A revised approach of human mastication function rehabilitation through monotypical mastication analysis.

OBJECTIVE: The aim of the simulation was to find the forcing laws, which provide the close-to reality mastication motions of the components of the system and to investigate the contact zones, interaction forces and their action points as they vary in time. The loss of one or few elements of the mastication system can be restored without significant violations of the overall function provided the general correlations among the mastication system elements, which were influenced during the evolutionary development, have been determined in advance. MATERIALS AND METHODS: We present an approach based on the computer simulation of mastication biomechanics on the basis of finite element (FE) models. They were generated by using the data acquired with both optical and CT scanning systems, which enabled to obtain highly accurate three-dimensional geometrical models of all hard parts of the mastication system of a real dead goat. The surfaces of dental arcs of upper and lower jaws mechanically interacting one against another have been used as the main parts of the model. RESULTS: Using FE models we discovered that mastication forces are correlated directly between dental arches and TMJ surfaces. Factors influencing geometry of dental arches results a destroy jaw function. CONCLUSION: In the course of this analysis the mastication system of a goat has been considered as a representative of the ruminant individual and enabled to demonstrate the mechanics of the mastication process with insights for evaluation of the similarities and differences against the human mastication.

The relationship between unilateral mandibular angle fracture and temporomandibular joint function.

PURPOSE. Aim of this study was to analyze relation of occlusal correction and alterations of temporomandibular joint function during treatment of unilateral mandibular fractures. MATERIALS AND METHODS. We compared 49 patients treated for unilateral mandibular fracture without occlusal correction with 21 patient treated for unilateral mandibular fracture along with early and consequent occlusal analysis and correction and with 49 control subjects. Patients' complaints, mandibular movements and occlusal parameters were evaluated during the period of healing. ZEBRIS ultrasound system (Jaw Motion Analyzer, Zebris Medical GmbH, Isny, Germany) was used for analysis of mandibular movements and T-Scan analyzer (Tekscan, Inc., Boston, MA, USA) was used for occlusal analysis. RESULTS. Findings of our study showed statistically significant (p<0.05) diminution of patients complaints, mandibular movement alterations and occlusal disturbances in patients who received occlusal correction during MF treatment if compared to patients treated without occlusal correction, except noises from the joint in the injured side and mandibular lateral track to the injured side in the final stage of investigation. Despite applied treatment recovery of the TMJ function was not complete and the investigated parameters remained worse if compared to the control group. CONCLUSIONS. Results of this study confirmed positive influence of early and subsequent occlusal analysis and correction during stages of MF treatment on diminution of functional alterations of the temporomandibular joint function. Timely occlusal correction improves and hastens process of rehabilitation therefore it is indispensable part of MF treatment.

Dynamical changes of occlusion and articulation during treatment of mandibular angle fractures.

Outcomes of mandibular fractures were stated as frequent reason of temporomandibular joint dysfunctions. The objective of this study was to evaluate dynamical changes of occlusion and articulation during treatment of mandibular angle fractures. 12 subjects with mandibular angle fractures underwent analysis of occlusion and articulation in all stages of healing. Findings of investigations were presented in Posselt's and intercondylar axis diagrams, occlusiograms and relative force vs. time graphs. Comparison of results in first day, 1, 3 and 6 months after trauma showed that despite typical process of fragments healing and good fixation but with insufficiently balanced occlusion and posttraumatic discoordination of muscle activity first signs of TMJ articular discs dysfunction were found. Our results confirm the concept that early rehabilitation of mandibular function and occlusion are essential to prevent developing functional disorders of TMJ.

Activity of neutrophil ß-glucuronidase in diabetic and nondiabetic patients with chronic generalized periodontitis and healthy subjects.

OBJECTIVE. The aim of the study was to establish the dynamics of ß-glucuronidase activity in subjects suffering from type 1 diabetes and chronic untreated generalized periodontitis, subjects suffering from chronic untreated generalized periodontitis only, and control subjects not suffering from generic diseases with healthy periodontal tissue. MATERIAL AND METHODS. The study involved 165 19-50-year-old subjects who were divided into three groups: healthy subjects (n=55), subjects with chronic untreated generalized periodontitis (n=55), and subjects with type 1 diabetes and chronic untreated generalized periodontitis (n=55). Neutrophilic leukocytes of peripheral venous blood were exposed to bacterial stimuli: opsonized zymosan, nonopsonized Staphylococcus aureus, and prodigiosan. The activity of ß-glucuronidase was determined by the spectrofluorimetry method. RESULTS. The diagnostic value of changes in ß-glucuronidase activity of neutrophilic leukocytes markedly increased in all study groups after stimulation of neutrophilic leukocytes by opsonized zymosan, nonopsonized Staphylococcus aureus, and prodigiosan as compared to control media not exposed to any stimulus (P<0.001). The strongest relationship (canonical correlation coefficient eta, 0.993) between the intensity of periodontal pathology markers and the activity of ß-glucuronidase of neutrophilic leukocytes in incubated media in patients with type 1 diabetes mellitus and periodontitis was found under the effect of nonopsonized Staphylococcus aureus. CONCLUSIONS. If periodontal impairment is severe, diabetes mellitus possibly causes a faster destruction of the periodontal tissue and presents a higher risk of periodontitis for patients with diabetes.

