Influence of resin-coating techniques on the marginal adaptation and the bond strengths of CAD/CAM-fabricated hybrid ceramic inlays.

This study aimed to evaluate the effects of different resin-coating technique strategies and dual-cure resin luting materials on proximal marginal adaptation and the microtensile bond strengths (µTBSs) of CAD/CAM hybrid ceramic inlays. Extracted human molars were classified into four groups, depending on the coating technique: No coating (None), single coating (1-coating), double coating (2-coating), and flowable resin-coating (Combination). The inlays were bonded with one of the three materials: Panavia V5 (V5), Rely X Ultimate (RXU), and Calibra Ceram (CC). The differences with regard to adaptation were not significant. In the case of µTBS data for V5, no significant differences were observed, whereas for RXU, µTBS values for Combination statistically exceeded those for None and 1-coating. For CC, µTBS values for Combination statistically exceeded those for None, 1-coating, and 2-coating. The coating techniques did not influence the adaptation but influenced the bond strength, and Combination performed the best.

Proximal Caries Detection Using Short-Wave Infrared Transillumination at Wavelengths of 1050, 1200 and 1300 nm in Permanent Posterior Human Teeth.

This in vitro study aimed to investigate the diagnostic potential of short-wave infrared transillumination (SWIRT) at 1050, 1200 and 1300 nm for the detection of proximal caries in molars and premolars. It was compared to the diagnostic performance of bitewing radiography (BWR) and micro-computed tomography (µCT) as the reference standard. 250 sound or decayed proximal surfaces of permanent posterior extracted teeth were examined using (1) SWIRT at 1050, 1200 and 1300 nm with two camera systems of different resolutions, (2) BWR and (3) µCT. Thresholds were defined for both test methods and the reference standard for caries in general, enamel caries and dentin caries. All images were assessed by two examiners twice, at an interval of two weeks. SWIRT at wavelengths of 1050, 1200 and 1300 nm achieved sensitivity values more than 2.5 times higher than BWR (enamel caries 3.2-4.4 times; dentin caries 3.25-4.25 times) for the detection of proximal caries. Sensitivity values of SWIRT improved with the higher wavelength. No significant difference was found in diagnostic quality between the two camera systems. SWIRT at 1300 nm imaged proximal enamel caries with the highest accuracy, while the physical optimum for transillumination in dentin was located at a lower wavelength (<1000 nm).

Simulating the shrinkage-induced interfacial damage around Class I composite resin restorations with damage mechanics.

OBJECTIVES: To investigate the shrinkage-induced damage at the composite-tooth interface by finite element analysis (FEA) using the cohesive zone model (CZM). METHODS: Axisymmetric models of Class I restorations were created to illustrate the interfacial damage around composite resin restorations of different dimensions, with polymerization shrinkage modeled analogously to thermal shrinkage. The damage to the adhesive interface was determined using a CZM based on the fracture strength and fracture energy. To show the effects of damage, conventional models with perfectly bonded composite resin restorations were created as controls. RESULTS: The results indicated interfacial damage at the butt-joint cavosurface margin, dentinoenamel junction, and internal line angle. The percentage of damaged interfacial area was found to increase with decreasing diameter for restorations of the same height. For a given diameter, the damage was more severe for restorations of greater depth. The effects of the damage were further illustrated in the model with a restoration of 2-mm diameter and height. The interfacial damage occurred primarily at the internal line angle (83.3 % of all the damaged interfacial area), leading to local stress relief (from 18.3 MPa to 12.8 MPa), but also higher stress at the damage fronts. Greater local shrinkage was found in composites adjacent to the damage. SIGNIFICANCE: The damage mechanics-based CZM is an essential refinement of the FEA to predict interfacial damage and its implications. The extent of damage was found to be greater around restorations with smaller diameters and greater depths. The entire simulation is available via an open-source platform to facilitate further applications in adhesive dentistry.

