Laser Doppler Flowmetry Evaluation of the Microcirculation in Dentistry

This chapter presents the most important features of laser Doppler (LD) techniques: LD flowmetry (LDF) and LD imaging (LDI), together with examples of their clinical applications in dentistry. LDF gives a constant estimation of blood flow at a specified point, whereas LDI gives a ‘snapshot’ of perfusion at a given point. These methods are non-invasive laser-based techniques for monitoring gingival and pulpal blood flow and could be used as a diagnostic tool. In paediatric dentistry and odontology, LDF proved to be an atraumatic real-time method used for determining the tooth vitality by monitoring the pulp microcirculation in traumatized teeth, fractured teeth and teeth undergoing different conservative treatments (e.g. bleaching, dental preparation for prosthetic restorations, etc.). In periodontology, recent studies showed the ability of LDF to evaluate the health of gingival tissue in different types of periodontal diseases. By using LDF, it is also possible to evaluate the outcome after different periodontal treatments. The laser Doppler line scanning can be used for recording the gingival healing process after a surgical procedure in the anterior area of the oral cavity

Optical coherence tomography study regarding the enamel structure before and after debonding

Orthodontic treatments imply the use of different types of adhesives and brackets. However, concerns have been raised regarding the effect of these treatments on the structure of the involved teeth. The debonding process is especially regarded as a concern: due to the use of different pliers tensile and pulling forces the develop on the surface of the tooth. The finishing bur is also a concern. Optical Coherence Tomography (OCT), an emerging technology that performs transverse sections of biological systems has been used in order to obtain a more accurate assessment of enamel quality due to its wide applicability and to its non-invasive properties.OCT, analogous to ultrasound imaging(with the difference that it uses light instead of sound), provides cross-sectional images of the tissue structure on the micron scale, in vivo and in real time. Regarding fixed orthodontic treatments, patients are often subjected in the process to a high risk of enamel decalcification and carious processes. Demineralization usually occurs in the area adjacent to the orthodontic bracket location, where bacterial plaque control is difficult. Therefore, in this study we evaluate using OCT the degree of demineralisation produced in the enamel structure, following the removal of the orthodontic bracket. Also, the amount of adhesive remnants after the removal of the adhesive and the finishing of the dental surface with specific instrumentation is evaluated

Progress in Biomedical Optics and Imaging - Proceedings of SPIE: Introduction

The front matter associated with SPIE Proceedings Volume 8925, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing

Complete denture analyzed by optical coherence tomography

The complete dentures are currently made using different technologies. In order to avoid deficiencies of the prostheses made using the classical technique, several alternative systems and procedures were imagined, directly related to the material used and also to the manufacturing technology. Thus, at the present time, there are several injecting systems and technologies on the market, that use chemoplastic materials, which are heat cured (90-100°C), in dry or wet environment, or cold cured (below 60°C). There are also technologies that plasticize a hard cured material by thermoplastic processing (without any chemical changes) and then inject it into a mold. The purpose of this study was to analyze the existence of possible defects in several dental prostheses using a non invasive method, before their insertion in the mouth. Different dental prostheses, fabricated from various materials were investigated using en-face optical coherence tomography. In order to discover the defects, the scanning was made in three planes, obtaining images at different depths, from 0,01 μm to 2 mm. In several of the investigated prostheses we found defects which may cause their fracture. These defects are totally included in the prostheses material and can not be vizualised with other imagistic methods. In conclusion, en-face OCT is an important investigative tool for the dental practice

Biocatalytic Route for the Synthesis of Oligoesters of Hydroxy-Fatty acids and ϵ-Caprolactone

Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-based polymers. Moreover, enzymatic polymerization using lipase catalysts has become an important green alternative to chemical polymerization for the synthesis of polyesters with biomedical applications, as several drawbacks related to the presence of traces of metal catalysts, toxicity and higher temperatures could be avoided. Copolymerization of ϵ-caprolactone (CL) with four hydroxy-fatty acids (HFA) from renewable sources, 10-hydroxystearic acid, 12-hydroxystearic acid, ricinoleic acid, and 16-hydroxyhexadecanoic acid, was carried out using commercially available immobilized lipases from Candida antarctica B, Thermomyces lanuginosus, and Pseudomonas stutzeri, as well as a native lipase. MALDI-TOF-MS and 2D-NMR analysis confirmed the formation of linear/branched and cyclic oligomers with average molecular weight around 1200 and polymerization degree up to 15. The appropriate selection of the biocatalyst and reaction temperature allowed the tailoring of the non-cyclic/cyclic copolymer ratio and increase of the total copolymer content in the reaction product above 80%. The catalytic efficiency of the best performing biocatalyst (Lipozyme TL) is evaluated during four reaction cycles, showing excellent operational stability. The thermal stability of the reaction products is assessed based on TG and DSC analysis. This new synthetic route for biobased oligomers with novel functionalities and properties could have promising biomedical applications.</p

