Translucency and flexural strength of translucent zirconia ceramics.

STATEMENT OF PROBLEM: Translucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are sparse. PURPOSE: The purpose of this in vitro study was to compare the relationship between translucency and biaxial flexural strength of recently developed high-translucency zirconia, high-strength zirconia, and lithium disilicate ceramics. MATERIAL AND METHODS: Disks (n=12) were fabricated for 5 ceramic materials: high-strength zirconia (BruxZir 16 shaded), translucent zirconia (BruxZir Anterior shaded, Katana UTML, Katana STML), and lithium disilicate (IPS e.max, Press HT, and LT). A standard tessellation language (STL) file was designed, and the specimen milled, finished, and glazed according to manufacturer's instructions for each material. The translucency parameter was calculated against black and white backgrounds and white and stump shade with ND4 background by using a spectrophotometer. Biaxial flexural strength was calculated by using the 3-ball test. The load was applied at a crosshead speed of 0.5 mm/min with a 49-N load cell until failure occurred. Translucency parameter and biaxial flexural strength data were analyzed with 1-way analysis of variance (ANOVA). A Tukey honest significant difference multiple comparison test was used to determine significant differences (α=.05). RESULTS: The IPS e.max HT was more translucent against both backgrounds (32.85 for black/white and 15.34 for white/stump), while BruxZir 16 was the least translucent (19.78 for B/W and 8.83 for W/S). All groups tested differed in translucency (P<.001) except for BruxZir Anterior and Katana STML, which were not significantly different (P=.052). For biaxial flexural strength, BruxZir 16 had the highest strength (995.44 MPa) and e.max HT, the lowest (186.75 MPa). No significant differences were found between BruxZir anterior and Katana STML, Katana UTML and IPS e.max LT, or IPS e.max LT and IPS e.max HT (P>.05). Translucency parameter values using both backgrounds were strongly correlated (r=0.99). However, biaxial flexural strength values were inversely related to translucency parameter values when using black/white and white/stump shade but with high correlation (r=-0.777 and -0.756 respectively). CONCLUSIONS: Lithium disilicate was the most translucent and yet the weakest material, whereas high-strength zirconia was the most opaque ceramic and the strongest. Katana UTML had the highest translucency but was weakest among translucent and high-strength zirconia materials. Overall, translucency was negatively correlated with biaxial flexural strength.

Retrospective evaluation of the clinical performance and longevity of porcelain laminate veneers 7 to 14 years after cementation.

STATEMENT OF PROBLEM: Studies on the long-term clinical assessment and longevity of porcelain laminate veneers (PLVs) are lacking. PURPOSE: The purpose of this clinical study was to assess the clinical performance and longevity of PLVs after 7 to 14 years of clinical service. MATERIAL AND METHODS: Patients with PLVs placed 7 to 14 years earlier were recalled for clinical evaluation. At the recall visit, clinical parameters such as margin integrity, margin discoloration, porcelain surface, anatomic form, and secondary caries were evaluated according to the Ryge criteria. Standardized photographs of veneers were made for each participant. Data were tabulated for all descriptive criteria and analyzed statistically. The Cohen Kappa assessment was carried out to determine interrater agreement, the Kaplan-Meier survival analysis for survival probability, and the Cox regression for significance between the arches. RESULTS: One hundred and fourteen veneers (83 maxillary and 31 mandibular) were evaluated in 26 participants, including 19 women restored with 87 veneers and 7 men restored with 27 veneers. Distribution of the veneers included 37 central incisors, 41 laterals, and 36 canines. The Alfa ratings for the veneers were as follows: porcelain surface (85%), anatomic form (87%), and secondary caries (96%). For margin integrity, 37% rated Alfa, 60% Bravo, and 3% Charlie. For margin discoloration, 56% rated Alfa and 44% Bravo. The overall Cohen Kappa interrater agreement was 0.7023 with an agreement rate of 88.3%. Clinical deficiencies included fracture rate of 4.35% (n=5); porcelain chipping 5.26% (n=6); caries 4% (n=4); debonding 2% (n=2); crack/craze lines 5.26% (n=6); loss of vitality 2% (n=2); and replaced veneers 4.38% (n=5). The main reason for failure was porcelain fracture. The survival rate for the veneers was 98%. The Kaplan-Meier success probability was 0.976 at 7 years and 0.882 at 14 years. CONCLUSIONS: Within the limitations of this clinical study, PLVs exhibited an estimated survival probability of 0.976 over 7 years and 0.882 over 14 years, a high survival rate of 98%, and a low failure rate of 4.38%.