Tooth whitening with an experimental toothpaste containing hydroxyapatite nanoparticles.

BACKGROUND: The aim of this study was to evaluate the postbrushing tooth-whitening effect of toothpaste containing hydroxyapatite nanoparticles (nano-HAPs). The impact of the concentration on the whitening performance of nano-HAP toothpaste was also investigated. METHODS: Two concentrations of nano-HAP (10 wt% and 1 wt%) were incorporated in nonabrasive toothpastes. Forty bovine incisors were randomly assigned into four groups: 10 wt% nano-HAP, 1 wt% nano-HAP, toothpaste without nano-HAP as a negative control and water as a blank control. Each tooth was treated with the toothpaste three times and hydrodynamic shear force (HSF) once. The teeth surfaces were observed by SEM after each application. Tooth color (L*, a* and b* values) was measured by a spectrophotometer, and color changes (△E, △L, △a and △b values) were calculated. Two-way mixed ANOVA was performed to evaluate the influence of the concentration and repeated application on the tooth-whitening effect of nano-HAP. RESULTS: We found that nano-HAP-treated enamel exhibited higher L* values and lower a* and b* values than the control groups (P < 0.05). The 10 wt% nano-HAP group showed significantly higher △E values than the 1 wt% nano-HAP group (P < 0.05). After three applications, the △E mean value of the 10 wt% nano-HAP group was 4.47. The △E and △L values were slightly reduced after HSF (P < 0.05). For both nano-HAP groups, HAP single crystallites and agglomerates were identified, and their sizes grew with nano-HAP reapplication. CONCLUSIONS: In conclusion, nano-HAP toothpaste has a satisfying postbrushing whitening effect and good resistance to mechanical forces. The whitening effect seemed to be concentration-dependent.

Attenuation of near-ultraviolet, visible and near-infrared light in sound and carious human enamel and dentin.

OBJECTIVES: This in vitro study aimed to investigate the optical attenuation of light at 405, 660 and 780 nm sent through sound and carious human enamel and dentin, including respective individual caries zones, as well as microscopically sound-appearing tissue close to a carious lesion. MATERIALS AND METHODS: Collimated light transmission through sections of 1000-125-µm thickness was measured and used to calculate the attenuation coefficient (AC). The data were statistically analysed with a MANOVA and Tukey's HSD. Precise definition of measurement points enabled separate analysis within the microstructure of lesions: the outer and inner halves of enamel (D1, D2), the translucent zone (TZ) within dentin lesions and its adjacent layers, the enamel side of the translucent zone (ESTZ) and the pulpal side of the translucent zone (PSTZ). RESULTS: The TZ could be distinguished from its adjacent layers and from caries-free dentin at 125 µm. Sound-appearing dentin close to caries lesions significantly differed from caries-free dentin at 125 µm. While sound and carious enamel exhibited a significant difference (p < 0.05), this result was not found for D1 and D2 enamel lesions (p > 0.05). At 405 nm, no difference was found between sound and carious dentin (p > 0.05). CONCLUSIONS: Light optical means enable the distinction between sound and carious tissue and to identify the microstructure of dentin caries partially as well as the presence of tertiary dentin formation. Information on sample thickness is indispensable when interpreting the AC. CLINICAL RELEVANCE: Non-ionising light sources may be suitable to detect lesion progression and tertiary dentin.

Adhesion and whitening efficacy of P11-4 self-assembling peptide and HAP suspension after using NaOCl as a pre-treatment agent.

