Objective: Tetracyclines are a unique class of antibiotics which also have additional effects including anti-inflammatory, anti-resorptive and substantive within the root canal. There has been a long-held view that tetracycline medicaments discolour teeth and should be avoided. The evidence base around this topic was explored, including a review of the methodology used in laboratory studies.
Methods: A search of PubMed, Medline and Scopus databases was conducted to identify studies of demeclocycline and doxycycline medicaments used in root canal therapy. An analysis of the methodology used in these studies was performed to determine if these replicate current clinical practice. The related literature on mechanisms of tetracycline stability and the effects of light, oxidation, moisture and chemical interactions was examined. Studies investigating the effects of Ledermix paste on segments of bovine dentine and avulsed or reimplanted teeth as well as combinations with other antibiotics were excluded from this review.
Results: Even though demeclocycline medicament pastes were introduced in 1962, the first laboratory studies of discolouration were not done until 2000. All later studies followed a similar approach, which included exposure to sodium hypochlorite for up to 30 minutes and storage in moist conditions with 100% humidity. Staining during dark storage and enhanced staining on exposure to light were reported, indicating multiple pathways of degradation of demeclocycline and its reaction products.
Conclusion: Light, moisture and oxidation are the key factors which drive discolouration from demeclocycline. Clinical issues from tooth staining can be prevented by removal of medicament pastes from the access cavity, and placement of a sound interim restoration. Use of a doxycycline paste obviates concerns of staining. Laboratory assessments of the potential for staining should replicate in vivo conditions.

Objective: The current pulp diagnostic techniques based on subjective patient response to electrical or thermal stimuli are unable to assess tooth vascularization, which is a true indicator of pulp vitality. The present study evaluates thermography as a pulp vitality test, assessing tooth recovery following thermal stimulation.
Methods: A model simulating intrapulpal circulation was developed. Superficial thermographic measurements were obtained from teeth with and without elevation of the intracoronal temperature before and after applying thermal stress with cold. The data were analyzed using analysis of variance (ANOVA), and the level of significance was set at p<0.05.
Results: The model obtained could help differentiate between teeth with and without simulated pulp circulation. Recovery following application of thermal stress showed significant differences between the two types of teeth.
Conclusion: Thermography has the potential to be used as a diagnostic tool for the vascularity status of the dental pulp.

Objective: The aim of this retrospective clinical study was to evaluate the incidence of ProTaper Universal System instrument fractures, associated with observation of the arch, group of teeth, and root thirds in which these fractures occurred.
Methods: From analysis of charts, clinical record cards and radiographs of endodontic treatments performed by postgraduate students using the ProTaper Universal System at a reference center, a total of 1031 teeth and 2355 canals were analyzed. The general incidence of instrument fractures and their frequency, considering the group of teeth, arch and root thirds, were cataloged and the data obtained were statistically analyzed (Exact Fischer test, with level of significance of 1%).
Results: The general percentage of fractures, considering the number of teeth and number of root canals evaluated was 4.4% and 1.9%, respectively. Instrument fractures occurred more frequently in the mandibular first (8.8%) and second (9.6%) molars, however, without statistically significant difference between them (p=0.81). In the first and second maxillary molars, the incidence of fracture was 4.7% and 5.1%, respectively, also without significant difference (p=0.81). Considering the dental arches (maxillary and mandibular), the fractures occurred with significantly higher frequency in the mandibular arch (66.7%), in comparison with the maxillary arch (33.3%) (p<0.01). A significantly higher percentage of fractures occurred in the apical third (84.4%) compared with the middle third (15.6%) (p<0.01).
Conclusion: The general percentage of fractures, considering the number of teeth and number of root canals evaluated was 4.4% and 1.9%, respectively. However, the arch (mandibular) and root third (apical) had a significant effect on the incidence of instrument fractures.

Objective: Extracellular DNA (eDNA) has been shown to be important for biofilm stability of the endodontic pathogen Enterococcus faecalis. In this study, we hypothesized that treatment with DNase prevents adhesion and disperses young E. faecalis biofilms in 96-well plates and root canals of extracted teeth.
Methods: E. faecalis eDNA in 96-well plates was visualized with TOTO-1®. The effect of DNase treatment was assessed in 96-well plates and in extracted single-rooted premolars (n=37) using a two-phase crossover design. E. faecalis was treated with DNase (50 Kunitz/mL) or heat-inactivated DNase for 1 h during adhesion or after 24 h of biofilm formation. In 96-well plates, adhering cells were quantified using confocal microscopy and digital image analysis. In root canals, the number of adhering cells was determined in dentine samples based on colony forming unit counts. Data from the 96-well plate were analyzed using one-tailed t-tests, and data from extracted teeth were analyzed using mixed-effect Poisson regressions.
Results: eDNA was present in wells colonized by E. faecalis after 1 h of adhesion and 24 h of biofilm formation; it was removed by DNase treatment, as evidenced by TOTO®-1 staining. DNase treatment reduced the area covered by cells in 96-well plates after 1 h (p<0.05), but not after 24 h (p=0.96). No significant differences in the number of adhering cells were observed in extracted teeth after 1 (p=0.14) and 24 h (p=0.98).
Conclusion: DNase treatment does not disperse endodontic E. faecalis biofilms. The sole use of DNase as an anti-biofilm agent in root canal treatments is not recommendable.

