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April 2009


 Research Article

Digital image color analysis compared to direct dental CIE colorimeter

assessment under different ambient conditions


Michael  KnÖsel, dr med dent,  Rengin  Attin, dr med dent,  Klaus  Jung, dr Rer Nat,  Edgar  Brunner, prof dr Rer Nat, Dietmar Kubein-Meesenburg, prof dr med dent  &  Thomas Attin, prof dr med dent


Abstract: Purposes: To evaluate the concordance and repeatability of two in vivo methods for dental color assessment and to clarify the influence of different ambient light conditions and subject’s head position on the assessed color variables. Methods: Color assessments were performed by two examiners on 16 arbitrarily selected subjects under two different, standardized conditions of illumination and at two different standardized head angulations. CIE (L*a*b*) data for upper and lower central incisors were recorded in two different ways: (1) by an intra-oral contact dental colorimeter and (2) by processing digital images for performing color calculation using Adobe Photoshop software. The influence of the different ambient conditions on both methods, as well as the concordance of measurements was analyzed statistically using several mixed linear models. Results: Ambient light as a single factor had no significant influence on maxillary L*, a* and b* values, but it did have an effect on mandible assessments. Head angulation variation resulted in significant L* value differences using the photo method. The operator had a significant influence on values a* and b* for the photo method and on a* values for the colorimeter method. In fully lit ambient condition, the operator had a significant influence on the segregated L*, a*, and b* values. With dimmed lights, head angulation became significant, but not the operator. Evaluation of segregated L* values was error prone in both methods. Comparing both methods, DE values did not exceed 2.85 units, indicating that color differences between methods and recorded under varying ambient conditions were well below the sensitivity of the naked eye. (Am J Dent 2009;22:67-72).








Clinical significance: Both methods were appropriate for clinical color assessment and their accuracy exceeded visual control. Slight changes in ambient light did not affect upper incisor color assessment, but were more critical when lower incisors were the objective. Especially in half-lit ambient conditions, additional variations in head angulations must be avoided, to maintain measurement reliability.




*: Dr. Michael Knösel, University of Göttingen, Center of Dentistry, Department of Orthodontics, Robert-Koch-Str. 40, 37099 Göttingen, Germany. E-*:


 Research Article

Color difference of all-ceramic materials by the change of illuminants


Bin  Yu, mche  &  Yong-Keun  Lee, dds, phd


Abstract: Purpose: To determine the differences in color and color parameters (lightness, chroma and hue) of simulated layered all-ceramic specimens at a clinically relevant thickness under three CIE standard illuminants. Methods: Seven all-ceramic core materials of A2-corresponding shade, one sintering ceramic and one alloy core as references were prepared in clinically relevant thicknesses (0.4 to 0.8 mm ). A2- and A3-corresponding shades of each of the recommended veneer ceramics were fabricated so that the thickness of the layered specimens was 1.5 mm . Bovine dentin was also used as a reference. Color was measured relative to the CIE standard illuminants D65, A and F2 with a reflection spectrophotometer. Differences in color and color parameters by the change of illuminants were calculated. Repeated measures two-way ANOVA with the fixed factor of the brand of ceramics on the difference in color and color parameters by the change of illuminants (D65 to A, D65 to F2 and A to F2) was performed (α=0.05). Results: Color difference (∆E*ab) was in the range of 0.6 to 0.8 for bovine dentin, 1.3 to 3.4 for A2-veneer layered specimens and 1.6 to 4.2 for A3-veneer layered specimens. Differences in color and parameters were significantly influenced by the brand of the ceramics and the combination of illuminants (P< 0.05). (Am J Dent 2009;22:73-78).


Clinical significance: Color difference of all-ceramics by the change of illuminants was higher than that of natural dentin, and also was higher than the clinically perceptible level (∆E*ab >3.7) in several conditions. Therefore, these color discrepancies by the change of illuminants should be considered in clinical shade matching, and shade matching should be performed under the light most clinically relevant.


