This PDF file contains the front matter associated with SPIE Proceedings Volume 7162, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The aim of this study was to determine the ability of Terahertz Pulsed Imaging (TPI) to measure mineral changes in enamel lesions during de/remineralisation studies. A comparison was made between transverse microradiography (TMR) and microhardness measurements. Artificial lesions were formed in bovine enamel using a solution of 0.1 M lactic acid (pH 5.0) containing 0.2% Carbopol C907 and 50% saturated with hydroxyapatite. The 20 day experimental protocol consisted of four, one-minute treatment periods with dentifrices containing 10, 675, 1385 and 2700ppm fluoride, a 4 h/day acid challenge, and for the remaining time specimens were stored in a 50:50 pooled human / artificial saliva mixture. Terahertz images were generated by positioning the specimens at the focus of the beam and raster scanning the optics to collect the reflections from the air / enamel (AEI) and lesion / enamel (LEI) interface. Significant differences were observed in the intensity change from baseline of the AEI and LEI reflections upon treatment with the four dentifrices. A linear correlation was observed between ΔAEI vs ΔVHN (r2 = 0.997), ΔAEI vs ΔKHN (r2 =0.964), ΔII (ratio of LEI to AEI) vs ΔΔZ (r2 =0.875) and ΔLEI vs ΔΔZ (r2 =0.870). Statistically significant correlations (p<0.05 Pearson correlation coefficient) were also found between the TPI and microhardness / microradiography data. This study has demonstrated that TPI is a useful technology to measure in vitro (and possibly in situ) mineral changes in enamel and is sufficiently sensitive to discriminate between the levels of remineralization produced by the different dentifrices.

Excessive dental wear (pathological attrition and/or abfractions) is a frequent complication in bruxing patients. The parafunction causes heavy occlusal loads. The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-face optical coherence tomography was used for investigating and imaging of several extracted tooth, with a normal morphology, derived from patients with active bruxism and from subjects without parafunction. We found a characteristic pattern of enamel cracks in patients with first degree bruxism and with a normal tooth morphology. We conclude that the en-face optical coherence tomography is a promising non-invasive alternative technique for the early detection of occlusal overload, before it becomes clinically evident as tooth wear.

Optical coherence tomography (OCT) is emerging as a technology that can potentially be used for the detection and monitoring of early dental enamel caries since it can provide high-resolution depth imaging of early lesions. To date, most caries detection optical technologies are well suited for examining caries at facial, lingual, incisal and occlusal surfaces. The approximal surfaces between adjacent teeth are difficult to examine due to lack of visual access and limited space for these new caries detection tools. Using a catheter-style probe developed at the NRC-Industrial Materials Institute, the probe was inserted into the interproximal space to examine the approximal surfaces with OCT imaging at 1310 nm. The probe was rotated continuously and translated axially to generate depth images in a spiral fashion. The probe was used in a mock tooth arch model consisting of extracted human teeth mounted with dental rope wax in their anatomically correct positions. With this ex vivo model, the probe provided images of the approximal surfaces revealing morphological structural details, regions of calculus, and especially regions of early dental caries (white spot lesions). Results were compared with those obtained from OCT imaging of individual samples where the approximal surfaces of extracted teeth are accessible on a lab-bench. Issues regarding access, regions of interest, and factors to be considered in an in vivo setting will be discussed. Future studies are aimed at using the probe in vivo with patient volunteers.

A large depth range is needed if optical coherence tomography (OCT) is to be used to observe multiple teeth simultaneously. A discretely swept optical frequency domain imaging system with a 24-mm depth range was made by using a superstructure-grating distributed Bragg reflector (SSG-DBR) laser as the light source and setting the frequencystep interval to be 3.13 GHz (λ ≈ 0.026 nm). The swept wavelength range was 40 nm centered at 1580 nm, the resolution was 29 μm, and the A-scan rate was 1.3 kHz. Application of the OCT system to a dental phantom was demonstrated.

The concern with the hydrogen penetration towards the pulp can be observed on the literature by the great number of papers published on this topic; Those measurements often uses chemical agents to quantify the concentration of the bleaching agent that cross the enamel and dentin. The objective of this work was the quantification of oxygen free radicals by fluorescence that are located in the interface between enamel and dentin. It was used to accomplish our objectives a Ruthenium probe (FOXY R - Ocean Optics) a 405nm LED, a bovine tooth and a portable diagnostic system (Science and support LAB - LAT - IFSC/USP). The fluorescence of the probe is suppressed in presence of oxygen free radicals in function of time. The obtained results clearly shows that the hydrogen peroxide when not catalyzed should be kept in contact with the tooth for longer periods of time.

This in vitro study evaluated the morphological changes of the root surface and fracture resistance after Treatment of root cracks by CO2 laser and glass ionomer or mineral trioxide aggregates (MTA).