Lysozyme and microbiota in relation to gingivitis and periodontitis.

BACKGROUND: The aim of this study was to investigate associations between the immune component of the oral cavity, lysozyme, in gingival crevicular fluid and unstimulated saliva, and colonization dynamics of periodontopathogenic bacteria from supra- and subgingival plaque samples in patients with gingivitis or periodontitis. MATERIAL/METHODS: Lysozyme in crevicular fluid and unstimulated saliva, and bacteria in supra- and subgingival plaque samples were assessed in 84 samples from 28 patients with gingivitis, 96 samples from 32 patients with periodontitis, and 72 samples from 24 donors with intact periodontium and free of internal disease. Lysozyme activity was determined spectrophotometrically. The micro-IDent plus assay was used to detect 6 periodontopathogenic bacteria plaque samples. RESULTS: Lysozyme activity in crevicular fluid in the gingivitis and periodontitis groups was significantly greater than that in the donor group, but lysozyme activity in unstimulated saliva was less than that in the donor group. Peptostreptococcus micros, Fusobacterium periodontium and Campylobacter rectus were predominant in subgingival plaque samples in the periodontitis group compared to the donor group (P<0.001), and Eubacterium nodatum and Eikenella corrodens were predominant in the gingivitis group compared to the donor group (P<0.001). CONCLUSIONS: Lysozyme activity in crevicular fluid and in unstimulated saliva correlated with periodontal pocket depth in donors and in patients with gingivitis or periodontitis (specificity and sensitivity were both 100%). These findings indicate that infection with P. micros, F. periodontium, E. nodatum, E. corrodens, and C. rectus may be an important indicator of inflammatory periodontal disease development.

[Microbiological and biochemical characteristics of inflammatory tissues in the periodontium]. / Uzdegiminiu apydancio audiniu mikrobiologines ir biochemines savybes.

OBJECTIVE: To investigate bacterial populations in subgingival and supragingival plaque samples of patients with inflammatory periodontal diseases and activities of the lysosomal enzymes--lysozyme, alkaline phosphatase, and beta-glucuronidase--in peripheral venous blood, in gingival crevicular fluid, and mixed nonstimulated saliva. METHODS AND MATERIALS: The study included 60 patients with inflammatory periodontal diseases without any internal pathology and 24 periodontally healthy subjects. Molecular genetic assay (Micro-IDent plus, Germany) for complex identification of additional six periodontopathic bacteria was applied. The activity of lysozyme was determined turbidimetrically, the activity of alkaline phosphatase--spectrophotometrically with a "Monarch" biochemical analyzer, the activity beta-glucuronidase--according to the method described by Mead et al. and modified by Strachunskii. RESULTS: A statistically significant association between clinical and bacteriological data was found in the following cases: gingival bleeding in the presence of Eubacterium nodatum, Eikenella corrodens, Capnocytophaga spp. (P<0.01); pathological periodontal pockets in the presence of Peptostreptococcus micros (alpha< or =0.05 and beta< or =0.2), Fusobacterium nucleatum (alpha< or =0.05 and beta< or =0.2), Campylobacter rectus (alpha< or =0.05 and beta< or =0.2), and Capnocytophaga spp. (P<0.05); and satisfactory oral hygiene in the presence of all microorganisms investigated (P<0.05). The activity of lysozyme in gingival crevicular fluid and mixed nonstimulated saliva indicates the severity of periodontal inflammation. Based on clinical data, in assessing the amount of lysozyme in mixed nonstimulated saliva, sensitivity and specificity of 100% was found. Increased activities of lysozyme, alkaline phosphatase, and beta-glucuronidase were found in peripheral venous blood of patients with inflammatory periodontal disease as compared to control group. CONCLUSIONS: The main principles of the treatment of periodontal inflammatory diseases should be based on microorganism elimination, creation of individual treatment means affecting microflora in the mouth and immune system of macroorganisms.

