Apical filling characteristics of carrier-based techniques vs. single cone technique in curved root canals.

OBJECTIVES: In this in vitro study, we assessed filling characteristics (adaptation, homogeneity, sealer percentage, position of the carrier) of warm and cold obturation methods in curved root canals. MATERIALS AND METHODS: A reciprocating method was used to prepare 90 curved roots (25 ° average curvature) to an apical size of 25.08. They were then obturated with either (A) Guttafusion (VDW, Munich, Germany), (B) Thermafil (Maillefer, Ballaigues, Switzerland) or (C) single cone technique using 25.08 gutta-percha (VDW) and sealer (2Seal easymix) (n = 30 each group). Five sections in 1-mm steps were obtained from each root, beginning 1 mm short of the apex. The percentage of voids in contact with root canal walls (PVO), the proportion of voids per area (PVA) and the percentage of sealer per area (PSA) were measured. RESULTS: Little to no differences between Guttafusion and Thermafil were seen in curved root canals with respect to adaptation and homogeneity in the apical region. Both methods showed significantly better adaptation and homogeneity than the single cone technique. The proportion of sealer was significantly greater when roots were obturated with Guttafusion than with Thermafil, but both warm obturation techniques had significantly smaller sealer areas than the single cone technique. CONCLUSIONS: Compared to the single cone technique, a more favourable root canal filling with less sealer could be expected from both warm obturation techniques in curved root canals. CLINICAL RELEVANCE: The easier-to-handle Guttafusion leads to comparable results as Thermafil in curved root canals.

The impact of loupes and microscopes on vision in endodontics.

AIM: To report on an intraradicular visual test in a simulated clinical setting under different optical conditions. METHODOLOGY: Miniaturized visual tests with E-optotypes (bar distance from 0.01 to 0.05 mm) were fixed inside the root canal system of an extracted maxillary molar at different locations: at the orifice, a depth of 5 mm and the apex. The tooth was mounted in a phantom head for a simulated clinical setting. Unaided vision was compared with Galilean loupes (2.5× magnification) with integrated light source and an operating microscope (6× magnification). The influence of the dentists' age within two groups was evaluated: <40 years (n = 9) and ≥40 years (n = 15). RESULTS: Some younger dentists were able to identify the E-optotypes at the orifice, but otherwise, natural vision did not reveal any measurable result. With Galilean loupes, the younger dentists <40 years could see a 0.05 mm structure at the root canal orifice, in contrast to the older group ≥40 years. Only the microscope allowed the observation of structures inside the root canal, independent of age. CONCLUSION: Unaided vision and Galilean loupes with an integrated light source could not provide any measurable vision inside the root canal, but younger dentists <40 years could detect with Galilean loupes a canal orifice corresponding to the tip of the smallest endodontic instruments. Dentists over 40 years of age were dependent on the microscope to inspect the root canal system.

Infiltration of natural caries lesions in relation to their activity status and acid pretreatment in vitro.

This study aimed at testing how active and inactive enamel caries lesions differ by their degree of resin infiltration, and whether the choice of acid pretreatment plays a crucial role. Four examiners assessed 104 human molars and premolars with noncavitated enamel lesions and classified them as 'active' or 'inactive' using the Nyvad criteria. Forty-five teeth were included in this study after independent unanimous lesion activity assessment. Lesions were cut perpendicularly into 2 halves. Each half lesion was pretreated with either 15% hydrochloric acid or 35% phosphoric acid. The lesions were infiltrated after staining with rhodamine isothiocyanate. Thin sections of 100 µm were prepared and the specimens were bleached with 30% hydrogen peroxide. The specimens were then counterstained with sodium fluorescein, subjected to confocal laser scanning microscopy and analyzed quantitatively. Outcome parameters were maximum and average infiltration depths as well as relative penetration depths and areas. In active lesions no significant difference of percentage maximum penetration depth and percentage average penetration depth between lesions pretreated with hydrochloric or phosphoric acid could be observed. In inactive lesions, however, phosphoric acid pretreatment resulted in significantly lower penetration compared to hydrochloric acid pretreatment. Surface conditioning with hydrochloric acid led to similar infiltration results in active and inactive lesions. Moreover, inactive lesions showed greater variability in all assessed infiltration parameters than did active lesions. In conclusion, caries lesion activity and acid pretreatment both influenced the infiltration. The use of phosphoric acid to increase permeability of the surface layer of active lesions should be further explored.

Evaluation of perpendicular reflection intensity for assessment of caries lesion activity/inactivity.

