Case series: tooth retention 5 years after irretrievable separation of LightSpeedLSX instruments.

INTRODUCTION: Of 3,216 root canals treated endodontically at the Creighton University School of Dentistry from September 1, 2005, to August 31, 2007, with LightSpeedLSX instruments (LightSpeed Technology, Inc, San Antonio, TX), there were 12 cases of irretrievable instrument separation. More than 5 years after the separations, an attempt was made to contact the patients and assess for healing and tooth retention. METHODS: Third- and fourth-year dental students performed root canal procedures according to protocol from September 1, 2005, to August 31, 2007. A database was collected during the 24-month period recording cases with irretrievable LightspeedLSX separation. Efforts were made from July 2011 to December 2011 to contact the 12 patients for endodontic follow-up. Clinical and radiographic evaluations of healing were performed. RESULTS: Of the 12 patients with irretrievable separations, 8 patients were contacted and 5 returned to Creighton University School of Dentistry for follow-up. All 8 contacted patients confirmed the presence of the root canal-treated tooth in question, and the teeth of the 5 evaluated patients were determined to be asymptomatic and functional. Radiographic analysis resulted in 2 teeth being classified as complete healing, 2 as uncertain healing, and 1 as no healing. CONCLUSIONS: The 100% tooth retention rate and the lack of symptoms in 8 contacted (5 evaluated) patients 5 years after treatment suggests that long-term retention and functionality can occur after irretrievable instrument separation. Although tooth retention and functionality are desirable outcomes, radiographic findings may be indicative of inadequate periapical healing, thus requiring the clinician to evaluate whether additional treatment is necessary.

Repair of a large furcation perforation: a four-year follow-up.

This case report describes the management of a large furcation perforation in a maxillary first molar. Although the majority of the pulpal floor was destroyed and the mesiobuccal root was damaged, an attempt was made to repair the defect and restore the tooth. An absorbable gelatin sponge matrix was placed, and the defect was repaired with gray ProRoot mineral trioxide aggregate. Subsequently the endodontic treatment was completed; the tooth was restored and was later used as a fixed partial denture abutment. A 55-month recall showed no evidence of periodontal breakdown, no symptoms, and complete healing of all periradicular lesions.

Effects of pH and mixing agents on the temporal setting of tooth-colored and gray mineral trioxide aggregate.

The purpose of this study was to test the compressive strength of white mineral trioxide aggregate (WMTA) and gray mineral trioxide aggregate (GMTA) when mixed with sterile water or local anesthetic and exposed to an acidic environment. A total of 248 samples of WMTA and GMTA were mixed and placed in phosphate-buffered saline (PBS), at pH 5.0 or 7.4, for a period of 7 or 28 days. When WMTA and GMTA were mixed with local anesthetic, the following were observed: 1) pH 5.0 caused a significant decrease in compressive strength (p<0.0001); 2) WMTA was significantly stronger than GMTA (p<0.0001); and 3) more time in PBS (total 28 days) caused a significant decrease in compressive strength (p<0.001). There were no consistent differences in compressive strength for WMTA or GMTA when mixed with sterile water. Variability of results suggests both types of MTA be mixed with sterile water in acidic and neutral environments.

The anti-microbial effect against enterococcus faecalis and the compressive strength of two types of mineral trioxide aggregate mixed with sterile water or 2% chlorhexidine liquid.

The purpose of this in vitro study was 2-fold: First, to compare the antimicrobial effect of gray and tooth-colored mineral trioxide aggregate (MTA) when mixed with sterile water or 2% chlorhexidine. Second, to compare the compressive strengths of the MTA/chlorhexidine versus MTA/sterile water samples. The antimicrobial effect test was accomplished by placing freshly mixed MTA samples on agar plates inoculated with Enterococcus faecalis and comparing the zones of inhibition at 24 hours. In the compressive strength test, MTA pellets were allowed to set for 72 hours and then compressed to fracture by using an Instron testing machine. Values were recorded and compared. In the antimicrobial effect experiment, the zones of inhibition were significantly larger for samples mixed with 2% chlorhexidine. In the compressive strength study, statistical evaluation showed no significance due to variability. However, data revealed that MTA mixed with sterile water always had higher compressive strengths than MTA mixed with chlorhexidine.

Fracture resistance of simulated immature teeth filled with resilon, gutta-percha, or composite.

The purpose of this study was to evaluate the fracture resistance gained by filling root canals of simulated immature teeth with either Resilon, gutta-percha, a self-curing flowable composite resin (BisFil 2B), or a self-curing hybrid composite resin (BisFil II). Seventy-two sheep incisors were divided into six groups of 12 teeth each. Negative controls received no treatment. Teeth in all other groups were prepared until a size 120 LightSpeed LSX instrument could be passed out the apex. After apical placement of a mineral trioxide aggregate (MTA) barrier, the canals were filled with their respective test material to the facial CEJ. The positive control canals were left unfilled. The access openings (including positive controls) were restored with BisFil II. Each root was horizontally fractured through the test material using an Instron. The mean peak loads to fracture were recorded. The hybrid composite resin (BisFil II) was the only material significantly more fracture resistant than positive controls (p < 0.017).

Effect of blood contamination on retention characteristics of MTA when mixed with different liquids.

