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Aim: Aim of the study was to find effective instrumental methodologies and procedures for scaling and deplaquing without compromising the structure of metal-free, monolithic lithium disilicate and layered zirconia prosthetics., Methods: Of 14 decontaminated, extracted teeth in good anatomical condition, 7 veneers lithium disilicate monolithic and 7 layered zirconia crowns were prepared for testing and divided into 6 treatment groups. Each group was composed of a veneer and a crown. The division of the groups was carried out according to the type of treatment performed- instrumental carbon fiber and steel tips, prophylaxis paste with high and low RDA (Relative dentin abrasion), bicarbonate powder. Samples were examined and observed through a scanning electron microscope (SEM). Afterwards a detailed comparison of the images of treated and untreated samples was performed. The images were at the same magnification, thus showing the differences in the treated samples., Results: The monolithic lithium disilicate presents minor damage to the surface but no excessive changes to the structure in general post treatment. The layered zirconia resulted in notable damage with evident abrasions on the layered ceramic structure after the use of ultrasound with a steel tip and air flow with bicarbonate. Carbon fibre tips and prophylaxis paste containing perlite and low RDA did not create notable changes to the properties of the materials in question., Conclusion: The results of the disilicate monolithic appear to show it to be a much more resistant material compared to layered zirconia in ceramic. Its resistance is demonstrated by the lack of notable damage in all the treatment groups.

Objectives: The Author studied the variability of the vestibular surfaces of tooth usually involved in orthodontic treatment., Materials and Methods: 200 model casts of Italian subject with complete permanent dentition have been analyzed studying the clinical crown dimension and the angulations of tangents drawn at 3 and 4 mm., Results: The authors found differences in the vestibular surfaces curvature in the last teeth of each series, more accemptuated in the lower than in the upper arch., Conclusion: The conclusions of this study are related to the use of orthodontic straight wire appliances. The use of standard values with a complete torque, independently from the individuals, is based on the hypothesis of equal positioning on the tooth surface and related to the teeth axis. A variation in the torque of the upper central incisor for different kinds of straight wire appliance related to extreme variation of vestibular curvature is hypothesised.

Latex-free products have been introduced in orthodontics following a growth in the number of latex allergy cases reported. The aim of this study is to compare the efficiency between latex-free and latex elastics which are normally used in clinics. In this study, 80 latex-free and 80 latex elastics were divided into 4 groups of 20 elastics. Each group was exposed to a variable number of opening/closing cycles (100, 1200, 2400 or 4800), using a specially adapted machine which simulated the stretching of these elastomeric products during the dynamics of the mouth. The machine extended the elastics' inner diameter from 3 to 5 times its original dimension (the extension being comparable to that experienced during the opening/closing movements of the mouth). Following this, the elastics underwent a dynamic tensile test using the Instron 4301 machine to evaluate possible force loss and deformation. The different test results were analyzed using the Student t-test and ANOVA test of Tuckey. The test results showed differences between the two types of elastics particularly in the inner diameter behaviour: the increase in the inner diameter of the non-latex elastics' was pronounced. The forces applied by both types of elastics were similar until 2400 opening/closing cycles were reached. Thereafter, the nonlatex elastics lost a larger force (p < .01). The test results suggest that latex-free elastics must be replaced more frequently than conventional latex elastics.

Aim: The purpose of the study was to assess the effect of water and saliva contamination on the shear bond strength and site of bond failure of two different orthodontic adhesives (Transbond XT and cyanoacrylate Smartbond LC)., Materials and Methods: 120 bovine permanent mandibular incisors were randomly divided into 6 groups, and each group consisted of 20 specimens. Each adhesive was tested under three different enamel surface conditions: 1) dry, 2) water contamination, 3) saliva contamination. 120 stainless steel brackets (0.018-inch slot DB, Leone) were bonded in each test group with the respective adhesive. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in a shear mode on an Instron Universal Testing Machine. Shear bond strength and site of bond failure were evaluated. Kruskal-Wallis and Fisher's exact tests were applied to determine significant differences in terms of bond strength among the 6 groups. The chi-square test was used to determine significant differences in the Adhesive Remnant Index (ARI) scores., Results: Transbond XT showed the highest bond strength values when it was applied onto dry enamel (P < 0.0002). No significant differences were reported when Transbond was used either on water- or saliva- contaminated enamel (P = 0.5), however the bond strength values were significantly low. For Smartbond LC no significant differences were found between dry and moist with water conditions (P = 0.3). Significantly higher bond strength values were reported when Smartbond LC was used on saliva contaminated enamel (P = 0.002). Significant differences in debond locations were found among the different groups., Conclusions: The use of a cyanoacrylate adhesive is indicated under moist conditions (particularly saliva), and when a short setting time is required. This can be considered advantageous in clinical orthodontic bonding compared to conventional composites.

