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The aim of this study was to present an optimal diagnostic protocol by comparing and analyzing a conventional examination and the quantitative light-induced fluorescence (QLF) technique. Selected were 297 teeth of 153 patients to take QLF images and bitewing radiographs. Occlusal dental caries, proximal dental caries and cracks were evaluated and scored using QLF, X-ray and/or visual criteria. The sensitivity, specificity, and area under the curve (AUC) of a receiver operating characteristic analysis were calculated. Two fluorescence parameters (|ΔFmax| and ΔRmax) were utilized to evaluate the fluorescence pattern according to the severity of lesions based on QLF or X-ray criteria. QLF showed higher scores for detecting occlusal dental caries and cracks than the conventional method. ΔRmax increased more clearly than ΔFmax did with occlusal dental caries. The |ΔFmax| values of occlusal dental caries, proximal dental caries and cracks showed good AUC levels (0.84, 0.81 and 0.83, respectively). The ΔRmax of occlusal dental caries showed the highest AUC (0.91) and the ΔRmax of proximal dental caries showed a fail level (0.59) compared to bitewing radiographs. The QLF image could visualize and estimate the degree of occlusal dental caries or cracks. Consequently, the QLF technique may be an adjunct tool to conventional methods for the detection of occlusal caries and peripheral cracks.

The early noninvasive detection of crown microleakage is very important for tooth maintenance and preservation. A crown margin in a subgingival position combined with the obscuring effect of a ceramic crown make it difficult to diagnose microleakage using traditional methods such as visual-tactile examinations and radiography. The aim of this study was to determine the effectiveness of quantitative light-induced fluorescence (QLF) technology for diagnosing microleakage in an all-ceramic crown noninvasively. In this study the red fluorescence glow was detected through a crown wall using the Qraycam QLF device (AIOBIO, Seoul, Republic of Korea). No abnormalities were detected by a visual examination, whereas the Qraycam device revealed both strong red fluorescence and fluorescence loss in suspicious lesions, which were confirmed after crown removal. It was possible to determine that the carious lesions inside the crown were related to bacteria-induced microleakage. After performing caries removal and crown reattachment, the red fluorescence glow was no longer detected. QLF examinations made it easy to identify the presence of microleakage in an all-ceramic crown noninvasively based on red fluorescence. These findings indicate that QLF technology can be effectively applied to provide objective evidence for detecting microleakage and diagnosing carious lesions inside an all-ceramic crown noninvasively.

This study investigated the bone growth pattern in surgically created coronal defects with various depths around implants in dogs.Four mongrel dogs were used. All mandibular premolars were extracted under general anesthesia and left to heal for 2 months. After ostectomy, bony defects were prepared in test sites, using a stepped drill with a diameter of 6.3 mm and two depths: 2.5 mm (test sites 1 [T1]) and 5.0 mm (test sites 2 [T2]). In the control sites, the implants were placed after ostectomy without any coronal defects. T1, T2, and control sites were prepared in the right and left sides of the mandible. Six implants, 3.3 mm in diameter and 10 mm in length, were placed in each dog; the implants were submerged completely. Two dogs were sacrificed 8 weeks after surgery, and the other two dogs were sacrificed 12 weeks after surgery. The stability of all implants was measured with a resonance frequency analyzer after placement and after sacrifice. All sites were block-dissected for ground sectioning and histologic examination.After 12 weeks of healing, only T2 were not filled fully with bone. At week 8, the mean bone-to-implant contact (BIC) was 47.7% for control, 43.6% for T1, and 22.2% for T2. At week 12, the control BIC was 56.7% and the 2.5-mm defect had a greater BIC (58.8%). However, in the 5-mm defect, the BIC was 35.1%. At insertion, stability was reduced at sites with a greater defect depth. Similar stability was noted in all specimens after 8 and 12 weeks of healing.Bone healing between an implant and marginal bone was compromised at sites with a deeper defect when the width of the bone defect was 1.5 mm.