The effect of antacid on salivary pH in patients with and without dental erosion after multiple acid challenges.

PURPOSE: To evaluate the effect of antacid swish in the salivary pH values and to monitor the pH changes in subjects with and without dental erosion after multiple acid challenge tests. METHODS: 20 subjects with tooth erosion were matched in age and gender with 20 healthy controls according to specific inclusion/exclusion criteria. Baseline measures were taken of salivary pH, buffering capacity and salivary flow rate using the Saliva Check System. Subjects swished with Diet Pepsi three times at 10-minute intervals. Changes in pH were monitored using a digital pH meter at 0-, 5-, and 10- minute intervals and at every 5 minutes after the third swish until pH resumed baseline value or 45 minutes relapse. Swishing regimen was repeated on a second visit, followed by swishing with sugar-free liquid antacid (Mylanta Supreme). Recovery times were also recorded. Data was analyzed using independent t-tests, repeated measures ANOVA, and Fisher's exact test (α= 0.05). RESULTS: Baseline buffering capacity and flow rate were not significantly different between groups (P= 0.542; P= 0.2831, respectively). Baseline salivary pH values were similar between groups (P= 0.721). No significant differences in salivary pH values were found between erosion and non-erosion groups in response to multiple acid challenges (P= 0.695) or antacid neutralization (P= 0.861). Analysis of salivary pH recovery time revealed no significant differences between groups after acid challenges (P= 0.091) or after the use of antacid (P= 0.118). There was a highly significant difference in the survival curves of the two groups on Day 2, with the non-erosion group resolving significantly faster than the erosion group (P= 0.0086).

Influence of post material and length on endodontically treated incisors: an in vitro and finite element study.

STATEMENT OF PROBLEM: Cast posts require sufficient length for prosthesis retention and root strength. For prefabricated metal and fiber posts, the effects of different post lengths on the strength and internal stress of the surrounding root need evaluation. PURPOSE: The purpose of this study was to examine, using both experimental and finite element (FE) approaches, the influence of post material and length on the mechanical response of endodontically treated teeth. MATERIAL AND METHODS: Sixty extracted incisors were endodontically treated and then restored with 1 of 3 prefabricated posts: stainless steel (SS), carbon fiber (CF), and glass fiber (GF), with intraradicular lengths of either 5 or 10 mm (n=10). After composite resin core and crown restorations, these teeth were thermal cycled and then loaded to fracture in an oblique direction. Statistical analysis was performed for the effects of post material and length on failure loads using 2-way ANOVA (α=.05). In addition, corresponding FE models of an incisor restored with a post were developed to examine mechanical responses. The simulated tooth was loaded with a 100-N oblique force to analyze the stress in the root dentin. RESULTS: The SS/5 mm and all fiber post groups presented no statistical differences, with mean (SD) fracture loads of 1247 to 1339 (53 to 121) N. The SS/10 mm group exhibited a lower fracture load, 973 (115) N, and a higher incidence of unfavorable root fracture (P<.05). The FE analysis showed high stress around the apical end of the long SS post, while stress was concentrated around the crown margins in the fiber post groups. CONCLUSIONS: Both long and short fiber posts provided root fracture resistance comparable to that of SS posts. For metal posts, extending the post length does not effectively prevent root fracture in restored teeth.

In vivo evaluation of DIAGNOdent for the quantification of occlusal dental caries.

