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Wear of materials used in dentistry: a review of the literature

Sulong MZ, Aziz RA

J Prosthet Dent, 1990 Mar;63(3):342-9.
PMID: 2407832

This is a review of the literature concerning wear related to the following materials used in dentistry: dental amalgam, composite resins, and glass-ionomer cements, as well as natural tooth substance. Discussions are included on both in vivo and in vitro studies in which various methods were used to help determine wear resistance.

Matched MeSH terms: Composite Resins*
Water sorption characteristics of restorative dental composites immersed in acidic drinks

Rahim TN, Mohamad D, Md Akil H, Ab Rahman I

Dent Mater, 2012 Jun;28(6):e63-70.
PMID: 22480722 DOI: 10.1016/j.dental.2012.03.011

To determine the diffusion coefficient, water sorption and solubility of various types of restorative dental composites and to evaluate the effect of acidic media (orange juice and coke) on their characteristics.

Matched MeSH terms: Composite Resins/chemistry*
Water activity effect on lipase immobilized onto different compositions of poly(HEMA-MMA)

Esa NM, Yunus WM, Ahmad MB, Basri M, Razak CN, Salleh AB

Ann N Y Acad Sci, 1998 Dec 13;864:489-92.
PMID: 9928130
Matched MeSH terms: Composite Resins
Variasi profil 210Po dan 210Pb dalam teras sedimen di pesisir pantai perairan Sarawak

Zal Uâ€™yun Wan Mahmood, Che Abd Rahim Mohamed, Zaharudin Ahmad, Abdul Kadir Ishak

Sains Malaysiana, 2008;37.

Kajian ini dijalankan untuk melihat variasi taburan 210Po dan 210Pb melalui profil menegak aktivitinya, serta nisbah aktiviti 210Po/210Pb di dalam teras sedimen yang diambil di beberapa stesen persampelan pesisir pantai perairan Sarawak. Didapati profil taburan radionuklid tersebut dalam teras sedimen adalah berubah-ubah mengikut lokasi persampelan dan telah dibuktikan melalui analisis ANOVA yang menunjukkan bahawa terdapat perbezaan bererti pada 95% aras keyakinan bagi aktiviti 210Po (p = 0.000), 210Pb (p = 0.035) dan 210Po/210Pb (p = 0.000) di semua lokasi kajian. Secara umumnya, aktiviti 210Po dan 210Pb yang diukur masing-masing dalam julat 337 ke 2460 Bq/kg, 11 ke 84 Bq/kg di SR 01; 224 ke 2008 Bq/kg, 6 ke 80 Bq/kg di SR 02; 119 ke 1595 Bq/kg, 6 ke 84 Bq/kg di SR 03; 241 ke 2294 Bq/kg, 5 ke 82 Bq/kg di SR 04 dan 175 ke 1340 Bq/kg, 4 ke 44 Bq/kg di SR 05. Merujuk kepada julat tersebut, didapati aktiviti 210Po adalah lebih tinggi daripada aktiviti 210Pb dengan purata nisbah 210Po/210Pb di semua stesen adalah melebihi satu, iaitu dalam julat 20 ke 35. Variasi profil taburan radionuklid tersebut dipercayai dipengaruhi oleh beberapa faktor sekitaran dan telah dibuktikan terdapat korelasi yang kuat di antara taburan radionuklid dengan komposisi sedimen jenis kelodak (210Po:r = 0.701 dan 210Pb: r = 0.648), kedalaman air (210Po: r = -0.647) dan jarak stesen dari daratan (210Po: r = 0.746 dan 210Pb: r = 0.975). Oleh itu, dapat disimpulkan bahawa faktor-faktor tersebut merupakan penyumbang utama ke atas perubahan yang berlaku kepada taburan 210Po dan 210Pb.

