The importance of upper first permanent molars position for the orthognatic occlusion

Development of the dental arches and occlusion in permanent dentition can be divided into several stages and has to be observed regularly. The first permanent molar eruption is related to the onset of significant changes in the developing occlusion. Although this tooth is seen as the `key to occlusion` its value as an anchorage is debatable.The aim of the article is to study the correct position of the upper first molars in the two planes of space - the sagittal and transverse planes.In this article the position of the first upper molar is examined with the aid of diagnostic records, such as study cast, orthopantomogram (OPG), and lateral cephalometrics. A literature review includes Bulgarian and foreigner authors.Angle, who in 1899 referred to the maxillary first permanent molars as the `key to occlusion`, was the first to mention their importance within the dentition. According to Angle, the line passing through the middle of the mesiobuccal cusp of the upper first molar coincides with the line passing through the buccal groove of the lower first molar. After Angle, other authors have discussed the position of upper molars from different point of view, such as their relation or position in the maxilla, anteroposterior axial inclination and rotation. As indicated by Lamons and Holmes molar rotations commonly exist in Class II malocclusions. The molars are usually rotated around an axis lingual to their central fossae. In an ideal occlusion the buccal surfaces of the upper first molars are usually parallel to each other.On the OPG Kurol and Bjerklin measured the axial mesial inclination of upper first molar. The tipping of the molars is measured by the angle formed between the tangent line to the mesial surfaces of the root and crown and the line through the lower margins of the left and right orbits.According to Sassouni, the mesial contour of upper first molar should to lie on the 4th arc - the temporal arc. If the molar is anterior to this arc, a treatment with distalization could be initiated. The temporal arcnasion distance measured on the radius is equal to the distance from point ANS to the upper first molar. The position of the upper first molar varies with the position of the upper central incisors. The basic hypothesis is that if the upper first molar has a fixed position in the face, any increase in the total upper dental arch length will be transferred to the incisor area. Any change in the anteroposterior position of the upper first molar could influence the position of the mandibular- leading to Class II malocclusion.Ricketts pointed out that the average distance from the pterygoid vertical (PTV) to the distal surface of upper first molar is the sum of the age of the patient + 3mm, in a growing patient. This diagnostic method can help the orthodontist to decide whether to extract teeth or to distalize the molars.Any loss of space in the arch is a justification for early orthodontic treatment. Mediopalatal rotation of the upper molar is an additional problem in the final phase as well. The rotation of upper first molars is measured by the angles formed by the intersection of lines going over the tips of the mesiopalatal and distobuccal cusps of each molar (Ricketts line) with a straight line marked over the palatine raphe.The problem of reduced arch length has an impact on the final treatment stage when the major orthodontic goal is establishing a tight teeth intercuspation. The molars influence the transfer of occlusal forces to the facial skeleton. The upper first molar tolerates more changes in the position than the lower one. The correct position of the upper molar ensures a stable occlusion with significantly low grade of relapse

The influence of socio-demographic characteristics on maxillary first molar derotation in children with mixed dentition

