Periodontal disease remains a widespread challenge for oral healthcare providers. Its onset and progression are intricately linked to oral hygiene, a modifiable lifestyle factor that significantly impacts both oral and overall health. Neglecting oral hygiene leads to dental plaque accumulation, which can initiate gingivitis within a few weeks. Gingivitis is reversible if addressed promptly; however, if left unchecked, it may progress to periodontitis, resulting in tooth loss and increasing the risk for systemic conditions such as diabetes and adverse pregnancy outcomes. This chapter discusses various aspects of poor oral hygiene and its impact on periodontal health.