Temporary anchorage devices (TADs) in orthodontics: review of the factors that influence the clinical success rate of the mini-implants.

INTRODUCTION: The mini-implant, temporary anchorage devices (TADS), are now a common method of treatment in Orthodontics with versatility, minimal invasiveness and the relationship between costs and benefits that they offer even today. Skeletal anchorage has, to a large degree, replaced conventional anchorage in situations where anchorage is considered either critical, insufficient, or likely to result in undesirable side effects such as vertical displacements generated by inter-maxillary force systems. OBJECTIVES: The objective of this study is to carry out a review about the factors that seem affect the success or failure rate of orthodontic mini-implants. A computerized literature review was performed by searching the MEDLINE database (Entrez PubMed, www.ncbi.nlm.nih.gov), Google Scholar, Scopus, Cochrane Central Register of Controlled Trials, Isi Web of Knowledge until March 2016 . The main subject heading "orthodontics" was combined with these keywords mini-implant, mini-screw, micro-implants, mini-implant success rate, mini-implant failure rate, skeletal anchorage, temporary anchorage device (TADS). In the selection process, abstracts were initially read independently by two researchers to identify potentially eligible full text papers which were then retrieved and assessed in order to decide on the final inclusion. CONCLUSIONS: The clinical success of orthodontic anchorage by mini-implants depends on the stability of the miniscrews used for fixation. For good stability, the application site must provide bone of good quantity and quality. We can reasonably assume that the stability of the anchorage of the mini-implants could be optimized by selecting a position with particular characteristics of quality and quantity of bone, in relation to cortical and total mandibular and jaw bone thickness. These expected informations are important because they indicates that the bone quality and quantity are significant when considering an implant placement site, but also that there are other confounding factors influencing the success rate.

The effects of host derived metalloproteinases on dentin bond and the role of MMPs inhibitors on dentin matrix degradation.

OBJECTIVES: The work has the objective to analyze the literature on the degradation of the adhesive interface. In particular the study is focused on the role of the metalloproteinase in the hydrolytic degradation of collagen matrix in the bonded interface. The survey will concern also the latest innovations to improve and increase the link between dentin and the restorative materials through the MMPs inhibitors. METHODS: The research has been carried out in the MEDLINE database by choosing keywords as "metalloproteinases" and "dentin bond" and "degradation". In vitro studies were included in the research, excluding studies with no human and deciduous teeth. Language was limited to English. RESULTS: The collagenolytic enzymes in mineralized dentin have been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. CONCLUSION: The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability.

Periodontal bacteria in the genital tract: are they related to adverse pregnancy outcome?

One of the most important factors implicated in preterm birth (PTB) is acute genitourinary tract infection. The bacteria causing chronic periodontal inflammation include Gram-negative rods and anaerobes similar to those found in women with bacterial vaginosis. The aim of this prospective study is to investigate the relationship between oral and vaginal microflora and preterm low birth weight. Real-time polymerase chain reaction was used to detect both the presence and level of six periodontitis-related species: Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Fusobacterium nucleatum ssp(Fn), and Prevotella intermedia (Pi) for both oral samples of subgingival plaque and cervical samples, obtained from 80 patients, during gynaecological examinations. The more representative oral pathogen (less than 60 percent) species in oral samples of preterm and term group were Tf, Td, and Fn. 24.4 percent of pregnant women presented periodontal pathogens in vaginal swab; the most representative species with a percentage over 0.1 percent of total bacteria in genital tract of preterm group were Tf, Td, and Piwith a positive correlation (less than 0.5). The presence of the bacterium T. denticolain the vagina, regardless of the amount, adversely affects preterm delivery.

Traditional elastic ligatures versus slide ligation system. A morphological evaluation.