BACKGROUND: This study evaluated the adhesion and whitening efficacy of a mixture of hydroxyapatite and P11-4 self-assembling peptide (HAP-peptide) on bovine enamel after pre-treatment with low-concentrated sodium hypochlorite (NaOCl). METHODS: Fifty-two caries-free bovine incisors were selected. 50 teeth were randomly allocated to five groups (n = 10). The first group was treated with a mixture of 6.25 wt% HAP and 5 ml P11-4 peptide, using NaOCl 3% as pre-treatment. Second, third and fourth groups were treated with 6.25 wt% HAP, 5 ml P11-4 peptide, and NaOCl 3%, respectively. In the fifth group, only water was applied (control group). The color of samples was measured using a spectrophotometer (USB4000-VIS-NIR-ES, Ostfildern, Germany). To evaluate color changes, ΔE values were statistically analyzed. Finally, adherence of HAP particles on two enamel surfaces with and without pre-treatment with NaOCl was analyzed with SEM. RESULTS: It was observed that the ΔE of the HAP-peptide suspension after pre-treatment with NaOCl was significantly stronger than the control group. In contrast, the overall color changes of separate applications of HAP, peptide, and NaOCl did not differ notably from the control group. SEM observations confirmed that pre-treatment with NaOCl resulted in a more pronounced coverage of HAP on the enamel surface. CONCLUSIONS: Pre-treatment with a low-concentrated NaOCl enhanced the adherence of the HAP layer on the enamel surface, resulting in a stronger whitening effect. TRIAL REGISTRATION: The peptide-HAP suspension is effective in improving tooth whiteness.

Influence of the preparation design on the survival probability of occlusal veneers.

OBJECTIVES: The fracture resistance of ultrathin computer-aided design and computer-aided manufacturing (CAD/CAM) occlusal veneers with different preparation designs was investigated under cycling mechanical loading and via finite element analysis (FEA). METHODS: Eighty molars were prepared with a circular enamel ring until complete exposure of the occlusal dentin occurred. Forty were prepared via additional circular chamfer preparation. The teeth were restored with 0.5 mm-thick occlusal veneers. Each group received a CAD/CAM fabricated occlusal veneer with a low modulus of elasticity (composite, CeraSmart) and a high modulus of elasticity material (ceramic, Celtra Duo). The restorations were adhesively luted and underwent 2000 thermocycling cycles. The samples were loaded at 50 N under 1,000,000 cycles in a chewing simulator and were checked for failure after various cycles. A visible crack was defined as failure, and the Kaplan-Meier survival rate was used for data analysis. One sample per group was digitized using microcomputed tomography, and FEA was performed using open-source software. The comparative stresses were analyzed for specimens with and without chamfer preparation. RESULTS: The survival probabilities were 60% for occlusal ceramic veneers without preparation and 40% for veneers with chamfer preparation, with no statistically significant differences. Composite veneers achieved 95% survival probability regardless of the preparation method. The main principal stress in ceramic restoration was visualized via FEA. In composite veneers, stress was also visible in the luting composite and dentin. SIGNIFICANCE: The preparation method had no influence on mechanical fatigue. Minimally invasive preparation can be recommended. The restoration material is crucial for survival.

Diagnostic validity of early proximal caries detection using near-infrared imaging technology on 3D range data of posterior teeth.

OBJECTIVES: This in vitro study analysed potential of early proximal caries detection using 3D range data of teeth consisting of near-infrared reflection images at 850 nm (NIRR). MATERIALS AND METHODS: Two hundred fifty healthy and carious permanent human teeth were arranged pairwise, examined with bitewing radiography (BWR) and NIRR and validated with micro-computed tomography. NIRR findings were evaluated from buccal, lingual and occlusal (trilateral) views according to yes/no decisions about presence of caries. Reliability assessments included kappa statistics and revealed high agreement for both methods. Statistical analysis included cross tabulation and calculation of sensitivity, specificity and AUC. RESULTS: Underestimation of caries was 24.8% for NIRR and 26.4% for BWR. Overestimation was 10.4% for occlusal NIRR and 0% for BWR. Trilateral NIRR had overall accuracy of 64.8%, overestimation of 15.6% and underestimation of 19.6%. NIRR and BWR showed high specificity and low sensitivity for proximal caries detection. CONCLUSIONS: NIRR achieved diagnostic results comparable to BWR. Trilateral NIRR assessments overestimated presence of proximal caries, revealing stronger sensitivity for initial caries detection than BWR. CLINICAL RELEVANCE: NIRR provided valid complement to BWR as diagnostic instrument. Investigation from multiple angles did not substantially improve proximal caries detection with NIRR.

