16S Ribosomal RNA Gene Sequencing to Evaluate the Effects of 6 Commonly Prescribed Antibiotics.

INTRODUCTION: The rapid antibiotic sensitivity test (RAST) is a novel in-office culture and sensitivity system for endodontic infections. The purpose of this research was to validate the RAST system as a viable, in-office alternative to antibiotic sensitivity testing using turbidity to determine antibiotic sensitivities of endodontic infections. METHODS: Aspirates were taken from the root canals of 9 necrotic human teeth at the initiation of root canal therapy. These samples were cultured in the RAST medium, and antibiotic sensitivity to 6 antibiotics was tested. Further analysis was performed using 16S ribosomal RNA (rRNA) gene sequencing. RESULTS: Thirty-one bacterial phyla were identified as well as 2 phyla of the kingdom Archaea. Augmentin (Dr. Reddy's Laboratories Ltd, Hyderabad, India) and ampicillin performed identically at 24 hours, inhibiting turbidity in 100% of the samples. At 48 hours in anaerobic conditions, Augmentin outperformed ampicillin by 13%. Ciprofloxacin was the least efficacious antibiotic. At 48 hours, only 22% of anaerobic ciprofloxacin cultures affectively inhibited bacterial growth. CONCLUSIONS: The RAST medium is a viable in-office alternative to antibiotic susceptibility testing in an off-site laboratory. It is able to support the growth of a wide variety of microorganisms in both aerobic and anaerobic environments, and, in combination with 16S rRNA gene sequencing, it led to the identification of a new archaebacterial phylum, Crenarchaeota, as part of the endodontic infection microbiome.

Techniques and materials used by general dentists during endodontic treatment procedures: Findings from The National Dental Practice-Based Research Network.

BACKGROUND: Little is known about which materials and techniques general dentists (GDs) use during endodontic procedures. The objectives were to quantify GDs' use of specific endodontic tools, quantify inappropriate use, and ascertain whether inappropriate use is associated with GDs' practice characteristics. METHODS: GDs in The National Dental Practice-Based Research Network reported in a questionnaire materials and techniques they use during endodontic procedures. RESULTS: Among eligible GDs, 1,490 (87%) participated. Most (93%; n = 1,383) used sodium hypochlorite to irrigate. The most commonly used sealers were zinc oxide eugenol (43%) and resin (40%), followed by calcium hydroxide (26%). Most (62%; n = 920) used a compaction obturation technique; 36% (n = 534) used a carrier-based method. Most (96%; n = 1,423) used gutta-percha as a filler; 5% used paste fillers. Few used irrigants (n = 46), techniques (n = 49), or fillers (n = 10) that investigators classified as inappropriate. CONCLUSIONS: GDs use a broad range of endodontic techniques and materials, often adapting to newer technologies as they become available. Few GDs use tools that the investigators classified as inappropriate. PRACTICAL IMPLICATIONS: GDs use many types of endodontic techniques and materials, but only a small percentage of them are inappropriate.

Discordance between presumed standard of care and actual clinical practice: the example of rubber dam use during root canal treatment in the National Dental Practice-Based Research Network.

OBJECTIVES: Use of a rubber dam during root canal treatment is considered the standard of care because it enhances patient safety and optimises the odds of successful treatment. Nonetheless, not all dentists use a rubber dam, creating disconnect between presumed standard of care and what is actually done in clinical practice. Little is known about dentists' attitudes towards use of the rubber dam in their practices. The objectives were to: (1) quantify these attitudes and (2) test the hypothesis that specific attitudes are significantly associated with rubber dam use. SETTING: National Dental Practice-Based Research Network (NationalDentalPBRN.org). PARTICIPANTS: 1490 network dentists. OUTCOME MEASURES: Dentists completed a questionnaire about their attitudes towards rubber dam use during root canal treatment. Three attitude scales comprised 33 items that used a 5-point ordinal scale to measure beliefs about effectiveness, inconvenience, ease of placement, comparison to other isolation techniques and patient factors. Factor analysis, cluster analysis and multivariable logistic regression analysed the relationship between attitudes and rubber dam use. RESULTS: All items had responses at each point on the 5-point scale, with an overall pattern of substantial variation across dentists. Five attitudinal factors (rubber dam effectiveness; inconvenient/time-consuming; ease of placement; effectiveness compared to Isolite; patient factors) and 4 clusters of practitioners were identified. Each factor and cluster was independently and strongly associated with rubber dam use. CONCLUSIONS: General dentists have substantial variation in attitudes about rubber dam use. Beliefs that rubber dam use is not effective, inconvenient, time-consuming, not easy to place or affected by patient factors, were independently and significantly associated with lower rubber dam use. These attitudes explain why there is substantial discordance between presumed standard of care and actual practice.

