Quantitative examination of factors influencing the colour reproduction ability of lithium disilicate glass-ceramics.

BACKGROUND: Effects of ceramic translucency, layer thickness, and substrate colour on the shade of lithium disilicate glass-ceramic restorations proved to be significant in several studies, however, quantitative, numerical results on the relationship between the colour difference and these parameters are still lacking. The purpose of this in vitro study was to quantitatively determine how the colour reproduction ability of a lithium disilicate glass-ceramic is affected by its translucency, layer thickness, and substrate colour. METHODS: Ceramic samples were prepared from A2 shade IPS e.max CAD blocks with high and low translucencies (HT and LT) in a thickness range of 0.5-2.5 mm (+/- 0.05 mm). Layered samples were acquired utilizing composite substrates in 9 shades; transparent try-in paste was used. The spectral reflectance of the specimens was assessed under D65 standard illumination with a Konica Minolta CM-3720d spectrophotometer. The CIEDE2000 colour difference (ΔE00) between two samples was analysed using perceptibility and acceptability thresholds set at 50:50%. Statistical analysis involved linear regression analysis and the Kruskal-Wallis test. RESULTS: An increase in the thickness of 0.5 mm reduced the ΔE00 of the HT samples to 72.8%, and that of the T samples to 71.1% (p < 0.0001). 7 substrates with HT and LT specimens had significantly different results from the mean (p < 0.05). A thickness of 0.5 mm is not sufficient to achieve an acceptable result at any level of translucency, while the low translucency ceramic at a thickness of 1.5 mm gave acceptable results, except for severely discoloured substrates (ND8 and ND9). CONCLUSIONS: The colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined.

Effect of thickness, translucency, and substrates on the masking ability of a polymer-infiltrated ceramic-network material.

OBJECTIVE: The aim of this in vitro study is to evaluate the masking ability of polymer-infiltrated ceramic-network materials (PICN) with different translucencies and thicknesses on multiple types of substrates. MATERIALS AND METHODS: Ceramic samples were prepared of VITA ENAMIC blocks in two different translucencies (2M2-T, 2M2-HT) in a thickness range of 0.5-2.5 mm (±0.05 mm). Layered specimens were obtained using composite substrates in nine shades and transparent try-in paste. Spectral reflectance of specimens was measured using a Konica Minolta CM-3720d spectrophotometer and D65 standard illumination. CIEDE2000 color difference (ΔE00 ) between two samples was evaluated using 50%:50% perceptibility and acceptability thresholds. Specular component of the reflection was examined with Specular Component Excluded (SCE) and Included (SCI) settings. Statistical evaluation was performed by linear regression analysis, Kruskal-Wallis test, and multiplicative effect analysis. RESULTS: An increase in thickness of 0.5 mm reduces ΔE00 of HT samples to 73.5%, of T samples to 60.5% (p < 0.0001). Five substrates with HT specimens, and three substrates with T specimens had significantly different results from average (p < 0.05). There is a significant difference between SCE and SCI data depending on the wavelength (p < 0.0001). CONCLUSIONS: Masking ability of PICN materials is influenced by the thickness and translucency of the ceramic, and by the substrate. Reflection of the examined PICN material is characterized by both diffuse and specular reflection. CLINICAL SIGNIFICANCE: Although PICN materials have been available on the market for 10 years now, there is a lack of information regarding their masking ability. Acquiring in-depth data and thereby practical experience of the factors affecting the esthetics of PICN materials is essential for creating perfectly lifelike restorations.

Effects of substrate, ceramic thickness, translucency, and cement shade on the color of CAD/CAM lithium-disilicate crowns.

