Davor Illeš

Bio: Davor Illeš is an academic researcher from University of Zagreb. The author has contributed to research in topics: Electromyography & Temporal muscle. The author has an hindex of 7, co-authored 27 publications receiving 191 citations.

Dental archforms in dentoalveolar Class I, II and III

Abstract: Objective: To test the hypothesis that no differences exist in dental arch dimensions between dentoalveolar Classes I, II, and III, and between male and female subjects, as measured on virtual three-dimensional (3D) models. Materials and Methods: Samples included randomly selected plaster dental casts of 137 white patients (43 Class I, 50 Class II, and 44 Class III) from the Department of Orthodontics, School of Dental Medicine, University of Zagreb, Croatia. Dental models were scanned and digitized using ATOS II SO (“Small Objects”) scanning technology (GOM mbH, Braunschweig, Germany). Eight linear and two proportional measurements were calculated for both upper and lower dental arches. Results: In men, a significant difference in the upper dental arch was present in the incisor region, and in the lower dental arch, differences were found in intercanine and intermolar widths (P < .05). Significant differences were noted between male groups in the upper molar depth dimension (P = .022) and in t...

The influence of dental status on masticatory muscle activity in elderly patients.

Abstract: Aims. The objective of this study was to determine whether the elevator and depressor muscle activity during five minutes mastication is affected by the presence of the prosthetic appliance in eld erly patients. Methods. Thirty edentulous subjects (EG) and 30 age-matched dentate subjects (DG) were studied. Surface electromyographic (EMG) recordings were obtained from the anterior temporal muscle (T), masseter muscle (M) and from the submandibular group in the region of the anterior belly of the digastrics muscle (D) on the left (L) and right (R) side. Muscle activity was registrated during maximal voluntary contraction (MVC) at the intercuspal position, maximal opening (Omax), and during five minutes of mastication. Elevator muscle activity during mastication was expressed in percentages of the maximal muscle activity in intercuspal position and depressor muscle activity was expressed in percentages of maximum opening. By using mixed ANOVA design, the effect of three factors was investigated: the factor of muscle with six muscles involved, the factor of time (five minutes of mastication), and the factor of dental status where some participants had their own natural dentition whereas others had complete dentures. Results. The results revealed significant effects of factors muscle and time (pP<0.001 for factor "muscle" pP<0.001 for factor "time"). The muscle was not significant by group interaction (p=0, 254), whileThe time by group interaction was significant (pP=0, .046). In EG muscle activity gradually decreased during the whole five minute interval of mastication, while in DG it decreased more rapidly from the 1st to the 3rd minute and then it increased till the 5th minute. There was also a significant effect regarding the presence of natural teeth or complete dentures (pP<0.034). Complete denture wearers had higher muscle activity relatively to % of MVC or % of Omax than dentate subjects. Conclusions. Muscle activity during five minutes of mastication depends greatly of the presence of the prosthetic appliance, since edentulous subjects had to use higher potentials of muscle activity (% of MVC or % of Omax) than age matched dentate subjects and were unable to increase activity at the end of mastication. The difference in chewing patterns and activity between complete denture wearers and dentate subjects should be explained to the patients prior to the prosthetic treatment in order to put their expectations into right perspective.

Influence of occlusal stabilization splint on the asymmetric activity of masticatory muscles in patients with temporomandibular dysfunction.

Abstract: The aim of present study was to evaluate the symmetry of masticatory muscles' activity at various clenching levels in the intercuspal position in patients with functional disorders and in healthy subjects. The purpose was also to determine the effect of full-arch maxillary stabilization splint on the asymmetry of masticatory muscle activity in patients with temporomandibular dysfunction. In this study 6 TMD patients and 12 healthy subjects were investigated. Surface EMG recordings were obtained from left and right anterior temporal, left and right masseter and from the sub-mandibular group in the region of the anterior belly of the digastric muscle on the left and right side during clenching with the maximum 100% voluntary contraction (MVC) as well as during clenching at 50% and 25% of the maximum activity in the position of maximal intercuspation of teeth. In order to quantify asymmetrical masticatory muscle activity, the asymmetry index (AI) was calculated for each subject and for each muscle from the average anterior temporal, masseter and digastric potentials recorded during each test (100% MVC, 50% MVC and 25% MVC). In the group of patients EMG recordings were repeated during and after the splint therapy. The asymmetries of masticatory muscle activity was present in both groups, but in the group of TMD patients the asymmetry indices for anterior temporal muscle at 100% MVC (p = 0.049) and 50% MVC (p = 0.031) were significantly higher. Results have shown that the use of splint suppressed the asymmetry of all muscles, as during the splint therapy the asymmetry indices were lowered. After the therapy, the level of temporal muscle symmetry during submaximal clenching in the intercuspal position increased significantly (p = 0.046). This investigation points out that electromyography may be a valuable method of documenting that asymmetric activity of masticatory muscles improves after occlusal splint therapy in patients with TMD.