Matched MeSH terms: Composite Resins
Fulltext Unsupervised bivariate data clustering for damage assessment of carbon fiber composite laminates

May Z, Alam MK, Mahmud MS, Rahman NAA

PLoS One, 2020;15(11):e0242022.
PMID: 33186372 DOI: 10.1371/journal.pone.0242022

Damage assessment is a key element in structural health monitoring of various industrial applications to understand well and predict the response of the material. The big uncertainty in carbon fiber composite materials response is because of variability in the initiation and propagation of damage. Developing advanced tools to design with composite materials, methods for characterizing several damage modes during operation are required. While there is a significant amount of work on the analysis of acoustic emission (AE) from different composite materials and many loading cases, this research focuses on applying an unsupervised clustering method for separating AE data into several groups with distinct evolution. In this paper, we develop an adaptive sampling and unsupervised bivariate data clustering techniques to characterize the several damage initiations of a composite structure in different lay-ups. An adaptive sampling technique pre-processes the AE features and eliminates redundant AE data samples. The reduction of unnecessary AE data depends on the requirements of the proposed bivariate data clustering technique. The bivariate data clustering technique groups the AE data (dependent variable) with respect to the mechanical data (independent variable) to assess the damage of the composite structure. Tensile experiments on carbon fiber reinforced composite laminates (CFRP) in different orientations are carried out to collect mechanical and AE data and demonstrate the damage modes. Based on the mechanical stress-strain data, the results show the dominant damage regions in different lay-ups of specimens and the definition of the different states of damage. In addition, the states of the damage are observed using Scanning Electron Microscope (SEM) analysis. Based on the AE data, the results show that the strong linear correlation between AE and mechanical energy, and the classification of various modes of damage in all lay-ups of specimens forming clusters of AE energy with respect to the mechanical energy. Furthermore, the validation of the cluster-based characterization and improvement of the sensitivity of the damage modes classification are observed by the combined knowledge of AE and mechanical energy and time-frequency spectrum analysis.

Matched MeSH terms: Composite Resins/chemistry*
Fulltext The role of silica-containing agro-industrial waste as reinforcement on physicochemical and thermal properties of polymer composites

Rizal S, Fizree HM, Hossain MS, Ikramullah, Gopakumar DA, Wan Ni EC, et al.

Heliyon, 2020 Mar;6(3):e03550.
PMID: 32190763 DOI: 10.1016/j.heliyon.2020.e03550

This study was conducted to determine the influence of the oil palm boiler ash (OPBA) reinforcement on the microstructural, physical, mechanical and thermal properties of epoxy polymer composites. The chemical composition analysis of OPBA revealed that it contains about 55 wt.% of SiO2 along with other metallic oxides and elements. The surface morphology of OPBA showed angular and irregular shapes with porous structures. The influence of OPBA as a reinforcement in epoxy composite was studied with varying filler loadings (10-50 wt.%) and different particle sizes (50-150 μm). The result showed that the incorporation of OPBA in composites has improved the physical, mechanical and thermal properties of the epoxy matrix. The highest physical and mechanical properties of fabricated composites were attained with 30 wt.% loading and size of 50 μm. Also, thermal stability and the percentage of char residue of the composite increased with increasing filler loading. Furthermore, the contact angle of OPBA reinforced epoxy composites increased with the increase of filler loading. The lowest value of the contact angle was obtained at 30 wt.% of filler loading with the OPBA particle size of 50 μm. The finding of this study reveals that the OPBA has the potential to be used as reinforcement or filler as well as an alternative of silica-based inorganic fillers used in the enhancement of mechanical, physical and thermal properties of the epoxy polymer composite.

