Apical Periodontitis in Vital and Nonvital Teeth: Clinical and Radiographic Features.

Apical periodontitis (AP) is a common inflammatory condition predominantly caused by the response of the immune system to microbial invasion within the root canal system. Contrary to conventional perception, AP may occur in vital teeth with inflamed pulp; adding complexity to diagnosis and treatment. AP, due to its frequent lack of symptoms and reliance on radiographic evaluation for detection, often presents diagnostic challenges. In addition, AP pathogenesis involves complex interactions between microbial virulence and host immune response at the cellular and molecular levels. Comprehensive diagnostic procedures, including patient history, clinical examination, and radiographic evaluation, are essential for early detection and necessary intervention, with the recognition of clinical signs and symptoms underscoring the importance of regular dental evaluations. The current review primarily discusses the radiographic and clinical features of AP in vital and non-vital teeth; introducing a new taxonomic classification to improve diagnostic precision and treatment outcomes. Moreover, it proposes different treatment categories/options for the management of AP, based on pulp status as well as clinical and radiographic findings; emphasizing vital pulp therapy and root canal treatment for vital and non-vital teeth with AP, respectively. Furthermore, the global and regional epidemiology of AP is presented, along with its association with systemic health conditions; e.g., cardiovascular diseases, diabetes mellitus, and adverse pregnancy outcomes. Moreover, future research directions are advocated to improve the efficacy and predictability of diagnosis and treatments; paving the path for clinicians in early detection, accurate diagnosis, and effective management of AP to enhance oral health outcomes.

Virtual reality and haptics in dental education: Implementation progress and lessons learned after a decade.

INTRODUCTION: The search for alternative training environments in dentistry responded mainly to scarcity and lack of standardisation of training material and non-availability of specific clinical procedures. The development of haptic virtual reality (VR) dental trainers provides a platform where irreversible procedures can be safely and unlimitedly practised. The aim of this study was to assess the educational implementation of these devices and evaluate schools' satisfaction. METHODS: Dental schools that were using haptic VR dental trainers, were approached. The Dental Trainer User Inventory (DTUI), addressing the educational implementation and users' satisfaction, was developed and distributed. RESULTS: Twenty-seven schools completed the DTUI. The total number of VR dental trainers available varied from one to 42 devices with a mean of 7 devices. The dental trainer was mostly made available from the first year (63.0%) of the undergraduate program, but it was mostly integrated into the curriculum by the third year (70.4%). Curricular integration was reported by 18 schools (66.7%), while nine schools (33.3%) indicated that they had not yet achieved integration. Twenty-one schools (69.4%) were 'satisfied' or 'very satisfied' with the devices, while two schools (7.4%) were dissatisfied and six schools (22.2%) were neither satisfied nor dissatisfied. CONCLUSION: VR haptic dental trainers are implemented in multiple dental programs and are also being used for educational research and clinical training. Even though curricular changes and teachers' acceptance remain a challenge, most schools are satisfied with VR haptic dental trainers and would recommend the device to other schools.

Students' learning environment perception and the transition to clinical training in dentistry.

INTRODUCTION: The learning environment (LE) influences students' behaviour, and predicts academic achievement, satisfaction and success. Measuring students' perception of the LE provides relevant information for curricular quality assurance. In this study, a LE assessment was used to observe variations in students' LE perception throughout the curriculum, to illustrate the possible influence that preclinical training (Pt) and clinical training (Ct) have on students' learning experience. MATERIALS AND METHODS: All students in the six-year undergraduate dental programme (n = 849) at the Academic Centre for Dentistry Amsterdam (ACTA) were approached and divided into Pt and Ct groups according to their training phase in the curriculum. The LE was assessed using the Dundee Ready Educational Environment Measure (DREEM), and the results were evaluated using the Statistical Package for the Social Sciences (SPSS) software for distribution (Kolmogorov-Smirnov normality test), internal reliability (Cronbach's alpha) and comparative analysis (one-way ANOVA). RESULTS: The questionnaire was completed by 216 (response rate=65%) Pt students and by 379 (response rate=75%) Ct students. With a general DREEM score of 124.3, significantly higher scores were found during Pt (DREEM=133.4) in comparison with the Ct phase of the curriculum (DREEM=119.2). DREEM scores steadily decreased throughout the 6-year curriculum, with the highest drops in LE perception observed in the second and third years of the programme. Significant differences in all DREEM domains were observed, with lower scores for Ct. CONCLUSION: Students' LE perception deteriorates throughout the curriculum, especially within the Pt-Ct transition, during the second and third years of the programme. An inferior LE perception was observed in every domain of the LE questionnaire within this transition showing a learning experience, which requires an educational intervention. Further research is required to better understand the educational needs of the Pt-Ct transition at this school.

