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Journal of Oral Science & Rehabilitation Volume 2 | Issue 4/2016 33 I m p l a n t s u r f a c e s a n d b l a s t e d w i t h t i t a n i u m d i o x i d e m i c r o p a r t i c l e s Introduction Per-Ingvar Brånemark, a Swedish professor, demonstrated that osseointegration of titanium implants is such that the bone remains in close contact with the implant surface without any intervention by the connective tissue, although the titanium dioxide (TiO2) layer interacts direct- ly with the bone tissue.1 The physical and chem- ical features of titanium, particularly its intrinsic properties, such as biocompatibility, low specif- ic weight, high strength–weight ratio, low mod- ulus of elasticity, and excellent corrosion resis- tance, are favorable for the manufacture of dentalimplants.2 Furthermore,titaniumsurfaces can be modified in an attempt to enhance their biological properties.3 Such modifications are achieved by adding a coat consisting of different types of bioactive substances, by removing por- tions ofthe externallayerwiththe use ofblasting materials of different particle sizes, or by apply- ing chemical treatments and/or physical ones, such as laser.4 Among these, blasting and acid etching have been the most widely used. In ad- dition, their combination has shown improved biological activity of titanium surfaces in terms of implant osseointegration relative to smooth (machined) surfaces.5 The modification of the implant surface can thus have benefits regardingthe response ofthe surroundingbonetissue,acceleratingthehealing processand/orimprovingthequalityofthenewly formed bone.5–7 Studies have shown that osseo- integrationisrelatedtomicrogeometricfeatures, such as the degree of surface roughness, and to factors such as the physical and chemical prop- erties of surfaces.7, 8 Rough surfaces were found to stimulate osteoblastic gene expression andto enhance bone formation and bone implant fixa- tion.9, 10 While an associated inflammatory re- sponse was reported,11 the overall success rate was satisfactory, with the majority of implants yielding good osseointegration and stability one year after surgery.12 Dental implant manufacturers have de- veloped and marketed implants with several types of chemical and physical surface treat- ments.13 However, there is still no consensus on whattheoptimalconditionsforperiimplantbone growth are. It is known that bone response can be influenced by implant surface topography at the micrometer level, and it has been hypothe- sized that a nanometric surface can also have an effect.14 Notwithstanding, the mechanisms be- hind an optimal bone response to a given type of surface still remain largely unknown. Surfaces known as SLA (sandblasted, large- grit, acid-etched) are produced by blasting with microparticlesofsomematerialsfollowedbyacid etching. Alumina is one of the most widely used materials, but some authors have highlighted some features of alumina blasting that could compromise osseointegration (e.g., particle de- tachmentduringthehealingprocessandabsorp- tion by the surrounding tissues).15 The presence of alumina residues on implant surfaces due to the manufacturing process has been regarded as a potentialrisk, compromising long-term osseo- integration.16, 17 Alternatively, TiO2 is used as a blasting material and has shown interesting re- sults in experimental studies. Particularly, TiO2-blastedimplantswereassociatedinhumans with a significant enhancement of bone-to- implant contact (BIC) when compared with ma- chined surfaces.18–20 Under unfavorable clinical conditions,suchasinthepresenceofpoor-quality bone,fastandpredictableosseointegrationwould bebeneficial,allowingprostheticrehabilitation.In the case ofinsufficient bone quantityoranatomi- callimitations, orinthe presence oflocaland sys- temic conditions that could compromise long- term osseointegration, implants with a rough surfaceshowbetterboneappositionandBICthan dothosewithsmoothsurfaces.21,22 Therefore,the aim of the present in vivo study was to evaluate thebehaviorofsurfacesshortlyafterimplantation by measuring removal torque and analyzing his- tological parameters. Materials and methods Twenty-four cylindrical self-tapping implants with internal hexagon packaged and ready for salewereusedforinvivotesting.Twelveimplants with a machined surface (Fig.1)were used inthe control group (C group). Twelve implants with surfaces sandblasted with 50–150 μm TiO2 microparticlesata5atmpressurefor1min,ultra- sonicallycleanedwithanalkalinesolution,rinsed in distilled water and then conditioned with maleic acid (Fig. 2) were used in the test group (T group). The implants (Implacil De Bortoli, São Paulo, Brazil) were 4 mm in diameter and 8 mm in length. Six mature New Zealand white rabbits were used in this study. This study was approved by the Ethics Committee (#004-09-2015) of the Volume 2 | Issue 4/201633