Material and clinical considerations for full-coverage indirect restorations

Because dental ceramics have been used for decades and continuously improved over the years, there is a plethora of information regarding their material characteristics, applications, and contraindications. Each restorative ceramic material demonstrates benefits and disadvantages, making it difficult for dentists to research, retain, and apply the ideal material for individual restorations and/or combination cases. This article outlines the applications and benefits of dental ceramics in general and examines and reviews the current ceramic alternatives available for restorative dentistry today. It also discusses the material composition and properties of a recently introduced new classification of indirect material: resin nano-ceramic.

Spectrophotometric evaluation of color match of three different porcelain systems for all-ceramic zirconia-based restorations

PURPOSE

To determine by a spectrophotometric analysis the variations in color between the intended and the fabricated shades of three different porcelain systems when applied in a standardized thickness on a zirconia core.

METHODS

Three porcelain systems for zirconia based restorations, Ivoclar IPS e.max Ceram, VITA VM9, and Creation Zi-F were tested. Nine disc-shaped (15 mm diameter, 0.5 mm thickness) specimens of VITA YZ zirconia core per group were made comprising a total of 27 discs. Three different shades (A2, A3, A4) of the Vitapan Classical shade guide were investigated. The porcelain veneer total thickness was set at 1.0 mm in all groups. The porcelain stratification was made by applying calibrated layers of porcelain. Thicknesses of single porcelain layers were calculated from drawings retrieved from the manufacturers' instructions. Color parameters (L*, a*, b*) of veneered specimens were measured by a clinical spectrophotometer. Color differences (deltaE) were calculated using a color difference formula. Two-way ANOVA and Tukey's test were used to analyze the data.

RESULTS

The mean color differences for the three ceramic systems, Ivoclar IPS e.max Ceram, VITA VM9 and Creation Zi-F were respectively 4.1, 2.7 and 3.2, regardless of the shades. VITA VM9 resulted in the best average shade matching among the porcelain systems, even if results with shade A3 were considerably worse than shades with A2 and A4 (P<0.05). Color matching appeared not to be shade dependent (P>0.05) among the tested shades.

A three-die cast technique for duplicating free gingival form in zirconia crowns: two case reports

This report describes a duplication technique of free gingival form from a provisional restoration to a zirconia crown. Three die casts were manufactured from a silicone impression with an acrylic resin ring tray. The first die cast was for the zirconia framework, the second for the provisionalized transfer coping, and the third for relining the provisional restoration. A free gingival impression was taken using a provisionalized transfer coping, and a soft gingival cast was manufactured. The depth of free gingival transparency was measured using a zirconia shade plate. Then, the zirconia framework was customized to allow for subgingival porcelain space. This technique seems to contribute to the clinical-laboratory interface in computer-aided design/computer-assisted manufacture restorations.

Conservative restoration of a traumatically involved central incisor

The use of a direct composite material known for excellent polishability, polish retention, and wear resistance is described in this case of a fractured central incisor restoration. The method used enabled the clinician to conserve tooth structure and maintain full control of the outcome while creating an esthetically imperceptible, reliable, and durable restoration for a young male patient. Emphasized in this case are the techniques of layering, contouring, and polishing of a nanocomposite used to maximize esthetics and meet patient expectations. To further ensure imperceptibility, the author recommends first facilitating color shade selection for both body and dentin-especially in two-shade or multiple-shade restorations-by placing the composite in its planned area of the restoration and curing it in its proper thickness to allow a preview and recipe map.

Restoration of a fractured central incisor

The treatment of a traumatically damaged single central incisor poses significant challenges relative to function and esthetics to the restoring clinician. Providing a good long-term prognosis is paramount when determining whether to maintain or extract a structurally compromised tooth. Successful restoration demands timely and thorough risk assessment along with excellent communication with both the patient and the laboratory fabricating the restoration.