Effectiveness of the new mandatory mouthguard use and orodental injuries in Dutch field hockey.

ObjectivesUp to 68% of field hockey players have experienced at least one orodental injury in their sport career. Therefore, the Royal Dutch Hockey Association (KNHB) made mouthguard use mandatory for field hockey players during competition and training from August 2015 onwards.This study evaluates the effects of the new regulations on mouthguard use and the occurrence of injuries in Dutch field hockey.MethodsA 35-item online questionnaire about mouthguard use and orodental injuries was sent to 13 field hockey clubs in the Netherlands. Absolute numbers and percentages of mouthguard ownership, mouthguard use, number and type of injuries were assessed. The results were related to comparable data before mandatory mouthguard use. Associations of gender and training frequency with the number of injuries were analysed with logistic regression.ResultsIn total, 1169 hockey players were included in the study and almost all owned a mouthguard (females:99.6%, males:93.7%), which significantly increased after implementation (p < 0.001). 90.6% of the respondents wore a mouthguard during matches and 70.1% during training. Of the 1169 players, 68(5.8%) experienced at least one orodental injury after the implementation with a total of 100 injuries. Injuries happened more often during matches (63.2%) than during training (36.8%). Lip cuts account for most of the injuries, the number of broken (p = 0.116) and knocked out teeth (p = 0.026) decreased.ConclusionAlthough mouthguard use already increased in recent years, the new regulations led to an additional increase and a successful change of attitude towards mouthguard use. Most importantly, the severity of orodental injuries decreased measurable.

First experiences with patient-centered training in virtual reality.

CONTEXT: In preclinical dental education, plastic and extracted teeth have been broadly used for skills training without specific focus on the patient behind the procedure. A patient-centered approach remains challenging in traditional simulation, which does not resemble realistic clinical situations. OBJECTIVE: This article describes the development and first experiences with a patient-centered virtual reality training module (PC-VR) that allows dental care providers to prepare, beforehand and in virtual reality (VR), specific procedures required by their patients. Experiences with this patient-centered practice are described to reflect on its value for clinical training in dentistry. DESIGN: Using an intraoral scanner, digital impressions of 10 patients were made; these served as stereolithography (STL) digital files, which were converted into volumetric haptic models for display in a VR dental simulator. In this study, students' experiences were investigated through a short open-answer survey in 2018. Atlas.ti was used for qualitative analysis of the answers through the inductive methodology of the grounded theory approach. RESULTS: Drillable virtual models of real patients were made available for training using VR. Inductive analysis of the experiences identified 5 dimensions describing the main features of PC-VR: added value, competence development, self-efficacy, outcomes, and room for development. CONCLUSION: This article provides a general overview of the possibilities and challenges of the implementation PC-VR in dental education. Although concrete effects on trainees' self-confidence and performance are yet to be determined, all participants appreciated the opportunity to explore clinical situations before experiencing them in the context of a real patient.

The Effect of Variations in Force Feedback in a Virtual Reality Environment on the Performance and Satisfaction of Dental Students.

