly deposition and an obvious increasing height. It was less bone tissue at the center area than close-up to the wall. Figure 5. Light micrographs of Fluorescent label, transverse cross-sectional views in the contralateral site after 4 weeks of healing (scale bar = 500 μm). (a) Turned surface (T) group, the newly bone tissue was continuation to deposit along the calvarial bone surface. (b) Turned surface with ultraviolet irradiation (T-UV) group. Compared with T group, the thin bone trabeculae being in contact with the inner titanium surface was nearly one-half of the total length of the dome for T-UV group and little bone tissue was formed at the center area of the dome. (c) In the sandblasted and acid etched surface group, total bone tissue is more than that in T-UV dome and the height of newly bone at the center area. (d) In the sandblasted and acid etched surface with ultraviolet irradiation group, the total inner length of the dome was occupied by the thin bone trabeculae. NB indicates new bone tissues; HB, host bone; CB, cortical bone.
Sandblasted and acid etched surface with ultraviolet irradiation (SLA-UV) group at 4 weeks. (a and b) Low-magnification image ×40 from the SLA-UV group. White asterisks indicates newly bone tissue that formed and grow along the inner surface of titanium group (scale bar = 500 μm). (c and d) The slim trabeculae bone were in contact with inner surface (original magnification ×100, scale bar = 500 μm). (e) White asterisks indicate newly formed bone tissues almost filled the whole dome at 4 weeks (original magnification ×40, scale bar = 500 μm). (f and g) Higher magnification of newly formed bone tissues at the top of the titanium dome (original magnification ×100, scale bar = 500 μm). NB indicates new bone tissues; HB, host bone; CB, cortical bone; MB, mineralized bone.
Ultraviolet (UV) light-induced new trabecular bone, mineralized bone, and bone–dome contact were evaluated by t test. The data of mean bone and dome contrast for turned surface at 4 weeks and sandblasted and acid etched (SLA) surface at 2 weeks and 4 weeks were statistically significant between UV light-treated and untreated control surfaces; *P < .05, respectively.
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