Richard Stoll

Effectiveness of four electronic apex locators to determine distance from the apical foramen

AIM To evaluate the accuracy of four electronic apex locators (EAL) in the apical region (0-3 mm short of the foramen) and to compare the precision of the readings on the display with the real position of the file in the root canal. METHODOLOGY Twenty single-rooted extracted teeth with round root canals were used. The canal orifices were preflared, and the length to the major foramen was determined visually under a microscope. Canals were enlarged, so that a size 15 file fitted well inside the canal. Teeth were mounted in acrylic test tubes filled with physiologic saline solution. Electronic length was determined in the region between the major foramen and 3 mm short of it in 0.5 mm steps with the Dentaport ZX, Root ZX mini, Elements Diagnostic Unit and Apex Locator and Raypex 5 using files of size 10 and size 15. The data were analysed using linear regression between true length and EAL reading, Bland-Altman plots and nonparametric tests at a significance level of alpha = 0.05. RESULTS The major foramen was detected by all EALs. With a measurement file positioned directly at the major foramen, meter readings were equivalent to a position 0.01-0.38 mm away. For the Dentaport ZX, a better accuracy using the size 15 file for the area 0-1.5 mm short of the apex was found. The differences in measurements between the two files were smaller for the other EALs. In linear regression, a good linearity for Dentaport ZX and Root ZX mini and moderate linearity for Elements Diagnostic Unit and Apex Locator and Raypex 5 were found. The slope of the measurement curve was too low (0.37-0.57) for the Raypex 5 and almost optimal for the Dentaport ZX (1.01-1.05). The Root ZX mini and the Elements Obturation Unit produced lower slope values and especially the Elements Obturation Unit revealed much higher SDs at the different measurement levels. CONCLUSION Amongst the four EALs, the Dentaport ZX and Root ZX mini had the best agreement between true lengths and meter readings. For the Raypex 5, an interpretation of the colour-coded zones as distance to the foramen cannot be recommended and might lead to erroneous interpretations.

Longevity of cast gold inlays and partial crowns--a retrospective study at a dental school clinic.

Abstract From 1963 to 1993, 890 patients were treated with 3518 cast gold restorations by students and postgraduate dentists. The longevity of these restorations was studied retrospectively using the patient files. Longevity was calculated using the method described by Kaplan and Meier. After the observation period, 111 (3.2%) of the examined restorations were not in place anymore. The most frequent reasons for failure were caries (33.7%), lack of retention (32.7%), endodontic treatment (29.6%), insufficient marginal adaptation (3.1%) and extraction (1%). The cumulative survival rate and a 95% interval of confidence was calculated for all restorations and for each of the locations and surfaces included in the trial. The 10-year survival rate for occlusal inlays was, 76.1% (12.1) for MO inlays 88.3% (4.2), for DO inlays 83.4% (4.6), for MOD inlays 87.5% (2.4), for partial crowns 86.1% (3.3) and 85.7% (1.7) for all restorations. Based on the statistical method used, the cast gold restorations demonstrated satisfactory longevity results.

Performance of laser fluorescence at tooth surface and histological section

This study aimed to evaluate a laser fluorescence device (the DIAGNOdent) and a visual classification system (ICDAS-II) for occlusal caries diagnosis. It also aimed to determine whether fluorescence measurements taken at the tooth surface correlate with the fluorescence measurements taken within the body of the lesion. The occlusal surfaces of 100 extracted permanent teeth were examined using ICDAS-II and DIAGNOdent (LF-tooth). Serial sections were made and lesion depth was assessed histologically. DIAGNOdent readings were also taken from the sections (LF-section). There were significant positive strong correlations between ICDAS-II and histology (rS = 0.71) and LF-section and histology (rS = 0.70), and only moderate correlations between LF-tooth and histology (rS = 0.51) and LF-tooth and LF-section (rS = 0.60). Diagnostic accuracy for ICDAS-II was generally better than for LF-tooth. While the DIAGNOdent device provides an objective reading for detection and monitoring of carious lesions, using the cut-off ranges previously suggested leads to inferior performance.

Performance of a fluorescence camera for detection of occlusal caries in vitro.

The aim of this study was to assess inter- and intra-examiner reproducibility and accuracy in the detection and assessment of occlusal caries in extracted human teeth using the newly developed fluorescence based camera VistaProof. Serial sectioning and microscopy are considered the gold standard. The occlusal surfaces of 53 teeth (99 investigation sites) were examined by two examiners with different levels of experience in cariology (one experienced dentist, one final-year dental student) and the VistaProof. Thereafter, the teeth were serially sectioned and assessed for lesion depth. The intraclass correlation coefficients for inter- and intra-examiner reproducibility for the fluorescence-based examinations were 0.76–0.95. There was a significant correlation between the fluorescence and histological examinations for both examiners (rs = 0.47 and 0.55, P < 0.01). At the D1 diagnostic threshold (enamel and dentin lesions), sensitivity was 0.71–0.86 and specificity was between 0.32 and 0.76 at different cutoff values. At the D3 diagnostic threshold (dentin lesions), sensitivity was 0.04–0.91 and specificity was 0.56–0.99 for both examiners. When the areas under the receiver-operating characteristic curves were compared, there was no significant difference in the performance between the examiners (P = 0.52 at the D1 threshold, P = 0.81 at the D3 threshold). The VistaProof demonstrated high reproducibility and good diagnostic performance for the detection of occlusal caries at various stages of the disease process. Novice and experienced examiners were able to apply this system as a supportive device for caries diagnostic and monitoring purposes. Sensitivity and specificity values varied depending on the cutoff values.

