Analysis of dental supportive structures in orthodontic therapy.

The purpose was to define the impact of orthodontic appliances on the density of the underlying dental bone tissue. Radiographic images of teeth were made in 27 study subjects before and twelve months after fixed orthodontic appliances were carried. The radiographs were digitalized and the levels of gray at sites where the greatest bone resorption was expected were transformed into optic density. In the standardization and comparison of values from the first and the second measurements the copper calibration wedge--a stepwedge--was used. Optic densities in the observed sites were compared with optic densities of the calibration wedge and expressed as their thickness equivalent. The study results showed no statistically significant difference in bone densities, indicating that the orthodontic therapy was properly planned and carried out and that excessive forces were not used in the applied correctional procedures.

[Relationship between osteonecrosis of the jaw and bisphosphonate treatment]. / Povezanost osteonekroze celjusti i terapije bisfosfonatima.

Bisphosphonate treatment and its aetiopathogenic association with aseptic osteonecrosis of the jaw is one of the more prominent public health issues today. The aim of this review is to see into the mechanisms of bisphosphonate effects on bones described in literature (anti-osteoclastic activity, cytotoxicity, antiangiogenesis, genetic factors, and imbalance between osteoclasts and osteoblasts). Bisphosphonate treatment is the dominant cause of jaw necrosis. Epidemiological data show an exclusive incidence of osteonecrosis of the jaw in patients who took one or a combination of nitrogen-containing bisphosphonates. Risk factors vary by the bisphosphonate potency (particularly risky are the highly potent pamidronate and zoledronate, which are given intravenously), dosage, duration of treatment, and the illness. Jaw necrosis is most common in oncology patients, and only 5 % in patients with osteoporosis. From a dental-medical point of view, a good oral health is important because osteonecrosis often appears after a periodontal or oral surgical procedure.

Magnetic resonance imaging study on temporomandibular joint morphology.

Magnetic resonance imaging (MRI) has enabled the accomplishment of a more effective diagnostics of temporomandibular disorders (TMD). The sample included 40 patients with clinical symptoms of disc displacement (DD) of temporomandibular joint (TMJ) and 25 subjects included in our study were asymptomatic. DD were diagnosed by clinical examinations which were subsequently confirmed by MRI. DD was found in 18% of the TMJs of the asymptomatic patients. The highest prevalence of total DD without reduction was found in 44.1% of the patients' joints subsequently followed by total DD with reduction comprising 34.9% of the TMJs and by partial DD with reduction comprising 21% of the TMJs. This study may help us clarify the complicated relationship which exists between the radiographic and clinical findings of TMJ disorders.

Dose- and mode-dependent effect of halogen dental curing blue light on the V79-cell line.

The aim of this study was to evaluate the time and dose dependent effect of halogen light from dental curing unit on the cell viability, colony-forming ability and proliferation of the V79 cell culture. The investigation included the medium mode (M), exponential (E) and standard (S) illumination mode for 20, 40 and 80 seconds. The viability was determined using the trypan blue exclusion test. Colony forming ability was assessed by colony count on post-exposure day 7. Cell proliferation was determined by cell counts during five post-exposure days. The viability of cells was not affected by blue light in view of exposure time and modes. Colony forming ability in treated cells was slightly, but not significantly lower than in control cells. Cell proliferation was lower in cells exposed to the M mode for 80 s on post-exposure day 3 and 4 (p < 0.05). On the same post-exposure days, the proliferation of cells exposed to modes E and S, showed a significant inhibition after 20, 40 and 80 s of exposure (p < 0.05). Disrupted cellular functionality and no significant decrease in colony forming ability of V79 cells in addition to time- and dose dependent significant inhibition of cell proliferation might be ascribed to the photocuring blue light activity and/or changes in temperature during the course of experiment in vitro.

Occlusion in patients with temporomandibular joint anterior disk displacement.

