Matthias J. Roggendorf

Marginal quality of flowable 4-mm base vs. conventionally layered resin composite

OBJECTIVE This study evaluated marginal integrity of bonded posterior resin composite fillings to enamel and dentine with and without 4mm flowable base, before and after thermo-mechanical loading (TML). METHODS 80 MOD cavities with one proximal box beneath the CEJ were prepared in extracted human third molars. Direct resin composite restorations (SDR with CeramX mono, Tetric EvoCeram, Filtek Supreme XT, and Venus Diamond or the respective resin composites alone) were bonded with system immanent adhesives XP Bond, Xeno V, Syntac, Adper Prompt L-Pop, and iBond self-etch. Before and after thermomechanical loading (100,000×50N, 2500 thermocycles between 5 and 55°C), marginal gaps were analysed using SEM of epoxy resin replicas. Results were analysed with Kruskal-Wallis and Mann-Whitney U-tests (p<0.05). After thermomechanical loading, specimens were cut longitudinally in order to investigate internal dentine adaptation by epoxy replicas under a SEM (200× magnification). RESULTS In enamel, high percentages of gap-free margins were initially identified for all adhesives. After TML, etch-and-rinse adhesives performed better than self-etch adhesives (p<0.05). Also in dentine, initially high percentages of gap-free margins were found for all adhesives. After TML, etch-and-rinse adhesives again performed better than self-etch adhesives for both marginal and internal adaptation (p<0.05). The presence of a 4mm layer of SDR had no negative influence on results in any group (p>0.05). CONCLUSIONS SDR as 4mm bulk fill dentine replacement showed an good performance with the material combinations under investigation.

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.

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.

Bond Strength of Adhesive Cements to Root Canal Dentin Tested with a Novel Pull-out Approach

INTRODUCTION A novel approach to the pull-out test using silica-coated and silanized steel spreaders was designed to avoid influence from the post-cement interface. In this study, this test was applied to compare the post retention of adhesive versus conventional cements. METHODS Canals of 90 single-rooted human teeth were prepared to size 60 taper .02; trimmed to an 8-mm root canal length; irrigated with 40% citric acid, 3% NaOCl, and 70% ethanol; and randomly divided into 9 groups (n = 10). Steel spreaders (size 55, taper .02) were silica coated and silanized with the Rocatec system (3M-Espe, Seefeld, Germany), except for a control group using GCem, and cemented with one of these adhesive luting materials (RelyX Unicem [3M-Espe], Clearfil SA Cement [Kuraray Medical, Okayama, Japan], Bifix SE [Voco GmbH, Cuxhaven, Germany], NX3 [Kerr, Orange, CA], GCem [GC Corp, Tokyo, Japan], or SmartCem2 [Dentsply De Trey GmbH, Konstanz, Germany]) or conventional cements (Hoffmanns cement [Hoffmann Dental Manufaktur GmbH, Berlin, Germany] or Ketac Cem [3M-Espe]). After storage in distilled water (24 h/37°C), the spreaders were pulled out in a universal testing machine at a crosshead speed of 2 mm/min. RESULTS The failure mode was cohesive or adhesive at the cement-dentin interface in more than 80% of the experimental samples (control group: adhesive to the post: 9/10 samples). Adhesive luting materials retained posts better than conventional cements (t test, P < .001) but with a wide range in variation. RelyX Unicem displayed significantly higher values except when compared with Bifix SE and Clearfil SA (analysis of variance/Student-Newman-Keuls, P < .05). NX3, SmartCem2, and GCem showed no significant differences to Hoffmanns cement and Ketac Cem. CONCLUSIONS The novel pull-out approach served well in testing the bond strength of different cements to root canal dentin. The bonding effectiveness of adhesive cements varied significantly and was material specific.

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.

Effect of proximal box elevation with resin composite on marginal quality of resin composite inlays in vitro

OBJECTIVES To evaluate marginal quality and resin-resin transition of lab made resin composite inlays in deep proximal cavities with and without 3 mm proximal box elevation (PBE) using resin composites before and after thermo-mechanical loading (TML). METHODS MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 40 extracted human third molars. Proximal boxes ending in dentine were elevated 3 mm with different resin composites (G-Cem, Maxcem Elite as self-adhesive resin cements and Clearfil Majesty Posterior as restorative resin composite in one or three layers bonded with AdheSE), or left untreated. Clearfil Majesty Posterior inlays were luted with Syntac and Variolink II (n = 8). Marginal quality as well as the PBE-composite inlay interface was analyzed under an SEM using epoxy resin replicas before and after thermomechanical loading (100,000 × 50 N and 2500 thermocylces between +5 °C and +55 °C). RESULTS Bonding resin composite inlays directly to dentine showed similar amounts of gap-free margins in dentine compared to PBE applied in three consecutive layers (p > 0.05). The groups with self-adhesive resin cements for PBE exhibited significantly more gaps in dentine (p < 0.05). SIGNIFICANCES With layered resin composite, PBE is effective in indirect resin composite bonding to deep proximal boxes. Self-adhesive resin cements are not suitable for this indication.

