Evaluation of Head and Cervical Spine Posture after Therapy with Maxillary Protraction Appliances / Evaluación de la Postura de la Cabeza y la Columna Cervical Después de la Terapia con Aparatos de Protracción Maxilar

SUMMARY: The objective of this study was to evaluate the changes of head and cervical spine posture of skeletal class malocclusion in adolescent with maxillary protraction. Thirty cases of skeletal class malocclusion were randomly selected from the Stomatological Hospital of Shanxi Medical University. High-quality lateral cephalograms were collected including pre- and posttreatment to compare the changes of head and cervical spine posture. Data were processed using SPSS 26.0 statistical software. The paired-t test was used to compare pre- and posttreatment mean angular measurements.A significant difference in the SNA(p<0.001), SNB(p<0.01), and ANB(p<0.001) between T1 and T2 showed an improvement in the sagittal relationships. A significant change was observed in middle cervical spine posture, while upper cervical spine posture variables showed no significant difference after treatment. Skeletal class with maxillary protraction appliance not only led to the improvement of sagittal relationship, but also changed the middle cervical spine posture.

El objetivo de este estudio fue evaluar los cambios en la postura de la cabeza y la columna cervical debido a la maloclusión clase esquelética en adolescentes con protracción maxilar. Treinta casos de maloclusión de clase esquelética fueron seleccionados al azar del Hospital Estomatológico de la Universidad Médica de Shanxi. Se recogieron cefalogramas laterales de alta calidad, incluidos el tratamiento previo y posterior, para comparar los cambios en la postura de la cabeza y la columna cervical. Los datos se procesaron con el software estadístico SPSS 26.0. Se utilizó la prueba t pareada para comparar las medidas angulares medias antes y después del tratamiento. Una diferencia significativa en SNA (p <0,001), SNB (p <0,01) y ANB (p <0,001) entre T1 y T2 mostró una mejora en las relaciones sagitales. Se observó un cambio significativo en la postura de la columna cervical media, mientras que las variables de postura de la columna cervical superior no mostraron diferencias significativas después del tratamiento. La clase esquelética con aparato de protracción maxilar no solo condujo a la mejora de la relación sagital, sino que también cambió la postura de la columna cervical media.

Assessment of pharyngeal airway in Korean adolescents according to skeletal pattern, sex, and cervical vertebral maturation: A cross-sectional CBCT study.

Objective: To investigate airway volumes using cone-beam computed tomography (CBCT) by skeletal patterns, sex, and cervical vertebral maturation (CVM) stages in Korean adolescents. Methods: The sample consisted of pretreatment CBCT and cephalograms of 95 adolescents (aged 12-19) obtained out of 1,611 patients examined for orthodontic treatment from 2018 to 2020 in Kyungpook National University Dental Hospital. The samples were classified into two sex groups; three skeletal pattern groups, four chronological age groups and four CVM stages. Nasopharyngeal volumes (NPV), oropharyngeal volumes (OPV), total pharyngeal airway volume (TAV) and minimum cross-sectional area (MCA) measurements were taken from the CBCT. Multiple linear regression analyses to find out which one of the independent variables are good predictors for airway variables. Significant factors were analyzed by two-way multivariate analysis of variance (MANOVA) then multiple comparisons were analyzed using a t-test, and Fisher least significant difference. Results: Age, sex, CVM, and Sella-Nasion-B point have significant influence on airway variable. Males and females showed similar patterns of change in chronological age groups 1-3; however, males had larger NPV, OPV, and MCA at CVM in group 4. According to CVM stages, males had larger OPV, TAV, and MCA at CVM stage 6 (p-value: 0.019, 0.021, 0.015, respectively) and no sex differences at CVM stages 3, 4, and 5. Conclusions: Skeletal patterns have an effect on airway volume. Sex differences were found in CVM 6.

Alveolar bone thickness and height changes following incisor retraction treatment with microimplants.

