Causes of impacted maxillary incisors and progresses in orthodontic treatment / 上海交通大学学报（医学版）

An impacted tooth is a tooth that cannot erupt normally when its eruption is blocked or it is erupted in the wrong direction and posi-tion. The most commonly impacted teeth is the third molar, while in the anterior region, the most common is the maxillary canine, followed by the maxillary central incisor and the maxillary lateral incisor. In recent years, the treatment of impacted maxillary incisors often uses open and closed eruption techniques with traction. Although most of the prognosis is good, traction difficulties, root resorption and alveolar bone loss are often encountered in the case of root dilacerations. This article reviews the progresses in the treatment of impacted maxillary incisors.

The incisive papilla as a guide to maxillary anterior teeth position for complete dentures

Context: The incisive papilla as a guide for complete dentures. Aims: To evaluate incisive papilla as a guide to maxillary anterior teeth position for complete dentures. Settings and Design: To measure the linear distances from the incisive papilla to the maxillary central incisors in Odia population and compare it to other ethnic groups. Subjects and Methods: The subjects were selected following inclusion & exclusion criteria. The impressions of maxillary & mandibular arches were taken and poured with die stone to produce the cast. The incisive papilla & incisors were marked on casts with a pencil. The photographs of casts were traced on an acetate tracing paper. The anterior-most points of maxillary incisors, anterior, middle & posterior-most points of incisive papillae were marked on the tracing as A, I1,M, I2 respectively. The A to M and A to I2 distances were measured, analysed and compared with Caucasians, Southern Chinese, and Dravidians. Statistical Analysis: Independent sample “t” test and Analysis of Variance followed by the post-hoc Bonferroni test were used. Results: A sample of 100 subjects in the age group of 20 to 40 years with was selected. The A to M measurements of Odia population differed significantly from Caucasians but were similar to Southern Chinese population. The A to I2 measurements of Odia population differed significantly from Caucasians & Dravidians but were similar to Southern Chinese. Conclusion: The linear measurements from incisive papilla to maxillary incisors of the Odia population are similar to that of Southern Chinese but differ significantly from Caucasians and Dravidians.

Influence of anterior load and restorative procedure on maxillary incisors with different cervical wear morphologies / Influência do procedimento restaurador e de contato anterior em incisivos superiores com diferentes morfologias de desgaste cervical

The aim of this study was to evaluate the influence of different anterior load type and restorative procedure on stress distribution of maxillary incisors with different noncarious cervical lesions (NCCLs) morphologies. Three-dimensional models of a maxillary incisor were generated. Beyond the sound model (SO), five NCCLs morphologies were simulated: shallow (SH), notched (NO), concave (CO), wedge-haped (WS) and irregular with dual center (IR' and IR"). Composite resin restoration of all the models was simulated (R). Two different anterior loads were applied: 100N on palatine middle third (ML) and 500 N on palatine incisal third (IL). The data were obtained in MPa using the Maximum Principal Stress and Von Mises criteria and the statistical analysis was performed (paired t-test with 95% confidence level). The IL provided higher compressive stress than ML, mainly on WS (-136.3MPa), IR" (-117.5) and NO (-71.1 MPa). The highest tensile stress found within the restored models was on NOR with IL (19,1 MPa). The Von Mises results showed higher stress concentration on non-restored and IL models (p<0.001). The anterior load type and restorative status were determinant factors on stress distribution pattern changes, whereas NCCLs morphologies had little influence in maxillary incisors.

O objetivo deste estudo foi avaliar a influência de diferentes tipos de contatos anteriores e procedimentos restauradores na distribuição de tensões de incisivos superiores com diferentes morfologias de lesões cervicais não-cariosas (NCCLs). Modelos tridimensionais de um incisivo central superior foram gerados. Além do modelo hígido (SO), foram simuladas cinco morfologias de NCCLs: rasas (SH), entalhadas (NO), côncavas (CO), em forma de cunha (WS) e irregulares com centro duplo (IR' e IR''). Restauração com resina composta em todos os modelos foi simulada (R). Dois contatos anteriores diferentes foram aplicadas: 100N no terço médio palatino (ML) e 500N no terço incisal palatino (IL). Os dados foram obtidos em MPa utilizando os critérios de Tensão Máxima Principal e de Von Mises e a análise estatística foi realizada (teste t pareado com nível de significância de 95%). A IL proporcionou maior estresse compressivo que ML, principalmente em WS (-136,3MPa), IR "(-117,5) e NO (-71,1 MPa). A maior tensão de tração encontrada nos modelos restaurados foi na NOR com IL (19,1 MPa). Os resultados de Von Mises mostraram maior concentração de estresse nos modelos não restaurados e IL (p <0,001). O tipo de contato anterior e a presença de restauração foram fatores determinantes nas alterações do padrão de distribuição de estresse, enquanto as morfologias dos NCCLs tiveram pouca influência nos incisivos superiores.