[Tooth color matching systems and communication with dental laboratory in indirect restorations: 2011 update]

There has been many technological developments in the last decade. Today's shade-matching technologies have been developed in an effort to increase the success of color matching, communication, reproduction and verification in clinical dentistry and, ultimately, to increase the efficiency of esthetic restorative work within any practice. In general, the output of the color measurements can be classified and specified in several ways. The most common systems for describing color are Munsell's System and the international Commission on Illumination (CIE) L a b color system. Albert Munsell described color as a three-dimensional phenomenon. He described the three dimensions as hue, value (brightness), and chroma (saturation). Visual colour determination by comparison of teeth and shade guides is the most frequently applied method in dentistry. Vitapan Classical (Vita Zahnfabrik, Germany) and its derivations(evidence-based Vitapan 3D-Master shade guide and Linearguide) are the most commonly used shade guides. However, several factors can influence consistency of visual colour selection and specification: individual colour matching ability may vary, the colour perception of any individual may show temporal variation, the range of shades available is inadequate and does not cover the complete colour space of natural teeth, the shade guide tabs are not systematically distributed in their colour space, and changes in lighting conditions can cause alterations in perceived colour. instruments for clinical shade-matching encompass spectrophotometers, colorimeters and digital imaging systems. It can be concluded that different devices have different accuracy and precision. Colorimeters are significantly less reliable than spectrophotometers and digital cameras. Benefits and limitations exist, and the clinician must consider how the technology relates to expectations and needs. Combination of visual colour determination (Vitapan 3D-Master shade guide and Linearguide) with digital cameras and electronic devices (spectrophotometers) increase chances for successful shade matching.

[Evaluation of colour vision according to type of implanted artificial foldable intraocular lens]

PURPOSE

The aim of research was comparing the colour vision of patients with blue light filtering artificial lens to the patients with implant without blue light filter.

MATERIAL AND METHODS

99 patients (120 eyes) divided on three groups were examined. 40 patients (40 eyes) after cataract surgery with implantation of blue light filtering lens were the first group. 39 patients (40 eyes) who had implanted lens without filter were the second group. 20 patients (40 eyes) with own transparent lens were the third group. Farnsworth-Munsell 100 Hue test was used in research. Each patient made test on thirtieth day after cataract surgery.

RESULTS

Following average total error score (TES) values in groups were observed: the first group--60.66, the second group--83.71, the third group--61.55. Average axis of disorder in blue-yellow range was following: patients after cataract surgery with implantation of blue light filtering lens--5.48, patients with implant without blue light filter--7.28, control group--5.74.

CONCLUSIONS

1. Kind of artificial intraocular lens has meaning in colour vision at pseudophakic patients. 2. Blue light filter of artificial intraocular foldable lens advantageously effects perception of colours. 3. Lack of blue light filter in artificial intraocular lens gets worse colour vision especially in blue-yellow range.

[Evaluation on the application of mechanical toothguide training box to chromatics teaching of prosthodontics]

OBJECTIVE

To evaluate the effectiveness on the application of mechanical toothguide training box (TTB) to chromatics teaching of prosthodontics.

METHODS

12 preclinical undergraduate students were chosen to participate in the VITA 3D-Master shade-matching system simulant toothguide training process using Linearguide Training Box program of TTB. Toothguide Trainer program considered as a test was performed on the trained undergraduate students group, the postgraduate students group as well as the clinical prosthodontists group with under 5-year clinical experience. The test scores, elapsed time and the coincidence of chromatics single factor matching were recorded each time, the shade-matching efficiency was calculated. The data was analyzed with SPSS 13.0 software.

RESULTS

The shade-matching efficiency of undergraduate students trained by TTB (64.03 +/- 18.82) was significantly higher than before (P < 0.05), higher than the postgraduate students group and the clinical prosthodontists group (P < 0.05). The coincidence of chromatics single factor matching of trained undergraduate students were 64.64% (lightness), 88.57% (chroma), 87.70% (hue).