*: Dr. Yong-Keun Lee, Department of Dental Biomaterials Science, Dental Research Institute and BK 21 Program, School of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Korea.  E-*:



Research Article

Influence of CAM vs. CAD/CAM scanning methods and finish line of tooth preparation in the vertical misfit of zirconia bridge structures


Raquel Castillo de OyagÜe , dds, phd,  María Isabel Sánchez-Jorge, phd, AndrÉs SÁnchez Turrión, md, phd, Francesca  Monticelli , dds, msc, phd,  Manuel  Toledano, md, dds, phd  &  Raquel  Osorio , dds, phd


Abstract: Purpose: To evaluate the influence of CAD/CAM scanning method (wax-up digitization vs. direct scanning of tooth preparation) and finish line type (chamfer vs. shoulder) on the vertical fit of zirconia frameworks for three-unit posterior-lower bridges. Methods: 30 sets of two stainless steel master dies were prepared with different marginal designs (chamfer and shoulder) around the contour of each abutment. Over these samples, 30 structures for three-unit posterior-lower bridges were made with Cercon Smart Ceramics CAD/CAM system (Dentsply). An optical laser digitized the wax patterns of 15 bridge structures, and 15 pairs of master dies were directly scanned for designing by computer the remaining half of frames. All zirconia milled structures were luted onto the metallic models with a special clamp made-up to maintain constant seating pressure. Vertical discrepancy around the margins was assessed under scanning electron microscopy (SEM). Misfit data was analyzed using two-way ANOVA and Tukey’s test for multiple comparisons at α = 0.05. Results: Vertical discrepancy of the wax-up/digitized bridge structures was significantly higher than that of the computer-designed frameworks (P< 0.0001). No statistically significant differences were found between the chamfer and shoulder vertical misfit values assessed around the metallic models margins (P= 0.55). (Am J Dent 2009;22:79-83).


Clinical significance: Vertical discrepancy of zirconia structures depended on the scanning method. Precision was higher when direct scanning of prepared abutments was performed instead of wax-up digitization, even when every group of frameworks tested can be considered clinically acceptable in terms of vertical misfit. However, the finish line type (chamfer or shoulder) seemed to have no effect on the marginal adaptation of zirconia structures.


*: Prof. Raquel Osorio , Dental Materials, Dental School , University of Granada . Colegio Maximo, Campus de Cartuja s/n 18017 Granada, Spain.  E-*:


Research Article

Laboratory evaluations of a bi-level, extremely tapered bristled toothbrush

and a conventional uniform bristled toothbrush


Caren M. Barnes, rdh, ms,  David A. Covey, dds, ms,   Xiuren Shi, dds  &  Samuel L. Yankell, phd, rdh


Abstract: Purpose: To compare a uniquely shaped  tapered-bristle manual toothbrush to a toothbrush with bristles uniform in height and diameter for the ability to remove artificial plaque deposits in areas of the mouth that are difficult to access; interproximal areas, the gingival margin and subgingival. Methods: This study compared a GUM Summit+ Compact toothbrush featuring extremely tapered bristles and conventional bristle ends in a bi-level design. The upper, longest tapered bristles have the final 6 mm tapered to 0.01diameter mm at the end. The conventional rounded end bristles have less than 0.5 mm tapered down to 0.02 mm diameter. The comparison manual toothbrush (Oral-B 40 Indicator) has bristles that are uniform in height and diameter. Interproximal access efficacy was evaluated using a pressure-sensitive artificial plaque substrate placed around simulated anterior and  posterior teeth. Subgingival access and gingival margin cleaning were determined by using simulated gingiva prepared with a 0.2 mm space between the gingiva and the artificial plaque substrate on tooth surfaces and results were recorded as the artificial plaque removed below the gingiva or around the gingival margin. Results: Interproximal access values were significantly (P< 0.001) higher for the GUM Summit+ Compact than for the Oral-B 40 Indicator. The mean value for gingival margin cleaning efficacy of the GUM Summit+ Compact was significantly (P < 0.001) superior compared to the Oral-B 40 Indicator. The Gum Summit + Compact  had a significantly superior subgingival access (P< 0.001) mean value when compared to the Oral-B 40 Indicator. In this laboratory study, the GUM Summit+ Compact toothbrush was statistically significantly more effective for removing plaque from the interproximal areas, at the gingival margin and subgingivally than the Oral-B 40 Indicator toothbrush. (Am J Dent 2009;22:84-88).



