This PDF file contains the front matter associated with SPIE Proceedings Volume 11217, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

The aim of this in vitro study was to verify the protective effect of short-pulsed CO2-laser irradiation against erosion of human enamel without and combined with TiF4 and AmF/NaF/SnCl2 applications, respectively. After 5 days, significantly reduced surface loss was observed after applying laser irradiation followed by applications of TiF4 or AmF/NaF/SnCl2 solution compared to Fluoride-application alone. After 10 days, a reduced tissue loss was observed in all groups treated with AmF/NaF/SnCl2 solution. This reduction was significantly higher when the application was combined with laser use (P<0.05). Conclusions: Short-pulsed CO2-9.3μm-laser irradiation followed by additional application of AmF/NaF/SnCl2 solution markedly reduces the progression of dental enamel erosion in-vitro.

[Objective] The objective of this study was to monitor and compare heat generation in 3 different restorative materials using infrared thermography (IRT). [Methodology] Three restorative materials were prepared (n=6); Fuji I (GI; GC), Unifast III (AR; GC) and Protemp 4 (AC; 3M ESPE), in clear crown former. The 3 groups were real-time imaged under thermal imaging camera (FLIR) from the beginning of the application and up to 4 min. [Results] One-Way ANOVA with least significant difference (LSD) showed a statistically significant difference between the tested groups (p < 0.05). The highest temperature was detected as follows: AR > AC > GI. [Conclusion] It is recommended to limit the fabrication of acrylic-based provisional restorations to indirect technique.

The study describes a diode system which activates a home-bleaching agent for discolored teeth. The techniques involve pastes utilizing 16 % hydrogen and carbamide peroxide. Two different laser diodes operating at 445 nm and 1.7 um were used. The exposition power densities used were up to 10 W/cm². For bleaching, stereolithographic models and trays were prepared. Bleaching technique was activated laser irradiation lasting for 100 s, bleaching. After the bleaching process, the enamel surface was with the scanning electron microscope. This process resulted in a 2-3 shade change measurement in one treatment.

Internal adaptation of adhesive restorations affects their longevity. In a clinical setting, the dentists use visual and tactile examination to evaluate marginal adaptation, while radiographs provide somewhat reliable information about adaptation or secondary caries present. For class V restorations located on the vestibular (buccal) surfaces, none of the tools available can provide any information about the internal adaptation or the presence of secondary caries. OCT has been proven to be a useful tool for non-destructive assessment of internal adaptation of adhesive restorations. This paper is evaluating the use of a new high-resolution handheld OCT prototype with a pen-shaped intraoral tip and an imaging depth of 8mm to examine the internal adaptation and the presence of demineralization under resin restorations on the vestibular dentin surface. The Axsun OCT system helped evaluate the internal adaptation of composite restorations, differentiate between healthy and demineralised dentin, adhesive, and restoration layers. OCT provided a unique visualization and characterization of internal structures as well as non-contact assessment of marginal adaptation.

The prerequisite for a successful caries management is the early and precise detection of lesions. We have recently shown that depolarization imaging based on polarization-sensitive optical coherence tomography (PS-OCT) is a promising tool to detect demineralized enamel. To validate this contrast mechanism, we acquired data sets of tooth samples with occlusal caries lesions using PS-OCT and x-ray micro-computed tomography (µCT). Spatial alignment of the PS-OCT and µCT volumes was achieved by creating point clouds from surface segmentations, and subsequent registration. PS-OCT depolarization signals are in good agreement with the µCT results, showing the potential of this approach for caries diagnostics.

New imaging technologies are needed for the clinical assessment of lesions on root surfaces. It is not sufficient to simply detect caries lesions; methods are needed to assess lesion depth, structural composition and activity to determine if chemical intervention has the potential to be effective and if remineralization has occurred. Lesions were monitored using CP-OCT during lesion dehydration to assess the lesion structure and any shrinkage. Thermal imaging at 6-10 μm wavelengths and short wavelength-IR imaging at 1450-1750-nm were used to monitor thermal emission during lesion dehydration to assess lesion activity. Imaging probes were custom fabricated for clinical use. We present the first clinical results of a small feasibility study employing CP-OCT, thermal and SWIR imaging to assess lesion activity in vivo on thirty test subjects with suspected root caries lesions.