Matched MeSH terms: Composite Resins
Fulltext The load capacity of maxillary central incisor with simulated flared root canal restored with different fiber-reinforced composite post and cementation protocols

Beh YH, Halim MS, Ariffin Z

PeerJ, 2023;11:e16469.
PMID: 38025677 DOI: 10.7717/peerj.16469

BACKGROUND: This study aimed to evaluate the load capacity of maxillary central incisors with simulated flared root canal restored with different fiber-reinforced composite (FRC) post cemented with either self-adhesive or self-etch resin cement and its mode of fracture.
METHODS: Sixty-five extracted maxillary incisors were decoronated, its canal was artificially flared and randomly categorized into group tFRC (tapered FRC post) (n = 22), mFRC (multi-FRC post) (n = 21), and DIS-FRC (direct individually shaped-FRC (DIS-FRC) post) (n = 22), which were further subdivided based on cementation resin. The posts were cemented and a standardized resin core was constructed. After thermocycling, the samples were loaded statically and the maximum load was recorded.
RESULTS: The load capacity of the maxillary central incisor was influenced by the different FRC post system and not the resin cement (p = 0.289), and no significant interaction was found between them. Group mFRC (522.9N) yielded a significantly higher load capacity compared to DIS-FRC (421.1N). Overall, a 55% favorable fracture pattern was observed, and this was not statistically significant.
CONCLUSION: Within the limitation of the study, it can be concluded that prefabricated FRC posts outperform DIS-FRC posts in terms of the load capacity of a maxillary central incisor with a simulated flared root canal. The cementation methods whether a self-adhesive or self-etch resin cement, was not demonstrated to influence the load capacity of a maxillary central incisor with a flared root canal. There were no significant differences between the favorable and non-favorable fracture when FRC post systems were used to restored a maxillary central incisor with a flared root canal.

Matched MeSH terms: Composite Resins/therapeutic use
The influence of experimental silane primers on dentin bond strength and morphology: a laboratory and finite element analysis study

Mustafa AA, Matinlinna JP, Saidin S, Kadir MR

J Prosthet Dent, 2014 Dec;112(6):1498-506.
PMID: 24993375 DOI: 10.1016/j.prosdent.2014.05.011

STATEMENT OF PROBLEM: The inconsistency of dentin bonding affects retention and microleakage.
PURPOSE: The purpose of this laboratory and finite element analysis study was to investigate the effects on the formation of a hybrid layer of an experimental silane coupling agent containing primer solutions composed of different percentages of hydroxyethyl methacrylate.
MATERIAL AND METHODS: A total of 125 sound human premolars were restored in vitro. Simple class I cavities were formed on each tooth, followed by the application of different compositions of experimental silane primers (0%, 5%, 25%, and 50% of hydroxyethyl methacrylate), bonding agents, and dental composite resins. Bond strength tests and scanning electron microscopy analyses were performed. The laboratory experimental results were validated with finite element analysis to determine the pattern of stress distribution. Simulations were conducted by placing the restorative composite resin in a premolar tooth by imitating simple class I cavities. The laboratory and finite element analysis data were significantly different from each other, as determined by 1-way ANOVA. A post hoc analysis was conducted on the bond strength data to further clarify the effects of silane primers.
RESULTS: The strongest bond of hybrid layer (16.96 MPa) was found in the primer with 25% hydroxyethyl methacrylate, suggesting a barely visible hybrid layer barrier. The control specimens without the application of the primer and the primer specimens with no hydroxyethyl methacrylate exhibited the lowest strength values (8.30 MPa and 11.78 MPa) with intermittent and low visibility of the hybrid layer. These results were supported by finite element analysis that suggested an evenly distributed stress on the model with 25% hydroxyethyl methacrylate.
CONCLUSIONS: Different compositions of experimental silane primers affected the formation of the hybrid layer and its resulting bond strength.

Matched MeSH terms: Composite Resins/chemistry
Fulltext The flexural strengths of five commercially available tooth-coloured restorative materials

Sulaiman, E., Yeo, Y.M., Chong, Y.T.

