Background: In conjunction with post placement in root-filled teeth with periapical healthy conditions, root canal retreatment may be performed to improve the seal of the root canal. Whether root canal retreatment for technical reasons (retreatments in teeth without apical periodontitis (AP)) results in lower frequency of AP is unknown.

Objective: To examine whether there is a difference in frequency of AP between roots with root canals retreated for technical reasons, and roots with root canals not retreated before post placement, with a minimum follow-up of 5 years. Also, to examine changes in root filling quality following root canal retreatment for technical reasons.

Methods: This retrospective study included radiographs of 441 root-filled roots without periapical radiolucencies at baseline, scheduled for post and core treatment. Follow-up data for a minimum of 5 years were available for 305 roots (loss to follow-up 30.8%), 46 of which were retreated for technical reasons. Two calibrated observers assessed root filling sealing quality and length, respectively, and periapical status according to the Periapical Index. The main outcome of the study, AP, was used as the dependent variable and all analyses were performed at root level.

Results: The overall frequency of AP at follow-up was 13.8%. The difference in frequency of AP between retreated (4.3%) and nonretreated (15.4%) root canals was not statistically significant, p = .061. Analyses including only roots with preoperatively inadequate root filling quality showed a statistically significant difference (p = .017) between the two treatment groups (2.4% vs. 22.9%).

Conclusions: Root canal retreatment for technical reasons before post and core placement significantly reduces the frequency of AP in roots with inadequate root filling quality.

It is common knowledge for all dental personnel that root filled teeth can be painful. Earlier studies on this subject are meta-analyses and clinical studies reporting data in relation to the time since treatment was performed, not epidemiological studies reporting on the general population or cohorts who regularly attend dentistry. The studies often report ´all-cause tooth pain´ or´odontogenic´ versus ´non-odontogenic´ tooth pain. These are broad categories with different possibilities for the origins of pain. A better understanding of the possible origins of pain would aid in clinical assessment.

This doctoral thesis is centred around a cross-sectional clinical data collection in general dental practice and follow up of interventions monitored by collecting data from dental records over six years. The aim is to better understand painful root filled teeth better by exploring anamnestic, clinical, and radiographic characteristics at a regular check-up by the regular dentist.

Study I is an observational cross-sectional study. The aim was to investigate the frequency and characteristics of pain and discomfort, irrespective of origin, in a cohort of adult patients regularly attending the Public Dental Service in Sweden. A further aim was to examine whether there was an association between pain symptoms, clinical status and radiological findings. One out of ten participants experienced pain or discomfort from their root filled teeth; the average pain intensity was low. Lower age, tenderness to percussion and apical palpation were associated with painful teeth. Furthermore, 41.9% of the painful teeth had apical radiolucency.

Study II is a case-control study. Cases were participants with at least one painful root filled tooth, and controls were participants with a root filled tooth without pain. The aim was to compare, in detail, painful root filled teeth with root filledteeth without pain matched on age, sex, jaw- and tooth type, with the additional aim to explore patient- and tooth related factors that may explain the pain. It was more common with tenderness to percussion and apical palpation, as well as swelling, pocket depths greater than 6mm and apical radiolucency for the painful teeth. For 60% of the painful teeth, apical periodontitis was the likely origin of pain, marginal periodontitis and TMD were found to contribute in 30%, and for 10%, no obvious clinical or radiological findings could explain the pain.

In Study III, the painful teeth were subdivided into two groups: those with at least one sign of disease and those with no such signs. The aim was to compare painful root filled teeth with and without signs of inflammatory disease, regarding (i) pain characteristics, (ii) impact of pain and (iii) patient characteristics. No differences could be found except for higher pain intensity and no apical palpation of the teeth without signs of disease. The impact of pain was equally low, and there were no differences in patient characteristics.