Clinical significance: The GUM Summit+ Compact toothbrush was statistically significantly more effective for cleaning in interproximal areas, at the gingival margin and subgingivally than the Oral-B 40 Indicator toothbrush. It is important for dental healthcare providers to be familiar with toothbrush designs to guide toothbrush selection that best meets the patient's individual needs.




*: Dr. Caren M. Barnes, UNMC College of Dentistry, 40th & Holdrege, Lincoln, NE 68583, USA.  E-*:




 Research Article

Sealant adaptation and penetration into occlusal fissures


Barbara  Kane, bs,  Jordan  Karren, bs,  Cristina Garcia-Godoy, dds  &  Franklin Garcia-Godoy, dds, ms


Abstract: Purpose: To evaluate the adaptation and penetration into occlusal fissures of two different types of fissure sealants. Methods: Extracted third molars (n=10) with evident occlusal fissures were cleaned with a pumice/water slurry and randomly divided into two groups and sealed following the manufacturers’ directions as follows: Group 1 - Embrace fissure sealant (Pulpdent). Surfaces were cleaned and dried, then etched for 15 seconds. Excess water was removed leaving the surface slightly moist. Sealant was applied from cusp to cusp without covering marginal ridges and light cured for 20 seconds using a halogen light at 500 mW/cm2. Group 2 - ClinPro (3M Espe). Surfaces were cleaned and dried then etched for 15 seconds. The etched surface was rinsed and thoroughly dried. Dried surfaces appeared frosty white. Sealant was placed making sure not to go beyond etched area, and light cured for 20 seconds. Teeth were thermocycled (500x) and sectioned with an Isomet in a mesio-distal direction (4 slices per tooth). The sections were examined under the SEM. The marginal adaptation of the sealants was evaluated under the SEM using the following criteria: 1 = Smooth adaptation. Sealant flows with enamel. No ledges; 2 = Sealant is not well adapted. Ledge may be present. The penetration ability of the sealants was evaluated under the SEM using the following criteria: 1 = Sealant penetrated 1/3 the total length of the fissure; 2 = Sealant penetrated 1/2 the total length of the fissure; 3 = Sealant penetrated the total length of the fissure. The results were statistically analyzed using a t-test. Results: Embrace showed consistently more intimate marginal adaptation than ClinPro in fissures of the same approximate width and depth (P< 0.05). (Am J Dent 2009;22:89-91).


Clinical significance: Embrace showed consistently more intimate marginal adaptation than ClinPro in fissures of the same approximate width and depth. The superior adaptation and penetration of Embrace may produce longer lasting sealants.


*: Dr. Franklin Garcia-Godoy, College of Dental Medicine, Nova Southeastern University, 3200 South University Drive, Fort Lauderdale, Florida  33328, USA. E-*:





Research Article

Effect of heat on the flow of commercial composites


Juliana da Costa, dds, ms,  Rose  McPharlin, dmd,  Thomas  Hilton, dmd, ms  &  Jack  Ferracane, phd


