Purpose: Based on the concept of minimal intervention (MI), temporary indirect pulp capping (IPC) is used to preserve the deep parts of dentin adjacent to the pulp and avoid pulp exposure when caries advances deep into the dentin close to the dental pulp. The purpose of this study was to measure the Knoop hardness of softened dentin applied with cured bodies of resin-modified pulp-capping agents containing MTA at 1 month and 3 months postoperatively.

 Methods: We measured the hardness on the side of the enamel of dentin samples with Cariotester, and used those with enamel side hardness of around 60 KNH as healthy dentin samples. We decalcified the healthy samples according to the method of Matsuda et al., and used those whose hardness decreased to around 20 KNH as softened dentin samples. As pulp-capping agents, we applied TMR-MTA cement (TMR) and NEX MTA cement (NEX), which are conventional MTA cements, and TheraCal LC (TCL) and Super MTA Paste (SMP), which are resin-modified pulp-capping agents containing MTA, on softened dentin samples and coated each with base cement to use them as the pulp-capping samples. We measured the Knoop hardness of the softened dentin after storing the prepared pulp-capping samples in a container at 100% humidity for 1 month and 3 months. We prepared three samples for each condition, and subjected the obtained values to statistical analysis using repeated measure analysis of variance and Tukey’s test (p<0.05).

 Results: After application of pulp-capping agents, the Knoop hardness was 32.8±2.7 KNH after 1 month and 33.2±0.4 KNH after 3 months in the TMR group. The hardness values improved significantly after 1 month and 3 months compared to the softened dentin samples, but were significantly lower than those of the healthy samples. In the NEX group, the hardness was 41.1±2.3 KNH after 1 month and 41.6±4.0 KNH after 3 months. The hardness values improved significantly after 1 month and 3 months compared to the softened dentin samples, but were significantly lower than those of the healthy samples. In the TCL group, the hardness was 20.1±0.5 KNH after 1 month and 27.7±4.4 KNH after 3 months. There was no significant difference in hardness after 1 month or 3 months compared to the softened dentin samples, and the values were significantly lower than those of the healthy samples. In the SMP group, the hardness was 56.5±5.9 KNH after 1 month and 62.0±2.5 KNH after 3 months. The hardness improved significantly after 1 month and 3 months compared to the softened dentin samples. Compared to the healthy samples, hardness improved to a level where there was no significant difference both after 1 month and 3 months. The results of this experiment showed that application of resin-modified pulp-capping agents containing MTA on softened dentin induced recalcification and hardened the softened dentin.

 Conclusion: It was concluded that the application of chemical-cured type resin-modified pulp-capping agents containing MTA improved the hardness of the softened dentin to a level that was not significantly different from that of healthy dentin after 1 month and 3 months.

 Purpose: Pit and fissure caries in extracted human premolars were removed by an air abrasive unit with zircon particles, and compared with removal using three types of air abrasive materials (alumina, sodium bicarbonate, and pulverized peach stone).

 Methods: Grinding abilities of the air abrasive materials were investigated by measuring the depth of ground healthy enamel and dentin in the human extracted upper frontal tooth using a three-dimensional electron beam roughness analyzer. For evaluating the removal of premolar pit and fissure caries, DIAGNOdent and a caries detector were used as indices of caries removal, and the colored region or caries region was removed using the air abrasive materials. In addition, the cavity floor was confirmed in samples prepared by grinding the deepest region of the cavity after removal in the buccolingual vertical direction in parallel with the tooth axis using a Vickers hardness tester.

 Results: The depth (μm) of either enamel (mean) or dentin (mean) ground with the air abrasive materials decreased in the order of alumina (132.26, 162.03) >zircon (49.72, 63.09) >sodium bicarbonate (7.81, 10.46) >pulverized peach stone (2.79, 5.50). Healthy dentin ground with either air abrasive material was deeper than ground healthy enamel. In samples ground with alumina and zircon particles, the colored or caries region was entirely removed. When pulverized peach stone or sodium bicarbonate particles were used, the colored or caries region was not entirely removed. Moreover, the cavity floor of healthy dentin was excessively ground with alumina particles, but no excessive grinding with zircon particles was observed.