Evaluation of ciprofloxacin and metronidazole encapsulated biomimetic nanomatrix gel on Enterococcus faecalis and Treponema denticola.

BACKGROUND: A triple antibiotic mixture (ciprofloxacin; CF, metronidazole; MN, and minocycline; MC) has been used for dental root canal medicaments in pulp regeneration therapy. However, tooth discolorations, cervical root fractures, and inadequate pulp-dentin formation have been reported due to the triple antibiotic regimen. Therefore, an antibiotic encapsulated biomimetic nanomatrix gel was developed to minimize the clinical limitations and maximize a natural healing process in root canal infections. In this study, minimal bacterial concentrations (MBC) of the selected antibiotics (CF and MN) were tested in 14 representative endodontic bacterial species. Then MBC of each CF and MN were separately encapsulated within the injectable self-assembled biomimetic nanomatrix gel to evaluate antibacterial level on Enterococcus faecalis and Treponema denticola. RESULTS: Antibiotic concentrations lower than 0.2 µg/mL of CF and MN demonstrated antibacterial activity on the 14 endodontic species. Furthermore, 6 different concentrations of CF and MN separately encapsulated with the injectable self-assembled biomimetic nanomatrix gel demonstrated antibacterial activity on Enterococcus faecalis and Treponema denticola at the lowest tested concentration of 0.0625 µg/mL. CONCLUSIONS: These results suggest that each CF and MN encapsulated within the injectable self-assembled biomimetic nanomatrix gel demonstrated antibacterial effects, which could be effective for the root canal disinfection while eliminating MC. In the long term, the antibiotic encapsulated injectable self-assembled biomimetic nanomatrix gel can provide a multifunctional antibiotic delivery method with potential root regeneration. Further studies are currently underway to evaluate the effects of combined CF and MN encapsulated within the injectable self-assembled biomimetic nanomatrix gel on clinical samples.

General Dentists' Use of Isolation Techniques during Root Canal Treatment: From the National Dental Practice-based Research Network.

INTRODUCTION: A preliminary study done by a National Dental Practice-Based Research Network precursor observed that 44% of general dentists (GDs) reported always using a rubber dam (RD) during root canal treatment (RCT). This full-scale study quantified the use of all isolation techniques, including RD use. METHODS: Network practitioners completed a questionnaire about isolation techniques used during RCT. Network enrollment questionnaire data provided practitioner characteristics. RESULTS: One thousand four hundred ninety of 1716 eligible GDs participated (87%); 697 (47%) reported always using an RD. This percentage varied by tooth type. These GDs were more likely to always use an RD, do not own a private practice, perform less than 10 RCTs/month, and have postgraduate training. CONCLUSIONS: Most GDs do not use an RD all the time. Ironically, RDs are used more frequently by GDs who do not perform molar RCT. RD use varies with tooth type and certain dentist, practice, and patient characteristics.

A small molecule, odanacatib, inhibits inflammation and bone loss caused by endodontic disease.