Orthodontically induced root resorption is the most frequent unwanted side effect of orthodontic tooth movement that is unavoidable. This is due to the fact that both bone remodelling and root resorption are based upon a sterile inflammatory process, initiated by force application. In addition to individual factors that have a bearing on the amount of resorption, the type and magnitude of orthodontic forces play a major role. In animal and human experiments it could be shown that continuous forces, as produced by materials with pseudo- elastic characteristics, seem to produce more resorptions than discontinuous forces. Recent research shows that the magnitude of the orthodontic force up to 200cN is probably not decisive for root resorption.

Background: During the last 5 years, anchorage control with self-tapping miniscrews has become an important part of the clinical management of orthodontic patients. Yet, no studies have been performed for measuring mechanical properties of the currently available systems., Objectives: The purpose of this study is the evaluation of mechanical properties of three commercially available self-tapping screw systems used in orthodontic treatment., Materials: three systems with a 1.5 mm diameter and 11 mm length screw (Leone, Firenze, Italy; M.A.S. Micerium, Avegno, Italy; Dentos, Korea) were examined. The results compared the resistance to bending, torque, pullout of each screw and the insertion moments needed to screw down each sample., Conclusions: All three miniscrews have mechanical properties that contribute to their safe use as skeletal anchorage in orthodontics. Although stainless steel has demonstrated to be more resistant to failure than titanium, its overall performance as material for miniscrews could be inferior to titanium. In order to facilitate the insertion, the asymmetric profile of the thread should be preferred to the symmetric cut. The ratio between the diameter of the drill and the diameter of the corresponding miniscrew is pivotal for the successful implantation and resistance of the miniscrews. Looking at the mechanical properties evaluated in this study, a cylindric shape of the screw is better than a conic one. The conic shape could be preferred in case the site of insertion is iterradicular and therefore limited to 2.5-3.5 millimetres.

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.

Aims: anchorage control with self-tapping screws has become an important part of the clinical management of the orthodontic patients. Mechanical resistance and sites of insertion of miniscrews as orthodontic anchorage are critical to ensure successful outcomes. Aim of this clinical study was threefold: 1) to measure the mechanical resistance of the M.A.S., 2) to evaluate if the alveolar areas usually selected for mini-screws placement are adequate, 3) to illustrate the most frequent clinical application on the maxillary alveolar bone., Methods: two methods were chosen to test these screws mechanically, representing two potential modes of failure during insertion or removal: torsional strenght and bending strenght. Three-dimension images of fifty maxillas have been retrieved from a group of 200 patients, age range between 20 and 40 years with a new type of tomogram called Newtom System. For each area mesio-distal and labio-lingual measurements from four horizontal cuts made at 2-5-8-11 mm below the bone-crest have been evaluated., Results: the mean value of resistance to breakage in torsion is of 48.7 N.cm (around 5 Kg) for the miniscrew of 1.5 diameter, while the mean value of resistance to breakage in torsion is of 23.4 N.cm (around 2 Kg) for the miniscrew of 1.3 diameter.. The mean value of resistance to breakage in flexion is of 120.4 N (around 12 Kg) for the miniscrew of 1.5 diameter, while the mean value of resistance to the flexion is of 63.7 N (around 6 Kg) for the miniscrew of 1.3 diameter. On the maxillary alveolar bone the highest amount of bone was in mesio-distal dimension between 6 and 5 on the palatal side (minimum 1.9 mm at -11 mm cut; maximum 5.5 mm at -5 mm cut). The smallest amount of bone was in the tuber (minimum 0.2 mm; maximum 1.3 mm). Examination of the labio-palatal dimension demonstrated similar high thickness between 5-6 and 6-7 (minimum 3.7 mm at -11 mm cut; maximum 13.2 mm at -2 mm cut). The smallest amount of bone was recorded on the tuber (minimum 0.6 mm; maximum 4.1 mm). The following clinical applications are described: Closure of the extractions space, Symmetric intrusion of the incisors, Correction of the cant of the plane of occlusion and of the dental midline, Molar intrusion of one or two teeth, Molar distalization with the Distal Jet and miniscrews, Molar mesialization, Intermaxillary anchorage., Conclusions: the mechanical resistance of the miniscrews M.A.S. is suitable for their use in orthodontics. The best anatomical zones for their implantation are the interradicular spaces mesial to the first maxillary molars. From our experience to date, the miniscrews are a reliable and convenient system for skeletal anchorage when compared with other more invasive osseo-integrated systems.

