The morphology of alveolar bone of the mandibular second and third molars in skeletal Class III patients.

OBJECTIVES: To investigate the alveolar bone morphology of the mandibular second and third molars in skeletal Class III patients from a buccolingual direction. METHODS: Sixty skeletal Class III patients were recruited. The alveolar bone width, buccal cortical bone thickness and lingual cortical bone thickness were measured in five planes from mesial to distal and at five depths from gingival to root. The effects of the gender of the patients, the second molar lingual inclination and the third molar on alveolar bone width and cortical bone thickness were evaluated. To explore the effect of third molar extraction on alveolar bone morphology, the measurements before and after third molar extraction were compared. RESULTS: The impacted third molar had significantly greater alveolar bone width and thicker buccal cortical bone at the cervical third of the molar, while the erupted third molar had greater alveolar bone width at the apical third. Three weeks after third molar extraction, these advantages would weaken owing to the reconstruction of the alveolar bone. Patients with lingually inclined molar were observed to own thicker lingual cortical bone. Males tended to have greater alveolar bone width, but no significant differences were shown in this study. CONCLUSIONS: The growth of the third molar and the second molar lingual inclination affect the alveolar bone morphology of the mandibular second and third molars significantly, but gender has trivial effects on the morphology. The alveolar bone morphology of the mandibular second and third molars would change 3 weeks after third molar extraction.

Combining the third molar mineralization to further improve the accuracy of the Kvaal's method in dental age estimation of subadults in northern China.

The morphological changes based on deposition of secondary dentin and mineralization of the third molar have been proven to be related to chronological age. However, Kvaal's method on the theory of deposition of secondary dentin was controversial with respect to dental age estimation in the recent research. The aim of this study was to combine the parameters of Kvaal's method with relatively high correlation coefficients and mineralization stages of the third molar to improve the accuracy of predicting the dental age of subadults in northern China. A total of 340 digital orthopantomograms of subadults aged from 15 to 21 years were analysed. A training group was used to test the accuracy of the original Kvaal's method and to establish novel methods for subadults in northern China. A testing group was used to compare the accuracy of the newly established methods with the Kvaal's original method and with published method specifically used in northern China. To increase the feasibility of our estimation model, we combined the mineralization of the third molar to build a combined specific formula. The results showed that the combined specific model increased the coefficient of determination to 0.513, and the standard error of the estimate was reduced to 1.482 years. We concluded that the combined specific model based on the deposition of secondary dentin and mineralization of the third molar could improve the accuracy of dental age assessment of subadults in northern China. Key Points: The decrease in the dental pulp cavity based on deposition of secondary dentin is a useful variable for assessing age.A total of 340 orthopantomographs were used in this research, including 278 in training groups and 62 in testing groups.Original Kvaal's method underestimated the dental age for subadults in northern China.The equation of combined specific method constructed in our study was proved more suitable to calculate dental age for subadults in northern China.

[Surgical treatment tactics in patients with third molars located close to mandibular canal]. / Taktika lecheniya patsientov pri udalenii tret'ikh molyarov nizhnei chelyusti, prilezhashchikh k nizhnechelyustnomu kanalu.

The tight fit of the roots of the third molars to the mandibular canal is the main predisposing factor of injury to the inferior alveolar nerve during tooth extraction surgery. Surgical treatment of 92 patients diagnosed with pericoronitis, retention of the third molar of the mandible, close fit of the roots of the third molar to the mandibular canal was performed. Four types of close fit of the roots of the third molars to the mandibular canal were revealed, according to CBCT, OPTG and clinical data. Most cases of paresthesia after the removal of the third molars are associated with an anatomical variation in the structure of the mandibular canal, in which the canal walls are partially formed by the cement of the tooth root. Two variants of postoperative management of the surgical wound are proposed, when an open section of the neurovascular bundle is detected at the bottom of the hole.

Latent forms of the carious lesion of human lower third molars.

