Conical Head Research Articles

Effect of Abutment Screw Design and Crown/Implant Ratio on Preload Maintenance of Single-Crown Screw-Retained Implant-Supported Prostheses.

New solutions need to be developed for cases in which implants that were placed years ago are now presenting prosthetic complications. A conical head screw design for a single-tooth abutment was developed to preserve the initial applied torque. The aim of this study was to assess the preload maintenance of different screw design sets (a conical head screw set and a flat head screw set) for single-tooth abutments in external hexagon implants, verifying whether reverse torque changes after mechanical loading at different crown/implant ratios and to understand if the use of the tested conical head screw set design can help clinicians solve loosening torque. Forty external hexagonal implants, 40 single-tooth abutments, 20 conical head screws, and 20 flat head screws were split into four groups with different crown/implant ratios (crown/implant ratio > 1 or crown/implant ratio < 1). The abutments were attached to the implants by applying a torque of 35 Ncm; the specimens were mechanically loaded for 1 million cycles, and the loosening torque was checked and recorded with a digital torque wrench. The Kruskal-Wallis test (P = .05) and Wilcoxon test were performed to assess the results. In all groups, at least one specimen kept 100% of the initial applied torque before mechanical loading (t0). After mechanical loading (t1), all specimens presented torque reduction. The Kruskal-Wallis test was performed, and the flat head screw t0 group presented lower torque maintenance and a significant difference (P < .05) compared with the initial applied torque and with the conical head screw t0 group. The conical head screw t0 group presented a higher torque maintenance and no significant difference (P > .05) compared with the initial applied torque. For the flat head screw, the crown/implant ratio affected the torque maintenance. For the conical head screw, the crown/implant ratio did not affect the torque maintenance (P > .05). The conical head screw set presented a higher maintenance of applied preload than the flat head screw set. As far as reverse torque is concerned, the crown/implant ratio affects the torque maintenance only in association with a flat head screw set. The use of the tested conical head screw set can help clinicians solve loosening torque, mainly in a situation with a crown/implant ratio > 1.

Development of a non-isothermal forging process for hollow power transmission shafts

This paper presents a new forging process for hollow power transmission shafts. The key aspect of the process is altering the flow characteristics of the material via differential heating of the tubular stock. The process is conceived in three main stages namely, partially heat the tubular stock with induction heating; upset the heated section of the tube to form a solid section; and finally shape the solid section into a flange or a conical head by further upsetting the workpiece. Parametric study was also carried out for various internal diameter to external diameter (ID/ OD) tube ratios. With the aid of finite element analysis (FEA), the feasibility of the process was evaluated based on formability, forming loads and dimensional accuracy. FEA results showed that it is feasible to produce hollow axle shafts, stepped gear shafts, and pinion gear shafts. Scaled down models of hollow axle shaft and hollow pinion gear shaft were successfully fabricated using the proposed methodology.

Truncated Conical PVDF Film Transducer for Air Ultrasound

In this paper, a truncated conical polyvinylidene fluoride (PVDF) film transducer for air ultrasound is investigated. The transducer was designed and fabricated using two identical pieces of fan-shaped PVDF film that makes the curve direction as consistent as possible with the molecular orientation direction of the film. The transducer has a truncated conical geometry, which provides a wide bandwidth with wide vertical beam angle. Measurements of the frequency response of transmitter output, angular performance, and pulse response are presented. The results show that the radiation directivity pattern of the transducer is in the axial direction of the conical film and the beam width is 140° at −6dB level, which is more than that of the commercial 40-kHz ceramic transducers and cylindrical PVDF transducers. Therefore, this ultrasonic transducer is well-suited for three-dimensional (3D) ultrasonic positioning systems, and in particular for mounting at the conical head of electronic pens as an ultrasonic position transmitter.