The accurate diagnosis of non-cavitated occlusal caries is generally considered problematic. Induced fluorescence quantified by the DIAGNOdent device (KaVo) gives a reading from 0-99, which may help in the caries diagnostic process. There is some controversy around the implication of increased severity of decay with increased DIAGNOdent readings. This in vivo study assessed the correlation of depth and volume of decay as it was removed by traditional rotary handpieces with DIAGNOdent readings and determined sensitivities/specificities of the device at different cut-off points. Included in the current study were 31 patients providing 60 permanent molar and premolar occlusal surfaces suspected of dentinal decay. DIAGNOdent readings were recorded, along with lesion depth (as measured by periodontal probe) and volume measurements (as calculated from measuring the mass of a polyvinyl siloxane impression of the cavity, divided by the material's calculated density). Clinical detection of decay at the DEJ was used as the gold-standard to calculate an appropriate cut-off. Pearson correlation coefficients indicated that DIAGNOdent readings were weakly correlated with lesion depth (r = 0.47) and lesion volume (also r = 0.47). An appropriate cut-off point for the sample in the current study was calculated between 35 and 40; a more specific cut-off point could not be determined due to the sample size distribution. It was concluded that the DIAGNOdent device should be used as an adjunct in the caries diagnosis and treatment planning process.

Estimation of clinical axial extension of Class II caries lesions with ultraspeed and digital radiographs: an in-vivo study.

This study compared the newly introduced direct digital radiographic (DDR) system (RVG-6000) with conventional bitewing radiographs (D-speed film) to estimate the extension of Class II caries lesions. The patient's discomfort related to placement of each radiographic packet was also evaluated. Fifty-one Class II caries lesions were selected. Affected teeth were radiographed with D-speed film and t he RVG-6000 size 2sensor. Patients were asked to complete a one-page questionnaire regarding discomfort during the radiographic examination. The true caries depth was validated clinically from intra-operative photographs that captured the cross-sectional views of the lesion at its deepest point. During the operative procedures, the cavitation status was also recorded. A reference device was placed on the occlusal surface of the treatment or the adjacent tooth before taking radiographs and during the operative procedure. The caries lesion extension from the dentino-enamel junction (DEJ) was measured in mm on eachradiograph and the results were compared to the true clinical depth. Both radiographs significantly underestimated the clinical depth (p < 0.0001), but the RVG-6000 images were significantly closer to the actual depth of the lesion than the D-speed film (p = 0.0031). All of the lesions which were diagnosed radiographically to be deeper than 1 mm into dentin were cavitated. Size, sharp edges of the sensor or both comprised the source(s) of most of the discomfort caused by D-speed film (64%) and RVG-6000 sensor (79%). The results of this study showed that both types of radiographic images tend to underestimate caries depth; however, the RVG-6000 image was more accurate than the D-speed film. This study also provides information about sources of the patient's discomfort associated with these radiographs.

Adhesive resin and the hydrophilic monomer HEMA induce VEGF expression on dental pulp cells and macrophages.

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis by inducing endothelial cell proliferation, migration and survival. Direct pulp capping with an adhesive resin system was shown to induce local increase in blood vessel density and lack of dentin bridging. However, the mechanisms involved in the increase in blood vessel density observed near the pulp exposures capped with an adhesive resin are largely unknown. OBJECTIVES.: To investigate the effect of an adhesive resin or one of its hydrophilic monomers (HEMA), in the expression of VEGF by pulp cells. METHODS.: Mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), gingival fibroblasts, and macrophages were exposed to SingleBond (3M) or to 0-1000nM HEMA. VEGF expression was evaluated by ELISA and semi-quantitative RT-PCR. RESULTS AND SIGNIFICANCE.: VEGF expression was upregulated in MDPC-23 cells exposed to HEMA (p<0.001) or to SingleBond (p<0.018), and in macrophages exposed to HEMA (p<0.001) or SingleBond (p=0.001). In contrast, VEGF expression remained unchanged in undifferentiated pulp cells (OD-21), or fibroblasts exposed to either HEMA or Single Bond (p>0.05). Treatment with SingleBond or HEMA did not affect VEGF expression at the mRNA level of any cell type evaluated here, suggesting that the induction of VEGF expression in these cells is regulated primarily at the post-transcriptional level. These findings suggest that VEGF is involved in the regulation of pulp neovascularization observed in response to the application of adhesive resins at site of pulp exposure.

