Projects / Programmes
Treatment effectiveness of orthodontic fixed appliances in correlation with surface changes of their metal parts
| Code |
Science |
Field |
Subfield |
| 3.02.00 |
Medical sciences |
Stomatology |
|
| Code |
Science |
Field |
| B000 |
Biomedical sciences |
|
| Code |
Science |
Field |
| 3.02 |
Medical and Health Sciences |
Clinical medicine |
orthodontic fixed appliances, treatment effectiveness, surface state, dental material
Researchers (11)
Organisations (2)
Abstract
Orthodontic fixed appliances enable tooth movements in three dimensions (3D) between the physiological limits of surrounding tissues. The effectiveness of treatment depends upon the responsiveness of surrounding tissues and upon the characteristics of the fixed appliance itself. The effect of mechanical characteristics of fixed appliances will be evaluated in order to assess the treatment effectiveness in-vivo.
Fixed appliances are composed of brackets, archwires and ligatures. The bracket with wings enables to tight the archwire using either an elastomeric or metal ligature in the brackets’ slot. The bracket is specifically designed for each tooth in the dental arch and the information about tooth position is built into its slot. During treatment different regions of the brackets’ slot and arch wire are in contact, leading to surface changes in the contact region.
During several years of orthodontics treatment the metal parts of fixed appliances are subjects to mechanical stress and corrosion. Changes due to wear and the concomitant process of corrosion worsen their characteristics, including biocompatibility, decreasing the effectiveness of moving teeth in their correct position.
Aim
The aim of the present study is to assess the treatment effectiveness of fixed appliances in correlation with surface changes of their metal parts (brackets and archwires).
The surface changes of the metal parts of fixed appliances will be studied by the use of different non-destructive and destructive methods in correlation with the effectiveness of tooth positioning.
Pre-, during and post-treatment study casts of the dental arches of forty randomly selected orthodontic patients will be obtained to assess changes in tooth position. After 6 months of treatment half of the brackets in each subjects’ mouth will be debonded for in-vitro analysis and replaced with new brackets and treatment will be continued.
Three-dimensional images (3D models) of pre-, during and post-treatment plaster casts will be obtained using a 3D laser scanning system and changes of each tooth position in 3D will be assessed using superimposition techniques.
The surface of the metal parts of fixed appliances will be studied before, during and after treatment using an optical, electronic and if needed a confocal microscope or a X-ray tomograph for metals.
An in-vitro study will be conducted simultaneously to assess the composition, surface changes and physical changes of orthodontic brackets and archwires due to different chemical and mechanical wear. Some surface changes like excessive calcination, oxidation or the loss of passive film will be studied as well. Using a tribocorrosion system the simultaneous effect of mechanical wear of the metal parts and corrosion will be tested. The mechanical and corrosion contributions to the wear process in the artificial saliva simulating the conditions in the mouth will be assessed.
At the end of the research comparisons of the in-vitro and in-vivo results will be performed.
Mechanical wear and damage of the metal parts could be correlated with post-treatment tooth position, and could lead to a decreased accuracy in the final placement of teeth in the dental arches. This could lead to a less efficient and economically more complex orthodontic treatment. In the present research, factors influencing mostly the mechanical wear and damages of the surface of metal parts will be evaluated and new knowledge for further research in terms of improvement of the metal parts’ surface characteristics will be acquired. This will lead to a higher efficiency of orthodontic treatment.
Significance for science
The interdisciplinary project, that established a close link-up between the high technology of advanced materials and dental and jaw orthopaedics, lead to original results on the influence of clinical ageing of orthodontic appliances at specific intraoral conditions on their surface and mechanical characteristics. The results evidenced that the intraoral ageing processes are mainly a synergy of various mechanical and electrochemical events (corrosive cracking, corrosive fatigue, tribocorrosive processes) that are the most evident for alloy materialy that form stable passive films (titanium alloys, stainless steel). We also found, that sruface changes influence the biomechanics of tooth movement, mainly affecting friction force, but do not have a major impact on the final tooth position.
Significance for the country
The research project stimulated the interdisciplinary collaboration (civil engineering , chemistry, physics, medicine and dentistry) and it implemented developmental and innovation technology between research groups and companies. In orthodontics and dentofacial orthopaedics an important condition for achieving quality products, of which the leading companies are aware, is the importance of choosing good quality materials in different wires and brackets for treating different malocclusions. One basic criterion is the assurance for sustainable durability of materials at the chosen environment (combination of mechanical, physical and chemical wear in intraoral environment). Due to surface changes of metallic materials unexpected treatment difficulties may arise which may prolong the necessary time for treatment. Because of new technologies and the rising demands for higher standards in orthodontic treatment in the shortest possible time the proposed research in this interdisciplinary field is highly in order. Shorter treatment time and higher quality in treatment of malocclusions is less costly and available to a larger part of the population. Even more important is the fact that prolonged time of treatment may lead to soft and hard tissue damage. The results of the research project improved the knowledge on intraoral ageing mechanisms and their influence on orthodontics treatment with fixed appliances.
Most important scientific results
Annual report
2013,
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2013,
2014,
2015,
final report