Objective: The aim of this in vitro study was to evaluate the genotoxicity and hemocompatibility of a novel calcium aluminate-based cement, EndoBinder (EB) ( Binderware, São Carlos, SP, Brazil) and compare it with Angelus White Mineral Trioxide Aggregate (MTA) (AWMTA) (Angelus, Soluções Odontológicas, Londrina, PR, Brazil).
Methods: For evaluation of genotoxicity, a comet assay was performed with Chinese hamster ovary (CHO) cells that had been grown for 24 h in Dulbecco’s Modified Eagle Medium incubated with each of the cements for 24 h at 37°C. DNA percentage in head and Olive tail moment were analyzed. For assessment of hemocompatibility, erythrocyte lysis quantification, and concentration of plasma fibrinogen were determined in human blood samples placed in contact with each of the materials. One way analysis of variance (ANOVA) followed by post hoc Tukey test and Student t-test were used for data analysis of genotoxicity and hemocompatibility, respectively.
Results: Results showed that the genotoxic effects of EB and AWMTA were comparable to that of the negative control, with no statistically significant differences between AWMTA and negative control (P>0.05). Compared to AWMTA, EB showed greater hemolytic potential when placed in direct contact with erythrocytes (P<0.05). Fibrinogen values were low for both materials, with protein concentration being greater in samples exposed to EB than to AWMTA.
Conclusion: Both materials presented a higher hemolytic behaviour compared to what is established by international standards. Fibrinogen formation was low for both materials, and DNA damage induction was not observed in a comet assay.

Objective: To evaluate the outcome of initial endodontic treatments performed by undergraduate students in a Greek dental school and to determine the factors that may impact the treatment outcome.
Methods: From a randomly selected sample of 677 non-surgical endodontic treatments performed between 2012 and 2015, follow-up appointments were scheduled with patients whose dental records matched the inclusion criteria. After clinical and radiographic examination, the treatment outcome was classified as ‘success’ (healed/healing) or ‘failure’ (uncertain/unsatisfactory healing). The statistical analysis of the data was performed using generalized estimating equations. Intra-examiner and inter-examiner agreements were checked with the intraclass correlation coefficient and with Cohen’s kappa. The statistical significance level was set at p<0.05.
Results: A total of 244 teeth (349 roots) were included for further analysis, and the mean follow-up period was 2.8 years. Overall, the success rate for the treated roots was 72.8%. Μultivariate analysis revealed four decisive factors as having a positive impact on the outcome, namely, the absence of voids within the root fillings (p<0.001), the absence of pre-operative periapical lesions (p=0.001), the extension of the root filling material by 0-2 mm from the radiographic apex (p<0.001) and the root type (anterior roots: p=0.015 and premolar roots: p=0.011). The association of gender, arch, pulp status and type of coronal restoration with the outcome was not statistically significant (p>0.05). Moreover, when the outcome according to pre-operative periapical status and the technical variables of root fillings (apical extension and density) was investigated, roots without periapical lesion, with a root filling material extended 0-2 mm within the apex and without voids revealed the highest success rate (94.5%).
Conclusion: The success rate of non-surgical endodontic treatments performed in a Greek dental school was in the range of those reported in other studies. The pre-operative periapical status, technical variables of root fillings (apical extension and density) and root type were regarded as significant prognostic factors of the outcome.

Objective: To evaluate the radiographic technical quality of root canal fillings performed by senior dental students at Alfarabi colleges for dentistry, Kingdom of Saudi Arabia.
Methods: Radiographic assessment was conducted for 246 teeth (390 root canals) endodontically treated by senior dental students to evaluate the quality of root canal fillings. Three criteria were evaluated to assess the technical quality of root canal fillings: length, density, and taper. The root canal filling was considered acceptable if it had an adequate length with no voids and consistent taper from the orifice to the apex. Statistical analysis was conducted using Kruskal–Wallis, Mann–Whitney, and chi-square tests (P=0.05).
Results: Acceptable root canal fillings were detected in 127 (32.6%) patients. The frequency of an acceptable root canal filling was the highest for the upper anterior teeth (40%). There were significant differences in the length and density among the types of teeth (P<0.05). However, there was no significant difference in the taper among the types of teeth (P>0.05).
Conclusion: The quality of root canal fillings performed by senior undergraduate dental students at AlFarabi colleges for dentistry was acceptable in 32.6% of patients. This outcome enhanced the poor performance of undergraduate dental students in the area of endodontics.