The aim of this study was to determine the correlation between the static and dynamic occlusal factors in patients with anterior disk displacement (DD) and to compare it with occlusion in asymptomatic individuals. The study included a group of 40 patients with DD (median age 35.5) and a control group of 25 students of dental medicine (median age 23.4). In all subjects, the position, i.e. DD was determined by magnetic resonance imaging of temporomandibular joints. The study was focused on data gathered by direct analysis of occlusion: relationship between the molars (Angle class), horizontal and vertical overlap, preservation of occlusal contacts between the molars (Eichner classification), difference between contact points in maximal intercuspidation and centric position, and contact points on the laterotrusive and mediotrusive side. There was a statistically significant difference in tooth contact in maximal intercuspidation and centric positions between patients and asymptomatic subjects (p < 0.0001). There was also a difference between occlusal contact points on the mediotrusive side (p < 0.05) since the hyperbalanced contacts were only determined in asymptomatic subjects. Study results support the fact that a number of occlusal factors are related to DD. The fact that hyperbalanced contacts were only determined in asymptomatic subjects suggests that their mutual etiopathogenetic correlation is not quite clear.

[Caries in Croatian Army recruits in 2000]. / Karijes novaka Hrvatske vojske u 2000. Godini.

AIM: The aim of this study was to evaluate oral health of Croatian army recruits, and subsequently, by DMFT index and FST index, to point to dental status of each recruit and to make the diagnosis and treatment plan accordingly. PATIENTS AND METHODS: A total of 248 randomly chosen Croatian Army recruits aged 19-29 underwent examination at a dental office in Koprivnica barracks. Their oral health status was clinically observed and evaluated by use of DMFT and FST indexes. The quality of dental treatment and number of restorations were estimated according to the formula: FTx100/DFT. The study included recruits who had no decayed teeth (DMFT=0), and all teeth, apart from wisdom teeth, were examined. The subjects were divided according to age and place of residence (urban, rural), all of them living in central Croatian counties. They were also interviewed about their dietary habits, and personal oral and dental care. The methods of nonparameter statistics were used due to abnormal data distribution. RESULTS: Healthy teeth were found in 4% of study subjects. The median value of DMFT was 6, and of FST index 25. There were no statistically significant differences in the indices according to either residence or age of recruits. A statistically significant difference was recorded between DT and FST index (p<0.05) according to educational level and understanding of the dietary role of carbohydrates reflected in caries development. Restorations were present in 18.6% of the recruits, i. e. their teeth were well treated, without any further carious lesions. DISCUSSION: The results of epidemiological studies, carried out in many countries, have revealed a decreased number of caries resulting from overall preventive measures that were taken from early childhood. Specific socioeconomic factors play an important role in Croatia as well as in other transition countries. CONCLUSION: The values of DMFT indexes recorded in recruits from other countries tend to be considerably lower than those in Croatian Army recruits. In populations with a high caries incidence it is more appropriate to use FST index. The study of caries in heterogeneous populations such as recruits points to the need of taking more effective preventive measures in childhood and adolescence.

Intercondylar distances of the human temporomandibular joints.

In a sample which included subjects of the Croatian population we made measurements of intercondylar distances between the temporomandibular joints in radiographs. A total of 101 subjects of both sexes ranging in age from 20 to 80 years, mostly residents in Zagreb, were evaluated. We measured the intercondylar distances from the condyle centers in the postero-anterior cranial radiographs which had previously been examined and traced on acetate paper. The measuring points were digitized prior to measurements. A special system of coordinates was devised for each radiograph. The results of our measurements were assessed by ANOVA analysis. The intercondylar distance between the two temporomandibular joints was within the range of 110 and 145 mm, with the mean of 126 mm. In men the intercondylar distance was within the range of 116 and 145 mm, with the mean of 130.2 mm. In women the distance ranged from 110 to 138 mm, with the mean of 123.5 mm. There was a significant difference between the two sexes. From a review of the literature, it is apparent that the results of our measurements do not support the results of similar studies assessed by a number of researchers in other countries. The intercondylar distance in the Croatian sample was 5.25% larger than the maximal values of the same parameters in other populations suggesting larger craniofacial skeletons. The development of this radiographic assessment method should improve evaluation of subjects seeking treatment.