Fixed partial dentures investigated by optical coherent tomography

Fixed partial prostheses as integral ceramics, integral polymers, metal ceramics or metal polymers bridges, are mainly used in the frontal part of the dental arch (especially the integral bridges). They have to satisfy high stress requirements as well as esthetic. The masticatory stress may induce fractures of the bridges. These may be triggered by initial materials defects or by alterations of the technological process. The fractures of these bridges lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of en-face optical coherence tomography (OCT) in detection and analysis of possible fractures in several integral fixed partial dentures. The materials used were represented by several fixed partial prostheses, integral ceramics, integral polymers, metal ceramics and metal polymers bridges. In order to discover the defects, scanning was performed from incisal, vestibular, oral and cervical directions material defects such as fractures and pores were investigated using OCT. In conclusion, en-face OCT has proven as a valuable non invasive method to investigate fixed partial prostheses before their insertion in the oral cavity

Biocatalytic synthesis of δ-gluconolactone and ε-caprolactone copolymers

The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a valuable raw material, particularly for controlled drug delivery and tissue engineering applications. However, the usefulness of such materials is limited by their low hydrophilicity and slow biodegradation rate. In order to improve polycaprolactone properties and functionalities, copolymerization of ε-caprolactone with δ-gluconolactone was investigated. Since enzymatic reactions involving sugars are usually hindered by the low solubility of these compounds in common organic solvents, finding the best reaction medium was a major objective of this research. The optimal copolymerization conditions were set up by using different organic media (solvent and solvents mixtures), as well as solvent free systems that are able to dissolve (completely or partially) sugars, and are nontoxic for enzymes. Native and immobilized lipases by different immobilization techniques from Candida antarctica B and Thermomyces lanuginosus have been used as biocatalyst at 80°C. Although the main copolymer amount was synthesized in DMSO:t-BuOH (20:80) medium, the highest polymerization degrees, up to 16 for the copolymer product, were achieved in solventless conditions. The products, cyclic and linear polyesters, have been characterized by FT-IR and MALDI-TOF MS analysis. The reaction product analysis revealed the formation of cyclic products that could be the major impediment of further increase of the chain length

Comparative Evaluation of Influence of Nd:YAG Laser (1064 nm) and 980 nm Diode Laser on Enamel around Orthodontic Brackets: An In Vitro Study

(1) Background: The prevention of demineralizing lesions at the enamel structure level continues to represent a challenge in daily dental practice. When bacteria influence the pH level, this will decrease below the threshold for remineralization and the dissociation of hydroxyapatite will occur with a high percentage of phosphate and calcium loss. These elements continue to be studied by many authors in order to obtain a working protocol that will lead to their stabilization at the level of the enamel structure, thus preventing the demineralization process. The aim of this study is to evaluate and compare the influence of two types of laser wavelengths on the surface morphology and mineral components of the enamel through an examination with scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). (2) Methods: Thirty permanent human incisors extracted for periodontal reasons from patients aged 25&ndash;40 years old were selected for this study. Metallic brackets (SS Standard 022 Slot, OC Orthodontics, McMinnville, OR, 97128, USA) were bonded onto each tooth. The buccal surface was randomly assigned three sections: Section A&mdash;negative control (no treatment), section B&mdash;treated with 980 nm Gallium&ndash;Aluminum&ndash;Arsenide diode laser (a 300 &micro;m optic fiber was used with 0.8 W output power, energy density of 5.33 J/mm2, in continuous mode, for 30 s, oriented perpendicularly to the enamel surface in contact mode) (KaVo GENTLEray 980 Diode Laser, Kaltenbach &amp; Voigt GmbH, Biberach, Germany), and section C&mdash;treated with Nd:YAG laser (a 300 &micro;m fiber was carried out at a 1 mm distance from the enamel surface with 0.75 W power, 75 mJ pulse energy, pulse repetition rate of 10 Hz, 5 J/mm2 fluency, average exposure time of 30 s, and water cooling assisted) (LIGHTWALKER AT S, M021-5AF/1 S, Fotona d.o.o, Ljubljana, Slovenia). The elements evaluated in this study were calcium (Ca), phosphate (P), oxygen (O), and carbon (C). A one-way analysis of variance, paired t-tests, and independent t-tests were carried out to evaluate the results using the SPSS 19 IBM Statistical package software for Microsoft. (3) Results: The evaluation of the data indicated that both wavelengths produced an increase in Ca wt% (for diode laser the mean of Ca wt% before irradiation was 21.06, while that after treatment reached 28.24; and for Nd:YAG laser, the mean of Ca wt% before irradiation was 21.31, while that after treatment reached 33.88); as well, the 980 nm diode laser decreased P wt% (from 17.20 before irradiation to 16.92 after irradiation) and the Nd:YAG laser increased P wt% (from 17.46 before irradiation to 18.28 after irradiation). These results showed a statistically significant difference at the p &lt; 0.05 level. (4) Conclusions: It can be concluded that the best improvement of enamel chemical composition was obtained with Nd:YAG irradiation