Comparison of the efficiency and effectiveness of various techniques for removal of fiber posts.

A study was conducted to determine the efficiency and effectiveness of several techniques for fiber post removal. Four groups of 20 mandibular premolars were endodontically treated and obturated. Post spaces were prepared for the following post systems: ParaPost XH, ParaPost Fiber White, Luscent Anchors, and Aestheti-Plus. After cementation, 10 posts of each group were removed with their corresponding manufacturer's removal kit and the other 10 removed with diamond burs and ultrasonics. Removal times were recorded and the teeth were sectioned vertically and microscopically analyzed for removal effectiveness based on a 0 to 5 point scale. Removal kits removed Luscent Anchors the fastest (mean = 3.9 min) and most effectively (mean = 2.6), while Aestheti-Plus posts were removed the slowest (mean = 7.3 min) and least effectively (mean = 3.4). Diamonds and ultrasonics required an average of 10 additional minutes for each fiber post system removal, yet removal effectiveness improved half a point. The results suggest recommended removal kits were significantly more efficient, while diamonds and ultrasonics were more effective. Removal kits could be enhanced with subsequent ultrasonic instrumentation to remove remaining fibers and cement.

The clinical performance of CAD/CAM-generated composite inlays.

BACKGROUND: The authors conducted a study to evaluate the longitudinal clinical performance of a resin-based composite (Paradigm, 3M ESPE, St. Paul, Minn.) for computer-aided design/computer-aided manufacturing (CAD/CAM)-generated adhesive inlays. METHODS: The researchers used a CAD/CAM unit (CEREC 2, Sirona Dental Systems, Bensheim Germany) to fabricate 40 porcelain (Vita Mark II, Vita Zahnfabrik, Bad Säckingen, Germany) and 40 resin-based composite (Paradigm, 3M ESPE) inlays. Both restorative materials were cemented with a total-etch technique using Single Bond dental adhesive (3M ESPE) and a dual-cured resin cement (RelyX ARC Adhesive Resin Cement, 3M ESPE). Two examiners evaluated the inlays using modified U.S. Public Health Service (PHS) criteria at six months, one year, two years and three years. RESULTS: No sensitivity was reported for either material at any recall period. There was no significant difference between the two materials relative to margin adaptation at three years. Margin adaptation initially was very good for both materials, with an increase in margin detection due to apparent wear of the resin-based composite luting agent. There was a significant difference in color match between the two materials at three years, with 91.4 percent of the resin-based composite inlays and 58.8 percent of the porcelain inlays rated Alfa. CONCLUSIONS AND CLINICAL IMPLICATIONS: The resin-based composite inlays had a significantly better color match at three years than did the porcelain inlays. Resin-based composite CAD/CAM inlays performed as well as porcelain CAD/CAM inlays after three years of clinical service.

Radiographic versus clinical extension of Class II carious lesions using an F-speed film.

This study investigated the difference in the apparent radiographic and true clinical extension of Class II carious lesions. Sixty-two lesions in both maxillary and mandibular premolars and molars were radiographed using Insight bitewing film. Class II lesions were scored independently by two masked examiners using an 8-point lesion severity scale. During the restoration process the lesions were dissected in a stepwise fashion from the occlusal aspect. Intraoperative photographs (2x) of the lesions were made, utilizing a novel measurement device in the field as a point of reference. Subsequently, the lesions were all given clinical scores using the same 8-point scale. Statistical analysis showed a significant difference between the true clinical extension of the lesions compared to the radiographic score. "Aggressive" and "Conservative" radiographic diagnoses underestimated the true clinical extent by 0.66 mm and 0.91 mm, respectively. No statistical difference was found between premolars and molars or maxillary and mandibular arches. The results of this study help to define the parameters for making restorative treatment decisions involving Class II carious lesions.