The study demonstrates the possibility of using laser radiation for the ceramic bracket removing. Three laser radiations were examined for this effect and the removing possibility and velocity together with enamel and root damage were investigated. A diode pumped Tm:YAP microchip laser generating a wavelength 1.9 μm, diode pumped Nd:YAG laser with 1.44 μm wavelength, GaAs diode with 0.808 μm were used for the debonding purpose. The measurement of transmission and absorption of the basic element - bracket, adhesive resin, and enamel was also made with the goal to explain the source of the heat and bracket debonding. The explanation of the debonding effect is also presented. From the results it is possible to conclude that continuously running diode pumped microchip Tm:YAP laser having output power 1W can be a good candidate for ceramic bracket debonding procedure.

A Nd:YAG laser-pumped, frequency-doubled Ti:sapphire laser is used for selective ablation of calculus. The laser provides ≤25 mJ at 400 nm (60-ns pulse width, 10-Hz repetition rate). The laser is coupled into an optical multimode fiber coiled around a 4-in.-diam drum to generate a top-hat output intensity profile. With coaxial water cooling, this is ideal for efficient, selective calculus removal. This is in stark contrast with tightly focused Gaussian beams that are energetically inefficient and lead to irreproducible results. Calculus is well ablated at high fluences ≥2J/cm2; stalling occurs below this fluence because of photobleaching. Healthy hard tissue is not removed at fluences ≤3 J/cm2.

Pulsed CO2 lasers show great promise for the rapid and efficient ablation of dental hard tissues. Our objective was to demonstrate that CO2 lasers operated at high repetition rates can be used for the rapid removal of dentin without excessive thermal damage and without compromising adhesion to restorative materials. Human dentin samples (3x3mm2) were rapidly ablated with a pulsed CO2 laser operating at a wavelength of 9.3-µm, pulse repetition rate of 300-Hz and an irradiation intensity of 18-J/cm2. The bond strength to composite was determined by the modified single plane shear test. There were 8 test groups each containing 10 blocks: negative control (non-irradiated non-etched), positive control (non-irradiated acid-etched), and six laser treated groups (three etched and three non-etched sets). The first and second etched and non-etched sets were ablated at a speed of 25 mm/sec and 50 mm/sec with water, respectively. The third set was also ablated at 50 mm/sec without application of water during laser irradiation. Minimal thermal damage was observed on the dentin surfaces for which water cooling was applied. Bond strengths exceeded 20 MPa for laser treated surfaces that were acid-etched after ablation (25-mm/sec: 29.9-MPa, 50-mm/sec: 21.3-MPa). The water-cooled etched laser groups all produced significantly stronger bonds than the negative control (p<0.001) and a lower bond strength than the positive control (p<0.05). These measurements demonstrate that dentin surfaces can be rapidly ablated by a CO2 lasers with minimal peripheral thermal damage. Additional studies are needed to determine if a lower bond strength than the acid-etched control samples is clinically significant where durability of these bonded restoration supersedes high bond strength.

New formularizations, techniques and devices have become the dental whitening most safe and with better results. Although this, the verification of the levels whitening is being continued for visual comparison, that is an empirical, subjective method, subject to errors and dependent of the individual interpretation. Normally the result of the whitening is express for the amplitude of displacement between the initial and the final color, being take like reference the tonalities of a scale of color commanded of darkest for more clearly. Although to be the most used scale , the ordinance of the Vita Classical ® - Vita, according to recommendations of the manufacturer, reveals inadequate for the evaluation of the whitening. From digital images and of algorithm OER (ordinance of the reference scale), especially developed for the ScanWhite ©, the ordinance of the tonalities of the scale Vita Classical® was made. For such, the values of the canals of color R, G, and B of medium part average of the crowns was adopted as reference for evaluation. The images had been taken with the camera Sony Cybershoot DSC F828. The results of the computational ordinance had been compared with the sequence proposal for the manufacturer and with the earned one for the visual evaluation, carried through by 10 volunteers, under standardized conditions of illumination. It statistics analyzes demonstrated significant differences between the ordinances.

Blue light, especially from LED devices, is a tool very frequently used in dental procedures. However, the investigations of its effects on dental enamel are focused primarily on enamel demineralization and fluoride retention. Despite the fact that this spectral region can inhibit enamel demineralization, the consequences of the irradiation on demineralized enamel are not known. For this reason, we evaluated the effects of blue LED on enamel remineralization. Artificial lesions formed in bovine dental enamel samples by immersion in undersaturated acetate buffer were divided into three groups. In the first group (DE), the lesions were not submitted to any treatment. In the second (RE), the lesions were submitted to remineralization. The lesions from the third group (LED+RE) were irradiated with blue LED (455nm, 1.38W/cm², 13.75J/cm² and 10s) before the remineralization. Cross-sectional microhardness was used to assess mineral changes induced by remineralization under pH-cycling. The mineral deposition occurred preferably in the middle portion of the lesions. Specimens from group RE showed higher hardness value than the DE ones. On the other hand, the mean hardness value of the LED+RE samples was not statistically different from the DE samples. Results obtained in the present study show that the blue light is not innocuous for the dental enamel and inhibition of its remineralization can occur.

