MaxSafe: a mobile-friendly calculator for fractional local anesthetic toxicity and epinephrine dose tracking in dental practice.

Background: Local anesthetic systemic toxicity (LAST) is a preventable complication associated with regional anesthesia. When multiple local anesthetic (LA) agents are administered during dental procedures, calculating the cumulative fractional toxicity is cognitively demanding and error-prone. Studies have demonstrated that up to 87% of dental practitioners cannot correctly calculate the LA doses. The risk is amplified in pediatric patients, where fatal overdoses have been reported from dosing calculation errors. Despite the clinical importance of accurate dosing, no freely available peer-reviewed tool combines cartridge-based input, cumulative fractional toxicity calculations, and epinephrine dose tracking in dental practice. Methods: MaxSafe is a free open-source web application. The tool accepts patient weight, age (less than 1 year through 17 years or adult), and status (with independent cardiac and pregnant toggles). It provides five common dental LA formulations with multiple epinephrine concentration options, and uses dental cartridge counts as the input. It calculates the cumulative fractional toxicity in real-time and independently tracks the epinephrine dose against patient-specific limits. In the pediatric mode, the tool applies the American Academy of Pediatric Dentistry (AAPD) Conservative maximum recommended doses and visually restricts age-inappropriate drugs. Additional features include multi-concentration tracking per drug, advisory warnings for hepatic and renal impairments, and a verification summary panel to mitigate automation bias. The accuracy was validated against 23 manually calculated clinical test scenarios, including adult dosing, pediatric dosing, and alternative epinephrine concentration calculations. Results: The app-calculated values matched the manual calculations exactly across all 23 test scenarios. In pediatric scenarios, the AAPD Conservative maximum recommended doses were substantially more restrictive than the Food and Drug Administration-labeled values; a single cartridge of lidocaine in an 8-kg infant produced 96.6% cumulative LA toxicity, and two cartridges of mepivacaine in an 18-kg child exceeded the safe threshold at 128.8%. Conclusion: MaxSafe is a validated, free, open-source clinical decision-support tool that automates fractional toxicity calculations and epinephrine dose tracking for multi-agent LA administration in both adult and pediatric dental practices. This tool is available as a progressive web application at https://thesorenc.github.io/maxsafe-local-anesthesia/.