 Conclusion: Removal of pit and fissure caries in human extracted premolars by an air abrasive unit with zircon particles may also remove enamel, similar to alumina particles, which are capable of completely removing the caries region. In addition, the amount of tooth substance removed was less than when using alumina particles.

 Purpose: Effective mechanical plaque removal is the most important measure for preventing dental caries and maintaining periodontal health. More recently, toothbrush heads with various bristle designs have been developed in an attempt to better reach the interproximal and gingival margin areas. The Bass technique is effective for removing plaque adjacent to and directly beneath the gingival margins with the combined use of a soft toothbrush. The present study evaluated the artificial plaque removal efficacy of a new manual toothbrush with large bristles with highly tapered filaments as compared to small bristles with highly tapered filaments by using a brushing machine.

 Methods: Three different toothbrushes (DENTALPRO black super compact, DENTALPRO black diamond compact, and DENTALPRO black diamond wide) were used in this study. Supra and subgingival access was determined by measuring when brushing using the Bass technique (the toothbrush is positioned in the gingival sulcus at a 45°-angle to the tooth apex and brushed with a force of 200 g at a rate of 190 strokes per 60 s for one minute) on the artificial plaque of a jaw model. The resulting data were analyzed by ANOVA and the Scheffè test (α=0.05).

 Results: No statistically significant differences were founded among the three toothbrushes in terms of artificial plaque removal efficacy in the subgingival facial and subgingival interproximal areas, however, the large brush head bristles provided significantly greater artificial plaque removal efficacy in the supragingival facial and supragingival interproximal areas when compared to the small bristles.

 Conclusions: It is suggested that the highly tapered filaments accessed the subgingival pockets and that the large bristles were more efficient at accessing the supragingival and interproximal regions.

 Purpose: Recently, the number of people receiving a regular dental examination has increased, but the consultation rate among workers remains low. Therefore, we explored the awareness of and health actions for regular dental examinations of tertiary industry workers and discussed awareness-raising activities in future. Furthermore, we clarified the effects of tooth-brushing instruction (TBI) carried out by a dentist at the subject’s workplace.

 Methods: We investigated type of industry, age, sex, whether receiving a regular dental examination or not, reasons in case of not receiving, presence of caries, knowledge of brushing, number of times and duration of brushing, requests about the system of consultation for dental examination, and awareness of the 8020 campaign among workers in tertiary industries using a questionnaire. Logistic regression analyses were performed to evaluate the correlation between regular dental examination (examination group) and the others. In addition, we divided the 21 subjects who did not receive dental examination (non-examination group) into the TBI group (11 subjects) who received oral health instruction and the control group (10 subjects) without instruction. A plaque control record (PCR) was made for all subjects four times every 6 months at each workplace. We compared the PCR value in both groups and discussed the effect of TBI.

 Results: Of the 647 questionnaires which we distributed, 378 were returned (dental examination group: 107, non-examination group: 269, no answer: 2). The main reason for not receiving a dental examination was “no time”. The desired systems for dental examination were “information of recall” in the examination group and “visit dental examination” in the non-examination group. Age, woman, no caries, brushing knowledge, and use of interdental brush or floss were significantly associated with regular dental examination. The PCR value after the second time in the TBI group significantly decreased compared with the first time, and the value after the third time in the control group significantly decreased compared with the first time.

 Conclusion: Receiving regular dental examinations might improve awareness of oral care and acquisition of knowledge about brushing. In addition, it was found that TBI and examinations conducted at the workplace led to a change in behavior toward oral cleaning. These results suggested that an active approach by dentists is important for workers and men under 40 years old.

 Purpose: Intraoral X-ray generates clear images; however, full-mouth X-rays are time-consuming and involve the risk of discomfort to the patient as well as cross-infection by saliva. This study focused on tomosynthesis, in which the shapes and positions of the sections in panoramic X-rays are changed, and images are reconstructed.

 Methods: Panoramic and full-mouth intraoral X-rays were performed using a dental radiography head phantom. Panoramic X-rays involved imaging at five positions, which were the standard positions with displacements of 10 and 20 mm backwards and forwards, followed by correction by tomosynthesis. Taking as the reference a panoramic X-ray from the standard position, a dentist subjectively evaluated each of the following types of images for all 20 subjects: (i) displaced panoramic image; (ii) tomosynthesis-corrected image; and (iii) intraoral image. Evaluation parameters were alveolar crest line continuity, cement-enamel boundary visibility, root canal identifiability, pulp cavity morphology close to the apical region, and alveolar hard line identifiability, in the maxillary anterior dental region and left maxillary molar region. Each of the images was evaluated on a scale of 0 to 4 as follows: 4: very distinct; 3: distinct; 2: visible; 1: partly visible; and 0: completely invisible. In addition, as an objective evaluation, the modulation transfer function (MTF) was analyzed in relation to images at each position and corrected images.

