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Optimization of microencapsulation process for self-healing polymeric material

Then S, Gan SN, Noor Hayaty Abu Kasim

Sains Malaysiana, 2011;40:1179-1186.

A series of poly(urea-formaldehyde) (PUF) microcapsules filled with dicyclopentadiene (DCPD) was successfully prepared by in situ polymerization. The effect of diverse process parameters and ingredients on the morphology of the microcapsules was observed by SEM, optical microscopy (OM) and digital microscopy. Different techniques for the characterization of the chemical structure and the core content were considered such as FT-IR and 1H-NMR as well as the characterization of thermal properties by DSC. High yields of free flowing powder of spherical microcapsules were produced. The synthesized microcapsules can be incorporated into another polymeric host material. In the event the host material cracks due to excessive stress or strong impact, the microcapsules would rupture to release the DCPD, which could polymerize to repair the crack.
Fulltext Detail reproduction of elastomeric materials: effect of viscosity and groove geometry

Nik Zarina Nik Mahmood, Noor Hayaty Abu Kasim, Mamat Azuddin, Noor Lide Abu Kassim

Compendium of Oral Science, 2015;2(1):21-31.
MyJurnal

Objective: To evaluate the effect of type of viscosity and groove on surface detail reproduction of elastomeric impression materials. Methods: Two polyvinylsiloxane and polyether elastomeric impression materials were investigated. An aluminium cylindrical reference block with V- and U-shaped grooves of 1 mm and 2 mm in depth was machined using CAD-CAM system. Impressions of the block were taken to produce 35 master dies. Each die was immersed in distilled water for 5 minutes prior to impression making. Surface topography of the dies and impressions were captured using Alicona Imaging System. Mean difference in depth between the mas-ter dies and corresponding impressions’ grooves were analyzed. Results: Type of viscosities and groove showed significant main effects on surface detail (p < .01), but no significant interaction was observed between the two (p > .01). Express™ putty/light exhibited the lowest mean difference in depth for all grooves. The highest mean difference for U1 (38.3μm ± 21.55), U2 (52.96μm ± 30.39),V1 (45.02μm ± 34.82) and V2 (58.44μm ± 44.19) was obtained from Impregum medium, Aquasil medium, Impregum™ heavy/light and Impregum™ heavy/light groups respectively. Conclusion: Express putty/light-bodied material produced the best surface detail, and U-shaped groove showed superior detail reproduction.
Fulltext Impact strength of an experimental polyurethane- based polymer

Zamri Radzi, Noor Hayaty Abu Kasim, Yahya, N.A., Gan, S.N., Daud, N.M., Saffai, L., et al.

Ann Dent, 2007;14(1):46-51.
MyJurnal

The impact strength of a newly developed experimental polyurethane-based polymer which is derived from palm oil (Experimental PU) was compared with denture polymers; heat-cured and self cured polymethyl methacrylate (PMMA) and ® Eclipse , light-activated urethane dimethacrylate prosthetic resin system. Ten specimens were ® prepared using heat-cured PMMA (Meliodent Heat Cure, Heraeus Kulzer, Germany), self cured PMMA ® (Meliodent Rapid Repair, Heraeus Kulzer, ® Germany), Eclipse baseplate resin (Dentsply, USA) and Experimental PU material. Specimens were prepared following manu- facturer’s instructions except for the Experimental PU material where it was prepared in bulk and sectioned to the desired dimension, 64 x 6 x 4 mm. A ‘V’ notch of approximately 0.8mm in depth was machine cut across the 6mm width. Prior to the Charpy type impact test, specimens were soaked in a water bath for 50 hours at 37ºC. ® Eclipse baseplate resin showed the highest 2 impact strength (2.73 kJ/m ±0.54) followed by ® 2 Meliodent Rapid Repair (2.50kJ/m ±0.65), ® 2 Meliodent Heat Cure (1.96kJ/m ±0.42) and 2 Experimental PU (1.04kJ/m ±0.29). One-way ANOVA showed significant interaction between materials (p
Fulltext Alveolar restoration following rapid maxillary expansion with and without corticotomy: A microcomputed tomography study in sheep

Le MHT, Noor Hayaty AK, Zaini ZM, Dom SM, Ibrahim N, Radzi ZB

Korean J Orthod, 2019 Jul;49(4):235-245.
PMID: 31367578 DOI: 10.4041/kjod.2019.49.4.235

Objective: This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods.
Methods: Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test.
Results: The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control.
Conclusions: Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.
Fulltext Adjunctive buccal and palatal corticotomy for adult maxillary expansion in an animal model

Le MHT, Lau SF, Ibrahim N, Noor Hayaty AK, Radzi ZB

Korean J Orthod, 2018 Mar;48(2):98-106.
PMID: 29564219 DOI: 10.4041/kjod.2018.48.2.98

Objective: This study aimed to explore the usefulness of adjunctive buccal and palatal corticotomy for adult maxillary expansion in an animal model using cone-beam computed tomography (CBCT).
Methods: Twelve adult sheep were randomly divided into two groups (each n = 6): a control group, where no treatment was administered, and a treatment group, where buccal and palatal corticotomy-assisted maxillary expansion was performed. CBCT scans were taken before (T1) and after (T2) treatment. Differences in all transverse dental and alveolar dimensions, alveolar width at crest level, hard palate level, horizontal bone loss, interdental cusp width and inter-root apex were assessed using Wilcoxon signed-rank and Mann-WhitneyU-tests. Kruskal-Wallis tests and pairwise comparisons were used to detect the significance of differences among the inter-premolar and inter-molar widths.
Results: CBCT data revealed significant changes in all transverse dental and alveolar dimensions. The mean interpremolar alveolar width showed an increase of 2.29 to 3.62 mm at the hard palate level, 3.89 to 4.38 mm at the alveolar crest level, and 9.17 to 10.42 mm at the buccal cusp level. Dental changes in the vertical dimension were not significant.
Conclusions: Our findings based on an adult animal model suggest that adjunctive buccal and palatal corticotomy can allow for both skeletal and dental expansion, with the amount of dental expansion exceeding that of skeletal expansion at alveolar crest and hard palate levels by two and three folds, respectively. Therefore, this treatment modality is potential to enhance the outcomes of maxillary expansion in adults.