The effect of root resection on the sealing property of root canal obturations

Comparison of clinical outcome of periapical surgery in endodontic and oral surgery units of a teaching dental hospital: a retrospective study

OBJECTIVES

The aims of this retrospective study were (1) to compare the outcome of periapical surgery performed in endodontic and in oral surgery units of a teaching dental hospital and (2) to evaluate the influence of factors affecting outcome.

STUDY DESIGN

A total of 176 teeth (endodontic unit, 83; oral surgery unit, 93) surgically treated more than 4 years previously were examined clinically and radiographically by means of strict criteria. Multiple logistic regression analysis was used.

RESULTS

The rate of complete healing for patients treated in the endodontic unit (37.4%) was significantly (P = .009) higher than that for patients treated in the oral surgery unit (19.4%). The technical quality of surgery (P < .001), placement of root-end filling (P = .039), absence of a preoperative periapical lesion (P = .042), absence of a post (P = .047), and presence of an adequate coronal restoration (P = .056, odds ratio = 3.71) had significant effects on treatment outcome.

CONCLUSION

The technical quality of periapical surgery, the presence of a periapical lesion, and adequate apical and coronal seal are important prognostic determinants of successful periapical surgery.

A scanning electron microscopic evaluation of root surfaces and the gutta-percha interface following root-end resection in vitro

AIM

The aim of this study was to evaluate the effects that various commonly used instruments have on root surface morphology, the obturating material, and the interface between the obturation and the root canal walls following root-end resection in vitro.

METHODOLOGY

Sixty human single-rooted teeth with fully formed apices were collected and decoronated. The root canals were instrumented, and then obturated with thermoplasticized gutta-percha using AH-26 as the sealer. The roots were randomly divided into 12 different groups, and apical root-end resections were performed using eight different instrument configurations, and two different directions in which the bur moved across the root face in relation to its direction of rotation. Epoxy resin replicas of the resected root ends were examined using scanning electron microscopy.

RESULTS

Each instrument produced a characteristic surface finish on the resected root end that mirrored its cutting profile. Irrespective of the design of the bur used, smearing and shredding of the gutta-percha across the root face occurred only when the handpiece was moved across the root face in reverse direction in relation to the direction of rotation of the bur.

CONCLUSIONS

To ensure minimal disruption and distortion of the root filling and to prevent shredding of the gutta-percha interface, care should be taken to ensure that the final pass of the bur across the root canal is in the correct direction in relation to its direction of rotation.

Microleakage of super-EBA with and without finishing as determined by the fluid filtration method

Super-EBA (SEBA) has been used as a root-end filling material because of its superior sealing properties and clinical success. The purpose of this study was to evaluate whether finishing SEBA after it had set would affect the apical seal. Sixty-five extracted maxillary anterior teeth were instrumented and obturated with a single gutta-percha master cone. The root end was resected, and a 3 mm deep root-end preparation was made using ultrasonic tips. Teeth were randomly divided into three groups. Group 1 received SEBA and was finished with a 30-flute high-speed finishing bur. Group 2 received SEBA, which was cold-burnished with a ball burnisher. Temporary Endodontic Restorative Material was used as the negative control in group 3. Microleakage (microliter/min) was measured under 10 psi using the fluid filtration method at days 1, 7, 30, 90, and 180. SEBA/finished exhibited significant microleakage at day 1 when compared with the burnished group. The differences in leakage were not significant at any other time period.

Comparison of ultrasonic and high-speed-bur root-end preparations using bilaterally matched teeth

The purpose of this study was to compare ultrasonic and high-speed-bur root-end preparations. Seventy-six roots from 29 bilaterally matched pairs of human teeth in cadavers were used in this study. In group 1 ultrasonic preparations were made in 38 roots and filled with amalgam. In group 2 high-speed bur preparations were made in 38 roots and filled with amalgam. The size of the bony crypt was measured and the teeth were extracted and radiographed mesial-distally and buccal-lingually. None of the root-end preparations resulted in root perforation. The mean mesial-distal minimum depth of ultrasonic and high-speed bur preparations were 2.11 mm and 1.39 mm, respectively. The mean buccal-lingual minimum depth of preparation was 2.51 mm for the ultrasonic and 2.05 mm for the high-speed bur preparations. The depth of the ultrasonic preparations was significantly greater for both measurements. A significantly greater bevel angle was associated with the bur preparations, 35.1 degrees versus 16.0 degrees for the ultrasonic preparations. The incidence of ultrasonic root-end preparations deviating from the uninstrumented canal spaces was found to be 2.6%. All bur root-end preparations were at an acute angle to the long axis of the root. The bony crypt size for bur preparations was significantly greater than that for ultrasonic preparations.