OBJECTIVES: To evaluate alveolar bone remodeling following incisor retraction treatment with microimplants and to examine the relationship between crown/root distal movement and thickness/height changes of the alveolus. MATERIALS AND METHODS: A total of 24 patients (mean age, 19.29 ± 4.64 years) with bialveolar protrusion treated by incisor retraction with microimplants were included. The distances of the crown and root tip movements as well as the thickness (alveolar bone thickness [ABT]; labial, lingual, and total) and vertical level (vertical bone level [VBL]; labial and lingual) of the alveolar bone were assessed using cone-beam computed tomography images obtained before treatment (T1) and after treatment (T2). All T1 and T2 variables were compared, and further comparisons of alveolar bone changes were conducted between the two groups based on the distance of the crown (low-crown-movement and high-crown-movement groups) and root movements (low-root-movement and high-root-movement groups). To determine the correlation of the crown or root movement with the variables of alveolar bone changes, Pearson correlation coefficients were calculated. RESULTS: Significant differences were found in all VBL and ABT variables after treatment in both jaws but not in total ABT. Based on the crown and root movements, alveolar bone change significantly differed between the root-movement groups, whereas there was no significant difference between the crown-movement groups. In addition, root movement showed significant correlations with the variables. CONCLUSIONS: Remarkable changes in the height and thickness of alveolar bone were found after microimplant-aided incisor retraction treatment in all groups except for total ABT. Root movement was significantly correlated with the alveolar bone changes.

Correlation between the anatomical morphology of palatal rugae and sex / Correlación entre la morfología anatómica de las rugas palatinas y el sexo

SUMMARY: To investigate the correlation between the anatomical morphology of palatal rugae and sex. The study sample consisted of 120 students studying from Shanxi Medical University, of which 60 were females and 60 were males. The digital model of the palatal rugae was obtained by the 3 Shape TRIOS intraoral scanner. And the shapes of palatal rugae were recorded. Association between palatal rugae shape and sex were tested using Chi-square analysis. And logistic regression analysis (LRA) was carried out to calculate the accuracy of gender prediction using rugae shapes. There was a statistically significant difference between males and females in terms of the distribution of wavy and circular palate rugae. The use of logistic regression analysis obtained a sex predictive value of 65 % when all the rugae shapes were analyzed. Digital images of the palatal rugae morphology contribute to more accurate and convenient for data collection and transformation. It was found that rugae patterns can moderately identify the sex of the specific population when multivariate statistics such as LRA is applied. The palatal rugae morphology can be utilized as an assistant measure for sex identification.

RESUMEN: Investigar la correlación entre la morfología anatómica de las rugas palatinas y el sexo. En la muestra de este estudio se incluyeron 120 estudiantes de la Universidad Médica de Shanxi, (60 mujeres y 60 hombres). El modelo digital de las rugas palatinas se obtuvo mediante escáner intraoral 3 Shape TRIOS, y se registraron las formas de las rugas palatinas. La asociación entre la forma de las rugas palatinas y el sexo se evaluó mediante un análisis de Chi-cuadrado; para calcular la precisión de la predicción de sexo se llevó a cabo un análisis de regresión logística (ARL) Se observó una diferencia estadísticamente significativa entre hombres y mujeres en términos de la distribución de las rugas palatinas onduladas y circulares. El uso de análisis de regresión logística obtuvo un valor predictivo de sexo del 65 % cuando se analizaron todas las formas de las rugas. Las imágenes digitales de la morfología de las rugas palatinas contribuyen a una recopilación de datos más precisa. En este análisis se determinó que los patrones de rugas pueden identificar relativamente el sexo de una población específica, cuando se aplican estadísticas multivariadas como ARL. La morfología de las rugas palatinas se puede utilizar como medida de ayuda para la identificación de sexo.

Evaluation of clinical parameters for the stability of 2 types of miniscrews.

INTRODUCTION: The purpose of this research was to compare insertion techniques and effects on mechanical and clinical parameters between 2 types of miniscrews. METHODS: Forty-four consecutive patients whose orthodontic treatment involved the use of miniscrews (miniscrew A [MA] and miniscrew B [MB]) for anchorage were included in this study. Miniscrews were placed with predrilling or self-drilling; peak maximum insertion torque (MIT) and Periotest values were measured. Cone-beam computed tomography was performed after the insertion of miniscrews and root proximity determination; cortical bone thickness was also analyzed. Periotest values were measured after the application of orthodontic force. RESULTS: Self-drilling produced higher Periotest values (P <0.01) for MA and higher MIT (P <0.01) for MB with closer root proximity (P <0.05). MB had higher MIT and Periotest values with drilling compared with MA (P <0.05); MB also showed closer root proximity (P <0.05). Successful miniscrews had lower MIT (P <0.05) for MB and lower Periotest values (P <0.01) for both MA and MB, with significantly more distant root proximity (P <0.01). Self-drilling produced higher Periotest values at the time of placement (P <0.01) and after 4 weeks (P <0.05) in MA. Drilling produced higher Periotest values for MB at the time of placement (P <0.05). MIT had positive correlations with Periotest values for MB with self-drilling (P <0.01) and with root proximity for MA with drilling (P <0.01). Periotest values had negative correlations with root proximity for MA and the MB group with drilling (P <0.01). CONCLUSIONS: For miniscrews with larger diameters, higher MIT may result in more mobility (higher Periotest values). Drilling can avoid root contact and enhance primary stability, thus producing lower Periotest values.