Phytochemicals and antioxidant activity in four varieties of head cabbages commonly consumed in China

Head cabbage (Brassica oleracea var. capitata) is a cruciferous leafy vegetable consumed commonly in China. It has been suggested that diets rich in cabbages play an important role in disease prevention. The phytochemicals as well as antioxidant activity of four typical varieties of head cabbages in China were systematically investigated. Sinapic acid was the most abundant phenolic acid in all samples followed by iso-ferulic acid. Most phenolic acids in red head cabbage were significantly higher than in other head cabbages. The 5-CH3-H4 folate contents in all samples were much higher than folate. Conical head cabbage contained the highest amount of folic acids while red head cabbage had the lowest. Cyanidin was the only anthocyanidins found in red head cabbage with the content of 44.52 mg 100 g− 1 fresh weight (fw). Total isothiocyanates in flat head cabbage was significantly higher than other head cabbages. Red head cabbage had the significant the highest level of total phenolics and flavonoids with the values of 153.94 mg gallic acid equivalents·100 g− 1 and 51.32 mg rutin equivalents·100 g− 1, respectively, while flat head cabbage had the lowest level. Red head cabbage exhibited the highest antioxidant activity as measured by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) and 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging and ferric ion reducing antioxidant power (FRAP) assays with the values of 69.82, 87.23% and 0.53, respectively. The study suggests that different varieties of head cabbages have different nutritional advantages, and provides useful information to recommend the right head cabbages for consumers.Graphical abstract

INFECTED FRESHWATER SNAILS, BIOMPHALARIA ALEXANDRINA, THE INTERMEDIATE HOST OF SCHISTOSOMA MANSONI

The objective was to study the chromosomes of Biomphalaria alexandrina snails (class Gastropoda) in control and infected state which could be helpful in understanding how host-parasite relationships in feasible and effective control measures. The chromosomal changes were studied using the air-drying method. The results showed that B. alexandrina had a diploid chromosome number, 2n = 36. Also, the meiotic stages were detected as early- leptotene and late leptotene, zygotene, diplotene, metaphase I. The result also revealed the presence of a primitive sperm, with a conical head and a very long, uni-flagellate tail. A comparative meiotic chromosome analysis between the control and infected ones showed some significant differences, as pachytene and diplotene were more condensed.

An experimental and simulation study of impact resistance in sandwich structures casing

As the main force component on the aeroengine, casing is one of bases of the whole aeroengine, but it is extremely difficult to analyze the capacity of aeroengine casing impact resistance. An experimental and simulation study of impact resistance has been conducted on sandwich structures casing with aluminum honeycombs to identify and improve aeroengine casing impact resistance. Firstly, a Rent–Ipson model has been applied to analyze the energy of broken blades with impacting casing. Based on a sensing test technology, the experimental research on the impact of aluminum honeycomb sandwich panel with a conical head shape bullet and a hemispherical head shape bullet have been carried out. The experimental results provide a basis for subsequent simulation research. Then the impact resistance have been compared and analyzed from single structure casing, double layer structure casing, and sandwich structure casing, according to their loss of blade kinetic energy, casing deformation, and the variation of casing internal energy. Finally, the variation of energy has been discussed during blade impacting casing with various oblique angles. Our results show that the impact resistance of sandwich structure casing is better than single structure casing and double layer structure casing. Most importantly, the impact resistance of casing has been improved with the increase of blade impact oblique angle.

The ultrastructural features of embryonic and early larval development in Yesso scallop, Mizuhopecten yessoensis.

Fine structural features of Mizuhopecten yessoensis in different embryonic and larval developmental stages from oocyte to early veliger have been studied. Spermatozoa have a conical head, consisting of a short acrosome, nucleus, and 4 mitochondria in the middle piece. The flagellum is approximately 40 μm in length. Oocyte cytoplasm contains numerous yolk granules, which are gradually expended during the larval development and disappear at the early veliger stage. Gastrula has two invaginations: shell gland anlage on the dorsal side and ventral side archenteron. Prototroch of a trochophore consists of two ciliary rings. Telotroch is absent. Myoblasts containing bundles of myofilaments are found in the blastocoel of trochophore. Velum and shell begin forming at the late trochophore stage. Cells of gut epithelium form numerous microvilli, organized into a brush border structure on the surface of enterocytes. A suggestion is made that larvae at the late trochophore stage are capable of digesting food and feeding. The structure of a M. yessoensis veliger is typical for pectinids. The velar retractor muscles have cross striation with a period of 1 μm. The digestive system of an 8-day-old veliger consists of the esophagus, stomach (with subdivided gastric shield and style sac), and short intestine. The digestive gland (with no discernible loops at this stage) is a part of the stomach epithelium with two types of digestive enzyme-producing cells.

Development of a Novel Guided Wave Generation System Using a Giant Magnetostrictive Actuator for Nondestructive Evaluation.

