Human saliva penetration of coronally unsealed obturated root canals

Studies have shown significant coronal dye and bacterial leakage following exposure of sealed root canals to artificial and natural saliva. The purpose of this study was to determine the time needed for bacteria in natural saliva to contaminate the entire length of root canals obturated by lateral and vertical condensation techniques. Forty root canals were cleaned and shaped using a step-back technique. Thirty root canals were obturated with gutta-percha and root canal sealer using either lateral or vertical condensation techniques. Forty root canals were obturated without a root canal sealer and served as positive controls. After obturation, the coronal 3 mm of five root canals were sealed with sticky wax and served as negative controls. The coronal portions of the filling materials were placed in contact with human saliva and the number of days required for bacteria in saliva to penetrate the entire root canals were determined. No bacterial leakage occurred in the negative control group. Complete bacterial leakage occurred within 2 days in the positive control group. All root canals were recontaminated in less than 30 days. No statistical significant difference was found between the two methods of obturation.     

Obturation of root canals in vivo with a new vacuum technique

It was demonstrated in vitro that it is possible to achieve obturation of the root canal system with a system utilizing a reduced pressure of 15 hPa (15 mbar). The purpose of this study was to develop a procedure to reach a vacuum of at least 15 hPa within root canals in vivo. It was also determined if root canals could be obturated in daily practice with this vacuum technique. After hand instrumentation of the root canals a tooth was prepared for obturation of the canals with the new technique by obtaining a tightly fitting attachment to a vacuum pump. The result showed that it was possible in vivo to reach reduced absolute pressures of 10 hPa in roots and to fill the root canal system with the new system.     

Participation of African Americans in clinical research

Low apical leakage along root fillings following an application of calcium hydroxide was reported in a few methylene blue dye penetration studies. It has been found recently that methylene blue is decolored by calcium hydroxide, indicating that the short penetration of methylene blue may not be due to a tight seal only. Of the 80 roots of human maxillary central incisors used in this study, 40 roots (group 1) received calcium hydroxide root canal dressing whereas another 40 roots (group 2) did not. All the roots were then obturated with gutta-percha and Tubli-Seal sealer. Leakage along 20 filled roots in each group was measured using a modified fluid transport model at 48 h, 2, 4, 8 and 16 weeks after obturation; whereas leakage of another 20 filled roots in each group was measured using dye penetration with 1% methylene blue. Using the fluid transport model, no significant difference was found between the two groups at any time interval (P = 0.4847, 0.3875, 0.9490, 0.4786, 0.9148 respectively after 48 h, 2, 4, 8 and 16 weeks); using the methylene blue penetration method, leakage in group 1 (with root canal dressing) was significantly less than that in group 2 (without root canal dressing) (P = 0.0374). The contradiction in results from the different models indicated that problems existed with the models.     

Incidence of Lightspeed separation and the potential for bypassing

It is important for endodontic instruments to have a low fracture rate. If a fracture does occur, it would be desirable to have the ability to bypass the broken segment and complete the root canal treatment. One hundred sixty-two root canals in 52 maxillary and mandibular first molars were cleaned and shaped with Lightspeed instruments by three endodontists in their private practices. The canals were instrumented using the technique recommended by the manufacturer. All canals were instrumented to at least a size 45 at the working length. Six instruments separated during treatment. All six had been used more times than recommended by the manufacturer. Five of the six were easily bypassed and treatment completed.     

Effect of two obturation techniques on the filling of lateral canals and the main canal

The three-dimensional obturation of the root canal system is widely accepted as a key factor for successful endodontic therapy. The purpose of this study was to evaluate the obturation of lateral canals and the main canal using cold lateral condensation versus the gutta-percha coated rigid carrier. Thirty epoxy blocks with five lateral canals placed at varying angles from the main canal were used. Each experimental group was obturated by a board certified endodontist with clinical experience in the respective obturation technique. The length of gutta-percha and sealer in the lateral canals was measured under a microscope (x30, Unitron) to the nearest 0.5 mm. The blocks were sectioned with an Isomet Plus precision saw (Buehler, Lake Bluff, IL) and copious water irrigation perpendicular to the main canal at the apex, the height of contour, and at 0.8, 1.6 and 2.4 mm from the canal apex. A microscope (x100, Leitz, Switzerland) was used to determine voids. There was significantly (p < .001) more gutta-percha in the lateral canals with the gutta-percha coated rigid carrier technique. In contrast, the cold lateral condensation technique had significantly (p < .001) more sealer in the lateral canals. However, there was no significant (p < .05) difference, in gutta-percha-plus-sealer filling of the lateral canals, between the two techniques. In the apical 1 mm of the main canal there were significantly (p < .011) fewer voids with the gutta-percha coated rigid carrier technique compared to the cold lateral condensation. In the model chosen, the gutta-percha coated rigid carrier technique and the cold lateral condensation technique were equally effective in filling lateral canals. In filling the main canal, however, the coated rigid carrier technique was more effective.     

