Clinical analysis of skeletal malocclusion, axial inclination in patients with short root anomaly of the maxillary central incisors / 口腔疾病防治

Objective @#To investigate the prevalence and distribution of skeletal malocclusion and axial inclination of the maxillary central incisors in short root anomaly (SRA) patients in Kunming city, to provide some reference and guidance for SRA patients′ clinical diagnosis and treatment and prevention in SRA patients. @*Methods@#A total of 1 000 cases were randomly selected from the CBCT database of patients admitted to the author′s hospital from January 2011 to July 2019, and a retrospective analysis was performed. A total of 27 patients with SRA were diagnosed (SRA group).The control group, consisted of 100 randomly selected patients from non-SRA patients. According to the clinical data and cephalometric data, skeletal malocclusion was divided into three subgroups: Class I skeletal malocclusion, Class II skeletal malocclusion and Class Ⅲ skeletal malocclusion. Additionally, the axial inclination of the central incisors was divided into three subgroups: the lingual inclination group, labial inclination group and normal inclination group. The two groups each according to sex, skeletal malocclusion and types of axial inclination of the maxillary central incisors were discussed. @*Results @# The prevalence rate of SRA in the selected population was 2.7%, and the prevalence of SRA in females was 3.67% (21/572) , which was higher than that in males by 1.4% (6/428), and was significantly different between sexes (χ2=4.562, P=0.033). There was a significant difference between SRA patients and control group in terms of skeletal malocclusion (χ2=8.710, P=0.013). Class Ⅲ skeletal malocclusion was the main type of skeletal malocclusion in SRA. There was a significant difference between SRA patients and control group in terms of the axial inclination of the maxillary central incisors (χ2=16.75,P<0.001). Lingual inclination of the maxillary central incisors was the main type of axial inclination of the maxillary central incisors in SRA. @*Conclusion@#There is a certain correlation between class Ⅲ skeletal malocclusion and lingual inclination of the maxillary central incisors and SRA, and the root-crown ratio and root shape of these patients should be evaluated before orthodontics are implemented.

Cone Beam Computed Tomography Analysis in 3D Position of Maxillary Denture.

The dynamic correlation between teeth and denture morphology as well as the morphological positions needs to be explored. METHODOLOGY: 63 adult patients with skeletal class III malocclusions that met the inclusion criteria were enrolled and imaged with Cone Beam Computed Tomography (CBCT), and Digital Imaging and Communications in Medicine (DICOM) data were collected. The torque angle and axial inclination were measured and analyzed for the corona, root, and entire body of every tooth on the maxilla. RESULTS: There is a statistically significant difference between the coronal axial inclination/coronal torque angle for the skeletal class III malocclusion cases and Andrew's six keys of occlusion. On the sagittal plane of the maxillary denture (except that the secondary molar is inclined medial-distally), the remaining teeth are inclined towards the labia with slightly larger angles compared to the normal occlusion. In the coronal direction, the maxillary anterior teeth tend to have a corona that inclines medial-distally, whereas the posterior teeth have a buccal inclination compared to the normal occlusion. CONCLUSION: Sagittal and transversal compensations prevail in maxillary dentures; for the camouflaged treatment design for skeletal class III, there is limited scope of sagittal and transversal movements on the maxillary denture.

Avaliação longitudinal da inclinação axial mesiodistal dos molares superiores decorrente do uso do aparelho Pendulum associado ao aparelho fixo por meio de radiografias panorâmicas / Longitudinal evaluation of axial mesiodistal inclination in maxillary molars as a result of using the Pendulum device associated with fixed appliance, through panoramic radiographs

O objetivo deste estudo foi avaliar, por meio das radiografias panorâmicas, o comportamento longitudinal da inclinação axial mesiodistal dos molares superiores decorridos cinco anos após o tratamento realizado com o aparelho Pendulum seguido de aparelhagem ortodôntica fixa e comparar os resultados com os valores médios normais. A amostra consistiu de 20 pacientes (14 do gênero feminino e 6, do masculino) com má oclusão de Classe II tratada por meio da distalização dos molares superiores. A média da idade, ao início do tratamento (T1), foi de 14,27 ± 1,62 anos, ao final do tratamento (T2), 18,59 ± 1,82 anos, e, cinco anos pós-tratamento (T3), 23,77 ± 2,04 anos. A média do tempo de tratamento foi de 4,36 ± 0,79 anos e de avaliação pós-tratamento foi de 5,18 ± 1,14 anos. Como grupo controle, utilizou-se os valores angulares médios normais de molares superiores obtidos por Ursi (1989), sendo que essa obtenção partiu de radiografias panorâmicas de indivíduos com oclusão normal apresentando idades entre 12 e 17 anos. Para a análise estatística, utilizaram-se os traçados das radiografias panorâmicas nas 3 fases (T1, T2 e T3). Os dados obtidos foram analisados estatisticamente pelo teste ANOVA dependente seguido do teste de Tukey. As médias das inclinações axiais mesiodistais nas fases T1, T2 e T3 foram comparadas com os valores médios normais pelo teste t independente. Os resultados apontaram que os primeiros molares superiores, ao término do tratamento ortodôntico, estavam mais inclinados para a distal, porém, cinco anos após, tenderam a verticalizarem-se naturalmente, voltando a ocupar uma posição próxima ao inicial. Quando comparados com os valores normais, somente o primeiro molar superior esquerdo apresentou, no período T2, valor estatisticamente significante diferente do normal. Os valores correspondentes para os segundos molares superiores não apresentaram estatisticamente significantes quando comparados entre si, nem quando comparados com os...

