CFD STUDY OF USING DIFFERENT HEAT SINKS FOR ELECTRONIC EQUIPMENTS COOLING

Cooling of Electronic equipment’s is an attractiveresearch area in engineering applications. Continuedminimization of electronic system has resulted in dramaticincrease in the amount of heat generated per unit volume, Theaim of this study is to use computational Fluid Dynamics inorder to draw a CFD model for forced cooling conjugate heattransfer analyses in heat generating electronic systems andcompare between a collection of actual commercial heat sinksdifferent from in geometry ,material , and number of fins .Acomplete computer chassis model with heat sinks and fansinside was created and parametric analyses were performed tocompare the effects of different turbulence models, meshresolutions, and radiative heat transfer. The CFD software wasused, ANSYS Icepack 18.0 for preprocessing and fluent forsolution and post processing. The road map was applied to fivedifferent heat sinks and another three heat sink as a validationmodeled into the full chassis. Numerical results were comparedwith the available experimental data and they were in goodagreement

The effect of two different types of attachments retaining mandibular implant overdentures on measured strains using static loading conditions

Controversy persists as to the design and indications for different attachment systems for overdentures. Overdenture attachment design magnitudes around implants. The purpose of this study was to compare the effects of two resilient stud attachment designs on strain magnitudes around implant retained mandibular overdentures. Two acrylic resin casts were fabricated for use in this study. Two implants 13 mm in length and 3.7 mm in diameter were screwed bilaterally into each cast in the area between the canine and lateral incisor. For the first cast, the Locator attachments were secured to the implants: Model 1. For the second cast, Ball and socket attachments were secured to the implants: Model 2. Electric strain gauges were used to record the microstrains generated in the two models.Four strain gauges were used bilaterally to measure the microstarins produced at the labial,lingual, mesial and distal surfaces of the implants, Furthermore, two strain gauges were installed on the buccal surface parallel to the long axis of the ridge to measure microstarins recorded on the ridge for each cast. A loading device was used to produce standardized static loads within the reported physiologic limits of 50 N on either side of the occlusion rims over the implants directly. The readings of the loaded and unloaded sides were recorded in microstrain units from the multi-channel strain indicator. Microstrains were recorded for both the loaded and unloaded side at each time of load application. With respect to the loaded and unloaded implants, the Locator attachment system showed statistically significant lower values than the Ball attachment system. Regarding the esidual ridge, the Ball attachment system showed statistically significant lower values

CLINICAL & RADIOGRAPHIC EVALUATION OF THE EFFICACY OF LOCALLY APPLIED CHITOSAN AROUND DENTAL IMPLANTS IN CONTROLLED DIABETIC PATIENTS

Background: Oral rehabilitation by dental implants in patients with diabetes remains a controversial issue. Recent advances in biotechnology and study of different biomaterials contribute to the knowledge of what is known today as “tissue engineering.” Chitosan has been used in bone tissue engineering as it promotes growth and mineral rich matrix deposition by osteoblasts. Chitosan is also biocompatible, biodegradable, besides; it’s antibacterial and wound healing effects. Aim of the study was to evaluate the effect of locally applied Chitosan on bone healing around dental implants in controlled diabetic patients. Materials and Methods: Ten completely edentulous controlled diabetic patients participated in this study. Each patient received two implants inserted bilaterally in the mandibular interforaminal area. A split mouth technique was used in this study; Chitosan was applied locally in the right osteotomy sites before implant insertion. mandibular overdentures retained by ball and socket attachments were constructed for all patients. Patients were placed on a recall program for 18-months were clinical assessment, alveolar bone height and bone density around implants were measured using digital radiography.Egyptian dental journa

Influence of platform switching concept on marginal bone alteration around dental implant

The aim of the current study was to investigate the role of the type of abutment/implant connection on the marginal bone loss around dental implant. The present study was conducted on fourteen patients, eight males and six females with age range from 26 to 40 years. Thirty consecutive dental implants were inserted for implant – supported restoration in the posterior maxilla. The dental implants of all subjects were assigned to one of the 3 platform diameters which were 3.8 mm (control group), 4.5 mm (test group A) and 5.5 mm (test group B). At the time of prosthetic rehabilitation, 3.8 mm abutments were connected to the all inserted dental implants. Radiographic assessment of marginal bone level was performed immediately at the time of abutment connection (baseline) and every six months for 24 months after final restoration. Statistical analysis revealed that there was a significant difference between the control group and both test groups as regard the total mean of marginal bone loss in favor of test groups A & B. In conclusion, platform-switching concept seems to have a role in minimizing the marginal bone loss around dental implant

Effect of ozonated plant oil application on implant osseointegration in irradiated bone: an in vivo study