Treatment decisions and conservation of tooth structure.

New technology is becoming available to help establish an early diagnosis of incipient and hidden pit and fissure caries, and microdentistry techniques are being developed to follow the principles of minimal intervention. Following the accurate diagnosis of suspected lesions, early intervention can be in the form of chemotherapeutics to promote remineralization or conservative intervention to minimize tooth structure loss. Patient risk factors should have a role in developing and individualized treatment program. The life cycle of a restored molar is used in this article to illustrate the long-term value of early diagnosis, preventive therapy, and conservative intervention to preserve tooth structure and to extend the retention of healthy teeth.

Polymerization shrinkage and depth of cure of packable composites.

OBJECTIVE: This investigation evaluated polymerization shrinkage and depth of cure of five packable composites. METHOD AND MATERIALS: Five materials were used for the investigation: Alert, Surefil, Solitaire, P60, and Prodigy Condensable. Groups of 10 specimens of each material were made measuring either 2 or 5 mm in thickness, mounted in a testing jig, and polymerized using a dental curing light. Linear shrinkage was recorded and converted to a volumetric value. To evaluate depth of cure, ten specimens of each material were fabricated in both 2- and 5-mm thicknesses, and a Knoop hardness number was recorded on the top and bottom surfaces 5 minutes after light curing. A one-way analysis of variance statistical test was used to determine if there was a significant difference among materials. A Tukey multiple comparison test was then used to determine where significant differences existed. RESULTS: The volumetric shrinkage for the 2-mm-thick specimens from highest shrinkage to lowest were: Solitaire (3.3%), Prodigy Condensable (1.8%), Surefil (1.4%), P60 (1.2%), and Alert (0.2%). The 5-mm-thick specimens were ranked as follows: Solitaire (2.1%), Prodigy Condensable (1.0%), P60 (0.9%), Surefil (0.8%), and Alert (0.3%). Hardness for the bottom surface of the 2-mm-thick specimens showed that P60 (48.5) and Alert (42.6) had the highest values. Solitaire (11.2) had a significantly lower value. Hardness for the bottom surface at 5-mm thickness showed Alert (16.5) and P60 (16.3) with higher values than Surefil (8.9). CONCLUSION: Solitaire had the most shrinkage and Alert the least at both 2- and 5-mm depths. Depth of cure was severely compromised for all materials at 5 mm.

Early treatment of incipient carious lesions: a two-year clinical evaluation.

BACKGROUND: The purpose of this study was to quantify conservation of tooth structure and evaluate the efficacy of early treatment of questionable carious lesions in pits and fissures of posterior teeth using air abrasion followed by placement of preventive resin restorations. METHODS: Ninety-three patients with 223 questionably carious teeth, mainly with darkly stained pits and fissures, were recruited from general dentistry clinics. After baseline evaluation, each tooth was randomly assigned to either an early treatment or control group. The authors used air abrasion to investigate the pits and fissures of teeth in the early treatment group. The teeth were sealed and restored with a flowable resin-based composite. All teeth in both groups were examined at six-month intervals to clinically evaluate the quality of the restorations and the caries status of the control teeth. RESULTS: After two years, two of the 113 restorations in the early treatment group required further treatment because of penetrating stain at a margin. In the control group, 14 teeth required treatment because of caries. The mean weight of the impression material--a surrogate measure of volume of removed tooth structure--in preparations that extended into dentin in the early treatment group was 0.0260 grams compared with 0.0281 g in the control group. There was no statistically significant difference between the impression weights (P = .390). CONCLUSION: After two years of a proposed five-year study, the authors concluded that conservation of tooth structure was not substantiated by early treatment. CLINICAL IMPLICATIONS: Treating questionable carious lesions early may not conserve tooth structure.

A clinical evaluation of chairside lithium disilicate CAD/CAM crowns: a two-year report.