The objective of this study was to evaluate, through panoramic radiographs, the longitudinal conduct of mesiodistal inclination in maxillary molars five years after the treatment performed with the Pendulum device followed by fixed appliance and compare the results with normal mean values. The sample consisted of 20 patients (14 female and 6 male) with Class II malocclusion treated with molar distalization. The average age at pretreatment (T1) was 14.27 ± 1.62 years, at posttreatment (T2), 18.59 ± 1.82 years and at the long-term posttreatment (T3) 23.77 ± 2.04 years. The average length of time of the treatment was 4.36 ± 0.79 years and the evaluation of the long-term posttreatment was 5.18 ± 1.14 years. As a control, it was used the normal mean angular values of molar obtained by Ursi (1989), and this achievement came from panoramic radiographs of subjects with normal occlusion ranging in age from 12 to 17 years. Panoramic radiographs were taken for statistic analysis in all 3 stages (T1, T2, T3). The obtained data were statistically analysed through ANOVA Test dependent followed by Tukey test. The mean mesiodistal axial inclinations stages T1, T2, T3 were compared with normal mean values by the independent t test. The results showed that the first molars were more inclined to distal at posttreatment but five years later they tended to upright naturally, occupying the previous position, close to the original. When compared with normal values, only the left first maxillary molar showed in T2 a statistically different value to the normal. The correspondent values for the second maxillary molars did not show to be statistically significant when compared with each other, nor when compared with normal values. The treatment with the Pendulum, together with the orthodontic appliance, fosters an inclination of the molars to the distal, but tends to upright in the long-term posttreatment.

Fracture strength of the IPS empress crown : the effects of incisal reduction and axial inclination on upper canine / 대한치과보철학회지

PURPOSE: The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal reduction (2.0mm, 2.5mm, 3.0mm) and axial inclination (4degrees., 8.degrees, 12degrees.) of the upper canine. MATERIALS AND METHODS: After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and the universal testing machine was used to measure the fracture strength. RESULTS: 1. The fracture strength of the ceramic crown with 3.0mm depth and 12degrees inclination was the highest (839N). Crowns of 2.0mm depth and 12degrees inclination had the lowest strength (559N). 2. There was no significant difference in the fracture strength by axial inclination in the same incisal reduction group. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal reduction.

Fracture strength of the IPS empress crown: The effect of occlusal using depth and axial inclination on lower first molar / 대한치과보철학회지

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination (4degree, 8degree, 12degree) of the lower First Molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan). The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine(Zwick Z020, Zwick, Germany)was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 2.5mm depth and 12degree inclination was the highest (1789 N). Crowns of 1.5 mm depth and 4degree inclination had the lowest strength (1091 N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. Size of fragment was affected by the amount of occlusal reduction.

Fracture Strength Of The Ips Empress Crown: The Effect Of Occlusal Depth And Axial Inclination On Lower Second Premolar / 대한치과보철학회지

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth(1.5mm, 2.0mm, 2.5mm) and axial inclination(4 degrees, 8 degrees, 12 degrees) of the lower second premolar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement. The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine was used to measure the fracture strength. The results of this study were as follows: 1. The fracture strength of the ceramic crown with 2.5mm depth and 12 degrees inclination was the highest (1284 N).Crowns of 1.5mm depth and 8 degrees inclination had the lowest strength (951N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.

FRACTURE STRENGTH OF THE IPS EMPRESS CROWN:THE EFFECT OF OCCLUSAL DEPTH AND AXIAL INCLINATION ON UPPER FIRST PREMOLAR CROWNS / 대한치과보철학회지

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination (4degree, 8degree, 12degree) of the upper first premolar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and 12degreeinclination was the highest (630N). Crowns of 1.5mm depth and 4degreeinclination had the lowest strength(378N). There were no significant differences of the fracture strength by axial inclination in same occlusal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.

A cephalometric study on mesiodistal axial inclination of posterior teeth in open bite and deep bite / 대한치과교정학회지

For the purpose of investigating mesiodistal axial inclination of posterior teeth in normal occlusion group, open bite and deep bite group and investigating the correlationship between the axial inclination of posterior teeth and overbite of anterior teeth, a cephalometric study was performed on the subjects consisted of normal occlusion group(40), open bite group(71 : Angle's Class I 21, Class II, division 1 25, Class III 25) and deep bite group(64 : Angle's Class I 23, Class II, division 1 21, Class III 20). Mesiodistal axial inclination of posterior teeth to occlusal, mandibular and palatal plane were measured. The findings of this study were as follows: 1. Upper and lower posterior teeth were more mesially inclined to occlusal plane in open bite group than in deep bite group. 2. Lower posterior teeth were more mesially inclined in deep bite group than in open bite group in Angle's Class II, division 1 malocclusion but there were no significant differences in Angle's Class I and Class III malocclusion. 3. There was no significant correlationship between the axial inclination of posterior teeth to each plane and overbite of anterior teeth in open bite group. 4. There was a significant correlationship between the axial inclination of upper and lower second premolar to occlusal plane and overbite of anterior teeth in Angle's Class I, Class II, division 1 and Class III malocclusion.