Treatment of malignancies commonly involves radiation therapy. As a result of this therapy the vascular supply to irradiated structures is altered and results in decreased tissue perfusion. In addition to vascular changes, bony structures undergo alteration in osteoblastic and osteoclastic activity. These tissue alteration, enhance the risk of osteoradionecrosis. To avoid this occurrence, many patients who have undergone radiation therapy do not receive elective preprosthetic surgeries, including implant therapy. Ozone, an allotropic form of oxygen, possesses unique properties which are being defined and applied to biological systems as well as to clinical practice.purpose of the study: The purpose of this study was to evaluate the effect of ozonated plant oil on implant osseointegration in irradiated bone. material and methods: 32 titanium screw implants were placed into tibiae bone of 16 experimental New Zealand Albino rabbits assigned to groups I and II, both groups were further divided into 2 subgroups a and b, group Ia was considered control, In group II, the right and left tibiae were irradiated prior to implant insertion, both groups I b & II b received Topical ozonated plant oil. After 4 weeks animals were sacrificed and all specimens were examined under both light microscope and scanning electron microscope. results: Tibiae of the control group, revealed intimate contact of implant with bone in localized areas. Group I b showed intimate contact between the original well formed bone and implant. Architectural alterations were noted in the irradiated groups, where uncalcified newly formed tissue separated implant from bone. Application of Ozone in the irradiated group II b, resulted in the formation of newly formed osteoid tissue. conclusion: The use of implants in conjunction with topical ozonated plant oil in irradiated tissues may provide a mean of enhancing osseointegration

Effect of two different abutment designs on implants supporting mandibular distal extension prostheses

Single implants may be placed at the distal extension of the denture base to minimize the potential for dislodgement of the bilateral or unilateral distal extension partial dentures. The premise is that this will minimize the risk of potential problems of patient discomfort associated with prosthesis retention and stability resulting from residual ridge resorption. Aim of the study: Evaluation of two different abutment designs on marginal bone loss and bone density around implants supporting mandibular distal extension removable partial overdentures. Materials and Methods: Thirty partially edentulous patients with unilateral distal extension and modification area in the other side (Kennedy class II modification 1) were selected for this study. Patients were divided into two groups; Group I: received a distal extension removable prosthesis supported by one implant with conventional dome shaped abutment. Group II: received a distal extension removable prosthesis supported by one implant with a ball and socket abutment. Radiographic evaluation of marginal bone loss and density around all implants in both groups was carried out using digital radiography ( Digora) for one year period every three months interval. Results & Conclusions: After 12 months, Group I showed statistically significantly higher mean amount of marginal bone loss than Group II. A constant increase in bone density values was denoted in both groups through out the whole study period although there was no statistically significant difference between bone density values in the two groups. It can be concluded that the ball and socket abutments showed less marginal bone loss around implants when compared to conventional dome shaped abutments for implant supported mandibular distal extension partial overdentures

AN IN VITRO STUDY OF THE INFLUENCE OF INTERIMPLANT DISTANCE AND IMPLANT LENGTH ON THE STRESSES INDUCED AROUND MANDIBULAR OVERDENTURES IMPLANT

Purpose: A straingauge analysis was performed to investigate the influence of interimplant distance and implant length on stress induced around mandibular overdenture implant . Materials and methods: The stresses were evaluated for three groups, group (A) two implants of length 11 mm were placed at 19, 23 and 29 mm from each other, group (B) two implants of length 13 mm were placed at 19, 23 and 29 mm from each other and group(C) two implants of length 15 mm were placed at 19, 23 and 29 mm from each other. Acrylic casts were constructed representing completely edentulous mandible. On each cast two Implants of same diameter 3.4mm were inserted, upon which complete overdentures supported by ball attachments were constructed. Strain gauges were installed in the labial, lingual and distal sides of each implant to record the strain induced by the applied loads. A special loading device used to produce standardized static vertical load of 60N . The loading positions were located at six points on the occlusal surface (second premolar, P2; first molar, M1; second molar, M2 on the right and left sides). Results: Maximum stress areas were numerically located at the the buccal sides of implants. Increasing implant length gradually from 11 mm to13 mm and to 15 mm decreased the maximum stresses around the implants. Increasing interimplant distances gradually from 19 mm to 23 mm and to 29mm increased the maximum stresses around the implants

EFFECT OF SPLIT PACKING METHOD ON RETENTION OF MAXILLARY COMPLETE DENTURE (IN VIVO AND IN VITRO STUDY)

The dimensional change of maxillary complete dentures remains a problem that may affect retention. The problem is multi-factorial and cannot be totally eliminated. Several methods were proposed to control these changes in order to keep them as minimum as possible. In the present study, a complete split packing method was investigated. The aim was to evaluate the retention of the obtained dentures clinically. 10 edentulous patients were selected; each received 2 heat cured acrylic maxillary dentures that were identical in every aspect except packing method. One maxillary denture was conventionally cured and the other was cured as two split halves that were reassembled by self cure resin. The dentures were examined for retention using a digital force gauge. The results favored the split method, so the second phase of the study was conducted. The aim of the second phase was to evaluate the accuracy of fit at the posterior palatal seal area in vitro using travelling microscope. 10 identical maxillary casts were obtained from a rubber mould. The casts were randomly divided into two groups. Identical maxillary dentures were constructed over these casts. The dentures constructed for the first group casts were split packed, while those for the second group were conventionally packed. The discrepancies at the posterior palatal seal area revealed for group I were significantly less than group II. The clinical and in vitro results suggests that the split packing method of acrylic dentures produces better maxillary denture in terms of posterior palatal seal discrepancies and clinical retention