Scanning electron microscopic evaluation of two compaction techniques using a composite resin as a root canal filling material

The canals of 20 human dental roots were instrumented using a a step- back technique. The smear layer was removed, and the canals were obturated with composite resin. Two different techniques of compaction were used: either vertical or lateral motions were used to condense composite resin inside the root canal that was then photopolymerized layer by layer using the argon laser (488 nm). The beam was delivered into the root canal by means of an optical fiber 320 micrometers in diameter. Longitudinal and cross-sections of the samples and resin replicas of the root canals were examined using a light and scanning electron microscope. Scanning electron microscopic examination revealed that laterally compacted resin fillings showed fewer voids than those obtained by vertical compaction. In both experimental groups, adhesion of the resin to the dentin walls, pulled-out resin tags, microfailure, and resin fracture, leaving a layer of resin associated with the wall surface were observed.     

Influence of membrane oxygenators on the pulsatile flow in extracorporeal circuits: an experimental analysis

The vertical force applied to an endodontic spreader generates stress along the canal walls. Recognizing the potential for this stress may reduce the incidence of vertical root fractures. A photoelastic acrylic model was fabricated to exhibit the stress produced during obturation of curved canals using the lateral condensation technique. Twenty standardized models simulating curved canals (32 degrees) were formed within PL-2 photoelastic acrylic resin blocks. The canals were fitted with a gutta-percha point, and either a stainless-steel or nickel-titanium finger spreader was inserted. An Instron 4502 universal testing machine applied a vertical force of 20 Newtons to the spreader. Quarter wave and polarizing filters were used with backlighting to generate the fringe patterns in the models. Photographs of the resulting stress lines showed that the stainless-steel spreaders created three areas of concentrated stress. The nickel-titanium spreaders induced stress patterns spread out along the surface of the canals, thus reducing the concentration of stress and the potential for vertical root fracture.     

Root canal instruments for manual use: a review

Root canal instruments can be subdivided into instruments made of different alloys (stainless steel, nickel-titanium and nickel-aluminium) and instruments with different geometric forms (e.g., instruments with short cutting segments). Several types of stainless steel and titanium-based instruments are presented and assessed by a review of the current literature. In summary, flexible stainless steel instruments with noncutting tips seem to be a decisive improvement in the development of an ideal root canal instrument. They are superior to titanium-based instruments in both cutting efficiency and instrumentation of curved root canals.     

The role of the centrifugal pump in hemolysis during neonatal extracorporeal support

A study was conducted to evaluate coronal microleakage of Super EBA and Ketac-Endo when used as sealers with single-cone gutta-percha (GP) root canal obturation. The root canals of 24 extracted human teeth were instrumented with flared preparations to a minimum #40 master apical file size. Ten teeth were obturated with a single GP cone and Super EBA as the sealer and ten teeth were obturated with a single GP cone and Ketac-Endo as the sealer. Four teeth were used as controls. Salivary bacterial microleakage studies were conducted to determine whether these sealers could prevent coronal microleakage through the root canal in the absence of a coronal tooth restoration. There was no bacterial penetration through the apical foramen for either sealer tested during the 60-day test period.     

