Helicobacter pylori is known as one of the most common Gram-negative bacteria in the world. Infection takes place via oral-oral, gastro-oral, and faecal-oral routes. The oral-oral route is considered to be the most common route of transmission. The presence of H. pylori in the saliva is considered as a factor inducing periodontal disease and tooth decay, as well as changes such as aphthous ulcers, leucoplakia, and lichen planus. Furthermore, existing bacteria in dental plaques such as Streptococcus mutans and Prevotela intermedia may produce bacteriocins that promote the growth of H. pylori. Recent studies have focused on infection of H. pylori mainly in adults, although infection often occurs in early childhood. As such, more studies concerning the developmental population are needed. Saliva, as an easily available biological material, may soon become an important source in the diagnosis of H. pylori infections, especially in children and adolescents.