Ann Dent, 2007;14(1):39-45.
MyJurnal

Purpose of the study: The objective of this study was to investigate the flexural strengths of five commercially available tooth-coloured restorative materials – Alpha-Dent (composite resin, Dental Technologies Inc.), Solare Anterior (composite resin, GC), F2000 (polyacid-modified composite resin, 3M), Beautifil (giomer, Shofu) and Fuji II LC (resin- modified glass ionomer cement, GC] using the ISO 4049 specifications. Materials and Method: Ten specimens of (25±0.2)mm x (2±0.1)mm x (2±0.1)mm from each material were prepared at 22-23ºC using a customized metal mould. After light polymerization, the specimens were stored in distilled water at 37ºC for 24 hours. The specimens were subsequently blotted dry, measured and subjected to flexural testing using an Instron Universal Testing Machine with a crosshead speed of 0.5mm/min. The flexural strengths were calculated from the maximum load exerted on the specimens. Data were analysed using one way ANOVA and scheffe’s post-hoc multiple comparison tests at a significance level of 0.05.Results: The results showed that the mean flexural strengths of Beautifil, Solare Anterior and Alpha-Dent were above 80 MPa and those of F2000 and Fuji II LC were below 80 MPa. The results of one-way ANOVA and Scheffe’s post-host tests demonstrated that Beautifil had significantly higher mean flexural strength compared to Fuji II LC, F2000 and Alpha-Dent (P

Matched MeSH terms: Composite Resins
The effect of filler content and processing variables on dimensional accuracy of experimental composite inlay material

Razak AA, Harrison A

J Prosthet Dent, 1997 Apr;77(4):353-8.
PMID: 9104710

Dimensional accuracy of a composite inlay restoration is important to ensure an accurate fit and to minimize cementation stresses.

Matched MeSH terms: Composite Resins/analysis; Composite Resins/chemistry*
The effect of chewing simulation on surface roughness of resin composite when opposed by zirconia ceramic and lithium disilicate ceramic

Ho TK, Satterthwaite JD, Silikas N

Dent Mater, 2018 02;34(2):e15-e24.
PMID: 29175160 DOI: 10.1016/j.dental.2017.11.014

OBJECTIVE: To assess the change in surface roughness of nanohybrid resin composite (Tetric EvoCeram) after antagonist wear against monolithic zirconia and lithium disilicate ceramics through a simulated chewing test using a three-dimensional (3D) profilometer.
METHODS: A total of 40 Tetric EvoCeram™ resin composite specimens against either a Lava™ Plus zirconia antagonist (n=20) or IPS e.max Press lithium disilicate antagonist (n=20) were prepared for the study. The surface roughness profiles of each resin composite before and after an in-vitro simulated chewing test were analysed using a 3D profilometer and Talymap software. After the simulated chewing, the surface profiles of representative Tetric EvoCeram specimens from each group were analysed using scanning electron microscopy. Independent t-test and paired t-test were used for statistical analysis.
RESULTS: For both lithium disilicate and zirconia groups, all surface roughness parameters (Ra, Rt, Sa, Sq,) of Tetric EvoCeram were significantly higher post-chewing compared to pre-chewing (p<0.05); the post-chewing surface roughness parameters of Tetric EvoCeram for the lithium disilicate group were significantly higher (p<0.05) than in the zirconia group.
SIGNIFICANCE: This chewing simulation test showed that Tetric EvoCeram composites exhibited a rougher surface when opposing lithium disilicate ceramic compared to opposing zirconia ceramic.

Matched MeSH terms: Composite Resins/chemistry*
Fulltext The effect of bur preparation on the surface roughness and reline bond strength of urethane dimethacrylate denture base resin

Baig MR, Ariff FT, Yunus N

Indian J Dent Res, 2011 Mar-Apr;22(2):210-2.
PMID: 21891887 DOI: 10.4103/0970-9290.84288

