The root canal system has a complex anatomy with not only the main canal but also the isthmus, fins, undercuts, lateral canals and apical ramifications; this makes root canal treatment difficult. The lateral canal is considered to be the secondary root canal that branches from the main canal and runs laterally, opening into the lateral aspect of the root surface. In a radiograph evaluating study after root canal filling, the lateral canal is observed in 3.06% of the cases, especially in the maxillary and mandibular premolar and maxillary incisor, while in a study using micro-CT, the lateral canal is observed in the mandibular first premolar (85%), mandibular first molar (84%), maxillary first premolar (52%) and maxillary second premolar (48%). The lateral canal is observed in a small number of premolars to molars in both the maxillary and mandibular.

 The lateral canal contains pulp tissue and when the pulp becomes infected or necrotic, it becomes a pathway for the formation of lesions on the lateral surface of the root. Therefore, it is necessary to differentiate the lateral canal from root perforation, root fracture, periodontitis, and lateral periodontal cysts. The lateral canal is difficult to prepare mechanically using files and is cleaned as the main canal using chemical irrigations. Although the lateral canal can appear to be filled with root canal filling material on radiographs after root canal filling, it has been reported that necrotic pulp tissue, debris and bacteria were mixed with the gutta-percha in the lateral canal. Therefore, chemical irrigation to remove necrotic pulp tissue and bacteria before root canal filling is particularly important, and ultrasonic irrigation with 17% EDTA for 60 seconds improves the penetration of sealer into the lateral canal. The location of the irrigation tip is important for both ultrasonic and sonic irrigation methods, and the negative pressure irrigation seems to be superior in reaching the working length of the irrigant, but less effective in irrigation of the lateral canal. The vertical condensation technique using thermoplastic gutta-percha is superior to the lateral condensation technique in filling the lateral canal with gutta-percha. However, in the case of the lateral condensation technique, the lateral canal is filled with sealer. Both techniques can obturate with gutta-percha or sealer. For this reason, chemical irrigation before root canal filling is important. In addition, it is suggested that the lateral canal may cause the failure of root canal treatment. Therefore, it is recommended that the lateral canal should be taken into consideration in the diagnosis and examination in retreatment cases.

 Purpose: Excess cement around prosthetic appliances must be removed thoroughly because it can cause periodontitis. However, it is sometimes difficult to confirm removal by visual or palpatory examination under the adjacent gingival margin, and residual cement is occasionally encountered in clinical practice. Therefore, we studied the radiopaque properties of cement for use in the diagnosis of residual cement in clinical practice.

 Materials and Methods: First, ten types of cement were cured in small pieces of 0.2 mm and 0.8 mm thick, and radiographs were taken to compare whether the radiographic appearance of the cements differed depending on the type and thickness of the cement. Next, three types of cement were cured as 0.5 mm pieces and radiographed with three sets of X-ray equipment and imaging plates (IPs) to compare whether differences in the radiographic appearance of the cement were caused by differences in the X-ray equipment. X-ray images obtained from these experiments were measured at NIH Image J. The data obtained were subjected to analysis of variance (ANOVA) and Bonferroni post hoc test. The significance level was set at p<0.05. The results are reported as mean±SD.

 Results: Different types and thicknesses of cement and different imaging conditions produced different radiopaque images. Under the same imaging conditions, GC. Freegenol Temporary Pack was more opaque for 0.2 mm cement thickness, and Hy-bond Temporary Cement Soft was more opaque for 0.8 mm cement thickness. When compared under different imaging conditions, the highest opacity was observed for Hy-bond Temporary Cement Hard when the IP plate was imaged with the size 2 standard type of imaging plate using the SEARCHER 70 X-ray system and developed with the VISTA SCAN.

 Conclusion: Dental cements, especially luting cements that may remain in place for a long time, are difficult to detect because of their low radiopaque quality. However, it has been suggested that clinically residual fine surplus cements can be detected by combining an appropriate radiographic system.