A comparison between two root end preparation techniques in human cadavers

The purpose of this study was to compare ultrasonic and bur root end cavity preparations with regard to retention, cleanliness, and root canal parallelism. Twenty anterior teeth from human cadavers were instrumented and obturated with gutta-percha and sealer. After raising a full-thickness flap, the apices of the roots were exposed and beveled at a 45-degree angle. Half of the apical cavities were prepared with an appropriate sized Carr alloy tip energized by an Amadent Ultrasonic unit. The other half was prepared with an inverted cone bur in a slow-speed handpiece. The teeth were then extracted, sectioned longitudinally, photographed, and scanning electron micrographs examined. The ultrasonic cavities produced more parallel walls and deeper depths for retention. In addition, the ultrasonic tips followed the direction of the canals more closely than those prepared by burs. Scanning electron microscopic examination of the cavity wall showed presence of cleaner surfaces of root end cavities prepared by ultrasonic tips than those made with burs.

Management of the resected root end: a clinical review

Careful management of the resected root end during endodontic surgery is critical to the overall success of the case. After resection, the root structure presents with multiple anatomical variations and considerations at both a macroscopic and microscopic level. These include root outline, canal anatomy, dentinal tubule configuration, presence of a smear layer and root canal filling material. Proper assessment of these variables will dictate the best methods for root-end management, along with the attainment of an anatomically compatible root face for optimal healing of the periradicular tissues.

Apicectomy of posterior teeth--a clinical study

Studies evaluating periapical surgery of posterior teeth are relatively few. A retrospective study of 32 apicectomies on posterior teeth using both clinical and radiographic means yielded a success rate of 62 per cent. There were five cases (16 per cent) of failure, the majority of which presented as delayed infection between three and six months following surgery. Post-surgical review of at least six months is recommended. Anatomical considerations for posterior tooth apicectomy and the necessity for retrograde fillings are discussed.

Biocompatibility of retrograde filling materials in the ferret canine. Amalgam and IRM

Periapical tissue response to retrograde fillings of amalgam and IRM were compared in the mandibular canine of the adult male ferret. Teeth were cleaned and shaped with a standard technique and obturated with gutta-percha. The root apex was then exposed and retrofillings were placed. The animals were grouped according to observation periods of 5, 10, and 15 weeks. At the proper time the animals were killed and the lower canine tooth along with the surrounding bone was removed. The tissue blocks were examined clinically, radiographed, and prepared for histologic examination. The clinical and radiographic examination indicated both materials to be well tolerated by periapical tissues. Microscopic examination of amalgam specimens showed a decrease in inflammation and the formation of a fibrous capsule over the 15-week period. IRM specimens showed persistent inflammation and slower healing potential.

Retrograde approaches in endodontic therapy

The routine use of retrograde fillings during apical surgery, as well as the material of choice for that purpose, have been debated. A retrograde filling is placed so as to seal an infected root canal causing periapical pathosis. Therefore, retrograde root canal fillings should be performed routinely during apical surgery regardless of the apparent technical quality of the root canal obturation, unless orthograde endodontic treatment is performed in conjunction with surgery. When orthograde treatment is not performed, retrograde root canal filling enhances the prognosis of apical surgery. An array of potential retrograde filling materials have been extensively investigated in vitro and in vivo. Once that the biocompatibility of the materials is confirmed a clinical comparison, rather than in vitro sealability studies, is the most valid evaluation method. Some of the difficulties encountered in long term clinical studies in patients may be avoided in animal studies. The review of the relevant literature of the past decade suggests that amalgam used in conjunction with cavity varnish is the retrograde filling material of choice. It must be stressed, however, that retrograde filling is not comparable to debridement and obturation of the entire root canal. Therefore, when the only way to approach the root canal is from the apical direction, rather than placing an apical retrograde filling, a retrograde endodontic treatment of the entire canal should be preferred, if it is feasible.

Comparison of the sealing ability of four obturation techniques

This study compared the apical seal produced by four obturation techniques. The Canal Finder system was compared with lateral condensation, the Ultrafil system, and the sectional warm gutta-percha techniques. Forty-two anterior single-rooted teeth were instrumented. Ten teeth were not obturated and served as positive and negative controls. The apical seal was tested for leakage with 0.25% methylene blue dye. The teeth were shaved horizontally and dye penetration was measured with a Boley gauge. Results revealed there was no statistically significant difference among the four obturation techniques.