BACKGROUND: The clinical success of relining depends on the ability of reline resin to bond to denture base. Surface preparations may influence reline bond strength of urethane-based dimethacrylate denture base resin.
AIM: To investigate the effect of bur preparation on the surface roughness (R a ) of eclipse denture base resin and its shear bond strength (SBS) to an intra-oral self-curing reline material. The mode of reline bonding failure was also examined.
MATERIALS AND METHODS: Twenty-four cylindrical Eclipse™ specimens were prepared and separated into three groups of eight specimens each. Two groups were subjected to mechanical preparation using standard and fine tungsten carbide (TC) burs and the third group (control) was left unprepared. The R a of all specimens was measured using a contact stylus profilometer. Subsequently, relining was done on the prepared surface and SBS testing was carried out a day later using a universal testing machine.
RESULTS: One-way ANOVA revealed significant differences (P<0.05) in R a and SBS values for all the groups. Post-hoc Tukey's HSD test showed significant differences (P<0.05) between all the groups in the R a values. For SBS also there were significant differences (P<0.05), except between standard bur and control.
CONCLUSIONS: 1) There was a statistically significant difference in the R a of Eclipse™ specimens prepared using different carbide burs (P<0.05). 2) There was a statistically significant difference in the relined SBS (P<0.05) when prepared using different burs, but the difference between the standard bur and the control group was not statistically significant.

Matched MeSH terms: Composite Resins/chemistry
The combined effect of dental post and cement materials on fracture resistance and fracture mode of endodontically-treated teeth

Mohamed Abdulmunem, Hadijah Binti Abdullah, Noor Hayaty Binti Abu Kasim, Ali Dabbagh

Sains Malaysiana, 2015;44:1189-1194.

The aim of this study was to investigate the simultaneous influence of various dental posts and cementation materials on the fracture resistance and failure mode of the endodontically-treated teeth. Sixty endodontically treated upper central incisors were randomly divided into two main groups, each consisted of three subgroups restored with titanium, fiber and stainless steel posts. The posts in the first and second groups were luted with zinc phosphate and composite resin cements, respectively. Composite cores were built-up over the specimens and then retained with nickel-chromium crowns. Specimens were thermocycled and then loaded at 135o until failures were observed. The obtained data of fracture resistances and failure modes were analyzed using Two-way ANOVA and the Chi-Square tests, respectively. The results showed that the zinc phosphate cement resulted in relatively higher fracture resistances. However, luting of dental posts with composite resin provided more restorable failures in endodontically-treated teeth. Moreover, the teeth restored by fiber posts exhibited desirable fracture resistances with more restorable failure modes, compared with those restored by titanium or stainless steel posts.

Matched MeSH terms: Composite Resins
Teknik Seismos Pantulan dan Geoelektrik Dwikutub-dwikutub dalam Pengesanan Lohong Batu Kapur di Batu Caves (Seismic Reflection and dipole-dipole Geoelectrical Techniques in Detecting Cavity in the Limestone Area of Batu Caves)

Umar Hamzah, Abd. Rahim Samsudin

Sains Malaysiana, 1997;26.

