Oral health in youth with visual impairment: A longitudinal survey.

This longitudinal survey aims to demonstrate improvement in oral hygiene among a group of youth with visual impairment (VI) achieved by repeated oral hygiene training, compare their progress with healthy peers (CG) and assess their oral health knowledge. In 100 VI (55♀, 45♂; ± 17.8 years) and 45 CG (23♀, 22♂; ± 17.2 years) oral hygiene training and a Quigley-Hein Plaque Index (QHI) rating were repeated six times at three-month intervals. The VI were divided into four subgroups according to the toothbrush hardness/type. A questionnaire was given to both groups. Appropriate statistical analyses were performed at 5% significance level. Both groups showed reduction in QHI, the VI had overall higher QHI values than CG. Use of an electric toothbrush in VI led to lower QHI in the last examination (p < 0.03). 69% of participants recommended dental specialists to improve communications by acquiring more illustrative aids. VI changed toothbrush less often (p < 0.02). A higher incidence of dental plaque was confirmed in VI compared to CG. After education and individual training, gradual plaque reduction has occurred in both groups. Using an electric toothbrush in VI resulted in better QHI outcomes. Repetitive preventive intervention in youth with VI helped them to adopt healthier oral hygiene habits.

Diffuse Reflectance Spectroscopy as a Novel Method of Caries Detection-An In Vitro Comparative Study in Permanent Teeth.

This in vitro study aimed to compare outcomes of dental caries detection using visual inspection classified according to the International Caries Detection and Assessment System (ICDAS) with objective assessments using a well-established laser fluorescence system (Diagnodent pen) and a novel diffuse reflectance spectroscopy (DRS) device. One hundred extracted permanent premolars and molars were utilized, including sound teeth, teeth with non-cavitated caries, or teeth with small cavitated lesions. A total of 300 regions of interest (ROIs) were assessed using each detection method. Visual inspection, being a subjective method, was performed by two independent examiners. The presence and extent of caries were histologically verified according to Downer's criteria, serving as a reference for other detection methods. Histological results revealed 180 sound ROIs and 120 carious ROIs, categorized into three different extents of caries. Overall, there was no significant difference between the detection methods in sensitivity (0.90-0.93) and false negative rate (0.05-0.07). However, DRS exhibited superior performance in specificity (0.98), accuracy (0.95), and false positive rate (0.04) compared to other detection methods. Although the tested DRS prototype device exhibited limited penetration depth, it shows promise as a method, particularly for the detection of incipient caries.

Metal hypersensitivity and pro-inflammatory cytokine production in patients with failed orthopedic implants: A case-control study.

Orthopedic implants heal well without complications in most patients but fail for unclear reasons in some individuals. This study determined the relevance of metal hypersensitivity in patients with failed orthopedic implants and those requiring orthopedic implant surgery. The study included 35 patients with failed orthopedic implants and 15 subjects scheduled for orthopedic implant surgery. The production of selected pro-inflammatory cytokines was measured in patients with failed orthopedic implants. Metal hypersensitivity was measured in all subjects using the MELISA® test. Of common metals in orthopedic alloys, the patients with failed orthopedic implants responded most frequently to nickel, chromium, titanium, iron, and molybdenum. Hypersensitivity to metals found in implants was measured in 40% of patients with failed implants. The study also showed that titanium exposure in patients with titanium hypersensitivity might lead to implant failure. Metal hypersensitivity testing should be offered to patients before surgery to minimize the risk of implant failure.

Titanium and Other Metal Hypersensitivity Diagnosed by MELISA® Test: Follow-Up Study.