 Purpose: Preservation of pulpal vitality is important in the treatment of deep caries. Mineral trioxide aggregate (MTA) has been applied to vital pulp therapy as a pulp capping material with good sealing properties, antibacterial properties, biocompatibility, and ability to induce the formation of calcified tissue. The most common direct pulp capping procedure with MTA is to place a temporary restoration after the initial curing of the paste-type MTA in the first visit. However, this procedure needs to place the final restoration in the second visit. Furthermore, this procedure has problems such as difficulty of paste-type MTA placement, microleakage from temporary material, and invasion in the second visit. This report describes a direct capping procedure using flowable MTA and composite resin without second treatment.

 Case 1: A 34-year-old male patient was found with deep caries in the left maxillary first molar that was diagnosed with reversible pulpitis. Visible pulp exposure was observed after complete caries removal. The exposed pulp surface was protected from bonding and a composite resin wall was made around the exposed pulp surface. After chemical treatment, the exposed pulp surface was filled with flowable MTA. The composite resin wall was filled by composite resin after silane treatment. After three months, the pulp responded normally and permanent restoration was performed with inlay.

 Case 2: A 22-year-old male patient was found with deep caries in the left maxillary first molar that was diagnosed with reversible pulpitis. Approximately 1 mm pulp exposure was observed. Direct pulp capping was performed applying the same procedure as in case 1. Permanent restoration with composite resin was performed on the same day.

 Case 3: A 28-year-old female patient was found with deep caries in the right mandibular second molar that was diagnosed with reversible pulpitis. Approximately 1 mm pulp exposure and subgingival perforation were observed. Direct pulp capping and repair of perforation were performed applying flowable MTA. Permanent restoration with composite resin was performed on the same day.

 Conclusion: A successful prognosis was obtained in three cases, by applying a direct capping procedure using flowable MTA and composite resin. Flowable MTA improves the complexity of the direct capping procedure using original paste-type MTA, and the well-sealed restoration with composite resin will prevent microleakage and eliminate re-entry treatment. It may improve the success rate of direct pulp capping. However, further clinical research is needed to verify the clinical effectiveness of direct pulp capping using this procedure.

 The treatment of endo-periodontal lesions requires careful consideration because of their complicated clinical condition due to the pathological connection between dental pulp and root canals, and periodontal tissues. By presenting three cases of endo-periodontal lesions with different etiologies, this paper describes appropriate treatments and precautions for each case.

 Case 1: Type Ⅰ endo-periodontal lesion, 45; The patient was a 74-year-old woman. The probing pocket depth (PPD) on the buccal areas of 45 was 8 mm in the midbuccal and mesiobuccal areas and 6 mm in the distobuccal area. Probing of the three areas resulted in bleeding. 45 had grade Ⅱ mobility and did not respond to thermal and electric pulp vital tests. Radiography of 45 showed a large restoration located close to the pulp. The lamina dura had disappeared, and the radiolucency of the area surrounding the tooth root from the root apex to the alveolar crest was increased.

 Case 2: Type Ⅱ endo-periodontal lesion, 44; The patient was a 41-year-old woman. 44 had gingival recession and exposed tooth root with the root groove. The deepest PPD on 44 was 4 mm in the mesiobuccal and distobuccal areas. Probing of the two areas resulted in bleeding. 44 did not respond to thermal and electric pulp vital tests. The level of the alveolar bone crest was one-third, and vertical bone resorption from that site was observed and it reached the root apex. A semicircular radiolucent image was also observed around the apex. Periodontal tissue examination and radiographical examinations showed that she suffered from generalized aggressive periodontitis.

 Case 3: Type Ⅲ endo-periodontal lesions, 47; The patient was a 53-year-old man. The deepest PPD on 47 was 13 mm in the midbuccal area with pus discharge. Probing of the area resulted in bleeding. 47 had grade Ⅱ mobility. X-ray/cone-beam CT (CBCT) images showed a C-shaped root and extensive radiolucency of periodontal tissue from the alveolar bone crest to the apex. Periodontal tissue examination and radiographical examinations showed that he suffered from localized chronic periodontitis.

 Conclusion: Distinguishing the type of endo-periodontal lesions should be comprehensively done based on radiographic findings, PPD, pulp vital response on an affected tooth, and the condition of the periodontal tissue around the tooth and in the upper and lower jaws.