Correlation between insertion torque and peri-implant bone strain during placement of orthodontic mini-implants: A finite element study.

INTRODUCTION: Insertion torque is the amount of torque exerted on the implant to tighten into the bone. We investigated whether insertion torque values could be correlated with the strain level in the peri-implant cortical bone resulting from mini-implant insertion. METHODS: The insertion of a standard size mini-implant (φ 1.4 mm × 7 mm) into maxillary alveolar bone was simulated using the finite element method. A total of 3600 calculation steps were employed to numerically reproduce the mini-implant insertion process and analyze the insertion torque and strain distribution in bone. Special attention was given to the relationship between insertion torque values and strain level in the cortical bone at the final tightening. The strain level was quantified using the following 3 strain parameters: (1) average insertion strain, (2) peak insertion strain recorded near the mini-implant thread tips, and (3) the size of the damage zone in the cortical bone. Correlations between the insertion torque values and these 3 parameters were analyzed using linear regression. RESULTS: Direct proportionality and strong correlation were found between the insertion torque values and each of the 3 strain parameters: average insertion strain (r2 = 0.91), peak insertion strain (r2 = 0.91), and the size of damage zone (r2 = 0.90) in the peri-implant cortical bone. CONCLUSIONS: The results of this finite element method study demonstrated that insertion torque could serve as a reliable indicator of the strain level in the peri-implant cortical bone resulting from mini-implant insertion.

Biomechanical analysis for total distalization of the maxillary dentition: A finite element study.

INTRODUCTION: This study aimed to identify the tooth movement patterns relative to various force angulations (FAs) when distalizing the total maxillary dentition. METHODS: Long-term orthodontic movement of the maxillary dentition was simulated by accumulating the initial displacement of teeth produced by elastic deflection of the periodontal ligament using a finite element analysis. Distalization forces of 3 N were applied to the archwire between the maxillary canine and first premolar at 5 different FAs (-30°, -15°, 0°, 15°, and 30°) to the occlusal plane. RESULTS: Maxillary incisors and molars showed lingual and distal tipping at all FAs, respectively. At a force angulation of 30°, almost bodily distalization of the total maxillary dentition occurred, but incisors showed considerable lingual tipping because of the effect of clearance gap (0.003-in, 0.022 × 0.025-in bracket slot, 0.019 × 0.025-in archwire) and elastic deflection of the archwire. Medial displacement of the maxillary anterior teeth occurred because of lingual tipping during distalization. The occlusal plane rotated clockwise at all FAs because of extrusion of the maxillary incisors and intrusion of the maxillary second molars, and the amounts decreased as FA increased. CONCLUSIONS: Tooth movement patterns during distalization of the total maxillary dentition were recognized. With an understanding of the mechanics, a proper treatment plan can be established.

Biomechanical analysis for total mesialization of the maxillary dentition: A finite element study.

INTRODUCTION: The purpose of this study was to analyze and clarify tooth movement during mesialization of the whole maxillary dentition with various force angulations (FAs). METHODS: A finite element method was used to simulate the long-term orthodontic movement of the maxillary dentition by accumulating the initial displacement of teeth produced by elastic deformation of the periodontal ligament. A mesial force of 3 N was applied to the maxillary second molar at 5 different FAs (-30°, -15°, 0°, 15°, and 30°) to the occlusal plane. RESULTS: At an FA of 28°, the line of action of the force passed through the center of resistance of the maxillary whole dentition. With all FAs, the central incisors and molars tipped labially and mesially, respectively. The tipping angles gradually decreased as the FAs shifted from -30° to 30°. The molars tipped lingually with FAs of -30° and -15°, whereas they tipped buccally with FAs of 0°, 15°, and 30°. The molars tended to rotate mesiolingually more as the angle of force increased toward an FA of 30°. The occlusal plane rotated counterclockwise with FAs of -30°, -15°, and 0°, whereas it rotated clockwise with FAs of 15° and 30°. With an FA of 30°, buccal tipping and mesiolingual rotation of the molars, and the change in the occlusal plane angle decreased when the transpalatal arch (TPA) was fixed to the first molars and decreased, even more when the TPA was fixed to the second molars rather than the first molars, when a thicker TPA was used, and when the TPA was fixed to both molars rather than a single molar. CONCLUSIONS: There was a correlation between tooth movement during mesialization of the whole maxillary dentition and the angle at which the force was applied.