INTRODUCTION: The aim of this study was to investigate the transfer of skills between various levels of force feedback (FFB) using the Simodont dental trainer (Moog, Nieuw-Vennep, the Netherlands). Students practiced a manual dexterity exercise in a virtual reality environment at a standard level of FFB and then were tested at the standard and an altered level of FFB. In addition, the students' satisfaction with the training exercise was evaluated. METHODS: One hundred twenty-six first-year dental students were randomly distributed into four groups and underwent a manual dexterity test in the virtual reality environment with automatic assessment after a 3-month period of practicing with standard FFB. The test consisted of drilling with the standard FFB and an altered level of FFB to evaluate the effect on performance. After the test, the participants completed a questionnaire. RESULTS: The results showed that 74% of the students who passed completed between one of three and three of three successful attempts at FFB levels at which they had not previously practiced. CONCLUSIONS: The results of this study imply that if students practice a sufficient amount of time at one level of FFB, a skill is transferable from one level of FFB to another.

Acidic and alkaline chemicals' influence on a tricalcium silicate-based dental biomaterial.

Bioactive hydraulic tricalcium silicate materials are commonly used in several dental procedures. Mineral Trioxide Aggregate (MTA) is one such material, which is used in a variety of clinical applications, the most recent of which is root canal sealing material, during which, the MTA potentially comes in contact with remnants of the chemical agents used for disinfecting root canals. The effects of commonly used root canal irrigating solutions on MTA have not been investigated in depth, thus far. The aim of this study was to determine the effect of five common chemical agents used in root canal preparation (sodium hypochlorite/NaOCl, ethylene diaminetetraacetic acid/EDTA, mixture of sodium hypochlorite and etidronic acid/NaOCl + EA, mixture of EDTA and Chlorhexidine/QMix, or saline) on a commercial tricalcium silicate (MTA Plus). Samples were analyzed using scanning electron microscopy with energy dispersive spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy and Inductively coupled plasma techniques to see effects of phases formed and calcium ion release. Specimens immersed in NaOCl and NaOCl + EA had strong peaks for calcium hydroxide, but materials exposed to EDTA and QMix had lesser XRD peaks for calcium hydroxide. The calcium hydroxide peak in the XRD indicates hydration of tricalcium silicate and formation of amorphous calcium silicate hydrate. Calcium released from samples immersed in EDTA and NaOCl was less than in NaOCl + EA and QMix solutions. Fewer calcium phosphate crystals and less calcium hydroxide were observed with the samples in NaOCl, EDTA and QMix, which could have an important impact as it negatively influences the bioactivity. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 377-387, 2019.

The Effect of Force Feedback in a Virtual Learning Environment on the Performance and Satisfaction of Dental Students.

INTRODUCTION: This study investigated the effect of force feedback (FFB) on student performance in a virtual learning environment (VLE) using the Simodont dental trainer (Moog, Nieuw-Vennep, the Netherlands) and evaluated the students' satisfaction with and without FFB. METHODS: The Simodont dental trainer, which was used as a VLE, was randomly assigned to 101 first-year dental students with no previous experience in cutting a tooth or working in a VLE with FFB. This study was designed as a crossover study. One half of the students practiced without FFB, whereas one half practiced with FFB. Both groups practiced four sessions lasting 45 minutes on a cross preparation. In the fifth session, test 1 was scheduled. After test 1, the same practicing and testing protocol was followed, although the environment was switched. After test 2, participants filled out a questionnaire. For the statistical analysis, only the questionnaires of the students who participated in both tests were processed. RESULTS: The results of test 1 and test 2 revealed that only students who used FFB were able to pass the tests. The questionnaire outcomes supported the results of both tests; 100% of the students preferred working with FFB. CONCLUSIONS: The results suggest that FFB is important for performance in a VLE and essential for satisfaction.

Calcium Hydroxide Treatment Does Not Alter the Susceptibility of Enterococcus faecalis Biofilms to Sodium Hypochlorite.

OBJECTIVE: To investigate the influence of calcium hydroxide (Ca(OH)2) on susceptibility to disinfection with sodium hypochlorite (NaOCl) of biofilm bacteria. METHODS: Monospecies biofilms of eight Enterococcus faecalis strains were subjected to a 2-h challenge with Ca(OH)2. After a recovery phase, the biofilms were treated with a concentration of NaOCl that was lower than the minimum inhibitory concentration. In a metabolic assay, the efficacy of NaOCl disinfection in Ca(OH)2-challenged biofilms and unchallenged biofilms was evaluated. The data were analyzed with Mann-Whitney U and Kruskall- Wallis tests. A P value of less than 0.05 was considered statistically significant. RESULTS: There were marginal differences in susceptibility to NaOCl among the E. faecalis strains. After the Ca(OH)2 challenge, seven strains remained equally susceptible to NaOCl disinfection whereas one strain became more resistant to NaOCl (P=0.03). CONCLUSION: After a Ca(OH)2 challenge, in general E. faecalis remained equally susceptible to disinfection with NaOCl.