The Author shows a system to dystalize the second upper molars and, if necessary, the third upper molars. This system, easy to be adapted, is made up by a palatal bar inserted between the first upper molars, by a sectional and a 100 grams precalibrated open Sentalloy coil spring used as an active force.

The Authors have prepared a protocol of research to evaluate the forces of lateral expansion expressed by the palatal bar et different degrees of activation. A special instrument has been built to this purpose. The forces expressed at the different degrees of activation are then evaluated and confronted in relation to the following variables: --length of the bar;--the presence or the absence of a U loop; --the more or less bowed conformation given to the bar. It is shown how, on the same terms, the presence of the U loop reduces the force made by the bar by about the half and that the more or less bowed conformation of the bar influences the force in the same way.

Repelling magnets have recently been proposed to move maxillary molars distally. Although the technique presents some clinical indications, the biomechanics of tooth movement with magnets has not been clearly investigated. The results of the Author's experience suggest that the repelling magnets mainly generate a tipping movement of the crowns on the sagittal plane. The distal-tipping of the molars represents almost 50% of the total effect, the mesial tipping of the bicuspids-cuspids-incisors constitutes the remaining 50%. Also, on the horizontal plane, the force generated by the magnets tends to rotate the crowns of the molars palatally.

Various biomechanical systems for the molar uprighting have been described. The Authors analyze the force system delivered on the molar and on the anchorage unit. The biomechanical considerations are emphasized in each single case.

The showed system has the peculiarity of having a coil spring as an active and continuous force. The anchorage is partly included into the system and only partly depends on the cooperation of the patient. The use of extraoral traction is optional, it is necessary only when an excessive molar tipping is noted. The system can be used in both symmetric and asymmetric distalization cases.

This work shows the results of mechanical strength tests effected over first superior bicuspids before endodontically treated. The Authors show the strength differences, in connection to the access-cavity, between endodontically treated and non-treated teeth. Finally it was found that the demolition of only one marginal ridge reduces the tooth strength to withstand the occlusal forces.

The orthodontic tooth movement produces physical and biochemical reactions in the periodontium. Tooth movements can be expressed by cell activation inducing bone resorption and remodelling. Substances as cAMP, cGMP, neuropeptides, prostaglandins and ormons play a basic role in this mechanism as mediators and modulators of the cellular responses. The Authors review the possibility to control the degree of the tooth movement acting on this biochemical process.

The Authors deal systematically with the transpalatal bar and lingual arch biomechanics. Particularly passive applications are distinguished from active ones. The Authors propose a classification of active applications based on the activation order (first, second, third), on the kind of biomechanics of the system (statically determinate or indeterminate) and on the symmetry or asymmetry of the activation. Every group of this classification is then analysed in detail.

The knowledge of force systems which are produced by orthodontic appliance is one of precondition for a rationale Orthodontic pretreatment. This article describes the force system developing when a straight wire is placed in two nonalligned brackets, to examine to typodont what is analysed by Burstone and Koenig in their study on six Classes.

The Authors assess, by SEM analysis, biomechanical and physical characteristics of lingual orthodontic appliances of Ormco CO. Each part of the bracket structure has been observed and assessed.

Shape memory alloys, which have the ability to be deformed into a temporary shape and then returned to its original shape giving useful elastic forces, are used in orthodontics field as shaped archs and springs. Their characteristics offer high potentiality to produce new orthodontics devices and to use in implantology. Using different analysis techniques with focussed electron beams, Authors have investigated on the superficial topography, alloy structural composition and on the absorbed elements of superficial layers of Nitinol orthodontics archs. SEM analysis have shown a compact and finished surface. PIXE analysis has quantized the atomic alloy composition in 55% and 45% on nickel and titanium, respectively. Auger spectroscopy and ion sputtering technique have shown that in surface of new archs oxygen and carbon are present up to about 300 A depth.

Orthodontics is based upon the cellular response to biomechanical forces. To better investigate about the manner in which cells respond to such forces, we have devised an experimental model to permit morphologic and metabolic characterization of human cells subject to a range of cyclic or static mechanical stimuli similar to those which may prevail in orthodontic-orthopedic therapy. The most recent data in the literature indicated that cyclic forces could have bigger effect on cells than continuous ones. To better understand the rationale of the cyclic force effect, a morphological study on human fibroblast was performed. We found that stretching or compression delivered an immediate and proportional deformation on cells. After 10-15 minutes the morphology of cells readapt to the new mechanical environment, this causing the lost of the biological activation. A new mechanical stimuli should be necessary to determine a new biological reaction.