Dental evidence of exhumed human remains from the 1991 war in Croatia.

The aim of this paper is to present the post mortem dental evidence and dental health of the victims exhumed throughout the territories of Croatia that was temporarily occupied during the war. A total number of 62,432 teeth out of 1,253 human bodies exhumed from 5 different counties were analyzed. The majority of victims inhabited those areas before 1991. Post mortem dental characteristics were analyzed according to the American Board of Forensic Odontology and WHO methodology. The results show the highest level of the dental health before 1991 in the Vukovarsko-Srijemska County. The decayed (D), missing (M), filling (F), teeth (T), DMFT of that County was at the lowest level i.e. at 5.2. In all of the other counties, it was always between 6 and 12. The material most frequently used for the dental fillings was amalgam. Its highest frequency level was recorded in the County 4 (8%) and lowest in the County 1 (1.5%), p<0.001. The most frequent prosthodontic appliances were acrylic dentures. Their frequency was lowest in the County 5 (1.3%) and highest in the County 3 (11.6%), p<0.001. Determination of sex and dental age showed that victims were mostly men (79%) of middle and elderly age (89%). Teeth were useful also for monitoring of the quality of exhumations--taking into consideration number of empty dental sockets. The highest number of empty dental sockets was recorded in the County 3 (40.4%) and lowest in the County 1 (13.5%), p<0.001. Even after many years in the soil, teeth proved to be the most preserved human organs and valuable indicators of identity as well as of the way of life before death.

A 3D visualization and simulation of the individual human jaw.

A new biomechanical three-dimensional (3D) model for the human mandible based on computer-generated virtual model is proposed. Using maps obtained from the special kinds of photos of the face of the real subject, it is possible to attribute personality to the virtual character, while computer animation offers movements and characteristics within the confines of space and time of the virtual world. A simple two-dimensional model of the jaw cannot explain the biomechanics, where the muscular forces through occlusion and condylar surfaces are in the state of 3D equilibrium. In the model all forces are resolved into components according to a selected coordinate system. The muscular forces act on the jaw, along with the necessary force level for chewing as some kind of mandible balance, preventing dislocation and loading of nonarticular tissues. In the work is used new approach to computer-generated animation of virtual 3D characters (called "Body SABA"), using in one object package of minimal costs and easy for operation.

Analysis of bone tissue mechanical properties.

This paper deals with the torsional moment depending on the angle of torsion of the compact bone in laboratory animals and humans. Based on the data from laboratory animals, obtained by measurement, the data on dependence of the torsional moment and the angle of torsion were assumed for humans. Measurements were carried out on four groups of compact bone in laboratory animals. One was the control group, and three other groups were treated by various vitamin D3 metabolites. Equal measurements were performed in only one group of compact bone in humans, due to the impossibility to treat humans with vitamin D3 metabolites. Functional relations between the angle of torsion and the torsional moment for all groups of animal body tissue were determined by measurements, and the results were used to assume the reaction of human compact bone tissue if treated by vitamin D3 metabolites.

SEM analysis of tooth enamel.

SEM analysis contains researches of tooth enamel surfaces of two populations. First group of samples is tooth enamel of prehistorically ancestor from Vucedol and the second group of samples is enamel of modern Croatian citizen. Even on small number of human teeth samples from cooperage site of Vucedol (3,000 BC) and today's Croatian people, we can conclude about chewing biometry of prehistorically ancestors and today's modern Croatian people, comparing interspecifically the morphology of enamel microdefects. With the interspecific comparison of morphology changes on tooth occlusal surfaces, we can connect the size and shape of abrasive particles and diet with microdefects of tooth enamel.