OBJECTIVE: Elastomeric materials play an important role in the orthodontic practice, including the retraction force to move teeth into extraction sites, closing diastemas, selective shifting of the midline and generalized space closure. Frictional resistance and ligating strength of archwire-bracket-ligature complex occurs during utilization of elastomeric and metallic ligatures when orthodontic forces are applicated. The aim of this study was to analyze elastic deformation of three types of elastomeric ligatures, after clinical use. MATERIAL AND METHODS: ELASTOMERIC LIGATURES: ring-shape, transparent, latex ligatures (Leone® S.p.A.), ring-shape, grey, polyurethane ligatures (Micerium® S.p.A.) and grey, polyurethane, Slide low-friction ligatures (Leone® S.p.A.). A total of 9 orthodontic patients undergoing fixed orthodontic therapy were selected. Three specimens were applied, one for each types of ligature, inside the oral cavity of each subject. Samples were kept in the oral cavity for 28 days, ligating 0.16 X 0.22 inches stainless steel archwires to stainless steel premolars brackets (Leone® S.p.A., Sesto Fiorentino, FI, Italy) for Bidimensional technique. After the pre-established time, the systems of ligature were removed and washed. Control group consisted of 9 unused specimens of each ligation type. Each elastomeric ligature was observed under the scanning electron microscope (SEM) to determine variations in size. The archwire-bracket-ligature complex was also analyzed. RESULTS: Transparent O-ring ligatures showed significant volumetric and structural changes. The external rounded shape was rather maintained, while the internal shape tended to appear square. Both external and internal diameter significantly increased (p<0.005 and p<0.0001 respectively) while the thickness decreased ( p<0,005) when analyzed with t-test. Polyurethane ring-shape ligatures retained the initial ring design. Both external and internal diameter increased (p<0.0001), while the thickness remained almost unchanged. The internal border was more squared, and showed jagged edges with continuous and irregular extroversions. Grey, polyurethane Slide low-friction ligatures showed a reduced dimensional change. There was a slight increase in two dimensions, length and width, (14-16%) (p<0.05 and p<0.001) while there was a not significant decrease in thickness (10%). CONCLUSION: From SEM analysis of ligature morphology it emerges that latex and polyurethane O-ring ligatures endure significant volumetric and structural changes, after clinical use, index of a greater degree of friction and early loss in functionality. Grey, polyurethane Slide low-friction ligatures presented limited variation in size after clinical use.

Sealants in dentistry: a systematic review of the literature.

UNLABELLED: The occlusal surface is the most affected area by dental caries and the sealing of the pits and of the fissures has been found, in time, the preventive method most effective trying to counteract the onset. Currently, the WHO considers it as a primary preventive measure, in other words one of the most effective and least invasive available to ensure the complete protection and the total preservation of the occlusal carious by the phenomenon. PURPOSE: THE AIM OF THIS WORK HAS BEEN TO PERFORM A SYSTEMATIC REVIEW OF THE LITERATURE ON CLINICAL TRIALS OF DIFFERENT SEALING MATERIALS, IN ORDER TO: compare their individual characteristics, highlight the reliability and the long-term efficacy and identify the most significant variables, both technological and clinics, in order to declare whether or not the success of this method prior. MATERIALS AND METHODS: The research has been carried out in the MEDLINE database by choosing keywords as "sealants" and "follow up". Only studies published in the last thirteen years have been considered and have been evaluated only types of scientific articles that fall within the definition of Anglo-Saxon "Clinical Trial" and "Controlled Clinical Trial", excluding all experimental works in vitro, case-reports, meta-analyzes and literature reviews. Have been also considered only scientific papers on patients between the ages of 0 and 18 years. RESULTS: Out of 29 studies, evaluating a total of 2900 individuals (aged between 2.5 and 17 years), 7411 seals made by using resin-based sealants (RB Sealants), modified glass ionomer sealants (RMGI) and compomer sealants have been analyzed. The best retention capacity of the material in time has been obtained from the use of RB Sealants compared to RMGI, demonstrating retention values much lower with partial loss of material at a distance of one year from the clinic. The compomers demonstrate retention values intermediates. The incidence of caries in a year is negligible for all sealants application. CONCLUSIONS: In terms of retention, resin-based sealants (RB Sealants) are the materials that give more guarantees of success at 12 months, while in the same period there haven't been significant differences in caries prevention of disease among the various classes sealing materials analyzed.

Plaque retention on elastomeric ligatures. An in vivo study.

UNLABELLED: Fixed orthodontic appliances make it difficult to maintain the oral hygiene, resulting in plaque accumulation. Retention of bacterial plaque, represents a risk for white spot lesions and development of periodontal disease. AIM: Purpose of this study was to determine in vivo the retention of plaque on three different elastic ligatures, in comparison with stainless steel ligature, to determine a possible association between type of ligatures and accumulation of microorganisms. MATERIAL AND METHODS: THREE ELASTIC LIGATION SYSTEMS WERE ANALYZED FOR PLAQUE RETENTION: ring-shape, clear, latex ligatures (Leone® Spa), ring-shape, grey, polyurethane ligatures (Micerium® Spa) and grey, polyurethane, Slide low-friction ligatures (Leone® Spa), compared with stainless steel ligatures (Leone® Spa) used as control. Forthy orthodontic patients undergoing fixed orthodontic therapy were selected. A sample for each type of ligature were applied inside the oral cavity of each subject. Samples were kept in the oral cavity for 28 days, ligating 0.16 X 0.22 stainless steel archwire to stainless steel orthodontic premolars brackets. The presence of bacterical slime was quantified by spectrophotometric method (crystal violet-Bouin's fixative) and morphological observations was evaluated by Scanning Electron Microscopy (SEM). RESULTS: From analysis of bacterical slime emerges that all the elastics showed a low plaque retention, especially if compared to the group of steinless steel ligatures, that presented a greater plaque adhesion, statistically significant compared to the Slide group (r<0.0002) and the two elastic groups (r<0.0001). This study reported no significant difference between the Slide ligatures and the traditional elastic ligatures as regards the retention of plaque. SEM images showed presence of cocci, rods and few filamentous organisms and an interbacterial matrix in all observed samples. CONCLUSION: Elastomeric ligatures showed a significant lower susceptibility to plaque adhesion, in comparison to the stainless steel of the metallic ligatures. No statistically significant difference was observed among the elastic devices.

