Risk Factors and Prevalence of Occupational Musculoskeletal Pain among Endodontists in the United States.

INTRODUCTION: A musculoskeletal disorder (MSD) of pain, weakness, numbness, or paresthesia is a common issue for dental health care providers. The aims of this study were to (1) identify the prevalence of MSDs among endodontists in the United States, (2) to identify risk factors of MSDs among United States endodontists, and (3) to compare these findings with other published findings for dental providers. METHODS: A 24-question survey regarding the demographics, potential risk factors, and prevalence of MSDs was formulated and distributed to 5394 members of the American Association of Endodontists. Data were then analyzed using descriptive statistics and chi-square analysis to find significance at α = 0.05. RESULTS: Six hundred twenty participants responded to the survey for an overall response rate of 12%. Of the submitted surveys, 527 of them confirmed to be endodontists practicing in the United States, and all results were derived from those 527 surveys. Seventy-four percent of respondents reported having experienced MSDs in the last 12 months, and 88% reported having experienced at least 1 MSD thus far during their career. Eighty-five percent of female participants reported an MSD within the past 12 months compared with 70% of males. CONCLUSIONS: MSDs have a high prevalence among endodontists in the United States. The neck and lower back were the areas of highest MSD prevalence. Female sex and the frequent adoption of awkward postures were factors associated with significantly higher rates of reported MSDs in the last 12 months.

Comparison of IL-1ß, TNF-α, hBD-2, and hBD-3 Expression in the Dental Pulp of Smokers Versus Nonsmokers.

INTRODUCTION: To date, the endodontic literature lacks research on the effect of smoking on cytokine and defensin expression in the dental pulp. Therefore, the aim of this study was to investigate the expression of interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, human beta defensin (hBD)-2 and hBD-3 in the dental pulp of smokers and compare them with nonsmokers. We hypothesized that cytokine and defensin expression would be reduced in smokers as compared with nonsmokers. METHODS: Thirty-two smokers and 37 nonsmokers with endodontic pulpal diagnoses of normal, symptomatic irreversible pulpitis and asymptomatic irreversible pulpitis were included in this cross-sectional study. Samples from pulp chambers were collected and stored in phosphate-buffered saline at -80°C. Luminex was used to measure IL-1ß and TNF-α levels. The levels of hBD-2 and hBD-3 were measured using enzyme-linked immunosorbent assay. Marker levels were normalized to protein concentrations and data were analyzed using Kruskal-Wallis test, Mann-Whitney U test, and 2-way analysis of variance (α = 0.05). RESULTS: Pulpal concentrations of TNF-α and hBD-2 were significantly lower among smokers (P < .01), whereas no significant difference was observed for IL-1ß, or hBD-3. Two-way analysis of covariance revealed that smoking status (P < .001), not endodontic diagnosis (pulpal status), significantly affected TNF-α and hBD-2 levels. CONCLUSIONS: This study reported that smokers are immunologically deficient in TNF-α and hBD-2, suggesting that dental pulps of smokers possess limited defense mechanisms, affecting their endodontic prognosis and indicating a cause for their reported inferior outcome.

Introduction of implants into postdoctoral endodontic residency programs.

The purpose of this study was to survey the directors of postdoctoral endodontic programs in the United States to ascertain their attitudes and approaches regarding incorporation of implants into the endodontic curriculum. We hypothesized that program directors would agree that implant training should be incorporated into the endodontic curriculum. We also hypothesized that they would all prefer apical surgeries and retreatment over implants when plausible. A twenty-item online survey was emailed to all fifty-two postdoctoral endodontic program directors in the United States. A 100 percent response was received. The results showed that 78.6 percent agreed that implant training should be incorporated, 85.7 percent preferred the didactic approach, and 42.9 percent preferred clinical implant training. One hundred percent preferred apical surgeries and retreatment over implants when plausible, and 53.8 percent did not prefer implants over endodontic treatment for teeth with a questionable prognosis. This survey indicates that implant training has been incorporated into postdoctoral endodontic programs and that the Commission on Dental Accreditation standards are being met. The trend may be to become more hands-on in the future if program directors believe there is a need to provide training in actual placement of implants.

Molecular analysis of persistent periradicular lesions and root ends reveals a diverse microbial profile.

