Ahmed A. Abbas

Bio: Ahmed A. Abbas is an academic researcher from Thammasat University. The author has contributed to research in topics: Acrylic resin & Flexural strength. The author has an hindex of 1, co-authored 2 publications receiving 21 citations.

Comparison of excursive occlusal force parameters in post-orthodontic and non-orthodontic subjects using T-Scan® III

Abstract: Objective: Published studies indicate that orthodontically treated patients demonstrate increased posterior occlusal friction contributing to temporomandibular disorder (TMD) symptoms. This study investigated measured excursive movement occlusal contact parameters and their association with TMD symptoms between non- and post-orthodontic subjects.Methods: Twenty-five post-orthodontic and 25 non-orthodontic subjects underwent T-Scan® computerized occlusal analysis to determine their disclusion time (DT), the excursive frictional contacts, and occlusal scheme. Each subject answered a TMD questionnaire to determine the presence or absence of TMD symptoms. Statistical analysis compared the within group and between group differences (p < 0.05).Results: Statistically significant differences were observed in the disclusion time: DT = 2.69 s in the post-orthodontic and 1.36 s in the non-orthodontic group. In the non-orthodontic group, 72.7% working and 27.3% non-working side contacts were seen, while in th...

Flexural Strength and Dynamic Mechanical Behavior of Rice Husk Ash Silica Filled Acrylic Resin Denture Base Material

Abstract: Silica extracted from rice husk ash (RHA-Si) by pretreatment with hydrochloric acid followed by calcination at 700°C, was prepared. It was investigated with regard to its chemical composition and structure using X-Ray Fluorescence spectroscopy (XRF) and X-Ray Diffractometry (XRD). RHA-Si (0, 0.25, 0.5 and 1% w/w) was incorporated into poly(methyl methacrylate) (PMMA) or acrylic resin powder. Microhardness, flexural strength and dynamic mechanical properties of RHA-Si filled PMMA were then determined. The chemical composition analysis showed that RHA-Si contains a large amount of silica with an amorphous structure. The microhardness of acrylic resin filled with RHA-Si does not change significantly with increasing RHA-Si loading. Flexural strength of filled acrylic resin increases with increasing RHA-Si loadings up to 0.25% w/w. It then decreases with increasing RHA-Si loadings. Dynamic mechanical behavior illustrates that polymer-filler interactions play an important role in reinforcement.

Assessment of occlusion with the T-Scan system in patients undergoing orthognathic surgery

Abstract: Dental occlusion varies among individuals, and achieving correct physiological occlusion after osteotomy is essential for the complex functioning of the stomatognathic system. The T-Scan system records the centre of force, first contact, maximum bite force, and maximum intercuspation. The aim of the present study was to investigate the usefulness and consistency of T-Scan in assessing occlusion before and after orthognathic surgery. Occlusal information was evaluated for 30 healthy adults with normal occlusion and 40 patients undergoing orthognathic surgery. T-Scan had a high degree of reliability for consecutive measurements (Pearson correlation, r = 0.98). For most parameters, occlusal distribution was better after surgery than before surgery. More teeth contributed to occlusion at maximum intercuspation after surgery than before surgery (14 vs. 10). In addition, the difference in the posterior force distribution was reduced after surgery (17.6 ± 13.8 vs. 22.7 ± 21.4 before surgery), indicating better occlusal force distribution after surgery. The maximum percentage force on teeth (p = 0.004) and the number of teeth contributing to occlusion (p < 0.001) also differed significantly. Thus, T-Scan is good for assessing occlusal discrepancies and can be used to portray the pre- and post-operative occlusal contact distribution during treatment planning and follow-up.

Reliability and Validity of T-scan and 3D Intraoral Scanning for Measuring the Occlusal Contact Area.