Abstract: Purpose: This study compared the flowability of various commercial dental composites to flowable composites in response to warming in a composite warmer. Methods: 18 conventional resin composites and four flowable composites were tested at room temperature (23°C), and the conventional composites were tested after pre-heating in a Calset unit (Addent) to 54°C or 68°C. Flowability was determined by placing uncured composite onto plastic sheets and loading for 180 seconds (4 kg load) while maintained at 36°C (conditioning temperature [n=3]) to simulate placing room temperature composite into a tooth. The composite was light-cured for 40 seconds. The thickness of the specimens were measured. Thickness/volume (T/V) were compared for the composites for the three temperatures, and between flowable and conventional composites at 23°C (one-way ANOVA/Tukey's; P< 0.05). Results: At 23°C, the flowable composites T/V were significantly less than the conventional composites (P< 0.001), ranging from 0.46 mm/cm3 (Perma Flo HV) to 1.43 mm/cm3 (Point 4 Flow), except for Z100 (1.48 mm/cm3/±0.32), Z250 (1.79 mm/cm3/±0.09), Gradia (1.53 mm/cm3/±0.07), and Grandio (1.98 mm/cm3/±0.07). The T/V of the conventional composites were not significantly different at all three temperatures (P> 0.05), except for Esthet-X which showed the greatest T/V decrease at 68°C (3.84 mm/cm3/±0.3) compared to 23°C (6.44 mm/cm3/±0.36) and 4 Seasons which showed the greatest T/V decrease at 54°C (3 mm/cm3/±0.1) compared to 23°C (3.57 mm/cm3/±0.1.4). (Am J Dent 2009;22:92-96).




Clinical significance: Warming of certain composites might increase their flowability, which may improve the composite adaptation to a cavity preparation.



*: Dr. Juliana da Costa, Department of Restorative Dentistry, Division of Operative Dentistry, OHSU School of Dentistry, 611 S.W. Campus Drive, Portland, OR  97369, USA.  E-*





Research Article

Light polymerization-dependent changes in color and translucency

of resin composites


MarÍa  del Mar  PÉrez, phd,  Arafa Saleh, phd,  Rosa  Pulgar, md, dds, phd  &  Rade  D.  Paravina, dds , ms , phd


Abstract: Purpose: To determine the influence of type of polymerization light on changes in color and translucency of resin composites. Methods: 16 shades of commercial composites were analyzed. Specimens were polymerized with quartz-tungsten-halogen (QTH) and light-emitting diode (LED) polymerization light. Color of non-polymerized and polymerized composites was measured against white and black backgrounds using a spectroradiometer. Changes in color (DE’), translucency (DTP’) and color parameters (DL’, DC’ and Dh’) were calculated for each polymerization light. The differences among DE’ values and among DTP’ values obtained for each device were analyzed by two-way ANOVA. Multiple regression analysis was used to determine the influence of color parameters on DE’ and DTP’. Results: The results indicated that there was significant difference among the DE’ and DTP’ values obtained using QTH and LED light polymerization (P< 0.05). The prediction equations for DE’ and DTP’ based on the multiple regression analyses indicated that DE’ was mainly caused by DC’ for both lights. However DTP’ was mainly caused by Dh’ for LED light and by the DC’ for QTH light. Changes in translucency significantly influenced the overall color changes after polymerization. (Am J Dent 2009;22:97-101).


Clinical significance: The type of polymerization light (LED or QTH) influences polymerization-dependent changes in color and translucency of resin composites. Therefore, dental professionals should be aware that the final color and translucency of composite restoration may vary based on the type of light polymerization used.


*: Dr. María del Mar Pérez, Department of Optics, Faculty of Sciences, University of Granada , 18071 Granada , Spain . E-*:



Research Article

Subjective and objective perceptions of specular gloss and surface

roughness of esthetic resin composites before and after artificial aging


Nadine  Barucci-Pfister, med dent  &  Till  N.  GÖhring, pd, dr med dent


Abstract: Purpose: To correlate measurements of specular gloss and surface roughness of resin composite materials with subjective perception of luster before and after artificial aging. Methods: Polished specimens of eight composites were compared with human enamel (HE): microfilled SR Adoro (SR); microhybrid Artemis (AR), Enamel HFO (EHFO), Miris (MI), Tetric Ceram (TC), Venus (VE); and nanohybrid CeramX (CX) and nanofilled Filtek Supreme (FS). Before, during and after artificial aging (6000 thermal changes between 5°C and 50°C in an artificial oral environment, 240 hours storage in a container with ethanol, 300 minutes of toothbrushing), specular gloss and surface roughness were measured. Initial and endpoint gloss results were correlated with subjective luster rankings of 10 individuals. Results: Artificial aging resulted in minor (EHFO, CX, FS), moderate (SR, MI, TC, VE) to high (AR) increases in surface roughness. Specular gloss decreased linearly for SR and FS, but decreased after an initial increase for all other materials. Subjectively, AR and FS were rated more and TC, VE and CX less lustrous than HE at baseline. After aging, luster of EHFO and FS was ranked higher and AR, TC, and VE lower than HE. Surface roughness was consistent with subjective perceptions (correlation coefficient: initial r = 0.913; endpoint r= 0.944, P≤ 0.0006), whereas specular gloss was consistent with subjective perceptions only after artificial aging (initial r= 0.616, P= 0.1084; endpoint r= 0.834, P = 0.0072). (Am J Dent 2009; 22:102-110).


Clinical significance: Whereas surface roughness increased during artificial aging, specular gloss showed an initial increase for most materials before subsequent decrease. Only a poor correlation was found between these objective measurements. However they corresponded well with subjective perception after artificial aging when differences in luster became more obvious.


*: Priv.-Doz. Dr. Till N. Göhring, Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University of Zurich, Plattenstrasse 11, CH-8028 Zurich, Switzerland.  E-*:





Research Article

Evaluation of different flowable materials for bonding brackets


AscensiÓn  Vicente, dds, phd  &  Luis  A.  Bravo, md, dds, ms, phd


Abstract: Purpose: To compare the shear bond strength and the adhesive remnant on the tooth after debonding of brackets bonded with a traditional orthodontic resin (Transbond XT), a flowable composite (X-Flow), a flowable compomer (Dyract Flow) and a flowable giomer (Beautifil Flow). Methods: 105 extracted human premolars were used. They were divided into four groups: (1) Transbond XT, (2) X-Flow, (3) Dyract Flow, and (4) Beautifil Flow. Shear bond strength was measured using a universal testing machine with a cross-head speed of 1 mm/minute. The adhesive remnant on the tooth after debonding was quantified using image analysis. Results: No significant differences were found between the shear bond strengths of the different groups evaluated (P> 0.05). Transbond XT left significantly more adhesive on the tooth than the three flowable materials, and among the flowable materials, X-Flow left significantly less adhesive than Beautifil Flow (P< 0.008). (Am J Dent 2009;22:111-114).


Clinical significance: The flowable composite, flowable compomer and flowable giomer evaluated in this study all achieved bond strengths similar to that of traditional bond systems for brackets and left significantly less adhesive remnant on teeth after debonding. They may therefore be considered suitable materials for bracket bonding although in vivo studies are necessary in order to confirm this. Furthermore, their flowable characteristics did not affect the adequate positioning of brackets.


*: Dr. Ascensión Vicente, Orthodontic Teaching Unit, Dental Clinic, The University of Murcia, Hospital Morales Meseguer, 2nd Floor, C/. Marqués de los Vélez, s/n, 30008 Murcia, Spain. E-*:




Research Article

The in vitro effect of a collagenolytic enzyme inhibitor on lesion development in root dentin


