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Objective: To compare torque expression characteristics between rectangular slot (0.022″ x 0.028″) Damon Q passive self-ligating brackets (Ormco, Glendora, Calif) and square slot (0.021″ x 0.021″) Pitts 21 brackets (OC Orthodontics) using 0.019″ x 0.025″ Stainless Steel and 0.020″ x 0.020" Titanium Molybdenum alloy wires at various incisal inclinations using finite element analysis. The null hypothesis was that there were no differences in torque expression in both tested groups. Methods: Reporting guidelines for in-silico studies using finite element analysis in medicine (RIFEM) were used. Damon Q and Pitts 21 brackets were scanned and 3D models generated. Brackets were placed on a 3-D model of a maxillary central incisor with its long axis inclined at 0°,5°,10°,15° and 20° to the occlusal plane. Final 0.019″ x 0.025″ SS and 0.020″ x 0.020" TMA archwires were inserted into slots of both tested brackets. Geometric models were converted into finite element models. Material properties were assigned for involved structures with automatic meshing performed by software. Torque movements were simulated with the FE program Ansys Space claim R 22. Results: Torque moment values, torque expression and Von - Mises stress was higher in Pitts 21 than Damon Q at all inclination angles. There was a gradual increase in the magnitude of values with decrease in incisal inclination. Conclusion: Square slot passive self-ligating brackets show superior torque expression characteristics as compared to rectangular wire-rectangular slot combinations. The FEM results should be validated with in-vivo studies in order to confirm the findings.

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OBJECTIVE: This retrospective study aimed to evaluate the sagittal root position, arch shapes, and alveolar bone thickness in classes I, II, and III of skeletal patterns. MATERIAL AND METHODS: Alveolar bone thickness, sagittal root placements, and arch morphologies in classes I, II, and III malocclusions were measured using 30 study models and 30 lateral cephalograms, both with a mean age of 16.5 years. Based on their sagittal relations, 30 participants were classified into three groups each (classes I, II, and III). The ANOVA test was used to calculate the results. RESULTS: Between the three classes, there were statistically significant differences in the AP jaw relationship and root placements. Sagittal root location and dental arch shape showed no statistically significant correlation. CONCLUSION: There was no correlation between the dental arch form and sagittal root position, and classes II and III were found to have higher mandibular incisor inclination. On all levels, oval arch forms were prevalent.

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PURPOSE: This cross-sectional study aimed to utilize quantitative polymerase chain reaction (qPCR) to investigate the influence of genetic variance over teeth inclination and angulation in orthodontic patients with Class I occlusion. MATERIALS AND METHODS: DNA was extracted from adolescent patients seeking orthodontic treatment in a single institution (from July 2018 to April 2020), who had CBCTs taken as part of initial standardized records. Patients had permanent dentition, Class I skeletal and dental classifications, with normal vertical and transverse skeletal dimensions, normal incisors inclination, no to mild crowding or spacing. qPCR was performed using genetic markers for candidate genes EPB41, TGFß3, GHR and PAX9. Three-dimensional teeth inclinations (TI) and angulations (TA) were evaluated using Invivo6 software and correlated with genotypes. Reliability of TI and TA was assessed using intraclass correlation coefficients (ICC). Mixed models and multiple linear regression analyses were used to assess the association between each single nucleotide polymorphisms (SNP) with tooth inclination (TI) and with tooth angulation (TA). The results were evaluated at the significance level of P<0.05. RESULTS: Twenty four adolescent patients with mean age of 13.4±2.4 years were included in the study. ICC showed adequate intra-examiner reliability for TI and TA (0.806