Simulated furcation perforations were repaired with and without blood contamination utilizing tooth-colored mineral trioxide aggregrate (MTA) mixed with either MTA liquid (sterile water), lidocaine, or saline. Samples underwent Instron testing at either 24 or 72 hours and at 7 days. Data were analyzed using a 3-way ANOVA and post-hoc testing using Turkey's true test for significance. All of the 72-hour samples displayed significantly greater resistance to displacement than the 24-hour samples. All of the 7-day samples displayed significantly greater resistance to displacement than the 24-hour and 72-hour samples. Non-contaminated samples displayed significantly greater resistance to displacement than their blood-contaminated counterparts at 7 days. Non-contaminated samples mixed with sterile water, lidocaine, or saline performed similarly at all time periods. Allowing tooth-colored MTA to set undisturbed for 72 hours or longer prior to placement of a coronal restoration may decrease the chance of MTA displacement in furcation perforation repairs.

Contamination of tooth-colored mineral trioxide aggregate used as a root-end filling material: a bacterial leakage study.

This experiment investigated the ability of tooth-colored mineral trioxide aggregate (MTA) to maintain an apical seal in the presence of bacteria when contaminated with blood, saline or saliva. Ninety extracted human teeth with single canals were randomly placed into six groups of 15. Canals were prepared to size 50. The apical 3 mm of each root was removed and 3 mm root-end preparations were made with a #329 bur. Root-end preparations in groups 1 through 3 were filled with MTA after contamination with blood, saline, or saliva, respectively. In group 4, uncontaminated root-end preparations were filled with MTA. Groups 5 and 6 served as negative and positive controls. A tube/tooth assembly was utilized to suspend each root end in Trypticase Soy Broth (TSB). The access chambers were filled with Staphylococcus epidermidis. Positive growth over thirty days was demonstrated by turbidity of the TSB. Vitek analysis was used to confirm the presence of S. epidermidis in the positive samples. Data evaluation consisted of a chi(2) analysis (p < 0.05). Although all experimental groups demonstrated leakage, tooth-colored MTA contaminated with saliva (group 3) leaked significantly more than the uncontaminated tooth-colored MTA (group 4) (p = 0.028).

Reinforcement of immature roots with a new resin filling material.

The purpose of this study was to compare the reinforcement and strengthening ability of Resilon, gutta-percha, and a self-curing composite resin (Bisfil 2B) in endodontically treated roots of immature teeth. Sixty single rooted teeth were divided into five groups of 12 teeth each. Teeth in all groups except the negative controls were prepared with a #5 Peeso (1.5 mm) through the apex (simulating immature roots) and root ends were filled with a 4 mm barrier of MTA. After smear layer removal, canals in the three experimental groups were backfilled with gutta-percha, Resilon, or Bisfil 2B. The remaining canal space in the positive control group was left unfilled. Negative controls received no treatment. A horizontal fracture was created in the root of each specimen using an Instron and the mean peak loads to fracture were recorded. ANOVA revealed no significant difference between any of the treatment groups. Based on the results of this study, canal wall reinforcement of teeth with a canal diameter of 1.5 mm or less may not be necessary.

Cyclic fatigue of three types of rotary nickel-titanium files in a dynamic model.

The cyclic fatigue resistance of three types of nickel-titanium rotary files was compared in a model using reciprocating axial movement. The influence of file size and taper was also investigated and fracture patterns were examined under SEM. The 10 experimental groups consisted of ProFiles, K3s, and RaCe files, size 25 in .04 and .06 tapers, as well as ProFiles and K3s, size 40 in .04 and .06 tapers. Each file was rotated freely at 300 rpm inside a stainless steel tube with a 60 degree and 5 mm radius of curvature. A continuous 3 mm oscillating axial motion was applied at 1 cycle per second by attaching an electric dental handpiece to the most inferior load cell of an Instron machine using a custom-made jig. The number of rotations to failure was determined and analyzed using analysis of variance and Tukey's post hoc tests. Overall, K3 25/.04 files were significantly more resistant to cyclic fatigue compared to any other group in this study. In the 25/.04 category, K3s were significantly more resistant to failure than ProFiles and RaCe files. Also in the same category, ProFiles significantly outlasted RaCe files. In the 25/.06 group, K3s and ProFiles were significantly more resistant to failure than RaCe files, but K3s were not significantly different than ProFiles. In the 40/.04 and 40/.06 groups, K3s were significantly more resistant to cyclic fatigue than ProFiles. SEM observations demonstrated mostly a ductile mode of fracture. The results suggest that different cross-sectional designs, diameters, and tapers all contribute to a nickel-titanium instrument's vulnerability to cyclic failure.

Enterococcus faecalis: its role in root canal treatment failure and current concepts in retreatment.

Enterococcus faecalis is a microorganism commonly detected in asymptomatic, persistent endodontic infections. Its prevalence in such infections ranges from 24% to 77%. This finding can be explained by various survival and virulence factors possessed by E. faecalis, including its ability to compete with other microorganisms, invade dentinal tubules, and resist nutritional deprivation. Use of good aseptic technique, increased apical preparation sizes, and inclusion of 2% chlorhexidine in combination with sodium hypochlorite are currently the most effective methods to combat E. faecalis within the root canal systems of teeth. In the changing face of dental care, continued research on E. faecalis and its elimination from the dental apparatus may well define the future of the endodontic specialty.