National Italian Guidelines for caries prevention in 0 to 12 years-old children.

AIM: Oral and dental health improved tremendously over the last fifty years in Italy but still prevalence of dental caries in children remains a significant clinical problem. This report describes the National Italian Guidelines for caries prevention. METHODOLOGY: A panel of experts coordinated by the Italian Society of Paediatric Dentistry (SIOI) planned to elaborate the national Italian guidelines for caries prevention in children. The structure of the guidelines has been planned to follow the principles of modern caries treatment and management as well as science based dentistry. The main procedure was based on a hierarchic evaluation of literature. CONCLUSION: The guidelines are planned for dentist working in primary dental care, however, they are also designed to be of interest for other care professionals such as paediatricians, gynecologists, pharmacists and general medical practitioners and also for parents and/or guardians of the children.

Growth of osteoblast-like cells on porous hydroxyapatite ceramics: an in vitro study.

Blocks of two porous synthetic hydroxyapatites (HA) with porosity fraction of 30-40 and 50-60 vol%, respectively and a coralline derived porous HA were evaluated in vitro in presence of the osteogenic line MC3T3-E1 and of L929 fibroblasts. The two tested biomaterials did not affect cellular proliferation (MTT test), but the contact inhibited alkaline phosphatase activity. Porous aggregates resulted perfectly biocompatible in the tests performed, since observations performed by light microscopy did not show any cell morphological change, osteoblast presented a stellar shape and typical pseudopodes. SEM observations showed intercellular matrix containing fibers on HA-based porous aggregates.

Thin sections for hard tissue histology: a new procedure.

We describe a simple method by which thin sections ( approximately 100 microm) from modern and archaeological teeth and bones can be obtained. A detailed embedding-cutting-mounting procedure is proposed, suggesting the use of a dental adhesive system, composite resins and conventional embedding resins, with the aims of improving the quality of the sections and substantially reducing the steps and time needed to prepare specimens for histological analysis. The introduction of this dental materials-based system allows an accurate positioning of the sample embedded inside the resin, prevents cracks and distortions of the section during the cutting phase and generally improves mounting sections on slides.

Gingiva, teeth and sea salt.

This article presents a review of the effects of sea salt on gingival tissues. The beneficial effects of sea salt are described.

Bacterial adhesion to dental alloys. The role of the surface and composition.

BACKGROUND: In the oral cavity, many bacteria can only survive by adhering to hard surfaces. The roughness and free energy of these surfaces play an important part in this process. Precision dental alloys may undergo corrosion, but findings show that this does not seem to cause problems of biocompatibility. The release of metallic ions into the oral cavity may both inhibit bacterial growth and influence bacterial adhesion. The object of the present study was to bring to light any possible correlation between corrosion and/or ionic release and bacterial adhesion with regard to 18 different types of dental alloy, both before and after polishing. METHODS: Electrochemical analyses were carried out (cyclic potentiodynamic and potentiostatic polarisation tests). Corrodible elements were analysed through Atomic Absorption Spectroscopy of specimens of each alloy. The inhibition of bacterial adhesion and growth was determined using bacteria specific to the oral cavity. RESULTS: All the alloys examined show a tendency towards spontaneous passivation with low values of anodic current. The evaluation of ionic release confirmed the biocompatibility of the tested materials and the solutions conditioned with the alloys did not inhibit bacterial growth. There was no significant bacterial adhesion after polishing. Bacteria adhere to unpolished alloys in a specific manner and are inhibited from doing so in the presence of alloys for gold-resin restorations containing silver and copper. CONCLUSIONS: When polished, all the alloys are resistant to in vitro electrochemical corrosion and bacterial adhesion. The possibility cannot be excluded that bacterial adhesion occurs after the materials have been in place in the oral cavity for some time. The alloys which were found to inhibit bacterial attack may be more suitable, while not representing a biological risk for the surrounding tissues.