Retrospective Evaluation of Perforation Repairs in 6 Private Practices

INTRODUCTION The purpose of this study was to investigate retrospectively the clinical outcome of 70 perforation repairs performed by 6 endodontic specialists. METHODS Endodontic specialists performed a total of 70 perforation repairs (69 patients) between 1998 and 2010 using a nonsurgical or combined nonsurgical/surgical approach. Treatments were performed with the aid of a dental operating microscope. Recalls of at least 6 months were obtained on 49 patients (50 teeth). Two calibrated observers evaluated the radiographic results on recalls up to 116 months, with a mean of 37 months. Pre-, intra-, and postoperative data were evaluated with respect to treatment outcomes and possible prognostic factors. RESULTS Successful results were obtained in 45 of 50 perforation repairs, a success rate of 90%. Significant prognostic factors included the location of the perforation, sex of the patient, and restorative status of the tooth before perforation repair. The overall success rate of this study was higher than reported in other studies. CONCLUSIONS Perforation repairs can be performed with a high level of success at least in the short- to medium-term.

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.

Chairside vs. labside ceramic inlays: Effect of temporary restoration and adhesive luting on enamel cracks and marginal integrity

OBJECTIVES To assess the influence of different temporary restorations and luting techniques of labside and chairside ceramic inlays on enamel defects and marginal integrity. METHODS 120 extracted human third molars received MOD preparations with one proximal box each limited in either enamel or dentin. 64 Cerec 2 inlays and 56 IPS Empress I inlays were randomly assigned to the following groups (fabrication mode: chairside (CS)=no temporary restoration (TR), labside (LS)=TR with Luxatemp (L) inserted with TempBond NE, or Systemp.inlay (SI) without temporary cement), luting technique: SV=Syntac/Variolink II, RX=RelyX Unicem: A: Cerec inlays were luted with (1) CS/SV. (2) CS/SV/Heliobond separately light-cured. (3) CS/RX. (4) LS/L/SV. (5) LS/L/RX. (6) LS/SI/SV. (7) LS/SI/RX. (8) LS/SI/RX with selective enamel etching. B: Empress. (9) L/SV. (10) L/SV/Heliobond separately light-cured. (11) L/RX. (12) SI/SV. (13) SI/SV, Heliobond separately lightcured. (14) SI/RX. (15) SI/RX after selective enamel etching. Before and after thermomechanical loading (TML: loading time of TR 1000×50N+25 thermocycles (TC) between +5°C and +55°C; clinical simulation: 100,000×50N+2500 TC) luting gaps, enamel cracks, and marginal adaptation to enamel and dentin were determined under an SEM microscope (200×) using replicas. RESULTS Loading time of temporary restorations negatively affected enamel integrity and enamel chipping (p<0.05). Luxatemp resulted in less enamel cracks than Systemp.inlay (p<0.05). Syntac/Variolink achieved better marginal enamel quality than RelyX Unicem in all groups (p<0.05). Marginal quality in dentin revealed no differences when no temporary cement was used (p>0.05). Temporary cement negatively affected dentin margins when RelyX Unicem was used (p<0.05). SIGNIFICANCE Chairside-fabricated Cerec inlays reduce the risk of enamel cracks and marginal enamel chipping due to omitted temporary restorations. Syntac/Variolink revealed a significantly better performance than RelyX Unicem.

Stability of endodontically treated teeth with differently invasive restorations: Adhesive vs. non-adhesive cusp stabilization.

OBJECTIVES Aim of the present study was to evaluate fracture strength of endodontically treated molars with different preparations/restorations after thermomechanical loading in vitro. METHODS 264 extracted human third molars were used. Beside the control group, 256 teeth in 32 test groups (n=8) received root canal treatment (MTwo #40/.6) and root canal obturation with AH Plus and Guttapercha. After postendodontic sealing and build-up (Syntac, SDR), specimens were additionally prepared MO or MOD. Postendodontic restorations were: Direct restorations (Tetric EvoCeram Bulk Fill bonded with Syntac; as filling or direct partial crown (PC) after reducing the cusps 3mm; amalgam as filling or direct pin-retained partial crown (PC)), vs. indirect adhesive restorations (I: Inlay vs. PC; IPS Empress I/PC; Celtra Duo I/PC; e.max CAD I/PC; Lava Ultimate I/PC; Enamic I/PC - all inserted with Syntac/Variolink) vs. cemented cast gold I/PC. After 300,000 thermocycles (5/55°C) and 1.2 Mio. 100N load cycles, specimens were loaded until fracture. RESULTS Whereas IPS Empress showed no difference between I and PC (p>0.05), in all other groups PC were significantly more stable than fillings/inlays (p<0.05), this effect was more pronounced after MOD preparations. Cast gold PC exhibited the highest fracture strengths (p<0.05), inlays the lowest (p<0.05). IPS Empress was generally inferior to the other bonded materials under investigation (p<0.05) which as PC almost reached the level of control specimens. Amalgam fillings showed the worst outcome (p<0.05). SIGNIFICANCES Less invasive preparation designs were not beneficial for the stability of postendodontic restorations. Except for IPS Empress, PC were generally more successful in restabilization of weakened cusps after endodontic treatment and preparation. Cast gold PC remain the ultimate stabilization tool for ETT in terms of fracture resistance.