Identification of a possible source of engineering geological hazard in the limestone area such as cavities, sinkholes and an underground cavern have become necessity for site investigation before any construction of roads, bridges and buildings are carried out. The study is also necessary for tunneling and underground mining works where knowledge of the engineering properties of the rock mass is very important in order to assess the suitability and safety of a proposed building. Geophysical techniques have been widely used in engineering geological study to deal with such problems that normally arise at construction sites with limestone bedrock. In this study, shallow seismic reflection technique and dipole-dipole geoelectrical methods were used to detect the presence of cavity in lime stone area of Batu Cave, Kuala Lumpur. The exact location and depth of cavities in the area were determined from the existing borehole data and report provided by the Geological Survey Department of Malaysia. Based on the borehole data, several cavities that were filled-up with water and fine silt are encountered at depths of 15.7m to 17.8m, 20.2m to 21.1m and 21.4m to 25.7m. Three shallow seismic reflection profiles were established on the cavity area and the results show that the cavities in the limestone occur in the form of 20 to 30m long subterranean channel of 15 to 30 m depth. Dipole-dipole resistivity survey conducted on seismic lines one and three also indicates the presence of the channel and cavities in the limestone.
Pengecaman punca bencana geologi kejuruteraan di kawasan batu kapur seperti lohong batu kapur, kewujudan lubang benam dan gua-gua batu kapur telah menjadi amat penting dalam penyiasatan tapak sebelum sesuatu pembinaan seperti jalan raya, jambatan dan bangunan dilakukan. Begitu juga dalam kerja-kerja penerowongan dan perlombongan, pengetahuan asas sifat kejuruteraan jasad batuan amat perlu diketahui untuk menitai kesesuaian dan keselamatan bangunan yang bakal dibina. Teknik geofizik telah digunakan secara meluas dalam kajian geologi kejuruteraan untuk menangani masalah yang terdapat di tapak-tapak binaan yang mempunyai batu kapur sebagai batuan dasar. Dalam kajian ini teknik seismos pantulan cetek dan kaedah geoelektrik dwikutub-dwikutub telah digunakan untuk mengesan rongga batu kapur yang terdapat di kawasan Batu Caves, Kuala Lumpur. Kedudukan dan kedalaman rongga batu kapur di kawasan kajian telah ditentukan melalui data lubang gerudi dan laporan yang diperoleh daripada Jabatan Kajibumi Malaysia. Berdasarkan data lubang gerudi tersebut terdapat beberapa rongga yang terisi air dan pasir halus berlodak di kedalaman 15.7 m hingga 17.8 m, 20.2 m hingga 21.1 m dan 21.4 m hingga 25.7 m. Tiga profil seismos pantulan cetek telah dibuat di kawasan berongga tersebut dan hasil survei menunjukkan rongga dalam batu kapur tersebut membentuk palung sepanjang hampir 20 - 30 m pada kedalaman antara 15 m hingga 30 m. Rentisan survei geoelektrik dwikutub yang dilakukan pada profil seismos satu dan tiga juga memperlihatkan kehadiran lohong dan palung dalam batu kapur tersebut.

Matched MeSH terms: Composite Resins
Fulltext Technique to repair iatrogenically-damaged roots during post canal preparation using resin composite and optic fibre posts

Lui, J.L.

Ann Dent, 2007;14(1):14-18.
MyJurnal

During post crown restoration, the preparation of the post canal can be fraught with difficulties resulting in widening, gouging and transportation of the post canal; sometimes with near root perforation. A technique is described to repair such iatrogenically damaged internal root canal walls using reinforcing resin composite and optic glass fibre posts. The root dentine, resin composite and glass fibres, having similar moduli of elasticity, will result in a repaired root with a ‘monolithic’ structure and possessing numerous desirable characteristics. This repair technique can easily be carried out in one sitting at the chairside thereby allowing the continued serviceability of the iatrogenically compromised root-filled tooth.

Matched MeSH terms: Composite Resins
Fulltext Systems perspectives in agricultural education, research and development: A vision for sustaining food security in Asia