CONCLUSION

TTB is a effective tool for shade-mathing practice in chromatics teaching of prosthodontics. The trained undergraduate students are less sensitive in lightness-matching.

Successful strategies for matching one or two indirect restorations to natural dentition

One of the most difficult and noble undertakings of a dental restorative team is to provide an indirect restoration for a compromised tooth surrounded by otherwise healthy, natural dentition. Matching one or two indirect dental restorations to adjacent healthy teeth is a herculean task for both the dentist and laboratory technician. The team must be knowledgeable of the natural dentition's characteristics to best mimic and recreate those same characteristics in a man-made restoration. Knowledge of principles in smile design, dental anatomy, color, characterization, material selection, doctor-technician communication, and clinical acumen are necessary to achieve a successful outcome when matching one or two indirect restorations to natural dentition.

Custom shade matching: fine-tuning and patient communication lead to success

Shade matching is a sometimes difficult process that involves a variety of colors and characteristics. Couple this with a patient base that often encompasses a wide range of ages, and final restorations can frequently require adjustment or repair because they have failed to match the patient's natural teeth. In this article the author relates many of his own custom shade-taking experiences in an effort to help dental technicians improve their color-matching strategies and avoid costly mistakes.

Effects of air-polishing powders on color stability of composite resins

OBJECTIVES

The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials.

MATERIAL AND METHODS

Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p<0.05).

RESULTS

According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil.

CONCLUSION

Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing after air-polishing.

Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging

The purpose of this study was to evaluate the color stability of a maxillofacial elastomer with the addition of a nanoparticle pigment and∕or an opacifier submitted to chemical disinfection and artificial aging. Specimens were divided into four groups (n = 30): group I: silicone without pigment or opacifier, group II: ceramic powder pigment, group III: Barium sulfate (BaSO(4)) opacifier, and group IV: ceramic powder and BaSO(4) opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was done three times a week during two months. Afterward, specimens were submitted to different periods of artificial aging. Color evaluation was initially done, after 60 days (disinfection period) and after 252, 504, and 1008 h of artificial aging with aid of a reflection spectrophotometer. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). The isolated factor disinfection did not statistically influence the values of color stability among groups. The association between pigment and BaSO(4) opacifier (GIV) was more stable in relationship to color change (△E). All values of △E obtained, independent of the disinfectant and the period of artificial aging, were considered acceptable in agreement with the norms presented in literature.

Esthetic provisionalization for a combined porcelain veneer and anterior single crown case

This article presents a technique for the fabrication of provisional veneers when a single full-coverage anterior restoration is involved. A case that includes seven porcelain veneers and one all-ceramic crown is discussed.

[Influence of SiO2 films on color reproduction of Ni-Cr alloy porcelain crowns]

OBJECTIVE

To study whether SiO2 films will influence the color of Ni-Cr metal ceramic restorations.

METHODS

For the film plating experimental group, Sol-gel method was employed to apply SiO2 films to the surface of the Ni-Cr copings, while no coating was applied for the non-film-plating control group. Veneering porcelains were then applied subsequently, and a total of 12 B2-colored maxillary incisor metal ceramic crowns were fabricated with 6 crowns in each group. A ShadeEye Ncc computer-aided colorimeter was employed to measure the shade of the samples, as well as 6 B2(Vitapan classical vita color tabs) shade standards. The color was expressed as C1E-1976-Lab coordinates.

RESULTS

There was a statistically significant color difference between all metal ceramic crowns and the B2 shade standards (delta E>1.5). The L*, a*, b* values of all crowns were higher than those of the B2 shade standards, and the crowns were typically yellower or redder. While neither significant color difference nor difference in shade values was observed between the film plating experimental group and non-film-plating control group (delta E<1.5).

CONCLUSION

SiO2 films applied to the Ni-Cr copings by means of Sol-gel technique do not impact the final color of the metal ceramic restorations.

