Retreatment of a C-shaped maxillary second molar: case reports and literature review.

The root canal systems of maxillary second molar (MSM) variations are complicated, especially the prevalence of fused roots and consequent merged and C-shaped canals, which represent a clinical challenge because canal configurations can be irregular and unpredictable. The purpose of this article was to present 2 cases with a C-shaped configuration diagnosed during root canal retreatment and perform a literature review of this MSM anatomy. Case 1 reports that two palatal root canals fused into a C-shaped configuration that finally formed an apical foramen, which was classified as Type D. Case 2 reflects the fusion of the distobuccal canal and palatal canal into a C-shaped configuration and the configuration was Type C, which was first reported in a case report. Nonsurgical retreatments were proposed and conducted. Evaluation at a 24-month recall revealed that the two patients were symptom-free, and radiographic examination revealed normal periapical tissue. This report serves to remind clinicians of the complexities of the root canal system and that possible anatomic variation should always be anticipated when formulating an effective root canal treatment plan. The use of CBCT imaging coupled with an operative dental microscope will be helpful in locating and identifying supernumerary canals when a preoperative periapical radiograph shows signs of a fused-rooted MSM.

Antibacterial activity of chrysophsin-3 against oral pathogens and Streptococcus mutans biofilms.

Dental caries and pulpal diseases are common oral bacterial infectious diseases, the prevention and treatment of these diseases require the control of the causative pathogens, such as Streptococcus mutans (S. mutans) and Enterococcus faecalis. As a cationic antimicrobial peptide, Chrysophsin-3 has broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria which may cause a variety of oral infectious diseases. The present study evaluated the potential of chrysophsin-3 against several oral pathogens and S.mutans biofilms. The cytotoxic activity of chrysophsin-3 against human gingival fibroblasts (HGFs) was investigated for potential oral application. We use minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and time-kill assay to evaluate the killing effect of chrysophsin-3. Then scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM) were used to analyze the change of morphology and membrane of the pathogens, Live/Dead staining and confocal scanning laser microscopy (CSLM) was used to observe S. mutans biofilms. The results indicate that chrysophsin-3 has varying antimicrobial activities against different oral bacteria. Chrysophsin-3 did not cause obvious cytotoxicity in HGFs at concentrations of 32-128 µg/ml for 5 min or 8 µg/ml for 60 min. SEM revealed membranous blebs and pore formation on the bacterial cell surface, and TEM showed loss of the nucleoid and dissolution of the cytoplasmic space. Furthermore, the CSLM images indicate that chrysophsin-3 can reduce the viability of the cells within the biofilms significantly and had a comparatively lethal effect against S. mutans biofilms. Taken together, our finding suggests that chrysophsin-3 has potential clinical application in oral infectious disease, especially in preventing and treating dental caries.

Digital planning workflow for partial maxillectomy using an osteotomy template and immediate rehabilitation of maxillary Brown II defects with prosthesis.

BACKGROUND: There is increasing evidence of benefits for the rehabilitation of Brown II defects with prosthesis in surgery. However, the current literature is sparse for maxillary tumour resection using osteotomy templates. OBJECTIVES: To assess the accuracy of maxillectomy using a custom fabricated osteotomy template and to evaluate the prosthesis for surgical accuracy, appearance and functioning (speech, swallowing and occlusal force). METHODS: Ten patients with Brown II defects caused by tumour resection were treated with precise partial maxillectomy using an osteotomy template. The immediate rehabilitation of the Brown II defect was completed with a prefabricated prosthesis. The post-operative three-dimensional images and the pre-operative virtual images were superimposed, and average deviation and maximum deviation were calculated. Speech intelligibility, swallowing, appearance and University of Washington Quality of Life Questionnaire (UW-QoL) were examined at 1, 3 and 6 months after surgery. Occlusal force was examined post-operatively at 6 months. RESULTS: The maximum deviation between the actual and virtual surgery was 5.12 ± 0.44 mm, with an average of 1.02 ± 0.17 mm. Speech intelligibility, swallowing and UW-QoL improved significantly (P < .05) after wearing the prosthesis. The recovery index of the occlusal force on the affected side was 20.19%-32.28%. The skewed degree of the mouth corner, the difference in the height of the left and right lips, the maximum deviation distance and the change area volume decreased significantly (P < .05). CONCLUSION: The precise rehabilitation of maxillary Brown II defects can be achieved using a prosthesis fabricated with an osteotomy template. The prosthesis restored appearance and functional capabilities (such as speech and occlusal force).