A three-dimensional model of the human masticatory system, including the mandible, the dentition and the temporomandibular joints.

The objective of this study was to create a three-dimensional mathematical model of a human masticatory system, including the mandible, the dentition and the temporomandibular joints. Object of research was one 20 year old dead man. The research was approved by Committee of bioethics (Kaunas University of Medicine). Required extent of computed tomography scanning and required high amount and high resolution of images increased X-ray radiation for the object and made this research impossible to perform on alive human. Spiral computed tomography scanning was performed to achieve two-dimensional images, necessary for creating three-dimensional model. The 3D modeling was done using the "Image pro plus" and "Imageware"software. A three-dimensional physiological (normal) model of a human masticatory system, simulating the mandible, the dentition and the temporomandibular joints was generated. This model system will be used subsequently in stress analysis comparison for the physiological and pathological systems after improvement of its physical properties. We suggest that computer simulation is a promising way to study musculoskeletal biomechanics of masticatory system.

Finite element analysis of stresses in the maxillary and mandibular dental arches and TMJ articular discs during clenching into maximum intercuspation, anterior and unilateral posterior occlusion.

The objective of this study was to investigate distribution of stresses in the human TMJ discs, generated during clenching into various occlusal positions. The work presents a biomechanical finite element model of interaction of mandibular and maxillary dental arches and the TMJ discs of a particular person, based on real geometrical data obtained from spiral computed tomography two-dimensional images. 3D contour coordinates - point clouds were collected from these images and solid model was created. The system under investigation consisted of eight basic parts: two rigid structures representing the mandibular and maxillary dental arches, two mandibular condyles, two mandibular fossae of temporal bone, and solid models of two articular discs. The model of maxillary dental arch was fixed in space. The model of the mandibular dental arch was able to move in space synchronically with the mandibular condyles under action of applied forces, which were considered as prescribed and known at insertion points of masticatory muscles. The motion of the mandible was constrained by interdental contact interactions and contact interaction with articular discs, which were situated in between mandibular condyles and mandibular fossae of temporal bone. The model was implemented by using LS-DYNA finite element software. The obtained results presented a 3D view of stresses exhibited in the articular discs, as well as the real contact points of dental interactions at given masticatory geometry of a particular subject and the values of interaction forces. The expected practical value of the developed model is the facilitation of biomechanical evaluations of the influence of tolerances of teeth shapes and occlusal areas together with the supporting areas on the final stress distribution in the dental arches and articular discs.

Secretory function of neutrophilic leukocytes of the patients with periodontal diseases.

Aim of study was to examine periodontal status among 20 44 year old patients and to study the secretory function of peripheral venous blood neutrophilic leukocytes (NL) exposed to various antigens and alkaline phosphatase (AP) activity in gingival crevicular fluid (GCF) in patients suffering from gingivitis and periodontitis. Clinically were determined Russell's periodontal index (PI). Secretory function of NL affected by opsonized zymosane, non-opsonized E. coli was examined in 77 patients with gingivitis and periodontitis, and in 35 donors, free of internal diseases, by means of beta-glucuronidase (beta-GD), lysozyme (LZ). NL secreted higher levels of beta-GD in incubation medium in patients with periodontitis (p < or = 0.001) subject to degree of periodontal lesion. NL affected by various antigens secreted higher levels of LZ into non-cellular matrix in patients with gingivitis and periodontitis comparing to control environment in analogous groups. Data obtained from this study suggest that in patients with periodontitis response of NL to bacterial stimuli is specific and subject to the degree of periodontal lesion. Our study showed a significant difference of AP activity in GCF subject to pocket depth and degree of periodontal lesion. Once NL are exposed to corpuscules prone to phagocytosis, an increase in secretion of beta-GD and LZ can be explained by overall increase in secretion of NL lysosomic enzymes, thus disclosing the mechanism of inflammatory periodontal tissue damage.

Effectiveness evaluation of different suction systems.

Microorganisms of the patient's oral cavity and his/her blood and saliva may cause different air-borne and blood-borne infectious diseases among odontologists and their assistants who work with patients. Quantitative analysis and spatial distribution analysis of the environmental spread of oral liquid and cooling liquid mixture were performed during this study. Effectiveness of suction systems of four types was evaluated: without suction, using a small-size suction pump alone, using a small-size and large-size suction pumps, using a small-size suction pump together with an experimental extra-oral aspirator. Quantitative changes of the water aerosol, which enters the environment during the preparation of teeth, were determined in respect of the used suction systems. The small-size pump system together with an experimental extra-oral suction system eliminated best the aerosol formed during the preparation.