Risk score algorithm for treatment of persistent apical periodontitis.

By Yu VS, Khin LW, Hsu CS, Yee R, Messer HH.

Date: 11/2014
Journal: J Dent Res.


•Purpose:  to identify potential predictors and develop a Deterioration Risk Score (DRS) in a cohort of patients with AP that had persisted at least 4 yr and to develop a risk score to differentiate lesions requiring further intervention from lesions likely to be compatible with health.

• N= 228 lesions in 182 patients


Inclusion criteria: primary or secondary (nonsurgical) root canal treatment from 2003 to 2008 , with RG showing the entire lesion before treatment and presenting RL associated a root-filled tooth at least 4 yr after treatment.

•Clinical and periapical radiographic examination provided details of signs and symptoms; PA lesion characteristics including size, border, and location; and type and quality of endodontic treatment and post operative restoration.

•questionnaire collected from patient regarding post-treatment experience of pain and flare-up, as well as the self-reported experience of a swelling or sinus tract.

•2 endodontists independently scored lesion sizes on 4 categories:

(1) <2 mm,

(2) 2-4.9 mm,

(3) 5-9.9 mm &(

4) ≥10 mm

•3 categorical outcomes: (I) improved , (U) unchanged  and (D) deteriorated •To assess risk of deterioration for treatment prescription, a risk score algorithm was constructed

Most highlighted Results: 

1.Most lesions (55.7%) had improved over time, while (14%) remained unchanged, and (30%) had deteriorated.

2.Patient-reported post-treatment pain were significantly more common among U & D lesions.

3.Lesions were mostly asymptomatic at recall (92.1%).

4.A sinus tract was present at recall in only 7% more in D.

5. Lesions >2 mm in diameter and lesions that persisted for longer periods were associated with D lesions.

6.Significant predictors of D, “tooth is painful now” (RR: 3.79), sinus tract present (RR: 4.13), and lesion size (RR: 7.20). The only significant predictor of lesion U was “tooth is painful now” (RR: 3.15).

Clinical significance:  

  • Potential risk factors that were clinically and statistically important for both D lesions and U lesions.
  • This model could help the clinician identify persistent AP at low risk for deterioration that will not require intervention. When validated, this tool could reduce the risk of overtreatment.

-limitations of the DRS in clinical practice: A majority of the persistent AP in the study was associated with dense root filling of adequate extensions so that the DRS cannot be applied to AP with poor technical quality. Pain is a predictor in the DRS, but it is a subjective experience. Clinical judgment is needed to determine the dimensions of a radiographic lesion, and this may influence the performance of the DRS model.