BACKGROUND: Developments in ceramic material science have led to improvements in the physical properties of modern ceramics, leading to a substantial increase in the clinical use of all-ceramic restorations. The authors evaluated the clinical performance of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent, Amherst, N.Y.) all-ceramic crowns. METHODS: The authors fabricated 62 lithium disilicate crowns with a chairside computer-aided design/computer-aided manufacturing (CAD/CAM) system (CEREC 3, Sirona Dental Systems, Charlotte, N.C.) and cemented them with two types of adhesive resin cements. Two examiners used modified U.S. Public Health Service criteria to evaluate the crowns at baseline, six months, one year and two years. RESULTS: There were no clinically identified cases of crown fracture or surface chipping. There was no reported sensitivity at one or two years with either cement. For margin discoloration, the percentage Alfa score was 86.9 percent for crowns cemented with a self-etching, dual-curing cement. All other percentage Alfa scores were greater than 92.0 percent, indicating no appreciable change in the crowns during the two-year study. CONCLUSIONS: The results show that lithium disilicate crowns performed well after two years of clinical service. CLINICAL IMPLICATIONS: Early results indicate that monolithic lithium disilicate CAD/CAM crowns may be an effective option for all-ceramic crowns.

Marginal adaptation and color stability of four provisional materials.

PURPOSE: A number of provisional restorative materials exist on the market. This study tested marginal fit and color stability of three provisional restorative materials and a control. MATERIALS AND METHODS: Two auto-cure materials, Protemp Garant and Integrity, and one dual-cure material, Luxatemp Solar, were tested against SNAP, a polyethyl methacrylate control. A maxillary right central incisor ivorine tooth was prepared for a full coverage all-ceramic crown, with a 1.5-mm chamfer margin. Four points were engraved at a point 1 mm below the facial, lingual, mesial, and distal margins, and replicas (n = 40) were produced by the manufacturer. Provisional crowns (n = 10 x 4) were fabricated on the individual replicas using a polyethylene coping template. The crowns were trimmed under magnification using an acrylic bur. The distance from the crown margins to a point tangent to the engraved markings was measured under 10x magnification and recorded. For color stability, 10-mm diameter x 2-mm thick discs (n = 10 x 4) were fabricated and immersed cyclically in tea for 1 week in a Tucillo/Nielson apparatus. Color measurements were recorded for each specimen at baseline and after staining. DeltaE values were calculated to determine the extent of the color change. RESULTS: The means of the four marginal discrepancy measurements for each specimen were analyzed using a 1-way ANOVA and Tukey post-hoc comparison. Luxatemp Solar had statistically significant marginal discrepancy (319 microm, p < 0.05) when compared to the other provisional materials. A significant color change (DeltaE = 4.33, p < 0.05) was found for Protemp Garant. CONCLUSION: The dual-cure temporary material (Luxatemp Solar) exhibited significantly more discrepancy at the margin than the auto-cure bis-acryl materials or acrylic control. Protemp Garant exhibited a clinically noticeable change in shade after 1 week in staining solution, whereas the other materials did not exhibit a clinically noticeable change. CLINICAL IMPLICATIONS: Provisional crowns fabricated from SNAP, Protemp Garant, and Integrity exhibited similarly low marginal discrepancy. SNAP, Luxatemp Solar, and Integrity did not demonstrate a clinically detectable change in shade after 1 week in a staining solution.

Shear strength of core-veneer interface in bi-layered ceramics.