Study on using laser Doppler flowmetry to determine the pulpal blood flow of immature maxillary incisors / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to evaluate the influence of age on the pulpal blood flow (PBF) of immature maxillary incisors of maxillary incisors, which was detected by laser Doppler flowmetry (LDF).</p><p><b>METHODS</b>LDF was used to detect the PBF value of maxillary central and lateral incisors of a child group (aged 7-13 years old) and a positive control group (aged 18-25 years old), as well as the central incisor of a negative control group (the central incisor had undergone endodontic treatment). We then compared the features of PBF in all groups with the influence of gender and position on PBF. The relation of maxillary central incisor and lateral incisor, age, and maxillary incisor were analyzed.</p><p><b>RESULTS</b>The PBF value of the negative control group was (2.08±0.73) PU. The PBF values in the positive control group in central and lateral incisors were (8.49±1.88) and (7.52±1.82) PU. In the child group, PBF values in central incisors and lateral incisors were (11.31±2.21) and (12.18±2.65) PU. A significant difference was observed between different groups and between central and lateral incisors (P<0.01). Meanwhile, no significant difference was found in the PBF values between the right and the left parts in both males and females (P>0.05). Age had a linearity negative correlation with the PBF value of incisors in the child group. A linear negative correlation existed between the age and PBF of central and lateral incisors (r=-0.310 and r=-0.510, respectively) (P<
0.01).</p><p><b>CONCLUSIONS</b>PBF value decreased with increased age in children aged 7-13 years old.</p>

Cambios radiculares en pacientes tratados ortodoncicamente / Root changes in patients treated orthodontically

Resumen Introducción y objetivo: La reabsorción radicular apical externa (RRAE) asociada al movimiento dental ha sido tema de investigación en el campo de la ortodoncia y la endodoncia. La detección temprana traería un beneficio para el paciente y el profesional; ha sido descrita como una complicación o secuela del tratamiento de ortodoncia que resulta en la pérdida permanente de estructura radicular El dignóstico eficiente es un aspecto esencial para definir la terapéutica adecuada y el éxito del tratamiento. El propósito de este estudio fue evaluar los cambios en la longitud radicular y del conducto como consecuencia del tratamiento ortodóncico.< Materiales y métodos: Se evaluaron 42 dientes , incisivos centrales superiores de 21 pacientes (12 mujeres, 9 hombres). Los cambios en la longitud radicular y amplitud del conducto fueron determinadas por medio de mediciones radiográficas obtenidas antes de iniciar el tratamiento (T1) y posteriormente a los 6 (T2), 12 (T3) y 18 meses (T4) utilizando un posicionador de técnica paralela RINN® XCP® (DENTSPLY) y el Sistema de radiovisiografía CDR de SCHICK ®. las imágenes obtenidas se importaron y procesaron con el sistema DBS WIN®, aquí se llevaron a cabo las mediciones correspondientes. Resultados: Todos los Incisivos evaluados mostraron disminución de la longitud y de la amplitud del conducto radicular durante los 18 meses de tratamiento. Conclusión: La RRAE se puede detectar en etapas tempranas del tratamiento de Ortodoncia, se presenta más significativamente en los primeros 6 meses, parece estar relacionado con las fuerzas de la fase de alineación y nivelación.

Abstract Introduction and objective: External apical root resorption ( RRAE ) associated with tooth movement has been the subject of research in the field of orthodontics and endodontics. Early detection would bring a benefit to the patient and the professional; It has been described as a complication of orthodontic treatment resulting in permanent loss of root structure. Efficient diagnosis is an essential aspect in order to define appropriate therapeutic and treatment success. The purpose of this study was to assess changes in root length and canal as a result of orthodontic treatment. Materials and methods: 42 teeth, maxillary central incisors of 21 patients (12 women, 9 men ) were evaluated. Changes in root length and width of the canal were determined with radiographic measurements obtained before starting treatment (T1 ) and at 6 ( T2 ), 12 ( T3 ) and 18 months ( T4 ) using a RINN® XCP® ( DENTSPLY) positioner technique and CDR System radiovisiography SCHICK®. Images obtained were imported and processed with the WIN® DBS system with which the corresponding measurements were made. Results: All tested incisors showed decreased length and breadth of the root canal during the 18 months of treatment. Conclusion: RRAE can be detected at early stages of orthodontic treatment , it appears most significantly during the first 6 monthsof treatment and seems to be related to the forces during alignment and leveling phases.