C. Devendra

ASM Science Journal, 2013;7(2):152-165.
MyJurnal

Systems perspectives are fundamental in driving technological improvements and yield-enhancing strategies that improve agricultural productivity. These can resolve farmerʼs problems and are important pathways for sustaining food and nutritional security for human welfare in Asia. The essential determinants of this objective are the capacity to efficiently manage the natural resource base (land, crops, animals, and water) to resolve constraints to farming systems, and notably the integration of multiple research and development (R&D) issues through all levels of formal and non-formal learning systems. Both formal and informal education systems are important, with the former relating more to universities and colleges, and the latter to the intermediate level. Graduates from this level have the primary responsibility of introducing improved technologies and change to farmers, mainly along production and disciplinary pathways.The traditional research–extension–farmer model for technology delivery is no longer acceptable, due to “top down” extension functions and prescriptions, ineffectiveness to cope with the dynamics of production systems, complex interactions within the natural resources, effects of climate change and globalisation. There are also reservations on the technical capacity and skills of extension agents, constraints identification, methods for technology diffusion and dissemination, and innovative use of beneficial technological improvements that can directly respond to the needs of small farmers, and impact on subsistence agriculture. Agricultural education and systems perspectives are therefore an overriding compelling necessity which transcends prevailing limitations to waning agriculture and rural growth. Their wider recognition and applications provides an important means to maximise efficiency in the potential use; of the natural resources, increase engagement and investments in agriculture, promote ways to become more self-reliant in the development of crucial new technologies and intensification. These together can meet the challenges of the future and overcome the legacy of continuing poverty, food and nutritional insecurity. Asian farming systems, with their diversity of crops and animals, traditional methods, multiple crop-animal interactions, numerous problems of farmers present increasingly complex issues of natural resource management (NRM) and the environment. Many if not all of these can only be resolved by interdisciplinary R&D, which overcomes a major weakness of many R&D programmes presently and in the past. Improved education and training is a powerful and important driver of community-based participation aimed at enhancing sustainable food security, poverty reduction and social equity in which the empowerment of women in activities that support organising themselves is also an important pathway to enhance self-reliance and their contribution to agriculture. A vision for the future in which improved agricultural education in a systems context can provide the pathway to directly benefit the revitalisation of agriculture and agricultural development is proposed with a three-pronged strategy as follows:
Define policy for the development of appropriate curricular for formal agricultural education that provides strong multi-disciplinary orientation and improved understanding of the natural resources (land, crops, animals and water) and their interactions
Organise formal degree education and specialisation at the university level that reflects strong training in understanding of agricultural systems; systems perspectives, methodologies and their application, and
Define non-formal education and training needs that can be intensified at different levels, including the trainin of trainers as agents of change.

Matched MeSH terms: Composite Resins
Fulltext Susceptibility of selected tooth-coloured dental materials to damage by common erosive acids

Wan Bakar W, McIntyre J

Aust Dent J, 2008 Sep;53(3):226-34.
PMID: 18782366 DOI: 10.1111/j.1834-7819.2008.00053.x

Erosive substances such as gastric acids, lemon juice and even the less erosive cola drinks have been extensively investigated for their destructive effects on enamel. However, their effects on the tooth-coloured restoratives has not been widely analysed. The objective of this study was to assess their effects on the more commonly used glass containing restorative materials in vitro.

Matched MeSH terms: Composite Resins*
Survei keberintangan geoelektrik untuk mengesan terowong di Bukit Tenggek, Setiu, Terengganu

Siti Nazira Masrom, Mohd Hariri Arifin, Abd Rahim Harun, Abdul Rahim Samsudin

Sains Malaysiana, 2011;40:1223-1229.

Survei keberintangan geoelektrik ini telah dijalankan di kawasan Bukit Tenggek, Setiu, Terengganu untuk mengesan kemungkinan wujudnya terowong lama yang dipercayai berada di kawasan berkenaan. Kaedah keberintangan geoelektrik ini bukanlah asing dan didapati amat berkesan di dalam eksplorasi mencari bahan arkeologi dan struktur terkambus di bawah tanah (terowong dan bahan artifak). Survei keberintangan geoelektrik ini dijalankan dengan menggunakan peralatan ABEM Terrameter SAS1000 dan susun atur elektrod jenis Wenner. Kawasan kajian terletak di kawasan lembah yang lembap dan terdapat anak sungai yang merentasi kawasan tersebut. Imej keberintangan 2-D menunjukkan wujudnya beberapa kawasan beranomali yang boleh dikaitkan dengan struktur yang dicari. Nilai keberintangan yang rendah mewakili kawasan yang dianggarkan wujudnya terowong lama. Manakala anomali yang menunjukkan bentuk gugusan dianggarkan berasosiasi dengan lokasi tong/bahan artifak. Profil keberintangan 3-D menunjukkan anomali yang mungkin disebabkan oleh wujudnya satu terowong mendatar dan dua terowong menegak. Namun, kerja galicari perlu dilakukan bagi menentukan punca sebenar anomali tersebut.

