Purpose: Tooth bleaching has been reported to have side effects on the morphology of enamel, such as change of enamel crystal structure and decalcification at the microscopic level. Previous studies using swept-source optical coherence tomography (SS-OCT) demonstrated that demineralized enamel resulted in an exponential decline of backscatter signal with depth due to the increased porosity of the tissue. Since the signal intensity and attenuation patterns of SS-OCT images are influenced by demineralization, attempts were made to utilize the signal intensity and attenuation coefficient as quantitative parameters for the detection of demineralization. In this study, we assessed the influence of bleaching on the enamel surface using optical parameters obtained from the SS-OCT signal.

 Methods: Ten human anterior teeth were collected and their enamel surfaces were bleached 27 times using SHOFU Hi-Lite. SS-OCT scanning was performed on bleached and non-bleached enamel surfaces. SS-OCT signal analysis was performed using Image J software. The area of interest of 1,000 nm in width and 400 nm in optical depth was then selected from the SS-OCT image for the enamel surface. The integrated value of signal intensity (AUC400) and attenuation coefficient (μ_t) were calculated and statistically analyzed at the significance level of p=0.05.

 Results: μ_t showed significant attenuation of the SS-OCT signal for the bleached enamel (mean±SD; non-bleached enamel: 0.59±0.19, bleached enamel: 0.87±0.23). From the results of AUC400, the bleached enamel also showed significantly higher scattering of the SS-OCT signal than the non-bleached enamel (mean±SD; non-bleached enamel: 96.66±9.26, bleached enamel: 102.93±7.16). However, four enamel surfaces out of the 10 samples showed no significant change of AUC400 or μ_t even after 27 times of bleaching.

 Conclusion: It is suggested that the effect of tooth bleaching on the optical properties of enamel may vary depending on the individual’s tooth characteristics and response.

 Purpose: To investigate the influence of phosphoric acid etching on the dentin-enamel junction (DEJ) using swept-source optical coherence tomography (SS-OCT) and a scanning electron microscope (SEM).

 Methods: Caries-free human third molars were sectioned into halves and polished flat with 600-grit silicon carbide paper under running water. Then, specimens were assigned to four experimental groups: 1) Control without tooth surface treatment (CT group), 2) Primer of Clearfil SE Bond2 (Kuraray Noritake Dental) was applied for 20 seconds, then the tooth surface was dried with air for 5 seconds (SE group), 3) Enamel conditioner (Shofu) was applied for 15 seconds, then the tooth surface was washed with water for 10 seconds and dried with air for 5 seconds (EC group), and 4) K-etchant syringe (Kuraray Noritake Dental) was applied for 15 seconds, then the tooth surface was washed with water for 10 seconds and dried with air for 5 seconds (KE group). After each tooth surface treatment, the specimens were observed using a confocal laser scanning microscope (CLSM) and SS-OCT (Santec Corporation). Then, the specimens were dried, gold-coated, and observed using a SEM.

 Results: CLSM observation showed no crack formation on the tooth surface in any of the groups. On the other hand, SS-OCT observation revealed a white line in the KE group whose brightness increased by about 0.5 mm along the DEJ from the treated tooth surface. Moreover, this white line was not observed in the other groups. In SEM observation, a smear layer was observed in the CT group. On the other hand, enamel and dentin were observed clearly in the SE group, EC group, and KE group, and dentin tubule structures were observed in the dentin area. Furthermore, in the KE group, enamel rod structures were observed in the enamel area.

 Conclusion: Phosphoric acid etching may cause excessive decalcification, making the DEJ more fragile. This vulnerability was also observed by SS-OCT as a white line whose brightness increased along the dentin-enamel junction.

 Purpose: Endodontic-periodontal lesions are usually given root canal treatments rather than periodontal treatments, because root canal treatments are thought to be more effective. However, when apical periodontitis is accompanied by chronic pericoronitis and bone loss around the wisdom tooth behind it, the first choice of treatment procedure is less clear. But even in this case, we obtained highly successful results from treatment based on performing the root canal treatment first, and then dealing with the apical periodontitis below and behind it by extracting the wisdom tooth.

 Case: The patient was a 36-year-old woman who was six months pregnant. She came to the hospital in order to receive treatment for gingival swelling of the left mandibular molar. She had a history of partial restoration by means of a metal inlay about 10 years ago, and had had no discomfort since that treatment. But since about six months ago, she had begun to feel some gingival swelling on the #37 distal side. Based on periodontal examinations and local deep probing around #37, she was found to have tooth mobility of Grade 2. In addition, the crown of the mandibular left third molar (#38) was partially exposed in the oral cavity, and gingival swelling and redness appeared in the mucosa around the area of #38. Dental X-ray showed periapical radiolucency at the apex of #37 to be approximately of crown size, and a half-moon shape radiolucency that extended along the horizontally impacted tooth #38 to just below the mesial contact area. Based on the intra-oral examinations and diagnostic tests, #37 was suspected to have been non-vital. Therefore, we judged from pre-treatment diagnosis that there was chronic apical periodontitis of #37 and chronic pericoronitis of #38. Root canal treatment of tooth #37 was performed first, then root canal filling by lateral condensation and core build-up was performed, thereby removing the former discomfort and clinical condition. Subsequently, tooth #38 was extracted, and #37 was immediately restored with a temporary crown, observed, and finally restored with a full coverage crown prosthodontic. Clinical examination at around one year after all the treatments revealed that the condition was quite normal.

 Conclusion: In a case of apical periodontitis with the complication of chronic pericoronitis, we consider that root canal treatment first is most effective, and can lead to healing regardless of periapical lesion size.

 Objective: A case in which a good result was obtained for a patient with generalized chronic periodontitis (Stage Ⅲ Grade A) using delayed autotransplantation and multiple periodontal surgeries is presented.

 Case: A 65-year-old woman presented with the chief complaint of tooth mobility. The rates of probing depth of 4-5 mm and ≥6 mm were 18.5% and 18.5%, respectively. The rate of bleeding on probing was 24.1%. The plaque control record was 33.3%. The periodontal inflamed surface area was 886.6 mm². Several teeth had displacement and premature contact/occlusal interference. Pus discharge and tooth mobility (Miller’s mobility index: Ⅲ) were observed at 37/47. Grade Ⅱ furcation involvement of the lingual side was recorded in 36. Dental radiographic images disclosed the presence of severe bone defects of 37/47 and a vertical bone defect in 36. Cone-beam computed tomography images showed a 3-wall bone defect in 27 and a 2-wall bone defect with grade Ⅱ furcation involvement of the lingual side in 36. There were tori in the buccal and labial sides. After the initial periodontal therapy and delayed autotransplantation (from 38 to 37), multiple periodontal surgeries (flap operation with osteotomy at 16/17, flap operation between 26 and 27, guided tissue regeneration (GTR) at 27, and GTR with bone swaging technique and free gingival graft at 36) were performed for the areas with probing depth ≥4 mm. After the periodontal surgeries, supportive periodontal therapy was performed every 3 months. The delayed autotransplantation of the tooth and the periodontal tissue showed a good course 7 years after the first visit.

 Conclusion: Delayed autotransplantation and multiple periodontal surgeries led to a good clinical outcome.