Horia Octavian Manolea

Thermal behaviour and antimicrobial assay of some new zinc(II) 2-aminobenzoate complex compounds with bioactive ligands

New zinc(II) 2-aminobenzoate complexes with general formula Zn(2-NH2benz)2(L)2 (where 2-NH2benz is 2-aminobenzoate, and L is phenazone, N-methylnicotinamide, nicotinamide and isonicotinamide) were prepared and characterized by elemental analysis and by FTIR spectroscopy. The stability and thermal behaviour of the compounds were studied by thermal analysis techniques (TG/DTG, DTA), and the decomposition reactions were proposed. The decomposition of the studied compounds is always a multistep process, when after the release of the bioactive ligand, 2-aminobenzenecarbaldehyde, 2-aminobenzene and carbon dioxide were evolved. The solid intermediate compounds were confirmed by FTIR spectroscopy, and the volatile products were identified by mass spectrometry. The final solid product of thermal decompositions was zinc oxide, which was confirmed by XRD and FTIR analysis. The non-isothermal kinetic investigation of Zn(2-NH2benz)2(mnad)2 decomposition in air was performed by means of isoconversional methods, for a better understanding of the undergoing processes. The antimicrobial assay was carried out comparatively for the investigated compounds; they have higher biological activity towards Staphylococcus aureus, Escherichia coli and Candida albicans in comparison with zinc(II) 4-bromobenzoates.

Zirconia Biocompatibility in Animal Studies - A Systematic Review

Zirconia is a metal used in dental implantology. Its biocompatibility was studied in vitro and in vivo, results of the studies being analyzed in reviews and meta analyses. The aim of this systematic review was to evaluate biocompatibility of zirconia in animal studies in vivo expressed as results of histomorphometric tests. Databases were searched from 1980 until February 2016, with different combination of the following MeSH terms: zirconium, biocompatibility, dental implants, in vivo, animal studies. Letters to the editors, case reports, commentaries, review articles and articles published in other languages then English were excluded. The search of PubMed, ScienceDirect and Google Scholar databases yielded 690 titles. After abstract screening and duplicate discarding 50 articles were identified and finally, 40 were included in the review. Most of the studies compared zirconia with titanium, a well established material for dental implants. In majority of the studies zirconia showed a similar osseointegration with titanium. Surface implant treatments, like sandblasted and etched zirconia (ZrO2-SLA), alumina toughed zirconia (ATZ), and powder injection molding (PIM) were used to improve osseointegration of zirconia with good results. In the light of histomorphometric test, zirconia, no matter physical and structural forms tested, is a biocompatible material.

Study on gingival tissue reaction to the materials used for making dental prosthesis

Abstract Fixed prosthetic restorations may generate periodontal irritation by various and complex mechanisms especially in the presence of the microbial factor. In this regard, changes that compromise the functional value of the support structures of the teeth occur. Studies on patients wearing fixed denture show that those prosthetic structures facilitate plaque accumulation. Close supervision leads to prevention of periodontal diseases, through learning of a proper hygiene. Between the marginal periodontium and the prosthetic restoration, there must be a relation of ‘mutual protection’ or at least ‘mutual respect’. In this study, we tried to analyze the reaction of the periodontal tissue in contact with fixed prosthesis depending on the prosthetic material used. There were 102 fixed prostheses considered by this study that have generated reactions in the periodontal tissues with which came into contact. Thus, from the total number of 102 fixed dental prostheses, 75% were made from metal alloys based on copper, 18% from Cr–Ni alloys, 2% from Cr–Co alloys, 4% from gold alloys, and one from stainless steel. In 35% of the cases, the patients had multiple fixed dentures made from different types of dental alloys, cases in which the symptoms of the periodontal problems may be also linked to the phenomenon of oral galvanism. The histological study showed various morphological changes from one patient to another, depending on the intensity of the inflammatory and reparative response, the associated diseases (diabetes, dyslipidemia, cardiovascular diseases) and especially on the dental hygiene status. Fixed prosthesis, in the absence of a proper cervical adaptation and an adequate local hygiene, may act as an irritative thorn and may induce gingivitis and periodontitis phenomena.