Dentist-technician collaboration in the digital age: enhancing outcomes through photography, teamwork, and technology

The cornerstone of a strong and successful dentist-technician relationship is communication. High-level collaboration across distances requires modern technology to communicate expectations, potential outcomes, and limitations. Carefully calibrated digital photography is an essential element in this inherently artistic process. This ensures a system of checks and balances to minimize the potential for miscommunication and remakes. Forthcoming technologies will allow dentist-technician teams to reach ever-greater levels of collaboration.

[Application of digital photography in color matching in dentistry]

OBJECTIVE

To develop a new color matching method in dentistry by application of digital photography.

METHODS

Digital photographs were obtained of Vitapan 3D-Master shade guide and natural teeth under the same condition, the L*a*b* values of each digital photography were assessed and analyzed by Photoshop CS4.

RESULTS

The Vitapan 3D-Master shade guide was divided into 5 groups, the L* values were similar in each group, but decreased from group 1 to 5. The a* values of L1.5 and L2.5 were minimum, R1.5 and R2.5 were maximum and M1-M3 were intermediate. Compared with Vitapan 3D-Master shade guide, the L*a*b* values of natural teeth were higher.

CONCLUSION

Digital photography can basically reflect the color of Vitapan 3D-Master shade guide, and provides a reference for color matching in dentistry.

Esthetic restoration of maxillary incisors using CAD/CAM chairside technology--a case report

High-quality esthetic veneers can be produced in a single treatment session only by means of chairside CAD/CAM technology. With efficient therapy, the duration of the relatively long treatment cycle can be optimized: planning casts and a diagnostic wax-up are steps that simplify therapy decisions, the same as with veneers produced by laboratories. After production of a mock-up and preparation of the teeth, removable composite veneers can be prepared and gradually replaced by ceramic veneers. Modern, three-dimensional presentation by use of the Cerec 3D system facilitates construction of veneers seen in relation to the other teeth. A very helpful aspect is that the mock-ups can be adjusted to patients' needs during the complete production process. After individualization by a dental ceramic technician, there is no recognizable esthetic difference from veneers produced by a laboratory.

Effect of abutment tooth color, cement color, and ceramic thickness on the resulting optical color of a CAD/CAM glass-ceramic lithium disilicate-reinforced crown

STATEMENT OF PROBLEM

A dark-colored prepared abutment tooth may negatively affect the esthetic outcome of a ceramic restoration if the tooth is restored using translucent enamel-like ceramic materials.

PURPOSE

The purpose of this study was to evaluate the cumulative effect that the tooth abutment color, cement color, and ceramic thickness have on the resulting optical color of a CAD/CAM glass-ceramic lithium disilicate-reinforced crown.

MATERIAL AND METHODS

A CAD/CAM glass-ceramic lithium disilicate-reinforced monolithic crown (IPS e.max CAD LT) was fabricated. Three possible crown restoration variables were tested in vitro. The procedure examined 4 prepared abutment tooth colors (light, medium light, medium dark, and dark), 2 cement (Variolink II) colors (translucent and opaque), and 4 ceramic thickness values (1.0 mm, 1.5 mm, 2.0 mm, and 2.5 mm). The color of each combination was measured using a spectrophotometer, and the average values of the color difference (ΔE) were calculated. The data were analyzed with a 3-way ANOVA (tooth abutment color, ceramic thickness, and luting agent) and Tukey's HSD test (α=.05), which evaluated within-group effects of the tooth abutment color to the ΔE at each ceramic thickness.

RESULTS

The ΔE values of a CAD/CAM glass-ceramic lithium disilicate-reinforced crown were significantly influenced by the tooth abutment color (P<.001), cement color (P<.001), and ceramic thickness (P<.001). Significant interactions were present among these 3 variables (P<.001). A dark-colored abutment tooth demonstrated the greatest ΔE values relative to other variables tested. An increase in ceramic thickness resulted in a significant decrease in ΔE values (P<.01). The ΔE values were slightly decreased when the crowns were cemented using the opaque cement.

