Phosphoric Acid Increases the Porosity and Extends the Contact Area of Dental Osseo integrated Implants

The surface treatments are performed in dental implants in order to increase the chemical and mechanical connection between the implant and bone, favoring the stability of implant-supported prostheses. The aim of this study was to characterize dental implant surfaces treated with 37% phosphoric acid. Implant surfaces were evaluated divided into groups of fifty samples being distributed in: porcelain samples without treatment; metal samples without treatment; porcelain samples with treatment with 37% phosphoric acid for 30 seconds; metal samples treatment with phosphoric acid at 37% for 30 seconds; porcelain samples with treatment with 37% phosphoric acid for 60 seconds; metal samples with treatment with 37% phosphoric acid for 60 seconds. The samples were characterized by Scanning Electron Microscopy. After the phosphoric acid treatment porosity changes were observed and expanding the contact area. The results show benefits of using phosphoric acid, as a surface with increased roughness; this is desired to occur matrix deposition and growth of bone tissue and facilitates the fixation of implant-supported prostheses.


INTRODUCTION
A dental implant is a treatment to replace missing teeth has become an integral treatment modality in Odontology. Dental implants have several advantages in relation to conventional fixed partial denture. Among them it is possible to highlight: high success rate (over 97% for 10 years); reducing the risk of cavities and endodontic problems of adjacent teeth; best bone maintenance in edentulous site and decreased sensitivity of the adjacent teeth. It is a structure located in the tissues under the oral mucosa and / or the periosteum and / or within or through the bone to provide support and retention for a dental prosthesis (Gupta;Weber, 2017). For biocompatibility and implant success determining factors are considered: the geometry, surface condition, the general state of health of the host, the surgical technique and control of the mechanical load after installation of the implant. Several studies have sought to compare different surface treatment methods and their influence on the mechanisms involved in the acceptance or rejection of the implant, as well as the cellular response and intensity of inflammation (Brandão, 2010;Fugazzoto;Vlassis, 2007;Kang, 2009). The increased contact area between bone and implant can be obtained by changing the topography or by increasing the surface roughness of the implant (Anselme et al., 2000). The relationship between the success of the implant and the cement used for fixation of the prosthesis is still not fully understood. Despite the stage of cementing is one of the stages of the clinical protocol indirect restorative, which was modified in the transition from the use of conventional systems for so-called aesthetic-adhesive systems or metal-free, in the literature, there are few works related to mechanical and each adhesive system, as well as the properties and limitations of adhesives and cementing systems that can lead to early failure of implant-supported prostheses (Garofolo, 2005 solution, and maintained for a given time interval , with small ridges or retention surfaces (Nagem Filho, 2007). The aim of the study was to characterize surfaces of dental implants of different materials, treated with 37% phosphoric acid by volume.

II. MATERIALS AND METHODS
For the treatment effect was considered the inner surface of the prosthetic implant and the implant external metal. The concentration of phosphoric acid used was 37% and treatments were performed two times, 30 seconds and 60 seconds. A control was also performed without the treatment with phosphoric acid. Three hundred samples were prepared, divided into six groups, with fifty units in each sample. Where: Group 1: porcelain samples without treatment with phosphoric acid at 37%; Group 2 metal samples without treatment with phosphoric acid at 37%; Group 3: porcelain samples treatment with phosphoric acid at 37% for 30 seconds; Group 4 metal samples treatment with phosphoric acid at 37% for 30 seconds. Group 5: porcelain samples with treatment with 37% phosphoric acid for 60 seconds; Group 6 metal samples with treatment with 37% phosphoric acid for 60 seconds. The porcelain samples were prepared mimicking the buccal surface of the upper incisor teeth, having its inner surface received etching with phosphoric acid at 37% for 60 seconds, leaving an area not in contact with the acid to indicate the difference in opacity between the treated area and the untreated area.
The metal inner surface received etching with 37% phosphoric acid for 60 seconds, leaving an area not in contact with acid, to indicate the difference in opacity of treated area and untreated area. Using scanning electron microscopy the surface was mapped and the data registered in photomicrographs.

III. RESULTS
After treatment of the samples with phosphoric acid application at 37% were observed on the surface changes as a function of time. The exposure to phosphoric acid made more opaque surface. Figure 1 shows the differences between the samples without attack on the inner surface of the prosthetic implant and the external surface of the implant, in the presence or absence of phosphoric acid treatment. What is observed is that surfaces of both porcelain and metal before the treatment with 37% phosphoric acid are smoother and therefore more homogeneous (A), where these surfaces are exposed to the treatment with phosphoric acid 37% for 30 seconds characteristics of surfaces are becoming opaque and therefore less bright (B), however the images in (C) after the surfaces were exposed to treatment with phosphoric acid at 37%, for 60 seconds, the surfaces have much more opaque and less bright, suggesting that the higher the greater exposure to acid changes in their structure. It is observed that after 60 seconds of treatment with phosphoric acid the surfaces of both porcelain and metal feature are changed, as indicated by arrows in Figure 1. ://dx.doi.org/10.22161/ijaers.5.3.30  ISSN: 2349-6495(P) | 2456-1908(O) www.ijaers.com Page | 232 ://dx.doi.org/10.22161/ijaers.5.3.30  ISSN: 2349-6495(P) | 2456-1908(O)

www.ijaers.com Page | 233
In Figure 2 is the analysis of the porcelain surfaces treated and not treated by phosphoric acid at 37% in the scanning electron microscope, there is an area treated with strong porosity.

Fig.2: Photomicrograph of porcelain surfaces; in A the untreated, in B treated with phosphoric acid and after 30 seconds and in C treated with phosphoric acid after 60 seconds (SEM image at 1000x magnification).
Figure 3 refers to the photomicrographs of untreated and treated metal surfaces with phosphoric acid. It is noted that the treatment in metal was effective for increasing the contact area with cement, which may improve the attachment the prosthesis. ://dx.doi.org/10.22161/ijaers.5.3.30  ISSN: 2349-6495(P) | 2456-1908(O)

IV. DISCUSSION
The need for development of dental treatments to supply the missing teeth stimulated the search for studies of the production of prosthetics they need to have a restraint system that provides retention and stability of the prosthetic element, which allows the patient to use with functionality and aesthetics. The treatment of the internal surfaces of the prosthetic implant can directly influence the physical and mechanical properties of the joint prosthesis / implant, culminating in a reduced line of cementation and better fixation of prosthetic implants for dental use.
According to the data obtained, the implant surfaces treated with phosphoric acid undergo structural changes which can influence the success of the dental implant. Scanning electron microscopy analysis revealed that the surfaces of both metal and porcelain implants have undergone considerable surface changes with increased porosity. The breakage caused by phosphoric acid on the surface suggests an increase in porosity, expansion of the contact area of the cement fixer and imbrication of the favored cement, which may increase the anchorage of the prosthesis over the implant. The different surface pretreatment (chemical, mechanical, or both) to the surfaces that make up the cementing line are proposed in the literature (Lohbauer et al, 2008; On the other hand, another study reported clinical complications associated with cemented prostheses on dental implants use, requiring rigorous clinical controls, to check for changes in the peri-implant tissue. The main cause of the observed problems is excess cement and suggest that it is necessary rigorous clinical controls, so that they can examine the changes in the peri-implant tissue in their early and act quickly to avoid a major complication (Pauletto et al, 1999).

V. CONCLUSION
The results obtained allow us to conclude that there is a beneficial action of phosphoric acid when applied to implant surfaces, causing porosity changes and expansion of the contact area of the surface, which may have important clinical implications.