As a common approach to nondestructive testing and evaluation, guided wave-based methods have attracted much attention because of their wide detection range and high detection efficiency. It is highly desirable to develop a portable guided wave testing system with high actuating energy and variable frequency. In this paper, a novel giant magnetostrictive actuator with high actuation power is designed and implemented, based on the giant magnetostrictive (GMS) effect. The novel GMS actuator design involves a conical energy-focusing head that can focus the amplified mechanical energy generated by the GMS actuator. This design enables the generation of stress waves with high energy, and the focusing of the generated stress waves on the test object. The guided wave generation system enables two kinds of output modes: the coded pulse signal and the sweep signal. The functionality and the advantages of the developed system are validated through laboratory testing in the quality assessment of rock bolt-reinforced structures. In addition, the developed GMS actuator and the supporting system are successfully implemented and applied in field tests. The device can also be used in other nondestructive testing and evaluation applications that require high-power stress wave generation.

Prediction of Aerodynamic Characteristics for Slender Bluff Bodies with Different Nose Cone Shapes

In this work, the numerical approach is used to verify the aero/hydrodynamic performance of different geometries of nose cones. Computational methods predict the flow characteristics fairly accurately in order to validate the data obtained from experiments. The simulation involves muzzle velocity that range from 5 m/s to 25 m/s the corresponding Reynolds numbers ranges from 1.69 to 8.4 x 105 and calculated for the different angle of attack, -10 to 20 degrees, to demonstrate the flow behavior around the different nosecone shaped shells. Nosecone is the most forward section of any slender moving bodies which are used in rockets, guided missiles, submarines, aircraft drop tanks and aircraft fuselage to reduce the aerodynamic or hydrodynamic drag. The basic geometry of bluff body is cylinder with variant nosecone shapes such as flat and tapered head, with moderate to low taper ratios and conical head. The aerodynamic characteristics like lift, drag and pressure distribution of the cylinder with different nosecones are illustrated for low subsonic speed for the same length to diameter ratio. The best results are obtained for cylinder with conical nosecone and better similar results observed for cylinder with shapes having low and medium taper.

Development of a Non-isothermal Forging Process for Hollow Power Transmission Shafts

This paper presents a new forging process for hollow power transmission shafts. The key aspect of the process is altering the flow characteristics of the material via differential heating of the tubular stock. The process is conceived in three main stages namely, partially heat the initial tubular stock with induction heating; upset the heated section of the tube to form a solid section; and finally shape the solid section into a flange or a conical head by further upsetting the workpiece. Parametric study was also carried out for various ID/ OD tube ratios. With the aid of finite element analysis (FEA), the feasibility of the process was evaluated based on formability, forming loads and dimensional accuracy. The FEA results showed that it is feasible to produce hollow axle shafts, stepped gear shafts, and pinion gear shafts.

Инициирование детонации в зарядах взрывчатых веществ высокоскоростными ударниками с конической головной частью

Инициирование детонации в зарядах взрывчатых веществ высокоскоростными ударниками с конической головной частью

First Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in Ohio

HomePlant DiseaseVol. 101, No. 7First Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in Ohio PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of a Pin Nematode (Paratylenchus neoamblycephalus) From Soybean in OhioK. E. Ankrom, H. Lopez-Nicora, T. L. Niblack, and L. E. LindseyK. E. AnkromSearch for more papers by this author, H. Lopez-NicoraSearch for more papers by this author, T. L. NiblackSearch for more papers by this author, and L. E. LindseySearch for more papers by this authorAffiliationsAuthors and Affiliations K. E. Ankrom , Department of Horticulture and Crop Science, Ohio State University, Columbus 43210 H. Lopez-Nicora T. L. Niblack , Department of Plant Pathology, Ohio State University, Columbus 43210 L. E. Lindsey , Department of Horticulture and Crop Science, Ohio State University, Columbus 43210. Published Online:5 May 2017https://doi.org/10.1094/PDIS-12-16-1728-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In a statewide soybean survey in June of 2013, 2014, and 2015, 588 soil samples were collected from fields planted to soybean (Glycine max) in 36 counties representing the soybean production area of Ohio. The soil had variable amounts of sand, silt, and clay, and the fields were planted to corn (Zea mays) or soybean during the previous year. Nematodes were extracted from 100 cm3 soil from each sample by decanting and sieving followed by sucrose centrifugal flotation. Phytoparasitic nematodes were identified and counted based on morphological traits to genus at 40× to 100× magnification. Pin nematodes (Paratylenchus spp., family Tylenchulidae) were detected in 69, 52, and 36% of fields sampled in 2013, 2014, and 2015, respectively. Paratylenchus species can cause substantial crop loss (Braun and Lownsbery 1975; Wang et al. 2016). Females accounted for a large percentage (>50%) of the Paratylenchus populations in some soybean samples, which suggested that they were actively reproducing on soybean. The maximum number of Paratylenchus observed in a single sample was 3,346/100 cm3 soil; the nematode was initially identified as P. projectus, which reduced soybean yield at lower population densities (Niblack 1992). Individuals from one sample were hand-picked and identified to species under a compound light microscope as P. neoamblycephalus Geraert (Ghaderi et al. 2014). The females (n = 20) had conical truncate heads, strong spears (s = 29.3 to 33.9 μm, mean = 31.4 μm), and rounded basal knobs. The cuticles were distinctly annulated, with lateral fields containing 4 incisures. Present were single, outstretched ovaries as well as posteriorly located vulvae (mean v = 83.2). Spermathecae were present without sperm and no males were observed. The anus was often obscure, with tail conical and tapering in shape. Body length ranged from 349.6 to 435.0 μm (mean = 397.0 μm). These morphological traits were consistent with Paratylenchus observed from all the Ohio fields. DNA was extracted from five adult females (n = 5) and the 18S rRNA region was amplified with the 5′-3′sequence of the 18s primer pair, forward: CGAATRGCTATTACAACAGC (23 bases); and the reverse: GCGGTATCTGATCGCC (18 bases). PCR products were purified, sequenced, and deposited in GenBank (GenBank accession no. KY584087). The sequence was compared with previously deposited sequences by means of a BLASTN search, which resulted in a 97% identity match with P. neoamblycephalus (AY284634.1). No previously deposited sequence for the D2/D3 molecular marker for the 28S rRNA region existed for P. neoamblycephalus; ours is the first deposited for this marker region (KY584086). One soil sample with 150 P. neoamblycephalus/100 cm3 soil was used to infest soybean cultivar Lee 74. After 12 weeks in a greenhouse maintained at 27°C, the P. neoamblycephalus population increased to more than 1,000/100 cm3 soil (reproduction factor [RF] 6.7). This increase was split into three pots (∼300 P. neoamblycephalus/pot) of Lee 74, and after 10 weeks at 27°C each pot had RF >1 (1.3 to 6.9). The molecular and morphological observations confirmed the presence of P. neoamblycephalus in the sample, and the greenhouse tests confirmed soybean as a host. The nematode has been reported from commercial vegetables in Tennessee (Bernard 1980), but not from soybean. Management recommendations for soybean will depend on its distribution and pathogenicity. To our knowledge, this is the first report of P. neoamblycephalus in Ohio and as a parasite of soybean.

Study of the expansion characteristics of a pulsed plasma jet in air

In the background of electrothermal-chemical (ETC) emission, an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air. The evolutionary process of the plasma jet is experimentally investigated using a piezoelectric pressure sensor and a digital high-speed video system. The variation relation in the extended volume, axial displacement and radial displacement of the pulsed plasma jet in atmosphere with time under different discharge voltages and jet breaking pressures is obtained. Based on experiments, a two-dimensional axisymmetric unsteady model is established to analyze the characteristics of the two-phase interface and the variation of flow-field parameters resulting from a pulsed plasma jet into air at a pressure of 1.5–3.5 MPa under three nozzle diameters (3 mm, 4 mm and 5 mm, respectively). The images of the plasma jet reveal a changing shape process, from a quasi-ellipsoid to a conical head and an elongated cylindrical tail. The axial displacement of the jet is always larger than that along the radial direction. The extended volume reveals a single peak distribution with time. Compared to the experiment, the numerical simulation agrees well with the experimental data. The parameters of the jet field mutate at the nozzle exit with a decrease in the parameter pulse near the nozzle, and become more and more gradual and close to environmental parameters. Increasing the injection pressure and nozzle diameter can increase the parameters of the flow field such as the expansion volume of the pulsed plasma jet, the size of the Mach disk and the pressure. In addition, the turbulent mixing in the expansion process is also enhanced.