Objectives: To measure the tooth whitening and the surface and intra-pulpal temperature increase in vitro on extracted upper human incisors after chemical, zoom light and diode laser activated bleaching. Materials and Methods: Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n=10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel. Group II was bleached with high intensity advanced power zoom activation light, for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 watt diode laser for three applications of 30 sec each. Degree of whitening was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and intrapulpal. Results: The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Conclusions: Chemical bleaching produces the same whitening effect as zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than zoom AP light. Diode lasers used to activate bleaching gels are not considered dangerous to the vitality of dental pulps using power settings of 2W.

Nowadays the real contribution of light on the acceleration of the chemical reaction for the dental bleaching is under incredulity, mostly because the real mechanisms of its contribution still are obscure. Objectives: Determine the influence of pigment of three colored bleaching gels in the light distribution and absorption in the teeth, to accomplish that, we have used in this experiment bovine teeth and three colored bleaching gels. It is well Known that the dark molecules absorb light and increase the local temperature upraising the bleaching rate, these molecules are located in the interface between the enamel and dentin. Methods: This study was realized using an argon laser with 455nm with 150mW of intensity and a LED with the same characteristics, three colored gels (green, blue and red) and to realize the capture of the digital images it was used a CCD camera connected to a PC. The images were processed in a mathematical environment (MATHLAB, R12 ®). Results: The obtained results show that the color of the bleaching gel influences significantly the absorption of light in the specific sites of the teeth. Conclusions: This poor absorption can be one of the major factors involved with the incredulity of the light contribution on the process that can be observed in the literature nowadays.

Pemphigus vulgaris (PV) is a potentially fatal autoimmune disease that cause blistering of the skin and oral cavity. It is characterized by disruption of cell-cell adhesion within the suprabasal layers of epithelium, a phenomenon termed acantholysis Patients with PV develop IgG autoantibodies against normal constituents of the intercellular substance of keratinocytes. The mechanisms by which such autoantibodies induce blisters are not clearly understood. The qualitative analysis of such effects provides important clues in the search for a specific diagnosis, and the quantitative analysis of biochemical abnormalities is important in measuring the extent of the disease process, designing therapy and evaluating the efficacy of treatment. Improved diagnostic techniques could permit the recognition of more subtle forms of disease and reveal incipient lesions clinically unapparent, so that progression of potentially severe forms could be reversed with appropriate treatment. In this paper, we report the results of our micro-Raman spectroscopy study on tissue and blood serum samples from ill, recovered and under therapy PV patients. The complexity of the differences among their characteristic Raman spectra has required a specific strategy to obtain reliable information on the illness stage of the patients For this purpose, wavelet techniques and advanced multivariate analysis methods have been developed and applied to the experimental Raman spectra. Promising results have been obtained.

Apatite is expected to be a useful material for artificial bones in surgery and artificial dental roots in dentistry. In particular, studies have recently been conducted into the reconstruction of teeth using Hydroxyapatite (HAp), and several supplements such as gum have become popular for keeping teeth in good condition. However, the decalcifying and calcifying processes are still not well understood. The aim of this research is to study the decalcifying and calcifying mechanisms of HAp. Specifically, the calcifying treatments were carried out on sintered pellets of HAp without pores using Phosphate Acid Maltodextrin (PMD) and Xylitol calcifying promotion agents. A natural calcifying liquid which simulates the situation within a human mouth was used as a reference. SEM, EDX, X-ray, IR and Raman measurements were used for the characterization of structures, morphologies, formed elements and physical properties. It was confirmed that a precursor material OCP was grown on the HAp pellet by the calcification treatment using each promotion agent.

Digital Transverse microradiography (TMR) offers several advantages over film based methods including real-time image acquisition, excellent linearity with exposure, and it does not require expensive specialized film. The purpose of this work was to demonstrate that a high-resolution digital microradiography system can be used to measure the volume percent mineral loss for sound and demineralized enamel and dentin thin sections from 150-350-µm in thickness. A custom fabricated digital microradiography system with ~ 2-µm spatial resolution consisting of a digital x-ray imaging camera, a computerized high-speed motion control system and a high-intensity copper Kα x-ray source was used to determine the volume percent mineral content of sound and demineralized tooth sections. The volume percent mineral loss was compared with cross-sectional microhardness measurements on sound extracted human teeth. The correlation between microhardness and microradiography was excellent (Pr=0.99) for section thickness ranging from 59-319-µm (n=11). The attenuation was linear with varying exposure time from 1-10 seconds. Digital TMR is an effective and rapid method for the assessment of the mineral content of enamel and dentin thin sections.