Patterns of orodental injury and mouthguard use in Dutch field hockey.

BACKGROUND: Orodental injuries in field hockey are a growing cause of concern that requires attention. OBJECTIVE: The objective of this cross-sectional study was to investigate the patterns of orodental injury, and the use of mouthguards in Dutch national field hockey. MATERIALS AND METHODS: In the period from 1 May to 31 July 2014, a 33-item questionnaire about orodental injury and mouthguard use was sent to 7 field hockey clubs in the Netherlands. Data were analysed using 2 multivariable logistic (non-)linear regression per outcome measurement: (1) orodental injury and (2) type of mouthguard. RESULTS: Out of 6585 players, 1299 (20%) responded sufficiently and were eligible for the study. In total, 214 hockey players (16%) experienced at least 1 orodental injury in their career. The injuries were less severe in athletes who wore a mouthguard during an accident than in those who did not, OR=2.1 to 3.3, p≤0.05. Players without mouthguard sustained broken and knocked out teeth more frequently, while players with a mouthguard had more lip cuts (p≤0.05). Players complained less about custom-made than about mouth-moulded mouthguards (p≤0.05). Also, males were more at risk for an orodental injury, OR=1.4 (95% CI 1.0 to 1.9), and were less likely to have a custom-made mouthguard, OR=0.7 (95% CI 0.6 to 0.9), than females. CONCLUSIONS: A substantial number of field hockey players suffers from orodental injury. Mouthguards should be included in prevention strategies as they are associated with less severe injuries and patterns of injury are to be taken into account when targeting specific groups.

Additional disinfection with a modified salt solution in a root canal model.

OBJECTIVES: The aim of this study is to investigate the disinfecting properties of a modified salt solution (MSS) and calcium hydroxide (Ca(OH)2) in a non-direct-contact ex-vivo model. METHODS: Seventy-four single-canal roots infected with Enterococcus faecalis were treated with 1% sodium hypochlorite (NaOCl) irrigation or with NaOCl irrigation with subsequent dressing with MSS or Ca(OH)2. After removal of the dressings, the roots were filled with bacterial growth medium and incubated for seven days to enable the surviving bacteria to repopulate the root canal lumen. Growth was determined by sampling the root canals with paper points before treatment (S1), after treatment (S2) and incubation after treatment (S3). The colony forming units were counted at S1 and S2. At S3, growth was determined as no/yes regrowth. The Kruskal-Wallis, McNemar and χ(2) test were used for statistical analyses. RESULTS: At S2, in the NaOCl group, growth was found in 5 of 19 root canals. After the removal of MSS or Ca(OH)2 bacteria were retrieved from one root canal in both groups. At S3, repopulation of the root canals had occurred in 14 of 19 roots after sole NaOCl irrigation, 6 of 20 roots after MSS-dressing and in 14 of 20 roots after Ca(OH)2-dressing. MSS was more effective in preventing regrowth than Ca(OH)2 (P=0.009). CONCLUSIONS: The modified salt solution prevented regrowth in roots which indicates that it can eliminate persistent bacteria. Dressing the root canals with Ca(OH)2 did not provide additional disinfection after NaOCl irrigation.

Influence of Irrigation Sequence on the Adhesion of Root Canal Sealers to Dentin: A Fourier Transform Infrared Spectroscopy and Push-out Bond Strength Analysis.