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INTRODUCTION: The aim of this study was to determine and compare the play and torque expression of self-ligating and conventionally ligated lingual brackets, with square and rectangular slots, when engaged with archwires of different size, cross section and material. METHODS: Passive play and torque expression of 3 types of archwires and 5 types of brackets from four different manufacturers were measured and compared using a dynamometer. Each archwire was tested five times in each bracket; passive play was compared to ideal values, while torque expression was tested at 5, 10 and 20 Nmm as clinically efficacious values. RESULTS: Regarding full thickness stainless steel archwires, the lowest passive play was found in STb brackets (2.66 ± 0.89°, Ormco, Glendora, CA, USA), which was statistically significantly lower than for ALIAS brackets (4.44 ± 0.75°, Ormco), In-Ovation L brackets (6.14 ± 3.22°, Dentsply GAC, Bohemia, NY, USA), Harmony brackets (7.76 ± 2.94°, American Orthodontics, Sheboygan, WI, USA) and eBrace brackets (9.46 ± 3.94°, Riton Biomaterial, Guangzhou, China). Increasing the torsional load to the greatest torsional load clinically applicable, there were no statistically significant differences between STb, ALIAS, In-Ovation L and Harmony brackets. CONCLUSIONS: STb and ALIAS brackets generated the lowest passive play; STb and In-Ovation L brackets showed the lowest angle of play at the greatest torque expression. These measurements allow to understand the accuracy of lingual systems and at the same time the amount of overcorrections to be applied in the setup in order to obtain high quality orthodontic treatments.

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PURPOSE: The goal was to determine whether changes in the inclination of lower incisors and canines upon orthodontic treatment with fixed appliances poses a threat for labial gingival recession in adult patients. METHODS: The sample of this prospective clinical trial consisted of 32 adult patients (mean age 25.08 ±6.50 years) treated with fixed appliances. Plaque and bleeding indices, probing pocket depth, clinical attachment level, gingival recession height (GR) and width (GRW), gingival thickness (GT), and keratinized tissue width were clinically recorded, while cone beam computed tomography (CBCT) was used to evaluate teeth inclination before (T1) and after treatment (T2). Oral hygiene, brushing habits, and smoking were controlled. RESULTS: During orthodontic treatment on 15 (8.33%) teeth (10 incisors and 5 canines), spontaneous complete improvement of pre-existing GR was observed. On 2 incisors, GR decreased and on 3 teeth GR did not change. Moreover, 1 incisor presented an increased GR, while 2 teeth developed new defects. Mean GR, GRW, and GT decreased significantly only on the incisors. Proclination of incisors and canines during treatment (compared with retroclination of the teeth) implicated a lower reduction in GR at T2: 0.19 mm (p = 0.034) and 0.18 mm (p = 0.037), respectively. Multiple regression analysis confirmed that more tooth proclination was associated with a higher risk for an increase in GR (p < 0.00). CONCLUSION: Properly planned changes in lower incisor and canine inclination can be carried out in adult patients without posing a high risk to labial gingival recessions if the individual periodontal biotype is respected. The reported outcomes underscore the orthodontic principle to keep tooth roots inside the alveolar bone.

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PURPOSE: To test the null hypothesis of no significant deviation between the center of rotation (CROT) and the center of resistance (CRES) during space closure in Angle class II division 2 subjects achieved using a completely customized lingual appliance (CCLA) in combination with class II elastics and elastic chains. METHODS: This retrospective study included 29 patients (male/female 11/18; mean age 15.6 [13-27] years) with inclusion criteria of an Angle class II/2 occlusion of least of half of a cusp, maxillary dental arch spacing, completed CCLA treatment (WIN, DW Lingual Systems, Bad Essen, Germany) in one center with a standardized archwire sequence and use of class II elastics and elastic chains only. Maxillary incisor root inclination was assessed by X­ray superimpositions of the maxilla at the beginning (T1) and the end (T3) of CCLA treatment. Using Keynote software (Apple®, Cupertino, CA, USA), the incisor's CROT was assessed with the point of intersection of the incisor axes (T1; T3) following vertical correction of overbite changes. CRES was defined at 36% of the incisor's apex-incisal edge distance. RESULTS: The null hypothesis was rejected: the mean CROT - CRES difference was 52.6% (p < 0.001). The mean CROT was located at 88.6% (min-max 51-100%) of the incisor's apex-incisal edge distance. Although 6.9% of CROT were located between the CRES and the alveolar crest, the vast majority (93.1%) were assessed between the alveolar crest and the incisal edge, or beyond. CONCLUSION: CCLAs can create upper incisor palatal root torque even in cases in which lingually oriented forces applied incisally to the center of resistance of the upper incisors counteract these intended root movements.