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study.

INTRODUCTION: Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient. OBJECTIVE: To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician. METHODS: 82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort. RESULTS: The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only. CONCLUSIONS: Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

A Study on the Status of Application of Health Insurance Fees for Nursing Activities of Nurses in Rehabilitation Unit / 재활간호학회지

Purpose@#The purpose of this study was to analyze the nursing activities of registered nurses working in rehabilitation units, and to investigate the application of the health insurance fee for each nursing practice. @*Methods@#Using the Delphi survey method, nursing activities were analyzed as job-task-task elements. Then, the status of the application of health insurance fees was investigated for the task elements according to National Health Insurance Benefit. @*Results@#15 jobs, 61 tasks, and 290 task elements were derived as nursing activities in rehabilitation units.According to the opinion by the expert panel, Among the 290 task elements, 166 (57.2%) out of 290 take elements should be accepted as insurance fees (fee agreement CVR≥0.56). However, the health insurance was applied to only 40 items (24.1%) for nursing management fees, 25 items for nursing care (15.1%), and 26 items for other rehabilitation related medical fees (15.7%). 82 items (49.4%) were not covered by insurance, and most educational interventions were not covered. @*Conclusion@#To provide high-quality nursing services in rehabilitation units, it is essential to apply an appropriate level of health insurance coverage. Further research to expand the application of medical fees related to rehabilitation and institutional arrangements to obtain recognition of the fees for nursing services are necessary.

Stability of immediately loaded 3 mm long miniscrew implants: a feasibility study

ABSTRACT Introduction: Shorter miniscrew implants (MSIs) are needed to make orthodontics more effective and efficient. Objective: To evaluate the stability, insertion torque, removal torque and pain associated with 3 mm long MSIs placed in humans by a novice clinician. Methods: 82 MSIs were placed in the buccal maxillae of 26 adults. Pairs of adjacent implants were immediately loaded with 100g. Subjects were recalled after 1, 3, 5, and 8 weeks to verify stability and complete questionnaires pertaining to MSI-related pain and discomfort. Results: The overall failure rate was 32.9%. The anterior and posterior MSIs failed 35.7% and 30.0% of the time, respectively. Excluding the 10 MSIs (12.2%) that were traumatically dislodged, the failure rates in the anterior and posterior sites were 30.1% and 15.2%, respectively; the overall primary failure rate was 23.6%. Failures were significantly (p= 0.010) greater (46.3% vs 19.5%) among the first 41 MSIs than the last 41 MSIs that were placed. Excluding the traumatically lost MSIs, the failures occurred on or before day 42. Subjects experienced very low pain (2.2% of maximum) and discomfort (5.5% of maximum) during the first week only. Conclusions: Shorter 3 mm MSIs placed by a novice operator are highly likely to fail. However, failure rates can be substantially decreased over time with the placement of more MSIs. Pain and discomfort experienced after placing 3 mm MSIs is minimal and temporary.

RESUMO Introdução: Mini-implantes (MIs) mais curtos são necessários para uma Ortodontia mais eficiente e efetiva. Objetivo: Avaliar a estabilidade, torque de inserção e de remoção e dor associada a MIs de 3mm instalados em humanos por um ortodontista principiante. Métodos: 82 MIs foram instalados na região vestibular da arcada superior de 26 adultos. Pares de mini-implantes adjacente receberam carga imediata de 100g. Após 1, 3, 5 e 8 semanas, os pacientes foram reavaliados para verificar a estabilidade e preencher um questionário sobre a dor e o desconforto relacionados aos MIs. Resultados: A taxa geral de falhas foi de 32,9%, sendo de 35,7% para os MIs anteriores e 30% para os MIs posteriores. Excluindo os 10 MIs que foram perdidos por trauma (12,2%), a taxa de falha nas regiões anterior e posterior foram de 30,1% e 15,2%, respectivamente e ocorreram no 420 dia ou antes. A taxa geral de falha primária foi de 23,6%. A taxa de falha foi significativamente maior (p=0,010) nos primeiros 41 MIs do que nos 41 últimos (46,3% vs. 19,5%). As experiências relacionadas à dor foram baixas (2,2% máximo), assim como ao desconforto (5,5% máximo) durante a primeira semana. Conclusão: MIs de 3mm instalados por um novato são mais propensos a falhas. Porém, as taxas de falha podem diminuir substancialmente com a instalação de mais MIs com o decorrer do tempo. A dor e o desconforto após a instalação desses dispositivos são mínimos e temporários.

