Evangelos G. Kontakiotis

Long-Term Seal Provided by Some Root-End Filling Materials

A tight and long-lasting seal of root-end fillings is of prime clinical importance. A hundred standard bovine root sections, each 3 mm high and with a central pulp lumen of 2.6 mm in diameter, were filled with five commonly used or potential root-end filling materials. At 24 h, or at 3, 6, or 12 months after filling, leakage along these filling materials was determined under a low headspace pressure of 10 kPa (0.1 atm) using a fluid transport model. During the first 3 months, the percentage of gross leakage (> 20 microliters day-1) increased noticeably for Tytin amalgam (from 20 to 100%) and Super-EBA (from 0 to 55%), whereas it decreased noticeably for mineral trioxide aggregate (MTA; from 55% to 0%). Thereafter, the increased leakage of amalgam and Super-EBA decreased with time, whereas the improved seal of MTA was maintained until the end of the experiment. At 3-, 6-, and 12-month time intervals, both glass ionomer cements (Fuji II and Hi Dense) and MTA showed less leakage than the conventional amalgam and Super-Eba, of which amalgam leaked more.

Decoloration of 1% methylene blue solution in contact with dental filling materials

OBJECTIVES Leakage studies have been performed frequently, since a tight seal provided by various dental fillings has been considered clinically important. The dye penetration experiment using a methylene blue solution as a tracer is one of the most common methods applied in these types of studies. The stability of the colour of methylene blue in contact with six dental filling materials was observed. METHODS Silicon rubber tubes and human tooth roots of 10 mm in length and 1.5 mm inner diameter were filled with amalgam, calcium hydroxide, Cavit, Fuji II, mineral trioxide aggregate, or zinc oxide eugenol, 10 tubes or roots for each material. Groups of five tubes or roots filled with the same material were immersed in 0.8 ml 1% methylene blue dye solution. The optical density of the methylene blue solution before immersion and after 24, 48 and 72 h of immersion was measured in a spectrophotometer at 596 nm. RESULTS The methylene blue solution was found to be decoloured over time by all the test materials (P < 0.01) except for Fuji II, in both silicone tubes and roots. At 24 h, the optical density value of methylene blue decreased by 73% for the Ca(OH)2/silicone group and 84% for the mineral trioxide aggregate/silicone group. CONCLUSION Methylene blue is decoloured by some dental filling materials, which may result in unreliable results for these materials in dye leakage studies.

Microleakage along apical root fillings and cemented posts

STATEMENT OF PROBLEM Coronal leakage of endodontically treated teeth has been found to result in a high failure rate. PURPOSE This study tested leakage along apical root fillings remaining after post space preparation and cemented posts in root canals. MATERIAL AND METHODS A total of 120 human roots were used in the study and divided into six groups, 20 roots for each group. By using a modified fluid transport model, leakage (in microL/hr) along ParaPost dowels that were cemented in the coronal 7 mm of root canals with Fuji Duet, Ketac Cem, Panavia EX, or zinc phosphate cements was compared with that along the coronal 7 mm of conventional root canal fillings. Leakage along the apical 4 mm of root filling remaining after post space preparation was compared with that along the 11 mm root filling before post space preparation. RESULTS More leakage was recorded along the apical 4 mm of root filling than along the 11 mm of original root filling (p = 0.0325). ParaPost dowels cemented with any test cement did not produce more leakage than the 7 mm coronal root filling (p = 0.2145). CONCLUSIONS The apical 4 mm of root canal filling remaining after post space preparation leaks statistically significantly more than the original full-length root canal filling. The leakage created by removal of the coronal part of root canal filling during post space preparation may be compensated by the cemented posts.

Regenerative Endodontic Therapy: A Data Analysis of Clinical Protocols

INTRODUCTION The aim of the present study was to systematically analyze the protocols that have been used in regenerative endodontic therapy and to detect any variations in clinical procedures. METHODS An electronic search was executed in PubMed using appropriate Medical Subject Heading terms covering the period from January 1993 to May 2014. Additional publications from hand searching and the reference section of each relevant article enriched the article list. The relevance of each article was initially evaluated by scanning all titles and corresponding abstracts. The definite inclusion of each article in the study was determined by using specific criteria applied independently by 3 reviewers. RESULTS Sixty relevant publications were finally included. The canal walls were not mechanically instrumented in 68% of the clinical articles. Sodium hypochlorite was included in 97% of the clinical studies either as the only irrigant or in combination with other irrigants. Antibiotic combination paste was used as the intracanal medicament in 80% of the clinical articles. Sodium hypochlorite, chlorhexidine, and EDTA were used in the final irrigation protocol in 75%, 4%, and 13% of the clinical studies, respectively. Neither the creation of a blood clot nor the use of platelet-rich plasma/platelet-rich fibrin was described in 13% of the clinical articles. Mineral trioxide aggregate was used as an intracanal coronal barrier in 85% of the relevant clinical studies. CONCLUSIONS The variability of the clinical protocols applied during regenerative enododontic procedures is considerably high. A thorough analysis of regenerative protocols may constitute an additional source to provide useful clinical considerations for REPs.

