Pemanfaatan Bahan Alam Anchor sebagai Bahan Konservasi Fosil di Sangiran

Balai Pelestarian Situs Manusia Purba Sangiran telah menggunakan bahan alam anchor sebagai bahan perekat untuk menyambungkan fosil yang patah sejak tahun 2018 setelah melakukan penelitian selama dua tahun yaitu pada tahun 2016 dan pada tahun 2017. Seiring berjalannya waktu penggunaan bahan alam anchor mengalami kerusakan seperti hasil sambungan patah atau retak yang diakibatkan penyimpanan fosil yang kurang tepat. Penelitian ini bertujuan untuk menentukan kekuatan mekanik campuran fosil dan anchor. Penelitian menggunakan rancangan acak lengkap satu faktor dengan variasi perbandingan fosil ukuran 100mesh dan anchor (1:1, 2:1, dan 3:1) dengan dua ulangan. Kemudian melakukan pengujian kuat tekan menggunakan universal testing machine berdasarkan standar ASTM D695-96. Hasilnya menunjukkan nilai kuat tekan tertinggi campuran serbuk fosil dan anchor dengan pada perbandingan 1:1 yaitu 19,996 N/mm2 dan nilai kuat tekan terendah pada perbandingan serbuk fosil dan anchor 3:1 yaitu 12,51 N/mm2. Lem anchor hasil penelitian telah memenuhi persyaratan SNI 06-6049-1999 tentang polivinil asetat emulsi untuk pengerjaan kayu sebagai standar pembanding yaitu memiliki kekuatan rekat minimal 3 N/mm2 dan memiliki pH (3-8).

Identifikasi material dan perhitungan kembali tegangan tangensial barrel rear suspension dump truck EH 5000

Suspensi dump truck berfungsi sebagai peredam kejutan dari permukaan jalan, penyangga berat unit, memberikan kenyamanan pada operator dan menjaga kestabilan unit (empat roda selalu menyentuh tanah). Barrel adalah komponen penting dalam suspensi dump truck. Komponen tersebut berbentuk tabung pada suspensi dan berfungsi sebagai rumah untuk piston. Barrel yang bukan standar original Hitachi sering mengalami kerusakan. Penelitian ini bertujuan untuk mengetahui nilai kekerasan dan kekuatan tarik pada material barrel suspensi belakang, komposisi kimia dan struktur mikro pada material barrel suspensi belakang, dan nilai tegangan tangensial pada dinding barrel.Penelitian ini dilakukan dengan empat pengujian, yaitu uji kekerasan, uji tarik, uji struktur mikro dan uji komposisi kimia. Pengujian kekerasan dengan menggunakan alat uji kekerasan Brinell, pengujian tarik dengan menggunakan alat uji tarik (universal testing machine), pengujian komposisi kimia dengan alat spectrometer, dan pengujian struktur mikro dengan metallographic microscope. Sedangkam untuk mencari nilai tegangan pada dinding barrel dilakukan perhitungan tegangan tangensial.Hasil dari penelitian ini menunjukkan bahwa material barrel mempunyai nilai kekerasan rata rata 200,50 HB, nilai kekuatan luluh σy 433-494 MPa, nilai kekuatan tarik σu 740-751 MPa, kandungan pada material termasuk kategori baja 27 SiMn, struktur mikro pada material terdapat fasa ferrite dan pearlite, material aman terhadap beban statis, dan tegangan tangensial yang terjadi lebih rendah dari kekutan luluh.