OBJECTIVE: Introduction: The most pronounced thinning of the enamel is in the intercuspal fissures of the third molars, which are characterized by a wide variety of shapes and sizes up to the abnormal disruption of their development and teething, which often causes all kinds of clinical complications. The aim: The purpose of the paper was to obtain the data on the structural state of the third molars and identify their most damaged areas in the latent form of dental caries. PATIENTS AND METHODS: Materials and Methods: 10 lower third molars with an intact crown without clear external signs of tooth decay have been examined. The teeth were embedded into epoxy resin, using the "Himkontakt-Epoxy" glue. Upon the completion of full polymerization, the resulting epoxy blocks were cut by the separation disk. Afterwards, the cross-cut ends with the naked tooth tissues were grinded and polished to obtain even unscratched slice, which was subsequently etched in Trilon-B (disodium salt EDTA) with the follow up staining in 1% borax methylene blue solution. Epoxy tooth slices were studied with the light optics in the reflected light using the MBS-9 binocular loupe, equipped with a digital camera adapter. RESULTS: Results: The process of tooth decay is of endogenous origin. The specimen of the third lower molar shows all pathomorphological signs of the latent carious lesions. Impacted lower third molar with deep carious was detected. It is obvious that, being in the subcortical zone of the alveolar ridge of the lower jaw, this abnormally developed tooth could not be exposed to any external effects. CONCLUSION: Conclusions: The microscopic study of the tooth, found in the ovarian dermoid cysts, showed that it was affected by caries that completely excludes the exogenous factors in its origination. We hypothesize that the mechanism of tooth decay directly involves the immune responses, antigens of which are (in certain circumstances) proteins of the dentin and enamel. This is the rationale for introduction into the current nosology the term "carious disease" instead of "dental caries".

Useful tools for the age 18 estimation in forensic radiology / 中国法医学杂志

The age of 18 is an important criterion in judicial trial, immigrant and competitive sports. Consequentially, the estimation of age 18 is a key issue in forensic practice and research. The extremitas sternalis claviculae, iliac crest, third molar, and the proximal limb of the limb bone were usually used as indictors of age 18. The results of the previous studies demonstrated that those indictors could be beneficial to the estimation of age 18. The X-ray, CT, ultrasound and MRI of different indictors were widely utilized for the estimation of age 18, particularly the thin-layer CT. But due to the non-radiation, MRI will be a trend for forensic age estimation in the future. Whilst in the previous studies, the descriptive analysis was applied for the estimation of age 18, but due to the low statistic efficiency, it is unsuitable for forensic age estimation, and the future studies should pay attention to the high efficiency statistical methods, for instance, the ROC curve or the data mining.

Caracterización de la formación y el desarrollo de los terceros molares / Characterization of the formation and development of the third molars i: en

Se realizó un estudio observacional, descriptivo y transversal en el Departamento de Ortodoncia de la Clínica Estomatológica Provincial Docente "Mártires del Moncada" de Santiago de Cuba, con vistas a caracterizar la formación y desarrollo de los terceros molares según edad, localización, sexo y grupo étnico, en el período de mayo de 2010 a igual mes de 2011. La información necesaria se obtuvo de las historias clínicas y radiografías panorámicas de los pacientes ingresados en dicho Departamento. En la casuística, la edad promedio de aparición de la cripta fue a los 8,7 años y de los movimientos eruptivos a los 11-12,2 años; asimismo se concluyó que la arcada inferior, el sexo masculino y la raza negra se adelantaron en alcanzar las diferentes etapas de formación y desarrollo de los cordales. Se recomendó llevar a cabo otra investigación al respecto, pero con un número mayor de pacientes y en edades más tempranas, así como proponer un esquema de formación y desarrollo para el tercer molar en el territorio.

An observational, descriptive and cross-sectional study was carried out in the Department of Orthodontics of "Martires del Moncada" Provincial School of Dentistry in Santiago de Cuba, with the purpose of characterizing the formation and development of the third molars according to age, location, gender and ethnicity, in the period of May 2010 to the same month of 2011. The necessary information was obtained from medical records and panoramic x-rays of patients admitted to this department. In the case series the average age of the crypt onset was 8.7 years and the eruptive movements from 11 to 12.2 years; it was also concluded that the lower arch, male sex and black race were advanced to reach the different stages of formation and development of wisdom teeth. It was recommended to carry out another study on this, but with a greater number of patients and at younger ages, and to propose a scheme of the third molar formation and development in the territory.