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OBJECTIVE: The aim of our study was to evaluate apical root resorption and changes in tooth inclinations, marginal bone height, and labio-lingual bone thickness at the mid-root and apical level in mandibular anterior teeth during the Forsus treatment using cone beam computed tomography (CBCT). METHODS: CBCT scans of 16 subjects (8 males and 8 females) with Class II malocclusion (age group: 13-29 years) taken before and 6 months after the Forsus treatment were evaluated for apical root resorption, tooth inclination, marginal bone height, and thickness of bone at the mid-root and apical level in mandibular anterior teeth. RESULTS: There was statistically significant root resorption of central incisors (0.39 mm) and canines (0.66 mm); a decrease in the angle of inclination for all teeth; an increase in the marginal bone measurement in labial (1.31 mm) and decrease in lingual (0.93 mm) aspect at the canine region; and an increase in bone width by 0.87 mm and 0.75 mm in central and lateral incisor regions, respectively, at the mid-root level lingually. At the apex level in the canine region, bone width increased by 1.4 mm labially, while it decreased by 2.18 mm lingually; it increased significantly for incisors in the lingual region. CONCLUSION: The Forsus appliance therapy causes clinically insignificant root resorption and bone changes, and clinically significant proclination of mandibular anterior teeth. The findings of the present study aid clinicians in proper case selection and reinforce the prevention of incisor proclination while using the Forsus therapy to achieve better treatment results and stability.

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The purpose of this study was to investigate the expansion of the maxillary sinus and the inclinations of posterior teeth in orthodontic patients with maxillary second premolar agenesis. A total of 30 subjects with one or two congenitally missing maxillary second premolars and retained maxillary deciduous second molars (a agenesis group) were selected and divided into a unilateral agenesis group (20 subjects with one maxillary second premolar missing) and a bilateral agenesis group (10 subjects with two maxillary second premolars missing). As controls, 30 sex- and age-matched subjects without agenesis of the maxillary second premolars were selected. Oblique cephalograms were used to investigate the association of maxillary second premolar agenesis and lower maxillary sinus size and posterior tooth inclinations. Agenesis of the maxillary second premolars induced significantly large lower maxillary sinus length, depth, area and mesial inclination of the maxillary first premolar, a significantly small anterior maxillary length, and a significantly more distal position for root apex of the maxillary first premolar. There were no significant differences in any measurements of the lower maxillary sinus and posterior teeth between the non-agenesis side in the unilateral agenesis group and the control group. Maxillary second premolar agenesis caused inferior and anterior expansion of the lower maxillary sinus and the mesial inclination of the maxillary first premolars with a distal position of root apex. Unilateral agenesis of the maxillary second premolar did not affect on the lower maxillary sinus size or posterior tooth inclinations of the unaffected antimere.

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RESUMEN Introducción: Las retenciones dentarias afectan al 17 % de los pacientes a nivel mundial y están consideradas actualmente como un síndrome, en que los terceros molares ocupan el primer lugar y cuya extirpación quirúrgica deviene la intervención más comúnmente practicada por los cirujanos maxilofaciales. Objetivo: Describir las características anatomorradiográficas de los terceros molares, así como su posible relación con variables epidemiológicas de interés. Métodos: Se realizó un estudio observacional, descriptivo y transversal en escolares del Instituto Preuniversitario "Antonio Alomá Serrano", perteneciente al área de salud del Policlínico Docente Asistencial "José Martí" de Santiago de Cuba, durante el período comprendido desde mayo de 2016 hasta febrero de 2017. Se utilizaron radiografías panorámicas indicadas a estos pacientes, en las que se efectuaron el análisis y la clasificación. Resultados: La mayoría de los dientes se encontraban en clase I (52,6 por ciento), clase C (51,9 por ciento), posición C (82,2 por ciento), verticales (47,7 por ciento) y sin aproximación sinusal (89,5 por ciento). Además se observaron relaciones significativas entre la edad y el color de la piel con respecto al espacio retromolar y la inclinación dentaria de este grupo molar, y entre el sexo y la inclinación. Conclusiones: Los terceros molares son los dientes con mayor variabilidad en cuanto a posición e inclinación intraósea y en edades avanzadas se logra suficiente espacio retromolar y verticalización en la mayoría de ellos(AU)

