Scientifica implantology

Open Journal of Stomatology, 2016,6: 12-21, doi: 10.4236/ojst.2016.61002

This finite element analysis assessed the different load distribution of Toronto Bridge prostheses (with cantilever) of the all-on-four vs six-implant configurations. The results showed that the fewer the number of implants, the greater the stress on the bone. The authors recommended minimising the length of the cantilever as much as possible.

J Oral Science Rehabilitation. 2016 Sep;2(3):26?33.

This study based on fatigue tests compared different types of abutments for temporary and definitive prosthesis, demonstrating that the definitive titanium abutments can resist forces 5 times higher than the castable abutments. The study also demonstrated that, unlike the temporary titanium abutments, the castable abutments, if used being casted as they are meant for, cannot withstand masticatory forces, as titanium abutments do.

Med Oral Patol Oral Cir Bucal. 2011 Sep 1;16 (6):e852-6

The aim of this study was to evaluate the biomechanics of the implant-post system in the case of a traditional and switching platform configuration by means of a finite element analysis. With the proper precautions, it can be affirmed that this technology allows bringing the biomechanical events back to a digital model, analysing the distribution of the stress and evaluating any biological repercussions. The higher the definition (number of nodes and elements), the closer to reality the analysis.
In this case, a 3D finite element analysis was conducted after constructing a mesh with 60,000 elements and 100,000 nodes. To make the analysis conditions as real as possible, special attention was placed on the bone definition. This involved drawing both the cortical and medullary component with the different biophysical characteristics (Young module).
Three different implant-post configurations were evaluated:
1. Implant with a diameter of 3.8 mm and corresponding post (Standard control model)
2. Implant with a diameter of 5.5 mm and corresponding post (increased control model)
3. Implant with a diameter of 5.5 mm and 3.8 mm post (experimental model with switching platform configuration).
A Global implant manufactured by Sweden & Martina was used.
In accordance with the literature and the ISO standards which standardise the experimentation conditions, vertical (axial) loads of 130N and horizontal loads of 90N were applied on the crown portion of the post. With these load conditions, the Von Mises stress index was evaluated and the minimum and maximum values were recorded for each implant-post configuration.
At the end of the experimentation, the Von Mises stress levels recorded on the standard configuration induced by the load varied from 150 MPa to 58 Pa (at an implant level) and from 150 Mpa to 52 MPa (at an abutment level); in the configuration of the increased model, the stress levels varied from 45 MPa to 55 Pa (implant) and from 70 MPa to 55 MPa (abutment); in the switching platform configuration, the stress levels measured varied from 190 MPa to 64 Pa (implant) and from 85 MPa to 42 MPa (post). The maximum stress levels transmitted by the implant-post system to the cortical and trabecular bone were respectively 67 Pa and 52 MPa (standard configuration); 54 Pa and 27 MPa (increased configuration) and 64 Pa and 42 MPa (switching platform). An evaluation of the stress levels on the body of the fixture
allowed highlighting a substantial reduction in stress in the threading region, correlated to a diameter difference between the implant and post in the switching platform configuration. In conclusion, it can be affirmed that the switching platform configuration not only leads to a relative reduction in the stress levels compared to standard configurations (both standard and increased), but also to a significant movement in the stress area from the bone to the implant platform, thus potentially generating less overloading of the bone crest.

This mechanical finite element study evaluated the different distribution of the stress levels between implants with a small and large diameter restored with traditional protocol, comparing them with implants restored with reduced abutments according to the switching platform concept. The results demonstrated that the switching platform configuration not only leads to a relative reduction in the stress levels compared to standard narrow and large configurations, but also to a significant movement of the stress area, potentially resulting in less overloading of the bone crest.

Italian Dental Journal, 2011

IMMEDIATE LOADING OF AN EDENTULOUS MANDIBULAR CREST WITH SIMPLE TECHNIQUE

This interesting clinical case is an excellent example of the use of SIMPLE posts in immediate load in a mandibular arch, illustrating its ease of use and practicality.

Rassegna Odontotecnica, 9: 33-48, 2000

Journal of Prosthodontics, 19(8):614-619, 2010

Resistance to wear of four matrices with ball attachments for implant overdentures: a fatigue study. This study was conducted by the Department of Dental Prosthesis of the University of Florence and examined the wear resistance and retention force of four different types of ball attachments for implantretained overdentures with the use of an in-vitro fatigue test simulating 5500 cycles of insertion and removal. Dimensional changes of the ball attachments were investigated with a profi lometer. The
matrices used were a Tefl on matrix (with metal housing), a titanium matrix, a gold alloy matrix and an o-ring for medium retention.
The Tefl on matrices showed an increase of 27% in retention at 5500 cycles, remaining relatively stable up to 5500 cycles, while the titanium matrices and o-ring matrices exhibited progressive loss of retention up to 68% and 75% at 5500 cycles. The dimensional analysis by profi lometer revealed signifi cant wear on the ball attachment only for the titanium matrices.
Therefore, it can be stated that the gold alloy and Tefl on attachments showed the highest retention values without retention loss after 3 years of simulated function (equal to approximately 5500 cycles).

An interesting cyclic fatigue study that showed how the gold alloy and Tefl on matrices for ball attachments maintained a higher retentive capacity than the titanium matrices over time. The study also demonstrated greater wear of the ball heads of the attachments when used with titanium matrices.

Minerva Stomatologica, 58(1-2):9-23, 2009

This study analyses the load effects of the masticatory cycles on a Toronto prosthesis on Global implants and suggests that the position, angle and size of the implants are determining factors for the long-term success of the prosthesis in relation to the anatomy of the receiving bone.

XXXVII Convegno Nazionale, AIAS Associazione Italiana per l?Analisi delle Sollecitazioni, 10-13 settembre 2008, Università di Roma la Sapienza, Abstract collection

A complete prosthetic system (jaw-fi xture-prosthesis) was evaluated with the FEM to parameterise the effectiveness of three different Toronto structures on Global implants. The result shows how the choice of different implant sizes, the distribution of the fi xture spaces and sizes of the superstructure have a direct impact on the effectiveness of the distribution of prosthetic loads and mechanical stress.

Minerva Stomatologica, 57(4):167-79, 2008

This extensive clinical study compared the result of the screwed prosthesis and cement-retained prosthesis in numerous case reports of implant lines available on the market. The type of prosthetic solution did not infl uence in a statistically signifi cant manner the osseointegration of implants at 34 months, which was good in both cases.

Implant Dentistry, 2014, 23(6): 665-671

A mechanical study on cyclic fatigue stress in accordance with the UNI EN ISO 14801: 2008 was carried out on 3.8 x 13 mm Premium implants, simulating worst-case conditions. The implants showed excellent capacities of resistance to the loads applied, and are suitable for rehabilitations in both frontal and molar sectors.