[Necessity and validity of standard models for experimental preclinical evaluation of biomaterials. An example of biologic characterization of a hydroxyapatite-based implant material]. / Necessità e validità di modelli standard per la valutazione sperimentale preclinica dei biomateriali. Un esempio di caratterizzazione biologica di un materiale da impianto a base di idrossiapatite.

A large number of methods are now available for the preclinical screening of implantable materials concerning their biocompatibility and their ability to stimulate tissue formation. In vitro techniques represent a very useful tool, since this way we can realistically simulate the biological events which occur in vivo at the bone-implant interface. In the present study scanning electron microscopy and light microscopy observations were performed in order to assess the effect of an hydroxyapatite granulate on cell behaviour and morphology. Uptake of proteins to hydroxyapatite surface has been also investigated by comparing the amounts adsorbed after incubation with bovine serum albumin and bovine pancreaticamilase. According to our preliminary observation cells do not show signs of toxicity or inhibition of cell growth even after 14 days of co-culture with hydroxyapatite. Granules were covered by an uninterrupted cell layer by day seven. Even after two days micrographs show cells anchored and spread over the surface of the underlying granules, with a flattened and stellate shape. Such a morphology indicates a very high cellular activity, suggesting that the interaction with hydroxyapatite seriously increased metabolism. Measurements of protein adsorption on the hydroxyapatite surface show that changes in the size of particles affect the binding of proteins, while, in the case of granular hydroxyapatite, despite changes in size of granules, variations of protein adsorption were not observed, neither in relation to their different isoelectric point. Our preliminary results represent a good example of the opportunities presented by an experimental in vitro model.

Oxygen transport by fetal bovine hemoglobin.

The functional properties of fetal bovine hemoglobin have been studied as a function of temperature, chloride and 2,3-diphosphoglycerate (DPG) concentration. The fetal bovine erythrocyte has six times the concentration of the allosteric modulator DPG compared with the adult cell, and yet the oxygen affinity of the fetal hemoglobin still exceeds that of the adult molecule at the respective physiological concentration of DPG and at physiological temperature. We find that the allosteric modulator strongly affects the enthalpy of oxygen for the fetal hemoglobin but not for the adult protein. We propose that this may be an important mechanism for the exchange of heat from mother to fetus. In particular, under stripped conditions the oxygen affinity of fetal bovine Hb is considerably higher than that of the adult hemoglobin. Due to the higher DPG concentration that characterizes fetal bovine erythrocytes this difference is almost abolished in the presence of the respective physiological concentration of DPG and at 20 degrees C. However, on going from 20 degrees C to 37 degrees C, the difference in O2 affinity between the two hemoglobins is restored, as it should if oxygen has to be transferred from maternal to fetal blood, by virtue of the lower overall heat of oxygenation (delta H) displayed by fetal Hb when in the presence of DPG at physiological concentration. This behavior is reminiscent of that of human fetal Hb and outlines the role of temperature and of its interplay with heterotropic ligands in the modulation of hemoglobin function to fully meet the physiological needs of the organism.

Hemoglobin function under extreme life conditions.

Considering the variety of species that depend on hemoglobin for oxygen transport, these molecules must execute their primary function under extreme environmental conditions. Hence, a thermodynamic analysis of oxygen binding with hemoglobins from different species reveals a series of adaptive mechanisms which are based on the thermodynamic connection between the binding of heterotropic effectors and the reaction with oxygen. The examples reported, from fishes to human fetus, illustrate how evolution can alter the structural basis of the heterotropic interactions to optimize the oxygenation-deoxygenation cycle in dependence of the physiological needs of the particular organisms. Moreover they show that a thermodynamic analysis of the reaction with oxygen overcomes the meaning of a detailed structural and functional characterization going deeper into the physiology of the specific organism.

Adaptation to extreme environments: structure-function relationships in Emperor penguin haemoglobin.

