Masking ability of monolithic CAD-CAM laminate veneers over different resin cement shades and substrate colors.

PURPOSE: To compare the masking ability of monolithic CAD-CAM veneers placed over different resin cement shades and substrate colors. MATERIAL AND METHODS: Veneers were milled of four different monolithic CAD-CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconia-reinforced lithium silicate ceramic (VS), and high translucency zirconia ceramic (YZ-XT). Veneers (n=9) were luted on natural tooth colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (white opaque or translucent). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (ΔE00) were calculated using CIEDE2000 formula and compared to perceptibility (P =0.81 ΔE00 units) and acceptability (AT=1.77 ΔE00 units) visual thresholds. Color variation data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (α=.05). RESULTS: The highest ΔE00 value was obtained in VMII group placed over discolored substrate, followed by the groups of Emax CAD, YZ-XT, and VS. The effect of material types on ΔE00 values was significantly observed when the veneers luted on discolored substrates using translucent resin cement (p<.05). CONCLUSIONS: Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD-CAM laminate veneers.

The effect of light sources and CAD/CAM monolithic blocks on degree of conversion of cement.

PURPOSE: To assess the degree of conversion (DC) and light irradiance delivered to light-cured and dual-cured cements by application of different light sources through various types of monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) materials. MATERIALS AND METHODS: RelyX Ultimate Clicker light-cured and dual-cured resin cement specimens with 1.5-mm thicknesses (n=300, 10/group), were placed under four types of crystalline core structure (Vita Enamic, Vita Suprinity, GC Ceresmart, Degudent Prettau Anterior). The specimens were irradiated for 40 seconds with an LED Soft-Start or pulse-delay unit or 20 seconds with a QTH unit. DC ratios were determined by using Fourier transform infrared spectroscopy (FTIR) after curing the specimen at 1 day and 1 month. The data were analyzed using the Mann-Whitney U test (for paired comparison) and the Kruskal-Wallis H test (for multiple comparison), with a significance level of P<.05. RESULTS: DC values were the highest for RelyX Ultimate Clicker light-cure specimens polymerized with the LED Soft-Start unit. The combination of the Vita Suprinity disc and RelyX Ultimate Clicker dual-cure resin cement yielded significantly higher values at both timepoints with all light units (all, P<.05). CONCLUSION: Within the limitations of this study, we conclude that the DC of RelyX Ultimate Clicker dual-cure resin cement was improved significantly by the use of Vita Suprinity and the LED Soft-Start light unit. We strongly recommend the combined use of an LED light unit and dual-cure luting cement for monolithic ceramic restorations.

A comparative study of marginal fit of copings prepared with various techniques on different implant abutments.

This study evaluated fabrication techniques of recently introduced all-ceramic copings' marginal adaptation on two different implant abutments with different finish lines. Five different copings were prepared (Casted chrome-cobalt metal coping, Zirkonzahn, Cercon, In Ceram Alumina and IPS e.max Press) on two cementable implant abutments with two marginal designs. Ten samples for each coping group were prepared (totally 100 samples). Copings were cemented to implant abutments and marginal gap measurements were done from 24 points with stereomicroscope and the datas were analyzed by the Kruskal-Wallis test before cementation. Cercon copings showed the lowest marginal fit scores and metal copings showed the highest scores. After cementation, all marginal gap values have been increased. All marginal gap values obtained from crown copings can be considered in clinically acceptable limits (<120 µm) except metal copings after cementation on abutment with 135 degrees shoulder group (123 µm).

Correction of malocclusion and oral rehabilitation in a case of amelogenesis imperfecta by insertion of dental implants followed by Le Fort I distraction osteogenesis of the edentulous atrophic maxilla.