The aim of this study was to evaluate, using visual assessment, an experimental optical sensor measuring perpendicular reflection intensity (PRI) as an indicator of enamel caries lesion activity/inactivity. Forty teeth with either an active or an inactive enamel lesion were selected from a pool of extracted teeth. Each tooth was cut into halves, with a clinically sound half and a half with a non-cavitated enamel lesion. After gentle plaque removal, the teeth were kept moistened. The lesions were then photographed and a defined measuring site per lesion was chosen and indicated with an arrow on a printout. Independently, the chosen site was visually assessed for lesion activity, and its glossiness was measured with PRI assessment. Surface roughness (SR) was assessed with optical profilometry using a confocal microscope. Visual assessment and PRI were repeated after several weeks and a reliability analysis was performed. For enamel lesions visually scored as active versus inactive, significantly different values were obtained with both PRI and SR. PRI values of the clinically sound control surfaces were significantly different only from active lesions. Generally, inactive lesions had the same glossiness and the same roughness as the sound control surfaces. The reliabilities for visual assessment (κ = 0.89) and for PRI (ICC = 0.86) were high. It is concluded that, within the limits of this study, PRI can be regarded as a promising tool for quantitative enamel lesion activity assessment. There is scope and potential for the PRI device to be considerably improved for in vivo use.

Clinical performance of a new laser fluorescence device for detection of occlusal caries lesions in permanent molars.

OBJECTIVES: To determine the clinical performance of a laser fluorescence device (DIAGNOdent pen, KaVo) to discriminate between different occlusal caries depths (D(0)-D(1-4); D(0-2)-D(3,4)) in permanent molars. METHODS: In this prospective, randomized two-centre-study 120 sound/uncavitated carious sites in 120 patients were measured after visual and radiographic caries assessment. In cases of operative intervention (n=86), the lesion depths after caries removal were recorded (reference). In cases of preventive intervention (n=34), the sites were reassessed visually/radiographically after 12 months to verify the status assessed before (reference). The discrimination performance was determined statistically (Mann-Whitney test, Spearman's rho coefficient, and areas under the receiver operating characteristic curves (AUCs)). Sensitivities (SE) and specificities (SP) were plotted as a function of the measured values and cut-off values for the mentioned thresholds suggested. RESULTS: Sound sites (n=13) had significantly minor fluorescence values than carious sites (n=107) (P<0.0001) as had sites with no/enamel caries (n=63) compared to dentinal caries (n=57). The AUCs for the same discriminations were 0.92 and 0.78 (P<0.001). For the D(0)-D(1-4) threshold, a cut-off at a value of 12 (SE: 0.88, SP: 0.85) and for the D(0-2)-D(3,4) threshold at 25 (SE: 0.67, SP: 0.79) can be suggested. A moderate positive correlation between the measurements and the caries depths was calculated (rho=+0.57, P=0.01). CONCLUSION: Within this study, the device's discrimination performance for different caries depths was moderate to very good and it may be recommended as adjunct tool in the diagnosis of occlusal caries.

Integrated learning in dentistry: baseline data and first evaluation at the Dental School of Basel.

INTRODUCTION: Integrated learning modules were introduced and baseline information was collected, in order to identify the expectations regarding e-learning. Furthermore, first formative evaluation of fourth-year dental students was conducted and the experience gained with summative online assessment was reported. METHODS: Questionnaires designed by Infratest dimap (Berlin, Germany) were distributed to undergraduate students (n = 72) of the School of Dentistry. The fourth-year dental students went through a preliminary evaluation process. An online test was evaluated and compared with a traditional examination. RESULTS: Sixty-three questionnaires were returned. Sixty-five per cent of the students were already familiar with e-learning. All but one student owned at least one personal computer or laptop. Ninety-one per cent of the students expected positive effects from the integration of online modules. Enhanced flexibility regarding time and location as well as comfortable access to learning materials were mentioned most frequently. Ninety per cent of the students expected to achieve better results by finding it easier to understand learning materials produced with multimedia tools. Sixty per cent of the students feared technical complications when using an online platform. The online test was successfully performed. A formative evaluation process demonstrated agreement between expectations and first experiences with e-learning. CONCLUSIONS: Most students expect the quality of their studies to improve by implementation of e-learning. Students appreciating regularly updated learning materials particularly emphasise the importance of its visualisation. Online tests might be an option for student's self-performance rating.

A Near Visual Acuity Test for Dentists.