INTRODUCTION: The microbial etiology of periradicular lesions is recognized; however, the bacterial profile of these lesions is not well elucidated. The purpose of this study was to determine the frequency of bacterial colonization in these lesions and to characterize the bacterial community present in root ends and periradicular lesions. METHODS: Thirty-four adult patients who presented for apicoectomy of persistent periradicular lesions after endodontic therapy were selected for the study and samples of periradicular tissue and resected root ends collected. Total bacterial levels were estimated for 34 paired periradicular lesions and root ends using real-time polymerase chain reaction with universal bacterial primers. Sixteen pairs of these samples were analyzed using ribosomal 16S cloning and sequencing for bacterial identification. RESULTS: Bacteria were detected more consistently and at higher levels in root ends. Periradicular lesions exhibited a diverse microbial profile with many uncultivated phylotypes. Enterococcus faecalis and Burkholderia cepacia predominated in both samples. Campylobacter gracilis and Streptococcus gordonii were associated with root ends, whereas Atopobium rimae, Peptostreptococcus micros, Streptococcus genomospecies C8, Dialister sp E2_20 E1, and Eubacterium strain A35MT were associated with periradicular lesions. CONCLUSIONS: Persistent periradicular lesions are polymicrobial infections with many as-yet-uncultivated and unknown bacterial species. The bacterial load and microbial profile of root ends is significantly different from the soft-tissue lesion, indicating the presence of diverse bacterial populations in these tissues.

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 2--Bacterial penetration.

OBJECTIVE: To compare the relative penetration of Prevotella melaninogenica and Enterococcus faecalis through 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial penetration when compared to Lambone and Atrisorb. METHOD AND MATERIALS: Centrifuge tubes containing trypticase soy broth were sealed with circular sections of membranes and placed in test tubes containing culture media. The bacterial penetration was assessed by passage of bacteria from the outer tube culture media to the inner centrifuge tube media through the membrane. After incubation for 4 and 48 hours, the media from the outer and inner tubes were compared for bacterial count. RESULTS: P melaninogenica exhibited 91% penetration for Lambone in 2 days, while OsseoQuest displayed 87% penetration with E faecalis in the same time. Atrisorb displayed a minimal penetration with both bacteria (2%). CONCLUSION: Atrisorb displayed the least bacterial penetration, which may be attributed to membrane structure, chemical configuration, hydrophobicity, and porosity of tested membranes.

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 1--Bacterial adherence.

OBJECTIVE: To compare the adherence of Prevotella melaninogenica and Enterococcus faecalis to 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial adherence compared to Lambone and Atrisorb. METHOD AND MATERIALS: The barriers were suspended in trypticase soy broth containing an inoculum of either P melaninogenica or E faecalis. The samples were incubated under appropriate conditions for 6, 24, and 48 hours. Following incubation, each membrane was mixed in fresh media in a vortex machine to dislodge adherent bacteria. The vortexed media was quantitatively assessed using serial dilutions for viable cell count. RESULTS: E faecalis exhibited higher adherence compared to P melaninogenica with time. Of the membranes tested, Lambone displayed the least bacterial adherence. CONCLUSION: An analysis of the results indicated that bacterial adherence was time-dependent for all membranes. Membrane structure, chemical configuration, hydrophobicity, and bacterial cell surface structure were suggested as factors contributing to variance in bacterial adherence.

Intracanal assessment of mineral trioxide aggregate setting and sealing properties.

This study sought to assess setting time and sealing properties of intracanal mineral trioxide aggregate (MTA). Eighty-three extracted single-rooted human teeth were decoronated and instrumented using the crown-down technique. The apical 3.0 mm of each tooth was resected. After MTA was placed, the coronal openings of the canals were sealed with moist cotton pellets. Root samples were divided into three groups according to setting time periods of four hours, two days, or one week. Within each group, 15 samples were kept in wet gauze to provide a moist apical environment (WA) while the remaining 10 were kept in a dry apical environment (DA). After respective incubation periods, 20 samples per group (10 WA, 10 DA) were mounted in an apical broth turbidity determination chamber and incubated for 30 days. The remaining five teeth per group (WA-h) were sectioned into 3.0 mm slices and compared for MTA setting hardness using the Shore-D Hardness test. Remaining teeth served as negative and positive controls. Each sample was inoculated coronally with Enterococcus faecalis and checked daily for turbidity in apical broth. Microbial leakage was reduced significantly as setting time increased from four hours to two days or one week. There was no significant reduction in leakage when setting time was increased from two days to one week. Over the first 20 days, the DA samples showed a higher rate of leakage compared to the WA samples. The Shore-D hardness test correlated with leakage results; 93% of total setting hardness was reported at two days and one week compared to only 75% for the four-hour group. Results suggest that apical moisture may affect MTA setting time or sealing ability initially and that intracanal MTA may take up to two days to set completely.