ABSTRACT Introduction: Tooth impaction affects 17 % of patients worldwide. It is currently considered to be a syndrome in which third molars occupy the first place. Surgical removal is the most common intervention performed by maxillofacial surgeons. Objective: Describe the anatomo-radiographic characteristics of third molars and their possible relationship to epidemiological variables of interest. Methods: A cross-sectional observational descriptive study was conducted of students from Antonio Alomá Serrano Senior High School, from the health area of José Martí University Polyclinic in Santiago de Cuba, from May 2016 to February 2017. The study was based on panoramic radiographs, which were analyzed and classified. Results: Most teeth were class I (52.6 percent), class C (51.9 percent), position C (82.2 percent), vertical (47.7 percent) and without sinus approach (89.5 percent). Significant relationships were found between age and skin color with respect to retromolar space and tooth inclination of this molar group, and between sex and inclination. Conclusions: Third molars are the teeth showing the greatest variability in terms of intraosseous inclination and position. In advanced ages most of them achieve enough retromolar space and verticalization(AU)

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OBJECTIVES: To evaluate alveolar bone support around cleft-adjacent maxillary central incisors (U1) in patients with unilateral cleft lip, alveolus and palate (UCLAP) in the late mixed dentition and to investigate the correlation between the alveolar bone thickness (ABT) and tooth inclination. MATERIALS AND METHODS: Cone beam computed tomography scans of 45 subjects with UCLAP (29 boys, 16 girls; mean age = 10.74 ± 1.08 years) were assessed. The distance between the cementoenamel junction (CEJ) and alveolar bone crest (AC), and the ABTs at 3 mm, 6 mm, and the apex were measured on the labial, lingual and distal surfaces of U1. The cleft and normal sides were compared using a paired t-test and Pearson's χ2 test. Pearson's correlation was used to explore the association between the ABT and tooth inclination of cleft-adjacent U1 in the labiolingual and mesiodistal dimensions. RESULTS: The CEJ-AC distances were significantly greater in cleft-adjacent U1 ( P < .01), with more bone height reduction observed labially and distally ( P < .001). The labial, lingual, and apico-distal ABTs were decreased on the cleft side ( P < .01). A positive correlation was found between the apico-labial ABT and the labiolingual inclination ( r = 0.568, P < .01). CONCLUSIONS: Patients with UCLAP have reduced alveolar bone support around the cleft-adjacent U1, and the apico-labial ABT tends to decrease with increasing lingual tooth inclination; however, the correlation was weak.

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BACKGROUND: Fixed orthodontic retainers have numerous advantages, but it is not known whether they can exert pathological forces on supporting tissues around the splinted teeth. The purpose of this study was to investigate how the inclination of the lower anterior teeth can affect dental displacement and also change the direction of occlusal loads exerted to dental and its supporting tissues. METHODS: Four three-dimensional finite element models of the anterior part of the mandible were designed. All the models contained the incisors and canines, their periodontal ligament layers (PDLs), the supporting bone (both spongy and cortical), and a pentaflex splinting wire placed in the lingual side of the teeth. Teeth inclination was considered to be 80° (model 1), 90° (model 2), 100° (model 3), and 110° (model 4) to the horizontal plane. The lower incisors were loaded with a 187-N vertical force. Their displacement patterns and the stress in their PDLs were evaluated. RESULTS: In incisors with 80° of inclination, less than a 0.1-mm lingual displacement was seen on the incisal edge and a similar distance of displacement towards the labial was seen on their root apices. However, in models with 90°-110° of inclination, the incisal edge displaced labially between about 0.01 and 0.45 mm, while root apices displaced lingually instead. By increasing the angle of the teeth, the strain in the periodontal ligament increased from about 37 to 58 mJ. The von Mises stresses around the cervical and apical areas differed for each tooth and each model, without a similar pattern. Increasing the angle of the teeth resulted in much higher cervical stresses in the incisors, but not in the canines. In the lateral incisor, cervical stress increased until 100° of inclination but reduced to about half by increasing the angle to 110°. Apical stress increased rather consistently in the incisor and lateral incisors, by increasing the inclination. However, in the canines, apical stress reduced to about half, from the first to fourth models. CONCLUSIONS: Increasing the labial inclination can mostly harm the central incisors, followed by the lateral incisors. This finding warns against long durations of splinting in patients with higher and/or patients with reduced labial bone thickness.