Morphological changes of frankel functional regulator III in mixed dentition with class III malocclusion / Cambios morfológicos del regulador funcional frankel III en dentición mixta con maloclusión clase III

The aim of this study was to evaluate the hard and soft tissue profile changes following treatment of functional and mild skeletal class III malocclusion in mixed dentition by means of the Frankel functional regulator (FR-3) appliance, and to reveal the mechanism and effectiveness of treatment with FR-3 appliance. Twenty-six patients (chronological mean age, 8.7±1.4 years; mean treatment duration, 10.3±1.3 months) with functional and mild skeletal class III malocclusion were selected and treated with FR-3 appliances. Lateral cephalogram was taken pre- and post-treatment, and the data was analyzed by paired-samples t test with SPSS22.0 software package. Differences were considered statistically significant at P < 0.05. The results demonstrated that the FR-3 appliance produced a statistically significant decrease in L1-NB, L1-MP, U1-L1 (P<0.01) and an increase greatly in ANB, MP-FH, Y axis, ANSMe, ANS-Me/N-Me and overjet (P<0.01). SNA, SNB were increased significantly (P<0.05). Meanwhile, N'-Sn-Pog', ULSn-SN, LLSiSN increased, S-N'-Si, LL-EP decreased with significant difference (P<0.01). S-N'-Sn, Cm-Sn-UL, UL-EP, Sn-Mes and Ns-Mes increased with significant difference (P<0.05). Therefore it was concluded that after FR-3 treatment, the position of mandible may rotate clockwise backwards and downwards, with the labioversion of upper incisors and linguoversion of lower incisors. Although point A moved mesially, the length and position of the maxilla did not change significantly. With the protrusion of upper lip and the retrusion of lower lip, the relationship among nose, upper lip, lower lip and chin become harmonious, the profile of soft tissue is more coordinated and attractive.

El objetivo de este estudio fue evaluar los cambios en el perfil de los tejidos duros y blandos después del tratamiento de la maloclusión funcional y leve de la clase III esquelética en la dentición mixta mediante el aparato regulador funcional Frankel (FR-3), y revelar el mecanismo y efectividad del tratamiento con el aparato FR-3. Veintiseis pacientes (edad media 8,7 ± 1,4 años; duración media del tratamiento, 10,3 ± 1,3 meses) con maloclusión funcional y leve de clase esquelética III fueron seleccionados y tratados con aparatos FR-3. El cefalograma lateral se tomó antes y después del tratamiento, y los datos se analizaron mediante la prueba t de muestras con el software SPSS22.0. Las diferencias se consideraron estadísticamente significativas a P <0,05. Los resultados demostraron que el dispositivo FR-3 produjo una disminución estadísticamente significativa en L1-NB, L1MP, U1-L1 (P <0,01) y un gran aumento en ANB, MP-FH, eje Y, ANS-Me, ANS -Me / N-Me y overjet (P <0,01). SNA, SNB se incrementaron significativamente (P <0,05). Mientras tanto, N'Sn-Pog', ULSn-SN, LLSi-SN aumentaron, S-N'-Si, LL-EP disminuyeron con una diferencia significativa (P <0,01). S-N'-Sn, Cm-Sn-UL, UL-EP, Sn-Mes y Ns-Mes aumentaron con una diferencia significativa (P <0,05). Por lo tanto, se concluyó que después del tratamiento con FR-3, la posición de la mandíbula puede girar en sentido reloj hacia atrás y hacia abajo, con labioversión de los incisivos superiores y linguoversión de los incisivos inferiores. Aunque el punto A se movió mesialmente, la longitud y la posición del maxilar no cambiaron significativamente. Con la protuberancia del labio superior y la retrusión del labio inferior, la relación entre la nariz, el labio superior, el labio inferior y el mentón se armoniza, el perfil del tejido blando es más coordinado y atractivo.

Estimation of the prevalence of malocclusion on the basis of nationwide oral health examinations of pre-adolescent and adolescent students during 2012-2017.