INTRODUCTION: There is a lack of evidence on the chemical interaction between sealers and dentin. The influence of irrigation on the chemical interaction between root canal sealers and dentin was analyzed by using Fourier transform infrared spectroscopy (FTIRS) and measurement of dislocation resistance. METHODS: Single-rooted teeth (n = 120) were instrumented with 3% NaOCl as the irrigant and divided into 4 groups (n = 30) on the basis of irrigation protocol: group 1, 3% NaOCl, 17% EDTA, water; group 2, 17% EDTA, 3% NaOCl, water; group 3, 3% NaOCl, QMix, water; group 4, 3% NaOCl, water. Each group was divided into 3 subgroups (n = 10) on the basis of the root canal sealer: A, epoxy resin (AH Plus); B, silicone (RoekoSeal); C, calcium hydroxide (Sealapex). The dislocation resistance was assessed by using push-out bond strength test. The data were statistically analyzed by three-way analysis of variance and Holm-Sidak tests (P = .05). Dentin powder treated as per the conditioning protocols mentioned was mixed with the sealers and analyzed by FTIRS. RESULTS: A significant interaction was observed between irrigation protocol, type of sealer, and root segment (P < .001) for AH Plus but not for RoekoSeal and Sealapex (P > .05). AH Plus showed the highest bond strength (P < .05). FTIRS showed chemical bonding between AH Plus and dentinal collagen. In groups 2 and 4, no chemical bonding was observed. CONCLUSIONS: Bond strength of sealers is differentially affected by the irrigation protocol. The epoxy resin sealer AH Plus chemically bonds to dentinal collagen. This interaction is influenced by the irrigation protocols.

Outcome of Direct Pulp Capping with Mineral Trioxide Aggregate: A Prospective Study.

INTRODUCTION: The aim of this experimental study was to assess the outcome of direct pulp capping with mineral trioxide aggregate (MTA) after complete excavation of caries in permanent dentition with a 2-visit treatment protocol. METHODS: Sixty-four teeth with deep carious lesions were consecutively selected. The mean age of the patients was 36.1 ± 15 years. An initial diagnosis of deep caries, with no irreversible pulp involvement, was made. Excavation of caries was performed under a rubber dam and operating microscope magnification. White MTA was applied, and a provisional restoration was placed. At the following appointment, positive sensibility testing and the MTA setting were confirmed. Bonded composite restorations were placed afterward. The patient was recalled at least 1 year after treatment for clinical and radiographic control. Outcome was described as success or failure. Success was defined as lack of complaints from the patient, positive reaction to cold testing, no sensitivity to percussion, and no widening of the periodontal ligament on the recall periapical radiograph. RESULTS: Forty-six teeth (77.9%) were recalled after 3.6 years (standard deviation = 1.1 years). The overall success rate was 91.3%. The success rate in occlusal caries was 100% and 89.7% in proximal caries (difference = 10.3%; 95% confidence interval [CI], 8.5-89.1). The success rate in initial caries was 94.7% and 88.9% in secondary caries (difference = 5.8%; 95% CI, -48.1 to 59.7). The success rate in patients younger than 40 years was 100% and 80% in patients aged 40 years or older (difference = 20%; 95% CI, 4.2-35.8). CONCLUSIONS: Direct pulp capping with MTA after pulp exposure during excavation of deep caries could maintain pulp vitality in permanent teeth when a 2-visit treatment protocol is observed.

Effect of a two-step placement procedure on the dislocation resistance of a methacrylate resin-based root canal sealer: a proof of concept.

PURPOSE: To investigate whether the placement of a methacrylate root canal sealer or a conventional epoxy root canal sealer in two steps increases their dislocation resistance when compared to a one-step placement procedure. MATERIALS AND METHODS: Eighty single-rooted teeth were randomly allocated to 4 groups (n=20). All canals were instrumented to size 40, 0.06 taper and irrigated according to a standardized protocol. Root canal filling was conducted as follows: group 1: methacrylate sealer placed in two steps; group 2: methacrylate sealer placed in one step; group 3: epoxy sealer placed in two steps; group 4: epoxy sealer placed in one step. After setting, thin slices at different root levels were obtained and submitted to push-out testing. RESULTS were analyzed with non-parametric tests to compare the two-step procedures to their one-step counterparts. Failure modes were determined by stereomicroscopy. Random untested methacrylate sealer specimens were also examined with scanning electron microscopy. RESULTS: At each root level, dislocation resistance was significantly higher for the two-step procedure than for the one-step procedure using the methacrylate sealer (p=0.003, p=0.005, p<0.001) but not the epoxy sealer (p=0.83, p=0.1, p=0.06). Among root levels, there were no significant differences in dislocation resistance in the methacrylate sealer two-step group, while all other groups showed differences. CONCLUSION: A two-step placement procedure resulted in significantly higher dislocation resistance for the methacrylate sealer but not for the epoxy sealer.

