Preventive sealing of dental fissures with Heliosil: a two-year follow-up

Due to their shape and configuration of dental crown, especially its biting surface with numerous pits and fissures permanent molars are suitable sites for retaining food remnants and bacteria. For this reason, preventive efforts and early prophylactic procedures should prevent the development of caries at these critical sites. Deciduous and permanent teeth of 300 children aged 6-7 years with healthy parallel teeth were included in the study. Fissure sealing was performed on one side, whereas contralateral teeth served as controls. During a two-year period, control examinations with finding recording were performed every six months. During the two-year follow-up period, the sealed teeth remained free of caries as long as the coating persisted. In deciduous teeth, the sealant was first observed to be missing at 18 months in 5%, and at 24 months in 8% of the teeth. None of these teeth was affected by caries, suggesting that a part of the sealant was retained in the fissures. In permanent teeth, caries developed in 18% of the sealed teeth at 24 months.

The influence of tooth wear on root canal dimensions

The objective was to investigate the relations between tooth wear and root canal dimensions. The experimental group comprised 100 cuspids (canines), 50 of which had advanced abrasion and 50 were without it The dimensions of root canal were investigated at the light microscope level in order to define their vestibulo-oral and mesio-distal diameters in all three thirds. In the groups of teeth without abrasion the MD diameters of root canaliculi in their cervical thirds were greater than in the teeth with advanced abrasion. In the apical third the MD diameters of canaliculi were highly variable in teeth with no signs of abrasion. In the group of teeth with abrasion the MD and VO diameter values of the cervical thirds were significantly smaller than in the group of teeth without abrasion. In the mid-thirds the values of MD diameters were highly variable in the group of teeth with abrasion, whereas the VO diameter values were much greater than in the teeth without abrasion. As regards to the apical thirds, the VO diameter values were greater than in the control teeth. The data presented herewith contribute to better knowledge about tooth wear and are highly useful in restorative and reconstructive dental procedures.

Vomer as relevant factor in the mastication forces transmission system

In the region of the posterior segment of bony palate and nasal cavities in both sides, the following three bones come together: the upper jaw, the palatal and the sphenoid bones. The perpendicular upper palate lamina laterally leans on the corpus of the upper jaw and on the wing process of the sphenoid bone. It is the posterior bony transmission system that has been selected as a separate study entity, which is otherwise a functionally inseparable part of the overall system of trajectories of mastication forces. It is a supporting element that begins at the dental alveolus of the wisdom tooth, ascends along the tuber maxillae and by the wing process of the sphenoid bone transmits the mastication load to the body of the sphenoid bone, i.e. into the mid-portion of the neurocranial base. By observing the characteristics of the vomer and measurement of distances between its morphological markings, or craniometric landmarks, together with its fitting into the harmonic analysis of face and head, the essential role of vomer has been established in regard to the trajectory system of mastication forces which has enabled us to create the basis for further biomechanical research of this phenomenon using photoelasticimetric procedures.

Morphometric characteristics of toothless lower jaw ridge as a bed for total lower jaw prosthesis

Analysis was made of 44 solid casts of toothless lower jaws. Stereophotogrammetry, a measurement procedure in photogrammetry, was used as a method in the measurement of solid casts. Adequate instruments and method of measurement made it possible to objectify anatomical and morphological structures of toothless lower jaws. The anterior width of the ridge in the region of canines was 22.70-35.50 mm. The posterior width in the first molars region was 43.30-59.10 mm, with statistically significant difference between the genders. The width at the level of posterior ridge of mandibular tubercle was 52.10-70.00 mm, with statistically significant difference between the genders. The length of the alveolar ridge between the symphysis and the tangent line of posterior ridge of mandibular tubercle in the medial line was 34.70-49.00 mm, without statistically significant difference between the genders. The surface of the toothless ridge is at the same time the surface of the total lower prosthesis bed. The size of the surface depended on the resorption and relation between the alveolar ridge and the surrounding active structures; it ranged between 103.21-205.50 mm2. The mean value being 145.99 mm2. The values obtained in our study are in approximate accordance with the reference literature data. They are the results of accurate measurements of solid casts.