Retention of Cast Posts Cemented with Two Commonly Used Conventional and Two Resin Cements and the Mode of Root Fracture Following Their Removal

Objectives: This study aimed to compare the retention of cast posts cemented with four types of cements and assess the mode of root fracture following their removal. Materials and Methods: In this in vitro, experimental study, 48 upper central incisors were randomly divided into 4 groups of 12, and were endodontically treated. The fabricated cast posts in each group were cemented with zinc phosphate (Masterdent), glass ionomer (GI; Meron), Meta resin cement, and Panavia SA resin cement. A device was customized for post removal by a universal testing machine similar to WAM X pliers. The retention of cemented posts was measured by the pull-out test in a universal testing machine. Next, the teeth were macroscopically and microscopically inspected regarding the occurrence and sites of catastrophic fracture, cracks, or craze lines. Quantitative and qualitative data were analyzed by ANOVA, and Chi-square test, respectively (P<0.05). Results: ANOVA showed a significant difference in the mean retention of cements (P<0.001). Panavia provided the highest retention (278.6±34.9 N) followed by zinc phosphate (221.9±28.88 N), GI (161.3±60.7 N), and Meta (140.4±66.54 N). There was no significant difference between the groups regarding the pattern of root fracture (P=0.39). However, site and extent of fractures were significantly different among the groups (P<0.05). Conclusion: The conventional cements provided optimal retention and caused less root damage after post removal. Thus, cements providing adequate retention and allowing easier post removal are recommended for use in endodontically treated teeth with a possibility of requiring retreatment.

Fracture strength of teeth restored with milled ultrathin occlusal veneers made of polymer-infiltrated ceramic

The purpose was to evaluate, in vitro, the fracture strength of teeth restored with 0.3- or 0.6-mm-thick occlusal veneers made of Vita Enamic® bonded to enamel or dentin. Fifty third molars were allocated into five groups (n=10): Group C - control (sound teeth); Group 0.3E - 0.3-mm-thick occlusal veneers bonded to enamel; Group 0.6E - 0.6-mm-thick occlusal veneers bonded to enamel; Group 0.3D - 0.3-mm-thick occlusal veneers bonded to dentin; Group 0.6D - 0.6-mm-thick occlusal veneers bonded to dentin. After luting with Single Bond Universal and Filtek Z-100, the samples were subjected to fracture strength test in a universal testing machine. The fractures were classified as irreparable and reparable. Data were analyzed with 2-way and 1-way ANOVA (α=.05) followed by Tukey’s test. The teeth restored with 0.3-mm-thick occlusal veneers (2658 N) achieved significantly higher fracture strength compared to the teeth restored with 0.6-mm-thick occlusal veneers (2070 N) (p=0.017). The teeth restored with occlusal veneers bonded to enamel (2648 N) had significantly higher fracture strength compared to the teeth restored with occlusal veneers bonded to dentin (2049 N) (p=0.015). Group C (3355 N) and Group 0.3E (2965 N) did not differ significantly from each other, being the fracture strength significantly higher than the other groups (p<0.05). The fractures were predominantly reparable. The teeth restored with 0.3-mm-thick occlusal veneers achieved higher fracture strength compared to the teeth restored with 0.6-mm-thick occlusal veneers. The supporting substrate influenced the fracture strength, which was higher for the teeth restored with occlusal veneers bonded to enamel.

Stress analysis of over-denture abutments treated with two obturation techniques

Aim: Evaluation of stresses induced on over-denture abutments endodonticaly treated with two different obturation techniques.Materials and methods: eight mandibular permanent canines were inserted in four pesudo-realistic models. In each model two canines were placed in it. One canine was treated with lateral obturation technique and the other canine with vertical obturation technique. Four over-denture prostheses were fabricated on the four models. Then strain gauges were attached on the coronal one third of the root buccally and lingually for all eight canines. A metal rod was placed occlusally on the premolar –molar area, and a 50 N load was applied on the middle of the rod using the universal testing machine. Readings were collected. Results: from the collected data the lateral obturation showed 85.25±104.901 µε and the vertical obturation showed 4.875±3.555 µε with significance difference of P<0.05 between the groups.Conclusion: it can be concluded that the abutments treated with vertical obturation techniques reduced the stresses induced to the supporting structures when compared with the lateral condensation technique.