Cone-beam computed tomographic scans in comparison with periapical radiographs for root canal length measurement: an in situ study.

INTRODUCTION: The primary aim of this study was to compare the precision of root canal length determination on cone-beam computed tomographic (CBCT) scans and periapical radiographs (PAs) with the actual root canal length. The secondary aim was to examine the influence of tooth type on root canal length measurements as assessed on CBCT scans and PAs. METHODS: In total, 40 root canals of 33 teeth (molars, premolars, canines, and incisors) out of 5 dentate maxillas of human cadavers were included. Root canal length measurement was performed by a consensus panel (2 examiners) on CBCT scans (3D Accuitomo 170; J Morita, Kyoto, Japan) and digital PAs. After straight-line access opening, a #15 file was fixated in every root canal at the length measured on CBCT scans. All teeth were extracted, and the root canal containing the file was uncovered. Measurements made on images taken with a digital camera (AxioCam; Carl Zeiss, Sliedrecht, The Netherlands) linked to a stereozoom microscope (Stemi SV6, Carl Zeiss) were used as the actual root canal length. RESULTS: When all roots were examined together, it was not clear which method is better for all types of teeth. For root canals of anterior teeth, there was no significant difference between the 2 methods. For root canals of posterior teeth, CBCT images gave results significantly closer to the actual root canal length in comparison with PAs (t value = -1.96; critical value is 1.74 with a significance level of 0.05). CONCLUSIONS: Root canal length measurements of posterior maxillary teeth were more accurate when assessed by CBCT images than PAs.

Influence of the dentinal wall on the pH of sodium hypochlorite during root canal irrigation.

INTRODUCTION: The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels. METHODS: A novel clinically representative model that scales with the ratio of the irrigant volume to the dentin surface area of a human root canal was used. Three standardized bovine dentin bars (2 × 2 × 10 mm) were placed in a plastic test tube. A total of 150 tubes were distributed in 29 groups. In the first experiment, the pH of various NaOCl solutions, with different concentrations (3%, 6%, and 9%) and starting pH levels (5 and 12), was monitored during exposure to dentin between 10 and 300 seconds. In a second experiment, the effect of agitation (45 Hz) and pretreatment of dentin with 17% EDTA on the pH levels of various NaOCl solutions was studied after 30 seconds of exposure to dentin. The short-term chemical stability of the tested solutions was assessed for both the concentration and the pH. RESULTS: The exposure time (P < .001) and concentration of the NaOCl solution (P < .011) significantly influence the pH level after exposure to dentin. However, the change in pH is too small to induce a change in the irrigant antimicrobial/tissue dissolution capacity. CONCLUSIONS: Agitation of the irrigant and preconditioning of the dentin did not alter the pH (P > .05). Both the pH 5 and pH 12 solutions were chemically stable for 1 hour.

Free available chlorine concentration in sodium hypochlorite solutions obtained from dental practices and intended for endodontic irrigation: are the expectations true?

OBJECTIVE: Sodium hypochlorite (NaOCl) is an important tool in root canal disinfection although it is well known that the shelf-life of NaOCl is limited. In this study, NaOCl solutions that were collected from dental practices and were intended for endodontic irrigation were investigated to see whether they contained the expected concentration of free available chlorine. METHOD AND MATERIALS: NaOCl solutions were collected from dental practices. The concentration of available chlorine per sample was determined with iodometric titration and the pH was measured. Each participating dentist completed a questionnaire that requested data on a range of issues relating to the assumed concentration of NaOCl and handling of the sample. RESULTS: Eighty-four samples with questionnaires were received. NaOCl was purchased from supermarkets and drugstores (36%), dental suppliers (48%), or pharmacies (16%). The median expected concentration was 2% (n = 36). On average, 27% less available chlorine was measured than the dentist assumed was in the sample (P < .001). Fifteen percent of samples contained less than 1% available chlorine, which is needed for tissue dissolution and disinfection. The average pH was 11.5. CONCLUSION: The greatest differences in concentrations were found in NaOCl sourced from supermarkets or drugstores. Future studies should elucidate the cause of this discrepancy. CLINICAL RELEVANCE: In the meantime it is recommended to purchase NaOCl from professional suppliers, because this group showed the most reliable content of free available chlorine.