Unimpaired near vision is crucial in dentistry, but appropriate visual tests at dental working distance are not publicly available. The aim of this study was to validate a novel visual triage test for dentists that is easy to use and freely available. The near visual acuity at 300 mm of 106 dental professionals (aged 21-65 years) was assessed with 1) a validated near visual test for scientific purposes miniaturized on a microfilm; 2) an experimental test using a US $5 bill, in which the first five words of each line in the Lincoln Memorial frieze had to be read under a dental operating light. The Spearman rank correlation coefficient of 0.784 revealed a strong correlation between the two tests (p<0.0001). The ability to read six or more words in the memorial frieze meant there was a 94% chance of having a validated near visual acuity greater than or equal to the median score of the dentists tested. If none of the words could be read, the chance of having a near visual acuity below the median of the peer group was 89%. The influence of the dentists' age and experience on their visual performance reported in former studies was corroborated with this new test. The US $5 bill offers a simple and easily available near visual test to rank individuals' near vision relative to that of other dentists and to recognize the progression of presbyopia with increasing age.

Impact of different magnification levels on visual caries detection with ICDAS.

OBJECTIVES: The aim of this in vitro study was to examine the effect of different levels of magnification on the accuracy and reliability of visual caries detection using ICDAS criteria. METHODS: Occlusal surfaces of 100 extracted molars were assessed by 14 examiners (3rd and the 4th year dental students and dentists) using no magnification aids, a 2.5× Galilean loupe, a 4.5× Keplerian loupe, or a surgical microscope with 10× magnification. The assessments were repeated on a different day. Sensitivity, specificity, AUC and reliabilities were calculated according to the gold standard of histology. RESULTS: We found that with increasing magnification, the number of surfaces rated as "sound" (ICDAS code 0) decreased, while the number of surfaces with a localized enamel breakdown (ICDAS code 3) increased. While the sensitivities increased, the values of the specificities decreased to an unacceptably low level irrespective of the clinical experience of the examiners. CONCLUSIONS: ICDAS seems to be optimized for natural vision up to 2.0× magnification and not for high magnifications. The use of powerful magnification in visual caries detection involves the risk of unnecessary and premature invasive treatment. CLINICAL SIGNIFICANCE: This paper discusses when it does and does not make sense to use magnification devices for visual caries detection using ICDAS criteria. Strong magnifications should be refrained from for this purpose.

Detection of proximal secondary caries at cervical class II-amalgam restoration margins in vitro.

OBJECTIVES: To compare the performance of LFpen (DIAGNOdent pen) with two different wedge-shaped tips to conventional bitewing radiography (BW) for detecting proximal secondary caries at the cervical margin of amalgam restorations in vitro. METHODS: Seventy-five molars with class II amalgam restorations were selected. Depending on the marginal filling extension, data was subdivided into a crown group (C), when the filling ended in enamel, and into a root group (R), when the filling ended beyond the cementum-enamel junction. Bayesian analysis including calculation of the area under the receiver operating curve (AUC) was performed. Furthermore, Spearman correlations between caries and cofactors, such as presence of plaque or stain, occlusal ditching, marginal gap size, filling overhangs, and shortfalls, were calculated. Additionally, for group R the correlation coefficient between LFpen measurements and lesion depth was calculated. Histology served as gold standard. RESULTS: In group C both at the D1 and D3 levels, LFpen with two different tips showed a better performance than bitewing radiography (AUC at D1: 0.83/0.79 (LFpen) and 0.63 (BW); at D3: 0.66/0.66 (LFpen) and 0.53 (BW)). In group R, the respective AUC values were 0.53/0.56 (LF) and 0.59 (BW). A significant medium correlation was observed for occlusal ditching and proximal caries. Stain accumulation at the restoration margins especially in combination with filling overhangs interfered with LFpen readings, resulting in false positive measurements. CONCLUSIONS: Compared to BW, LFpen enhances the detection of secondary caries lesions at the cervical margin of amalgam restorations that do not extend below the cementum-enamel junction.

Preventing erosion with novel agents.

OBJECTIVES: This in vitro study aimed to investigate the protective effect of four commercial novel agents against erosion. METHODS: Ninety human molars were distributed into 9 groups, and after incubation in human saliva for 2 h, a pellicle was formed. Subsequently, the specimens were submitted to demineralization (orange juice, pH 3.6, 3 min) and remineralization (paste slurry containing one of the tested novel agents, 3 min) cycles, two times per day, for 4 days. The tested agents were: (1) DenShield Tooth; active ingredient: 7.5% W/W NovaMin(®) (calcium sodium phosphosilicate); (2) Nanosensitive hca; active ingredient: 7.5% W/W NovaMin(®); (3) GC Tooth Mousse; active ingredient: 10% Recaldent™ (CPP-ACP); (4) GC MI Paste Plus; active ingredients: 10% Recaldent™, 900 ppm fluoride. Two experimental procedures were performed: in procedure 1, the tested agents were applied prior to the erosive attack, and in procedure 2 after the erosive attack. A control group receiving no prophylactic treatment was included. Surface nanohardness (SNH) of enamel specimens was measured after pellicle formation and after completion of daily cyclic treatment. RESULTS: SNH significantly decreased at the end of the experiment for all groups (p<0.05). In both procedures, there was no statistically significant difference between the control group and those treated with paste slurries (p>0.05). In addition, the changes in SNH (ΔSNH=SNHbaseline-SNHfinal) did not show statistically significant difference between both procedures (p>0.05). CONCLUSION: Tooth erosion cannot be prevented or repaired by these novel agents, regardless of fluoride content.