CONCLUSIONS

This study demonstrated that underlying tooth abutment color, cement color, and ceramic thickness all influence the resulting optical color of CAD/CAM glass-ceramic lithium disilicate-reinforced restorations.

[Effects of cleaners on the color stability of prosthesis silicone rubbers]

OBJECTIVE

To evaluate the effect of different cleaners on the color stability of two silicone rubbers used for maxillofacial prosthesis, and to provide recommendations for clinical use.

METHODS

Thirty skin-color columniform specimens (12 mm diameter, 10 mm height) of two silicone rubber (A:A-2000; Z:ZY-1) were prepared, randomly divided into 6 groups according to the table of random number, and cleaned with the following solutions: isopropyl alcohol (I), three kinds of denture cleaners (P: Polident, S: Steradent, C: Cleansoft) and distilled water (D), simulating the total immersion time of 1 year (1, 15, 10, 3 and 10 min each time respectively). Control group was kept in dark place without treatment. The L(*), a(*), b(*) value were tested before and after immersion. Then color difference value was calculated.

RESULTS

Color differences were different among groups. Color difference in group I (A: 2.15, Z: 2.00) were significantly greater than that in any other group. There were no significant differences between groups using denture cleaner P (A: 0.36, Z: 0.36), C (A: 0.42, Z: 0.37) and S (A: 0.33, Z: 0.38), and group D (A: 0.22, Z: 0.23).

CONCLUSIONS

Isopropyl alcohol causes the most severe fading, and denture cleaners and distilled water cause obscure fading.

[Clinical assessment of acceptability of shade mismatch of infiltrated alumina ceramic crowns]

PURPOSE

To measure and evaluate the acceptability of shade mismatch of infiltrated alumina ceramic crowns directly in clinic.

METHODS

Ten cases with restoration of hot casting alumina ceramic crown were collected in clinic. L*, a*, b*, C, H, ΔE values of hot casting alumina ceramic crowns and corresponding natural teeth in natural light were surveyed and calculated, then analyzed with CIE1976L*a*b* color system, digital photography and Photoshop CS2. All statistical analyses and calculations were completed in paired t test with SAS6.12 software package.

RESULTS

In cervical 1/3 region, significant statistical difference in lightness, a*, hue angle parameter value between alumina all-ceramic crown and natural tooth (P<0.01) was found; in middle 1/3 region, significant difference in a*, b*, saturation parameter value (P<0.01) existed; in incisory 1/3 region, the parameters had no significant difference (P>0.05). To parameter ΔE, there was significant difference in every region, but it was in the acceptable range.

CONCLUSIONS

The acceptability of shade mismatch is about 6 ΔE units, we can analyse the color difference between the restoration and natural teeth directly in clinic through symmetry of central incisor.

[Comparative study on spectrophotometric and visual methods for color stability of denture base resin]

OBJECTIVE

To explore the relationship between the spectrophotometric and visual methods in evaluating the color stability of denture base resin, and determine the threshold color difference of denture base resin in the spectrophotometric method.

METHODS

Two kinds of denture base resin were respectively fabricated into 33 specimens whose color differences varied from indistinguishable to obvious. Each of the specimens was assessed respectively by 30 human observers and a SP62 spectrophotometer. The results of visual assement were recorded as "indistinguishable change", "light change" or "severe change", while the spectrophotometric color differences (ΔE) were calculated. In each group, a logistic curve was explored to determine the relationship between the color difference (ΔE) and the ratio of "severe change".

RESULTS

The R squares of logistic curves were 0.93 and 0.94 respectively. The threshold color differences in the spectrophotometric method were 2.87 and 2.82 respectively.

