Effectiveness of oxidative potential water as a root canal irrigant.

AIM: The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigant, based on its ability to remove the smear layer and/or debris from instrumented root canals. METHODOLOGY: One hundred and twenty root canals from extracted human maxillary incisors were instrumented using a conventional step-back technique with irrigation from sodium hypochlorite (NaOCl) or oxidative potential water (OPW). After instrumentation, the canals were irrigated by syringe or ultrasound using 15% EDTA or OPW as an irrigant. The volume of each irrigant used for syringe irrigation was 10, 20, and 30 mL, respectively, whilst the duration for ultrasonic irrigation was 1, 3, and 5 min, respectively. After irrigation, each root was split longitudinally in two with cutting pliers, and the specimens were prepared for SEM observation. The presence of debris and smear layer on each canal wall was assessed using a three-point scale for each parameter. RESULTS: Smear layer was effectively removed with EDTA both introduced via syringe and via ultrasonic irrigation. A similar effect was observed with OPW via syringe irrigation following instrumentation with 5% NaOCl. The canal walls in any of these cases showed open and patent dentinal tubules following smear layer removal. Some specimens irrigated with EDTA exhibited the effect of demineralization on the dentine resulting in funnelling of tubule orifices. Syringe irrigation was more effective in smear layer removal, except for ultrasonic irrigation with 15% EDTA, whilst ultrasonic irrigation was more effective in debris removal including the use of OPW as irrigant following instrumentation with 5% NaOCl. Neither syringe nor ultrasonic irrigation with OPW following instrumentation with OPW removed smear layer or debris effectively. CONCLUSIONS: The most effective irrigation technique for smear removal was 15% EDTA irrigation by means of syringe following instrumentation with 5% NaOCl solution. However, the most effective irrigation technique for debris removal was ultrasonic irrigation regardless of irrigant used. OPW irrigation by means of syringe following instrumentation with 5% NaOCl showed a similar effect to that of 15% EDTA irrigation for removal of smear layer and debris.

Canal configuration of the mesiobuccal root of the maxillary first molar of a Japanese sub-population.

AIM: The aim of this study was to determine the percentage of anatomical canal configurations of the mesiobuccal root of the maxillary first molar in Japanese patients. METHODOLOGY: Three hundred teeth were obtained from general dentists who knew absolutely that they were extracted from Japanese patients. The distobuccal and palatal roots were amputated for radiographic convenience. Preoperative radiographs were taken of the remaining crown and mesiobuccal root (MBR) from mesiodistal and buccopalatal directions for each tooth. Routine endodontic access cavities were prepared and size 08 files were placed through the orifice into the MBR until they were seen at the apex. In some cases preparation of the canal orifice with a long shank round burr was necessary to gain access. In seven teeth, no access to the apex was possible and these teeth were eliminated. In the other 293 teeth, the MBR canal(s) was (were) enlarged up to size 15 file. If another canal opening was found at the apex a 08 file was inserted into the second opening and passed coronally. Postoperative radiographs with file(s) in place were taken from the two directions, as before. RESULTS: Of the 293 teeth, 123 (42.0%) were Type II, 89 (30.4%) showed Type III systems and 10 (3.4%) were Type IV. Suggestions for identification and treatment of the second canal in the MBR are presented. CONCLUSIONS: The proportion of cases with two canals in the mesiobuccal root of maxillary first molars from Japanese patients was high and similar to that described from studies of other ethnic populations.

The C-shaped mandibular second molar: incidence and other considerations. Members of the Arizona Endodontic Association.

Although its most common configuration is two roots and three canals, the mandibular second molar may have many different combinations. Cooke and Cox were the first to describe a single-rooted mandibular second molar with a continuous slit connecting some or all of the canals. If sectioned horizontally through the main portion of the root, this slit had the shape of the letter "C." Other papers were written and lectures were presented on this and similar entities, but its frequency and significance have remained the object of speculation because large numbers of these teeth have not been categorized. By combining the efforts of an endodontic study club, 811 endodontically treated mandibular second molars were evaluated. Sixty-two of these (7.6%) were identified as C-shapes. Other aspects of this configuration were also investigated.

Controversies in clinical endodontics: Part 2. Single-appointment vs multiple-appointment treatment.

Endodontics is no stranger to controversies. For most of the first 50 years of the 20th century, a cloud hung over endodontic therapy of any kind, as problems with the focal infection theory were attributed to pulpless teeth causing a wide variety of maladies. Even recently, endodontic treatment has been attacked as being responsible for many chronic and acute illnesses, despite a multitude of information to the contrary. The controversies we discuss here, however, have nothing to do with the decision to treat, where we have no doubt as to the efficacy for therapy, but rather how such treatment should be rendered. Controversies have raged in the past, such as silver points vs gutta-percha as the canal filling material of choice, and to culture or not to culture, to name just two. The subjects discussed in this series of articles are those that have come up much more recently or older topics that have returned as areas for disagreement: (1) lateral canals: filling and significance; (2) single-appointment vs multiple-appointment treatment; (3) filling from the open position; and (4) calculation of working length. This article addresses single-appointment vs multiple-appointment treatment.

