Perioperative antibiotic prophylaxis is critical in reducing the risk of infection in dental implant surgery. Amoxicillin, a commonly prescribed antibiotic, is often used, but optimal dosing regimens remain unclear. This study aims to evaluate the effectiveness of different amoxicillin regimens in preventing postoperative infections following implant surgery. Materials and Methods A randomized controlled trial was conducted with 120 patients undergoing dental implant surgery. Participants were divided into three groups of 40 each: Group A received 2g of amoxicillin 1 hour preoperatively; Group B received 2g of amoxicillin 1 hour preoperatively and 500mg every 8 hours for 7 days postoperatively; Group C received a placebo. The primary outcome measure was the incidence of postoperative infection within 30 days, evaluated by clinical examination and patient-reported symptoms. Results Postoperative infection rates were significantly different across the groups. Group A showed a 5% infection rate, Group B showed a 2% infection rate, and Group C showed a 15% infection rate. Statistical analysis revealed that both Group A and Group B had significantly lower infection rates compared to the placebo group (p < 0.01). Additionally, Group B had a slightly lower infection rate than Group A, but this difference was not statistically significant (p > 0.05). Conclusion The study demonstrates that a single preoperative dose of 2g amoxicillin significantly reduces the risk of postoperative infections in dental implant surgery compared to a placebo. An extended regimen of amoxicillin postoperatively offers a marginal benefit over the single dose. These findings support the use of perioperative antibiotic prophylaxis with amoxicillin in dental implant surgery.