The integration of orthodontic miniscrews under mechanical loading: a pre-clinical study in rabbit.

INTRODUCTION: Orthodontic miniscrews are an increasingly popular choice to achieve absolute anchorage. The temporary use of miniscrews and their recent introduction have limited the debate over the biological aspect of the materials to that of the surface that permeates the field of dental implants. The aim of the present study was to investigate the integration of grade 5 titanium mini-implants with machined or sand blasted acid etched surface (SAE) under mechanical load in a rabbit tibia model of implant integration. METHODS: A total of 64 miniscrews (Ti6Al4V) of 1.5 mm diameter and 6.5 mm length were inserted in the proximal medial surface of each tibia in eight male rabbits aged 6 months. Each tibia received four miniscrews. A 100 g nickel-titanium coil spring (Neosentalloy) was applied between two miniscrews along the main axis while two miniscrews were left unloaded. The removal torque was measured for loaded and unloaded miniscrews after 12 weeks. Two miniscrews were harvested for histology. RESULTS: Removal torque was significantly higher for SAE mini-implants than for machined screws, under both loading conditions. Although no difference in bone to implant contact was observed among the groups, cortical area significantly decreased with both surfaces under loading. CONCLUSIONS: Our data indicate that SAE miniscrews have higher bone retention than MA miniscrews, although the effects of mechanical loading of these devices on cortical bone require further investigations.

Contact damage to root surfaces of premolars touching miniscrews during orthodontic treatment.

INTRODUCTION: Our aim in this clinical study was to examine premolar root surfaces after intentional contact with miniscrews. METHODS: Ten patients (5 male, 5 female; mean age, 15.8 years; range, 13.5-23.2 years) with 2 maxillary first premolars to be extracted as part of their orthodontic treatment participated in the study. Two miniscrews were placed in each patient, and the first premolar roots were tipped into contact with the miniscrews by using tipping springs with a standardized force. Half of the experimental teeth were kept in contact with the screws for 4 weeks (mild resorption) and the other half for 8 weeks (severe resorption). In 5 patients, the screws were removed, and, in the remaining 5, the springs were removed to allow the roots to move back. The roots were allowed to recover for 4 or 8 weeks before extraction. Two premolars with accidental direct contact were used as controls. All teeth were prepared, coated, and examined with scanning electron microscopy. RESULTS: In the control group, the periodontal ligament was removed and the dentin surface denuded. The experimental groups showed signs of resorption with structural surface irregularities. However, no apparent denuded dentin surfaces were seen. Although some resorption lacunae were still discernible at 8 weeks, the collagen fibers fully covered the affected areas. The immature fiber organization in the deepest crater represented the ongoing process of fiber reorganization, compared with the fully matured surface areas surrounding the crater. CONCLUSIONS: The results indicate that root surfaces that touch miniscrews show swift repair and almost complete healing within a few weeks after removal of the screw or the orthodontic force. These findings are based on 10 patients only; verification in a larger study sample is needed.

MGBM system: new protocol for Class II non extraction treatment without cooperation.

This article describes a method to treat Class II malocclusions with no patient cooperation. The technique involves converting the Class II molar relationship to a Class I in the initial phase of treatment by moving the maxillary molars distally with superelastic coils and wire. Anchorage is provided by a transpalatal bar attached to the first premolars and connected to 2 palatal miniscrews. Once the molars are positioned correctly, the palatal miniscrews are removed and miniscrews are inserted bilaterally in the buccal bone between the first molar and the second premolar. These miniscrews serve as the anchorage for the retraction of the premolars, canines and incisors.

European community legislation concerning schools of specialisation in orthodontics: the inexplicable inertia of Italy--contradictions and open issues.

Orthodontics was the first discipline to be acknowledged as such within the field of dentistry, initially in the USA and subsequently in Europe. The structural changes that led to the birth of the European Union (EU) laid the foundations for the free circulation of professions and services. Nevertheless a deep discrepancy in the quality of training of practitioners from different countries became apparent. It was necessary to address this issue and regulate the training process in order to guarantee a degree of uniformity. Up to this time only the duration of the School of Specialisation in Orthodontics has been set at a minimum of three years. While moving towards an increasing degree of integration of the various EU countries, it becomes paramount to be able to establish a School of Specialisation in Orthodontics with high academic standards based on the Erasmus Programme and above all to be able to award a specialisation degree which is acknowledged first of all in the country where it is issued and also on a wider European level. Freedom of circulation of intellectual activities requires the formal acknowledgement of a qualification, namely the Specialisation in Orthodontics. Also to that end, EFOSA (European Federation of Specialists in Orthodontics) was founded. Furthermore the European Community has, in the meantime, ruled that medical trainees should be remunerated for their work. Dentistry and its specialisations should not follow the model of Medicine given that the two are completely distinct, but many believe that the duration of the School of Specialisation in Orthodontics has to be set as the same as the medical specialisations.

Spider Screw: skeletal anchorage system.

The stability of the anchorage unit plays a very important role in orthodontic control. Controlled orthodontic movements such as retraction and/or protraction of teeth and intrusion of overerupted teeth are very difficult to achieve without patient cooperation and without causing undesirable reciprocal movement in the anchorage unit. The article describes characteristics, surgical procedure, and clinical use of the Spider Screw as an ideal non-dental and non-cooperation based anchorage system. The Spider Screws are self-tapping, titanium mini-screws with immediate loading capability. Their utilization involves a simple biomechanical principle combined with the utilization of minimum orthodontic mechanotherapy. Ideal orthodontic forces (in the range from 50 to 250 gr) can be applied to achieve the desired orthodontic movements. Complete osteointegration is neither expected nor desired with this anchorage system. The Spider Screw anchorage system can be used to support a variety of orthodontic movements specifically in clinical situations involving incomplete dental arches and limited cooperation as in many adult orthodontic cases. The ease of surgical placement combined with the reduced dimension of the Spider Screw diameter equally permits its use in clinical situations where anchorage recovery is necessary during treatment of complete dentitions in classical orthodontic therapy.