Due to presence of rigid inorganic matrix, mechanical perturbations cannot affect the bone blood supply or deform osteocytes. Because convincing evidence that bone can directly perceive mechanical forces in lacking, we hypothesize that mechanical perturbations can only elicit remodeling by acting through a soft tissue envelope. These soft tissue envelopes are the periodontal ligament, periosteum, fibrous tissues that can form around implants, sutures and the like. Fibroblast, preosteoblast, and mesenchymal cells are composing the envelopes. It is possible that these cells are indeed responsible for bone remodeling subsequent to forces application.

The Authors studied a new photopolymerizing orthodontic bonding resin, Trans-Band of 3M. Many ad vantages of the resin were described and particularly the short photopolymerizing time, 20 seconds only, and the uniformity of bond strengths obtained by 20 tests, all higher than 10 Kg. So, the Authors propose to experiment clinically Trans-Bond and, if it had the same ad vantages, to make use of it in place of Concise, the most used composite in orthodontics.

A survey in made of the technologic and clinical characteristics of different types of intraoral elastics, through experimental tests, aimed overall at defining the possible difference of residual force between stretched out or non stretched out elastics before they are inserted in the mouth. Twelve patients, male and female, aged 10 through 14, were examined and elastics from three different manufactures were applied. The Authors conclude that the evidence obtained is reliable in the choice between the preliminary stretching out or non stretching methods in the clinical use of these elastics.

There is a necessary correlation between the Monson's curve, due to the mandibular kinematics, and the interalveolar axis' inclination in the different occlusal areas with unitary function. In the triturating area the verticality of the interalveolar axis is necessary for the stability of the cusp-fossa relationship in centric occlusion and for the stability of the prothesis during mastication. The Author shows the occlusal morphology and the arrangement of the prosthetic teeth in the different skeletal classes in relation to functional interalveolar strength's direction.

Partial removable prosthesis must foresee masticatory force distribution on all dental arch, with occlusal contacts uniformly distributed on natural and artificial teeth. These dental contacts must have the same intensity and they must happen in the same time, rispetting the gnathology laws. In this work it is investigated the possible utilization in partial removable prosthesis of T-Scan.

The principles of straight arch technique are described and the mechanical characteristics of contemporary pretorqued, preangulated "straight arch" appliances are summarized. A step wise approach is presented for efficient orthodontic tooth movement using sliding mechanics with .022" straight arch appliances. The steps are: 1) alignment and leveling; 2) molar correction and space closure; 3) finishing. Specific suggestions are made for wires and force elements best suited to sliding mechanics.

A craniomandibular structural asymmetry can be congenital or hereditary in nature, or can be acquired from traumatic of infectious events. During growth quantitative and qualitative alterations of the functional loads applied to the bones may modify their developmental pattern and lead to asymmetry: this has been show extensively through animals experiments. On the other hand, occlusal alterations may lead to mandibular displacement in maximum intercuspidation (ICP) and, consequently, to an apparent asymmetry. Therefore a distinction can be drawn among: 1) structural asymmetries; 2) displacement asymmetries; 3) mixed types. The different types of asymmetry may be diagnosed through the integrated analysis of the data from clinical examination, TMJ radiographs, teleradiographs and cephalometric analysis. A system is also presented, that analyzes the symmetry degree through Computer Aided Design. The purpose of treatment and the consequent treatment modalities vary in function of the type of asymmetry and the patient's age. When a mandibular displacement is present, it should be treated independently from the patient's age. However, if structural asymmetry is present, the treatment modalities depend on the patient's age. In the growing individual it is possible to exploit the potential modeling during growth and to modify through orthopedic means the residual growth of the patient. However, in the adult patient structural asymmetry can not be managed any more through conservative orthopedics.

Prosthetic rehabilitation in cases of short dentition raises difficult problems, because a support must be found for free-end denture bases on both the edentulous crest and the remaining teeth. A prosthesis employing a wire device for the damping and distribution of forces and thus better able to supply this mixed support is described. Overloading of the abutments is avoided, along with the excessive reabsorption of the alveolar crest caused by classic damped appliances. Clinical experience in a series of cases treated over a period of ten years points to the effectiveness of this type of prosthesis.

The authors have reported about the different dental erosions in depth detected in the right and left side of dental arch. The authors have considered the relation about dental erosions and the muscular strength applied by hand and arm.

The cementation is a basic step in the fixed prosthesis rehabilitation. Therefore, it is very important to know the main chemical, physical and biological properties of luting cements. The tensile strength of some dental cements for fixed cast restorations has been studied. Results obtained showed that glass ionomer and zinc oxide-eugenol with Eba are better than the other dental cements. The difference between the data obtained showed to be statistically significant.