Objective: To investigate apical cracks in roots that exhibit the butterfly effect and that have undergone apical resection and ultrasonic root-end cavity preparation. The effect of the obturation material was also studied.
Methods: Forty extracted single-rooted teeth were decoronated at the cemento-enamel junction. Roots were viewed under a light microscope and coded according to the presence or absence of the butterfly effect. Canals were prepared using ProTaper Next instruments to size X3 and assigned to two obturation groups (gutta-percha and AH Plus, and ProRoot MTA alone). Each contained twenty roots (10 with the butterfly effect and 10 without the butterfly effect). Roots were resected perpendicular to their long axis, 3 mm from the apex, and cavities were cut using ultrasonic retrotips. Resin replicas were used for crack imaging from scanning electron micrographs. Statistical analyses were performed using Stata 13.1 (StataCorp, College Station, TX, USA).
Results: Cracks occurred more frequently in teeth with the butterfly effect (80%), with this difference being significant (P=0.001). Most cracks (73%) ran buccolingually. Teeth obturated with MTA developed fewer cracks compared to those obturated with GP and sealer.
Conclusion: Root-ends with the butterfly effect had a significantly higher number of buccolingual cracks following resection and ultrasonic root-end preparation. This might explain the development of some vertical root fractures, which usually run buccolingually. Canal obturation with MTA may be protective.

Objective: To evaluate the fracture resistance of endodontically treated mandibular premolars restored with glass fiber posts using different luting agents.
Methods: Twenty-four extracted single-rooted mandibular premolars were endodontically treated, and post spaces were prepared to receive fiber posts. They were assigned to three test groups (n=8) according to the type of cement used for the cementation of glass fiber posts: RC group: adhesive resin cement group (etch and rinse), SC group: self-adhesive resin cement group, and GC group: glass ionomer cement group. Teeth in all groups were adhesively restored with a composite resin core material and crowned with Ni-Cr crowns. All specimens were subjected to tangential loading using a universal testing machine until fracture at 30°. Failure loads were recorded, and data were analyzed using one-way ANOVA followed by Tukey’s HSD test (α=.05).
Results: Specimens in the RC group were more resistant (258.3±12.7 N) to fracture than those in the SC (218.7±11.1 N) and GC (165.4±8.9 N) groups (P≤.001). One-way ANOVA indicated that the type of cement had a significant effect on the fracture resistance of endodontically treated lower premolars (P≤.001).
Conclusion: The type of cement that was used to fix glass fiber posts was a determining factor of the fracture resistance of endodontically treated lower premolars.

Objective: Dens evaginatus (DE) is an odontogenic developmental anomaly that can be defined as a supernumerary tubercle structure that extends from the occlusal surface of the affected tooth. Tubercular fracture or attrition of the tubercle, invaded by pulp tissue, may cause various pulpal diseases, such as pulpitis, pulp necrosis, and periapical periodontitis. This study aimed to determine the prevalence of premolars with DE in Taiwanese and Spanish study populations and to report associated dental complications.
Methods: This study was based on the clinical examination of volunteers of Spanish and Taiwanese origin, recruited among the undergraduate dentistry students at CEU-Cardenal Herrera University, Valencia, Spain. Informed consents were obtained from students identified with DE. Additional examinations were performed, including vitality test, percussion, palpation, and radiographs, to diagnosis the status of the pulp and periapical tissue.
Results: The prevalence of DE among Taiwanese students was 4.08%, compared to 0% in the Spanish Caucasian group. In the Taiwanese group, the occurrence of DE in premolars was more common in the mandibular (78.9%) compared to the maxillar region (21.1%). In 84% of the cases, DE-affected teeth were found bilaterally. The mandibular second premolar was the most commonly involved tooth (57.8%). When investigating the complications related to DE among six affected Taiwanese students, it was found that two teeth (10.5%) had received pulp treatment, one of them prior to complete root formation.
Conclusion: DE appears to be more prevalent in people of Mongoloid origin and rare in those of Caucasian origin. The wear or fracture of DE may affect pulpal tissue, leading to incomplete root growth.