Cavitation measurement during sonic and ultrasonic activated irrigation.

INTRODUCTION: The aims of this study were to quantify and to visualize the possible occurrence of transient cavitation (bubble formation and implosion) during sonic and ultrasonic (UAI) activated irrigation. METHODS: The amount of cavitation generated around several endodontic instruments was measured by sonochemiluminescence dosimetry inside 4 root canal models of human dimensions and varying complexity. Furthermore, the spatial distribution of the sonochemiluminescence in the root canal was visualized with long-exposure photography. RESULTS: Instrument oscillation frequency, ultrasonic power, and file taper influenced the occurrence and amount of cavitation. In UAI, cavitation was distributed between the file and the wall extending beyond the file and inside lateral canals/isthmuses. In sonic activated irrigation, no cavitation was detected. CONCLUSIONS: Cavitation was shown to occur in UAI at clinically relevant ultrasonic power settings in both straight and curved canals but not around sonically oscillating instruments, driven at their highest frequency.

Volumetric changes in apical radiolucencies of endodontically treated teeth assessed by cone-beam computed tomography 1 year after orthograde retreatment.

INTRODUCTION: Cone-beam computed tomography (CBCT) allows us to assess in 3 dimensions the location and size of periapical radiolucencies. We aimed to assess by CBCT scans the volumetric changes of periapical radiolucencies in endodontically treated teeth 1 year after orthograde retreatment. METHODS: Forty-five root-filled teeth with persistent apical periodontitis requiring endodontic orthograde retreatment from 37 individuals were included in the study. The research protocol was approved by the VU University Medical Center Amsterdam ethics committee (2007/265), and the participants signed a letter of consent. We made 2 CBCT scans for every patient, the first one before retreatment and the second one a year later. Two observers measured independently the volume of radiolucencies on CBCT images by using the AMIRA software. The intraclass correlation coefficient was used to evaluate interobserver agreement, and the Wilcoxon signed rank test was used to assess pretreatment and post-treatment volume size. RESULTS: The intraclass correlation coefficients were 0.994 and 0.998 for the scans before retreatment and 1 year after, respectively. The recall rate was 78% for the teeth and 73% for the patients. The volumetric change in periapical radiolucencies 1 year after retreatment was statistically significant (z = -3.112, P < .005). The volume of periapical radiolucencies reduced in 20 teeth (57%), remained unchanged in 8 (23%), and increased in 7 (20%). CONCLUSIONS: One year after endodontic orthograde retreatment, the volume of periapical radiolucencies reduced significantly in 57% of the teeth.

The validity of cone-beam computed tomography in measuring root canal length using a gold standard.

INTRODUCTION: The distance between a coronal reference point and the major apical foramen is important for working length determination. The aim of this in vitro study was to determine the accuracy of root canal length measurements performed with cone-beam computed tomographic (CBCT) scans using a gold standard. METHODS: A total of 162 teeth (198 root canals) in 16 dry human dentulous mandibles were scanned using a 3DX-Accuitomo CBCT scanner (Morita 3DX; J Morita Mfg Corp, Kyoto, Japan). The root canal length was measured with CBCT data. All teeth were extracted atraumatically and endodontically accessed; the root canal length was measured blindly using a #10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) and served as the gold standard. RESULTS: The mean absolute difference of the CBCT-based root canal length from the gold standard was 0.46 mm (95% confidence interval, 0.41-0.50 mm). Only in 9 of 198 (4.5%) roots did the difference between the CBCT-based root canal length and the gold standard exceed 1 mm. CONCLUSIONS: CBCT-based root canal length measurements are accurate and reliable when compared with a gold standard.