How is the biocompatibilty of dental biomaterials evaluated?

All biomaterials used in dentistry must be evaluated for biocompatibility using screening assays to protect patient health and safety. The purpose of this review is to explain the international biocompatibility guidelines, and to explain the structure of a test program. The test program requires the structured assessment of materials into four phases; general toxicity, local tissue irritation, pre-clinical, and clinical evaluation. Different types of screening assays are available, and it is important to understand the advantages and limitations of the various types of assays that are available, so that they can be selected for appropriateness and interpreted accurately. New scientific advances in terms of the chemical properties of dental materials, tissue engineering, stem cell, genetic transfer, biomaterial, and growth factor therapies are under development. These new therapies create improved opportunities to restore and regenerate oral tissues, but they can also present new hazards to patients. Prior to their clinical use, these new technologies must be proven to be safe, and not hazardous to human health. A structured biocompatibility assessment and advice on the selection of assays are outlined to evaluate these new therapies

The effect of Morinda Citrifolia juice as an endodontic irrigant on smear layer and microhardness of root canal dentin

AbstractPurposeThe purpose of this study was to evaluate the effect of Morinda Citrifolia Juice (MCJ) on smear layer removal and microhardness value of root canal dentin in compared with various endodontic irrigants.Material and methodsEighty-four single-rooted human teeth were prepared to apical size of #35. Since decoronation, samples were divided into seven groups of 12 in each (n=12). Specimens were finally irrigated by either 1: 2.5% NaOCl, 2: 6% MCJ, followed by a final flush of 17% ethylene diaminetetraacetic acid (EDTA), 3: 6% MCJ, 4: 2.5% NaOCl then17% EDTA, 5: MTAD, 6: 2% chlorhexidine (CHX), and 7: saline. After irrigation, all samples were subjected to Vickers microhardness test at 100 and 500-μm depths and then were examined under scanning electron microscopy (SEM) and ImageJ program was used to calculate open dentinal tubules. One way ANOVA and post hoc Tukey tests were used to reveal any significant differences among and between groups respectively.ResultsThe microhardness values at 100μm and 500μm for MTAD were significantly lower than for NaOCl+EDTA and MCJ+EDTA groups (p<0.05). MCJ+EDTA, NaOCl+EDTA, and MTAD protocol significantly removed smear layer in compared with control group (p<0.05), with no significant differences among these three groups.ConclusionsIt was concluded that 6% MCJ followed by a final flush of 17% EDTA can be regarded as an effective solution on smear layer removal without any adverse influence on microhardness property of root canal dentin

Differential Biodegradation Kinetics of Collagen Membranes for Bone Regeneration

Native collagen-based membranes are used to guide bone regeneration; but due to their rapid biodegradation, this treatment is often unpredictable. The purpose of this study was to investigate the biodegradability of natural collagen membranes. Three non-cross-linked resorbable collagen barrier membranes were tested: Derma Fina (porcine dermis), Evolution Standard (equine pericardium) and Duo-Teck (equine lyophilized collagen felt). 10 × 10 mm2 pieces of membranes were submitted to three different degradation procedures: (1) hydrolytic degradation in phosphate buffer solution, (2) enzyme resistance, using a 0.25% porcine trypsin solution, and (3) bacterial (Clostridium histolyticum) collagenase resistance test. Weight measurements were performed with an analytic microbalance. Thickness was measured with a digital caliper. Membranes were analyzed at different time-points, up to 21 d of immersion. A stereomicroscope was used to obtain membranes’ images. ANOVA and Student Newman Keuls were used for mean comparisons (p < 0.05), except when analyzing differences between time-points within the same membrane and solution where pair-wise comparisons were applied (p < 0.001). Derma Fina attained the highest resistance to all degradation challenges. Duo-Teck was the most susceptible membrane to degradation, complete degradation occurred as soon as 8 h. The bacterial collagenase solution performed as the most aggressive test as all membranes presented 100% degradation before 21 d.Ministry of Economy and Competitiveness from Spain MINECO/FEDER MAT2017-85999PEuropean Union (EU) MINECO/FEDER MAT2017-85999PRegional Government of Andalusia Research Fund from Spain A-BIO-157-UGR-1