Yasushi  Fukuda, phd,  Syozi  Nakashima, Phd  &  Takashi  Ujiie, msc


Abstract: Purpose: To evaluate the effects of a new active collagenase inhibitor, Pirocton Olamine (PO), on acid demineralization in dentin and to investigate possible mechanisms of the inhibitory effects. Methods: Demineralized bovine dentin sections were cyclically exposed to one of the test solutions containing PO (0 - 0.33%) and NaF (0.07%) for 3 minutes, then to a Clostridium histolyticum (Ch-collagenase) collagenase solution for 16 hours and finally to an acetate buffer solution for 6 hours for further demineralization within a single day. This cyclic treatment was repeated three times for 3 days. Changes in the mineral loss and lesion depth were quantified by transverse microradiography, and the extent of the degradation by the collagenase in the collagen matrix was measured by microscopic observation after the completion of the 3-day cyclic treatments. Possible mechanisms of PO inhibitory effects on collagen matrix degradation were tested by incubating PO with one of the substances (Ch-collagenase, bovine tendon collagen pieces, zinc2+ (acetate) which is essential ion for collagenolytic activity) at 37°C. Following 1 hour incubation, the incubated solutions were filtrated and PO concentrations (unbound to the substances) in the filtrates were spectroscopically measured. Results: With increasing PO concentrations, the inhibition rates of collagen matrix degradation and the mineral loss were increased. Moreover, there was a positive statistical correlation between mineral loss and collagen matrix degradation, demonstrating that preservation of the collagen matrix would contribute to inhibiting acid demineralization. While the spectroscopic measurements indicated that PO possessed binding to these substances, PO exerted its inhibitory action primarily on the collagenolytic activity. (Am J Dent 2009;22:115-121).


Clinical significance: Inhibition of collagen matrix degradation could contribute to inhibiting acid demineralization of dentin by preserving the dentin matrix and possibly enhancing fluoride retention in the collagen matrix of demineralized dentin. The combined use of PO and fluoride could be a useful tool in root caries prevention.



*: Dr. Yasushi Fukuda, Oral-Care Research Laboratories, Lion Corporation, 100 Tajima, Odawara-shi, Kanagawa 256-0811,   Japan .  E-*:


Research Article

Influence of different luting concepts on long term retentive strength

of zirconia crowns


Claus-Peter Ernst, prof dr,  Erwin Aksoy, dr, Elmar Stender, dr   &  Brita Willershausen, prof dr


Abstract: Purpose: To evaluate the retentive strength of a resin cement in combination with a conventional adhesive (Variolink II/Syntac Classic), two resin cements with self-etching adhesives (Panavia F 2.0/ED Primer, Multilink/Multilink Primer A/B), two self-adhering cements (RelyX Unicem Aplicap, Maxcem), and a resin-modified glass-ionomer cement (FujiCem) after cementation of zirconium-oxide ceramic crowns (LAVA) on extracted human teeth. Methods: 160 extracted teeth (n=20) were prepared in a standardized manner (10°, h= 3 mm). The crowns’ inner surfaces were air-abraded/sandblasted (Rocatec Pre). Additional pretreatment was carried out with Multilink (metal primer or Monobond S). With RelyX Unicem Aplicap, an additional group that also received Rocatec Plus pretreatment was examined. Immediately after thermocycling (x5000, 5/55°C), 50% of the luted ceramic crowns (n = 10) were pulled off along the path of insertion (Zwick 1425); the remaining samples (n = 10) were tested after 1 year of water storage. Statistical analysis was performed using the Wilcoxon Mann-Whitney U-test and Bonferroni adjustment at the 5% level of significance. Results: The retentive strength values (N/mm2) after 1 year of water storage were (Min/Q1/Median/Q3/Max): Variolink II/Syntac: 1.0/1.9/2.5/3.3/5.2, Panavia F 2.0: 1.5/1.8/2.1/3.6/5,4, Multilink/Metallprimer: 2.9/4.6/5.3/9.4/11,7, Multilink/Monobond S: 4.1/4.8/5.4/7.7/12.6, RelyX Unicem Aplicap: 3.9/6.3/7.5/9.0/10.7, RelyX Unicem Aplicap/Rocatec Plus: 4.4/5.8/7.2/9.4/11.9, Maxcem: 0.9/2.2/3.0/3.3/4.5, FujiCem: 1.6/2.7/4.3/5.4/6.7. RelyX Unicem Aplicap and Multilink showed the highest median retentive strength values. Long-term water storage did not affect the retentive strength. (Am J Dent 2009;22:122-128).


Clinical significance: Some simplified “self adhering cements” are certainly able to provide retentive strengths between zirconia crowns and dentin stumps that are comparable to those mediated by classical adhesive luting materials.






*: Prof. Dr. Claus-Peter Ernst, Department of Operative Dentistry, Augustusplatz 2, 55131 Mainz , Germany .  E-*:








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