This study is aimed at proving the clinical benefit of the MELISA® test in the minimization or complete elimination of health problems in patients with confirmed hypersensitivity to metals used for tissue replacements. A group of 305 patients aged 20-75 years with previously proven metal hypersensitivity (initial MELISA® test), mainly to titanium and then to another fifteen metals, was chosen from the database at the Institute of Dental Medicine. From these patients, a final group of 42 patients agreed to participate in the study, 35 of which were female and 7 were male. The patients completed a special questionnaire aimed at information regarding change of health status from their last visit and determining whether the results of the initial MELISA® test and recommendations based on it were beneficial for patients or not. They were clinically examined, and peripheral blood samples were taken to perform follow-up MELISA® tests. Questionnaire data was processed, and the follow-up MELISA® test results were compared with the results of the initial MELISA® tests. For statistical analysis, the Fisher's exact test and paired T-test were used. Thirty-two patients reported that they followed the recommendations based on the results of the initial MELISA® tests, and of these, 30 patients (94%) confirmed significant health improvement. Six patients did not follow the recommendation, and from these, only one patient reported an improvement in his health problems. By comparison of the initial and follow-up MELISA® test results, it can be stated that the hypersensitivity to the given metal decreased or disappeared after the therapeutic interventions performed based on the initial MELISA® test results. The evaluation of the data obtained from patients in this study confirmed a significant clinical benefit of MELISA® test.

Effect of Blood Component Coatings of Enosseal Implants on Proliferation and Synthetic Activity of Human Osteoblasts and Cytokine Production of Peripheral Blood Mononuclear Cells.

The study monitored in vitro early response of connective tissue cells and immunocompetent cells to enosseal implant materials coated by different blood components (serum, activated plasma, and plasma/platelets) to evaluate human osteoblast proliferation and synthetic activity and inflammatory response presented as a cytokine profile of peripheral blood mononuclear cells (PBMCs) under conditions imitating the situation upon implantation. The cells were cultivated on coated Ti-plasma-sprayed (Ti-PS), Ti-etched (Ti-Etch), Ti-hydroxyapatite (Ti-HA), and ZrO2 surfaces. The plasma/platelets coating supported osteoblast proliferation only on osteoconductive Ti-HA and Ti-Etch whereas activated plasma enhanced proliferation on all surfaces. Differentiation (BAP) and IL-8 production remained unchanged or decreased irrespective of the coating and surface; only the serum and plasma/platelets-coated ZrO2 exhibited higher BAP and IL-8 expression. RANKL production increased on serum and activated plasma coatings. PBMCs produced especially cytokines playing role in inflammatory phase of wound healing, that is, IL-6, GRO-α, GRO, ENA-78, IL-8, GM-CSF, EGF, and MCP-1. Cytokine profiles were comparable for all tested surfaces; only ENA-78, IL-8, GM-CSF, and MCP-1 expression depended on materials and coatings. The activated plasma coating led to uniformed surfaces and represented a favorable treatment especially for bioinert Ti-PS and ZrO2 whereas all coatings had no distinctive effect on bioactive Ti-HA and Ti-Etch.

Modeling of load transmission and distribution of deformation energy before and after healing of basal dental implants in the human mandible.

The purpose of this study was to present the amount and distribution of pressure, stress, and deformation energy when basal implants in the mandible are restored with a bridge which is loaded at two different stages of bone healing. The model geometry and material properties of the mandible were gained from CT scans of a human mandible. The material model used in this study defined bone as an inhomogeneous, linear elastic isotropic material. The masseter and temporal muscles were considered as rigid connections between the bones in typical positions and directions. The rotation axis was simulated in the temporomandibular joint. The loading force of 450 N was assumed to be in the middle between the left molar and left canine implant. In freshly operated bone, the total deformation energy is 30% higher than in healed bone, due to the defined energy absorbing soft bone areas. Approximately 90% of the deformation energy is absorbed by the bone, regardless of the healing state of the bone. The immediate rigid implant splinting distributes peak forces. To cope with these energies, the necessity of a reduction of total masticatory forces or the use of additional implants for force distribution should be considered individually.

Influence of metals on cytokines production in connection with successful implantation therapy in dentistry.