Effects of application method on shrinkage vectors and volumetric shrinkage of bulk-fill composites in class-II restorations.

OBJECTIVES: Upon initial proximal wall construction, the favorable C-factor of class-II cavities may become unfavorable. This study investigated the application method on bulk-fill resin composite polymerization shrinkage. METHODS: Occluso-proximal class-II cavities were prepared in 40 molars and bonded with a self-etch adhesive (Adhese Universal). The study groups varied according to the resin composite application: group-1: bulk application, Tetric EvoCeram Bulk Fill (TBF); group-2: proximal wall construction (TBF) and occlusal cavity filling (TBF); group-3: thin flowable liner layer, Tetric EvoFlow Bulk Fill (TEF) and bulk filling (TBF); group-4: flowable liner (TEF), proximal wall (TBF), occlusal cavity (TBF); and group-5: bulk application, SDR (3 mm) and capping layer (TBF, 1 mm). Each resin composite increment was scanned twice using micro-CT (uncured, cured 40 s) at a resolution of 16 µm. Shrinkage vectors and volumetric polymerization shrinkage were evaluated and statistically analyzed (one-way ANOVA). SEM images were used to investigate the tooth-restoration interface. RESULTS: Shrinkage vectors differed significantly among the groups and were greatest in gp5-fl/SDR (47.6 µm), followed by gp1-TBF (23.8 µm) and least in gp5-fl/SDR+TBF (11.1 µm). Volumetric shrinkage varied significantly with the use of SDR (gp5-fl/SDR: 2.6%) and TEF (gp4-fl/TEF: 2.5%) to TBF (gp4-fl/TEF+wl/TBF: 0.6%) in the incremental application. SIGNIFICANCE: Building a proximal resin composite wall yielded smaller shrinkage vectors than the bulk application. Applying a thin flowable liner decreased the shrinkage vectors, even more when building a proximal wall. A thin flowable liner is recommended when building a proximal resin composite wall.

Bulk-fill Composites Compared to a Nanohybrid Composite in Class-II Cavities - A Two-year Follow-Up Study.

PURPOSE: To compare different concepts of direct composite restorations in class-II cavities using bulk-fill composites and a conventional composite with different layer thicknesses in a clinical study over a period of 2 years. MATERIALS AND METHODS: A low-viscosity (SDR), a high-viscosity bulk-fill (Tetric EvoCeram Bulk Fill) and a conventional nanohybrid composite (Tetric EvoCeram) were randomly assigned and placed in different layer thicknesses up to 4 mm in 160 class-II cavities in 94 patients. Restorations were clinically examined at baseline (n = 160), after 12 (n = 150) and 24 months (n = 148) and evaluated according to eight selected FDI criteria. In case of complete loss of the restoration or irreversible pulpitic symptoms, the restoration was rated as failure; repair was considered as relative failure. RESULTS: The materials investigated showed no significant differences regarding the FDI scores and failure rate during the entire follow-up. After 12 months, 7 failures and after 24 months a total of 8 failures were observed. After 2 years, Tetric EvoCeram Bulk Fill with a 4-mm layer thickness and SDR in combination with Tetric EvoCeram Bulk Fill with a 2-mm layer thickness exhibited a non-significant tendency towards increased hypersensitivity (FDI score 5) as compared to the reference material Tetric EvoCeram with a 2-mm layer thickness (p = 0.051; Kruskal-Wallis test). CONCLUSION: The clinical stability of bulk-fill materials in layers up to 4 mm is comparable to nanohybrid composites after 2 years.

Three-body wear of luting composites and influence of the ACTA wheel material.