Periapical disease, an inflammatory disease mainly caused by dental caries, is one of the most prevalent infectious diseases of humans, affecting both children and adults. The infection travels through the root, leading to inflammation, bone destruction, and severe pain for the patient. Therefore, the development of a new class of anti-periapical disease therapies is necessary and critical for treatment and prevention. A small molecule, odanacatib (ODN), which is a cathepsin K (Ctsk) inhibitor, was investigated to determine its ability to treat this disease in a mouse model of periapical disease. While Ctsk was originally found in osteoclasts as an osteoclast-specific lysosomal protease, we were surprised to find that ODN can suppress the bacterium-induced immune response as well as bone destruction in the lesion area. X rays and microcomputed tomography (micro-CT) showed that ODN treatment had significant bone protection effects at different time points. Immunohistochemical and immunofluorescent staining show that ODN treatment dramatically decreased F4/80+ macrophages and CD3+ T cells in the lesion areas 42 days after infection. Consistent with these findings, quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) analysis showed low levels of proinflammatory mRNAs (for tumor necrosis factor alpha, interleukin 6, and interleukin 23α) and corresponding cytokine expression in the ODN-treated disease group. The levels of mRNA for Toll-like receptors 4, 5, and 9 also largely decreased in the ODN-treated disease group. Our results demonstrated that ODN can inhibit endodontic disease development, bone erosion, and immune response. These results indicate that application of this small molecule offers a new opportunity to design effective therapies that could prevent periapical inflammation and revolutionize current treatment options.

An ex vivo comparison of pressures within dental pulp space using conventional anesthetic technique versus needle-mounted obturator.

INTRODUCTION: The intrapulpal (IP) injection technique is 1 of several ways of obtaining profound anesthesia. There is evidence to suggest that pressure is the primary factor in obtaining anesthesia using IP injection. This is an ex vivo comparison of pressures within dental pulp space using the conventional anesthetic technique versus a needle-mounted obturator technique. METHODS: Twenty extracted anterior and premolar teeth were accessed with a high-speed 169L bur. A saline-filled tube connected to a digital pressure gauge was attached to the apical 10 mm of each tooth in a fixed mount. One operator performed all the injections under moderate pressure. Each tooth was injected twice; first, the tooth was given an IP injection with a normal setup, and then the same tooth was given an IP injection with the modified obturator syringe. The pressure at the apex was recorded for each tooth. A paired sample t test was completed to determine statistical significance. RESULTS: The pressure generated was considerably higher for the obturator group in every tooth when compared with the normal group (P < .001). CONCLUSIONS: IP injection with the obturator resulted in increased pressure at the apex of each tooth. This pressure increase may allow for increased anesthesia when IP injections are indicated.

Comparison of pulp stump wounds created by profile rotary root canal instruments and small-diameter fine diamond burs.

INTRODUCTION: The aim of this investigation was to evaluate and compare the pulp stump wounds created by the following root canal instruments: ProFile rotary files and small-diameter fine diamond burs. METHODS: Extracted mandibular premolars from adult patients with vital pulps and fully formed root canals were collected and stored in formalin. Within 48 hours of extraction, the periapical tissue was fixated to the root with a double coating of ethyl cyanoacrylate, and the pulp chambers were accessed with a #4 round carbide bur and high-speed handpiece in a traditional fashion. The pulp tissue of 10 specimens per group was extirpated at a level approximately 5 mm from the apex by using standard endodontic techniques. The specimens were then examined at ×100 magnification under a digital microscope. Grading criteria were developed, and the wounds were scored. RESULTS: Wounds created by diamond burs were significantly smoother that those created by ProFile rotary files; the mean wound score for diamond burs was 1.4 versus a mean wound score of 3 for ProFiles. After the author's scoring of the wounds, 2 endodontist graders were shown photos of each specimen in a double-blind fashion and instructed to score each specimen as being smooth or rough. To validate the developed scoring system and remove potential observer bias of the author, the data from the double-blind observations were used to complete a cross-tabulation for a Cohen kappa test. CONCLUSIONS: Kappa values demonstrated substantial inter-rater agreement for both groups.

Inhibition of Rgs10 Expression Prevents Immune Cell Infiltration in Bacteria-induced Inflammatory Lesions and Osteoclast-mediated Bone Destruction.