In vivo performance of a laser fluorescence device for the approximal detection of caries in permanent molars.

OBJECTIVES: The aim of this randomised clinical trial was to investigate if a laser fluorescence device is able to discriminate between sound and carious approximal sites and between enamel and dentinal lesions, as well as to find appropriate cut-off values. METHODS: One hundred and seventeen sound or uncavitated carious sites in permanent molars were visually and radiographically examined, then either opened or not, after which their laser fluorescence was measured. Forty-three lesions were opened, the caries removed and the clinically identified caries depths were registered in addition to the radiographical scoring. Seventy-four sites were radiographically deemed sound or had enamel caries and were not opened. Here, the radiographical scorings were registered. RESULTS: Taking the radiographic scoring as gold standard for all investigated approximal sites, sound sites (D(0), n=40) showed significantly lower laser fluorescence measurements than carious sites (D(1-4), n=77) (Mann-Whitney test, P<0.025) suggesting a cut-off at 7 (sensitivity=0.68, specificity=0.7). Comparing measurements of D(0-2) (n=74) and D(3,4) (n=43), the results were also different by a statistically significant amount (P<0.025) and the cut-off calculated to be 16 (sensitivity=0.6, specificity=0.84). A fair positive correlation between laser fluorescence values and radiographical scoring was found (rho=+0.47, P<0.01). Analysing the 43 opened lesions with their clinically found lesion depths as gold standard, there was a fair positive correlation to the laser fluorescence values (rho=+0.34, P=0.03) and a moderately strong correlation to the radiographic scoring (rho=+0.67, P<0.01). CONCLUSION: The device may be an adjunct tool in the approximal detection of caries along with established procedures.

Traditional lesion detection aids.

Lesion detection aids ideally aim at increasing the sensitivity of visual caries detection without trading off too much in terms of specificity. The use of a dental probe (explorer), bitewing radiography and fibre-optic transillumination (FOTI) have long been recommended for this purpose. Today, probing of suspected lesions in the sense of checking the 'stickiness' is regarded as obsolete, since it achieves no gain of sensitivity and might cause irreversible tooth damage. Bitewing radiography helps to detect lesions that are otherwise hidden from visual examination, and it should therefore be applied to a new patient. The diagnostic performance of radiography at approximal and occlusal sites is different, as this relates to the 3-dimensional anatomy of the tooth at these sites. However, treatment decisions have to take more into account than just lesion extension. Bitewing radiography provides additional information for the decision-making process that mainly relies on the visual and clinical findings. FOTI is a quick and inexpensive method which can enhance visual examination of all tooth surfaces. Both radiography and FOTI can improve the sensitivity of caries detection, but require sufficient training and experience to interpret information correctly. Radiography also carries the burden of the risks and legislation associated with using ionizing radiation in a health setting and should be repeated at intervals guided by the individual patient's caries risk. Lesion detection aids can assist in the longitudinal monitoring of the behaviour of initial lesions.

Novel lesion detection aids.

Several non-invasive and novel aids for the detection of (and in some cases monitoring of) caries lesions have been introduced in the field of 'caries diagnostics' over the last 15 years. This chapter focusses on those available to dentists at the time of writing; continuing research is bound to lead to further developments in the coming years. Laser fluorescence is based on measurements of back-scattered fluorescence of a 655-nm light source. It enhances occlusal and (potentially) approximal lesion detection and enables semi-quantitative caries monitoring. Systematic reviews have identified false-positive results as a limitation. Quantitative light-induced fluorescence is another sensitive method to quantitatively detect and measure mineral loss both in enamel and some dentine lesions; again, the trade-offs with lower specificity when compared with clinical visual detection must be considered. Subtraction radiography is based on the principle of digitally superimposing two radiographs with exactly the same projection geometry. This method is applicable for approximal surfaces and occlusal caries involving dentine but is not yet widely available. Electrical caries measurements gather either site-specific or surface-specific information of teeth and tooth structure. Fixed-frequency devices perform best for occlusal dentine caries but the method has also shown promise for lesions in enamel and other tooth surfaces with multi-frequency approaches. All methods require further research and further validation in well-designed clinical trials. In the future, they could have useful applications in clinical practice as part of a personalized, comprehensive caries management system.