Several studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to nondestructively measure the severity of subsurface demineralization in enamel and dentin. The reflectivity in the polarization state orthogonal to the initial linear polarization incident on the tissue is low at sound tissues interfaces and high in demineralized areas that strongly scatter and depolarize the light. The purpose of this study was to develop improved algorithms for assessing the depth and severity of demineralization from PS-OCT scans for use with 2D and 3D tomographic images. Subsurface caries-like lesions of increasing depth and severity were produced in adjoining windows on ten bovine enamel samples by exposure to demineralization over periods of 1 to 4 days. Each sample also had a sound window to be used as a control. PS-OCT scans were acquired for each sample and analyzed using various methods to calculate the lesion depth and area. Algorithms were developed and used to automatically detect the lesion depth and area, and calculate the volume for improved assessment of lesion severity. Both fixed-depth and automatic edge-finding algorithms were able to detect significant differences between each of the days and sound enamel. The lesion depth and mineral loss were also measured with polarized light microscopy and transverse microradiography after sectioning the teeth. Mean lesion depths ranged from 40 to 100 µm. This demonstrates the edge-finding algorithm can be used to automatically determine the depth and severity of early lesions for the rapid analysis of PS-OCT images.

Previous studies have demonstrated that Polarization Sensitive Optical Coherence Tomography (PS-OCT) can be used to image the remineralization of early artificial caries lesion on smooth enamel surfaces of human and bovine teeth. However, most new dental decay is found in the pits and fissures of the occlusal surfaces of posterior dentition and it is in these high risk areas where the performance of new caries imaging devices need to be investigated. The purpose of this study was to demonstrate that PS-OCT can be used to measure the subsequent remineralization of artificial lesions produced in the pits and fissures of extracted 3rd molars. A PS-OCT system operating at 1310-nm was used to acquire polarization resolved images of occlusal surfaces exposed to a demineralizing solution at pH-4.5 followed by a fluoride containing remineralizing solution at pH-7.0 containing 2-ppm fluoride. The integrated reflectivity was calculated to a depth of 200-µm in the entire lesion area using an automated image processing algorithm. Although a well-defined surface zone was clearly resolved in only a few of the samples that underwent remineralization, the PS-OCT measurements indicated a significant (p<0.05) reduction in the integrated reflectivity between the severity of the lesions that were exposed to the remineralization solution and those that were not. The lesion depth and mineral loss were also measured with polarized light microscopy and transverse microradiography after sectioning the teeth. These results show that PS-OCT can be used to non-destructively monitor the remineralization potential of anti-caries agents in the important pits and fissures of the occlusal surface.

Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image natural root caries lesions, measure non-destructively the severity of dentin demineralization and determine the efficacy of intervention with anti-caries agents including fluoride and lasers. The objective of this study was to determine if PS-OCT could be used to nondestructively measure the formation of a layer of remineralized dentin on the surface of dentin lesions after exposure to a remineralization solution. In this study images of artificial dentin lesions on extracted human teeth were acquired using PS-OCT after exposure to an artificial demineralizing solution at pH 4.9 for six days and after subsequent exposure to a remineralizing solution at pH 7.0 for 20 days. Polarized light microscopy and microradiography were used to examine histological thin sections from the samples for comparison. PS-OCT successfully measured the formation of a layer of increased mineral content near the lesion surface. PLM and TMR corroborated those results. This study demonstrates the potential use of PS-OCT for the nondestructive measurement of the remineralization of dentin surfaces.

Reflectance and transillumination imaging show demineralization with high contrast in the near-IR. The objective of this study is to use lesion size and contrast acquired in reflectance and transillumination near-infrared imaging modes to estimate the severity of natural occlusal caries lesions. Previous studies have shown that near-infrared (NIR) light can be used to effectively image artificial carious lesions. However, its efficacy on natural lesions requires further exploration. Fifty extracted teeth with varying amounts of occlusal decay were examined using a NIR imaging system operating at 1310-nm. Image analysis software was used to calculate contrast values between sound and carious tooth structure. After imaging, teeth were histologically sampled at 1-mm intervals in order to determine lesion depth. Lesion contrast in transillumination mode significantly increased with lesion depth (p<0.001), while lesion contrast in reflectance mode did not increase. The lesion area demonstrated a significant increase with lesion severity in both imaging modes. These results suggest that lesion contrast and area can be used to estimate lesion severity in NIR images.