Advanced zinc-doped adhesives for high performance at the resin-carious dentin interface

The purpose of this study was to evaluate the remineralization ability of an etch-and-rinse Zn-doped resin applied on caries-affected dentin (CAD). CAD surfaces were subjected to: (i) 37% phosphoric acid (PA) or (ii) 0.5M ethylenediaminetetraacetic acid (EDTA). 10wt% ZnO nanoparticles or 2wt% ZnCl2 were added into the adhesive Single Bond (SB), to create the following groups: PA+SB, PA+SB-ZnO, PA+SB-ZnCl2, EDTA+SB, EDTA+SB-ZnO, EDTA+SB-ZnCl2. Bonded interfaces were submitted to mechanical loading or stored during 24h. Remineralization of the bonded interfaces was studied by AFM nano-indentation (hardness and Young׳s modulus), Raman spectroscopy [mapping with principal component analysis (PCA), and hierarchical cluster analysis (HCA)] and Masson׳s trichrome staining technique. Dentin samples treated with PA+SB-ZnO attained the highest values of nano-mechanical properties. Load cycling increased both mineralization and crystallographic maturity at the interface; this effect was specially noticed when using ZnCl2-doped resin in EDTA-treated carious dentin. Crosslinking attained higher frequencies indicating better conformation and organization of collagen in specimens treated with PA+SB-ZnO, after load cycling. Trichrome staining technique depicted a deeper demineralized dentin fringe that became reduced after loading, and it was not observable in EDTA+SB groups. Multivariate analysis confirmed de homogenizing effect of load cycling in the percentage of variances, traces of centroids and distribution of clusters, especially in specimens treated with EDTA+SB-ZnCl2.Project MAT2014-52036-P supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER)

Bond strength of orthodontic brackets using different light and self-curing cements

The purpose of the study was to evaluate the shear bond strength of stainless steel orthodontic brackets directly bonded to extracted human premolar teeth. Fifty teeth were randomly divided into five groups: (1) System One (chemically cured composite resin), (2) Light Bond (light-cured composite resin), (3) Vivaglass Cem (self-curing glass ionomer cement), (4) Fuji Ortho LC (light-cured glass ionomer cement) used after 37% orthophosphoric acid–etching of enamel (5) Fuji Ortho LC without orthophosphoric acid–etching. The brackets were placed on the buccal and lingual surfaces of each tooth, and the specimens were stored in distilled water (24 hours) at 37°C and thermocycled. Teeth were mounted on acrylic block frames, and brackets were debonded using an Instron machine. Shear bond strength values at fracture (Nw) were recorded. ANOVA and Student-Newman-Keuls multiple comparison tests were performed (P < .05). Bonding failure site was recorded by stereomicroscope and analyzed by Chi-square test, selected specimens of each group were observed by scanning electron microscope. System One attained the highest bond strength. Light Bond and Fuji Ortho LC, when using an acid-etching technique, obtained bond strengths that were within the range of estimated bond strength values for successful clinical bonding. Fuji Ortho LC and Vivaglass Cem left an almost clean enamel surface after debracketing.This research project was supported, in part, by grant CICYT/FEDER MAT2001-2843-C02. RED CYTED VIII.J

Zn-containing Adhesives Facilitate Collagen Protection and Remineralization at the Resin-Dentin Interface: A Narrative Review

This is a narrative review of the literature assessing the potential effectiveness of doping dentin polymeric adhesives with zinc compounds in order to improve bonding efficacy, reminer alization and protection against degradation. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI and Web of Science. Through our search, we found literature demonstrating that Zn-doped dentin adhesives promote protection and remineralization of the resin-dentin interfaces. The increased bioactivity has also facilitated dentinal tubules’ occlusion by crystals’ precipitation contributing to improved sealing efficacy of restorations. Loading dentin adhesives with zinc gives rise to an increase of both crystallinity of mineral and crosslinking of collagen. The main role of zinc, in dentin adhesives, is to inhibit collagen proteolysis. We concluded that zinc exerts a protective effect through binding at the collagen-sensitive cleavage sites of matrix metalloproteinases (MMPs), contributing to dentin matrix stabilization. Zinc may not only act as a MMPs inhibitor, but also influence signaling pathways and stimulate metabolic effects in dentin mineralization and remineralization processes. Zn-doped adhesives increase the longevity of dentin bonding through MMPs inhibition. Zn poses a remineralization strategy in demineralized dentin