Effectiveness of eucalyptol and d-limonene as gutta-percha solvents.

Eucalyptol and d-limonene were evaluated for their ability to serve as a substitute solvent for chloroform. The amount of time required to soften and remove the gutta-percha in 72 instrumented and filled simulated root canals in epoxy blocks was measured. After preparation to the apices of the block canals with a #60 file, four different filling techniques were used. These obturations were softened with each solvent and then removed, first using a #15 Hedstrom file inserted to full working length, and then removing the remaining filling mass with a #60 reamer. The two instrument placements were timed: one for the Hedstrom file insertion to the apex and the other for the reamer to remove the filling material. Neither the different solvents nor the filling techniques had a significant effect on the times required for the H-files to reach the apex. However, the times for the reamer to remove the filling materials were effected both by the filling techniques and the solvents used.

Controversies in clinical endodontics: Part 3. Filling from the open position.

Controversies have been common in the clinical treatment of endodontically involved teeth for many years. This series of articles discusses the advantages and disadvantages of three of the major disagreements in the field at this time. They are: (1) What is the significance of lateral canals and how are they best filled? (2) Should treatment be completed in a single appointment or should multiple appointments be involved? And (3) Can the canal(s) be filled after the tooth is left open or should such treatment be avoided? This article discusses filling from the open position.

Removal of smear layer in the root canal using oxidative potential water.

We investigated oxidative potential water (OPW) for its ability to remove the smear layer using a scanning electron microscope. OPW has been studied mainly in Japan and is known to suppress bacteria and viruses without harming living systems. We found that OPW used as in irrigant during and after root canal instrumentation is as effective as 5% NaOCl or 17% EDTA for opening and keeping patent the dentinal tubules.

Controversies in clinical endodontics: Part 1. The significance and filling of lateral canals.

Controversies have been common in the clinical treatment of endodontically involved teeth for many years. This series of articles discusses the advantages and disadvantages of four of the major disagreements in the field at this time. They are: (1) What is the significance of lateral canals and how are they best filled? (2) Should treatment be completed in a single appointment or should multiple appointments be involved? (3) Can the canal(s) be filled after the tooth is left open or should such treatment be avoided? (4) What is the best way to calculate the working length? This article discusses the centerpiece controversy-lateral canals. Subsequent articles will consider the other three subjects.

The use of non-ISO-tapered instruments for canal flaring.

Before 1958, endodontic instruments had no standardized shape or pattern between successively larger sizes. Then Ingle established a nomenclature for the parts of the instrument and a standardization for the length of flutes, taper, and the relationship between successive sizes. His recommendations were endorsed and then supervised by the International Standards Organization (ISO). Recently several instruments have been introduced with greater than ISO-standard taper in order to produce preparations with increased taper from the tip to the orifice. The modifications would produce better and cleaner preparations leading to easier-to-place canal-filling materials. Methods for using these newer file systems and changes from the manufacturers' instructions for safer use are presented.

Sealing ability of thermoplasticized gutta-percha fill techniques as assessed by a new method of determining apical leakage.

One hundred fifty-nine extracted single-rooted maxillary human teeth were instrumented and randomly divided into nine groups of 17 teeth each and 6 control teeth. Experimental groups were obturated with Thermafil, Obtura II, Ultrafil Regular Set gutta-percha, and Ultrafil Firm Set gutta-percha, each with or without root canal sealer. A control group was obturated using the lateral condensation technique and sealer. Teeth were immersed in a resorcinol-formaldehyde resin for 5 days at 4 degrees C, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were then sectioned horizontally at 1.5, 2.5, and 3.5 mm from the anatomical apex, and examined under a stereomicroscope at x25 magnification. The resin filled the spaces in the gap between the canal wall and the gutta-percha and this was measured at each of the three levels. The ratio of the area of the resin to the total area of the canal was obtained as the mean leakage area. The results showed no significant difference in the mean leakage area at the same level for the different obturation materials. However, the leakage was significantly less for all materials when root canal sealer was used.

Preparation of curved canals using a combined hand-filing, ultrasonic technique.

Because of the difficulties involved in endodontic preparation of curved canals, many techniques have been suggested using mechanical means to improve final results. Ultrasonics have been used in dentistry for many years as adjuncts for cleaning instruments and as aids in scaling during periodontal treatment. Recent reports on their use in canal preparation have indicated that cleaner canals were obtained. This has led to attempts at using this instrument in curved canals. In this study, preparation with ultrasonics alone in canals of extracted human teeth with curvatures of 30 degrees or greater led to severe straightening, zipping, and strip perforations. The use of ultrasonics more coronally, with hand filing at the apex, avoids these problems. This article presents a step-by-step technique for a combination of hand filing with ultrasonics preparation.

Nonsurgical re-treatment of endodontic failures.