Comparison of two endodontic handpieces during the preparation of simulated root canals

The objective of this in vitro study was to compare and assess two endodontic handpieces during the preparation of simulated root canals. One hundred and sixty simulated root canals in clear resin blocks, of two angles and positions of curvature, were prepared using either Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besan?on, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). Files of 21-mm or 25-mm length were used. When preparing the canals, the files were used either in line with or perpendicular to the canal curvature. Preparation of the canals was carried out using a technique described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including an assessment of the canal preparation time, the deformation or fracture of instruments, loss of canal length, weight loss from the resin blocks and the overall postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic Air handpiece took significantly more time (P < 0.001) to prepare the canals and was associated with both more loss of working length (P < 0.05) and more loss of weight (P < 0.001). Both handpieces created a high percentage of aberrations in the shapes of prepared canals. The MM1500 Sonic Air handpiece created significantly more aberrations than the Excalibur handpiece (P < 0.05 for zip and elbow, P < 0.05 for danger zone and coronal narrow). The effects of the variables, canal curvature, file length and the plane of use of the file, on the performance of the handpieces, were also assessed.     

One-step apexification without calcium hydroxide

Slow growth calcium hydroxide apexification may be clinically impractical in some instances. This case report describes a technique and rationale for single-step use of tricalcium phosphate as an apical plug in an immature permanent root. This method permitted immediate canal obturation and placement of the permanent coronal restoration. A 7-yr follow-up confirmed that this type of apexification could be successful.     

Delayed endodontic and orthodontic treatment of cross-bite occurring after luxation injury in permanent incisor teeth

A case is presented in which combined endodontic and orthodontic therapy was performed in traumatically injured teeth 12 months after an accident. Calcium hydroxide treatment was used to halt any possible resorption during orthodontic treatment. The teeth were repositioned in a desirable manner without any complication by orthodontic treatment. Root canal obturation was accomplished after the completion of active orthodontic treatment. Recall examination 12 months after completion of root canal treatment showed clinical and radiographic evidence of healing.     

An in vitro comparison of thermoplasticised gutta-percha obturation techniques with cold lateral condensation

This study compared the apical sealing ability, obturation time and extrusion of gutta-percha and sealer when root canals were obturated using either cold lateral condensation or one of the three methods using thermoplasticised gutta-percha (Alpha Seal, Thermafil or JS Quick Fill) in vitro. One hundred and thirty-one root canals from 78 extracted human teeth were used; 116 canals were divided into five groups so that they were balanced with respect to prepared canal anatomy, and the remaining 15 canals were used as positive and negative controls. The canals in the first four groups were prepared with hand files using the step-down technique to a standard apical size and flare. The last group was prepared using engine-driven rotary nickel-titanium files (McSpadden) to a similar apical size and flare. One of the four obturating techniques was used to fill the canals in each of the first four groups. The fifth group was obturated using the Alpha Seal technique. The roots were immersed in india ink, demineralised and rendered transparent to assess the extent of maximum lincar dye penetration. The Alpha Seal groups had the highest number of specimens without any leakage. There was a significant difference in the proportions of specimens that did not leak when the Alpha Seal (P < 0.01) and cold lateral condensation groups (P < 0.05) were compared with JS Quick Fill. Cold lateral condensation had a higher proportion of specimens with leakage in canals with curvature greater than 20 degrees than in canals with curvatures less than 20 degrees (P < 0.05). The curvature of canals had no effect on the sealing ability of the other techniques. The method of canal preparation had no effect on the sealing ability of Alpha Seal. Alpha Seal, Thermafil and JS Quick Fill were significantly quicker to perform than cold lateral condensation.     

Seroprevalence of hepatitis B virus among school-age children in the Stann Creek District of Belize, Central America

A conservative approach to endodontic treatment of a maxillary canine with dens invaginatus is presented. Pulp involvement and periapical abscess subsequent to contamination through the invagination space occurred at an early dental age before root completion. Treatment was initially to achieve apical closure before the completion of root canal treatment. Apexification with calcium hydroxide was performed to provide favorable conditions for healing and eventually for successful obturation. Difficulties and entanglements posed by the complex internal morphology and the root developmental stage are presented. Clinical considerations are discussed and a treatment approach used to overcome those obstacles described.     