Within-Subject Reliability and between-Subject Variability of Oxidative Stress Markers in Saliva of Healthy Subjects: A Longitudinal Pilot Study.

Abstract: The present study evaluated diurnal variations and day-to-day fluctuations of salivary oxidative stress (OS) markers in healthy adult individuals. Whole unstimulated saliva was collected at 2 time intervals over 3 consecutive days. Glutathione peroxidase (GPX), superoxide dismutase (SOD), total antioxidant capacity (TAC), and uric acid (UA) were analyzed using spectrophotometric methods, while 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) were determined using immunoassays. No significant differences for salivary OS markers between men and women were observed. For all examined OS markers, no significant day-to-day variations were demonstrated. Significant diurnal variations were found in salivary GPX, TAC and MDA levels. For SOD, TAC, GPX, and UA, good-to-moderate intraindividual coefficients of variations (CVs) were observed in more than 75% of the subjects. For MDA and 8-OHdG, intraindividual CVs > 35% were observed in 60% and 40% of the subjects, respectively. Between-subject variance was wide for all examined OS markers (CV% 30.08%–85.70%). Due to high intraindividual variability in the salivary concentrations of MDA and 8-OHdG, those markers cannot be reliably verified based on single measurements and multiple measurements over several days would provide more reliable information. Salivary SOD, TAC, GPX, and UA proved stable across three days of measurement. Trial Registration. ClinicalTrials.gov NCT03029494. Registered on 2017-01-19.

Effect of Clinical Experience on the Shade Matching Accuracy in Different Dental Occupational Groups.

Abstract: Objectives The aim of this study was to evaluate the effect of clinical experience level on the shade matching accuracy in different dental occupational groups. Materials and methods A total of 80 participants, assigned to one of four groups depending on the level of their clinical experience in shade matching: dental technicians (DTs), residents in prosthodontics (RPs), specialists in prosthodontics (SPs) and dental students (DSs) took part in the study. They were asked to use Tooth guide Training Box (TTB) and determine 15 standardized shade tabs using VITA 3D-Master shade guide. The number of mistakes in final test for each participant was recorded and accuracy was calculated. Color difference (ΔE) values for each shade were calculated from L*, a* and b* values. Differences in accuracy, mean ΔE values and mean error ΔE values between four different groups were examined. Results No statistically significant differences were found between the groups regarding accuracy and mean ΔE values (p>0.05). The accuracy rate in four groups was 0.51±0.20 (DTs), 0,54±0.18 (RPs), 0.49±0.16 (SPs) and 0.55±0.14 (DSs), respectively. Mean ΔE values were 2.10±0.98 (DTs), 2.18±0.97 (RPs), 2.51±0.97 (SPs) and 2.08±0.86 (DSs), respectively. Regarding mean error ΔE values, DTs made errors with significantly less deviations compared to other groups (p<0.05). Conclusions This study has shown that clinical experience is not found to be a significant factor to the shade matching accuracy. With regard to the mean error ΔE values, DTs were more successful in shade matching than other participants.

Otologic symptoms of temporomandibular disorder and effect of orofacial myofunctional therapy.

Abstract: The aim of this study was to investigate the frequency of otologic symptoms and their relationship to orofacial signs and symptoms of temporomandibular disorder (TMD), and the effect of orofacial myofunctional therapy. The study was conducted on eight asymptomatic subjects (Group C) and 20 subjects with articular TMD, randomly distributed over two groups: one treated using orofacial myofunctional therapy (OMT Group) and a control group with TMD (Group CTMD). Patient selection was based upon the Research Diagnostic Criteria for TMD (RDC/TMD). All subjects submitted to a clinical examination with self-reporting of symptom severity, and to orofacial myofunctional and electromyographic evaluation at diagnosis and again, at the end of the study. Correlations were calculated using the Pearson test and inter- and intragroup comparisons were made (p < 0.05). In the diagnosis phase, subjects with TMD reported earache (65%), tinnitus (60%), ear fullness (90%), and 25% of the asymptomatic subjects reported tinnitus. The otologic symptoms were correlated with tenderness to palpation of the temporomandibular muscles and joints and with orofacial symptoms. Only the OMT group showed a reduction of otologic and orofacial symptoms, of tenderness to palpation and of the asymmetric index between muscles. OMT may help with muscle coordination and a remission of TMD symptoms.