Comparison of Microleakage and Compressive Strength of Different Base Materials

This study compared the microleakages and compressive strengths of various base materials.<br/>To evaluate microleakages, 50 extracted permanent premolars were prepared. The teeth divided into 5 groups of 10 each according to the base materials. Cavities with a 5.0 mm width, 3.0 mm length, and 3.0 mm depth were formed on the buccal surfaces of the teeth. After filling the cavities with different base materials, a composite resin was used for final restoration. Each specimen was immersed in 2% methylene blue solution and then observed under a stereoscopic microscope (× 30). To evaluate the compressive strength, 5 cylindrical specimens were prepared for each base material. A universal testing machine was used to measure the compressive strength.<br/>The microleakage was highest in the Riva light cure^TM group and lowest in the Biodentine^TM and Well-Root^TM PT groups. For the compressive strengths, in all groups, acceptable strength values for base materials were found. The highest compressive strength was observed in the Fuji II LC^TM group and the lowest strength in the Well-Root^TM PT group.

Desain dan Pembuatan Papan Tiruan dari Bahan Komposit Laminate Diperkuat Lembaran Batang Pisang

Pada saat ini, pemanfaatan bahan-bahan limbah pertanian yang ramah lingkungan dan mudah terurai di alam menjadi perioritas utama pengembangan bahan-bahan alternatif untuk rekayasa teknik. Wilayah Indonesia merupakan penghasil produk pisang yang terbesar dan berpotensi menghasilkan limbah batang pisang yang melimpah dalam setiap panennya. Dalam studi ini, penyelidikan bertujuan untuk mendesain papan tiruan dari limbah batang pisang, mencetaknya menjadi papan tiruan, dan menguji kekuatan mekaniknya. Desain produk berdasarkan ketebalan papan komersial ialah 50 mm. Pembuatan papan tiruan dengan menggunakan alat cetakan khusus metode tekan. Pengujian kekuatan lentur menggunakan alat uji Universal Testing Machine dengan metode bending tiga titik. Hasilnya diperoleh papan tiruan yang mengalami penambahan ketebalan 10% dari tebal awal yang disebabkan karakteristik batang pisang yang memiliki rongga udara. Apabila dibandingkan dengan papan komersial, papan tiruan yang dihasilkan memiliki kemampuan peredaman yang cukup baik terhadap beban yang diberikan sehingga perlu penyelidikan lebih lanjut untuk pengembangan bahan ini menghasilkan kualitas papan yang lebih baik.

Effect of Adhesive Boosters on Bond Strength of Bleached Teeth in Orthodontic Bonding

Objectives: To evaluate and compare the effect of adhesion boosters on shear bond strength (SBS) of orthodontic brackets on bleached teeth. Materials and Methods: A sample of 90 extracted maxillary premolars was equally divided into 2 groups of bleached and non-bleached teeth. Twenty-two percent carbamide peroxide gel was used as an agent for bleaching. Each group was further divided equally into 3 subgroups depending on the type of adhesive booster used (Enhance LC, All-bond 2, and no adhesive booster [control]) and maxillary premolars brackets were bonded. Debonding was done with a universal testing machine, and the SBS was recorded. Results: The SBS of non-bleached teeth was highest for All-bond 2 (14.78 ± 2.47 MPa) followed by Enhance LC (13.15 ± 3.49 MPa) and control (10.30 ± 1.06 MPa). The SBS of bleached teeth was highest for All bond 2 (12.23 ± 1.41 MPa) followed by Enhance LC (11.76 ± 1.71 MPa) and control (9.63 ± 1.06 MPa). All subgroups showed a significant difference in SBS (P = .000) on bleached and non-bleached teeth. The SBS showed a significant difference between the bleached and non-bleached teeth in All-bond 2 group (P = .019). Conclusion: Adhesive boosters increased the SBS of both bleached and non-bleached teeth significantly. Among the two adhesive boosters used, All-bond 2 showed more SBS values.