In Study IV, all the participants from Study I who could be followed for six years were included, and the interventions were followed by collecting data from the dental records. The aim was to explore longitudinally what happens to root filled teeth in terms of interventions, regardless of time since RCT, during six years. A further aim was to explore how the interventions were associated with variables obtained from a standard clinical examination. Regarding the painful teeth, a third were extracted, another third had 'no event' recorded and, in falling order, the rest were 'scheduled for follow-up', had a 'new restoration' or were 'endodontically re- treated'. In comparison, it was more common with extraction and RCT for painful teeth than 'no event', 'scheduled for follow-up' and new restoration.

In conclusion, the findings indicate that pain from root filled teeth is a relatively common problem. Those with pain generally have a low intensity and minimal impact on everyday life. Apical periodontitis is the most common origin of pain, but a few are difficult to diagnose with the common examination modalities. The clinical presentation of teeth with and without signs of inflammation resemble each other, pointing to possible help from other diagnostic modalities. Even though extraction and RCT are more common interventions for painful teeth, not all painful teeth receive an intervention.

To compare pain characteristics, impact of pain and characteristics of patients withpainful root-filled teeth with and without signs of inflammatory dental disease. Thiscross-sectional study was performed in the Public Dental Health services, RegionÖrebro County, Sweden. Adult patients with ≥1 root-filled tooth identified at theirregular check-up were included and assigned to one of two groups; those with ≥1sign of inflammatory dental disease (DD+) and those without any such sign (DD−).Patients/teeth were compared regarding pain characteristics (intensity, frequency,duration, quality and provoking factors), impact of pain (medication intake, impacton life) and patient characteristics as background factors (general health, other bodilyand orofacial pain). Statistics included descriptive data (frequency tables) and groupcomparisons (Chi-square, Fisher’s Exact and Mann-Whitney U-tests). The DD+ groupincluded 27 participants (30 teeth) and the DD− group 22 participants (23 teeth).On average, pain intensity was mild, the frequency most often recurrent, and theimpact was low. Average pain duration since onset exceeded 2 years in both groups.The only observed between-group differences were average pain intensity; 3.1 (0–10Numerical Rating Scale (NRS)) in DD− group compared to 1.6 for DD+ (p = 0.030),and tenderness to apical palpation; only reported in the DD+ group. The similaritiesin clinical presentation between the two groups underscore the difficulties in correctlydistinguishing between pain of odontogenic and non-odontogenic origin in root-filledteeth with a standard clinical investigation. Additional diagnostic methods need to beinvestigated for their ability to differentiate between tooth pain or discomfort of differentorigins

Aim: To investigate what happens to cross-sectionally identified root-filled teeth over a 6-year period, regardless of the time that elapsed since primary root canal treatment, in a cohort of adult patients regularly attending a Public Dental Service. A secondary aim was to investigate how the cumulative events affecting root-filled teeth over the same time were associated with variables obtained from a baseline examination.

Methodology: Adult patients with ≥1 previously root-filled tooth and regularly attending the Public Dental Service in Örebro County were enrolled for study participation in 2015. General dental practitioners examined all identified root-filled teeth in this cohort at baseline using a standardized protocol and were also responsible for further decision-making and treatments. After six years, information on events of the root-filled teeth was collected from dental records. The highest rating (most invasive treatment) on a 5-point ordinal scale was used in the analyses. Regression analyses with stepwise selection were performed for associations between patient- and tooth-related factors and events.

Results: A total of 445 patients with 1007 root-filled teeth were followed the entire observation time. Twenty (2.0%) of the root-filled teeth had endodontic retreatment and 150 (14.9%) were extracted over six years. Among teeth with periapical radiolucency or pain, the majority did not undergo retreatment or extraction; however, the multivariate analysis demonstrated that retreatment or extraction was associated with baseline recordings of teeth with periapical radiolucency (p < .0001), tenderness to percussion (p < .0001), and poor coronal restoration (p < .0001).

Conclusions: This study corroborates the notion that in general dentistry, root-filled teeth with radiological signs of apical disease often remain untreated over time. Furthermore, it also reveals that root-filled teeth presenting with mild pain do not necessarily receive any intervention. However, teeth with baseline signs of apical periodontitis, pain, or inadequate coronal restoration were more likely to have received intervention during the six-year period.