STATEMENT OF PROBLEM: Delamination of veneering porcelain from underlying ceramic substrates has been reported for all-ceramic restorations. Whether this phenomenon is an inherent weakness of the veneering porcelain due to a weak interface between the veneering and the core porcelains, or merely a fracture through the veneering porcelain itself, has not been explored. PURPOSE: The purpose of this study was to investigate the strength of the substructure and veneering porcelain interface in all-ceramic systems. METHODS: The all-ceramic systems tested with their respective veneering porcelains were IPS-Empress2 with Eris (IE), Procera AllCeram with AllCeram (PA), Procera AllZircon with CZR (PZ), and DC-Zircon with Vita D (DC). The veneering porcelain recommended by the manufacturer for each material was fired to the ceramic core. A metal ceramic (MC) combination was tested as a control group. Sixty specimens, 12 for each system and control, were made from 1 master die. A cylinder of veneering porcelain 2.4 mm in diameter was applied using a specially designed aluminum split mold. After firing, the specimens were placed in a mounting jig and subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.50 mm/min until failure. Average shear strengths (MPa) were analyzed with a 1-way analysis of variance and the Tukey test (alpha=.05). The failed specimens were examined microscopically at original magnification x20 to classify the mode of failure as cohesive in the core, cohesive in the veneer, or adhesive at the interface. RESULTS: The mean shear strengths (+/-SD) in MPa were MC control 30.16 +/- 5.88; IE bonded to Eris 30.86 +/- 6.47; PZ bonded to CZR 28.03 +/- 5.03; DC bonded to Vita D 27.90 +/- 4.79; and PA bonded to AllCeram 22.40 +/- 2.40. IE, PZ, and DC were not significantly different from the MC control. Microscopic examination showed that adhesive failure, or complete delamination, did not occur between the compatible ceramic core and veneering materials. Failure primarily occurred near the interface with residual veneering porcelain remaining on the core. IE with Eris exhibited cohesive failure in both the core and the veneer. CONCLUSION: The bond strengths of 3 of the tested all-ceramic materials (IE, PZ, and DC) were not significantly different from the control (MC) group.

Color measurements as quality criteria for clinical shade matching of porcelain crowns.

STATEMENT OF PROBLEM: The ability of a dentist to select and communicate an acceptable shade match to a dental laboratory may be the most important factor in esthetic restorative dentistry. PURPOSE: The purpose of this study was to evaluate the use of instrumental color measurement in clinical shade matching of porcelain-fused-to-metal (PFM) and all-porcelain crowns. The relative effects of clinical and laboratory factors related to shade matching for PFM and all-porcelain crowns were also evaluated. MATERIALS AND METHOD: Forty patients treatment planned to receive PFM or all-porcelain crowns made up the study population. The patients were randomly divided into two groups for shade selection: conventional visual assessment and photocolorimetric analysis. At the preparation appointment, a photograph was taken of the target tooth along with four shade guide tabs selected by the two visual observers. The crown was fabricated by either visual selection or by the lowest E* values determined from the photographs and a spectrophotometer. The same dental laboratory fabricated all 40 restorations. At the cementation appointment, clinical criteria were used to evaluate anatomy/contour, surface texture, and the amount of glaze as it relates to color perception before the restoration was cemented. RESULTS: The mean E* between the reference tooth before preparation and the crown before cementation in the visual assessment group was 10.49 (+/- 14.6), whereas the mean E* in the photocolorimetric group was 8.99 (+/- 5.7). Analysis of data showed that the observers and the colorimetric technique were perfect (E* = 0) 41% of the time and varied (E* = 0.1 or higher) 59% of the time. Data collected further showed no significant difference or correlation between shade selection methods and the evaluated clinical criteria. CONCLUSIONS: These results provide evidence that there is no significant difference in shade selection using the conventional visual assessment by two experienced clinicians or the photocolorimetric technique. CLINICAL SIGNIFICANCE: The use of photocolorimetric analysis in shade selection can serve as a reliable alternative to conventional visual shade selection. This method is useful for clinicians who have difficulty with shade selection.

Capacidade inicial de vedaçäo em dentina de adesivo com e sem reforço de carga / Initial sealing capacity on the dentin of adhesives with and without filler reinforcement

O presente trabalho in vitro comparou a capacidade de selamento inicial de dois adesivos dentinários (com e sem carga), por meio de um critério clinicamente relevante. O resultado obtido mostra que o adesivo dentinário com carga apresentou, significativamente, melhor capacidade inicial de selamento do que o adesivo dentinário sem carga