Fagpressenytt

Antimicrobial resistance is globally a growing public health threat. Constrained and appropriately targeted use of antibiotics in health care could slow down the development of antibiotic resistance. Dentists are responsible for a substantial proportion of all antibiotic prescriptions, thus it is important that dentists know optimal principles and practices of using antibiotics. In Nordic countries, national guidelines have an important role as a source of up to date knowledge and expert opinion on treatment of dental infections including the use of antibiotics. The Nordic guidelines highlight that antibiotics should be prescribed only with strict indications and the use of broad-spectrum antibiotics should be avoided. At the same time, it should be kept in mind that common, localised dental infections may occasionally develop into severe life-threatening infections. Whenever antibiotic treatment is considered in addition to surgical drainage it should be started an hour before the procedure to avoid spread of the infection when manipulating infected tissues. It is essential that dentists can identify the patients with systemic infection or increased infection risk. Antibiotics are needed in severe infections and for patients with increased risk of infection complications, but primarily, acute dental infections are always treated by efficient drainage and elimination of the infection focus.
Susceptibility of bacterial pathogens to antibiotics has significantly decreased globally over the past two decades. Increasingly many bacteria are also resistant to three or more antibiotics (multidrug resistant strains), all or nearly all current antibiotics (extensively drug resistant strains). WHO has stated that antibiotic resistance is one of the most important public health threats globally. In addition to their activity on targeted pathogens, antibiotics also have an impact on the normal microbiota by creating a selection pressure that favours resistant bacterial strains. Appropriate and constrained use of antibiotics is one of the most important ways of minimising development of drug resistance. (1) The aim of antibiotic stewardship is both to preserve the future effectiveness of antibiotics and to improve patient outcomes. Giving the right drug to the right patient at the right dose at the right time for the right duration via the right route is key in this, and antibiotic guidelines are an important tool for clinical decision-making.
Dentists prescribe a substantial proportion (7-11 %) of all oral antibiotics. Although many of these antibiotic prescriptions may be appropriate and decrease morbidity and mortality to odontogenic infections some are unnecessary or inappropriate (2, 3). Dentists look after patients with increasingly complex medical histories whereby it can be challenging to identify the patients that would need antibiotic therapy. Severely immunocompromised patients can lack typical symptoms of infection because of their deficient immune system and this can make it challenging to diagnose a severe infection. Correct treatment of an acute infection reduces the risk for complicated prolonged infections but will also have the benefit of minimizing the need for antibiotic treatment. The purpose of this review is to give an overview on etiology and diagnosis of local acute dental infections and their recommended treatment principles in outpatient care, and to discuss the current guidelines in the Nordic countries.

Etiology and pathogenesis of acute dental infections
Origins of dental infections
Significant proportion of head and neck infections originate from teeth. Most common sources of dental infections are apical periodontitis, pericoronitis, surgical sites, surgical tooth extraction sites and periodontitis (4,5). The most common route of infection is through the root canal: necrotic pulp becomes infected which leads to the development of apical periodontitis as the immune system is not able to eradicate the microbes in the absence of access to the root canal. The pulp tissue can be infected via various routes: dental caries, tooth fractures, open restoration margins or periodontal disease (6). Acute periodontal infections include periodontal abscess and necrotizing ulcerative gingivitis (NUG) (7). Pericoronitis, local infection of the gingiva and soft tissues adjacent to a partially erupted tooth, is frequently associated with impacted third molars. Most common postoperative complications of surgical tooth extraction are localized surgical site infections and dry socket (8). These mild, localized dental infections may in some cases lead to abscess formation and even to spreading or systemic infections.

Microbiology of dental infections
Purulent dental infections are polymicrobial in nature and usually originate from oral normal microbiota. A typical finding is a mix of strict anaerobic and facultative anaerobic bacteria with anaerobes as dominating species (9). The most common anaerobic isolates in dental abscesses are gram-negative rods, such as Prevotella, Porphyromonas and Fusobacterium species and anaerobic streptococci. Streptococcus anginosus group bacteria among viridans group streptococci are the dominating facultative anaerobic findings. Infrequently also bacterial species considered as transient colonizers (e.g. staphylococci, beta-hemolytic streptococci and enteric rods) may be found in oral infections. These transient colonizers are generally not considered as cause of infection. It is important to remember that in patients with a recent history or hospitalization and broad-spectrumantibiotics, the oral microbiome may have become significantly altered and include various more difficult to treat pathogens (10).

Complications of dental infections
Dental infections may spread locally or hematogenously and develop into severe, life-threatening, disseminated or distant site infections (11, 12). Infection tends to spread towards the lowest tissue resistance, which is dictated by anatomical constraints of the bone, muscle and fascia (figure 1). The most common locations for dental abscess formation are submandibular and sublingual spaces. In some cases, the infection can spread into deep musculofascial spaces and other vital structures such as mediastinum. In addition, locally or hematogenously spreading dental infections may caus