Maxillary incisor retraction: evaluation of different mechanisms

OBJECTIVE: To mechanically evaluate different systems used for incisors retraction. METHODS: Three different methods for incisors retraction using 0.019 x 0.025-in stainless steel wire were evaluated. The samples were divided into three groups: Group A (retraction arch with 7-mm high vertical hooks); Group G3 (elastic chain attached to the miniimplant and to the 3-mm stainless steel hook soldered to the retraction arch); Group G6 (elastic chain attached to the mini-implant and to the 6-mm stainless steel hook soldered to the retraction arch). A dental mannequin was used for evaluation in order to simulate the desired movements when the device was exposed to a heat source. The analysis of variance (ANOVA) and the Tukey test were used (p < 0.05). RESULTS: The results demonstrated that Groups G3 and G6 exhibited less extrusion and less incisor inclination during the retraction phase (p < 0.05). With regard to incisor extrusion, statistically significant differences were observed between Groups A and G3, and between Groups A and G6 (p < 0.05). Regarding incisor inclination, statistically significant differences were observed between the three systems evaluated (p < 0.05). CONCLUSIONS: Arches with 6-mm vertical hooks allow the force to be applied on the center of resistance of the incisors, thus improving mechanical control when compared with the other two systems.

OBJETIVO: avaliar mecanicamente diferentes sistemas utilizados para retração de incisivos. MÉTODOS: três diferentes métodos de retração dos incisivos foram avaliados, utilizando arco ortodôntico de retração confeccionado com fio de aço inoxidável 0,019" x 0,025" de espessura. Os grupos foram divididos em: Grupo A (arco de retração com alças verticais de 7mm de altura), Grupo G3 (elástico em cadeia ligado do mini-implante ao gancho de aço inoxidável com 3mm de altura soldado no arco de retração) e Grupo G6 (elástico em cadeia ligado do mini-implante ao gancho de aço inoxidável com 6mm de altura soldado no arco de retração). Para essa avaliação, adequou-se um manequim odontológico de tal forma que possibilitasse simular os movimentos desejados, quando fosse exposto a uma fonte de calor. Após obtenção das medidas dos movimentos, realizou-se análise estatística. RESULTADOS: os resultados demonstraram que os grupos G3 e G6 propiciaram menor extrusão e menor inclinação palatina dos incisivos na fase de retração (p<0,05). Quanto à extrusão dos incisivos, houve diferença estatisticamente significativa entre os grupos A e G3, e A e G6 (p<0,05). Em relação à inclinação, ocorreu diferença estatisticamente significativa entre os três sistemas avaliados (p<0,05). CONCLUSÃO: arcos com ganchos verticais de 6mm soldados permitem aproximar a linha de ação da força ao centro de resistência dos incisivos, proporcionando melhor controle mecânico, se comparado aos outros dois sistemas.

Influence of anatomical barriers on maxillary incisor root resorption after orthodontic treatment with premolar extractions

INTRODUCTION: Apical root resorption is a frequent and occasionally critical problem in orthodontic patients undergoing induced tooth movement. One of the factors that might influence prognosis, especially in maxillary incisors, which most frequently present resorptions, are the so-called the anatomical barriers; that is, proximity of the buccal and palatal cortical bones to the maxillary incisor roots. OBJECTIVE: The purpose of this research was to investigate whether patients with excessive vertical growth really present a small distance between the alveolar cortical bones and the maxillary incisor roots, and whether there is a correlation between this distance and the root resorption index in comparison with patients presenting horizontal growth. METHODS: The sample comprised orthodontic records of 18 patients with extraction planning of first maxillary premolars and treatment by the standard and/or preadjusted edgewise brackets. Their initial and final periapical radiographs were evaluated to determine the amount of root resorption that occurred. RESULTS: On the palatal side, patients with excessive vertical growth (Group 2 - SN-GoGn > 43º) showed a narrower alveolar bone than the horizontal growth patients (Group 1 - SN-GoGn < 29º). However, the distance between the buccal cortical bone and the central incisor root apex showed no significant difference between Groups 1 and 2; CONCLUSIONS: It was concluded that there are no correlations between the proximity of buccal cortical bone, maxillary incisor roots and the root resorption index.