CONCLUSIONS

A high relevance between the spectrophotometric and visual methods in evaluating the color stability of denture base resin was found. The threshold color differences for different color denture base resins were similar.

[Infinite optical thickness of dentine porcelain of IPS E.max A color series]

OBJECTIVE

To determine the infinite optical thickness of dentine porcelain of IPS E.max A color series.

METHODS

Cylindrical dentine porcelain specimens of the IPS E.max A color series were prepared with a diameter of 13 mm and thickness of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 mm. The chromatic value of all the specimens was determined with CM-5 spectrometer against standard black and white background. The chromatic aberration (deltaE) was calculated by regression equation.

RESULTS

The infinite optical thickness of dentine porcelain of the IPS E.max A color series ranged from 2.341 to 3.333 mm for a deltaE of 1.0, and from 2.064 to 2.904 mm for a deltaE of 1.5. As the chromaticity or thickness increased, the influence by the background color decreased, and the color of specimens became gradually close to the intrinsic color.

CONCLUSION

The thickness of the background dentine porcelain specimens must exceed its infinite optical thickness to represent the intrinsic color and avoid the influence by the extrinsic color.

Zirconia-based fixed partial dentures: a clinical review

Ceramics have a long history in fixed prosthodontics of achieving optimal esthetics. Yttrium tetragonal zirconia polycrystal (Y-TZP)-based systems are a recent addition to the high-strength, all-ceramic systems used for crowns and fixed partial dentures. CAD/CAM-produced, Y-TZP-based systems are in considerable demand in esthetic and stress-bearing regions. The highly esthetic nature of zirconia coupled with its superior physical properties and biocompatibility have resulted in restorative systems that meet the demands of today's patients. Undoubtedly, these systems are considered to be prospective replacements for metal-ceramic restorations. This article reviews relevant contemporary literature regarding all-ceramic materials and systems and discusses their material properties, biocompatibility, advances in cementation, and more with special emphasis on clinical survival. The article also aims to provide recommendations for their use.

A survey on variability in shade selection by practicing dentists

PURPOSE

To evaluate the variability in shade selection for general practitioners (GPs) and postgraduate (MDS) practitioners and to assess if a shade selection bias exists.

MATERIALS AND METHODS

2070 samples of the chosen shade(s) by 31 GPs and 18 MDS practitioners in the form of work authorization forms and slips were collected from dental laboratories. The mouth was divided into four quadrants: maxillary anteriors and posteriors, and mandibular anteriors and posteriors. The data was grouped and analyzed.

RESULTS

The same shade or combination was repeated by the GPs and the MDS practitioners 38% and 35% of the time, respectively. The GP group prescribed a single shade in 84% of cases and a combination of two shades per tooth in 14% of cases, in contrast to the MDS practitioners, who prescribed a single shade in 51% of cases and two shades in 47% of cases.

CONCLUSION

A shade selection bias exists among both general and MDS practitioners, as a particular shade or combination was repeated a significant number of times. However, MDS practitioners use a combination of two shades more frequently than general practitioners, who rely mostly on a single shade for a tooth.

Complications and management of cosmetic anterior chamber iris implants

PURPOSE

To report the management of complications due to cosmetic iris implantation.

DESIGN

Interventional case report.

METHODS

A 27-year-old female underwent bilateral anterior chamber NewColorIris implants in Panama to cosmetically change her eye colour. Two weeks later she presented as an eye emergency in London with corneal decompensation, raised intraocular pressure and significantly reduced vision. Bilateral explantation was performed with good postoperative recovery.

RESULTS

Three months following explantation, visual acuity had normalized and intraocular pressure was within the normal range without medication.

CONCLUSIONS

Cosmetic iris implantation can lead to potentially sight threatening complications. This is the first case to be reported in the United Kingdom. There is a lack of published safety data and their cosmetic application should be cautioned against.