The Clinical Approach in A Case of An Endodontic Therapeutic Failure At Upper First Molar Level (Clinical Case)

The persistence of functional teeth on the arch for a long enough period of time represents an accomplished goal due to the existence and constant improvement of the conservative means of treatment. The misapprehension regarding the complexity of endodontic space is one of the various failures of the endodontic treatment. The aim of this article is to emphasize the clinical approach of a retreatment case of endodontic therapeutic failure at upper first molar level. First, it would be preferable to try an orthograde endodontic retreatment because this is the most conservative way of treatment. Keywors: upper fist molar, endodontic space, orthograde endodontic retreatment

Current Options of Making Implant Supported Prosthetic Restorations to Mitigate the Impact of Occlusal Forces

The lack of a periodontium for a dental implant may lead to high stress concentration at the bone level when the implants are prosthetically loaded. The present paper discusses the current possibilities of implant supported prosthesis making in order to mitigate the impact of occlusal forces. The cement layer may serve as an absorber for the strain, but its role is reduced and poses the risk of excess cement retained in the peri-implant tissue. The use of resin materials for the implant supported prosthetic restorations veneering it has been suggested for many years, but their role it is important in the case of full-arch fixed implant-supported prosthesis with cantilever distal extensions and less in single implant restorations. Nowadays, new materials like fiber-reinforced composites and high-performance polymers as PEEK may be used for the framework of the implant supported prosthetic restorations, but also for the implant or the prosthetic abutment realization.

The Importance of the Magnification Use for the Additional Root Canals Localization at the Second Maxillary Molars

The aim of this study is to highlight the morphology of the second maxillary molars root canals and to draw a comparison between the data obtained with and without magnifying means. The study covered a total of 31 extracted human second maxillary molars. After being examined by a thorough physical exam and an X-ray examination, teeth were trepanned in the place of election. Thereby the access cavity was performed using: a) for the stage of pulp chamber ceiling penetration, a globular diamond bur for the turbine, b) for the stage of broadening access cavity, a cylindrical bur inactive in the head for the opposite-angle piece and c ) a Batt bur for the flaring and finishing stage.Afterwards, the sighting of the main root canals was performed using the endodontic probe or Miller file. Examination and sighting of the additional canals was made under magnification using the dental microscope. The molars with three canals had the highest prevalence of endodontic morphology of two upper molars (90.32%). But there were special cases with two channels morphology (6.45%) and four channels morphology (3.22%). After examining the endodontic space under the microscope, there have been identified and secondary canals, approximately 32.25% of molars examined presenting one or more secondary canals. The anatomy of the most frequent upper second molar was three roots with three root canals; the most common variation in morphology is the presence of an mesiobuccal additional canal (MB2). However, we can encounter an unusual number of canals. The importance of magnification, of the dental microscope in our study cannot be ignored because using only the latter we could highlight the real endodontic morphology of the two upper molars extracted examined, finding additional canals in 32.25% of the molars undergoing examination.