BACKGROUND: Amelogenesis imperfecta refers a group of hereditary diseases affecting the teeth and can present a variety of clinical forms and appearances, compromising esthetic appearance. Amelogenesis imperfecta variably reduces oral health quality and can result in severe psychological problems. CASE PRESENTATION: We present the management of an amelogenesis imperfecta Angle class III malocclusion case with speech, esthetics and functional problems. This is an example of the rarely presented delayed eruption with multiple morphologic dental alterations and edentulous maxilla.There are only a few available reports in which this method is used method to correct sagittal discrepancies in edentulous patients.Our treatment plan consisted of a preoperative diagnostic and prosthodontics phase (including preparation of guiding prosthesis), followed by a surgical phase of Le Fort I osteotomy, distraction osteogenesis to correct the malocclusion, implant insertion and a follow up final restorative phase. CONCLUSIONS: Our treatment strategy attempts to serve patient needs, achieving function and esthetics while also minimizing the risk of reconstruction failure. Treatment not only restored function and esthetics, but also showed a positive psychological impact and thereby improved perceived quality of life.

Comparative evaluation of the effects of implant position, impression material, and tray type on implant impression accuracy.

PURPOSE: To evaluate the effect of implant position, impression, and tray material on the accuracy of implant impressions of edentulous arches with multiple implants. MATERIALS AND METHODS: Four experimental groups were produced; medium-viscosity polyvinyl siloxane (PVS) was used in 3 groups and polyether was used in 1 group. In PVS groups, different tray types were used; metal stock trays, custom acrylic tray, and full-arch perforated plastic trays. In polyether group, custom acrylic trays were used. The discrepancies in 3 dimensions were measured. RESULTS: The casts obtained exhibited small deviations (7.50-9.71 µm) from the master cast. There was no statistically significant difference between the polyether and PVS groups. Similarly, different tray materials did not produce any statistically significant discrepancies within the PVS groups. There was no significant difference among the groups when the accuracy of anterior implants were compared, but within-the-group comparisons showed that except group 1 (GR1), the posterior implants demonstrated more accuracy than anterior ones. CONCLUSIONS: Polyether and PVS can safely be used for the impressions of the edentulous arches with multiple implants and different tray types produce similar accuracy results.

Visual and instrumental evaluation of color match ability of 2 shade guides on a ceramic system.

STATEMENT OF PROBLEM: There is limited information on the visual and instrumental evaluation of color match between a natural tooth and a ceramic crown. PURPOSE: The purpose of this study was to evaluate the influence of 2 shade guides on color match, and to evaluate the relationship between color difference (ΔE) values and examiners' assessments of the color match in ceramic crowns. MATERIAL AND METHODS: Thirty-three subjects were selected for a ceramic crown restoration of the maxillary central incisor. Two crowns were fabricated with selected shades from Vitapan Classical and Vita Toothguide 3D-Master shade guides for each subject. The color values of maxillary central incisors, selected shade tabs, and corresponding crowns were measured with a spectrophotometer. The ΔE values between the natural teeth and the crowns and between the selected shade tabs and the corresponding crowns were calculated for each subject and compared with the Student's t test (α=.05). In addition, 3 examiners visually evaluated the clinical acceptability of each crown on a scale from 1 to 6. The agreement among the examiners was assessed with the Kappa test. The scores of examiners for both shade guides were analyzed with the Wilcoxon signed rank test (α=.05). RESULTS: The results revealed that the color difference values between the teeth and the crowns fabricated with the selected shades from the Vita Toothguide 3D-Master shade guide were significantly smaller than those of the Vitapan Classical guide (P=.003). Similarly, the color difference values between the selected shade tabs from the Vita Toothguide 3D-Master guide and the corresponding crowns were significantly smaller than those of the Vitapan Classical guide (P=.001). However, the ΔE values obtained for both shade guides were within the clinically acceptable range (ΔE<3.7). The kappa values implied moderate agreement among the 3 examiners. The median value of the examiners' scores was 2, which denoted an acceptable color match. In addition, the recorded scores of the 3 examiners showed that there was no significant difference in terms of the color match between the crowns fabricated with either of the 2 shade guides. CONCLUSIONS: The ceramic crowns fabricated with the Vita Toothguide 3D-Master shade guide resulted in a closer color match to the natural teeth than those of the Vitapan Classical guide. However, the ΔE values and the examiners' scores were within the clinically acceptable range for both shade guides.