Endodontic treatment has a very high percentage of success. When failures did occur, many were re-treated with surgery, although nonsurgical re-treatment often was an option. Recently, improvements in instruments for use in endodontic surgery have increased the ability to perform such re-treatments. Even so, this author believes that nonsurgical re-treatment is preferable to surgical intervention whenever possible because of the greater comfort to the patient and the increased indication of failure for amalgam reverse fillings. Advice for recall appointments and evaluations and the correct procedures for re-treating common failures without surgery are presented. These include failures caused by short or incomplete canal fillings, overextended canal fillings, untreated major canals, and chronically draining teeth.

Canal configuration of the mesiobuccal root of the maxillary second molar.

The purpose of this study was to investigate the canal configuration in the mesiobuccal root of the maxillary second molar. The canal configuration of the mesiobuccal root of the maxillary second molar need not be the same as that of the maxillary first molar. Several studies have been attempted to clarify the configuration of the second molar, usually via postoperative evaluation, sectioning, or radiography. To follow more closely the clinical procedure, this study involved access cavity preparation and radiographs taken with files in place. Of the 73 extracted maxillary second molars investigated, 67 teeth (91.8%) had 3 roots whereas 6 teeth (8.2%) had 2 roots. In the three rooted teeth, the mesiobuccal roots of 40 (59.7%) were classified as type I (single canal from orifice to apex), 14 (20.9%) were type II (two canals merging short of the apex into a single canal at the apex), 11 (16.4%) were type III (two separate and distinct canals from orifice to apex), and 2 (3%) were type IV (single canal at the orifice, dividing in midroot into two canals exiting at the apex).

Endodontic therapy on the mandibular second molar: easiest to treat of the difficult, molar teeth.

Molar teeth present more problems during endodontic therapy than do bicuspid or anterior teeth. The major reasons for this are that molars can have complicated canal systems with unexpectedly large numbers of teeth with four canals, and they often have quite curved canals, which are more difficult to prepare and fill. The mandibular second molar generally is the easiest of these difficult teeth to treat, but they do have some areas of complication, too. The mesial root almost always has two--not one--canals and a rarely described condition, the C-shaped canal system, may be present.

Combined orthodontic-endodontic therapy: case report of orthodontic movement of a recalcified lateral incisor.

Unlike most cases of combined orthodontic and endodontic therapy that have been reported, in this case endodontic treatment with calcium hydroxide-induced calcification was utilized prior to orthodontic treatment. A 14-yr-old female required orthodontic therapy due to anterior crowding. Preoperative periapical radiographs indicated that the maxillary right lateral incisor demonstrated advanced lateral root resorption of the distal surface. It was decided to use calcium hydroxide therapy to halt any further resorption prior to orthodontic movement. Approximately 1 yr was required to gain calcification, fill the canal with gutta-percha, and place the maxillary closing arch. Subsequent orthodontic treatment did align the teeth in a desirable manner without jeopardy to the recalcified root.

Survival of the endodontic endosseous implant.

The endodontic endosseous implant (EEI) enjoyed wide use in the United States after it was introduced in the 1960's. For various reasons including incorrect case selection, improper use of the materials, and poor preparation for the implant a high number of failures resulted. Following opposition by some members of the dental community, the procedure fell into disuse. The authors of this article had treated a number of cases with the endodontic endosseous implant from 1965 to 1975, many of which did fail. However, we have noted some remarkable very long-term successes with the technique, two of which are presented here. We suggest that the endodontic endosseous implant should not be discarded totally, but, with further research to improve the materials and technique, it still may be used in carefully selected cases.

Changes in cell proliferative activity in granulation tissue invading the root canal.

Root canal models were implanted in rats in order to investigate histologically the movement of granulation tissue invading apical canals and dead spaces and changes in cell proliferative activity as indicated by 3H-thymidine. The models were prepared to have 1, 2, and 3 mm apical canals, with and without dead spaces, to simulate preparations short of the apex and obturation to several levels. After 12 wks implantation of the models without dead spaces, granulation tissue invading 1 mm apical canals did not degenerate and cell proliferative activity remained high. However, tissue invading the 2 and 3 mm apical canals tended to be necrotic and cell proliferative activity was decreased. In the models with dead spaces, the tissue in the 1 and 2 mm apical canals developed and invaded the dead spaces, and still possessed proliferative activity 12 wks after implantation. In contrast, the tissue in the 3 mm apical canals did not invade the dead spaces, even after 12 wks, and no proliferative activity was observed.

Accuracy of an electronic apex locator: a clinical evaluation in maxillary molars.

Identifying the point of apical termination in endodontic therapy is of indisputable importance. In this study, the accuracy of an electronic apex locator was clinically evaluated in 26 maxillary molar teeth, and comparisons were made to the radiographic and direct anatomical measurements of tooth length. The results indicated that a higher percentage of acceptable measurements were obtained by the radiographic method as compared with the electronic method (88.5% to 73.1%). Additionally, inaccurate electronic estimates were long in every instance. The results of this study do not support the replacement of radiographs with electronic devices in endodontic therapy.