Background and objectives: Dimensional changes associated with the processing of complete dentures is one of most important problems of acrylic resin denture base materials, these changes lead to series of problems clinically. The aim of this study was to try new attempts to minimizing the post processing dimensional changes. Methods: Forty-two identical maxillary waxed dentures prepared, each of them mounted on an articulator. The initial dimension was measured between the upper and lower members of the articulator before processing, after processing and remounting of the dentures the measurements recorded after deflasking and decasting, comparing these measurements with the initial measurement determined the incisal pin opening (IPO). Two new attempts for decreasing IPO have been tested by modifying the conventional waxed dentures, in the first attempt five wax sprues added to the flanges while in the second attempt four wax sprues added to the palatal surfaces of the waxed dentures. The waxed dentures processed in two types of heat curing acrylic resins. Results: The results showed that both new attempts caused decreasing in the dimensional changes and IPO at both times after deflasking and decasting. Conclusion:It had been concluded that the addition of four waxed sprues will significantly decrease the IPO.

Background and objectives: Cobalt chromium removable partial denture has been in use for years and despite of the advantages that cobalt chromium provides, it has many disad‐ vantages. In the recent years flexible removable partial denture has been introduced to dentistry with many advantages over cobalt chromium removable partial denture . The purpose of this study was to evaluate the effect of cobalt chromium and flexible removable partial denture on chewing activity and muscle efficiency. Methods: Ten patients were selected, all of them had completely edentulous maxilla and Kennedy Class I partially edentulous lower arch. eight male and two females with their ages ranging from 45 to 60 years. For each patient, an upper complete denture and two lower removable partial dentures (cobalt chromium and flexible) were constructed. Once the dentures were completed, muscle efficiency with the use of Electromyography and chew‐ ing activity by sieving method was performed in scheduled visits. Statistical analysis of data was achieved by means of (SPSS 25). And performing (independent sample T test, one‐way anova test, and multiple comparison Tukey test). Results: The chewing activity test, revealed a statistically significant difference (P< 0.05) between first and fourth visit concerning the flexible partial denture and improvement of chewing, for the cobalt chromium removable partial denture although there was improve‐ ment of chewing but it was not significant. Regarding the muscle efficiency test, this test revealed that there was no major significance between flexible and cobalt chromium re‐ movable partial denture and they are almost the same, but we can notice improvements of muscular efficiency specially in masseter muscle. Conclusions: Within the limitations of this study, it has been concluded that the muscle efficiency is improved within one month of insertion of both types of removable partial denture . Both flexible and cobalt chromium dentures increased muscle efficiency. Flexible removable partial denture increased chewing activity slightly better than cobalt chromium, while cobalt chromium was marginally better at chewing of hard food comparing to flexible denture.

. IntroductionPatient needs a removable denture for the purpose of functional, psychological or financial. Construction of an esthetic removable denture with minimal display of conventional metal clasp makes a challenge to the dentist. 1 Continous research in polymer science has provided "Acetal resin" (Polyoxymethylene (POM)), which is made by the polymerization of formaldehyde and is a thermoplastic technopolymer with a monomer-free crystalline structure.2 Acetal resin is a thermoplastic and injection moulded resin. It has been used as alternative denture base and denture clasp material since 1986. It was used as a clasp material due to superior aesthetics which made the clasp match the shade of the abutment tooth.3 It is very strong, resists wear and fatigue, in addition to flexiblity, which makes it the best material for pre-formed clasps of partial denture, unilateral partial denture, provisional bridges, implant abutments, occlusal splints and orthodontic appliances.4 Acetal resin and polymethyl methacrylate (PMMA) are radiolucent materials that cannot be seen using standard radiographic techniques. So in cases of accidental ingestion, aspiration traumatic impactions of the dental appliance, it is difficult to be detected and requires invasive procedures as advanced imaging techniques. Delay in localizing or removing the foreign body may be harmful to the life. 5 Much research has been carried out to incorporate radio-opaque material such as metals, iodobenzene, polybarium acrylate and barium sulphate into the acrylic resin to fabricate a reasonable radio-opaque denture base material. 6 The effect of radiopaque material with the BaSO 4 was tested on the mechanical and physical properties of Background and objective: Acetal resin or polyoxymethylene is a flexible thermoplastic radiolucent denture base material. This study aimed to evaluate the addition of barium sulfate BaSO 4 nanoparticles on the mechanical and physical properties of acetal resin. Methods: Forty two specimens were prepared from both non-modified and modified acetal resin. The tested specimens were obtained by melt extrusion into the mold equipment followed by injection molding. The radio-opacity of non-modified and modified evaluated, and then some mechanical and physical properties tested. Results:The results of radio-opacity test showed that the radiographic density of BaSO 4 3% Acetal resin specimens was at the same level of 2mm thickness of the aluminum stepwedge. Non-significant decrease noted in surface roughness, creep in all strain regions, and compressive strength and modulus of elasticity. Conclusion: It has been concluded that the addition of 3% BaSO 4 nanoparticles produced an acceptable radio-opaque Acetal resin denture base material. Although the addition caused some changes in properties, the modified Acetal resin remained as a flexible thermoplastic material.