The aim of the study was to investigate the wear of luting materials (Variolink Esthetic LC/DC, Multilink Automix, Panavia V5 paste) compared to a resin composite (Tetric EvoFlow) with an ACTA-machine (three-body-wear simulator) using steel and 3D-printed polymer wheels. Wear was measured (software Match3D) and statistically analyzed (ANOVA). Worn surface was examined with a field-emission-scanning-electron-microscope. Finite element analysis was carried out to analyze differences in the mechanical stress of the two different sample wheels. Using the steel wheel, Variolink Esthetic DC exhibited significantly less wear than Tetric EvoFlow after 200,000 cycles (p=0.037). Luting composites on polymer wheels exhibited significantly lower wear values compared to the steel wheels (p<0.001). Finite element analysis showed higher stresses for the steel wheel compared to the polymer wheel. Mechanical properties of the sample wheels had a high influence on wear properties. Dual- or auto-polymerizing materials seem to have a small advantage over the light-curing materials.

Near-infrared reflection at 780 nm for detection of early proximal caries in posterior permanent teeth in vitro.

OBJECTIVES: The aim of this in vitro study was to evaluate the diagnostic potential of near-infrared reflection at 780 nm (NIRR780nm) for early proximal caries detection on the occlusal, buccal and oral surfaces of molars and premolars under simulated, clinically relevant conditions. The findings were validated by micro-computed tomography (µCT). METHODS: Bitewing radiography (BWR) was used as a comparative diagnostic method. 250 sound or decayed permanent teeth were examined using NIRR780nm and BWR. The NIRR780nm findings were evaluated using yes/no decisions depending on the presence of caries lesions, as the enamel-dentin junction was not detectable in the majority of samples. All NIRR780nm, BWR and µCT findings were obtained twice by two trained examiners. NIRR780nm images were evaluated both occlusally alone and combined occlusally, lingually and buccally. All findings were presented in a cross-table. Sensitivity, specificity and area under the curve (AUC) values were calculated. Reliability assessment was performed using κ statistics. RESULTS: Underestimation of caries was observed for NIRR780nm in 26.0% of all surfaces and for BWR in 32.8% of all surfaces. Overestimation was 10.0% for NIRR780nm and 0.4% for BWR. Trilateral NIRR780nm assessment exhibited an overall accuracy of 67.2 %, an underestimation of 13.6% and an overestimation of 19.2%. Trilateral NIRR780nm exhibited 63.0% sensitivity and 69.6% specificity, while BWR exhibited 26.7% sensitivity but 100% specificity for proximal caries detection. CONCLUSION: NIRR780nm is not suitable for reliable detection of early proximal caries, even with the application of an ideal setup and optimized in vitro conditions.

In vitro comparison of two types of digital X-ray sensors for proximal caries detection validated by micro-computed tomography.

OBJECTIVES: We aimed to compare the diagnostic accuracy of two intraoral digital X-ray sensors-the charged-coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS)-for proximal caries detection in permanent molar and premolar teeth. Micro-CT served as the reference standard. METHODS: 250 samples were mounted in three-dimensional (3D)-printed phantoms, and their proximal surfaces were evaluated by ICDAS criteria directly to create a balanced sample. Bitewing radiography was conducted using 3D-constructed X-ray phantoms with a CCD sensor at a 0.08 s and a CMOS sensor at 0.12 and 0.16 s exposure time. Two examiners determined the diagnostic decisions twice at appropriate intervals. Three diagnostic thresholds for sound surfaces and enamel and dentin caries were defined and presented in a cross-table. Sensitivity and specificity values and overall accuracy were calculated, and receiver operating curves were generated and compared. Reliability assessment was performed using linear weighted κ statistics. RESULTS: The overall accuracies between the reference standard and different sensors and exposure times were 63.1% (CCD), 67.1% (CMOS sensor at 0.12 s) and 70.7% (CMOS sensor at 0.08 s). High specificity but low sensitivity values were found for all examination conditions at all thresholds. The area under the curve comparison values revealed no significant difference between sensor types and exposure times. Linear-weighted κ analysis revealed almost perfect agreement for all assessments. CONCLUSION: No significant difference was found for diagnostic performance of proximal caries detection between the different sensors and exposure times. The increased exposure time did not lead to a significant diagnostic benefit.