Regulator of G-protein Signaling 10 (Rgs10) plays an important function in osteoclast differentiation. However, the role of Rgs10 in immune cells and inflammatory responses, which activate osteoclasts in inflammatory lesions, such as bacteria-induced periodontal disease lesions, remains largely unknown. In this study, we used an adeno-associated virus (AAV-) mediated RNAi (AAV-shRNA-Rgs10) knockdown approach to study Rgs10's function in immune cells and osteoclasts in bacteria-induced inflammatory lesions in a mouse model of periodontal disease. We found that AAV-shRNA-Rgs10 mediated Rgs10 knockdown impaired osteoclastogenesis and osteoclast-mediated bone resorption, in vitro and in vivo. Interestingly, local injection of AAV-shRNA-Rgs10 into the periodontal tissues in the bacteria-induced inflammatory lesion greatly decreased the number of dendritic cells, T-cells and osteoclasts, and protected the periodontal tissues from local inflammatory damage and bone destruction. Importantly, AAV-mediated Rgs10 knockdown also reduced local expression of osteoclast markers and pro-inflammatory cytokines. Our results demonstrate that AAV-shRNA-Rgs10 knockdown in periodontal disease tissues can prevent bone resorption and inflammation simultaneously. Our data indicate that Rgs10 may regulate dendritic cell proliferation and maturation, as well as the subsequent stimulation of T-cell proliferation and maturation, and osteoclast differentiation and activation. Our study suggests that AAV-shRNA-Rgs10 can be useful as a therapeutic treatment of periodontal disease.

A residual granuloma in association with a dental implant.

At times, dental implants are placed into sites with a history of periapical pathology. Sometimes the infection is active, and other times the tooth may have been extracted years before implant placement. In either case, the possibility exists for long-term residual cysts or infections that can negatively impact the prognosis of the implant. In this case report, an implant is placed into a healed mandibular ridge several months after extraction of the tooth. A radiolucency was noted on routine radiographic examination 2 years later. Surgical inspection and histology revealed a periapical granuloma with acute and chronic inflammatory cells. After surgical curettage of the site, the patient healed without complication. Implants may develop apical pathology as a result of a preexisting long-term residual infection.

Physical effects of sodium hypochlorite on bone: an ex vivo study.

INTRODUCTION: Sodium hypochlorite (NaOCl) accidents during endodontic therapy require accurate and prompt action. Understanding the physical properties of bone and evaluating the resultant cell damage from NaOCl exposure could improve management of these accidents. This study assessed the physical and histologic properties of dog femurs exposed to NaOCl for a period of 30 minutes. METHODS: Four dog femurs were dissected and frozen. Twelve 40-mm-long sections were obtained and cut into 20-mm paired sections. Adjacent surfaces were randomly selected for shallow injection of either NaOCl or saline. Sections were visually assessed for gross physiologic effects. The structural integrity of the cancellous bone was measured by micro-indentation testing, and statistical analysis of needle penetration was conducted. Histologic evaluation of specimens was also conducted. RESULTS: Grossly, NaOCl caused remarkable changes in cancellous structure, leaving craters of apparent demineralization. There was a significant difference in mean depth of needle penetration and demineralization between the treatments (P = .0397), with NaOCl showing greater mean depth than saline. The NaOCl group showed degradation of the organic matrix collagen. CONCLUSIONS: These results indicate that NaOCl compromises the integrity of cancellous bone. Calcified elements, especially cortical bone, appeared less affected.

Effect of sodium hypochlorite on human pulp cells: an in vitro study.

BACKGROUND: The purpose of this study was to determine the effect of sodium hypochlorite (NaOCl) on human pulp cells to provide an aid in determining its optimum concentration in maintaining the viability of remaining pulp cells in the revascularization of immature permanent teeth with apical periodontitis. STUDY DESIGN: Human pulp tissue cells taken from extracted third molars were plated, incubated, and subjected to various concentrations of NaOCl (0.33%, 0.16%, 0.08%, and 0.04%) for 5-, 10-, and 15-minute time intervals to simulate possible contact times in vivo. The Cell Titer-Glo Luminescent Cell Viability Assay was used to determine the number of viable cells present in culture following treatment. RESULTS: The results showed an increase in cell viability with the lowering of NaOCl concentration. The use of 0.04% NaOCl was similar to the control, indicating nearly complete preservation of cell viability at all time intervals tested. As sodium hypochlorite concentration increased from 0.04% to 0.33%, cell viability decreased correspondingly. CONCLUSIONS: The results indicate that the lowest concentration of NaOCl tested did not affect the viability of cells. This may prove beneficial in developing a new treatment protocol to help preserve existing vital pulp cells in revascularization cases.