Abstract: PURPOSE To determine the reliability of T-scan and 3D intraoral scan techniques for assessing the occlusal contact area (OCA), compared to occlusal registration and also to assess the validity of the techniques. MATERIALS AND METHODS Thirty-one dentate adults participated in this cross-sectional study. T-scan records were used to measure the OCA at maximum bite force and at 50% of maximum force using the software's bite force selection tool. A second method measured the OCA between 2 virtual models scanned intraorally using a 3D surface scan and considering the occlusal contact at 2 interocclusal distances (0-100 and 0-200 µm). The third method measured OCA using occlusal registration at moderate and maximum occlusal force, and considering contact at the 2 interocclusal distances (0-100 and 0-200 µm). Images obtained using the 3 methods were analyzed using ImageJ software. Test-retest reliability was assessed by the intraclass correlation coefficient (ICC) and validity by Pearson correlations. RESULTS ICCs ranged from 0.56 to 0.79 (p < 0.001) for the T-scan; 0.37 to 0.61 (p < 0.05) for 3D surface scan; and 0.92 to 0.95 (p < 0.0005) for occlusal registration. The highest OCA values were obtained using the T-scan, and the lowest using the 3D surface scan. Occlusal registration measurements had the highest correlations with those of the other techniques. CONCLUSIONS T-scan is a reliable method for measuring the OCA, but the 3D surface scan is not. Occlusal registration showed a high validity.

The Role of Orthodontics in Temporomandibular Disorders

Abstract: Temporomandibular Disorder (TMD) is the main cause of pain of non-dental origin in the oro-facial region including head, face and related structures. The aetiology and the pathophysiology of TMD is poorly understood. It is generally accepted that the aetiology is multifactorial, involving a large number of direct and indirect causal factors. Among such factors, occlusion is frequently cited as one of the major aetiological factors causing TMD. It is well known from epidemiologic studies that TMD-related signs and symptoms, particularly temporomandibular joint (TMJ) sounds, are frequently found in children and adolescents and show increased prevalence among subjects between 15 and 45 years old. Aesthetic awareness, the development of new aesthetic orthodontic techniques and the possibility of improving prosthetic rehabilitation has increased the number of adults seeking orthodontic treatment. The shift in patient age also has increased the likelihood of patients presenting with signs and symptoms of TMD. Because orthodontic treatment lasts around 2 years, orthodontic patients may complain about TMD during or after treatment and orthodontists may be blamed for causing TMD by unsatisfied patients. This hypothesis of causality has led to legal problems for dentists and orthodontists. For these reasons, the interest in the relationship between occlusal factors, orthodontic treatment and TMD has grown and many studies have been conducted. Indeed, claims that orthodontic treatment may cause or cure TMD should be supported by good evidence. Hence, the aim of this article is to critically review evidence for a possible association between malocclusion, orthodontic treatment and TMD.

Comparison of occlusal bite force distribution in subjects with different occlusal characteristics

Abstract: To analyze bite force distribution in subjects with different occlusal characteristics. This prospective study included 132 candidates (50 males, 82 females) seeking orthodontic treatment, who were...

Pathogenetic justification of new approaches to the assessment of the state of oral cavity in chronic generalized parodontitis

Abstract: Introduction. A variety of concepts and approaches to the analysis of the etiology and pathogenesis of temporomandibular joint dysfunctions, results in increased interest in the search for highly informative diagnostic methods, especially at the stage of pre-clinical manifestations. Objectives. The aim of the study was to analyze the possibilities of modern technologies in diagnostics of temporomandibular joint dysfunctions. Materials and methods. We studied original papers on the diagnostics of temporomandibular joint dysfunctions from several databases: Russian State Library, eLibrary, PubMed, The Cochrane Library, Google Scholar. Results. The review presents both generally accepted and alternative approaches to the diagnostics of different clinical manifestations in temporomandibular joint dysfunctions. We described the diagnostic value of occlusal disorders analysis in universal articulators, virtual articulators, T-scan system. Capabilities of teleroentgenography, axiography, electromyography, computed and magnetic resonance imaging were estimated as well. Conclusions. The literature review on the problem of diagnosing the temporomandibular joint dysfunctions showed a scientifically based spectrum of diagnostic capabilities of modern dentistry, a trend in the development of highly informative digital diagnostic technologies. Due to the diversity of the etiology and pathogenesis of the temporomandibular joint dysfunctions further in-depth studies of this issue are required.