 Results: In the anterior dental region in images displaced 10 mm forwards and the anterior dental and molar regions in images displaced 20 mm forwards, the subjective evaluation was significantly higher with the corrected images (p<0.001). No significant differences were found between the corrected and intraoral images. However, in the anterior dental region in images displaced 10 mm backwards and the anterior dental region and some molar parameters in images displaced 20 mm backwards, the subjective evaluation was significantly higher with the corrected images (p<0.001). Comparison of the corrected images and intraoral X-rays showed that, with backward displacements of both 10 and 20 mm, all parameters other than pulp cavity morphology close to the apical region were significantly higher in the intraoral X-rays (p<0.001). The MTF analysis showed that in the anterior dental region with backward displacement of 10 mm, correction significantly increased the sharpness (p<0.0001).

 Conclusions: Even in images with a large penumbra, from positions with displacement backwards and forwards, significant improvement in sharpness in the anterior dental region was achieved by correction using tomosynthesis. In particular, in the case of imaging with large displacement forwards, correction improved sharpness in both the anterior dental and molar regions, suggesting that images of a quality not inferior to that achieved by intraoral X-rays can be obtained.

 Purpose: To compare the shaping ability of the combination of the R-PILOT (RP) Reciproc glide path file and the conventional Reciproc (RC) or the more flexible Reciproc Blue (RC Blue) by investigating root canal wall displacement on the inner and outer sides of the curvature and the working time.

 Methods: The curvatures of J-shaped curved root canal model blocks were scanned as image files. All canals were negotiated with a #10 stainless steel K-file (KF), randomly divided into six blocks in each of five groups, and prepared to size 25 as follows: group A (#15 KF-#25 KF), group B (RP-R25 RC), group C (#15 KF-R25 RC), group D (RP-R25 RC Blue), and group E (#15 KF-R25 RC Blue). The displacement of the root canal wall on the inner and outer sides of the curvature from the superimposed images before and after preparation and the working time for each group, process, and file were measured. Statistical analysis was performed using the Wilcoxon signed-rank test, one-way analysis of variance, or the Kruskal-Wallis test followed by Dunn’s post hoc test. Values of p<0.05 were considered statistically significant.

 Results: In group A, the root canal wall displacement was the largest on the outer side of the curvature at 1 mm from the apex. In the groups using RP, root canal wall displacement was smaller on the inner side of the curvature at 1 and 2 mm from the apex compared with #15 KF. The groups using RC Blue had less root canal wall displacement on the inner side of the curvature compared with RC, and the displacement on the inner and outer sides of the curvature was almost equal. Total working time was as follows (in decreasing order) : A>E>C>B>D. The working time during glide path preparation was #15 KF>RP, and during root canal shaping was RC>RC Blue.

 Conclusion: The combination of RP and RC Blue maintained the original root canal curvature and shortened the working time.

 Purpose: The purpose of this study was to evaluate the dentin bond strength and elastic modulus of adhesives having polyethylene glycol chains.

 Methods: Flat dentin surfaces were made in non-carious extracted human molars using a diamond saw and 600-grit SiC paper. The surfaces were treated with one of the three one-bottle self-etch adhesives: CFA-2.0 (CFA), iGOS BOND (iGOS), and CLEARFIL S³ BOND ND Quick (NDQ), or a two-step self-etch adhesive; CLEARFIL MEGABOND (MB). The adhesives were applied to the surfaces, and a resin composite was incrementally built on the adhesive. Following 37°C water immersion for 24 h, the specimens were sectioned and subjected to micro-tensile bond strength tests. Four extracted human molars were used to evaluate the elastic moduli of the adhesives. Two mm-thick discs of the coronal dentin were cut and smoothened with 600-grit SiC paper. The four adhesives were applied to the surfaces, then five replicate applications of each adhesive were performed, with irradiation after each application. After 24 h storage in 37°C distilled water, the surfaces of the adhesive layers were assessed using a nanoindenter to determine the elastic modulus. In addition, the primer/adhesive-treated dentin was observed by SEM and the resin-dentin interface was ultra-morphologically characterized by TEM.