OBJECTIVE: To investigate the prevalence of malocclusion with respect to grade, sex, and year among Korean pre-adolescent and adolescent students during 2012-2017. METHODS: A total of 165,996 students (first grade [E1, 6-7 years of age], fourth grade [E4, 9-10 years], seventh grade [M1, 12-13 years], and tenth grade [H1, 15-16 years]) were selected by stratified sampling method and underwent the nationwide oral health examination performed by the Ministry of Education, Republic of Korea. The malocclusion assessments based on dentists' judgments were "no malocclusion," "needs orthodontic treatment (N-OTx)," and "under orthodontic treatment (U-OTx)." The sum of N-OTx and U-OTx cases was determined as the number of students with malocclusion. After analyzing the prevalence of malocclusion according to grade, sex, and year-by-year differences, Pearson correlation analyses and two-way analyses of variance were performed. RESULTS: The prevalence of malocclusion was 18.7%, which increased with the grades (E1 [8.3%] < E4 [15.8%] < M1 [22.9%] < H1 [25.3%], p < 0.001). However, there was no significant difference in the prevalence of malocclusion in each grade group for the period (p > 0.05) without significant correlation (E1, ρ = 0.129; E4, ρ = -0.495; M1, ρ = 0.406; H1, ρ = -0.383; all p > 0.05). The prevalence of malocclusion within each grade group over the six-year period was more prominent in the female (p < 0.0001). CONCLUSIONS: Further studies are necessary to modify the malocclusion assessment method to account for specific types of malocclusion in pre-adolescent and adolescent students.

Comparison of inclination and vertical changes between single-wire and double-wire retraction techniques in lingual orthodontics.

OBJECTIVE: The Heat Induction Typodont System (HITS), used in some recent studies, has a distinct advantage over previous tooth movement simulation methods. This study aimed to compare inclination and vertical changes between the single-wire and double-wire techniques during en masse retraction with different lengths of lever arms in lingual orthodontics using an upgraded version of the HITS. METHODS: Duet lingual brackets, which have two main slots, were used in this study. Forty samples were divided into four groups according to the length of the lever arm (3-mm or 6-mm hook) and the retraction wire (single-wire or double-wire). Four millimeters of en masse retraction was performed using lingual appliances. Thereafter, 3-dimensional-scanned images of the typodont were analyzed to measure inclination and vertical changes of the anterior teeth. RESULTS: Incisor inclination presented more changes in the single-wire groups than in the double-wire groups. However, canine inclination did not differ between these groups. Regarding vertical changes, only the lateral incisors in the single-wire groups presented significantly larger values than did those in the double-wire groups. Combining the effect of hook lengths, among the four groups, the single-wire group with the 3-mm hook had the highest value, while the double-wire group with the 6-mm hook showed the least decrease in crown inclination and extrusion. CONCLUSIONS: The double-wire technique with an extended lever arm provided advantages over the single-wire technique with the same lever arm length in preventing torque loss and extrusion of the anterior teeth during en masse retraction in lingual orthodontics.

Mechanical and clinical evaluation of the effect of microscrew on root proximity and cortical bone thickness.

BACKGROUND/OBJECTIVES: Primary stability is required for successful use of microscrew. This study investigated correlations among biomechanical, morphological, and clinical values in relationship to root contact and different placement locations. MATERIALS/METHODS: Thirty-three microscrews were placed between the molars (n = 18) or in the body of the mandible (n = 15) in three pigs. Insertion torque, Periotest, resonance frequency analysis (RFA), and static and dynamic stiffness were measured. Cone beam computed tomography was performed before and after the insertion of microscrews. Interproximal microscrews were divided into root contacted microscrews (n = 9) and non-root contact microscrews (n = 9). Factorial analysis of variance was conducted, with significance set at P < 0.05. RESULTS: A significant difference was observed between bodily and root contacted microscrews in Periotest, RFA, static and dynamic stiffness, Tanδ, and bone density (RFA, P = 0.045; all others, P < 0.001). A significant difference was observed between bodily and non-root contact microscrews in Periotest, RFA, and bone density (RFA, P = 0.025; all others, P < 0.001). A significant difference was observed in static (P = 0.01) and dynamic (P = 0.038) stiffness between microscrews with and without contact. Dynamic stiffness (P = 0.02) and Tanδ (P = 0.03) showed significant correlations with Periotest results only in bodily microscrews. LIMITATIONS: Since a pig bone was used, some differences in the quality and quantity of the bone might be observed between humans. CONCLUSIONS/IMPLICATIONS: Stiffness values distinguished between microscrews with and without contact. Periotest and RFA results indicated that bodily microscrews were more stable than interproximal microscrews. Periotest and RFA may be useful with large, microscrews and/or in thick cortical bone, but further investigation is required to determine the stability of interproximal microscrews.