The major cellular events in the tissue repair are mitogenesis, migration and metabolism. The proteins responsible for coordination of these events are called “growth factors". Activated platelets at the wound margins release several growth factors, such as PDGF, TFG-β and EGF, etc. The current study was conducted to determine whether there are additional effects of PRP combined Laser therapy. In this study PDL cells were obtained during 3rd molar impaction surgery, these cells were cultured under standard conditions and PDLF were spread on tissue culture plates. Platelet concentrate was obtained after centrifugation and 15ml of platelet concentrate was added to each well. Subconfluent monolayer’s were irradiated with an 904nm GaAs laser operated at a power output of 14mv in a continuous wave mode at energy fluences of 4.02J/cm², frequency 10,000 Hz. Time of exposure was 300 sec per well and number of irradiation were 3. After every laser treatment, the culture was incubated for 24hrs. The proliferation rate was determined by nonradioactive assay containing redox indicator with Alamar Blue Dye after 72 hrs. The numbers of cells were counted under neubar counting chamber after 24, 48 and 72 hrs. The results showed that the treatment of fibroblast with LLLT + PRP revealed a considerably higher proliferation activity than control group. The differences were significantly upto 72 hrs (Mann Whitney U test,p<0.001) A cellular effect of the laser and platelet concentrate is clearly discernible. It was concluded that the use of platelet conc.and laser is an effective modality of regeneration.

Optical coherence tomography (OCT) is a powerful imaging modality capable of detecting subtle abnormalities at histological definition. OCT is extremely useful in the detection of epithelial cancers like oral squamous cell carcinoma. Oral squamous cell carcinomas (OSCC) not only demonstrate architectural loss, but also display strong accumulations of keratin, a major tissue biomolecular scatterrer. Our preliminary observations of A-scan intensity data in a contrasting set of oral precancerous, and cancerous tissues have revealed a striking correlation with degree-of-keratinization and histological differentiation grade. This led us to formulate a study aiming to decipher the ‘high-intensity’ data in A-scan plots of normal, oral precancerous and cancerous human tissues. Our further observations in 600 A-scans (300 malignant and 300 non-malignant) suggested a pertinent link between the high-intensity data occurring in A-scan intensity profile and overall distribution of keratin in OSCC.

Oral cancer was ranked as the fifth most common cancers in both sexes in Taiwan in 2014. For patients diagnosed with the advanced or late stage of oral SCC, the five-year survival rate is reported to be ~ 33% suggesting the importance of the early detection of oral cancer. There have been various studies of investigating the clinical utility of OCT for the early detection of oral precancerous lesions with 1300 nm OCT technology. In this study, we have developed a long-wavelength, multiscale OCT imaging system enabling multiscale imaging of the ex vivo oral precancerous tissue with an increased imaging depth. Objectives with two different magnifications are mounted to a power turret, enabling seamless change of the OCT imaging resolution via the software control. OCT imaging over a variety of oral precancer pathologies will be demonstrated with above OCT system.

Tooth surface with pits and fissures is the most prevalent of carious area for suitability of plaque accumulation. Pit and fissure sealing has been proven be effective in preventing and arresting pit-and-fissure occlusal caries lesions of primary and permanent molars in children and adolescents and can greatly affect smooth surface carious lesion reduction. Clinical decision to seal enamel pits and fissures needs to assess caries risk of the tooth. Surface morphology of pit and fissure, judged by dentist’s subjective experience, together with other factors of socioeconomic status of family, dietary habit, caries history, etc, are comprehensively considered. Due to morphological complexity and diversity of tooth surface, the decision lacks objective morphology-based caries-risk assessment of pit and fissure. In the paper, dental plaque-guided evaluation of pit and fissure caries risk based on 3D morphology analysis of occlusal surface is investigated. The 3D point cloud data of tooth surface are obtained from a commercial 3D intra-oral scanner. Pit-andfissure region can be extracted using region growing. Then skeleton of pit and fissure is determined by L1-medial skeleton method. Section profile of pit-and-fissure can then be obtained for morphological analysis. Bearing area curve (BAC) is introduced to evaluate the morphological distribution and five BAC-based parameters are defined as quantitative indices to describe the characteristic of pit-and-fissure morphology. Dental plaque was quantitatively evaluated by image component ratio of fluorescence image. To obtain dental plaque distribution of 3D pit and fissure region, ICP-based contour registration method was proposed to map fluorescence image on 3D occlusal surface. Nonlinear modeling of plaque distribution and morphological feature was explored using RBF neural network. The reported work reveals that 3D morphological parameters can be used as effective predictors for pit and fissure caries risk evaluation.