Prevalence and Management of Instrument Fracture in the Postgraduate Endodontic Program at the Dental School of Athens: A Five-year Retrospective Clinical Study

The aim of the present clinical research was to investigate the prevalence and management of instrument fracture during root canal preparation by postgraduate students (Department of Endodontics, Dental School of Athens) and to determine the percentage of referred cases with fractured instruments managed by the same students of the program. A retrospective study was conducted by reviewing the dental notes of 1367 patients (2180 endodontic cases, 4897 root canals) treated between October 2001 and June 2006 by endodontic postgraduate students at the Dental School of Athens. Type of tooth and canal, type and length of fractured segments, level of instrument fracture, and management that followed were recorded. The overall prevalence of instrument fracture during root canal preparation by postgraduate students was 1.83%. The prevalence of endodontic cases with fractured instruments referred to the endodontic postgraduates was 7.41%. The prevalence of stainless steel hand and rotary nickel-titanium instrument fracture by postgraduate students were 0.55% and 1.33%, respectively. The prevalence of instruments fractured in the apical third (52.5%) was significantly higher when compared with coronal (12.5%) and middle (27.5%) thirds of the canals. The retrieval or bypass of fractured instruments was most successful in the coronal (100%) and middle (45.4%) thirds when compared with the apical third (37.5%) of the canals. The fracture frequency was higher in retreatment cases in relation to the respective rate of initial therapies. On the basis of the results of this study, the prevalence of endodontic instrument fracture by the postgraduate students was relatively low. The prevalence of fracture of nickel-titanium rotary instruments was more frequent than that of hand instruments. Retrieval or bypass of the fractured instruments in the apical third was less successful.

A Comparative Study of the Effects of Three Root-end Filling Materials on Proliferation and Adherence of Human Periodontal Ligament Fibroblasts

INTRODUCTION The present in vitro study was conducted with the aim of evaluating and comparing the cytotoxic effects of three root-end filling materials, ProRoot mineral trioxide aggregate (ProRoot MTA; Dentsply Tulsa Dental, Memphis, TN), MTA Angelus (Angelus, Londrina, Brazil), and a modified zinc oxide-eugenol cement (Super-EBA; Bosworth Co, Skokie, IL) on human periodontal ligament (PDL) fibroblasts. METHODS PDL cells were cultured in an mineral trioxide aggregate (MTA)- or a Super-EBA-conditioned medium to assess the viability as determined by the trypan blue exclusion assay. The proliferation of the cells was recorded, and the cellular morphology was observed by confocal microscopy. Moreover, PDL cell aggregates were cultured on the substrate surfaces to assess cell adhesion. RESULTS ProRoot MTA was found to be the most biocompatible material, whereas Super-EBA was found to be the most cytotoxic material because it significantly inhibited the cell growth and adherence on its. In the presence of ProRoot MTA, the PDL cell proliferation was almost unaltered. MTA Angelus was found to be more cytotoxic than ProRoot MTA, offering, however, excellent scaffold properties for the adhesion of cell aggregates. CONCLUSIONS Under the conditions of the present study, it seems that commercially available forms of MTA may behave in different ways regarding their proliferative effect on human PDL fibroblasts. ProRoot MTA appears to be the most biocompatible of the three tested materials when considering use for root-end endodontic microsurgery.