OBJECTIVES: In most of patients in need of implantation treatment in the oral cavity, implants heal well, nevertheless, there are some individuals, in whom titanium implants fail for reasons, which remain unclear. DESIGN: The aim of our study was to determine if there is a difference between metal influenced IL-1ß, IL-4, IL-6, TNF-α and IFN-γ cytokines production in patients with successfully healed implants compared to those, whose implant therapy was unsuccessful. SETTING: The two study groups included 12 patients with failed dental titanium implants and 9 patients with successfully healed implants. In the subjects, cytokine production was established after lymphocyte cultivation with mercury, nickel and titanium antigens. RESULTS: IL-1ß levels were significantly increased in all patients after stimulation with titanium and in patients with accepted implants compared to patients with failed implants after the stimulation with mercury and titanium. Titanium caused significantly increased IL-6 production in all patients. TNF-α and IFN-γ levels were also significantly increased after the stimulation with titanium. Significantly increased TNF-α levels were found in patients with accepted implants as compared to patients with failed implants. CONCLUSIONS: Increased production of IL-1ß a IL-6 cytokines in reaction to titanium and increased production of TNF-α and IFN-γ cytokines in reaction to mercury, which is very often present in the form of amalgam in the oral cavity of persons in need of implant therapy, can play an important role in immune reactions during implant healing process. In patients with failed titanium implants, decreased production of these cytokines may participate in implant failure.

Implementation of contact definitions calculated by FEA to describe the healing process of basal implants.

AIMS: Bone structure around basal implants shows a dual healing mode: direct contact areas manifest primary osteonal remodeling, in the void osteotomy-induced spaces, the repair begins with woven bone formation. This woven bone is later converted into osteonal bone. The purpose of this study was to develop a model to accurately represent the interface between bone and basal implant throughout the healing process. The model was applied to the biological scenario of changing load distribution in a basal implant system over time. METHODS: Computations were made through finite element analysis using multiple models with changing boneimplant contact definitions which reflected the dynamic nature of the interface throughout the bony healing process. Five stages of bony healing were calculated taking into account the changes in mineral content of bone in the vicinity of the load transmitting implant surfaces. RESULTS: As the bony integration of basal implants proceeds during healing, peak stresses within the metal structure shift geographically. While bony repair may still weaken osteonal bone, woven bone has already matured. This leads to changes in the load distribution between and within the direct contact areas, and bone areas which make later contact with implant. CONCLUSIONS: This study shows that basal implants undergo an intrinsic shift of maximum stress regions during osseointegration. Fatigue testing methods in the case of basal implants must therefore take into account this gradual shift from early healing phase until full osseointegration is achieved.

The use of finite element analysis to model bone-implant contact with basal implants.

OBJECTIVE: The purpose of this study was to develop a model that accurately represents the interface between bone and basal implants throughout the healing process. STUDY DESIGN: The model was applied to the biological scenario of changing load distribution in a basal implant system over time. We did this through finite element analysis (FEA, or finite element method [FEM]), using multiple models with changing bone-implant contact definitions, which reflected the dynamic nature of the interface throughout the bony healing process. RESULTS: In the simple models, peak von Mises stresses decreased as the bone-implant-contact definition was changed from extremely soft contact (i.e., immature bone during early loading) to hard contact (i.e., mature bone). In upgraded models, which more closely approximate the biological scenario with basal dental implant, peak von Mises stresses decreased at the implant interface; however, they increased at the bone interface as a harder contact definition was modeled. Further, we found a shift in peak stress location within the implants during different contact definitions (i.e., different stages of bony healing). In the case of hard contact, the peak stress occurs above the contact surface, whereas in soft contact, the stress peak occurs in the upper part of the contact area between bone and the vertical shaft of the implant. Only in the extreme soft contact definitions were the peak stresses found near the base plate of the implant. CONCLUSION: Future FEM studies evaluating the functional role of dental implants should consider a similar model that takes into account bone tissue adaptations over time.

Bendable vs. angulated dental implants: consideration of elastic and plastic material properties based on experimental implant material data and FEA.

AIM: Bendable and angulated single-piece implants are used alternatively to screwable abutments in two-piece dental implant designs. Though used frequently, data on the stress distribution within such implants are not available and the question whether the bending contributes to fracture resistance has not been addressed. METHODS: We used the method of finite element to identify von Mises stresses and maximum stresses in bent and non-bent but angulated implants. Implants with one (e.g. applicable to screw designs) or two (applicable to basal implants) bending areas were the variables under investigation. RESULTS: For bends up to 13 degrees we discovered that if there is only one bend, the maximum stress is in the bent area. If two bends are made in two different bending areas, the maximum stresses are distributed between the two and, if either one of the bent areas is machined, there are no residual stresses within the implant body in this area. The maximum stresses are always located near the base-plates. The absolute value of the maximum stress is higher because no residual stresses are available to compensate stresses that stem from loading. CONCLUSION: Assuming that all other parameters are equal, bendable (basal) implants show a more even stress distribution along the vertical implant region than identically shaped implants with a machine-angulated area. Bendable basal implants therefore probably resist masticatory forces better than pre-angulated, machined implants, and unbent implants which provide a thin region in the vertical implant area.