Avaliação do espaço retromolar para erupção dos terceiros molares inferiores relacionados ao tipo facial em pacientes ortodônticos / Evaluation of retromolar space to lower third molar eruption related to facial type in orthodontic patients

O objetivo deste trabalho foi avaliar o espaço retromolar disponível para a erupção do terceiro molar inferior e relacioná-lo com o tipo facial, foram selecionados para a amostra 130 pacientes de ambos os gêneros e dos mesmos foram obtidos radiografias em norma lateral da cabeça e Radiografias panorâmicas. Utilizou-se o índice VERT de Ricketts (1982), para classificar o tipo facial em: Neutrovertido, Retrovertido e Provertido. O espaço retromolar foi classificado em: Suficiente, Ausente e Insuficiente, mensurado a partir do ponto Xi até a face distal do segundo molar inferior. Nos dados obtidos, foram aplicados as análises estatística comparativa do Qui-quadrado e de concordância através do índice de Kappa. Nos resultados obtidos, quanto ao gênero, o feminino apresentou espaço retromolar Ausente em 60,5%, resultado superior ao masculino que foi de 37%. Enquanto o masculino obteve espaço retromolar Suficiente de 20,4%, valor superior aos 7,9% do gênero feminino. No espaço retromolar Insuficiente, o gênero masculino apresentou 42,6% e o feminino 31,6%. Em relação ao tipo facial Provertido apresentou espaço retromolar Ausente de 24,4%, espaço Suficiente 26,8% e espaço Insuficiente 48,8%. No Retrovertido o espaço retromolar Ausente foi de 62,5%, espaço Suficiente 6,3% e 31,2% de espaço Insuficiente. O Neutrovertido apresentou maior espaço retromolar Ausente, de 63,4% e apenas 7,3% de espaço Suficiente; sendo que, de espaço Insuficiente apresentou 29,3%. Concluiu-se que houve diferença estatisticamente significante entre os gêneros, onde o feminino apresentou espaço retromolar Ausente em porcentagem maior que o masculino (p<0,001); o tipo facial provertido apresentou espaço retromolar Suficiente em maior proporção e o retrovertido apresentou espaço retromolar Ausente em maior percentual.

The objective of this work was to evaluate the space to retromolar available for the eruption of the third molar inferior and to relate it with the face type, the sorts had been selected for the sample 130 patients of both and of the same ones panoramic x-rays in lateral norm of the head and X-rays had been gotten. Index VERT of Ricketts was used (1982), to classify the face type in: Neutrovertido, Retrovertido and Provertido. The space to retromolar was classified in: Sufficient, Insufficient, the mensurado from point Xi until the distal face of as molar Absentee and inferior. In the gotten data, the analyses had been applied comparative statistics of the Qui-square and agreement through the index of Kappa. In the gotten results, how much to the sort, the feminine one presented space to retromolar Absent in 60,5%, superior result to the masculine that was of 37%. While the masculine got space to retromolar Enough of 20,4%, superior value to 7.9% of the feminine sort. In the space to retromolar Insufficient, the masculine sort presented 42.6% and feminine 31.6%. In relation to the face type Provertido it presented space to retromolar Absent of 24,4%, Enough space 26.8% and Insufficient space 48.8%. In the Retrovertido the space to retromolar Absent was of 62,5%, Enough space 6.3% and 31.2% of Insufficient space. The Neutrovertido presented greater space to retromolar Absent, of 63,4% and only 7.3% of Enough space; being that, of Insufficient space it presented 29.3%. It was concluded that it had statistical significant difference between the sorts, where the feminine one presented space to retromolar Absent in bigger percentage that the masculine (p< 0.001); the proshed face type presented space to retromolar Enough in bigger ratio and the retrovertido one presented space to retromolar...