Comparison of Bacterial Community Composition of Primary and Persistent Endodontic Infections Using Pyrosequencing

INTRODUCTION Elucidating the microbial ecology of endodontic infections (EIs) is a necessary step in developing effective intracanal antimicrobials. The aim of the present study was to investigate the bacterial composition of symptomatic and asymptomatic primary and persistent infections in a Greek population using high-throughput sequencing methods. METHODS 16S amplicon pyrosequencing of 48 root canal bacterial samples was conducted, and sequencing data were analyzed using an oral microbiome-specific and a generic (Greengenes) database. Bacterial abundance and diversity were examined by EI type (primary or persistent), and statistical analysis was performed by using non-parametric and parametric tests accounting for clustered data. RESULTS Bacteroidetes was the most abundant phylum in both infection groups. Significant, albeit weak associations of bacterial diversity were found, as measured by UniFrac distances with infection type (analyses of similarity, R = 0.087, P = .005) and symptoms (analyses of similarity, R = 0.055, P = .047). Persistent infections were significantly enriched for Proteobacteria and Tenericutes compared with primary ones; at the genus level, significant differences were noted for 14 taxa, including increased enrichment of persistent infections for Lactobacillus, Streptococcus, and Sphingomonas. More but less abundant phyla were identified using the Greengenes database; among those, Cyanobacteria (0.018%) and Acidobacteria (0.007%) were significantly enriched among persistent infections. Persistent infections showed higher phylogenetic diversity (PD) (asymptomatic: PD = 9.2, standard error [SE] = 1.3; symptomatic: PD = 8.2, SE = 0.7) compared with primary infections (asymptomatic: PD = 5.9, SE = 0.8; symptomatic: PD = 7.4, SE = 1.0). CONCLUSIONS The present study revealed a high bacterial diversity of EI and suggests that persistent infections may have more diverse bacterial communities than primary infections.

Effect of 2% Chlorhexidine Gel Mixed with Calcium Hydroxide as an Intracanal Medication on Sealing Ability of Permanent Root Canal Filling: A 6-month Follow-up

The present study was conducted to determine the influence of 2 intracanal medicaments (calcium hydroxide, chlorhexidine gel 2%) when used either alone or combined on the short- and long-term sealing ability of permanent root canal fillings. Ninety human upper central incisors were divided into 4 experimental groups (n=20). All root canals were instrumented in a step-back motion and then treated as follows: group I, root canal dressing with calcium hydroxide for 2 weeks and then obturation with laterally compacted gutta-percha and AH26 sealer; group II, chlorhexidine gel 2% for 2 weeks and obturation as in group I; group III, dressing with a new paste made by mixing calcium hydroxide plus chlorhexidine gel 2% for 2 weeks and obturation as described previously; group IV, immediately obturated with laterally compacted gutta-percha and AH26 sealer. Leakage along root canal fillings was measured using the transport fluid model. Short term measurements were carried out for 3 hours after 24 hours equilibrium establishment. Leakage was measured again at 6 months after the initial measurement. At 3 hours, no significant differences were found among the 4 experimental groups. Long-term measurements showed that also at 6 months no significant differences were observed between the group IV and the other 3 experimental groups. Under the conditions of the present study, it could be supported that none of the medications used seemed to affect negatively neither the short- nor the long-term sealing ability of the tested obturation technique. On the basis of these results and because of its increased antimicrobial action as it is supported in the literature, the new paste made of calcium hydroxide plus chlorhexidine gel 2% can be proposed for use in clinical practice without affecting the sealing ability of root canal obturation.

Combined Endodontic and Surgical Management of a Mandibular Lateral Incisor with a Rare Type of Dens Invaginatus

Dens invaginatus is a developmental malformation of teeth that most commonly affects permanent maxillary lateral incisors. Presence of dens invaginatus in mandibular permanent teeth is relatively rare. The purpose of this report is to describe the combined nonsurgical and surgical management of a mandibular lateral incisor associated with a rare type of dens invaginatus. Pulp involvement of the malformed tooth, periapical abscess, and severe periodontal destruction were observed. The signs (sinus tracts) and symptoms ceased after completion of the treatment. Satisfactory healing of the periradicular lesion was observed at the 6-month and 2-year follow-up examinations.

Apical Barrier Formation After Incomplete Orthograde MTA Apical Plug Placement in Teeth with Open Apex - Report of Two Cases

Two cases are reported in which incomplete placement of 4 mm mineral trioxide aggregate (MTA) plug was performed unintentionally at the apical third of permanent immature teeth with open apex and apical periodontitis. As confirmed radiographically, there were gaps between MTA and dentinal walls along the MTA-dentin interface. After setting of MTA was confirmed, endodontic treatment was completed and access was sealed with composite resin. At 6 to 16 months follow-up examinations, formation of dentin in contact with the MTA surface, as well as apical closure and periapical healing were ideied radiographically for both cases. The results of these cases showed that apical barrier formation and complete periapical healing is possible despite the incomplete apical placement of the MTA plug. This might be due to the biological properties of the MTA. Even so, an incomplete three-dimensional placement of the filling material is not advocated.