 Results: The bond strength of CFA was significantly higher than that of the iGOS and lower than that of MB. There was no significant difference between CFA and NDQ. The elastic modulus of CFA was significantly greater than those of iGOS and NDQ. There was no significant difference between the moduli of CFA and MB. SEM observations of the primer/adhesive-treated dentin confirmed that CFA partially demineralized the dentin surface. TEM revealed that a relatively thin hybrid layer was formed without noticeable demineralization and filler particles were dispersed in the adhesive layer of CFA.

 Conclusion: The bond strength of the adhesive CFA containing a functional monomer having polyethylene glycol chains was equivalent to that of the existing one-step adhesive NDQ containing functional monomer MDP. The bond strength and the elastic modulus were linearly correlated with a high correlation coefficient (0.9899).

 Purpose: The purpose of this study was to evaluate the dentin demineralization and smear layer removal ability of 3% EDTA of pH 12.2 (pH 12.2 EDTA) as a root canal irrigant.

 Method: The demineralization effect of the pH 12.2 EDTA was analyzed using 10 human permanent teeth with a single root canal. The test samples were prepared by inducing a smear layer on the cross section of dentin after vertically cutting the teeth, and 3% EDTA of pH 9.0 was used as a control group. The pH 12.2 EDTA was used to irrigate the test samples for 1 to 60 minutes, and the surface hardness of the root canal dentin at each working time was measured by the indentation hardness test (HIT) and the indentation elastic modulus test (EIT). The effect of removing the smear layer was determined by observing the dentin surface by SEM after the pH 12.2 EDTA was applied for each irrigation time, and the state of the remaining smear layer was determined by the 5-step method according to the method of Hülsmann. Regarding the chemical stability analysis, the pH 12.2 EDTA solution was classified into storage groups at 25°C and 40°C, and the pH changes and changes of EDTA content were analyzed after storage for 6 months.

 Results: No statistically significant differences of dentin demineralization were found by measuring HIT and EIT. The residual smear layer in the test samples was not observed, and there was no significant difference compared with the pH 9.0 EDTA control group. Furthermore, no significant difference was found in change in dentin hardness after irrigation and the removing effect of the smear layer in the coronal, middle and apical of the root canal. Furthermore, no change was observed in color tone or properties for 6 months under the conditions of storage at 25°C and 40°C.

 Conclusion: The pH 12.2 EDTA solution was shown to have excellent smear layer removal effect and chemical stability as a root canal irrigant.

 Purpose: The direct pulp capping procedure is performed when the dental pulp is accidentally exposed. In this case report of pulp exposure caused by fracture, direct pulp capping using MTA and attachment of the tooth fragment was applied and the prognosis was followed-up.

 Case: A 32-year-old female patient presented with the upper right central incisor horizontally fractured in approximately half of the crown, with pulp exposure, mild spontaneous pain and cold-water pain. Chemical treatment of the exposed pulp surface was performed, and MTA was lightly pressed to the exposed pulp. Subsequently, a self-etching primer was used on both the residual dentin and the fragment, and finally they were bonded to each other with flowable composite resin.

 The prognosis after 3 weeks, 3 months and 6 months was good. Long-term follow-up observation of this case is planned.

 Conclusions: An excellent clinical prognosis was obtained with direct pulp capping in traumatic teeth using MTA compressed toward the pulp side, combined with adhesive attachment of the tooth fragment to prevent microleakage. Protection of the pulp and esthetic restoration were achieved simultaneously with this technique.

 Objective: It is difficult to make a diagnosis and treatment plan for clinical cases involving root fracture and endodontic/periodontal diseases because the relationship between clinical symptoms and causes is unclear. This time, we report a case in which comprehensive treatment based on endodontic and periodontal therapy was performed successfully for a patient who had a chief complaint of full-mouth dental therapy.

 Case: A 52-year-old female, with the chief complaint of full-mouth dental treatment at the first visit. After the completion of treatment, she moved to maintenance and hoped for occlusal recovery of the upper-left second molar (27). At the time of occlusal recovery, improvement of extension of 27, root canal treatment for periapical periodontitis, and implant treatment for 37 were required.