Evaluating tooth color matching ability of dental students

Visual shade matching has remained a skill acquired through clinical experience. The purpose of this study was to evaluate the shade matching ability of dental students as they progress through their education. Sixty-five students, representing four levels of experience by year enrolled in dental school, participated in this study. Students were given a preclinical shade tab matching task. They were also asked to choose the best shade match for a natural tooth in each of three patients. The natural tooth shade matching task was designed to have simple, moderate, and complex cases to match. The frequency of correct answers was compared across samples across the four levels of fundamental tab match ability and clinical experience. On average, 51 percent of the students were able to match the correct shade tab in the matching task in a bench setting. For the natural tooth color matching task, 49.2 percent of the students selected the clinically acceptable color matched shade tabs (ΔE*≤2.69). Although there was no statistically significant difference across the levels of fundamental ability and experience, rates of correct answers for natural tooth color matching progressively improved for the complex case from year 1 to year 4. This study reveals that, for complex cases, education and knowledge of color science combined with clinical experience improve students' ability for color matching in a clinical setting.

Revisiting the design of minimal and no-preparation veneers: a step-by-step technique

The concept of minimal preparation is more than 25 years old. Interest in conservative treatments is being revisited as dentistry embraces thinner ceramic veneers and adhesive bonding agents that keep preparations in enamel. Experience and professional knowledge help determine appropriate treatments based on patients' clinical situations and esthetic demands. This article reviews the veneer modality, its role as a conservative treatment, and the protocol to be implemented to ensure proper treatment planning and material selection.

Rehabilitation of the nose using CAD/CAM and rapid prototyping technology after ablative surgery of squamous cell carcinoma: a pilot clinical report

Restoration of a nasal defect after ablative surgery for squamous cell carcinoma necessitates replacing the missing volume and anchoring a prosthesis to the patient's face. This report describes the failure of plastic reconstructive surgery after ablation of a squamous cell cancer of the nose and the esthetic and functional restoration of the patient with a nasal prosthesis. The process of making an implant-supported prosthesis using digital technology, including digitized anatomic models from a "nose library," and the rapid prototyping of the mesiostructure for bar anchorage and of the mold for silicone processing are presented.

Clinical evaluation of two packable resin-based composite restorations: a three-year report

This randomized clinical trial sought to evaluate the performance of two packable composites over a period of 36 months. A total of 39 Class I and II restorations were placed in the permanent teeth of 20 patients. Using United States Public Health Services criteria, two investigators evaluated the restorations immediately after placement and again after 12 and 36 months, examining color match, marginal discoloration, marginal integrity, recurrent caries, proximal contact, anatomical shape, surface texture, and postoperative sensitivity. It was concluded that the packable composites evaluated showed satisfactory clinical performance after three years.

Effect of surface sealant and repolishing procedures on the color of composite resin exposed to cigarette smoke

This study evaluated the effect of cigarette smoke on the color of composite resins, with and without the application of a surface sealant and before and after the restorative material was repolished. Twenty composite resin specimens were divided into two groups (n = 10); one of which received a surface sealant. Both groups were exposed daily to the smoke of 20 cigarettes. Color analyses were performed using a spectrophotometer at different intervals: prior to cigarette smoke exposure (baseline), 21 days after cigarette smoke exposure, and after the specimens were repolished using aluminum oxide discs. Cigarette smoke caused a decrease in lightness (L*), especially in samples that received the sealant (p = 0.014). At 21 days, there was an increase in yellow pigment for both groups, with higher values (p = 0.00001) and predominant red pigmentation in the samples that received sealant. An increase in lightness and a decrease in yellow pigments (p < 0.05) were reported in both groups after repolishing. Cigarette smoke significantly altered the color of the composite resin (DeltaE > or = 10.34), especially in the specimens that received the sealant. In this study, the sealant tested intensified cigarette staining, and although repolishing decreased surface pigmentation, it was unable to restore the original color of the composite resin.