Dental caries are common chronic infectious oral diseases affecting most teenagers and adults worldwide. Optical coherence tomography (OCT) has been studied extensively for the detection of early carious lesions. Deep learning techniques are a rapidly emerging new area of biomedical research and have yielded impressive results in diagnosis and prediction in the field of oral radiology. Deep learning models particularly deep convolutional neural networks (CNN) can be employed along with OCT imaging system to more accurately identify early dental caries. In this work, after OCT data acquisition, data augmentation was performed to obtain a large amount of training data in order to effectively learn, where collection of such training data is often expensive and laborious. For the backpropagation process, seven optimization methods, namely Adadelta, AdaGrad, Adam, AdaMax, Nadam, RMSProp, and Stochastic Gradient Descent (SGD) were utilized to improve the accuracy of a CNN classifier for diagnosing dental caries. In this study, 75% of the data were utilized for training and 25% for testing. The diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and receiver operating characteristic (ROC) curve were calculated for detection and diagnostic performance of the deep CNN algorithm. This study highlighted the performance of various optimization methods for deep CNN models with OCT images to detect dental caries.

New imaging methods are needed to assess the activity of caries lesions on tooth surfaces. Recent studies have shown that thermal imaging of lesions on root surfaces during dehydration with air can be used to determine if the lesions are active or arrested. In this study changes in the thermal emission of root caries lesions on extracted teeth during dehydration with air was monitored using an imaging system with a miniature thermal camera and a 3D printed handpiece with an integrated air nozzle suitable for clinical use. This study evaluated the performance of the thermal camera for imaging root caries on extracted teeth prior to it's use for in vivo studies. There was a significant difference in the thermal response of sound and root lesion areas of human teeth under dehydration at constant airflow.

New imaging methods are needed to assess the activity of caries lesions on tooth surfaces. Recent studies have shown that changes in the contrast of lesions during dehydration with air at SWIR wavelengths can be used to determine if lesions are active or arrested. In this study changes in the reflectance of caries lesions during dehydration with air was monitored at 1500-1750-nm on extracted teeth using an imaging system with an InGaAs camera, a light source and a 3D printed handpiece with an integrated air nozzle suitable for clinical use. Lesion structure was also assessed with optical coherence tomography and microCT for comparison. This small preclinical study demonstrated that a 3D printed appliance with integrated air for dehydration can be used to acquire SWIR dehydration curves similar to those acquired previously for benchtop imaging systems.

We developed a clinical probe capable of acquiring simultaneous short wavelength infrared (SWIR) reflectance and occlusal transillumination images of lesions on tooth proximal and occlusal surfaces to reduce the potential of false positives. The dual probe is 3D-printed and the imaging system uses a Ge-enhanced camera and fiber-optic light sources that use SWIR light at 1300-nm for occlusal transillumination and SWIR 1450-nm light for reflectance measurements. The purpose of this study was to test the performance of the probe on extracted teeth prior to commencing clinical studies. The dual probe was used to image extracted teeth with proximal and occlusal lesions. SWIR images of each tooth were compared with micro-CT images to assess performance.

Dental composites are used as restorative materials to replace tooth structure after the removal of caries, shaping, covering teeth for esthetic purposes and as adhesives. Dentists spend more time replacing existing restorations that fail than they do placing new restorations. Tooth colored restorations are difficult to differentiate from the surrounding tooth structure making them challenging to remove completely without incidental removal of healthy tooth structure. Previous studies have demonstrated that CO₂ lasers in conjunction with spectral feedback can be used to selectively remove composite from tooth surfaces. In addition, we assembled a system feasible for clinical use that incorporates a spectral feedback system, scanning system, articulating arm and a clinical handpiece and subsequently evaluated the performance of that system on extracted teeth. The purpose of this study was to test this system in vivo to demonstrate its efficacy relative to dental clinicians. Eight test subjects with premolar teeth scheduled for extraction for orthodontic reasons had bilateral premolars prepared with small occlusal cavity preparations and filled with dental composite. The laser scanning system was used to remove the composite from one of the preparations and a dental handpiece was used to remove the composite from the other. Cross polarization optical coherence tomography was used to measure the volume of the preparation before and after composite placement and removal. There was no significant difference in the loss of enamel and residual composite between the laser and the handpiece. This study demonstrated that a computer controlled spectral guided CO₂ laser scanning system can be used in vivo to selectively remove composite from tooth surfaces.