Effect of newly developed pigments and ultraviolet absorbers on the color change of pigmented silicone elastomer.

AIM AND OBJECTIVE: The aim and objective of the study is to evaluate effect of ultraviolet (UV) stabilizer (UV absorber Chimassorb 81) on color change of pigmented silicone elastomer when commercially available (red and yellow), and newly developed pigments (sicotrans red and sicopal brown) were used. MATERIALS AND METHODS: Two commercially available pigments - red (P112 Brilliant Red) and yellow (P106 Yellow) and two newly developed pigments - sicotrans red and sicopal brown were studied. In total eight groups made up of nine samples each were fabricated using elastomer with the combinations of the above pigments and UV stabilizer (Chimassorb 81). Groups 1, 3, 5, and 7 contain elastomer in combination with sicotrans red, sicopal brown, yellow and red pigments, respectively. Similarly, groups 2, 4, 6, and 8 along with elastomer and pigments (sicotrans sed, sicopal brown, yellow and red, respectively) contain the UV stabilizer (Chimassorb 81). Samples were subjected to aging in an accelerated weathering chamber (Weather-Ometer). Color values CIE (Commission Internationale d'Eclairage) L*, a*, and b * were measured at baseline and after 1000 h of weathering. Change in color (Delta E) was calculated. RESULTS: All groups showed a significant color change at 1000 h. Groups 1, 2, 3, and 4 showed a statistically significant less change in both colors (sico trans red and sicopal brown) compared to groups 5,6,7, and 8 (commercial pigments-Red and Yellow). Overall, the change in the color in groups with the UV stabilizer (Chimassorb) was less when compared to the groups where the stabilizer was not used. CONCLUSION: The newly developed pigment led to increased color stability as compared to commercially available pigments. Addition of UV stabilizer, Chimassorb led to a further reduction in color change of the pigmented elastomer.

Evaluation of the effect of ultraviolet stabilizers on the change in color of pigmented silicone elastomer: An in vitro study.

AIM AND OBJECTIVE: To compare and evaluate the effect of ultraviolet (UV) stabilizers (Chimassorb 81 and Uvinul 5050) on the color change of pigmented elastomer. MATERIALS AND METHODS: Two pigments - Red (P112 Brilliant Red) and Yellow (P106 Yellow) and two UV stabilizers Chimassorb 81 and Uvinul 5050 were studied. A total of six groups of 10 samples each were fabricated using a combination of the above colors and stabilizers: Group A1 - Red control, Group A2 - Red + Chimassorb 81, Group A3 - Red + Uvinul 5050. Group B1 - Yellow control, Group B2 - Yellow + Chimassorb 81, Group B3 - Yellow + Uvinul 5050. All samples were subjected to ageing in an accelerated weathering chamber (Weather-Ometer). Color values L, a, and b were measured at 500 and 1000 h for all samples before and after weathering and change in color (Delta E) was calculated. RESULTS: All groups showed a significant color change. At 500 h, Chimassorb 81 showed a statistically significant lesser change in both colors (red - 3.66 and yellow - 2.8) compared to their control groups (red - 5.19 and yellow - 4.9). At 1000 h, both UV stabilizers showed lesser color change (A2 - 5.49, B2 - 4.28, A3 - 7.47 and B3 - 4.09) as compared to their respective control groups (A1 - 9.57 and B1 - 5.91). Overall, the change in the color with Group A was more than Group B. CONCLUSION: Addition of UV stabilizers helped the reduction of color change. Chimassorb 81 showed a greater reduction in color change in both colors consistently at 500 and 1000 h.

Human cytomegalovirus-1 and Epstein-Barr virus-1 viral colonization of titanium and zirconia abutments: a split-mouth study.

AIM: Human cytomegalovirus-1 (HCMV-1) and Epstein-Barr virus-1 (EBV-1) detection in submarginal plaque is linked to diseased states of the periodontium. In the present study, we evaluated the viral colonization of titanium and zirconia abutments by HCMV-1 and EBV-1 in a split-mouth study. METHODS: Forty dental implant abutments placed in 20 non-smokers were evaluated retrospectively. Each participant had received at least one each of titanium and zirconia abutments (in function for at least 1 year). HCMV-1 and EBV-1 were evaluated in these clinically-healthy peri-implant sites' submarginal plaque biofilm at one titanium and one zirconia abutment, one healthy tooth site, and serum using polymerase chain reaction assays. Related-samples McNemar test and Wilcoxon signed-rank test were used to determine the differences in viral detection frequency and load, respectively. RESULTS: EBV-1 was detected at the titanium abutment in 60% of participants, but in none at their zirconia abutment (P = 0.04). HCMV-1 was detected at the titanium abutments in 90% of participants, and at the zirconia abutments in 70% of participants. This difference was not significant (P = 0.25). The differences in HCMV-1 viral load between the abutment types were insignificant (P = 0.075). CONCLUSION: EBV-1 did not colonize the biofilm at the zirconia abutments as opposed to the titanium abutments in the same participants. Abutment material could contribute to differences in biofilm characteristics.

Three-Dimensional Evaluation of Alveolar Bone and Soft Tissue Dimensions of Maxillary Central Incisors for Immediate Implant Placement: A Cone-Beam Computed Tomography Assisted Analysis.