Color management of porcelain veneers: influence of dentin and resin cement colors

OBJECTIVE

Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers.

METHOD AND MATERIALS

A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and DE values were calculated against the preselected target color (A1). DE greater than 3.3 was considered as a significant color mismatch detectable by the human eye.

RESULTS

The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured DE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match.

CONCLUSION

Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match.

Effect of CAD-CAM porcelain veneers thickness on their cemented color

OBJECTIVE

To determine the effect of thickness of porcelain veneers constructed from CAD-CAM on their final color when two resin cements were used.

METHODS

Buccal surfaces of extracted sound human molars with shade 3M2 [verified using digital spectrophotometer (Vita Easyshade-Vident)] were reduced to expose flat enamel surfaces. CAD-CAM blocks (Vitablokcs Mark II) of the same shade were sectioned into three groups of 0.3, 0.5 and 0.7mm thickness. Each group was subdivided into two subgroups; one subgroup was cemented to enamel using an etch-and-rinse resin cement (Calibra/Prime and bond-NT, Dentsply) and the other was cemented to enamel using a self-etching resin cement (Panavia-F, Kuraray). The shade of the two resin cements was "light". Change in color (ΔE) between the selected shade (3M2) and the resulted shade was measured for each specimen using a digital spectrophotometer (Vita Easyshade-Vident). Means and SDs were calculated and data was statistically analyzed using ANOVA and post hoc tukey's.

RESULTS

Change in color (ΔE) between the selected and the produced shade for the Calibra subgroups was 2.8 (0.3) for the 0.3mm, 1.67 (0.2) for the 0.5mm thick specimens and 1.26 (0.3) for the 0.7mm. Panavia F subgroups showed ΔE of 2 (0.4) for the 0.3mm, 1.13 (0.23) for the 0.5mm thick specimens and 1.21 (0.31) for the 0.7mm. The 0.7mm subgroups showed no significant difference in color change among the two cements (P>.05), however, Calibra resulted in significantly higher change in color values for the 0.5mm thick specimens (P<.05). In spite of the presence of significant difference for the Calibra 0.5mm thick subgroup, the color change was considered to be within the clinically acceptable range. The 0.3mm showed high significant difference for the two tested cements with the Panavia showing less change in color and Calibra showing clinically detectable change in color.

CONCLUSION

Increasing porcelain veneer thickness from 0.5 to 0.7mm did not significantly affect the final color of cemented veneers. Whilst the color was significantly affected at the thickness of 0.3mm.

Influence of framework color and layering technique on the final color of zirconia veneered restorations

OBJECTIVE

To investigate the influence of colored zirconia frameworks on the overall color match of zirconia-veneered restorations.

METHOD AND MATERIALS

Identical natural and colored zirconia frameworks (Cercon Base, Degudent) were layered using a veneer ceramic (IPS e.max Ceram Dentin, Ivoclar Vivadent) applied either directly on the frameworks, over a thin layer of a masking liner (IPS e.max ZirLiner 1), or over a layer of a deep chroma dentin (IPS e.max Deep Dentin) of the required target color, A1. Color parameters were obtained using a spectrophotometer (Spectro Shade Micro, MHT) and were used to calculate color difference value with the preselected required color (A1 tab according to Vita Classical shade guide). Color difference value < 2.2 was considered a clinically acceptable color match.

RESULTS

Only three combinations of tested variables had an acceptable color match compared with the target color: colored zirconia frameworks with liner material or deep chroma dentin and white zirconia frameworks directly layered with the veneer ceramic (P < .001), all tested against a black background. The combination of yellow zirconia with deep chroma dentin over a white background produced a yellowish color shift, while white zirconia frameworks with either liner or deep chroma dentin were brighter and less yellow than the target color (A1).

CONCLUSIONS

When properly veneered, colored zirconia frameworks could produce clinically acceptable color match and have the capacity to mask a dark background such as a dark tooth or core buildup material.