Biomimetic tooth-whitening effect of hydroxyapatite-containing mouthrinses after long-term simulated oral rinsing.

PURPOSE: To investigate the tooth-whitening effects of mouthrinses containing different sizes of hydroxyapatite (HAP) particles after prolonged application time and compare them with a commercial whitening mouthrinse. METHODS: 50 bovine incisors were stained and randomly distributed into five groups: the HAP groups with 3 µm, 200 nm and 50 nm particle size, the commercial whitening mouthrinse group and the distilled water group. The teeth underwent prolonged mouthrinse applications that were equivalent to simulated 3- and 6-month mouthrinsing. Tooth color was measured and calculated before and after mouthrinsing. The group and application time effects were analyzed with a nonparametric analysis of longitudinal data using the nparLD package in R and ANOVA-type statistic was reported. Pairwise Wilcoxon rank-sum tests with BH correction were performed to compare the tooth color changes of individual groups. The mouthrinse-treated enamel was observed by SEM. RESULTS: The whitening effect of HAP mouthrinses after the prolonged application time was confirmed. The HAP mouthrinses exhibited similar whitening effects to the commercial mouthrinses. The particle size and application time could significantly affect the whitening performance of HAP mouthrinses. The 50 nm HAP group exhibited significantly higher ΔE values than the 3 µm group after the 6-month-equivalent application (P= 0.024). A longer period of application increased significantly the ΔE and ΔL values (P< 0.05). The HAP-treated enamel surfaces were entirely covered with HAP after the 6-month-equivalent application. CLINICAL SIGNIFICANCE: The HAP nanoparticles showed better tooth-whitening performance after a longer period of mouthrinsing than the microsized HAP particles. This should be taken into consideration by dental manufacturers for optimizing the particle size for their HAP-containing products. To achieve a better outcome in tooth-whitening, the patients should apply the mouthrinse regularly for an extended period of time.

Shrinkage vectors in flowable bulk-fill and conventional composites: bulk versus incremental application.

OBJECTIVES: Sufficient depth of cure allows bulk-fill composites to be placed with a 4-mm thickness. This study investigated bulk versus incremental application methods by visualizing shrinkage vectors in flowable bulk-fill and conventional composites. MATERIALS AND METHODS: Cylindrical cavities (diameter = 6 mm, depth = 4 mm) were prepared in 24 teeth and then etched and bonded with OptiBond FL (Kerr, Italy). The composites were mixed with 2 wt% radiolucent glass beads. In one group, smart dentin replacement (SDR, Dentsply) was applied in bulk "SDR-bulk" (n = 8). In two groups, SDR and Tetric EvoFlow (Ivoclar Vivadent) were applied in two 2-mm-thick increments: "SDR-incremental" and "EvoFlow-incremental." Each material application was scanned with a micro-CT before and after light-curing (40 s, 1100 mW/cm2), and the shrinkage vectors were computed via image segmentation. Thereafter, linear polymerization shrinkage, shrinkage stress and gelation time were measured (n = 10). RESULTS: The greatest shrinkage vectors were found in "SDR-bulk" and "SDR-increment2," and the smallest were found in "SDR-increment1-covered" and "EvoFlow-increment1-covered." Shrinkage away from and toward the cavity floor was greatest in "SDR-bulk" and "EvoFlow-increment2," respectively. The mean values of the shrinkage vectors were significantly different between groups (one-way ANOVA, Tamhane's T2 test, p < 0.05). The linear polymerization shrinkage and shrinkage stress were greatest in Tetric EvoFlow, and the gelation time was greatest in "SDR-bulk." CONCLUSIONS: The bulk application method had greater values of shrinkage vectors and a higher debonding tendency at the cavity floor. CLINICAL RELEVANCE: Incremental application remains the gold standard of composite insertion.