INTRODUCTION: This study explored the relationship between the thickness of bone and soft tissue along the labial and palatal aspect of maxillary central incisors. The influence of overall socket width, labiopalatal positioning of the incisor on the bone, and soft tissue thickness were also investigated. MATERIALS AND METHODS: This study used cone-beam computed tomography of 150 patients to determine labial, palatal soft and hard tissue thickness, labiopalatal (B-P) socket width and corelated the same to the labiopalatal positioning of maxillary central incisors. RESULTS: Mean (SD) thicknesses of the labial soft tissue at cervical (C), midroot (M), and apical (A) locations and the corresponding bone thicknesses were 1.07 (0.28), 0.987 (0.27), 1.240 (0.41), and 0.928 (0.39), 0.894 (0.52), 1.57 (0.88), respectively. Similarly, palatal soft tissue and bone thicknesses at locations C, M, A were 1.807 (0.66), 1.557 (0.62), 1.639 (0.66), and 1.679 (0.62), 3.439 (1.28), 6.038 (1.63), respectively. Mean (SD) thicknesses of the B-P socket width at location C was 8.047 (0.963). CONCLUSIONS: There is a positive correlation between the labial and palatal bone and corresponding soft tissue thickness, between thickness of the labial bone and the labiopalatal thickness of the alveolar socket. No correlation was observed between the thickness of the labial cortical bone and the labiopalatal positioning of the tooth.

Access to abutment screw in cement retained restorations: a clinical tip.

Abutment screw loosening has been reported to be the most common prosthetic complications occurring in screw retained as well as cement retained implant restorations. Different methods to treat this issue have been reported in the literature so far; however these have their own short-comings. Retrievability of an implant restoration intact becomes a clinical challenge when the restoration is cement retained especially with an angulated abutment. This technique is aimed at accurately determining the position of the abutment screw in 3 dimensional relationships using a vacuum formed clear stent. This technique can be used as a viable protocol for management of screw loosening in cement retained implant restorations.

Change in color of a maxillofacial prosthetic silicone elastomer, following investment in molds of different materials.

PURPOSE: In the authors' experience, the color of silicone elastomer following polymerization in molds made of gypsum products is slightly different from the color that was matched in the presence of the patient, before the silicone is packed. It is hypothesized that the investing materials and separating media have an effect on the color during the polymerization process of the silicone. MATERIALS AND METHODS: This study compares and evaluates the change in color of silicone elastomer packed in three commonly used investing materials - Dental stone (white color), dental stone (green color), and die stone (orange color); coated with three different separating media - Alginate-based medium, soap solution and a resin-based die hardening material. Pigmented silicone samples of dimensions 1.5 cm × 2 cm × 0.5 cm were made from the elastomer in the above-mentioned mold materials using combinations of the mentioned separating media. These served as test group samples. Control group samples were made by packing a mix of the same pigmented elastomer in stainless steel molds. The L*, a*, b* values of the test and control group samples were determined using a spectrophotometer. The change in color (Delta E) was calculated between the control and test groups. RESULTS: The mean L, a, b values for the control group were, 31.8, 26.2, and 36.3, respectively. Average values of change in color (Delta E) for samples packed utilizing alginate-based medium, die hardener, and soap solution, respectively in white dental stone (2.70, 2.74, and 2.88), green dental stone (2.19, 2.23, 2.42), and orange die stone (3.19, 2.72, 2.80) were tabulated. CONCLUSION: Among the investing materials studied, die stone showed the most color change (3.19), which was statistically significant. Among the separating media, die hardener showed the least color change (2.23). The best combination of an investing material and separating media as per this investigation is a dental stone (green) and alginate-based separating medium.

Fabrication of a custom ocular prosthesis.

Defects of the eye may follow removal of a part of or the entire orbit. This results in the patient becoming visually, esthetically and psychologically handicapped. Restoring the defect with a silicone- or acrylic-based prosthesis not only restores esthetics but also gives back the lost confidence to the patient. This is a case report of a patient with a 'pthisical eye' and details the steps in fabrication of an ocular prosthesis. Particular attention has been given to the laboratory process in this technique to minimize the residual monomer content in the artificial eye.

Comparative analysis of transmittance for different types of commercially available zirconia and lithium disilicate materials.

PURPOSE: Translucency and colour stability are two most important aspects for an aesthetic dental restoration. Glass ceramic restorations are popular amongst clinicians because of their superior aesthetic properties. In the last decade, zirconia has generated tremendous interest due to its favorable mechanical and biological properties. However, zirconia lacks the translucency that lithium disilicate materials possess and therefore has limitations in its use, especially in esthetically demanding situations. There has been a great thrust in research towards developing translucent zirconia materials for dental restorations. The objective of the study was to evaluate and compare the transmittance of a translucent variant of zirconia to lithium disilicate. MATERIALS AND METHODS: Two commercially available zirconia materials (conventional and high translucency) and 2 lithium disilicate materials (conventional and high translucency) with standardized dimensions were fabricated. Transmittance values were measured for all samples followed by a microstructural analysis using a finite element scanning electron microscope. One way analysis of variance combined with a Tukey-post hoc test was used to analyze the data obtained (P=.05). RESULTS: High translucency lithium disilicate showed highest transmittance of all materials studied, followed by conventional lithium disilicate, high translucency zirconia and conventional zirconia. The difference between all groups of materials was statistically significant. The transmittance of the different materials correlated to their microstructure analysis. CONCLUSION: Despite manufacturers' efforts to make zirconia significantly more translucent, the transmittance values of these materials still do not match conventional lithium disilicate. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.