A correlation study of occlusal and pulp chamber anatomy: the maxillary first molar.

The success of endodontic therapy is based on a number of criteria, particularly the conservation of tooth structure. This principle requires a systematic approach to pulp chamber access. By correlating the occlusal anatomy with the location of the root canal orifice, a dentist may find a number of guidelines for improving access design. In this in vitro study, the authors evaluated 29 human maxillary first molars. Digital radiographs and digital occlusal photographs were taken of each specimen before and after decoronation at the cementoenamel junction (CEJ). The three images were superimposed on one another and evaluated for occlusal and pulpal patterns. The thickness of the pulp chamber walls of the CEJ varied, based on the circumference of individual teeth. In addition, the canal orifices at the pulp chamber floor exhibited a consistent pattern relative to the cusp tips, which may assist in access design.

A correlation study of occlusal and pulp chamber anatomy: the mandibular first molar.

Many parameters must be addressed for endodontic therapy to succeed. Because conservation of tooth structure is vital, the pulp chamber and root canal orifices should be located by using a method that is consistent yet accurate. The correlation of occlusal anatomy with the locations of the root canal orifice may aid dentists with access design. This study sought to determine if a correlation existed between occlusal surface anatomy, pulp chamber location, and root canal orifice location. This in vitro study utilized 21 human mandibular first molars. For each specimen, amalgam restorations were placed in the respective cusp tips, with gutta-percha placed in each canal at the level of the furcation. The authors made digital radiographs and occlusal photographs of each complete specimen. The samples were sectioned horizontally at the level of the cementoenamel junction (CEJ). Using a digital software program, the radiographs were superimposed with the digital photographs and correlations of pulp chamber to locate the canal orifice and occlusal surface anatomy. The authors found that the pulp chamber of the mandibular first molar lies more lingual at the level of the CEJ. In addition, the orifices were consistent in their location relative to cusp tip anatomy, a discovery that may assist dentists with the access design.

The role of apical size determination and enlargement in the reduction of intracanal bacteria.

The master apical preparation size in root canal therapy is debatable despite considerable research. The present study compared file sizes that bind at the apex before and during crown-down preparation and assessed the relation between apical size and extent of intracanal bacterial load. There were 100 single-rooted teeth biomechanically prepared after inoculation with Enterococcus faecalis. Canals were preflared, and apical size was ascertained by the first file to bind (FAB) at the working length (WL). During crown-down preparation, the first crown-down file to reach the apex during instrumentation was noted (CDF). Teeth were then divided into three master apical file size groups of CDF + 1, CDF + 2, and CDF + 3. Positive controls were inoculated postinstrumentation, whereas negative controls were instrumented without inoculation (n = 5). The samples were then cultured for intracanal bacterial counts. Fifteen samples and four controls were analyzed under SEM. The data were analyzed using ANOVA, Student's t-test, and chi(2) tests. The CDF was demonstrated to be an average of four file sizes larger than the FAB (p < 0.05). There was a significant increase in the number of samples with negative cultures from CDF + 1 to CDF + 3. SEM observation revealed bacteria on dentinal walls and in tubules even in most negative canal cultures.

An analysis of current analgesic preferences for endodontic pain management.

A descriptive, cross sectional survey was developed to determine the preferences of endodontists when prescribing analgesics. Eleven clinical scenarios describing common endodontic diagnoses or procedures with specified severity of pain were provided. A survey was sent to 310 AAE members and 63 responded, providing a 20% response rate. Respondents were given various choices for analgesic prescription including various dosages of ibuprofen or acetaminophen (APAP), or combination narcotic medications. Data were analyzed by chi2 tests. Non-narcotics were preferred over narcotics for all clinical situations. Significantly more respondents selected ibuprofen 600 mg (4x a day) regardless of the severity of preoperative or postoperative pain (p<0.001). Educators and board-certified AAE members were less likely than nonboard certified AAE members to manage their patient's perceived severe pain with narcotic analgesics.