Investigations of the optical properties of enamel and dentin for early caries detection.

INTRODUCTION: The aim of this study was to experimentally investigate the potential of different light wavelengths to distinguish between healthy and carious tissue using a two-circle goniometer. MATERIALS AND METHODS: Tooth slices were prepared from extracted human teeth that were caries free (n = 15) or had occlusal caries lesions (n = 10). The tooth slices were irradiated with diode laser modules of different wavelengths (532, 650, 780 nm). The transmitted and scattered laser light was spatially measured with a detector rotating on a two-circle goniometer. The anisotropy factor and attenuation coefficients were calculated. RESULTS: Enamel was more transparent than dentin and showed wavelength-dependent attenuation. Healthy dentin showed strong light scattering at all wavelengths, independent of the tested wavelength. The calculated attenuation coefficients of carious and healthy tooth tissue differed significantly (p < 0.05; t test). In contrast to healthy enamel, carious enamel showed lower light transmission and an increase in scattering. Differences in the light attenuation of carious versus healthy dentin were less pronounced than those for enamel. Carious dentin was slightly more transparent than healthy dentin. The light of longer wavelengths showed a better penetration of all tooth structures compared with shorter wavelengths. CONCLUSION: Healthy and carious dentin and enamel exhibited distinct optical properties using laser light at different wavelengths. In dentin, changes in the optical properties caused by caries are significantly less pronounced. CLINICAL RELEVANCE: The clear distinction between healthy and carious enamel makes optical caries diagnostic systems ideal tools for early caries detection.

Adhesion and whitening effects of P11-4 self-assembling peptide and HAP suspension on bovine enamel.

OBJECTIVES: This study evaluated the adhesion and whitening effects of a combination of P11-4 self-assembling peptide and hydroxyapatite (peptide-HAP) on bovine enamel. METHODS: Forty-six caries-free bovine teeth were selected, and 40 teeth were randomly allocated to one of five groups (n = 8). First, the effects of application frequency, exposure time, and storage in saliva on the whitening effects of an experimental low-concentrated peptide-HAP suspension (0.5 wt% HAP; Curodont, Credentis) were evaluated and compared with a commercial bleaching agent (VivaStyle Paint on Plus, VS, Ivoclar Vivadent). Tooth color was measured using a spectrophotometer (Gretag MacBeth), and color changes ΔE were statistically analyzed. Second, the effects of peptide-HAP concentration (low versus high: 6.25% HAP; Curodont Protect), and its interactions with saliva and postapplication restaining, were investigated. Third, enamel surfaces (n = 2) were treated with low concentration peptide-HAP and high-concentration peptide-HAP in polymeric and monomeric forms (Curodont Protect & Curodont Repair, Credentis) and analyzed by SEM. RESULTS: The ΔE of the low-concentration peptide-HAP suspension did not differ from that of VS. Application frequency, exposure time, and storage in saliva did not have any significant impact on whitening efficacy of the peptide-HAP suspension. Increasing the concentration of the suspension did not promote overall ΔE. SEM observations confirmed the presence of the newly generated peptide and HAP on the enamel surface. CONCLUSIONS: The peptide-HAP suspension is a mild tooth whitener, and the adhesion of peptide-HAP to enamel is concentration dependent. CLINICAL RELEVANCE: This peptide-HAP suspension is effective in offsetting discoloration caused by restaining after treatment.

A detailed report on the measures taken in the Department of Conservative Dentistry and Periodontology in Munich at the beginning of the COVID-19 outbreak.

