Paul R. Wesselink

Detection of Vertical Root Fractures in Endodontically Treated Teeth by a Cone Beam Computed Tomography Scan

Our aim was to compare the accuracy of cone beam computed tomography (CBCT) scans and periapical radiographs (PRs) in detecting vertical root fractures (VRFs) and to assess the influence of root canal filling (RCF) on fracture visibility. Eighty teeth were endodontically prepared and divided into four groups. The teeth in groups A and B were artificially fractured, and teeth in groups C and D were not. Groups A and C were root filled. Four observers evaluated the CBCT scans and PR images. Sensitivity and specificity for VRF detection of CBCT were 79.4% and 92.5% and for PR were 37.1% and 95%, respectively. The specificity of CBCT was reduced (p = 0.032) by the presence of RCF, but its overall accuracy was not influenced (p = 0.654). Both the sensitivity (p = 0.006) and overall accuracy (p = 0.008) of PRs were reduced by the presence of RCF. The results showed an overall higher accuracy for CBCT (0.86) scans than PRs (0.66) for detecting VRF.

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.

Efficacy of three techniques in cleaning the apical portion of curved root canals

Various techniques for root canal instrumentation may have different effects in cleaning curved root canals, especially their apical portions. One hundred thirty-five mesiobuccal canals with an average curvature of 25 degrees from human mandibular molars were treated with step-back, crown-down pressureless, or balanced-force techniques with 2% sodium hypochlorite used as an irrigant. The cleaning efficacy of these techniques was evaluated by counting the remaining surface debris under a stereomicroscope with a calibrated eyepiece micrometer. The results indicated that the apical portion of the canal was less clean than the middle and coronal portions regardless of the technique performed and that the balanced-force technique produced a cleaner apical portion of the canal than did the other techniques studied.

The ability of different nickel-titanium rotary instruments to induce dentinal damage during canal preparation

The purpose of this study was to compare the incidence of dentinal defects (fractures and craze lines) after canal preparation with different nickel-titanium rotary files. Two hundred sixty mandibular premolars were selected. Forty teeth were left unprepared (n = 40). The other teeth were prepared either with manual Flexofiles (n = 20) or with different rotary files systems: ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland), ProFile (Dentsply-Maillefer), SystemGT (Dentsply-Maillefer), or S-ApeX (FKG Dentaire, La Chaux-de-Fonds, Switzerland) (n = 50 each). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. There was a significant difference in the appearance of defects between the groups (p < 0.05). No defects were found in the unprepared roots and those prepared with hand files and S-ApeX. ProTaper, ProFile, and GT preparations resulted in dentinal defects in 16%, 8%, and 4% of teeth, respectively. Some endodontic preparation methods might damage the root and induce dentinal defects.

Leakage along apical root fillings in curved root canals. Part I. Effects of apical transportation on seal of root fillings

Occurrence of apical transportation (AT) may complicate the root filling procedure and result in a compromised seal. In part I of this study, human mandibular premolars with single, curved (21 to 39 degrees), or straight canals were prepared by Lightspeed or a step-back hand filing technique. An AT index was determined using a double exposure radiographic technique. The prepared canals were obturated using lateral condensation of gutta-percha. Leakage along the apical 3 mm of root filling was measured with a fluid transport model. After hand filing, AT and perforation occurred in 87% of the curved canals. The AT indices were > or = 0.4 mm. After Lightspeed preparation, AT occurred in only 19% of the curved canals. The hand filing/curved group leaked statistically significantly more than the hand filing/straight and Lightspeed/curved groups (p = 0.002). We conclude that occurrence of AT is a factor that negatively influences the apical seal when curved canals are obturated by lateral condensation of gutta-percha.

Comparison of Five Cone Beam Computed Tomography Systems for the Detection of Vertical Root Fractures

INTRODUCTION This study compared the accuracy of cone beam computed tomography (CBCT) scans made by five different systems in detecting vertical root fractures (VRFs). It also assessed the influence of the presence of root canal filling (RCF), CBCT slice orientation selection, and the type of tooth (premolar/molar) on detection accuracy. METHODS Eighty endodontically prepared teeth were divided into four groups and placed in dry mandibles. The teeth in groups Fr-F and Fr-NF were artificially fractured; those in groups control-F and control-NF were not. Groups Fr-F and control-F were root filled. CBCT scans were made using five different commercial CBCT systems. Two observers evaluated images in axial, coronal, and sagittal reconstruction planes. RESULTS There was a significant difference in detection accuracy among the five systems (p = 0.00001). The presence of RCF did not influence sensitivity (p = 0.16), but it reduced specificity (p = 0.003). Axial slices were significantly more accurate than sagittal and coronal slices (p = 0.0001) in detecting VRF in all systems. Significantly more VRFs were detected among molars than premolars (p = 0.0001). CONCLUSIONS RCF presence reduced specificity in all systems (p = 0.003) but did not influence accuracy (p = 0.79) except in one system (p = 0.012). Axial slices were the most accurate in detecting VRFs (p = 0.0001).

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.

Laser-activated irrigation within root canals: cleaning efficacy and flow visualization.

AIM To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. METHODOLOGY Root canals with a standardized groove in one canal wall filled with dentine debris were irrigated with syringe irrigation, ultrasonically or laser-activated irrigation (LAI) using 2% sodium hypochlorite as irrigant. The quantity of dentine debris after irrigation was determined. Visualization of the fluid dynamics during activation was achieved using a high-speed camera and a glass model. RESULTS Laser-activated irrigation was significantly more effective in removing dentine debris from the apical part of the root canal than passive ultrasonic irrigation or hand irrigation when the irrigant was activated for 20 s. CONCLUSIONS The in vitro recordings suggest that streaming, caused by the collapse of the laser-induced bubble, is the main cleaning mechanism of LAI.

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.

Endodontic outcome predictors identified with periapical radiographs and cone-beam computed tomography scans

INTRODUCTION The outcome predictors identified with data from periapical radiographs (PA) and cone-beam computed tomography (CBCT) scans might not be the same. This retrospective study evaluated various factors that might affect the outcome of root canal therapy. METHODS In total, 115 teeth (143 roots) with vital pulps were endodontically treated and followed up 2 years after treatment. Multivariate logistic regression was performed on the data from PA or CBCT to analyze outcome predictors. RESULTS At recall, PA detected periapical lesions in 18 roots (12.6%), as compared with 37 on CBCT images (25.9%). The length and density of root filling determined by PA and CBCT were often different (p < .001). Overall, 20 of the 25 short root fillings (80%) diagnosed by PA appeared as flush fillings on CBCT images. PA revealed 23 root fillings (16.1%) with voids, as compared with 66 on CBCT images (46.2%). When findings from PA were analyzed, density and apical extent of root filling were identified as predictors (p < .05). When findings from CBCT were analyzed, density of root filling and quality of coronal restoration influenced the outcome significantly (p ≤ .001), whereas gender, tooth type, root curvature, number of visits, CBCT-determined apical extent of root filling, and use as abutment did not (p > .1). CONCLUSIONS Treatment outcome, length and density of root fillings, and outcome predictors as determined with CBCT scans might not be the same as corresponding values determined with PA.