 Overview of first-stage treatment: As a basic treatment, the infected root canal was treated after periodontal treatment. For root bifurcation lesions of 36, periodontal regenerative therapy using autologous bone graft and EMD was performed. After the root canal treatment, crown lengthening surgery was performed for 26 in consideration of the final prosthesis, and the crown length extension and clearance were secured. Root fracture was observed in 23 and alveolar bone resorption was progressing, so the tooth was extracted and implant treatment was performed. After periodontal and root canal therapy, occlusal reconstruction treatment was performed on teeth 16-26 and 46-36.

 Overview of second-stage treatment: Since the patient hoped for occlusal recovery during the maintenance period, occlusal reconstruction treatment with infected root canal treatment for 27 and implant treatment for 37 were started. For 27, after performing root canal treatment under an operative microscope, an abutment was built and a crown lengthening operation was performed to secure clearance with a mating implant.

 The progress of infected root canal treatment of 27 was favorable, and the implant for 37 was placed with the superstructure aligned on the occlusal plane. After confirming the health of the upper and lower gingiva, superstructures for 27 and 37 were prepared and occlusal recovery up to 27 was completed. Currently, maintenance is being carried out continuously, and 4 years have passed since the end of treatment, with smooth progress.

 Conclusion: It is considered that the most important and final occlusal construction is smoothly guided by comprehensive basic treatment based on an exact preoperative diagnosis and treatment plan. It is considered that the operative dental microscope enables highly accurate treatment for infected root canals, crown restoration, and prosthodontic treatment, and contributes to the improvement of clinical results.

 Purpose: The pathogenesis of internal root resorption is not fully understood, and trauma and chronic pulpitis are considered to be major risk factors. Usually, this process is asymptomatic and is diagnosed by routine X-rays. This case report describes a very slow progression of internal absorption associated with traumatic injury. Dental cone beam CT (CBCT) results showed that the internal absorber had not been drilled out, so we decided on a non-surgical treatment. The combination of CBCT and microscopy gave a good prognosis.

 Case: The patient was a 40-year-old man with the chief complaint of suspected internal absorption of #11, who was referred for examination by a general dental clinic. The patient had a history of trauma to the maxillary anterior teeth, having fallen from a bicycle about 15 years ago. The patient was less aware of symptoms and had no pain to date. In the buccal periapical tissue of #11, a sinus tract was observed. According to clinical findings and CBCT imaging, the case was diagnosed as apical abscess caused by irregular internal absorption. The treatment strategy was to treat the infected root canal, and after filling the root canal, we selected resin filling as the adhesive repair.

 Conclusion: Since the internal absorption was widespread in the case, it was expected that the roots would become weakened. Moreover, the risk of root fracture was considered to be high. Therefore, the mechanical properties were improved by making the adhesive into a monobloc. The use of CBCT was shown to be extremely effective in the diagnosis and treatment of widespread internal absorption.

 Background: Infection by periodontopathic bacteria and inflammation of periodontal tissue may affect conception. In this case report, we describe a specialized periodontal treatment focusing on removing the source of infection for a patient with aggressive periodontitis during infertility treatment. After the periodontal treatment, the patient had a natural pregnancy and a normal delivery.

 Case: The patient was a 33-year-old married female undergoing infertility treatment. In September 2016, she became aware of looseness of tooth 26 and spontaneous pain, and visited a dental clinic. An X-ray examination indicated that severe alveolar bone resorption was progressing, and she requested specialized periodontal treatment at the University Hospital. There was no special medical history, and there were no abnormal findings in both the patient and her husband on infertility examinations. Periodontal examination revealed that the proportion of periodontal pockets of 4 mm or more was 49.5%, bleeding on probing was 47.9%, plaque control record was 3.1%, and periodontal inflamed surface area (PISA) was 2,392 mm². On X-ray imaging, there were many images showing bone resorption extending to the apex, including tooth 26. Infection by Porphyromonas gingivalis was high in both serum immunoglobulin G antibody titers test and DNA tests for periodontal pathogens in periodontal pockets. The diagnosis was aggressive periodontitis (Stage IV, Grade C) and secondary traumatic occlusion. The treatment policy was to improve the periodontal environment as early as possible (within one year), taking into consideration the patient’s desire for pregnancy. In addition, we explained and obtained consent for the necessity of refraining from pregnancy activities including infertility treatment until periodontal surgery was completed. The treatment plan was: (1) Initial periodontal treatment (patient education, tooth extraction, scaling and root planing with topical antibacterial therapy, temporary fixation), (2) Periodontal tissue regeneration therapy, (3) Oral function recovery treatment, and (4) Supportive periodontal therapy. The host response to periodontal treatment was very good, and improvement of inflammation and regeneration of alveolar bone were confirmed (PISA after periodontal surgery: 43 mm²). She had a spontaneous pregnancy during oral function recovery treatment, and gave birth to a normal boy (3,240 g, birth week: 38 weeks+5 days) at the age of 35.