Comparison of root canal preparation using reciprocating Safesiders stainless steel and Vortex nickel-titanium instruments.

OBJECTIVE: The aim of the present study was to assess several parameters related to the clinical usage of 2 root canal preparation instruments: Vortex .06 rotary nickel-titanium instruments, and Safesiders reciprocating stainless steel instruments. STUDY DESIGN: Fifty extracted mandibular molars with mesial root canal curvatures between 20° and 50° were divided into 2 groups and embedded in acrylic resin inside a modified Bramante muffle system. All root canals were prepared to ISO size 40 using either Vortex .06 rotary nickel-titanium-instruments in a low-torque motor or Safesiders stainless steel instruments in a proprietary reciprocating handpiece. The following parameters were evaluated: straightening of curved root canals, working safety issues (perforations, instrument breakages, canal blockages, loss of working length), postpreparation root canal cross-section, and working time. RESULTS: The Vortex .06 instruments maintained canal curvatures well, with the mean degree of straightening recorded as 0.72°. Safesiders instruments demonstrated significantly more canal straightening, with the mean degree of straightening recorded as 15.5°. More than 90% of the root canals prepared with the Vortex .06 instruments resulted in a round or oval cross-section, whereas the Safesiders instruments produced round or oval cross-sections 60% of the time. Neither of the 2 instruments could effectively prepare 100% of the root canal circumference. The area of dentin removed and the remaining dentin thicknesses from each region were similar for the 2 groups. Six procedural incidents were recorded for the Vortex .06 group, compared with 19 for the Safesiders group. There were no instrument fractures recorded in either group. Mean working time was significantly shorter for Vortex .06 (279 s) than for Safesiders (324 s). CONCLUSIONS: Vortex .06 maintained the original root canal curvatures well, whereas Safesiders instruments demonstrated significant straightening and irregular preparation shapes when used in sizes larger than ISO 20. Preparation of the complete circumference of the root canal was not possible with either system. Fewer procedural errors occurred with the Vortex instruments.

Comparison of the amount of transportation when using a precurved instrument in a sonic handpiece vs. nickel-titanium rotary files.

Three-dimensional cleaning of the root canal system along its basic shape is one of the main goals in endodontics. A sonic handpiece is a helpful adjunct that can aid in accomplishing this goal; however, its use has been limited due to the risk of transporting the apices' original position. Precurving sonic files may reduce transportation. For this study, 35 plastic blocks were randomly assigned to two groups, one of which (n = 16) was instrumented by nickel-titanium rotary files (to a size 40), while the second group (n = 18) was instrumented by a sonic handpiece with precurved files. Similar blocks were instrumented with noncurved sonic files and used as controls. Radiographs taken before and after instrumentation were compared. Of the 18 apices instrumented by the sonic handpiece with precurved files, seven were not transported. By comparison, 8 of the 16 apices instrumented by nickel-titanium files did not transport. When transportation did occur, it was less than 0.5 mm for either technique. The control blocks instrumented by the sonic handpiece with straight files were transported significantly. An ANOVA with a post hoc Tukey's test showed no statistically significant difference between the file systems. Based on the results, precurving sonic files to match the canal contour may allow for efficient cleaning without undue transportation.

Comparison of classic endodontic techniques versus contemporary techniques on endodontic treatment success.