Background and Objectives: The loss of natural teeth causes many problems; one of major problems that are associated with edentulousness is the hypotonicity of muscles of mastication and decreasing the ability of the patient to chew food properly. Treatment of edentulous patients with complete denture will increase the muscle tonicity and chewing activity. The purpose of this study is to clinically compare patient's chewing ability between lingualized occlusion complete denture and bilaterally balanced occlusion complete dentures. Materials and methods: Two sets of complete dentures with different occlusions were fabricated for ten patients. The patients received bilaterally balanced occlusion (BBO) complete denture and lingualized occlusion (LO) complete denture in random order. The patients wear each set of complete denture for one month. During this month, chewing activity tests were performed for the patients in four different time intervals. The results of these tests were analyzed using t-test and paired t-test to compare between the lingualized occlusion and bilaterally balanced occlusion complete denture and also to compare the results of each time interval with each other. Results: The mean amount of the walnuts that passed through the sieve in LO dentures were (1.78g), during the fourth visit while it was (1.18g) in BBO. There were statistically significant difference between LO and BBO schemes of complete denture when measuring the amount of the chewed walnuts that passed through the sieve in second, third and fourth visit (p=0.037, 0.001 and 0.000). Conclusion: Within the limitations of this study, it has beenconcluded that the chewing ability was higher in patients who were provided with complete dentures fabricated with the LO scheme as compared to those patients who received complete dentures made with BBO scheme. This was due to the fact that LO technique resulted in functionally better complete dentures as compared to the ones made by BBO technique

Objective: This study aims to evaluate patient satisfaction when treated with implant-supported restorations at Dental Implant Unit- Maxillofacial Surgery Department/Rizgary Teaching Hospital in Erbil-Iraq from 2015-2019.   Methods: Eighty patients with implant-supported prostheses were randomly selected to participate in the study. A case sheet was created for each of them. The case sheet consisted of two parts. The first part consisted of clinical evaluation recordings: mobility, suppuration, and bleeding on probing the implant-supported prosthesis, which the examiner did. While the second part of the case sheet was a questionnaire that the patient answered. There were five questions in the questionnaire: 1- the ability to chew foods, 2- the appearance of the prosthesis, 3- the comfort of the implant-supported prosthesis, 4- speaking ability, and 5- overall satisfaction with the outcome of the treatment. The degree of satisfaction was assessed by the scale from (1-5) with 1: corresponding to Not satisfied at all, 2: Not satisfied, 3: Partially satisfied, 4: Satisfied, and 5: Highly satisfied.       Results: Majority (75%) of the sample were either satisfied (30%) or highly satisfied (45%) with the outcome of treatment (overall satisfaction). Nearly the same percentages were obtained regarding the satisfaction with the ability to chew foods, the appearance of the prosthesis, comfort, and speaking ability with the implant-supported prosthesis. In addition, there were strong correlations between mobility and suppuration of the implant-supported prostheses and the patient's satisfaction..   Conclusions: Within the limitation of this study, it has been concluded that patients treated with implant-supported prostheses were highly satisfied with the treatment. Data on patient satisfaction is an important source of information that can guide dentists to provide treatment that will meet patients' expectations more.