 Conclusion: It is suggested that severe P. gingivalis infection and periodontal inflammation may affect pregnancy. If the course of infertility treatment is not good, it is desirable to examine the oral condition including periodontal tissue.

 Purpose: A C-shaped root canal has a complex configuration and sources of infection remaining in it make nonsurgical root canal treatment difficult. Here we report a case of endodontic retreatment with good prognosis by using cone-beam computed tomography (CBCT) and a dental operating microscope on a C-shaped mandibular second molar with chronic apical periodontitis.

 Case: A 42-year-old male visited our hospital due to a dull and biting pain in his lower left posterior tooth for approximately one year. The metal inlay on the mandibular left second molar did not fit well and there were percussion pain and occlusal pain at the same tooth. Dental radiography and CBCT of the mandibular left second molar revealed a radiolucent area at the apex, poor root canal filling and separated file-like radiopacity in the root canal. Also, a C-shaped root canal was curved distobuccally at the apex area. Based on the diagnosis of chronic apical periodontitis, the mandibular left second molar was retreated. After removing the infected tissue and shaping the root canal along the C-shape under the microscope, the chief complaint was improved. Root canal obturation was performed and the final restoration with full cast crown was placed 9 months later. At one year after the root canal obturation, the radiolucent area had disappeared and there were no clinical symptoms.

 Discussion and conclusion: It has been reported that the frequency of a C-shaped root canal in the mandibular second molar is higher in Asians than in Caucasians, and that the ratio in Japanese is about 30 to 60%. A C-shaped root canal rarely has the same shape from the orifice to the apex, and there are many branches and confluences, which often cause clinical difficulties. Moreover, compared to the coronal part of the root canal, an undercut exists in the middle and apical part, which often leads to residual infection. In this case, proper access cavity preparation, enlargement of the coronal part of the root canal, and preparation of the middle and apical part were performed under the microscope while referring to the preoperative CBCT images. This process enabled removal of the sources of infection, including residual necrotic pulp-like tissue, and led to good healing.

 Purpose: This report describes comprehensive periodontal therapy, including periodontal regenerative surgery (using REGROTH) for vertical bone defect and the difficulty of reviving the esthetics of the maxillary anterior tooth part and molar tooth part occlusion for generalized severe chronic periodontitis.

 Methods: A 62-year-old woman who visited the Department of Periodontology and Endodontology, Tohoku University Hospital, with the chief complaints of tooth mobility and gingival swelling. She had been diagnosed with breast cancer in 2002, undergone surgery, and received follow-up treatment thereafter, without recurrence. In 2019, she was diagnosed with high blood pressure and prescribed anti-hypertension drugs. Intrabony defects of over 6-mm probing pocket depth (PPD) in the upper anterior teeth and lower right side mandibular canine and first premolar were detected. After the initial periodontal therapy, the PPD was 4-5 mm with bleeding on probing (BOP) in the lower right side mandibular premolars, leading to surgical intervention, incision and debridement of the root surface and bone defects using REGROTH.

 Results: After 3 years, PPD had reduced to 2-3 mm, BOP (−). Radiographically, newly-formed bone was observed in the intrabony defects as well. With supportive periodontal therapies performed every 3 months including implant maintenance, the periodontal tissue was maintained for 4 years.

 Conclusion: Periodontal treatment was successfully performed using REGROTH to treat intrabony defects with filled bone, and the periodontal tissue was maintained for 4 years. The case has been progressing smoothly since SPT treatment.