Avaliação de seis meses de restaurações ART de classe I em uma comunidade de alta experiência de cárie no Brasil

The aim of this study to evaluate the success rate in one-surface ART restorations placed in permanent molars using a glass ionomer cement especially developed for ART in a community with high caries experience; to evaluate the operator influence on its success, post-operative sensitivity and technique acceptance by patients. Prior to placement of the restorations, the Gingival Bleeding Index, Visible Plaque Index, DMFT, dmft indices and treatment needed were assessed. One hundred and fifty five one-surface restorations were placed in permanent molars of school children, according to the WHO ART manual, 1997. After 6 months, the success rate was verified clinically and by slides. At baseline, the mean DMFT was 2.56 (&plusmn;1.08) and the mean dmft, 2.53 (&plusmn;2.33). Operators A and B have placed 102 and 53 ART restorations respectively. The mean time of placement was 16 minutes and 25 seconds to operator A and 14 minutes and 43 seconds to operator B. At 6-month follow up, 152 ART restorations were evaluated and 97.3% were assessed to be successful. Two restorations were excluded from the sample because the ART restorations were replaced by amalgam fillings. Only 4 restorations have failed, in which 2 due to caries, 1 due to fistula presence and the other because the restoration was lost. Four patients reported postoperative sensitivity. At this study period, ART treatment seems to be suitable for its purpose. Further evaluations are necessary to the new glass ionomer cements especially developed for ART technique provided good results at 6-month follow up in a community with high DMFT and dmft indices. The success rate for one-surface cavities in permanent molars was 97.3%, and the studied indices seemed to have no influence in this early evolution period.O objetivo deste estudo foi avaliar o índice de sucesso de restaurações de cavidade de classe I, realizadas em molares permanentes, utilizando-se a técnica do ART e um cimento de ionômero de vidro desenvolvido especialmente para a técnica, em uma comunidade de alto risco à cárie; avaliar a influência do operador no sucesso da técnica e avaliar a sensibilidade pós-operatória e a aceitação da técnica por parte dos pacientes. Antes da realização do tratamento verificou-se o índice de placa visível e o índice de sangramento gengival, CPOD, ceo-d e necessidade de tratamento. Um total de 155 restaurações de uma superfície foram realizadas em molares permanentes de escolares, de acordo com o manual de ART da OMS. Após 6 meses, realizou-se o acompanhamento clínico e por diapositivos. Inicialmente, o CPOD foi de 2,56 ( &plusmn;1,08) e o ceod de 2,53 ( &plusmn;2,33 ). Os operadores A e B realizaram 102 e 53 restaurações de ART respectivamente. O tempo médio para o tratamento foi de 16 minutos e 25 segundos para A e 14 minutos e 43 segundos para B. Aos seis meses. 152 restaurações foram avaliadas e 97,3% consideradas sucesso. Duas restaurações foram excluídas da amostra pois foram substituídas por amálgama. Somente 4 restaurações falharam, duas por recidiva de cárie, 1 por presença de fistula e a última por perda da restauração. Quatro pacientes relataram sensibilidade pós-operatória. O tratamento ART cumpriu seus objetivos no período analisado. Avaliações futuras são necessárias, especialmente para os cimentos de ionômero de vidro de alta viscosidade, devido aos bons resultados nesta comunidade de alto índice de cárie. O índice de sucesso foi de 97,3% e os índices de cárie parecem não influenciar no sucesso do tratamento

Influence of DPSS Laser on Polymerization Shrinkage and Mass Change of Resin Composites

This study evaluated the effectiveness of the diode-pumped solid state (DPSS) laser as a light source for light-curing dental resin composites

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362