Естетиката и стабилният резултат са крайна цел на всяко ортодонтско лечение. В основата на стабилния резултат стои ортогнатната оклузия и идеалната зъбна дъга. Постигането на този резултат се влияе и от правилно проведената първична и вторична профилактика още от ранно смесено съзъбие.Целта на настоящото изследване е да се направи социодемографска характеристика на деца с изменения в ротацията на горен първи молар при смесено съзъбие.Материал и методи: Изследвани са общо 681 деца на възраст между 7 и 10 г. Ротацията на горния първи молар е измерена според методите на Frie, Henry и Vigano и резултатите са представени според пол, възраст и големината на ротация на горните първи молари според зъбния клас при молари. Резултатите са обработени статистически, като са използвани дескриптивен, вариационен и сравнителен анализ.Резултати и обсъждане: Статистически значима разлика беше намерена по отношение на показателя пол, като при момичетата се наблюдава по-съществено ротиране на горните първи молари в сравнение с ротацията при момчетата. И при десните, и при левите молари момичетата са с по-голяма ротация на моларите. Не беше намерена съществена разлика според възрастовия показател въпреки вариациите в ротацията. Най-често срещана е двустранната медиопалатинална ротация на горните първи молари.Заключение: Възрастта на децата не се явява фактор при ротирането на горните първи молари. От друга страна полът е показател при ротирането на горните първи молари, като при момичетата се констатира по-голямо ротиране в сравнение с момчетата.Esthetic facial appearance and long-term stability of normal occlusion are the major goals of orthodontic treatment. Meeting these goals is based on orthognathic occlusion and a well-aligned arch. The accomplishment of these goals depends on proper and well-timed prophylaxis performed in early mixed dentition.AIM: The purpose of this study was to evaluate the influence of socio-demographic characteristics on maxillary first molar rotation in mixed dentition.MATERIALS AND METHODS: The sample included 681 untreated patients aged 7-10 years who were evaluated with the aid of the Friel Henry and Vigano analysis methods for assessment of the magnitude of maxillary molar rotation. The results were summarized and presented by gender, age and dental class. Then they were processed statistically by using descriptive, variation and comparative analysis.RESULTS AND DISCUSSION: Statistically significant difference was observed in this study in two groups divided by gender - the incidence of upper first molar rotation is higher in girls than in boys regardless of the side - left or right. No significant impact of age on molar rotation was observed. The most frequently established malposition is bilateral mediolingual rotation of the upper permanent first molars.CONCLUSION: It appears that age is not a factor influencing maxillary permanent first molars but the gender is an important factor to be considered. The incidence of rotation is higher in girls than boys

Histochemical alterations in liver of Common Carp Cyprinus carpio (Linnaeus, 1785) after glyphosate exposure: Preliminary study

The present study was designed to provide some preliminary data on the toxic effects of 96 h exposure to glyphosate on the liver of Common Carp (Cyprinus carpio L.) under ex situ conditions. For this purpose we used Sudan III staining which could be suggested as fast and low-cost histochemical biomarker for pesticide contamination effects

Effects of the insecticide

The main goal of the present work is to study the effects of the new neonicotinoid insecticide „Actara 25 WG" on the intensity of expression of glycogen in the liver of common carp (Cyprinus carpio L.) by using PAS-reaction on cryosections. Common carp is an economically important fish species, which is widely used as a bioindicator for the health of freshwater basins since it could also survive at very contaminated sites. We have used 6.6 mg/L, 10 mg/L and 20 mg/L of the test chemical under laboratory conditions. The results demonstrated that the intensity of staining of the PAS-reaction is directly proportional to the increasing concentration of the insecticide. In addition, this indicates that the amount of glycogen in hepatocytes also increased. Conglomerates of accumulated glycogen in certain hepatocytes were found at the highest concentration of the insecticide. Therefore, we consider that under the influence of „Actara 25 WG" the process of glyconeogenesis in the liver of the studied fish accelerates

Thiamethoxam causes histochemical changes in the liver of Aristichthys nobilis Rich., 1845

In the present study, we aimed to investigate the effects of the neonicotinoid insecticide thiamethoxam on the hepatic glycogen in bighead carp (Aristichthys nobilis Rich.). Fish were exposed to 6.6 mg/L, 10 mg/L and 20 mg/L of the insecticide under laboratory conditions for 96 hours. The PAS-reaction was applied to liver cryostat sections in order to indicate the amount of glycogen. The results showed that the hepatic glycogen amount increased with increasing the insecticide concentrations. On the other hand, we observed glycogen conglomerates in certain hepatocytes. Hence, our results demonstrated an enhanced process of glyconeogenesis in the fish liver under the influence of thiamethoxam

DEVELOPMENT OF PROTOCOL FOR ANALYSIS OF ACID NITRATING MIXTURE

Technological control of nitration of organic compounds needs data about a composition of acid nitrating mixture before and after nitration. Content of water is a crucial factor for efficiency and safety of the nitration process. The industrial laboratories demands for fast, accurate, precise, low cost and easy to maintain analytical methods. This paper presents the development of a protocol for determination of composition of acid nitrating mixture. The determination of nitric acid is based on redox back titration. Determination of sulfuric acid is based on direct precipitation titration. Water content is determined by calculation. The proposed method showed good accuracy, precision and selectivity, with recoveries (99.80±0.06)% H2SO4 and (98.91±0,80)% HNO3,and total analysis time 20 min.

Abstracts Of The Proceedings And The Posters From The Third Scientific Session Of The Medical College Of Varna

October 2-3, 201