Bioceramics and Endodontics: Present and Expectations in Clinical Use

Currently bioceramics are preferentially used in various endodontic treatments such as pulp capping, pulp amputation, apexification, root-end fillings, perforation repair, and pulp regeneration. Additionally, bioceramics started to replace traditional materials still used in root canal fillings. The promising clinical results achieved during last 20 years by mineral trioxide aggregate (MTA) promoted in root canal treatments other MTA-like innovative endodontic materials, some of them produced by nanotechnology. Though the newcomers claim to have at least the same efficacy as MTA only rigorous long-term clinical studies might confirm the expectations. Probably the most spectacular effect of using bioceramics in endodontics is mirrored in regenerative treatments. However, are still required proper treatment protocols able to optimize the signaling environment of bioactive molecules for achieving the most efficient pulp regeneration. Pivotal is also the balance between clinical and histological outcomes. As compared to conventional materials used in endodontic treatments bioceramic cements are not only biocompatible but also bioactive as they proved to be involved in controlling the tissue healing and pulp regeneration. MTA or MTA-like cements are already the material of choice in regenerative endodontics, conservative vital pulp therapy and periradicular surgery due to their clinical success rate that spectacularly upraised in recent years. Based on in progress technology of fabrication it is expected that the newcomers belonging to bioceramic cements will overcome some potential clinical and histological downsides. MTA-based endodontic sealers are also promising promoters of improved interfacial bond between the filling material and the dentinal walls of root canal as a guarantee against microinfiltration.

Proposal for a Short Patch Test Series of Dental Materials for Patients with Suspected Oral Contact Allergy

The selection of patch test haptens contained in oral rehabilitation materials is not an easy task, therefore baseline series and additional dental series are used for screening and to increase the chance for the detection of patients contact sensitizations. Moreover, the clinical relevance of positive patch tests must be evaluated. We conducted a biomedical literature search, covering a period of thirty years, using the keywords: contact, allergy, dental, allergens, patch, patients, screening, in order to evaluate many studies including large numbers of patients, tested to various hapten series, in different departments, for the detection of the most common contact allergens involved in dental contact hypersensitivity. We propose a short patch test series of oral rehabilitation materials for patients including six metal haptens present in dental alloys for inlays, crowns, bridges and dentures, one monofunctional methacrylate and one epoxy prepolymer present in dental composite resins, dentin bonding agents and prosthetic materials, one epoxy resin type present in root canal sealants, three odorant constituents contained in provisional restorative and root canal filling materials, periodontal dressings and dental impression materials. Contact allergy to dental haptens is a constant studied subject, but the cost of patch testing with screening and additional or extensive series is relevant, therefore the proposal of a shorter dental material series for patients is aimed to promote sustainability of oral rehabilitation and contact hypersensitivity care and to reduce costs in some real-world settings.

Hyaluronic Acid - Innovative Therapeutic Principle

The article presents the experience of a new therapeutic method, addressing postoperative implant pathology.Methods: Hyaluronic acid has been used in the management of various mucoperiosteal pathologies (directing secondary healing of oral wounds, restoration / increasing the volume of connective tissue – periosteal preoperativ or the papillary volume).Hyaluronic acid used had different concentration. The presentation forms both viscous and fluid particle size and type/acid’s grade of complexation) provided various therapeutic effects with specific indication of administration respected by the authors. Different products available at this time in Romania were used analyzing the results in time.Results: This therapeutic approach provided a good management in secondary granulation and wound healing of oral tissues in difficult cases (GBR, implant therapy) in which the persistence of dehiscence wound can cause a failure of surgical treatment (loss of membrane, alloplastic material or implant).Conclusion: This results places this innovative therapeutic method with others successful therapeutic solutions in usual dental practice, providing a quick and efficient settlement of some difficult clinical cases.

Computational Study of Physicochemical Properties of the Monomers Used in Stomatology

Monomers used in dentistry allow tackling shrinkage problem during polymerization of dental composites.These monomers may cross biomembranes, a phenomenon that can lead to various toxic responses. An important factor that express the lipophilicity of these compounds is the partition coefficient. This parameter allows assessment of the solubility of a monomer to another and, generally, of a material to another.Computational partition coefficients study of water / octanol for a series of monomeric compounds analyzed showed the contribution of chemical structures dependent descriptors of substances on this parameter. The purpose of the assessment of these molecular descriptors is to show their importance in the partition of the substances studied in two phases aqueous and lipid (n-octanol).This allows optimization of the action of compounds activity very useful in finding new monomers used in dental reconstruction.