INTRODUCTION: Many recent technological advancements have been made in the field of endodontics; however, comparatively few studies have evaluated their impact on tooth survival. This study compared the survival rates of endodontic treatment performed by using classic techniques (eg, instrumentation with stainless steel hand files, alternating 5.25% NaOCl and 3% H2O2 irrigation, mostly multiple treatment visits, and so on) versus those performed using more contemporary techniques (eg, instrumentation with hand and rotary nickel-titanium files, frequent single-visit treatment, NaOCl, EDTA, chlorhexidine, H2O2 irrigation, warm vertical or lateral condensation obturation, use of surgical microscopes, electronic apex locators, and so on). METHODS: Using a retrospective chart review, clinical data were obtained for 984 endodontically treated teeth in 857 patients. Survival was defined as radiographic evidence of the treated tooth being present in the oral cavity 12 months or more after initial treatment. A mixed-model Poisson regression analysis was used to compare failure rates. RESULTS: Of the 459 teeth in the classic group, there was an overall survival rate of 98% with an average follow-up time of 75.7 months. Of 525 teeth in the contemporary group, there was an overall survival rate of 96%, with an average follow-up time of 34 months. Considerably more treatments in the classic group were completed in multiple appointments (91%) than in the contemporary group (39%). More teeth in the classic group underwent posttreatment interventions (6.7% vs 0.9%, respectively). CONCLUSIONS: No statistically significant difference was noted between the two technique groups or between single or multiple visits in terms of survival.

Volumetric expansion of gutta-percha in contact with eugenol.

The aim of this study was to compare the volumetric expansion of gutta-percha in the presence of eugenol or physiologic saline over time. Sections of gutta-percha cones were scanned to determine their total volume and surface area. They were then placed in sealed test tubes with either 2 microL eugenol or 2 microL saline and allowed to soak for 24 hours, 7 days, or 30 days. The results were scanned again to determine the volumetric changes in the material after placement in the test solutions. The results were statistically analyzed by using t tests and analysis of variance. Specimens soaked in eugenol showed a dramatic increase in volumetric expansion versus the saline group at all time periods. Sealers that incorporate eugenol could be attributed to gutta-percha volumetric expansion over time, thereby creating a better seal of the obturation material.

Comparison of the success of root canal therapy in HIV/AIDS patients and non-infected controls.

This study compared the rate of successful endodontic treatments between two cohorts of patients with similar teeth, one group with HIV/AIDS and one without. A retrospective chart review was performed on two cohorts, with 50 teeth in each cohort. There was no statistically significant difference in endodontic success between the two groups. The failure groups were small, with no significant trends.

Observations of biofilm growth on human dentin and potential destruction after exposure to antibiotics.

OBJECTIVES: This study was performed to observe biofilm formation on dentin and to then observe effects of clinically achievable antimicrobial drug concentrations on these biofilms. STUDY DESIGN: Wild-strain endodontic bacteria were anaerobically cultured from necrotic pulps of extracted human teeth and used to grow biofilms on sterilized dentin slices in an anaerobic chamber for 12 days. Then these biofilms were exposed to ampicillin, doxycycline, clindamycin, azithromycin, or metronidazole. Each day for 8 days, specimens were fixed using 2% glutaraldehyde and examined with a scanning electron microscope (SEM). RESULTS: The SEM images revealed the presence of a mature biofilm after 8 days of growth and that none of the antibiotics tested was effective in eliminating the biofilm even after 8 days of exposure. CONCLUSION: Biofilms are formed in a few days and are resistant to antimicrobial drugs.

Comparison of preparation design and material thickness on microbial leakage through Cavit using a tooth model system.

Few studies have compared Cavit thickness and access design as factors in microbial leakage. The present study used an acrylic tooth model to measure leakage of Streptococcus mutans. Pilot studies confirming the sterility of Cavit showed it will inhibit microbial growth for 2 days. The experiments compared class I preparations where Cavit thickness was 4 mm with class II preparations where thickness was 2-3 mm. Accesses sealed with cotton pellets were compared with those without cotton. Results of the study showed no bacterial contamination in any of the class I samples (up to 14 days). Some class II samples showed contamination at day 1 (3 out of 14), with all contaminated at day 7 (14 of 14), yet only 1 contaminated at day 14 (1 out of 14). The results suggest that a 4-mm thickness of Cavit should prevent bacterial ingress for at least 2 weeks, but microbial leakage may occur if temporary thickness is less than 3 mm or in a complex access preparation.