Effectiveness of Tongue Crib Combination Treating Severe Skeletal Angle Class III Malocclusion in Mixed Dentition.

OBJECTIVE: To evaluate the treatment effects of tongue crib combination for treating severe skeletal Angle class III malocclusion in mixed dentition by X-ray cephalometric analysis. MATERIALS AND METHODS: A sample of 22 patients with severe skeletal Angle class III malocclusion of deficiency maxilla and overgrown mandible in mixed dentition was prospectively collected and equally divided into two groups. The patients (males 6 and females 5; mean age 8.35 ± 1.6 years) in the study group were treated with tongue crib combination, and the untreated patients (females 5, males 6; mean age 8.12 ± 1.3 years) served as the control group. X-ray cephalometric films were measured before and after treatment for comparing the change of occlusion, maxilla, mandible, and soft tissue. A paired t-test was used by SPSS 21.0 statistical software. The intragroup data were compared by using the Wilcoxon test, and intergroup data were compared by using the Mann-Whitney U test (p < 0.05). RESULTS: In the study group, all patients got a favorable facial profile. Anterior and posterior teeth crossbite and upper and lower first molars relationships were improved. In cephalometric measurement, significant changes were noted in the maxillary skeletal component. The significant forward growth of the maxilla exhibited in a statistical increase of SNA, ANS-PNS, Wits appraisal, p < 0.05. The mandible revealed slightly posterior rotation by no significant decrease in SNB and no change Co-Gn. After 1-year of retention, the changes of the teeth showed self-correction and facial profile improved further. Regarding vertical changes, maintenance of growth was shown a small non-significant increase of FMA, N-Me, and ANS-Me. There is a significant difference from those in the control group (p < 0.05). CONCLUSION: Tongue crib combination is an effective device for the patients in the growing period with skeletal Angle class III malocclusion by improving the maxillary growth and limiting the mandibular growth. HOW TO CITE THIS ARTICLE: Zhao W, Chen Y, Kyung H-M, et al. Effectiveness of Tongue Crib Combination Treating Severe Skeletal Angle Class III Malocclusion in Mixed Dentition. Int J Clin Pediatr Dent 2020;13(6):668-676.

Effect of soft tissue thickness on the morphology of lip in orthodontic treatment / Efecto del grosor del tejido blando en la morfología del labio en el tratamiento de ortodoncia

The aim of this study was to evaluate the effect of soft tissue thickness of upper lip on lip retraction in orthodonticaltreated females and identify the ratio of maxillary incisor retraction to upper lip retraction. Pre- and post-treatment lateral cephalograms of 100 adults were examined to measure the lip thickness in upper lip and establish the classification standard. All subjects were treated with 4 first premolar extractions followed by upper central incisors retraction. Pre- and post-treatment lateral cephalograms of 19 patients were reviewed to determine the changes of the upper lip and incisor positions through landmarks displacement. An independent-samples t test and one-way analysis of variance were performed. The correlations between maxillary incisor retraction and upper lip retraction were explored by the Pearson correlation method. P-values<0.05 were considered statistically significant. The lip thickness of adult male patients was greater than that of adult female patients. The average ratio of maxillary incisor retraction to upper lip repositioning was 1.6:1,1.9:1 and 2.2:1 in the thin lips group, normal lips group and thick lips group, respectively. Gender differences exist in the thickness of upper lip. Horizontal changes of the maxillary incisor showed a significant correlation to horizontal changes of the upper lip (P<0.001).There were negative correlations between the thickness of upper lip and the ratio between change in maxillary incisor protrusion and change in upper lip protrusion.

El objetivo de este estudio fue evaluar el efecto del grosor de los tejidos blandos del labio superior, sobre la retracción del labio en mujeres tratadas con ortodoncia e identificar la proporción de retracción del diente incisivo maxilar con respecto a la retracción del labio superior. Se examinaron cefalogramas laterales, previos y posteriores al tratamiento de 100 adultos, para medir el grosor del labio superior y establecer un estándar de clasificación. Todos los sujetos fueron tratados con 4 extracciones de los primeros premolares seguidas de retracción de los incisivos centrales superiores. Se revisaron los cefalogramas laterales, previos y posteriores al tratamiento de 19 pacientes, para determinar los cambios del labio superior y las posiciones de los incisivos a través del desplazamiento de los puntos de referencia. Se realizó una prueba t de muestras independientes y un análisis de varianza de una vía. Las correlaciones entre la retracción del incisivo maxilar y la retracción del labio superior se exploraron mediante el método de correlación de Pearson. Los valores de p<0,05 fueron considerados estadísticamente significativos. El grosor de los labios de los pacientes adultos masculinos fue mayor que el de las pacientes adultas. La relación promedio de la retracción del incisivo maxilar al reposicionamiento del labio superior fue de 1,6:1,1; 9:1 y 2,2:1 en el grupo de labios delgados, grupo de labios normales y grupo de labios gruesos, respectivamente. Existen diferencias de sexo en el grosor del labio superior. Los cambios horizontales del incisivo maxilar mostraron una correlación significativa con los cambios horizontales del labio superior (P<0,001). Hubo correlaciones negativas entre el grosor del labio superior y la relación entre el cambio en la protuberancia del incisivo maxilar y el cambio en la protrusión del labio superior.

