This study evaluated the effect of ProTaper Next (PTN), ProTaper Universal Retreatment (PTR) and hybrid instrumentation (HI) for canal filling removal on the fracture resistance (FR), mode of failure (MoF), and filling removal time.

Ninety-six, mandibular premolars were decoronated and randomly divided into 6 groups (n = 16), as follows: sound (S), untreated canals; prepared teeth (P), canals only prepared to ProTaper Universal finishing instrument (F4); endodontically-treated (ET), prepared and obturated canals using the single-cone technique; and groups PTN, PTR, and HI where filling was removed using PTN, PTR, or HI respectively. FR under vertical loading; MoF and time were assessed. Data were analyzed (Significance level [α] = 0.05).

There was a significant difference in FR among all groups (p < 0.001) (HI < P < PTN < S < ET < PTR). HI showed lower FR than S, ET and PTR, and P showed lower FR than PTR (p < 0.05). For experimental groups, there was a significant difference between every group pair (p < 0.05) No significant difference was found regarding MoF distribution (p > 0.05). HI required the highest filling removal time, while PTR required the least (p < 0.05 between every group pair).

The effect of filling removal on FR may depend on the filling removal technique/system used. PTR could be faster and protect against fracture followed by PTN; HI could adversely affect FR. FR may be associated with filling removal time.

This study aimed to systematically review the pain and flare-up effects of calcium hydroxide (CH) as intracanal medication (ICM) in non-vital mature teeth.

Electronic-databases searching for published and grey literature and manual searching were conducted. Only randomized clinical trials (RCTs) were included comparing CH to other ICMs in non-vital mature teeth. The risk of bias was assessed using the RoB 2.0 Cochrane tool. The main outcomes were pain and flare-up. Qualitative and quantitative analysis, wherever applicable, was performed. The certainty of evidence (CoE) was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Sixteen articles were included in 6 comparisons at different time points for different outcomes. CH reduced pain risk than no ICM within the 1–14-days interval (p < 0.05) and than triple-antibiotic paste within the first day (p < 0.05) and was similar to corticosteroid/antibiotics combination (p > 0.05). Chlorhexidine (CHX) or CH/CHX, however, reduced pain levels than CH alone (p < 0.05). CH showed higher flare-up risk than CHX (p < 0.05). CoE, however, ranged from very low to moderate.

Most comparisons for different outcomes are based on very few studies, mostly low-powered, with an overall low CoE. Thus, the available evidence is considered insufficient to either support or refute CH effectiveness or to recommend one ICM over another. Therefore, further well-designed, larger RCTs are required.

PROSPERO database Identifier: CRD42016041953

This study compared the retention of BioAggregate (BA; Innovative BioCeramix) and mineral trioxide aggregate (MTA; Angelus) as coronal plugs after applying different intracanal medications (ICMs) used in regenerative endodontics.

One-hundred human maxillary central incisors were used. The canals were enlarged to a diameter of 1.7 mm. Specimens were divided into 5 groups (n = 20) according to the ICM used: calcium hydroxide (CH), 2% chlorhexidine (CHX), triple-antibiotic paste (TAP), double-antibiotic paste (DAP), and no ICM (control; CON). After 3 weeks of application, ICMs were removed and BA or MTA were placed as the plug material (n = 10). The push-out bond strength and the mode of failure were assessed. The data were analyzed using 2-way analysis of variance, the Tukey's test, and the χ² test; p values < 0.05 indicated statistical significance.

The type of ICM and the type of plug material significantly affected bond strength (p < 0.01). Regardless of the type of ICM, BA showed a lower bond strength than MTA (p < 0.05). For MTA, CH showed a higher bond strength than CON, TAP and DAP; CHX showed a higher bond strength than DAP (p < 0.01). For BA, CH showed a higher bond strength than DAP (p < 0.05). The mode of failure was predominantly cohesive for BA (p < 0.05).

MTA may show better retention than BA. The mode of bond failure with BA can be predominantly cohesive. BA retention may be less affected by ICM type than MTA retention.