Electric pulp tester conductance through various interface media.

A conducting media is necessary when using an electric pulp tester (EPT). The objective of this study was to observe differences in conductance through various media. We hypothesized that variations in current conductance through different media exist. The pulp chamber of a freshly extracted premolar was exposed, and the cathode of a voltmeter was inserted into the pulpal tissue. The anode was coupled to the EPT handpiece. The measurement taken during dry (no interface media) EPT tip-to-tooth contact was 0 V, which served as negative control. EPT tip directly touching the cathode measured 3.9V and served as positive control. A number of media readily available in the dental office were tested. Data was analyzed using single factor ANOVA. Listerine (3.3) conducted the most voltage (p<0.5). Of nonliquids, K-Y Brand UltraGel and Crest Baking Soda & Peroxide Whitening Tartar Control toothpaste recorded significantly (p<0.05) higher voltage readings (1.4 V).

Endodontic treatment in an American Indian population: a 10-year retrospective study.

An epidemiological study of a regional population of Native Americans receiving treatment from 1991 to 2000 (n = 5460) was conducted via electronic survey. The objectives were to identify factors affecting the retention of endodontically treated teeth and to determine frequencies of endodontic care. Multiple factors were assessed. Analyses utilized chi(2) and frequency tests. The results indicated that endodontists tend to complete most posterior teeth and retreatment cases, while generalists tended to complete anterior teeth, primary endodontic therapy, and to restore immediately. Patients with multiple systemic diseases (p = 0.0225) and diabetes (p < 0.0001) experienced decreased retention of endodontically treated teeth and increased retreatment (p = 0.0109) by endodontists. Patients treated by general dentists experienced increased retention for female patients (p = 0.0066), immediate restoration of the treated tooth (p = 0.0212), and decreased retention with a history of hypertension (p = 0.0036) and diabetes (p = 0.0033). This study suggests that diabetes and/or hypertension, delayed or no restoration, and increasing age, may all contribute to decreased retention of endodontically treated teeth, but that immediate postendodontic restoration may enhance retention. In the early era, very few cases of molar endodontics were completed, and one could infer that there were greater numbers of posterior teeth extracted because of this fact. This demonstrates how a combination of providers can provide a broader range of clinical endodontic services, supporting an Indian Health Service goal of providing the highest level of oral health care possible.

Evaluation of cutting efficiency of ultrasonic tips used in orthograde endodontic treatment.

The purpose of the present study was to evaluate the cutting efficiency of the three different ultrasonic tips for orthograde endodontic treatment: stainless steel, zirconium nitride-coated, and diamond-coated tips. An ultrasonic handpiece was mounted on a custom-made automated balance, and each tip repeatedly penetrated dental stone blocks to a depth of 3 mm for 10 times. The amount of time taken to penetrate 3 mm of stone was measured. The diamond-coated tips showed significantly greater cutting efficiency than either stainless steel tips or zirconium-nitride coated tips. The stainless steel tips showed initial better cutting efficiency, but over time , there is no significant difference between the cutting efficiency of the stainless steel tips and the zirconium nitride coated tips. The diamond coated tips were the only group that showed breakage in this study.

An in vitro assessment of iodoform gutta-percha.

The purpose of this study was to test the ability of a commercially available iodoform gutta-percha, to delay infiltration of Enterococcus faecalis using a microleakage model. Seventy extracted single-rooted teeth were decoronated and biomechanically prepared using hand and rotary instruments. Thirty roots were obturated laterally with iodoform gutta-percha and another 30 with regular gutta-percha. Both groups were suspended in sterile BHI broth. An inoculum of E. faecalis suspension was placed at the coronal end of each root, incubated and replenished daily. The apical broth was observed for turbidity, indicating bacterial microleakage. Samples were observed for 32 days, and data was analyzed to compare microleakage between the two groups. The results showed no significant difference between the iodoform and regular gutta-percha samples in delaying microleakage of E. faecalis (p > 0.05).