Prevalence and intraoral distribution of dentin hypersensitivity among students

The exposed dentin which is the result of the consequence of the enamel loss (by erosion, abrasion, attrition), gingival recession or periodontal therapy, as well as anatomic defects often as its result has dentinal hypersensitivity. The purpose of this work is to examine the frequency of dentinal hypersensitivity in relation to the subjective estimation of the examined persons and objectively, by intraoral examination. Forty persons, students from the School of dentistry of average age of 22.35 years were tested and analysed. Subjective data are achieved by the method of questionnaire while the objective ones by pulling the probe in the area of the tooth neck for the purpose of mechanical testing and by air syringe for the cold stimulus. The results show that the clinical hypersensitivity amounts 52.5% in relation to the subjective data 32.5%. The duration of hypersensitivity amounts in average 18 months and the strongest way of its demonstration is the cold and mechanical stimulus. The half of the examined brush their teeth twice a day out of which 72.5% do that by the half hard nylon brush, and the percentage of teeth with cuneiform defects amounts to 4.45. The often phenomenon of dentin hypersensitivity already among the young underline the need of preventive action and removing the damaging factors which contribute to the start of hypersensitivity of the nude dentin.

A biomechanical analysis of deformation and strain on lower jaw model

Forces, occurring as result of orthodontic appliances, present a guiding system which controls force activity during the growth and development of lower jaw. By qualitative photoelasticimetric analysis author decided to evaluate the influence of extension apparatus to the lower jaw. The concentration and stress distribution, intensity and force direction on contacts with insert (extensor device) were analysed on araldyte lower jaw models. Three different loadings 41.0, 57.4 and 73.8 N under four different loading conditions with and without the correction appliance were used. The results of investigation indicated that the force created by the orthodontic appliance is correct at the beginning. The change from surface contact to linear and punctual contact increased the static moment and local stress, resulting in new regional conditions.

Assessment of position of foramen mandibulae in recent adult population

Accurate knowledge about the morphology and topography of foramen mandibulae is of great practical importance in anaesthesia of inferior alveolar nerve. A certain number of skeletotopical relations may be used as valuable orientation points. Because of the controversies about these marking points it has been decided to perform measurements on a large sample of macerated mandibulae that are significant to location and shape of foramen mandibulae (FM) and lingula in relation to the surrounding orientation points. The measurements were taken in antero-posterior and infra-superior directions. In AP direction the distance between PRR and FM was measured; the obtained sample average was 15.03 at variability of Qv 12.18%; ARR-FM distance had the average value of 17.52 at Qv of 50%; the CT-FM distance had the average of 14.81 at Qv of 8.17%. In infra-superior direction the following measurements were made: AM-FM with the average of 21.10 at Qv of 13.98%; IM-IF with the average of 25.19 at Qv of 16.18%; PCO-FM with the average of 44.17 at Qv of 10.48%; and PCR-FM with the average of 42.79 at Qv of 10.87%. Extreme heterogeneity was noticed in the measurements of lingula. In the antero-posterior plane the FM is located in the middle of the CT-PRR distance, i.e., in measurements in which the external oblique line was used as anterior point, FM was located at the juncture of two anterior thirds and the posterior third of ramus mandibulae. In infra-superior direction the lowest FM point was closer to AM than to IM, indicating a somewhat lower position of FM. The mean value of FM depth was 4.31 and the most commonly found shape of the foramen was that of the elongated type (45%). The lingula was prominent, although unevenly, in 51% of study samples.

Effect of unilateral function on craniofacial growth

The present study is aimed at experimental research of the effects of functional matrices upon the formation of functional units. The sample consisted of 15 experimental dogs (five dogs per each experiment) and five controls. Three experiments were carried out: neurectomy of the right mandibular nerve, circumvention of the right nostril and enucleation of the right eyeball. The results showed no statistically significant difference between age and animal sacrifice time interval. The controls manifested the significant differences in the length, breadth and height of the upper mandibular body consistent with their natural asymmetry. Neurectomy of the right mandibular nerve did not manifest statistically significant differences whereas the sample was too small, animal sacrifice time interval too short and passive movements of that mandibular side were still present after the operation. Circumvention of the right nostril revealed in the nasal opening breadth, which for the very nature of the operation and only a partial exclusion of the right side function could have been anticipated. Enucleation of the right eyeball eliminated the visual function in the right face causing changes in the midface, i. e. in the breadth and height of the nostril. The findings confirmed the initial assumption on the correlation between the removal of potential growth factors and increase of the opposite face parameters. The changes were most prominent in the mid of the head which can be related to its developmental and structural features.