OBJECTIVE: The aim of this in vitro study was to evaluate the effects of substrate colors, different levels of ceramic thickness and translucency, and cement shades on the color difference from a reference color of lithium-disilicate crowns. MATERIALS AND METHODS: A premolar tooth preparation was made on a study model for 1.0 and 1.5 mm thick full-ceramic crowns. Digital impressions were taken (3Shape TRIOS) and crowns designed in a CAD program (DentalDesigner). Shade A1 crowns were milled (Everest, Kavo) from high-translucency (HT) and low-translucency IPS e.max (Ivoclar Vivadent) blocks. Twelve substrates were made of different colors and materials (Natural Die Material, Co-Cr, zirconia, and gold-colored alloy). Three different shades of try-in pastes were used to simulate the effect of cements (Variolink Esthetic try-in paste; Ivoclar). Shade measurement was done three times for each crown by a spectrophotometer (VITA Easyshade Advance); averages were compared to a reference crown (A1, HT, 1.5 mm, ND2 abutment, neutral try-in paste) with ΔE00 (CIEDE2000, according to the CIE latest standard) calculated. RESULTS: All the examined parameters influenced the ΔE00 of the crowns. The weakest effect was exerted by the try-in paste. CONCLUSIONS: All examined parameters influenced the final color of e.max CAD lithium-disilicate ceramic crowns. CLINICAL SIGNIFICANCE: Matching the shade of ceramic crowns to the natural tooth color is a great challenge in dentistry. To meet patients' increasing esthetical expectations, CAD/CAM methods are very popular for full-ceramic crowns. However, several factors such as the shade of the abutment, luting cement color, ceramic thickness, and translucency may influence the final color. Our objective was to measure the optical effect of these factors on the final shade of CAD/CAM lithium-disilicate ceramic crowns.

Prosthetic rehabilitation of a patient with ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome through a hybrid workflow: A case report with 2-year follow-up.

AIM: Ectrodactyly-ectodermal dysplasia-cleft lip/palate (EEC) syndrome is a rare genetic disorder that affects ectodermal derived structures, including teeth, nails, hair, and sweat glands. Prosthetic rehabilitation of patients with EEC syndrome is essential towards improving their overall quality of life. METHODS AND RESULTS: In the case shown, a telescopic retained overdenture was made on the lower jaw based on digital impression of a patient with EEC syndrome associated with cleft lip and cleft palate. Due to the congenital anomalies and limited mouth opening, the impression was taken with intraoral scanner, and after designing the telescopes on the digital model, the primary and secondary telescopes were confectioned by selective laser sintering. CONCLUSION: Combining digital dental technology and conventional clinical prosthetic treatment methods, results in a well-functioning overdenture even in such complicated situations. The prosthodontic rehabilitation of patients with ECC helps to restore the masticatory and phonetic functions, increases the patient's self-esteem, and prevents further psychological trauma caused by hypodontia.

[Use of questionnaires in screening for risk factors in the dental care of elderly patients]. / Kérdoív használata rizikófaktorok kiszurése céljából idoskorú páciensek kezelése esetén.

The medical and dental history is one of the crucial part of the routine dental practice. According to a survey performed in 2001 27% of the total Hungarian population was above the age of 60. The prognosis forecasts an increasing tendency in life expectancy and an even higher percentage of elderly population in the foreseeable future. Due to the increasing life expectancy the risk for complications of common dental treatments is also increasing. More care and attention should be paid to anticipate the occurrence of sudden complications during dental treatment that might also be a life threatening condition. In 1941 the American Dental Association drew up a questionnaire based on the risk groups established by the American Society of Anaesthesiologists (ASA). In 1993 K.J.M. de Jong et al. presented the results of their experience with the clinical application of these questionnaires. Based on their studies the Dental Working Group of the Health Committee of the European Council recommended the European application of this questionnaire. The major objective of our investigation was to evaluate how this questionnaire--developed by ASA--can assist the proper registration of the medical history in dental practice. Our survey also investigated how the risk groups distributed among the subjects. The data of 207 randomly selected individuals from the patient pool of the Dental Faculty of Semmelweis University were processed. The data of risk groups distribution is outlined here: ASAI:35,8%, ASAII:24%, ASAIII:17%, ASAIV:23,2%. In the age group 60+ the following distributions were obtained: ASAI:20,9%, ASAII:13,2%, ASAIII:24,2%, and ASAIV:41,7%. The results of this survey also confirmed that the occurrence of ASAIII and ASAIV risk scores increased in the age of 60+. Consequently the number of patients whose treatment plan should be modified due to health risk factors is also increasing. It can be stated that the ASA classification is appropriate to inform the dentist about the general physical status and health problems of the patients that may influence the dental treatment.