Effect of Different Time Intervals between Examinations on the Reproducibility of ICDAS-II for Occlusal Caries

Aim: To evaluate intra- and interexaminer reproducibility of ICDAS-II on occlusal caries diagnosis when different time intervals were allowed to elapse between examinations. A subsidiary aim was to determine whether collapsing the codes would influence this reproducibility. Methods: The occlusal surfaces of 50 permanent posterior teeth were investigated by 3 trained examiners using ICDAS-II at baseline, 1 day, 1 week and 4 weeks after baseline. Results: Weighted kappa values for intra- and interexaminer reproducibility were 0.76–0.93. Conclusion: The time span did not have a major impact on assessing intra- and interexaminer reproducibility. Collapsing ICDAS-II codes had no impact on examiner reproducibility.

Impact of Scoring Single or Multiple Occlusal Lesions on Estimates of Diagnostic Accuracy of the Visual ICDAS-II System.

Carious lesions can occur at different sites on the occlusal surfaces of teeth and may differ in appearance and severity. This study aimed to evaluate how estimates of reproducibility and accuracy of ICDAS-II were affected when all lesions on occlusal surfaces, or only a representative lesion, were scored. 100 permanent teeth with 1–4 investigation sites on the occlusal surface were examined visually by four examiners. Serial sections of the teeth were assessed for lesion depth. Intra- and interexaminer reproducibility (weighted kappa values), sensitivity, and specificity were calculated for all investigation sites and for a randomly selected site per tooth. Comparing the kappa values for the whole sample and the independent sites, no effect or only a small effect was found. Comparing the areas under the ROC-curves no effect could be shown. Examining multiple sites on teeth leads to results comparable to when a single independent site is chosen per tooth.

Impact of measuring multiple or single occlusal lesions on estimates of diagnostic accuracy using fluorescence methods

Carious lesions can occur at different sites on the occlusal surfaces of teeth and may differ in appearance and severity. This study aimed to evaluate how scoring several lesions on occlusal surfaces, as opposed to only one representative lesion, affects estimates of reproducibility and accuracy of fluorescence-based devices. Thirty-six permanent teeth with 2-3 investigation sites (n = 82) were examined by two examiners using the laser fluorescence device DIAGNOdent pen (LF) and the fluorescence camera VistaProof (FC). Lesion depth was then assessed histologically in serial sections of the teeth. Intra-class-correlation coefficients (ICC) and areas under the ROC-curves were calculated for all investigation sites and for one randomly selected site per tooth. Comparing the reproducibility and the performance for the whole sample and the independent sites showed only a small effect or no effect. Measuring multiple sites on teeth with fluorescence devices only moderately influences performance compared to one site being investigated.

Survival of Inlays and Partial Crowns Made of IPS Empress After a 10-year Observation Period and in Relation to Various Treatment Parameters

UNLABELLED This study evaluated the long-term survival of inlays and partial crowns made of IPS Empress. For this purpose, the patient data of a prospective study were examined in retrospect and statistically evaluated. MATERIALS AND METHODS All of the inlays and partial crowns fabricated of IPS-Empress within the Department of Operative Dentistry at the School of Dental Medicine of Philipps University, Marburg, Germany were systematically recorded in a database between 1991 and 2001. The corresponding patient files were revised at the end of 2001. The information gathered in this way was used to evaluate the survival of the restorations using the method described by Kaplan and Meyer. RESULTS A total of n = 1624 restorations were fabricated of IPS-Empress within the observation period. During this time, n = 53 failures were recorded. The remaining restorations were observed for a mean period of 18.77 months. The failures were mainly attributed to fractures, endodontic problems and cementation errors. The last failure was established after 82 months. At this stage, a cumulative survival probability of p = 0.81 was registered with a standard error of 0.04. At this time, n = 30 restorations were still being observed. Restorations on vital teeth (n = 1588) showed 46 failures, with a cumulative survival probability of p = 0.82. Restorations performed on non-vital teeth (n = 36) showed seven failures, with a cumulative survival probability of p = 0.53. Highly significant differences were found between the two groups (p < 0.0001) in a log-rank test. No significant difference (p = 0.41) was found between the patients treated by students (n = 909) and those treated by qualified dentists (n = 715). Likewise, no difference (p = 0.13) was established between the restorations seated with a high viscosity cement (n = 295) and those placed with a low viscosity cement (n = 1329).

Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes.

This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (Ra) and maximum roughness (Rz) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p>0.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p>0.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving Ra=0.21±0.03µm and Rz=1.73±0.04µm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality.

Adhesion of self-adhesive root canal sealers on gutta-percha and Resilon

INTRODUCTION The aim of this study was to evaluate the bond strength of different adhesive sealers on Resilon and gutta-percha. METHODS Pellets of gutta-percha and Resilon were embedded into test tubes. Small eyelets were attached to those surfaces with a 0.5-mm film of different root canal sealers. Real Seal, Real Seal SE, Hybrid Root Seal (also known as Meta Seal), and AH Plus were used. AH Plus as a nonadhesive sealer served as a control group. In all groups (n = 10) shear bond strength was measured. RESULTS Shear bond strength was relatively low (0.1-3 MPa) and significantly higher in the groups with a single component adhesive sealer. No substantial bond strength was found in the control group. Overall bond strength to Resilon was higher than to gutta-percha but not significant compared with the Hybrid Root Seal group. CONCLUSIONS With single component self-adhesive sealers, an adhesive connection might be formed to gutta-percha as well as to Resilon.