Abstract: We included two trials in this review, with 62 participants included in the analyses. Both trials were conducted in university dental schools in the USA and compared the effects of oral penicillin V potassium (penicillin VK) versus a matched placebo when provided in conjunction with a surgical intervention (total or partial pulpectomy) and analgesics to adults with acute apical abscess or symptomatic necrotic tooth. The patients included in these trials had no signs of spreading infection or systemic involvement (fever, malaise). We assessed one study as having a high risk of bias and the other study as having unclear risk of bias. The primary outcome variables reported in both studies were participant-reported pain and swelling (one trial also reported participant-reported percussion pain). One study reported the type and number of analgesics taken by participants. One study recorded the incidence of postoperative endodontic flare-ups (people who returned with symptoms that necessitated further treatment). Adverse effects, as reported in one study, were diarrhoea (one participant, placebo group) and fatigue and reduced energy postoperatively (one participant, antibiotic group). Neither study reported quality of life measurements. Objective 1: systemic antibiotics versus placebo with surgical intervention and analgesics for symptomatic apical periodontitis or acute apical abscess Two studies provided data for the comparison between systemic antibiotics (penicillin VK) and a matched placebo for adults with acute apical abscess or a symptomatic necrotic tooth when provided in conjunction with a surgical intervention. Participants in one study all underwent a total pulpectomy of the affected tooth, while participants in the other study had their tooth treated by either partial or total pulpectomy. Participants in both trials received oral analgesics. There were no statistically significant differences in participant-reported measures of pain or swelling at any of the time points assessed within the review. The MD for pain (short ordinal numerical scale 0 to 3) was -0.03 (95% CI -0.53 to 0.47) at 24 hours; 0.32 (95% CI -0.22 to 0.86) at 48 hours; and 0.08 (95% CI -0.38 to 0.54) at 72 hours. The SMD for swelling was 0.27 (95% CI -0.23 to 0.78) at 24 hours; 0.04 (95% CI -0.47 to 0.55) at 48 hours; and 0.02 (95% CI -0.49 to 0.52) at 72 hours. The body of evidence was assessed as at very low quality. Objective 2: systemic antibiotics without surgical intervention for adults with symptomatic apical periodontitis or acute apical abscess We found no studies that compared the effects of systemic antibiotics with a matched placebo delivered without a surgical intervention for symptomatic apical periodontitis or acute apical abscess in adults. There is very low-quality evidence that is insufficient to determine the effects of systemic antibiotics on adults with symptomatic apical periodontitis or acute apical abscess.

Plain-language summary: The evidence on which this review is based was up-to-date as of 26 February 2018. We searched scientific databases and found two trials, with 62 participants included in the analysis. Both trials were conducted at dental schools in the USA and evaluated the use of oral antibiotics in the reduction of pain and swelling reported by adults after having the first stage of root canal treatment under local anaesthetic. The antibiotic used in both trials was penicillin VK and all participants also received painkillers. Key results The two studies included in the review reported that there were no clear differences in the pain or swelling reported by participants who received oral antibiotics compared with a placebo (a dummy treatment) when provided alongside the first stage of root canal treatment and painkillers. However, the studies were small and produced poor quality evidence, and therefore we cannot be certain if the results are correct. Neither study examined the effect of antibiotics on their own, without surgical dental treatment. One trial reported side effects among participants: one person who received the placebo medication had diarrhoea and one person who received antibiotics experienced tiredness and reduced energy after their treatment. Quality of evidence We judged the quality of evidence to be very low. There is currently insufficient evidence to be able to determine the effects of antibiotics in these conditions.