Construction Technology Research on Revolving Conical Pullout Anchor

To solve the anti-float problems of underground buildings (structures) more economically, environmentally and effectively. The paper putted forward a construction technology of revolving conical pullout anchors based on researching and improving to the traditional pullout measures. That was a method that the conical anchor head was installed on the drilling pipe and screwed into the stable soil under the influence of drilling pipe. When pulling the drilling pipe, the fine aggregate concrete were poured into the edge. Furthermore, prestressed anchor cable should be strained which connected with the anchor head to keep a good connect with the beam so that it could improve pullout capacity. The conundrums of long construction period and high cost had effectively solved. This technique also had provided great reference values for the congener construction.

Few Comments on Metrics and Optimizing of Simple Conical Heads of Circular Columns for Beamless Reinforced Concrete Monolithic Slabs

This paper deals with dimensional aspects of circular column heads supporting beamless reinforced concrete monolithic (also locally supported) slabs with regard to their stressing in terms of the so-called bursting safety, and it analyses possibilities of their metrics and shape optimizing. Presented concept challenging mathematical solution for calculation of stress distribution through column head and its surrounding, based the theory of failure. Methodology of analysis provides theoretically adjusted guidance how to design and optimize column heads in economical way.

Comparative ultrastructure of spermatozoa from two regular and two irregular New Zealand echinoids

Spermatozoa from four species of echinoids found in New Zealand had morphological characteristics typical of other echinoids, including a conical sperm head with an acrosome-capped nucleus, a midpiece, and a single long flagellum. The spermatozoa of Fellaster zelandiae, Echinocardium cordatum, Evechinus chloroticus, and Centrostephanus rodgersii also showed statistically significant differences in species-specific morphological characteristics. Evechinus chloroticus showed the most variable sperm morphology. The irregular urchins (F. zelandiae and E. cordatum) had short, wide sperm heads (head length:width ratios 2.93:1 & 2.97:1, respectively) with a long acrosome complex, while the regular urchins (E. chloroticus and C. rodgersii) had longer, narrower heads with a short acrosome complex (ratios 5.29:1 & 3.37:1). Spermatozoa of E. cordatum from the New Zealand population shared more characteristics with those of conspecifics from the Sea of Japan than those of conspecifics from the Baltic, reflecting the membership of the former two populations in a distinct Pacific clade. Volumetric calculations showed no evidence of phylogenetic grouping. Mitochondria of E. chloroticus spermatozoa were less than half the volume of those of C. rodgersii and E. cordatum, and those of F. zelandiae were intermediate in volume. These volume measurements will be useful in physiological studies of sperm performance and quality.

Studies of flow and cavitation in hydraulic lift valve

This paper presents the results of experimental studies of the phenomena connected with the flow of the working medium in the throttling orifice of the conical head-bevelled or feather-edged seat unit. The critical Reynolds number demarcating the laminar flow from the turbulent flow for the particular conical head-bevelled or feather-edged seat units has been determined on the basis of visualization studies. The dependence between flow ratio Cv and the Reynolds number has been determined for the dilation angle of the conical valve heads and the length of the seat generating line. Acoustic and cavitation tests have shown that valve heads with the smallest dilation angle and the highest critical velocity are characterized by the lowest level of noise in the throttling orifice at which cavitation occurs.

The use of non-linear inverse problem and enthalpy method in GTAW process of aluminum

This work presents an alternative approach for the thermal analysis of the GTA (Gas Tungsten Arc) welding process on a 6065 T5 aluminum alloy. For this purpose, a C++ code was developed, based on a transient three-dimensional heat transfer model with phase change and mobile heat source. The thermal model took into account the dependence of thermal properties on temperature and heat losses by convection and radiation. The convection heat transfer coefficient and the emissivity were also considered variables with the temperature. To estimate the amount of heat delivered to the plate, the BFGS (Broydon–Fletcher–Goldfarb–Shanno) technique was used. Moreover, an analysis of the duration time of the electrode in positive (t+) and negative (t−) polarities was carried out. The methodology was validated by accomplishing lab controlled experiments. The aluminum samples lay on four conical head screws and submitted to a heat flux on one surface by the GTAW process torch. The torch displaces along the sample, thus simulating a real process. The numerical results presented low deviation when compared to the experimental results, which in turn, confirm the validation of the methodology for the study of the welding process presented.