Evaluation of the Water Delivery Performance of the Menemen Left Bank Irrigation System Using Variables Measured On-Site

This study determines the water delivery performance at secondary and tertiary canal level of the Menemen Left Bank Irrigation system, an open canal irrigation system located in Turkey, for the irrigation seasons of the years 2005–2007. At secondary canal level, water supply ratio was used, and at tertiary level, the indicators of adequacy, efficiency, dependability, and equity were used. In calculating these indicators in this study, the amounts of water diverted to the canals, efficiency of water conveyance, and of water application were measured. Of these indicators, the water supply ratio was determined for the secondary canal, and the other indicators were determined for a total of six selected tertiary canals at the head, middle, and lower end of the secondary. At secondary level, the water supply ratios obtained to total irrigation water requirements for the months of July and August, when requirement for irrigation water is at a maximum, was determined to be less than one, while the water supply ratios obtained to net irrigation water requirement was found to be more than one. With regard to water delivery performance at tertiary level, adequacy, efficiency, dependability, and equity were found to be poor for each of the three years of the study, with efficiency rising to “fair” level only in 2005. In order to raise the water delivery performance of the system, it is necessary to reduce water conveyance losses to increase the water application efficiency, to prepare water distribution plans which take in tertiary canals, and to measure and monitor the water diverted to the canals.     

Scanning electron microscopic evaluation of the cleanliness of a new ultrasonic root end preparation

Recently introduced ultrasonic instrumentation techniques for root end preparation have revolutionized the field of endodontic surgery. The specially designed tips offer improved access to the root end and create more conservative root and preparations while decreasing the amount of retained debris. This study compared the cleanliness of root end preparations made using ultrasonic instrumentation with that of those prepared in a traditional manner using a microhandpiece bur. We used 10 extracted maxillary human premolars and molars. After cleaning, shaping, and obturation of the root canals, a 3 mm root end resection perpendicular to the long axis of the root was performed with a carbide fissure bur. The roots were randomly divided into two groups and root end preparations were made using the two aforementioned techniques. The roots were longitudinally split and sputter-coated with gold for scanning electron microscopic study. Three independent dentists used a standardized grading system to evaluate the cleanliness of the root end preparations. The ultrasonic preparation had significantly less superficial debris and a thinner smear layer than the microhandpiece preparation (p < 0.05). There were no significant differences between the canal and isthmus portions of the root end preparations within each group in either superficial debris or smear layer. This indicates that cleaner surfaces for root end cavities are created using ultrasonic retrotips than using microhandpiece burs.     

Obturation of a C-shaped canal using an improved method of warm lateral condensation

Pilot studies conducted by the authors seem to indicate that obturation of a root canal system by the lateral condensation of gutta-percha using an electrically heated spreader results in a more homogeneous mass of gutta-percha than standard lateral condensation. This article describes an improved variation which prevents inadvertent dislodgement of the mass of gutta-percha during the obturation. The authors refer to this technique as "zap and tap" and a case report describes its use to obturate a C-shaped canal system of a mandibular second molar.     

Holmium: YAG laser resection of prostate (HoLRP) for patients in urinary retention

The differing morphological manifestations of the root canal system have been the subject of research, and the incidence of various shapes of root canal systems has been classified. The present case describes the root canal treatment of a rare morphological pattern, namely a mandibular permanent canine with three root canals. No report of a similar case has been published previously.     

Root canals in two-rooted maxillary second molars

The aim of this study was to register the root canal number, root canal position, and root canal cross-section in human two-rooted, permanent maxillary second molars. One hundred and fifty-nine such teeth extracted in Denmark were cross-sectioned at the mid-root level and apically in accordance with precise guidelines. The observations were made in a stereomicroscope, corresponding to the above-mentioned section levels. At mid-root there were two canals present in 11% of the teeth examined; the canals were located mesially and distofacially, mesiofacially and distally, or facially and lingually. Three canals positioned mesiofacially, distofacially, and lingually were observed in 89% of the teeth. At the same level 62% of the canal cross-sections were noncircular, some being, for instance, C-shaped, whereas 38% of the cross-sections were circular. Apically, two canals were found, representing 19% of the teeth, with the canal position as at mid-root; 81% of the teeth were three-canaled with the same canal position as at mid-root. At the apical level 60% of the canal cross-sections were noncircular, whereas 40% of the cross-sections were circular.     

Incomplete calcium hydroxide removal from the root canal: a case report

This case demonstrates failure of root canal treatment of a maxillary central incisor following incomplete mechanical removal of a Ca(OH)2 intracanal dressing and subsequent resorption of the material from the apical portion of the root canal. Retreatment some 4 years later involved the removal of the contents of the root canal and permanent obturation by lateral condensation of cold gutta-percha with a sealer. Follow-up showed complete periradicular bone healing with a lamina dura evident. An explanation of the processes involved is offered, based upon histopathological and microbiological evidence in the literature.