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OBJECTIVE: The aim of this study was to investigate whether labial tooth inclination and alveolar bone loss affect the moment per unit of force (Mt/F) in controlled tipping and consequent stresses on the periodontal ligament (PDL). METHODS: Three-dimensional models (n = 20) of maxillary central incisors were created with different labial inclinations (5°, 10°, 15°, and 20°) and different amounts of alveolar bone loss (0, 2, 4, and 6 mm). The Mt/F necessary for controlled tipping (Mt/Fcont) and the principal stresses on the PDL were calculated for each model separately in a finite element analysis. RESULTS: As labial inclination increased, Mt/Fcont and the length of the moment arm decreased. In contrast, increased alveolar bone loss caused increases in Mt/Fcont and the length of the moment arm. When Mt/F was near Mt/Fcont, increases in Mt/F caused compressive stresses to move from a predominantly labial apical region to a palatal apical position, and tensile stresses in the labial area moved from a cervical position to a mid-root position. Although controlled tipping was applied to the incisors, increases in alveolar bone loss and labial tooth inclination caused increases in maximum compressive and tensile stresses at the root apices. CONCLUSIONS: Increases in alveolar bone loss and labial tooth inclination caused increases in stresses that might cause root resorption at the root apex, despite the application of controlled tipping to the incisors.

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OBJECTIVE: We measured and analyzed the angle between the longitudinal axis of incisor crown and tooth to provide a reference for orthodontists for selecting orthodontic methods and evaluating treatment results. METHODS: A total of 120 participants were included according to the criteria of Andrews' six keys, and cephalometric radiograph under the instructions of modified natural head position acquirement method was performed. The angles of maxillary incisor crown longitudinal axis, tooth longitudinal axis, occlusion plane (OP), and true vertical (TV) plane were measured, as well as mandibular incisors. RESULTS: As for maxillary incisors, the angle between crown longitudinal axis and TV plane, OP, and tooth longitudinal axis were 11.72°±4.71°, 73.29°±5.69°, and 20.04°±3.71°, respectively. For mandibular incisors, the angle between crown longitudinal axis and TV plane, OP, and tooth longitudinal axis were 16.03°±5.40°, 81.76°±4.81°, and 14.82°±4.01°, respectively. For the maxillary incisor, the angles between crown longitudinal axis and tooth longitudinal axis were mainly within 15° to 25°, whereas those for mandibular incisors were within 10° to 20°. CONCLUSIONS: The longitudinal axis inclinations of the maxillary and mandibular incisor crown and of the incisor tooth need to be considered when cephalometric radiographs are used for treatment planning or for evaluating the treatment result.

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<p><b>OBJECTIVE</b>We measured and analyzed the angle between the longitudinal axis of incisor crown and tooth to provide a reference for orthodontists for selecting orthodontic methods and evaluating treatment results.</p><p><b>METHODS</b>A total of 120 participants were included according to the criteria of Andrews' six keys, and cephalometric radiograph under the instructions of modified natural head position acquirement method was performed. The angles of maxillary incisor crown longitudinal axis, tooth longitudinal axis, occlusion plane (OP), and true vertical (TV) plane were measured, as well as mandibular incisors.</p><p><b>RESULTS</b>As for maxillary incisors, the angle between crown longitudinal axis and TV plane, OP, and tooth longitudinal axis were 11.72°±4.71°, 73.29°±5.69°, and 20.04°±3.71°, respectively. For mandibular incisors, the angle between crown longitudinal axis and TV plane, OP, and tooth longitudinal axis were 16.03°±5.40°, 81.76°±4.81°, and 14.82°±4.01°, respectively. For the maxillary incisor, the angles between crown longitudinal axis and tooth longitudinal axis were mainly within 15° to 25°, whereas those for mandibular incisors were within 10° to 20°.</p><p><b>CONCLUSIONS</b>The longitudinal axis inclinations of the maxillary and mandibular incisor crown and of the incisor tooth need to be considered when cephalometric radiographs are used for treatment planning or for evaluating the treatment result.</p>

