Effects of surface modification techniques on zirconia substrates and their effect on bonding to dual cure resin cement - An in- vitro study.

Aim: This study aims to evaluate the effect of different surface treatments of monolithic zirconia on the bond strength of resin to zirconia and, to explore alternative methods to improve this bonding. Settings and Design: In-Vitro study. Materials and Methods: Fifty rectangular sintered blocks of Yttria-stabilized Tetragonal Zirconia Polycrystal ceramics of dimensions were milled and sintered. These specimens were further divided into five groups (control, air abrasion, etching with primer application, air abrasion with primer application and novel glass infiltrated zirconia surface group), containing 10 samples each. The specimens were analyzed for surface roughness, tensile bond strength to resin cements, and adhesive and cohesive mode of failures. Statistical Analysis Used: ANOVA and Post-Hoc Tukey test was perform to evaluate the significant differences in the mean values of the groups. Results: Air-abraded samples showed the highest surface roughness (4.95 ± 0.65) (P < 0.05). The group with air abrasion followed by primer application showed the highest tensile bond strength (7.12 ± 0.69) (P < 0.05). The lowest surface roughness (0.638 ± 0.8093) and tensile bond strength (2.03 ± 0.58) was seen in samples that were subjected to etchant treatment followed by application of methacryloyloxydecyl di-hydrogen phosphate (MDP) primer. The changes in comparison to the control group were statistically insignificant (P > 0.05). Except Groups A (control) and C (etchant followed by primer), all other groups showed a cohesive failure. Conclusion: Air abrasion of the zirconia surface with 50 µm alumina particles increases the surface roughness without damaging the surface. Air abrasion followed by MDP primer application is the recommended method of surface treatment to achieve superior bonding. Glass infiltration also showed promising results in terms of tensile bond strength.

Anatomic variations of the osteomeatal complex and its relationship to patency of the maxillary ostium: A retrospective evaluation of cone-beam computed tomography and its implications for sinus augmentation.

AIM: The aim of this study is to determine the incidence of obliterated osteomeatal complex (OMC) due to the presence of anatomic variants. SETTINGS AND DESIGN: Retrospective Study. MATERIALS AND METHODS: In this retrospective study, a total of 71 patients, 34 males and 37 females, aged 35-65 years were included in the study. Cone beam computed tomography (CBCT) scans of patients were assessed to identify the status of the OMC in the presence of anatomic variants and their incidence was recorded. The radiological assessment of the anatomical variants was made by viewing the coronal sections of the scans. The variants observed were deviated nasal septum, uncinate process), agger nasi, Haller cells, middle turbinate variants, enlarged bulla, accessory ostium, and maxillary sinus abnormalities). Ostium patency was evaluated in the coronal section of each sinus and classified as "patent" or "obstructed." The most common variants observed were then correlated with the patency of the ostium. STATISTICAL ANALYSIS USED: Chi square test was performed to assess the association between the anatomic variants and the patency of the OMC. RESULTS: In the present study, the incidence of an obliterated OMC due to the presence of anatomic variants was 73.2%. The four most common variants associated with the possibility of an obliterated OMC were the deviated nasal septum (76.2%), middle turbinate (86.4%), enlarged bulla (77.8%), and sinus cavity variants (80.0%). A statistically significant association was noted between middle turbinate variants and Haller cells and the patency of the OMC. CONCLUSION: Thorough pretreatment CBCT evaluation should be performed to assess the presence of anatomic variants and thereby, the patency of the ostium before sinus floor elevation procedures. The pre and postsurgical treatment plans and regimes can be modified according to anticipated postsurgical sequelae, thereby avoiding postsurgical complications and enhancing the success of the graft procedure.

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.