Clinical study on the posterior occlusal plane and morphology of temporomandibular joint / Estudio clínico sobre el plano oclusal posterior y la morfología de la articulación temporomandibular

The objective of the study was to investigate the morphological features of the temporomandibular joint in adult patients with posterior occlusal plane and different inclinations. Fifty five skeletal I occlusion patients with average were included, shooting CBCT in the intercuspal position, divided into 3 groups according to OPP-FH angle, and measurement of the temporomandibular joint morphology was calculated with cone beam computed tomography (CBCT) special software Invivo 5.0, Statistical analysis of three groups of data using SPSS23.0. The condyle usually locates in the middle of the fossa, the maximum axial area of the condyle (A) was statistically significant between the group 1 and the group 3. The internal and external diameter (MD) of the condyle was statistically significant between group 1 and group 3, and group 2 and group 3. The bilateral TMJ morphological features of the three groups were basically symmetrical. The position of the condyle in the fossa is mostly centered, and some of the posterior, the maximum axial area and the internal and external diameter of the condyle are different in three groups.

El objetivo de este estudio fue investigar las características morfológicas de la articulación temporomandibular (ATM) en pacientes adultos con plano oclusal posterior y diferentes inclinaciones. Se incluyeron 55 pacientes con oclusión esquelética tipo I, visualizados por tomografía computarizada de haz cónico (CBCT) en posición intercuspiana, y se dividieron en 3 grupos según el ángulo OPP-FH. La medición morfológica de la articulación temporomandibular se calculó con CBCT y mediante el software especial Invivo 5.0. El análisis estadístico de datos se realizó con el software SPSS 23.0. El cóndilo de la mandíbula generalmente se ubica en el centro de la fosa; el área axial máxima del cóndilo de la mandíbula (A) fue estadísticamente significativa entre los grupos 1 y 3. Los datos de los diámetros medial y lateral (DM) del cóndilo de la mandíbula fueron estadísticamente significativos entre los grupos 1 y 3 y los grupos 2 y 3. Las características morfológicas de la ATM de los tres grupos fueron básicamente simétricas. La posición del cóndilo de la mandíbula en la fosa fue principalmente centrada, y parte del área axial máxima, posterior y los diámetros medial y lateral del cóndilo de la mandíbula fueron diferentes en los tres grupos.

Evaluations of miniscrew type-dependent mechanical stability.

BACKGROUND: Miniscrew has been widely used as an absolute anchorage in orthodontic treatment. Types of miniscrew with different diameter, length, shape, and thread dimensions may have a substantial effect on mechanical stability of the miniscrew system. Thus, the objective of this study was to evaluate miniscrew type-dependent mechanical stability to assess mechanical properties of miniscrew systems in various thickness of artificial bone block using different measurement tools. METHODS: Two types of miniscrews (15 Tomas and 15 AbsoAnchor) were placed in artificial bone block with different thickness of 1.5, 2.0, 3.0 mm. Values of maximum insertion torque, removal torque, Periotest, implant stability quotient, static stiffness, dynamic stiffness, and energy dissipation ability were assessed for each miniscrew system. FINDINGS: The maximum insertion torque, removal torque, implant stability quotient, static and dynamic stiffness values significantly increased when the miniscrews were placed in thicker bone block while Periotest values decreased. The static stiffness, Periotest and implant stability quotient values were significantly correlated each other and also with other mechanical properties (p < 0.001) except tan δ (p > 0.35). However, the slopes of some correlations and absolute values of measurement were significantly different dependent on the miniscrew types (p < 0.025). INTERPRETATION: The current findings suggest that miniscrew type-dependent calibrations are required to estimate mechanical stability of the miniscrew systems despite the utilization of same measurement tool.