Background: Few studies have reported the use of toothbrushes as a reliable source of DNA for human or gender identification. The present systematic review with the available information was conducted to answer the focus question “Is a toothbrush a reliable source of DNA for human or gender identification?”. Methods: The keyword combination “Toothbrush” and “DNA” was used to search databases including MEDLINE, Scopus, and Web of Science along with a manual search of reference lists of relevant articles. Duplicates and irrelevant articles were excluded, and the remaining articles were fully read for the final selection of articles. The risk of bias of the included studies was evaluated using the Appraisal tool for Cross-Sectional Studies (AXIS tool). Results: Of the 130 articles obtained, 122 duplicates or irrelevant articles were eliminated. Following the full-text reading of eight articles, five articles were selected based on eligibility criteria. The five studies reported that a toothbrush is a good source of DNA irrespective of the time interval. In a few studies some samples were not sufficient for complete DNA profiling due to factors such as the method of DNA extraction. Conclusion: Although a toothbrush is an excellent source of DNA for human and gender identification, future studies with a larger sample size, appropriate control group, and standardized technique of DNA extraction need to be conducted. Additionally, factors influencing the quantity and quality of DNA in toothbrushes need to be determined with standardized techniques.

Debonding and detachment of artificial teeth from the denture base is frequently encountered in prosthodontic practice. This study aims to assess the effect of modifications in the ridge-lap surface of denture teeth with various combinations of mechanical and chemical surface treatments with hydrofluoric acid on bond strength with the acrylic denture base resin and to identify the failure modes (adhesive, cohesive, or mixed). Seventy acrylic resin teeth samples were randomly divided into seven groups (n = 10): a control group (unmodified) and six treatment groups, in which various combinations of mechanical and chemical surface treatments were performed. Then, these teeth were attached to a heat-cured denture base resin block at 45° angulation. The acrylized test samples were thermocycled, and the compressive bond strength was evaluated using a universal mechanical testing machine. The results suggest that roughening with diamond burs yields the highest bond strength, whereas etching/grooving and air abrasion result in the lowest bond strength. Acid etching complemented air abrasion to improve bond strength, while negative effects were noted with acid etching in other groups. Furthermore, roughening at the neck portion of the acrylic teeth can be used by the manufacturing companies as a standard to provide higher bond strength while maintaining the esthetics of the anterior teeth.