italiano espanol francais english
         
 
 

The qualitative tests for Overfibers are fundamental element in order to guarantee own customers reliability of the post Over Post and Hi-Rem Post in all the clinical requirements



Surface roughness

The surface roughness of the fiber posts is extremely important as this influences the adhesion strength of the post to the adhesive cements used to secure it to the tooth.

The rougher a post is, the greater the bond which the adhesives and composite resins can contract on its surface. Overfibers Over Post and Hi-Rem Post are available immediately with an extremely rough surface, capable of guaranteeing an extremely high level of adhesive strength.

In fact, they possess a mean level of roughness of 3.762 +/- 0.292 µm Ra and are significantly rougher than any other product analyzed by at least three times. As can be deduced from recent literature data*, the roughness of Overfibers posts corresponds to pre-treatments with 4% hydrofluoridric acid and sanding with the Rocatec system, and it is much greater than the treatment with 30% hydrogen peroxide.

As the surface area available for adhesion is directly proportional to the strength of adhesion itself, this characteristic considerably improves the bond of the post to the reconstruction material, such as fixing cement and reconstruction composite. Unlike other products present on the market, it is not necessary to perform any type of surface pre-treatment designed to increase roughness, thereby considerably reducing operating times.

Roughness test
The test was carried out using the PERTHOMETER M4P appliance (Perthen, Mahr) on five identical posts for each type of product. The data is expressed using the roughness parameter Ra. The difference in roughness between Overfibers posts and all the others is statistically significant.

Values are expressed in µm, the higher the roughness, the higher the Ra value

ANOVA - Analysis of Variance
Group
N
Mean
Std Dev
1
5
3.762
0.292
Overfibers Over Post, Hi-Rem Post
2
5
1.158
0.1339
Dentsply Illusion
3
5
0.49
0.1336
Ivoclar FRC Postec Plus
4
5
1.188
0.1252
3M ESPE RelyX
5
5
0.772
0.1303
Ultradent Unicore





**Microtensile bond strength of fiber post: effect of surface roughness  P. BALDISSARA, C. MONACO, L.F.  VALANDRO
University of Bologna, Bologna, Italy and Federal University of Santa Maria, Brazil

*Mazzitelli et al.: Surface roughness analysis of fiber post conditioning process. J Dent Res 2008;87:186-190

Surface Analysis

Overfibers Hi-Rem posts have been analyzed using an electronic microscope in order to evaluate the surface characteristics. Observations regarding the surface at various magnifications (100, 500 and 1000X) have been carried out, using a similar product which has been on the world market for years as a reference sample.

As can be deduced from the images (figs. 1, 2, 3, 4 ), the Hi-Rem Posts products present very rough surfaces which are full of indentations, clearly superior to the reference post (Fig. 5 ). The greater surface created by this roughness facilitates and increases the adhesion strength of the dental adhesive systems used to secure the post in the dental root, with considerable clinical advantage of duration and stability

Hi-Rem Post
 
Conventional post
 
Fig. 1: Hi-Rem Post surface; it is possible to note the high level of roughness of the surface. 100X Fig. 5: Surface
of a
conventional
post  the
surface is
visibly smoother
than Hi-Rem
Posts . 100X.
Fig. 2: Hi-Rem Post surface; another image at 100X which shows a surface which is considerably microretentive. 100X    
Fig. 3: Hi-Rem Post surface; on the post, the fibers and matrix resin present deep micro retentions. 500X    
Fig. 4: Hi-Rem Post surface; it is possible to note countless recesses and micro retentions for adhesive materials. 1000X    






Resistance to sterilization in autoclave

Hi-Rem Posts may be subjected to sterilization cycle in the latest generation of modern autoclaves (2008) in complete safety.

The test was carried out with a sterilization cycle in a heat-sealed bag at 135°C and 2 bar of pressure.

The sterilized Hi-Rem Posts were compared to a control group, determining the bending resistance (N) and deformation (mm) with the application of the load at 45° (bending to shear).

The statistical analysis demonstrated that the maximum load values on breakage and deformation on breakage are as similar in the control group as in the experimental group (sterilized): in the latter group, the resistance value is even greater than the checks, and that of the lower deformation. It is therefore possible to affirm that the product can be sterilized in an autoclave in complete safety with the procedure described should the clinical needs require it.


 

Resistance on breakage (N)

Deformation on breakage (mm)

Controls

Sterilized

Controls

Sterilized

Media

133.3

135.9

2.068

2.054

DS

14.39

9.32

0.3931

0.3885













Cytotoxicity

Although the fiber posts are inserted inside the root canals and normally remain isolated from the oral context, a portion of the post may sometimes remain exposed to the mucous in the mouth due to the loss of the temporary restoration or as a consequence of fractures or breakages of the tooth; in the latter case, the post may also come into contact with the periodontal tissues (bone and gum), in the case the root has fractured: a post with no cytotoxic power is therefore desirable in to prevent secondary complications for the patient.

The biocompatibility and cytotoxicity tests performed in the laboratory on human fibroblasts in accordance with the ISO 10993 directives, allowed any cytotoxic power to be excluded and therefore Hi-Rem Posts can be considered absolutely biocompatible.

* “A practical Guide to ISO 10993 - Part 5 : Cytotoxicity”







Resistance to fatigue

The resistance to fatigue test is one of the fundamental parameters in order to envisage the long-term clinical success of a dental reconstructive system.

In fact teeth support millions of cycles of mastication during their permanence in the oral cavity. A post must be capable of resisting a high number of load cycles without breaking at a strength level of 25-30% of its resistance to breakage. Hi-Rem Prosthetic Posts # 3 have shown that they can resist 10 million fatigue cycles at 50 N, APPLIED AT AN ANGLE OF 45°, repeated 8 times per second, without ever breaking, simulating a physiological operational period of 30 years.










Overfibers S.r.l. - Via Selice, 13 40027 Mordano(BO) Italy - VAT Number 01723440382
Phone +39.0542.52153 - Fax +39.0532.1920219 - Email: info@overfibers.com