The functional properties of the single haemoglobin (Hb) of Emperor penguin (Aptenodytes forsteri) have been investigated at different temperatures as a function of proton and organic phosphate concentration. The complete amino acid sequence has been established. Comparison with that of human HbA shows 12 substitutions in the contact regions of alpha beta dimers. In addition to overall similarities shared with most of the avian Hbs previously described, this Hb shows significant differences, which could be related to the peculiar behaviour of this penguin. In particular we may consider that: (1) the shape of the Bohr effect curve seems well adapted for gas exchange during very prolonged dives, preserving penguin Hb from a sudden and not controlled stripping of oxygen; (2) the very minor enthalpy change observed at lower pH could be an example of molecular adaptation, through which oxygen delivery becomes essentially insensitive to exposure to the extremely low temperatures of the environment. Moreover, the small alkaline Bohr effect has been found to be only chloride-linked, since the pH dependence of the oxygen affinity is totally abolished in the absence of this ion. These functional characteristics are discussed on the basis of the primary structure of alpha and beta-chains.

Synergistic modulation by chloride and organic phosphates of hemoglobin from bear (Ursus arctos).

The oxygen binding properties of hemoglobin (Hb) from brown bear (Ursus arctos) have been studied focussing on the effect of heterotropic ligands, and the behaviour has been compared with that of human HbA, taken as a prototype of mammalian Hbs. It has been observed that in bear Hb chloride ions and 2,3-diphosphoglyceric acid (Gri(2,3)P2) can modulate the oxygen affinity in a synergistic way such that their individual effect is enhanced whenever they are both present in saturating amounts. The thermodynamic analysis of such a feature indicates that in bear Hb there are two classes of chloride binding sites, one acting synergistically with Gri(2,3)P2 and another one, which likely overlaps with the organic phosphate interaction cleft, and is therefore fully operative only in the absence of Gri(2,3)P2. The behaviour of the last site is similar to that observed in human HbA, where the effect of Cl- and Gri(2,3)P2 is mutually exclusive. The interaction energy between chloride and Gri(2,3)P2 synergistic binding sites appears to be O2-linked so that the interplay may have a relevant physiological role in modulating the oxygen transport in brown bear. This behaviour is associated with a marked pH-dependence of the oxygenation enthalpy in bear Hb, such that under acidotic and hypercloruremic conditions, oxygen supply to peripheral tissues could be maintained essentially unaltered even under low temperature conditions.

Functional, spectroscopic and structural properties of haemoglobin from chamois (Rupicapra rupicapra) and steinbock (Capra hircus ibex).

The functional and spectroscopic properties of chamois (Rupicapra rupicapra) and steinbock (Capra hircus ibex) haemoglobin (Hb) have been studied with special reference to the action of allosteric effectors and temperature. Moreover, the amino acid sequences of the N-terminal segments of the alpha- and beta-chains have been determined. The present results indicate that chamois and steinbock Hbs display a low affinity for O2, which appears to be modulated in vivo by Cl- ions rather than 2,3-bisphosphoglycerate. The Bohr effect for O2 binding to chamois and steinbock Hb is higher than for reindeer and bovine Hbs, being similar to that of human Hb. Moreover, the temperature-dependence of oxygenation appears intermediate between that of human and reindeer Hbs. E.p.r. and absorption spectroscopic properties of the ferrous nitrosylated derivative of chamois and steinbock Hbs suggest that both haemoproteins are in a low-affinity conformation even in the absence of InsP6. The reduced effect of polyphosphates on the functional and spectroscopic properties of chamois and steinbock Hb agree with amino acid differences in the N-terminal segment of the beta-chains (i.e. the deletion of Val(NA1) and the replacement of His(NA2), present in human Hb, and Gln(NA2), present in horse Hb, by Met). The molecular mechanism modulating the basic reaction of O2 with chamois and steinbock Hb may be linked to specific physiological needs related to the high-altitude habitats of these two animals.

Physiological relevance of the overall delta H of oxygen binding to fetal human hemoglobin.

Human fetal hemoglobin is known to display, at 20 degrees C, a lower affinity than human adult hemoglobin for oxygen when both proteins are in the absence of organic phosphates. The physiologically important reverse situation is achieved at 37 degrees C upon addition of 2,3-bisphosphoglycerate (DPG), whose lower effect on fetal hemoglobin is related to some amino acid substitutions present in gamma-chains. However, the difference in oxygen affinity observed at 37 degrees C is not solely due to the different modulation power of DPG with respect to adult and fetal hemoglobins. In fact, the results presented here reveal new aspects linked to the interplay of temperature and organic phosphates. In particular, the lower effect of DPG on fetal hemoglobin renders almost identical the oxygen affinity of the two hemoglobins at 20 degrees C, abolishing the difference observed in the absence of the effector. Successively on going from 20 degrees C to 37 degrees C, by virtue of the lower overall heat of oxygenation (delta H) displayed by fetal hemoglobin when in the presence of DPG, adult hemoglobin shows a lower oxygen affinity, as it should if oxygen has to be transferred from maternal to fetal blood.