Time analysis of hard and soft bolus processing.

OBJECTIVE: Clinical observations and mathematical models show that dental implants are influenced by the magnitude of loading. Therefore, the knowledge of mandible movement during mastication is important to assess occlusal and masticatory force vectors. The purpose of this study was to detect the path of movement of the lower jaw and to distinguish stages of mastication, duration of bolus processing and peak amplitude of mastication. METHOD: Motion analysis was used to record three-dimensional mandible movements. Individualized sensors were rigidly attached to the mandible of 51 study participants. At the beginning of the measurement, all subjects were asked to move the mandible in extreme positions (maximal opening and maximal lateral movements). Then, each subject masticated a bite of hard and soft food. Duration of bolus mastication and peak amplitude of mastication movement in mesio-distal, cranio-caudal and vestibulo-oral axes related to peak amplitude of marginal movements were evaluated for each subject. The chewing record of each subject was divided into three phases (chopping, grinding and swallowing), and the duration of mastication and number of closing movements were evaluated. RESULTS: The findings of this pilot study suggest that masticatory movements vary in individuals. Bolus character influences the process duration, but not the frequency of closing movements. Neither gender nor age had any influence on either the time or frequency of bolus processing. CONCLUSION: Relationships to directions and magnitudes of acting chewing force should be more precisely examined since transversally acted forces during grinding are important factors in tooth/implant overloading.

Influence of implant length and diameter on stress distribution: a finite element analysis.

STATEMENT OF PROBLEM: Masticatory forces acting on dental implants can result in undesirable stress in adjacent bone, which in turn can cause bone defects and the eventual failure of implants. PURPOSE: A mathematical simulation of stress distribution around implants was used to determine which length and diameter of implants would be best to dissipate stress. MATERIAL AND METHODS: Computations of stress arising in the implant bed were made with finite element analysis, using 3-dimensional computer models. The models simulated implants placed in vertical positions in the molar region of the mandible. A model simulating an implant with a diameter of 3.6 mm and lengths of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 17 mm, and 18 mm was developed to investigate the influence of the length factor. The influence of different diameters was modeled using implants with a length of 12 mm and diameters of 2.9 mm, 3.6 mm, 4.2 mm, 5.0 mm, 5.5 mm, 6.0 mm, and 6.5 mm. The masticatory load was simulated using an average masticatory force in a natural direction, oblique to the occlusal plane. Values of von Mises equivalent stress at the implant-bone interface were computed using the finite element analysis for all variations. Values for the 3 most stressed elements of each variation were averaged and expressed in percent of values computed for reference (100%), which was the stress magnitude for the implant with a length of 12 mm and diameter of 3.6 mm. RESULTS: Maximum stress areas were located around the implant neck. The decrease in stress was the greatest (31.5%) for implants with a diameter ranging from of 3.6 mm to 4.2 mm. Further stress reduction for the 5.0-mm implant was only 16.4%. An increase in the implant length also led to a decrease in the maximum von Mises equivalent stress values; the influence of implant length, however, was not as pronounced as that of implant diameter. CONCLUSIONS: Within the limitations of this study, an increase in the implant diameter decreased the maximum von Mises equivalent stress around the implant neck more than an increase in the implant length, as a result of a more favorable distribution of the simulated masticatory forces applied in this study.

Influence of galvanic phenomena on the occurrence of algic symptoms in the mouth.

The presence of more than one dental alloy in the oral cavity often causes pathological galvanic currents and voltage. Due to various and multi-faceted symptomathology, they tend to be a source of significant problems not only for the patient but also for the attending dentist. Very discreet and uncharacteristically objective diagnosis during a regular examination frequently causes this state to be ascribed to a completely different illness.