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OBJECTIVE: The aim of this study was to investigate whether labial tooth inclination and alveolar bone loss affect the moment per unit of force (M(t)/F) in controlled tipping and consequent stresses on the periodontal ligament (PDL). METHODS: Three-dimensional models (n = 20) of maxillary central incisors were created with different labial inclinations (5°, 10°, 15°, and 20°) and different amounts of alveolar bone loss (0, 2, 4, and 6 mm). The M(t)/F necessary for controlled tipping (M(t)/F(cont)) and the principal stresses on the PDL were calculated for each model separately in a finite element analysis. RESULTS: As labial inclination increased, M(t)/F(cont) and the length of the moment arm decreased. In contrast, increased alveolar bone loss caused increases in M(t)/F(cont) and the length of the moment arm. When M(t)/F was near M(t)/F(cont), increases in M(t)/F caused compressive stresses to move from a predominantly labial apical region to a palatal apical position, and tensile stresses in the labial area moved from a cervical position to a mid-root position. Although controlled tipping was applied to the incisors, increases in alveolar bone loss and labial tooth inclination caused increases in maximum compressive and tensile stresses at the root apices. CONCLUSIONS: Increases in alveolar bone loss and labial tooth inclination caused increases in stresses that might cause root resorption at the root apex, despite the application of controlled tipping to the incisors.

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OBJETIVO: avaliar as alterações nas inclinações dos dentes anteriores causadas pelo tratamento ortodôntico, utilizando-se aparelho Straight-Wire, prescrição II Capelozza, antes e após a fase de nivelamento com fios ortodônticos de aço de secção retangular. MÉTODOS: foram selecionados 17 indivíduos adultos de padrão facial II, má oclusão Classe II, indicados para tratamento ortodôntico compensatório. As inclinações dos dentes anteriores foram avaliadas em três tempos clínicos, após o uso dos fios ortodônticos de diâmetros 0,020" (T1); 0,019" x 0,025" (T2) e 0,021" x 0,025" (T3), através de exames de tomografia computadorizada. Empregou-se a análise de variância de Friedman, com nível de significância de 5 por cento, na comparação entre os tempos. RESULTADOS: observou-se que o fios retangulares empregados não foram capazes de produzir uma mudança significativa na mediana da inclinação dentária, exceto por uma discreta alteração nos incisivos laterais inferiores (p<0,05). Por outro lado, constatou-se que a variação das inclinações observadas era menor no fio retangular 0,021" x 0,025", principalmente para os incisivos superiores (p<0,001). CONCLUSÃO: fios retangulares 0,021" x 0,025" produzem uma maior homogeneidade no grau de variação na inclinação dos incisivos superiores, embora sem mudança significativa na sua mediana.

OBJECTIVE: To evaluate changes in the inclination of anterior teeth caused by orthodontic treatment using a Straight-Wire appliance (Capelozza's prescription II), before and after the leveling phase with rectangular stainless steel archwires. METHODS: Seventeen adult subjects were selected who presented with facial pattern II, Class II malocclusion, referred for compensatory orthodontic treatment. Inclinations of anterior teeth were clinically assessed using CT scans at three different times, i.e., after the use of 0.020-in (T1), 0.019 X 0.025-in (T2) and 0.021 X 0.025-in (T3) archwires. Friedman's analysis of variance was applied with 5 percent significance level to compare the three assessments (T1, T2 and T3). RESULTS: It was noted that the rectangular wires were unable to produce any significant changes in inclination medians, except for a slight change in mandibular lateral incisors (p<0.05). On the other hand, variations in inclination were smaller when 0.021 X 0.025-in archwires were employed, particularly in maxillary incisors (P<0.001). CONCLUSION: The use of rectangular 0.021 X 0.025-in archwires produces more homogeneous variations in the inclination of maxillary incisors, but no significant median changes.

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