Matched MeSH terms: Composite Resins
Fulltext Surface roughness of tooth coloured restorative materials

Mohd Shahminan Ibrahim, Wen, Yap Kai, Gonzalez, Maria Angela Garcia, Noor Azlin Yahya

Ann Dent, 2020;27(1):41-49.
MyJurnal

This study compared the surface roughness of selected tooth coloured restorative materials that were polished according to manufacturers’ instructions and Sof-Lex. It also assessed the surface roughness of polished materials after thermocycling.Filtek Z350XT, Beautifil-Bulk Restorative and Cention N, were used in this study. A stainless steel mould (10mm diameter x 2mm height) was used to fabricate 75 cylindrical specimens: 15 Filtek Z350XT (FZ), 30 Beautifil-Bulk Restorative (BB) and 30 Cention N (CN). All 15 FZ specimens were polished with Sof-Lex. Fifteen BB and CN specimens were polished according to manufacturers’ instructions. The remaining fifteen BB and CN specimens were polished using Sof-Lex. All the specimens were subjected to thermocycling (1000 cycles). Surface roughness was assessed quantitatively with profilometry after specimen preparation (Mylar stage), polishingand thermocycling. Data were analysed using SPSS version 25.0 at α=0.05. When polished according to manufacturers’ instructions, BB had the lowest mean surface roughness (Ra) values (0.13±0.01μm) followed sequentially by CN (0.14±0.03μm) and FZ (0.15±0.02μm). The differences were not statistically significant. When polished with Sof-Lex, BB exhibited the smoothest surface (0.116±0.03μm) followed sequentially by and FZ (0.150±0.02μm) and CN (0.157±0.02μm). Thermocycling caused an increase in the Ra. The differences were statistically significant. All materials tested had Ra values below the threshold value of 0.2 μm at Mylar stage and after polishing with their recommended polishing system and Sof-Lex. Thermocycling produced rougher surfaces that did not exceed the threshold Ra value. Polishability was material dependent.

Matched MeSH terms: Composite Resins
Studies on the effects of titanate and silane coupling agents on the performance of poly (methyl methacrylate)/barium titanate denture base nanocomposites

Elshereksi NW, Ghazali MJ, Muchtar A, Azhari CH

J Dent, 2017 Jan;56:121-132.
PMID: 27916635 DOI: 10.1016/j.jdent.2016.11.012

OBJECTIVES: This study aimed to fabricate and characterise silanated and titanated nanobarium titanate (NBT) filled poly(methyl methacrylate) (PMMA) denture base composites and to evaluate the behaviour of a titanate coupling agent (TCA) as an alternative coupling agent to silane. The effect of filler surface modification on fracture toughness was also studied.
METHODS: Silanated, titanated and pure NBT at 5% were incorporated in PMMA matrix. Neat PMMA matrix served as a control. NBT was sonicated in MMA prior to mixing with the PMMA. Curing was carried out using a water bath at 75°C for 1.5h and then at 100°C for 30min. NBT was characterised via Fourier transform-infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis before and after surface modification. The porosity and fracture toughness of the PMMA nanocomposites (n=6, for each formulation and test) were also evaluated.
RESULTS: NBT was successfully functionalised by the coupling agents. The TCA exhibited the lowest percentage of porosity (0.09%), whereas silane revealed 0.53% porosity. Statistically significant differences in fracture toughness were observed among the fracture toughness values of the tested samples (p<0.05). While the fracture toughness of untreated samples was reduced by 8%, an enhancement of 25% was achieved after titanation. In addition, the fracture toughness of the titanated samples was higher than the silanated ones by 10%.
CONCLUSION: Formation of a monolayer on the surface of TCA enhanced the NBT dispersion, however agglomeration of silanated NBT was observed due to insufficient coverage of NBT surface. Such behaviour led to reducing the porosity level and improving fracture toughness of titanated NBT/PMMA composites. Thus, TCA seemed to be more effective than silane.
CLINICAL SIGNIFICANCE: Minimising the porosity level could have the potential to reduce fungus growth on denture base resin to be hygienically accepTable Such enhancements obtained with Ti-NBT could lead to promotion of the composites' longevity.

Matched MeSH terms: Composite Resins/chemistry

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