OBJECTIVES: The corona disease (COVID-19) is developing into one of the greatest challenges for healthcare professionals around the world. In this article, we report the detailed actions taken in the Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University (LMU), Munich, Germany, during the early phase of the COVID-19 pandemic. MATERIAL AND METHODS: After a joint on-site inspection of the dental clinic with the Department of Clinical Microbiology and Hospital Hygiene, existing clinical and hygiene protocols were adapted for COVID-19 patients. RESULTS: A comprehensive summary of the preparation of the facilities as well as pre- treatment, treatment and posttreatment protocols are described and arising problems are being discussed. CONCLUSIONS: The importance of rigorous hygiene and treatment protocols as well as a sufficient supply of PPE for dental offices and hospitals is highlighted. The measures reported may be subject to change due to the dynamics of the pandemic. CLINICAL RELEVANCE: The modes of transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (e.g., droplets, aerosols, and fomites) can pose a risk for dental healthcare professionals and patients alike. The presented measures may guide dental faculties and dental practices during the early stage of the COVID-19 crisis.

Near-infrared transillumination with high dynamic range imaging for occlusal caries detection in vitro.

The aim of this study was to assess near-infrared transillumination with high dynamic range imaging (NIRT-HDRI) for occlusal caries detection in vitro and to compare it with visual inspection using the International Caries Detection and Assessment System II (ICDAS) and digital bitewing radiography (BWR). Sixty-one extracted permanent molars with sound or occlusal carious surfaces without severe cavitation were visually assembled. Two examiners assessed twice these surfaces independently using ICDAS, BWR and NIRT-HDRI. The latter was performed with a prototype consisting of two laser sources (780 nm), a CCD sensor and subsequent processing with image analysis software. Thresholds for carious surfaces, enamel and dentin lesions were defined for all methods. Micro-computed tomography served as the reference standard. Linear weighted Kappa analysis of the methods versus the reference at the threshold carious surface, enamel and dentin lesion revealed 0.59/0.08/0.12 for ICDAS, 0.37/- 0.06/0.58 for BWR and 0.33/- 0.01/0.51 for NIRT-HDRI. Sensitivity values at the three thresholds were 0.85/0.78/0.13 for ICDAS, 0.59/0.00/0.69 for BWR and 0.98/0.33/0.78 for NIRT. Specificity values at the three thresholds were 0.70/0.40/1.00 for ICDAS, 0.9./0.96/0.90 for BWR and 0.30/0.65/0.72 for NIRT-HDRI. Reliability analysis revealed substantial agreement for BWR and NIRT and almost perfect agreement for ICDAS. NIRT exhibited a strong ability to identify occlusal dental decay in general; however, it revealed a tendency towards overestimation. Its strength was the detection of dentin caries lesions compared with ICDAS and BWR. NIRT-HDRI seems to be a suitable method to detect hidden dentin caries as a supplement to visual examination.

The influence of storage temperature on fracture behavior of cryopreserved teeth-An in vitro study.

OBJECTIVES: Cryopreservation is discussed as a viable method of preserving teeth for determined autogenous tooth transplantation. Unchanged physical properties of hard tooth tissues are crucial for functional healing. Due to different thermal expansion coefficients of enamel and dentin or the crystallization process, the freezing process may lead to crack formation, which could adversely impact the long-term prognosis of the teeth. MATERIAL AND METHODS: Twenty third molars (n = 20) were frozen slowly using a conservative cryopreservation protocol and stored at -80°C (group 1) and -196°C (group 2). After a storage time of 2 weeks, the samples were thawed to a temperature of +36°C and embedded in polymethyl methacrylate blocks. Cyclic loading was carried out using a spherical steel test specimen with 50,000 mechanical load cycles, followed by load to failure testing for determination of critical load. RESULTS: No significant difference in the first load drop could be detected during the load to failure test under different storage conditions. The values until fracture correlated very closely in contralateral tooth pairs, which emphasizes the importance of crown geometry in load to failure tests. CONCLUSIONS: Conclusions: Cryopreservation, specifically the storage temperature, does not appear to have a significant effect on the physical properties of tooth transplants.