The adaptive response of jaw muscles to varying functional demands

Abstract: Jaw muscles are versatile entities that are able to adapt their anatomical characteristics, such as size, cross-sectional area, and fibre properties, to altered functional demands. The dynamic nature of muscle fibres allows them to change their phenotype to optimize the required contractile function while minimizing energy use. Changes in these anatomical parameters are associated with changes in neuromuscular activity as the pattern of muscle activation by the central nervous system plays an important role in the modulation of muscle properties. This review summarizes the adaptive response of jaw muscles to various stimuli or perturbations in the orofacial system and addresses general changes in muscles as they adapt, specific adaptive changes in jaw muscles under various physiologic and pathologic conditions, and their adaptive response to non-surgical and surgical therapeutic interventions. Although the jaw muscles are used concertedly in the masticatory system, their adaptive changes are not always uniform and vary with the nature, intensity, and duration of the stimulus. In general, stretch, increases neuromuscular activity, and resistance training result in hypertrophy, elicits increases in mitochondrial content and cross-sectional area of the fibres, and may change the fibre-type composition of the muscle towards a larger percentage of slow-type fibres. In contrast, changes in the opposite direction occur when neuromuscular activity is reduced, the muscle is immobilized in a shortened position, or paralysed. The broad range of stimuli that affect the properties of jaw muscles might help explain the large variability in the anatomical and physiological characteristics found among individuals, muscles, and muscle portions.

Electromyographic standardized indices in healthy Brazilian young adults and data reproducibility.

Abstract: The determination of normal parameters is an important procedure in the evaluation of the stomatognathic system. We used the surface electromyography standardization protocol described by Ferrario et al. (J Oral Rehabil. 2000;27:33-40, 2006;33:341) to determine reference values of the electromyographic standardized indices for the assessment of muscular symmetry (left and right side, percentage overlapping coefficient, POC), potential lateral displacing components (unbalanced contractile activities of contralateral masseter and temporalis muscles, TC), relative activity (most prevalent pair of masticatory muscles, ATTIV) and total activity (integrated areas of the electromyographic potentials over time, IMPACT) in healthy Brazilian young adults, and the relevant data reproducibility. Electromyography of the right and left masseter and temporalis muscles was performed during maximum teeth clenching in 20 healthy subjects (10 women and 10 men, mean age 23 years, s.d. 3), free from periodontal problems, temporomandibular disorders, oro-facial myofunctional disorder, and with full permanent dentition (28 teeth at least). Data reproducibility was computed for 75% of the sample. The values obtained were POC Temporal (88.11 +/- 1.45%), POC masseter (87.11 +/- 1.60%), TC (8.79 +/- 1.20%), ATTIV (-0.33 +/- 9.65%) and IMPACT (110.40 +/- 23.69 microV/microV.s %). There were no statistical differences between test and retest values (P > 0.05). The Technical Errors of Measurement (TEM) for 50% of subjects assessed during the same session were 1.5, 1.39, 1.06, 3.83 and 10.04. For 25% of the subjects assessed after a 6-month interval, the TEM were 0.80, 1.03, 0.73, 12.70 and 19.10. For all indices, there was good reproducibility. These electromyographic indices could be used in the assessment of patients with stomatognathic dysfunction.

Online learning in dentistry: an overview of the future direction for dental education.

Abstract: This paper provides an overview of the diversity of tools available for online learning and identifies the drivers of online learning and directives for future research relating to online learning in dentistry After an introduction and definitions of online learning, this paper considers the democracy of knowledge and tools and systems that have democratized knowledge It identifies assessment systems and the challenges of online learning This paper also identifies the drivers for online learning, including those for instructors, administrators and leaders, technology innovators, information and communications technology personnel, global dental associations and government A consideration of the attitudes of the stakeholders and how they might work together follows, using the example of the unique achievement of the successful collaboration between the Universities of Adelaide, Australia and Sharjah, United Arab Emirates The importance of the interaction of educational principles and research on online learning is discussed The paper ends with final reflections and conclusions, advocating readers to move forward in adopting online learning as a solution to the increasing worldwide shortage of clinical academics to teach dental clinicians of the future