Effectiveness of selected materials against Enterococcus faecalis: part 3. The antibacterial effect of calcium hydroxide and chlorhexidine on Enterococcus faecalis.

It has been found that Enterococcus faecalis is most commonly isolated in failed endodontic treatment. Irrigation with chlorhexidine gluconate has been suggested based on its antimicrobial effect and substantivity. Calcium hydroxide also is an effective antimicrobial agent because of its high alkalinity. The purpose of this study was to test the individual and combined effect of calcium hydroxide and chlorhexidine against E. faecalis. The agar-diffusion test was performed on Mueller-Hinton plates. Paper disks were impregnated with: (a) CaOH powder with sterile water; (b) Pulpdent; (c) 0.12% Peridex; (d) CaOH powder with Peridex; and (e) Pulpdent with Peridex. Ampicillin served as a control. The plates were incubated at 37 degrees C for 72 h. Peridex showed significantly larger zones of inhibition compared with CaOH. No statistically significant difference was found between Peridex and the combination of CaOH and Peridex.

Antimicrobial activity of endodontic sealers on Enterococcus faecalis.

Enterococcus faecalis has been shown to be highly resistant once established in the root canal system and may play an important role in endodontic failures. The purpose of this study was to evaluate the antimicrobial activity of four root canal sealers on E. faecalis. Seventeen blood-agar plates were inoculated with E. faecalis using the Lawn technique. Five discs were placed on each plate, four with sealers--Sealapex, Roth 811, Kerr EWT, and AH-Plus--and an ampicillin disc as the control. The plates were incubated at 37 degrees C. The zones of inhibition were measured at 24 and 48 h. Analysis using a one-way ANOVA and Tukey test showed a statistically significance difference (p < 0.05) between all four groups of sealers. Roth 811 showed the largest zone of inhibition (1.1 mm), followed by Sealapex (0.8 mm) and Kerr EWT (0.5 mm), whereas AH-Plus had no antimicrobial activity. There was no difference in the zones of inhibition between the 24- and 48-h time periods.

Effectiveness of stannous fluoride and calcium hydroxide against Enterococcus faecalis.

The objective of this study was to evaluate the antimicrobial activity of stannous fluoride, calcium hydroxide, or the two in combination against Enterococcus faecalis. Fifteen Mueller-Hinton agar plates were used to conduct a disc diffusion susceptibility test. The plates were inoculated with E. faecalis. The groups tested were: (a) stannous fluoride (Stanimax); (b) calcium hydroxide; and (c) a combination of stannous fluoride and calcium hydroxide. Three filter paper discs, each soaked with one of the groups, were placed along with an antibiotic control (ampicillin) on each agar plate. The plates were then incubated at 37 degrees C. The zones of inhibition were measured at 24 and 48 h. One-way ANOVA revealed a statistically significant difference (p < 0.05) between the three groups. Stannous fluoride displayed the widest zone (1.7 mm), followed by the combination of stannous fluoride and calcium hydroxide (1.1 mm), whereas calcium hydroxide by itself displayed a minimal zone of inhibition (0.05 mm).

An in vitro evaluation of the antibacterial properties of barriers used in guided tissue regeneration.

The inhibition of growth of Prevotella nigrescens and Enterococcus faecalis by three barriers membrane, (a) polylactic acid (Atrisorb), (b) laminar bone, and (c) calcium sulfate, was compared using an agar diffusion test. The first group of 20 plates were inoculated with P. nigrescens in a prereduced anaerobically-sterilized brain-heart infusion broth, while the second group of 20 plates were inoculated with E. faecalis in a brain-heart infusion broth. On each plate, a 5.0-mm section of each barrier was placed such that every plate had all three barriers. The plates in the P. nigrescens group were incubated in an anaerobic chamber for 7 days. The plates in the E. faecalis group were incubated at 37 degrees C for 2 days. No zones of inhibition were observed with laminar bone or calcium sulfate. Zones of inhibition were observed with the Atrisorb barrier membrane in both groups. The zone of inhibition of P. nigrescens was significantly greater than the zone of inhibition of E. faecalis. The hydrophobicity of Atrisorb and its N-methyl-2-pyrolidine component were suggested as the sources of its antibacterial activity.