Lia Rimondini

Surface enamel remineralization: biomimetic apatite nanocrystals and fluoride ions different effects

A new method for altered enamel surface remineralization has been proposed. To this aim carbonate-hydroxyapatite nanocrystals which mimic for composition, structure, nanodimensions, and morphology dentine apatite crystals and resemble closely natural apatite chemical-physical properties have been used The results underline the differences induced by the use of fluoride ions and hydroxyapatite nanocrystals in contrasting the mechanical abrasions and acid attacks to which tooth enamel is exposed. Fluoride ions generate a surface modification of the natural enamel apatite crystals increasing their crystallinity degree and relative mechanical and acid resistance. On the other hand, the remineralization produced by carbonate-hydroxyapatite consists in a deposition of a new apatitic mineral into the eroded enamel surface scratches. A new biomimetic mineral coating, which progressively fills and shadows surface scratches, covers and safeguards the enamel structure by contrasting the acid and bacteria attacks.

Dental implants placed in grafted maxillary sinuses: a retrospective analysis of clinical outcome according to the initial clinical situation and a proposal of defect classification

OBJECTIVE OF THE STUDY To present a classification of maxillary defects necessitating sinus floor elevation procedures (SFEPs) with two objectives: (a) to propose a standardization of surgical procedures according to initial type of atrophy and (b) to allow the evaluation of the success/survival rates of implants placed in the grafted areas according to the initial situation. MATERIALS AND METHODS Nine-hundred and fifty-two consecutive SFEP were performed on 692 patients. Initial defects were classified according to a new classification, which considered not only residual bone height below the sinus but also the width of the alveolar crest and horizontal/vertical intermaxillary relationship. Results were evaluated according to the different classes. The sinuses were grafted with autogenous bone taken from intra-oral or extra-oral sites: 579 SFEP were associated with vertical and/or horizontal onlay grafts to correct concomitant alveolar ridge deficits. A total of 2037 implants were inserted into the grafted sinuses either immediately or 4-6 months later. Three to 6 months afterwards, implants were loaded. The mean follow-up was 59 months (range: 12-144 months). RESULTS The success rate of the reconstructive procedures varied between 93.2% and 100%, according to class of atrophy; the overall survival and success rates of implants were 95.8% and 92.5%, respectively, whereas the survival and success rates according to class of atrophy varied between 90% and 97.6%, and between 85.4% and 95.5%, respectively. Lower success rates were found in classes presenting with more severe atrophy. CONCLUSION The results obtained demonstrated that sinus floor elevation, alone or in association with reconstructive procedures with autogenous bone grafts, is a reliable procedure to allow implant placement in atrophic edentulous maxillae, irrespective of the initial clinical situation. However, it must be underlined that the success rates of reconstructive procedures and implants differ according to class of atrophy, showing lower success rates in classes presenting with more severe atrophy.

Intermittent exposure to ethanol vapor affects osteoblast behaviour more severely than estrogen deficiency does: In vitro study on rat osteoblasts

With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to increase all over the world. Habitual excessive alcohol consumption is associated with pathological effects on bone. The aim of the present in vitro study was to investigate comparatively the proliferation and synthetic activity of osteoblasts (OB) isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapor, sham-aged rats and long-term estrogen deficient rats. Cell proliferation (WST1) and synthesis of alkaline phosphatase (ALP), osteocalcin (OC), collagen I (CICP), transforming growth factor beta1 (TGF-beta1), interleukin-6 (IL-6), tumor necrosis factor alfa (TNFalpha) were measured at 3, 7 and 14 days of culture. Osteoblast proliferation rate and TGF-beta1, IL-6 and TNFalpha syntheses were significantly affected by alcohol exposure. Estrogen deficiency and alcohol consumption share many common pathophysiological mechanisms of damage to bone, but alcohol affects OB proliferation and TNFalpha synthesis significantly more than menopause does. Therefore, these in vitro data suggest that alcohol has even more deleterious effects on bone than estrogen deficiency does.

Temporomandibular disorders due to improper surgical treatment of mandibular fracture: clinical report.

Abstract: A case of mandibular fracture surgically consolidated in a wrong position resulting in craniomandibular disorders is reported. The inadequate surgical alignment of the healed bony segments caused a malocclusion. This changed the original neuromuscular system such that compensatory mechanisms began to change the whole balance of the organism. The patient presented a mandibular crossbite, an asymmetry of the face, and extensive alteration of muscular, articular, and postural function. The bony malunion and malocclusion were treated using an interdisciplinary surgical-orthodontic treatment for correcting functional disorders and aesthetic deformity. Electromyography and computerized mandibular scanning were used to evaluate improvement of the muscular activity, during rest and function, and of the mandibular kinesiology. Timing of surgical treatment and adequate fixation and immobilization of fracture segments are very important to avoid complications such as infection, delayed union, nonunion, malunion, skeletal discrepancies, nerve injury, and (rarely) ankylosis. The surgical approach should be based on the general criteria of traumatologic therapy, restoring the original bone shape and the right occlusal relations as soon as possible.

Dental Tissue Engineering: a New Approach to Dental Tissue Reconstruction

Caries, trauma, erosion and periodontal disease are pathologies characterized by the damage and loss of dental tissues and sometimes loss of the whole tooth. These groups of diseases are very common and affect millions of people worldwide in both developing and industrialized countries. Restorations of damaged tooth tissues and substitution of missing teeth with artificial prostheses represent the traditional therapeutic solutions. Although many sophisticated biomaterials are now available for restoration, their use is not yet completely satisfactory. Implants, crowns, bridges and any kind of restorations are generally less functional, durable and aesthetic than intact teeth and they are aimed at repairing rather than regenerating tissues. In addition, the economical impact of such kind of therapeutic approaches is notable. The World Health Organization estimated that the dental treatment costs accounted for 5-10% of healthcare budgets in industrialized countries and adjunctive costs may be considered in terms of absences from work (Petersen, 2003). In the last few decades the process of tooth mineralization and the role of molecular control of cellular behaviour during embryonic tooth development have received much attention. The knowledge gained in these fields has improved the general understanding about the formation of dental tissues and the whole tooth and set the basis for teeth regeneration. The present chapter is divided as follows:

Biofilm formation on implants and prosthetic dental materials

The human body is subdivided into niches containing a wide variety of commensal microorganisms with essential functions for the host’s health. When the balance of the resident microflora changes, pathological conditions may occur. Based on this premise, this chapter first describes the composition of one of these niches, the oral cavity: its oral microbiome and the most frequent biofilm-related medical device infections promoted by multidrug-resistant strains, the so-called super bacteria or super bugs. In this context, the discussion focuses on the key events that unbalance the microbiome homeostasis and induce commensal bacteria to biofilm formation and describes how metabolites can influence the prevalence of bacterial species within the microbial community, thus promoting the onset of infectious diseases. As implantable devices are increasingly being used in dentistry, as in other medical fields, there is a pressing need for control strategies, able to counteract the events involved in biofilm formation, especially the adhesion phase, in order to reduce the occurrence of infection-associated implant failures. In this connection, the second part of this chapter briefly examines currently available strategies and the role of chemistry in biofilm prevention: the development of materials with intrinsic antibacterial properties, bioactive coatings with bactericide agents or materials delivering antibiotics, and nanostructured anti-adhesion surfaces or anti-biofilm bioactive molecules. Emerging and future approaches to fight biomaterial-associated infections are still to be clarified.