Distal displacement of the tooth germ of the mandibular second premolar (MnP2) leads to its impaction and obturation of the eruption path of the mandibular first molar delaying its eruption. The present case report describes the treatment of 2 cases of eruption guidance for distally displaced developing MnP2 that caused delayed eruption of the mandibular first molar. Intentional extraction of primary predecessor results in the mesial shift of the displaced MnP2. However, unfavorable distal ectopic eruption of the mandibular first premolar after the premature loss of primary second molar has been previously reported. Hemisection and sequential extraction of the mandibular primary second molar were performed to mesially shift the distally displaced MnP2, while preventing unfavorable distal ectopic eruption of the mandibular first premolar.

The aim of this study was to evaluate the effects of erythrosine-mediated photodynamic therapy (PDT) on Streptococcus mutans biofilm recovery by counting its colony-forming units (CFUs) and via confocal laser scanning microscopy analysis at different time points following PDT. In PDT, photosensitizer was an erythrosine. S. mutans ATCC25175 biofilms were irradiated using an LED curing light. Chlorhexidine (CHX) was used as positive control. After each antimicrobial treatment, samples were cultured to allow biofilm recovery. Viability was measured by calculating the CFU counts after treatment and after every 3 hours for up to 24 hours. Immediately after treatment, the PDT and CHX groups showed equally significant decreases in S. mutans CFU counts compared to the negative control. After 12 hours of reculture, the PDT group showed no significant difference in the decrease in CFU count compared to the negative control, whereas the CHX group showed significantly lower CFU counts throughout the 24-hour period. Erythrosine-mediated PDT can effectively inhibit S. mutans biofilm formation. However, biofilm recovery occurred earlier in the CHX group after PDT. This study provides insights into the clinical effectiveness of PDT in preventing dental caries.