A new complication in volar locking plating of the distal radius: longitudinal fractures of the near cortex

The purpose of this study was to document a new complication in volar locking plating of the distal radius. Between January 2007 and January 2014, 223 patients were identified from the department's surgical database with retrospective chart and radiographic review. Sixty-eight patients were over 60 years of age. All fractures were operated with Acu-Loc® (Acumed, Hillsboro, OR, USA) wrist volar locking plating systems. Longitudinal fracture lines (LFL) beneath volar plate-extending proximal shafts were documented. Correlations between age groups and LFLs were investigated. Radiographs with LFLs were assessed at final follow-up for the following parameters: volar tilt, radial inclination and radial length. Twenty-eight of 68 patients over age of 60 years had LFLs. Correlation was significant for age groups (p<0.05). The effect of these fracture lines on radiographic parameters was not significant (p>0.05). Surgeons should be aware of the complications that may occur with volar locking plates. Understanding of potential complications and their results are important. As a result of aging, thinning, and weakening, the near cortex may become more brittle. When the plate is reduced on the bone with a nonlocking screw, the conical head of diaphyseal locking screws can extend over plate thickness and penetrate the near cortex, acting as a screwing wedge. Additional divergent configuration may promote this effect and crack the cortex.

내부 원추형 연결형태 임플란트에서 지대주 나사머리의 좌면각도가 연결부 기계적 안정성에 미치는 영향

목적: 내부 원추형 연결형태 임플란트에서 지대주 나사의 좌면각도가 연결부의 기계적 안정성에 미치는 영향을 알아보기 위함이다. 연구 재료 및 방법: 원추형 연결구조 티타늄 임플란트와 시멘트 유지형 지대주, 텅스텐 카바이드 코팅된 티타늄 합금 지대주 나사를 사용하였다. 좌면각도가 <TEX>$45^{\circ}$</TEX>와 <TEX>$90^{\circ}$</TEX>를 갖는 지대주와 지대주 나사를 제작하여 30 Ncm 조임회전력으로 지대주를 체결한 후 하중을 가하고 체결 및 하중 부여에 따른 침하량을 측정하였다(n = 5). 유압식 피로시험기에 임플란트를 고정하고 스테인리스 스틸 금속관을 지대주에 합착하였다. 이 후 반복 하중을 가한 후 풀림토크 변화량을 측정하고, 압축굽힘강도와 피로강도를 측정하였다(n = 5). 결과: 지대주 침하량은 지대주나사 체결 시 가장 크게 나타났으며(P < 0.05), 나사체결과 하중부여에 따른 총 침하량은 <TEX>$45^{\circ}$</TEX>군보다 <TEX>$90^{\circ}$</TEX>군에서 더 크게 측정되었다(P < 0.05). 반복하중 부여 후 풀림 토크, 그리고 최대 압축굽힘강도와 피로강도는 통계적으로 유의한 차이를 보이지 않았다(P > 0.05). 결론: 본 실험조건하에서 지대주 나사머리의 원추형 설계가 지대주의 총 침하량을 약간 감소시키는 효과를 나타냈으나, 연결부의 전체적인 기계적 안정성에 미치는 영향은 크지 않을 것으로 판단된다. This study is to evaluate how different bearing surface angles of abutment screw affect the mechanical stability of the joint in the conical seal design implant system. Materials and Methods: Internal connection type regular implants, two-piece cemented type abutments and tungsten carbide/carbon-coated titanium alloy abutment screws were selected. Titanium alloy screws with conical (<TEX>$45^{\circ}$</TEX>) and flat (<TEX>$90^{\circ}$</TEX>) head designs which fit on to abutment were fabricated. The abutments were tightened to implants with 30 Ncm by digital torque gauge. The loading was applied once to the central axis of abutment. The mean axial displacement was measured using micrometer before and after the tightening and loading (n = 5). The abutment was tightened to implants with 30 Ncm and T-shape stainless steel crown was cemented. Then the change in the amount of reverse-torque was measured after the repeated loading to the central axis, and the place 5 mm away from the central axis. Compressive bending and fatigue strength were measured at the place 5 mm away from the central axis (n = 5). Results: Both groups showed the largest axial displacement when abutment screw tightening and total displacement was greater in the flat head group compared to conical head group (P < 0.05). However, there were no significant differences in reverse torque value, compressive bending and fatigue strength (P > 0.05). Conclusion: Within the limitations of this study, the abutment screw head design had no effect on two groups regarding the joint stability, however the conical head design affected the settlement of abutment resulting in the reduced total displacement.